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Full text of "Ecological study of the Amoco Cadiz oil spill : report of the NOAA-CNEXO Joint Scientific Commission"

Na/JA/CNfiXO 0<+ 82- 

ECOLOGICAL STUDY OF THE 
AMOCO CADIZ OIL SPILL 



Report of the NOAA-CNEXO 
Joint Scientific Commission 



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U. S. DEPARTMENT OF COMMERCE 

National Oceanic and Atmospheric Administration 

CENTRE NATIONAL POUR I'EXPLOITATION DES OCEANS 



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ECOLOGICAL STUDY OF THE 
AMOCO CADIZ OIL SPILL 



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Report of the NOAA-CNEXO 
Joint Scientific Commission 



October 1982 



4Wt, U. S. DEPARTMENT OF COMMERCE 



1%^KA- Malcolm Baldnge, Secretary 
^B^ National Oceanic and Atmospheric Administration 
John V. Byrne, Administrator 



CENTRE NATIONAL POUR I'EXPLOITATION DES OCEANS 



DISCLAIMER 



Mention of a commercial company or product does not constitute an 
endorsement by NOAA Environmental Research Laboratories. Use for 
publicity or advertising purposes of information from this publi- 
cation concerning proprietary products or the tests of- such 
products is not authorized. 



ii 



TABLE OF CONTENTS 

Page 
Preface v 

I. Physical, Chemical, and Microbiological Studies 
After the AMOCO CADIZ Oil Spill 

ATLAS, R.M. 

Microbial Degradation within Sediment Impacted by 

the AMOCO CADIZ Oil Spill 1 

BALLERINI, D. , DUCREUX, J., and RIVIERE, J. 

Laboratory Simulation of the Microbiological 

Degradation of Crude Oil in a Marine Environment . . 27 

BOEHM, P.D. 

The AMOCO CADIZ Analytical Chemistry Program .... 35 

DOU, H., GIUST, G., and MILLE, G. 

Studies of Hydrocarbon Concentrations at the 

He Grande and Baie de Lannion Stations Polluted 

by the Wreck of the AMOCO CADIZ 101 

DUCREUX, J. 

Evolution of the Hydrocarbons Present in the 

Sediments in the Aber Wrac'h Estuary Ill 

MARCHAND, M., BODENNEC, G. , CAPRAIS, J.-C, and 
PIGNET, P. 

The AMOCO CADIZ Oil Spill, Distribution and 

Evolution of Oil Pollution in Marine Sediments . . . 143 

WARD, D.M., WINFREY, M.R., BECK, E., and BOEHM, P. 
AMOCO CADIZ Pollutants in Anaerobic Sediments: 
Fate and Effects on Anaerobic Processes 159 

II. Biological Studies After the AMOCO CADIZ SPILL 

GLEMAREC, M. and HUSSENOT, E. 

Reponses des Peuplements Subtidaux a la Perturbation 

Creee par 1 'AMOCO CADIZ dans les Abers Benoit et 

Wrac'h 191 

CABIOCH, L., DAUVIN, J.-C, RETIERE, C, RIVAIN, V. and 

ARCHAMBAULT, D. 

Les Effets des Hydrocarbures de 1 'AMOCO-CADIZ sur 

les Peuplements Benthiques des Baies de Morlaix et 

de Lannion d'Avril 1978 a Mars 1981 205 



in 



Page 

BOUCHER, G., CHAMROUX, S., LE BORGME, L. , and MEVEL, G. 

Etude Experimental e d'une Pollution par Hydrocarbures 

dans un Microecosysteme Sedimentaire. I: Effet de 

i Contamination du Sediment sur la Meiofaunr- 22 " 

BODIN, P. and BOUCHER, D. 

Evolution a floyen-Terme du Meiobenthos et du 

Microphytobenthos sur Quelques Plages Touchees par 

la Maree Noire de 1 'AMOCO -CADIZ 245 

NEF and HAENSLY, W.E. 

Long-Term Impact of the AMOCO CADIZ Crude Oil 

Spill on Oysters Crassostrea gigas and Plaice 

: ieuronectes platessa From Aber Benoit and Aber 

Wrac'h, Brittany, France. I. Oyster Histopathology. 

II Hetrcleum Contamination and Biochemical 

Indices of Stress in Oysters and Plaice . . . 269 

LEVASSEUR, J.E. and JORY, M.-L. 

Retablissement Naturel d'une Vegetation de Marais 

Mari times Alteree par les Hydrocarbures de 1 'AMOCO 

CADIZ: Modalites et Tendances 329 

SENECA, E.D. and BROOME, S.W. 

Restoration of Marsh Vegetation Impacted by the 

AMOCO CADIZ Oil Spill and Subsequent Cleanup 

Operations at He Grande, France 363 

LE CAMPION-ALSUMARD, T. , PLANTE-CUNY, M.-R., and 

VACELET, E. 

Etudes Microbiologiques et Microphytiques dans 

les Sediments des Marais Maritimes de l'lle Grande 

a la Suite de la Pollution par 1 'AMOCO CADIZ 421 

CHASSE, C. and GUENOLE-BOUDER, A. 

1964-1982, Comparaison Quantitative des Populations 

Benthiques des Plages de St Efflam, St Michel-en- 

Greve Avant, Pendant et Depuis le Naufrage de 

1 'AMOCO-CADIZ 451 



iv 



PREFACE 

At approximately 11:30 p.m. on Thursday, March 16, 1978, the super- 
tanker Amoco Cadiz went aground on a rock outcropping 1.5 km offshore of 
Portsall on the northwest coast of France. The vessel contained a cargo 
of 216,000 tens of crude oil and 4,000 tons of bunker fuel. At 6:00 a.m. 
on Friday, March 17, the vessel broke just forward of the wheelhouse and 
thus started the largest oil spill in maritime history. During the 
course of the next 15 days, the bunker fuel and contents of all 13 loaded 
cargo tanks, which contained two varieties of light mideastern crude oil, 
were released into the ocean. The oil quickly became a water-in-oil 
emulsion (mousse) of at least 50% water, and heavily impacted nearly 
140km of the Brittany coast from Portsall to He de Brehat. At one time 
or another, oil contamination was observed along 393 km of coastline and 
at least 60 km offshore. Impacted areas included recreational beaches, 
mariculture impoundments, and a substantial marine fishery industry. 

h arcr, .3, r. »,ilmot N. Hess, Director of the . v.v , - /omental 
Research Laboratories (ERL) of the National Oceanic and Atmospheric 
Administration (N0AA), contacted Dr. Lucien Laubier, Director of the 
Centre Oceanologique de Bretagne (COB) of the Centre National pour 
1 'Exploitation des Oceans (CNEX0), the French national oceanographic 
organization. Dr. Hess and Dr. Laubier arranged for participation by 
United States scientists in a joint Franco-American investigation of 
physical and chemical manifestations of the spill. On March 24, the 
agreement was expanded to include cooperative biological investigations 
through contacts initiated by Dr. Eric Schneider, Director of the 
Environmental Protection Agency's Environmental Research Laboratory in 
Narragansett, Rhode Island. 

N0AA personnel arrived on March 19 to join the investigation 
initiated on March 17 by several French scientific teams. Initial 
photographic over-flights and active beach sampling began on Tuesday, 
March 21, followed by initial chemical sampling by vessel on Friday, 
March 24. The team was supplemented with EPA biological observers on 
Sunday, March 26. Sampling has continued by some segments of this 
original team until the present time. 

Throughout the period of investigation, active interaction and 
coordination with the French scientific community have taken place under 
the auspices of C0B/CNEX0. All sampling has been coordinated with the 
general ecological impact study designed by the French Ministry of 
Environment, organized, ,by CNEX0, and operated by several scientific 
institutions in France^ , making possible a more thorough evaluation of 
the effects of the incident than would otherwise have been possible. 



- National Museum of Natural History, National Geographic Institute, 
French Institute of Petroleum, Scientific and Technical Institute of 
Marine Fisheries, University of Western Brittany, University P. and 
M. Curie, Paris VI, and the National Center for the Exploitation of the 
Oceans. 



About three months after the oil spill the U.S. team prepared a 
"Preliminary Scientific Report on the Amoco Cadiz Oil Spill" covering 
data up to May 15, 1978. This document covered only the period of acute 
effects. A one-day symposium on the Amoco Cadiz spill was held in Brest 
on June 7, 1978, and published soon after. It was obvious from these 
initial observations that a period of years would be required to under- 
stand what had happened to these portions of the coast where the oil had 
settled in and not been cleansed promptly. 

During this early period of study of the spill Mr. Russ Mallatt of 
the Amoco Trading Company had several discussions with Drs. Hess, 
Laubier and Schneider. Mr. Mallatt was the General Manager for 
Environmental Conservation and Toxicology of Amoco. Discussion with 
Mr. Mallatt during the first two months after the spill identified 
Amoco's interests in carrying out long-term studies of the effects of the 
oil spill. These early contacts were followed up by substantial 
discussions between Mr. John Linsner of Amoco and Mr. Eldon Greenberg, 
General Counsel of NOAA. These discussions culminated with an agreement 
being signed by Amoco and NOAA to carry out long-term studies of the 
effects of the spill. The study would cover three years and would be a 
joint French-U.S. activity. A Joint NOAA/CNEXO Scientific Commission was 
established through another agreement between the two agencies signed 
June 2, 1978. Amoco would transfer money to NOAA and the Joint 
Commission, chaired by Drs. Hess and Laubier, would determine the 
research program to be carried out, the investigators to do the research, 
and the funding levels. The Joint Commission would also monitor the 
progress of the studies and be responsible for making the final report. 
One of its major goals was to make U.S. and French scientific teams work 
together in a common effort to better understand the consequences of the 
wreckage. 

The Joint Commission first met in Brest at the CNEXO Laboratory on 
July 18, 1978. Taking into account the French program to assess the 
long-term ecological impact of the oil spill funded by the Ministry of 
Environment, it determined that the most important areas for research 
were: 

1. Heavily impacted subtidal areas like the Abers and the Bays 
of Morlaix and Lannion. 

2. Heavily impacted intertidal areas such as St. Efflam and the 
salt marsh at He Grande. 

3. The detailed chemical evolution of the petroleum hydrocarbons. 

4. Biodegradation of petroleum. 

The second meeting of the Joint Commission, held in Washington, 
D.C., on October 12, 1978, reviewed the work carried out during the first 
months of the first year and planned the research program for the second 
year's study. 



VI 



In November 1979, an international conference was held in Brest 
sponsored by CNEXO. Investigators sponsored by the Joint NOAA/CNEXO 
Scientific Commission, as well as a number of other scientists, gave 
papers at this conference. The proceedings of this conference entitled 
" Amoco Cadiz : Fates and Effects of the Oil Spill" make a very good 
summary of the first one and one-half year study after the spill. 

Following the second meeting of the Joint Commission, Dr. Hess left 
NOAA and was replaced as co-chairman by Dr. Joseph W. Angelovic from the 
Office of Ocean Programs in NOAA. 

The third meeting of the Joint Commission was held in Paris, France, 
October 28, 1980, in conjunction with the meeting of the U.S. -French 
Cooperative Program in Oceanography. The previous work was reviewed and 
the final year of the research program was planned. 

Now the three-year study is over and attempts are being made to 
bring together the findings of the investigators. A workshop was held in 
Charleston, South Carolina, on September 17-18, 1981, to report on the 
physical and chemical studies. A second workshop was held in Brest, 
France, on October 28-30, 1981, to report on the biological effects 
studies. This document is the report of those workshops and forms the 
body of the final report to Amoco from the Joint NOAA/CNEXO Scientific 
Commission. 

Speaking for all who worked on the spill, we would like to thank the 
Amoco Transport Company for sponsoring this three-year study of the 
effects of the spill. Without Amoco 's help, we would be nowhere near our 
present state of knowledge of what the effects of the spill were or how 
the recovery back to normal conditions has proceeded. Other studies have 
been carried out, sponsored by the French Government and other sources, 
but an important part of the work has been sponsored by Amoco. 

Mr. Russ Mallatt, Dr. James Marum, Mr. John Lamping, Ms. Carol 
Cummings and others from Amoco attended meetings of the Joint Commission 
and the scientific sessions. They were always helpful and supportive of 
the Commission's work and never intruded on the design or conduct of the 
program. 

We have, through this cooperative effort, obtained more detailed and 
more useful knowledge of the effects of this oil spill than of any other 
large oil spill in history. A major reason for this is that the 
biological communities present before the spill had been studied in great 
detail by French scientists. 

Today many of the areas impacted by the spill appear to the casual 
observer to be recovered from the effects of the oil. However, investi- 
gations have shown that differences still exist between some of the 
current ecosystems and those present prior to the spill. Hopefully other 
studies will continue to watch and document the recovery processes. 



Vll 



These studies have added substantially to man's knowledge about oil 
spills. We can only hope that others will follow and build on the 
understanding of oil spill effects accumulated through these studies. 



Lucien Laubier 
Wilmot Hess 
Joseph Angelovic 



viii 



CNEXO-NOAA Joint Scientific Commission 

MEMBERSHIP 

L. Laubier, Cochairman 

Centre National pour l 1 Exploitation des Oceans 

Paris, FRANCE 

Wilmot N. Hess, Cochairman 

National Oceanic & Atmospheric Administration 

Boulder, Colorado 

Joseph W. Angelovic, Cochairman 
NOAA Office of Ocean Programs 
Rockville, Maryland 

Jack Anderson 

Battel le Pacific Northwest Laboratory 

Sequim, Washington 

J. Bergerard 
Station Biologique 
Roscoff, FRANCE 

Edward S. Gilfillan 
Bowdoin College 
Bowdoin, Maine 

I. R. Kaplan 

University of California, Los Angeles 

Los Angeles, California 

R. l.etaconnoux 

Institut des Peches Maritimes 

Nantes, FRANCE 

J. M. Peres 

Station Marine and Endoume 

Marseille, FRANCE 

Philippe Renault 

Institut Francais du Petrole 

Rueil Malmaison, FRANCE 

Douglas A. Wolfe 

NOAA Office of Marine Pollution Assessment 

Boulder, Colorado 



IX 



PART I 



Physical, Chemical, and Microbiological Studies 
After the AMOCO CADIZ Oil Spill 



Edited by E. R. Gundlach 

Research Planning Institute, Inc. 

Columbia, South Carolina, U.S.A. 29201 



MICROBIAL HYDROCARBON DEGRADATION WITHIN SEDIMENT 
IMPACTED BY THE AMOCO CADIZ OIL SPILL 



by 

Ronald M. Atlas 
Department of Biology 
University of Louisville 
Louisville, Kentucky 40292 



INTRODUCTION 



The wreck of the AMOCO CADIZ in March 1978 released over 210,000 
tons of oil into the marine environment. As much as one third of the 
spilt oil may have been washed into the intertidal zone. The spill 
occurred during storm surges, thereby spreading the oil throughout the 
intertidal zone. Two years after the AMOCO spill, the wreck of the 
tanker TANIO resulted in another oil spill that contaminated much of the 
same Brittany shoreline impacted by the AMOCO CADIZ. This study was 
undertaken to determine the fate of petroleum hydrocarbons within 
surface sediments along the Brittany coast with reference to the role of 
microorganisms in the oil weathering process. 



METHODS 



Sampling Regime 

Duplicate samples were collected at intertidal sites along the 
Brittany coast which had received varying degrees of oiling from the 
AMOCO CADIZ spillage (Fig. 1). The sampling sites included the salt 
marsh at lie Grande, a beach near Portsall in the vicinity of the wreck 
site, a mudflat in Aber Wrac'h, a beach at St-Michel-en-Greve near where 
a large bivalve kill had been reported, a relatively lightly oiled 
reference site at Trez Hir and a site at Tregastel which was not oiled 
by the AMOCO CADIZ spill, but was later oiled by the spill from the 
tanker TANIO (Table 1). Surface sediment samples (upper 5 cm) were 
collected with a 3 cm diameter soil corer. 

Samples were placed in metal cans for hydrocarbon analyses and in 
Whirlpak bags for microbial analyses. Samples were collected during 
December, 1978; March, 1979; August, 1979, November, 1979, March 1980, 
July, 1980 and June, 1981; 9, 12, 17, 20, 24, 28 and 39 months after the 
spillage, respectively. During November, 1979 sediment samples were 
also collected at four offshore sites in the Bay of Morlaix. 

Samples for microbiological analyses were processed within four 
hours of collection. For hydrocarbon analyses, samples were frozen and 
shipped to Energy Resources Company (ERCO) for extraction and analysis 



13 














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FIGURE 1. Location of intertidal and subtidal sampling sites. 



TABLE 1 - Description of sampling sites, 



Site 



Description 



1 lie Grande - sandy - low energy - NE of bridge - relatively 

unoiled. 

2 lie Grande - sandy - low energy - SW of bridge - near end of 

excavation area. 

3 lie Grande - soil - heavily oiled - amid Juncus - above 

excavation area. 

4 St-Michel-en-Greve - sandy - high energy - near low tide mark. 

5 Aber Wrac'h - mud - 100m offshore at Pcrros. 

6 Aber Wrac'h - mud - 200m offshore at Perros. 

7 Portsall - sandy - high energy - near wreck site - below high 

tide line. 

8 Portsall - sandy - high energy - near wreck site - rear rocks 

- 100m below high tide line. 

9 Trez Hir - sandy - moderate energy - reference site - below 

high tide. 

10 Trez Hir - sandy - moderate energy - reference site - 20m 

below high tide line. 

11 Tregastel - sandy - low energy - Tanio spill site - 20m below 

high tide line. 

12 Tregastel - sandy - low energy - Tanio spill site - 50m below 

high tide line. 



by silica gel column chromatography, weight determination, glass 
capillary gas chromatography and mass spectrometry. 

Enumeration of Microbial Populations 

Total numbers of microorganisms per gram dry weight of sediment 
were determined by direct count procedures. Portions of collected 
sediment samples were preserved with formalin. Microorgansims in the 
preserved samples were collected on a 0.2 mm pore size Nuclepore filter 
which had been stained with irgalan black. The microorganisms were 
stained with acridine orange and viewed using an Olympus epif luorescence 
microscope. Cells staining orange or green were counted in 20 randomly 
selected fields and the mean concentration determined. 

Hydrocarbon utilizing microorganisms were enumerated using a three 
tube Most Probable Number (MPN) procedure. Serial dilutions of sediment 
samples, prepared using Rila marine salts solutions, were inoculated 
into sealed serum vials containing 10 ml BushnjeAl Haas broth (Difco) and 
50 ml of Arabian crude oil spiked with C hexadecane (sp. act. 
1 mCi/ml) . After 14 days incubation at 15°C, the C0 2 (if any) in the 
head space was collected by flushing and trapping in oxifluor CO .and 
quantitated by liquid scintillation counting. Vials showing CO 
production (counts significantly above background) were scored as 
positive and the Most Probable Number of hydrocarbon utilizers per gram 
dry weight calculated from standard MPN tables. 

Biodegradation Potentials 

Portions of sediment samples were placed into serum vials 
containing 10 ml Bushnell Haas broth. and 50 ml light Arabian crude oil 
spiked with either., C hexadecane, C pristane, C naphthalene, C 
benzanthracene or C 9-methylanthracene. After 14 days incubation, 
microbial hydrocarbon degrading activities were stopped by addition of 
KOH. The " C0„ produced from mineralization of the radiolabelled 
hydrocarbon was determined by acidifying the solution, flushing the 
headspace, trapping the CO in oxifluor C0„ and quantitating the C 
by liquid scintillation counting. The residual undegraded hydrocarbons 
and biodegradation products were recovered by extraction with hexane. 
The L C in each solvent extract was determined and fractionated, using 
silica gel column chromatography, into undegraded hydrocarbon fractions 
(hexane + benzene eluates) and degradation product fractions (methanol 
eluate + residual non-eluted counts). A 0.75 cm diameter X 10 cm column 
packed with 70-230 mesh silca gel 60 was used. Radiolabelled material 
in each fraction was quantitated by liquid scintillation counting. 
Sterile controls were used to correct for efficiency of recovery and 
fractionation. Triplicate determinations were made for each sample and 
radiolabelled hydrocarbon substrate combination. The percent 
hydrocarbon mineralization was calculated as C0 2 produced (above 
sterile control)/ C hydrocarbon, added. The .percent hydrocarbon 
biodegradation was calculated as ' C0„ produced +, C methanol fraction 
+ C residual (all above sterile control)/ C hydrocarbon added. 
Carbon balances generally accounted for approximately 90% of the 
radiolabelled carbon added to the sediment (except for naphthalene where 
volatility losses prevented efficient recovery). 



Chemical Hydrocarbon Analyses Performed at ERCO 

For hydrocarbon analyses the samples were thawed, dried with 
methanol and extracted by high energy shaking with a mixture of 
methylene chloride-methanol (9:1). The extract was fractionated into an 
aliphatic (f ) fraction and an aromatic (f ) fraction using silica 
gel/alumina column chromatography. A 1 cm diameter X 25 cm column (1 cm 
alumina on top of 15 cm silica gel) was used. The f. fraction was 
eluted with 18 ml hexane; the f fraction subsequently was eluted with 
21 ml of a 1:1 mixture of hexane-methylene chloride. After reducing the 
volume of solvent by evaporation, the gross amount (weight) of 
hydrocarbon in each fraction was determined gravimetrically from an 
evaporated and dried aliquot of the extract. The extracts were 
subjected to quantitative glass capillary-gas chromatographic (GC) 
analysis. Selected aromatic fractions also were analysed by combined 
glass capillary gas chromatographic/mass spectrometric (GC/MS) analysis 
for qualitative identification of individual compounds and 
quantification of minor components. Participation in an 
intercalibration exercise under the direction of the National Analytical 
Laboratory indicated that these analyses were at the state^ of the art 
with repeatable ± 20% detection of hydrocarbons in the ng g dry weight 
sediment range. The details of GC and GC/MS analysis employed are as 
follows: 

CC: Hewlett Packard 5840A reporting GC with glass; splitless 
injection inlet system; 30 m glass capillary column coated with SE-30 (s 
100,000 theoretical plates); FID detector; temperature programmed at 
60-275°C min ; helium carrier gas 1 ml min ; transmission of 
integrated peak areas and retention time through HP 18846A digital 
communications interface to a PDP-10 computer for storage, retention 
index and concentration calculations. Deuterated anthracene (f.) and 
androstane (f ) were used as internal standards and response factors 
were determined with known concentrations of the reported compounds. GC 
analysis was used to quantitate components of the f. fraction. 

GC/MS: Hewlett Packard 5985 quadrapole system (GC/MS Computer); 
mass spectrometer conditions: ionization voltage=70 eV, electron 
multiplier voltage=2200 V, scan conditions 40 amu to 500 amu at 225 amu 
s~ . Quantification of components of the f fraction was accomplished 
by mass f ragraentography wherein the stored GC/MS data is scanned for 
parent ions (m ) . The tabulated total ion currents for each parent ion 
is compared with deuterated anthracene (internal standard) and an 
instrumental response factor applied. Authentic polynuclear aromatic 
hydrocarbon standards were used to determine relative response factors 
(when no standard was available a response factor was assigned by 
extrapolation) . 

In vitro Biodegradation 

Sediment was collected at sites 6 and 7 in November, 1979 for in 
vitro biodegradation experiments. Replicate one hundred gram portions 
of sediment were placed into 250 ml flasks to which 50 ml of a sterile 
solution containing 0.5% KNO + 0.5% KH 2 P0 4 and 0.5 ml of light Arabian 
crude oil were added. The flasks were agitated on a rotary shaker at 



100 RPM. After two, four, and six weeks of incubation at 15°C, the oil 
remaining in replicate flasks (two at each sampling time) was extracted 
and analysed as described below. 

Additionally, replicate 100 g portions of sediment were placed into 
1 liter stainless steel buckets. The containers were continuously 
flushed with a solution of Rila marine salts supplemented with 10 ppm 
KNO + 10 ppm KH PO . The height of the water level was adjusted to be 
3 cm above the surface of the sediment layer. The flow rate was 
adjusted to 10 ml/h. After two, four, and six weeks of incubation at 
15°C the oil remaining in replicate sediment portions was extracted and 
analysed as described below. 

Analyses of ^in vitro Experiments 

Residual oil was recovered from samples by extraction with 
sequential portions of diethyl ether and methylene chloride. The 
sediment was shaken at 200 RPM with repetitive portions of solvent. The 
extracts were subjected to column chromatography to split the extracts 
into aliphatic (f,) and aromatic (f~) fractions. Columns were prepared 
by suspending silica gel 100 (E. M. Reagents, Darmstadt, W. Germ.) in 
CH„C1„ and transferring the suspension into 25 ml burets with teflon 
stopcocks to attain a 15 ml silica gel bed. The CH„C1 ? was washed from 
the columns with three volumes of pentane. Portions of the extracts in 
pentane were applied to the columns, drained into the column bed, and 
allowed to stand for three to five minutes. The aliphatic fraction (f ) 
was eluted from the column with 25 ml pentane. After 25 ml pentane had 
been added to the column, 5 ml of 20% (v/v) CH„C1„ in pentane was added 
and allowed to drain into the column bed. Fraction f was 30 ml. The 
aromatic fraction (f ) was eluted from the column with 45 ml of 40% 
(v/v) CH 2 C1„ in pentane. 

The fractions of each extract were then concentrated to about 5 ml 
at 35°C and transferred quantitatively to clean glass vials. Fractions 
f. and f were prepared for analysis by gas chromatography or gas 
chromatography mass spectrometry. An internal standard, hexamethyl 
benzene (Aldrich Chem. Co., Milwaukee, WI.), was added to each sample. 
In fraction f . , hexamethyl benzene (HMB) was present at 12.6 ng/ml; in 
fraction f„, HMB was present at 25.2 ng/ml. 

Fraction f. was analyzed by GC on a Hewlett-Packard 5840 reporting 
GC with FID detector. The column was a 30 m, SE54 grade AA glass 
capillary (Supelco, Bellefonte, PA.). Conditions for chromatography 
were injector, 240°C; oven 70°C for 2 min. to 270°C at 4°C/min. and hold 
for 28 min.; FID, 300°C; and carrier, He at 25 cm/sec. A valley-valley 
intergration function was used for quantitative data acquisition. 
Response factors were calculated using n-alkanes, (C -C ) , pristane 
and phytane standards. 

Fraction f„ was analyzed with a Hewlett-Packard 5992A GC-MS. 
Conditions for chromatography were injector, 240°C; oven 70°C for 2 min. 
to 270°C at 4°C/min. and hold for 18 min. Data was acquired using a 
selected ion monitor program. Thirteen ions were selected for 
representative aromatic compounds. The ions monitored were 128, 142, 



147, 156, 170, 178, 184, 192, 198, 206, 212, 220, and 226. The 
representative compounds were naphthalene, methyl naphthalene, HMB as an 
interanal standard, dimethyl naphthalene, trimethyl naphthalene, 
phenanthrene, dibenzothiophene, methyl phenanthrene, methyl 
dibenzothiophene, dimethyl phenanthrene, dimethyl dibenzothiophene, 
trimethyl phenanthrene, and trimethyl dibenzothiophene, respectively. 
The dwell time per ion was 10 msec. Instrument response factors were 
calculated by injecting known quantities of unsubstituted and C and C„ 
substituted authentic aromatic hydrocarbons and determining the 
integrated response for each compound. These values were used to 
extrapolate for quantitation of isomers and C_ substituted compounds. 

For analysis of the polar fraction including microbial degradation 
products, three samples were selected for analysis by the University of 
New Orleans Center for Bio-organic Studies. The samples were: 1) flow 
through, 6 week incubation from site 6; 2) flow through, 6 week 
incubation from site 7; 3) agitated flask, 6 week incubation from site 
7. Frozen samples were sent for analysis. At the Center for 
Bio-organic Studies the samples were extracted with successive portions 
of CH OH, CH OH/CH CI and CH CI . The extracts were fractionated using 
silica gel and the f_ fraction was collected, methylated and analysed by 
high resolution GC-MS . 



RESULTS AND DISCUSSION 



The enumeration of hydrocarbon utilizing microorganisms indicated 
that numbers of hydrocarbon utilizers in the intertidal sediments 
increased significantly in response to hydrocarbon inputs (Table 2). 
Site 3, which is covered with seawater only at times of extreme high 
tide, showed very high populations of hydrocarbon utilizing 
microorganisms even three years after the AMOCO CADIZ spillage. Sites 5 
and 6 (located within Aber Wrac'h) and Sites 7 and 8 (located near 
Portsall) showed variable, but apparently elevated, numbers of 
hydrocarbon utilizers for up to two years following the spill. It 
appears that hydrocarbons contained within the mud sediments of Aber 
Wrac'h continued to exert a selective pressure on the microbial 
community that favored elevated populations of hydrocarbon utilizers for 
a longer period of time than sites on high-energy sand beaches. Site 2 
showed evidence that the TANIO spill impacted the lie Crande region. 
This site did not show elevated numbers of hydrocarbon utilizers in 
December 1978 or at later sampling times as a result of the AMOCO CADIZ 
spill, but in July of 1980, several months after the wreck of the TANIO, 
numbers of hydrocarbon utilizers were greatly elevated. A year later, 
however, the numbers of hydrocarbon utilizers had returned to background 
levels at this site. The unoiled control sites 9 and 10 and sites 1 and 
4, which were impacted by the AMOCO CADIZ spill, did not show any 
evidence of elevated hydrocarbon-utilizing populations during the 
sampling period. Similarly, the offshore sites A-D in the Bay of 
Morlaix did not appear to be elevated at the time of sampling in 
November 1979. Sites 11 and 12 were added following the wreck of the 
TANIO and showed obviously elevated populations of hydrocarbon utilizers 
that persisted for over a year. 



TABLE 2. MPN-Hydrocarbon Utilizers. 
,3 



Site 2-78 3-79 



(// X 10 /g dry wt.) 
8-79 11-79 3-80 



7-80 



6-81 



1 


0. 


2 


0.5 


1 


0.7 


5 


16 


1 


2 


5 




7 


1 


14 


30 


45000 


1 


3 


2200 


14000 


41000 


13000 


160000 


48000 


24000 


4 


2 




0.4 


2 


7 


1 


4 


5 


5 


8 




18 


8 


450 


19 


10 


15 


6 


9 




390 


20 


27 


190 


11 


17 


7 


40 




1900 


1 


2 


12 


2 


2 


8 


57 




350 


150 


8 


3 


1 


10 


9 


0. 


7 


0.4 


3 


1 


4 


1 


4 


10 


0. 


1 


0.2 


4 


1 


2 


2 


3 


11 


- 




- 


- 


- 


19000 


140000 


24000 


12 


- 




- 


- 


- 


920000 


140000 


24000 


A 


- 




- 


- 


66 


- 


- 


- 


B 


- 




- 


- 


32 


- 


- 


- 


C 


- 




- 


- 


13 


- 


- 


- 


D 


- 




- 


- 


13 


- 


- 


- 



The elevation in hydrocarbon utilizing populations, when detected, 
represented a shift within the microbial community. There generally was 
no evidence that total microbial biomass increased as a result of oiling 
although there generally was a tenfold variation in the microbial 
biomass between different sampling times (Table 3). 



Site 



12-78 



TABLE 3. Direct Count. 
(// X !0 8 /g dry wt.) 
3-79 8-79 11-79 3-80 



7-80 



6-81 



1 


3 


1 




4 


3 


1 


1 


3 


2 


4 


2 




16 


7 


3 


40 


2 


3 


10 


6 




220 


18 


24 


40 


38 


4 


2 


1 




3 


0.4 


0.5 


0.6 


2 


5 


3 


2 




19 


12 


17 


2 


15 


6 


6 


7 




150 


20 


27 


24 


26 


7 


3 


1 




8 


1 


1 


1 


2 


8 


1 


4 




1 


1 


2 


2 


4 


9 


1 


0. 


5 


2 


1 


0.3 


1 


4 


10 


0.5 


0. 


4 


13 


1 


0.4 


2 


7 


11 


- 


- 




- 


- 


5 


1 


4 


12 


- 


- 




- 


- 


39 


36 


40 


A 


- 


- 




- 


15 


- 


- 


- 


B 


- 


- 




- 


16 


- 


— 


_ 


C 


- 


- 




- 


3 


— 


_ 


_ 


D 


- 


- 




- 


10 


— 


_ 


_ 



The microbial hydrocarbon biodegradation potential measurements 
showed that following the AMOCO CADIZ oil spillage, indigenous microbial 
populations in the sediment at all sampling sites were capable of 
degrading both aliphatic and aromatic components of crude oil (Tables 
4-8). The variability in the results is not indicated in these tables, 
but the standard error was less than 4% for the percentage degraded and 
less than 10% for the percentage mineralized in all cases. The 
biodegradation potentials indicated that n-alkanes were preferentially 
degraded and that pristane was degraded at approximately half the rate 
of n-hexadecane. For aliphatic hydrocarbons approximately 30% of the 
amount of hydrocarbon biodegraded was converted to C0„ (mineralized) . 
Methodological difficulties in handling naphthalene made it difficult to 
assess the true extent of biodegradation for this compound. It is 
apparent, though, that the indigenous microbial populations were capable 
of degrading light aromatic hydrocarbons. The rates of degradation of 
the 3- and 4-ringed polynuclear aromatic hydrocarbons were lower than 
for branched and straight chained aliphatic hydrocarbons. In the case 
of the polynuclear aromatic hydrocarbons, a very low proportion of the 
amount of hydrocarbon degraded was converted to CO . 



TABLE 4. Hexadecane biodegradation showing % degraded and 
(% mineralized). 

Site 12-78 3-79 8-79 11-79 3-80 7-80 6-81 

1 40 41 21 17 10 25 17 



10 



(8) 


(11) 


(1) 


(15) 


(2) 


(12) 


(10) 


43 


38 


26 


22 


25 


19 


6 


(ID 


(13) 


(8) 


(13) 


(17) 


(12) 


(7) 


45 


46 


29 


23 


51 


19 


33 


(15) 


(15) 


(8) 


(18) 


(39) 


(14) 


(26) 


36 


48 


21 


25 


8 


26 


17 


(14) 


(13) 


(7) 


(14) 


(6) 


(19) 


(10) 


42 


46 


25 


35 


32 


24 


23 


(14) 


(14) 


(13) 


(14) 


(20) 


(18) 


(15) 


34 


47 


29 


26 


36 


18 


20 


(11) 


(12) 


(11) 


(20) 


(18) 


(11) 


(13) 


31 


45 


13 


31 


2 


20 


28 


(10) 


(13) 


(3) 


(21) 


(1) 


(14) 


(19) 


40 


43 


21 


35 


3 


17 


34 


(15) 


(11) 


(5) 


(19) 


(2) 


(12) 


(20) 


28 


32 


22 


35 


7 


27 


34 


(12) 


(3) 


(3) 


(14) 


(3) 


(15) 


(24) 


37 


30 


21 


45 


8 


22 


25 


(10) 


(3) 


(10) 


(32) 


(3) 


(14) 


(17) 



TABLE 5. Pristane biodegradation showing % degraded and 

(% mineralized). 



Site 12-78 3-79 



8-79 11-79 



3-80 



7-80 



6-81 



1 


18 


22 


12 


17 


18 


17 


27 




(3) 


(3) 


(1) 


(3) 


(2) 


(3) 


(3) 


2 


23 


22 


16 


15 


17 


24 


24 




(3) 


(4) 


(3) 


(5) 


(3) 


(3) 


(1) 


3 


19 


21 


16 


14 


18 


20 


24 




(2) 


(4) 


(3) 


(5) 


(5) 


(3) 


(6) 


4 


26 


23 


16 


18 


17 


19 


20 




(3) 


(4) 


(2) 


(4) 


(1) 


(3) 


(2) 


5 


21 


28 


21 


17 


16 


22 


25 




(3) 


(6) 


(4) 


(5) 


(4) 


(3) 


(6) 


6 


21 


30 


19 


19 


17 


20 


21 




(3) 


(6) 


(3) 


(5) 


(4) 


(4) 


(3) 


7 


25 


24 


16 


25 


12 


23 


23 




(3) 


(4) 


(1) 


(4) 


(1) 


(2) 


(4) 


8 


31 


23 


21 


18 


20 


21 


23 




(3) 


(4) 


(1) 


(5) 


(1) 


(2) 


(4) 


9 


27 


20 


22 


19 


17 


22 


24 




(3) 


(2) 


(1) 


(5) 


(2) 


(2) 


(7) 





29 


- 


21 


20 


18 


21 


20 




(2) 


(-) 


(3) 


(5) 


(2) 


(2) 


(8) 



TABLE 6. Biodegradation of naphthalene showing 
% degraded and (% mineralized). 



Site 



3-79 



8-79 



11-79 3-80 



1 


3(2) 


2(1 


I 3(31) 


KD 


2 


9(7) 


5(3 


) 2(2) 


2(2) 


3 


12(10) 


5(3 


> 2(2) 


6(6) 


4 


7(6) 


Kl 


) 5(5) 


KD 


5 


8(6) 


Id 


) 7(7) 


7(7) 


6 


11(10) 


Kl 


1 KD 


2(2) 


7 


10(9) 


1(1 


> 6(6) 


KD 


8 


9(7) 


1(1 


> 7(7) 


KD 


9 


HI) 


2(1] 


1 KD 


KD 





- 


2(1 


1 KD 


KD 



TABLE 7. Biodegradation of 9-methylanthracene showing 
% degradation and (% mineralization). 

Site 3-79 8-79 11-79 3-80 7-80 6-81 



1 


10 


- 


1 


5 


6 


9 




(0) 


(0) 


(0) 


(0) 


(0) 


(0) 


2 


19 


8 


6 


8 


10 


9 




(0) 


(0) 


(0) 


(0) 


(0) 


(0) 


3 


18 


18 


6 


7 


7 


10 




(0) 


(0) 


(0) 


(0) 


(0) 


(0) 


4 


23 


2 


2 


1 


10 


6 




(0) 


(0) 


(0) 


(0) 


(0) 


(0) 


5 


17 


4 


2 


7 


21 


6 




(0) 


(0) 


(0) 


(0) 


(0) 


(0) 


6 


19 


1 


3 


4 


11 


5 




(0) 


(0) 


(0) 


(0) 


(0) 


(0) 


7 


15 


7 


3 


2 


9 


5 




(0) 


(0) 


(0) 


(0) 


(0) 


(0) 


8 


21 


2 


4 


1 


6 


5 




(0) 


(0) 


(0) 


(0) 


(0) 


(0) 


9 


15 


11 


1 


4 


11 


4 




(0) 


(0) 


(0) 


(0) 


(0) 


(0) 





- 


6 


3 


13 


5 


4 




(-) 


(0) 


(0) 


(0) 


(0) 


(0) 



TABLE 8. Biodegradation of benzanthracene showing 
% degradation and (% mineralization). 

Site 12-78 3-79 8-79 11-79 3-80 7-80 6-81 

1 5 21 18 2 5 10 13 



10 



(0) 


(0) 


(0) 


(0) 


(0) 


(0) 


(0) 


8 


17 


10 


- 


4 


2 


6 


(0) 


(0) 


(0) 


(0) 


(0) 


(0) 


(0) 


11 


15 


7 


7 


8 


2 


12 


(0) 


(0) 


(0) 


(-) 


(0) 


(0) 


(0) 


4 


5 


6 


2 


6 


3 


5 


(0) 


(0) 


(0) 


(0) 


(0) 


(0) 


(0) 


8 


13 


14 


2 


10 


11 


8 


(0) 


(0) 


(0) 


(0) 


(0) 


(0) 


(0) 


4 


8 


11 


2 


4 


1 


6 


(0) 


(0) 


(0) 


(0) 


(0) 


(0) 


(0) 


11 


3 


6 


7 


4 


3 


6 


(0) 


(0) 


(0) 


(0) 


(0) 


(0) 


(0) 


6 


5 


5 


4 


1 


7 


4 


(0) 


(0) 


(0) 


(0) 


(0) 


(0) 


(0) 


2 


8 


5 


7 


2 


13 


5 


(0) 


(0) 


(0) 


(0) 


(0) 


(0) 


(0) 


1 


- 


14 


8 


11 


12 


4 


(0) 


(-) 


(0) 


(0) 


(0) 


(0) 


(0) 



10 



Based on the changes in the composition of the microbial community, 
as evidenced by elevations in numbers of hydrocarbon utilizing 
microorganisms and based on the microbial biodegradation potentials, it 
can be stated that biodegradation appears to have been a very important 
process that had the potential for significantly altering the 
composition of the hydrocarbon mixture that impacted the sediments of 
the Brittany Coast following the AMOCO CADIZ spill. With time the 
residual hydrocarbon mixture should contain increasingly high 
proportions of complexed branched and condensed-ring hydrocarbon 
compounds that are degraded relatively slowly by the indigenous 
microorganisms . 

The weight of the extractable hydrocarbons confirmed the occurrence 
of contaminating hydrocarbons at site 2 in July 1980, presumably as a 
result of the TANIO spillage (Table 9). Similarly, high concentrations 
of hydrocarbons were found in at Sites 11 and 12 which were closer to 
the TANIO wreck. The levels of hydrocarbons at Site 3 remained high 
throughout the sampling program. Sites 1, 4, 9, and 10 showed a general 
lack of significant hydrocarbon concentration that would be indicative 
of petroleum pollution. Sites 5, 6, 7, and 8, in contrast, showed 
somewhat elevated hydrocarbon concentrations. 

TABLE 9. Weights of extractable hydrocarbons (ug/g) . 
Site 12-78 3-79 8-79 11-79 3-80 7-80 6-81 

3 h 

4 E' 

2 

5 ' 

2 
6 f . 



1 i\ 



27 


9 


5 


17 


8 


20 


4 


57 


5 


16 


58 


37 


25 


22 


52 


21 


42 


147 


50 


2370 


9 


53 


11 


47 


136 


50 


2160 


29 


272 


2232 


121092 


108000 


33000 


16600 


3680 


338 


2537 


70329 


95833 


22500 


32400 


8080 


21 


22 


9 


20 


35 


12 


8 


57 


17 


11 


19 


29 


17 


49 


122 


140 


56 


213 


65 


68 


21 


103 


82 


99 


233 


73 


156 


42 


178 


458 


177 


536 


874 


109 


56 


226 


416 


209 


556 


830 


281 


75 


91 


72 


152 


80 


58 


23 


15 


75 


59 


123 


63 


39 


26 


29 


179 


382 


164 


243 


98 


34 


31 


148 


298 


135 


194 


83 


24 


59 


7 


32 


77 


20 


21 


43 


13 


3 


34 


78 


32 


21 


36 


25 


8 


29 


13 


36 


23 


23 


21 


11 


20 


29 


96 


31 


48 


74 


- 


- 


- 


- 


515000 


60800 


320 


- 


- 


- 


- 


512000 


36300 


440 


- 


- 


- 


- 


- 


73200 


67 


- 


- 


- 


- 


- 


14300 


109 



2 
10 f 

2 

12 f l 

r 2 
A f , - - 102 

t - - - 88 

B f , - - - 210 

f* - - - 210 

C f - 13 

f - - - 21 

D f - 21 

t\ - - 10 



11 



The detailed gas-chromatographic and mass-spectral analyses of the 
samples collected at each site indicated a lack of significant petroleum 
hydrocarbons throughout the study at Sites 1, 4, 9, and 10 (Tables 10, 
13, 18, 19). Site 2 showed some evidence of weathered hydrocarbons in 

1978 and a significant input of fresh petroleum hydrocarbons in July 
1980 (Table 11). Site 3 had significant concentrations of weathered 
petroleum origin throughout the study (Table 12). Sites 5 and 6 showed 
an alteration of the hydrocarbon mixture with time that indicated the 
occurrence of biodegradation (Tables 14, 15). Samples at Sites 7 and 8 
continued to show the presence of a relatively unweathered hydrocarbon 
mixture up to two years following the AMOCO CADIZ spill (Tables 16, 17). 
It appears that undegraded hydrocarbons were seeping into the surface 
sediments at Site 8 and it is postulated that either shifts in the 
sediment were repeatedly exposing hydrocarbons that had been protected 
from microbial degradation and/or that some oil continued to be washed 
ashore from the sunken AMOCO CADIZ vessel. Site 11 showed clear 
evidence of heavy oiling from the TANIO spill which persisted for a year 
following the spill (Table 20) . The offshore sites sampled in November 

1979 in the Bay of Morlaix failed to show the presence of AMOCO CADIZ 
oil. 



TABLE 10. Hydrocarbon concentration ng/g. 
SITE 1 
C-# 12-78 3-79 8-79 11-79 3-80 7-80 6-81 



14 








1 


2 





- 


2 


15 


20 





125 


250 


23 


1 


123 


16 


2 





14 


12 


3 


3 


9 


17 


65 


15 


438 


86 


156 


5 


91 


pristane 


62 


22 


27 


76 


43 


30 


102 


18 


3 


2 


3 


5 


8 


4 


10 


phy tane 


11 


2 


2 


5 


6 


3 


2 


19 





2 


2 


3 


7 


3 


5 


20 


5 


2 


2 


4 


7 


3 


4 


21 


6 


1 


3 


4 


8 


2 


7 


22 


6 


2 


3 


4 


8 


3 


9 


23 


9 


2 


4 


6 


9 


5 


18 


24 


9 


2 


3 


5 


8 


2 


24 


25 


17 


2 


5 


14 


9 


13 


34 


26 


8 


2 


2 


2 


6 


3 


28 


27 


10 


I 


4 


10 


7 


6 


35 


28 


7 


1 


1 


2 


5 


2 


21 


29 


18 


5 


6 


10 


10 


18 


38 


30 


8 


1 


7 


6 


3 


4 


35 


alkanes: 


1.2 


0.9 


20.0 


2.3 


5.6 


6.0 


2.3 


isoprenoids 
















pristane: 


5.6 


7.8 


13.5 


- 


7.3 


1.6 


50.0 


phytane 

















12 



TABLE 11. Hydrocarbon concentration ng/g , 



SITE 2 



c-# 


12-78 


3-79 


8-79 


11-79 


3-80 


7-80 


6-81 


14 





3 


6 








11700 


3 


15 


44 


115 


331 


154 


39 


18200 


111 


16 





11 


18 





4 


19800 


11 


17 


65 


40 


169 


68 


18 


22000 


93 


pristane 


27 


38 


160 


1100 


6 


19800 


46 


18 


8 


9 


8 


181 


5 


22600 


10 


phvcane 


17 


126 


32 


151 


15 


25900 


15 


19' 


30 


26 


5 


35 


2 


23400 


6 


20 


18 


16 


9 


9 


8 


18600 


9 


21 


14 


40 


18 


15 


5 


16700 


13 


22 


16 


29 


7 


10 


9 


12800 


14 


23 


14 


11 


8 


38 


8 


10900 


23 


24 


12 


11 


7 


6 


13 


10000 


22 


25 


45 


70 


30 


64 


146 


7120 


35 


26 


22 


12 


6 


10 


16 


6450 


30 


27 


34 


15 


23 


36 


24 


6320 


33 


28 


53 


40 


6 


29 


10 


4780 


15 


29 


51 


47 


9 


39 


53 


6040 


36 


30 


31 


95 


71 


116 


55 


4380 


20 


alkanes: 


_ 


1.5 


2.5 


0.3 


3.2 


1.3 


3.5 


isoprenoids 
















pristane: 


0.4 


0.8 


5.1 


7.3 


0.4 


0.8 


3.0 


phytane 
















TABLE 12. 


Hydrocarbon conce 


intration ng/g. 










SITE 3 








C-tf 


12-78 


3-79 


8-79 


11-79 


3-80 


7-80 


6-81 


14 


19 


_ 


3525 


1040 


1390 


- 


- 


15 


- 


- 


1 1025 





633 


- 


- 


16 


17 


121 


9350 





400 


- 


- 


17 


32 


12 


9550 


3440 


200 


- 


- 


pristane 


213 


809 


145150 


47900 


104 


- 


- 


18 


48 


86 


20250 


3600 


106 


- 


- 


phytane 


985 


3088 


275900 


130000 


673 


- 


- 


19 


255 


948 


63075 


29200 


283 


825 


- 


20 


149 


247 


36000 


11900 





- 


1270 


21 


31 


24 1 


17975 


6210 


508 


2103 


2380 


22 


25 


12 


8875 


1440 


130 


- 


3050 


23 


38 


56 


11100 








- 


3280 


24 


54 


48 


7925 


3510 





- 


4640 


25 


_ 


- 


12600 


21300 


2340 


- 


5700 


26 


_ 


160 


14900 


2540 


329 


- 


5190 


27 


172 


898 


45250 





1160 


516 


10800 


28 


81 


934 


18600 





109 


- 


2460 


29 


41 


2025 


31250 


2090 


3330 


1692 


12120 


30 


- 


400 


75775 





118 


13900 


3120 


alkanes: 


0. 1 


_ 


0. 1 


0.1 


0.8 


- 


- 


isoprenoids 
















pristane: 


0.5 


0.3 


0.5 


0.4 


0.2 


- 


1.9 


phytane 

















13 



TABLE 13. Hydrocarbon concentration ng/g . 

SITE 4 



C-D 



12-78 3-79 



8-79 



1 1-79 



3-80 



7-80 



6-81 



14 














- 


1 


i 


15 





-> 








3 


13 


8 


16 





2 








5 


8 


7 


17 


18 


4 


4 


4 


12 


15 


8 


pristane 


60 


6 





2 


3 


4 


3 


18 


37 


3 


C 


2 


10 


6 


8 


phvtane 


153 


18 





8 


8 


6 


11 


19" 


b8 


9 


2 


5 


9 


7 


6 


20 


37 


10 


2 


3 


8 


7 


6 


21 


30 


8 


4 


4 


12 


5 


9 


22 


21 


5 


1 


3 


7 


1 


8 


23 


27 


6 


2 


6 


8 


7 


17 


24 


20 


4 





3 


5 


3 


17 


25 


23 


6 


1 


3 


14 


3 


27 


26 


42 


7 





3 


4 


6 


16 


27 


37 


7 


10 


7 


17 


11 


48 


28 


60 


9 


3 


3 


3 


3 


7 


29 


47 


19 


9 


18 


28 


22 


61 


30 


43 


1 


30 


1 


50 


2 


12 


alkanes : 


0.2 


0.7 


_ 


0.6 


2.8 


4.1 


2.3 


isoprenoids 
















pristane: 


0.4 


0.4 


_ 


_ 


0.4 


0.6 


0.3 


phytane 

















TABLE 14. Hydrocarbon concentration ng/g. 

SITE 5 



C-lt 


12-78 


3-79 


8-79 


11-79 


3-80 


7-80 


6-81 


14 


19 


37 


2 


16 


- 


5 


3 


15 


20 


65 


167 


59 


1 1 


35 


29 


16 


- 


- 


18 





- 


12 


8 


17 


25 


1 12 


122 





95 


18 


585 


pristane 


24 


150 


11 


885 


8 


175 


108 


18 


16 


50 


17 





4 


2 


4 


phvtane 


158 


293 


43 


158 


12 


36 


20 


19' 


64 


140 


12 


16 


4 


3 


8 


20 


43 


5 


17 


19 


16 


7 


9 


21 


57 


50 


23 


208 


8 


13 


17 


2 2 


39 


18 


19 


14 


6 


18 


1 1 


23 


25 


36 


23 


30 


20 


18 


20 


24 


4 


30 


15 


18 


9 


13 


20 


25 


22 


5 


39 


115 


99 


111 


100 


26 


46 


5 


11 


24 


21 


11 


21 


27 


51 


93 


30 


87 


48 


29 


62 


28 


70 


64 


6 


13 


7 


13 


10 


29 


96 


',36 


17 


113 


130 


86 


122 


30 


17 


57 


80 


10 


20 





23 



alkanes: 0. 3 
isoprenoids 



pristane: 
phy tane 



0.2 



0.5 



0.5 



5. 1 



0.3 



0.3 



12.0 



5.5 



2.7 



0.7 



4.4 



5.4 



14 



TABLE 15. Hydrocarbon concentration ng/g. 

SITE 6 



C-ll 


12-78 


3-79 


8-79 


11-79 


3-80 


7-80 


6-81 


14 


_ 


82 





10 


_ 


4 


T 


15 


8 


61 


28 


111 


68 


28 


30 


16 


- 


- 








- 


9 


9 


17 


23 


1 17 


14 


164 


200 


6 


101 


pristane 


102 


125 


15 


71 


70 





12 


18 


- 


8 





28 


- 


6 


7 


phy tane 


360 


489 


135 


289 


225 


23 


i n 


19 


101 


121 


20 


20 


- 





15 


20 


35 


12 





42 


- 


2 


10 


?1 


86 


180 


59 


223 


35 


31 


30 


22 


- 


149 


4 


48 


38 


9 


6 


23 


39 


58 


16 


81 


80 


28 


61 


24 


5 


- 


5 


37 


27 


5 


10 


25 


109 


159 


80 


128 


484 


47 


85 


26 


128 


151 


10 


50 


53 


6 


30 


27 


68 


126 


88 


135 


255 


48 


124 


28 


97 


56 


13 


105 


28 


12 


21 


29 


159 


319 


55 


200 


590 


122 


245 


30 


36 


140 


254 


342 


30 


18 


55 



alkanes: 0.1 0.3 0.2 0.8 0.9 1.5 2.7 
isoprenoids 

pristane: 0.3 0.3 0.1 0.3 - 0.0 0.5 
phytane 



TABLE 16. Hydrocarbon concentration ng/g. 

site 7 

C-lt 12-78 3-79 8-79 11-79 3-80 7-80 6-81 



14 


9 


4 


9 





1 


14 


43 


15 


7 


7 


43 


11 


11 


29 


77 


16 


51 


10 


58 


18 


32 


29 


64 


17 


109 


20 


96 


27 


63 


38 


85 


p r i s t .1 n e 


154 


24 


102 


25 


47 


35 


7 


18 


121 


33 


113 


36 


39 


41 


64 


phvtnne 


256 


65 


159 


43 


86 


43 


39 


19 


54 


46 


139 


55 


44 


47 


65 


20 


122 


36 


124 


23 


56 


35 


67 


21 


83 


25 


106 


30 


49 


29 


42 


22 


108 


24 


94 


30 


58 





45 


23 


84 


23 


86 


28 


59 


24 


43 


24 


61 


18 


80 


46 


47 


24 


54 


25 


1 1 1 


27 


89 


42 


62 


25 


32 


26 


105 


27 


62 


25 


42 


22 


35 


27 


54 


20 


110 


48 


30 


17 


35 


28 


126 


42 


52 


15 


28 


14 


17 


29 


92 


28 


62 


28 


49 


26 


44 


30 


1 12 


36 


356 


152 


29 


37 


29 



nlkanes: 0.6 0.7 1.0 1.4 1.1 1.6 3.3 

isoprenoids 

pristane: 0.6 0.4 0.6 0.6 0.6 0.8 0.2 

phytane 



15 



TABLE 17. Hydrocarbon concentration ng/g. 

SITE 8 

C-« 12-7S 3-79 8-79 11-79 3-80 7-80 6-81 

24-8 12 
73 7 21 80 

29 
64 
108 
40 
46 
42 
29 
27 
30 
36 
21 
25 
28 
22 
11 
33 
10 218 14 29 



alkanes: 0.7 0.3 1.1 1.1 1.0 1.1 1.2 
isoprenoids 

pristane: 0.5 0.4 0.8 0.8 0.6 0.7 2.3 
phytane 



TABLE 18. Hydrocarbon concentration ng/g. 

SITE 9 
C-ll 12-78 3-79 8-79 11-79 3-80 7-80 6-81 



14 


160 


34 


16 


15 


368 


77 


66 


16 


518 


87 


47 


17 


640 


113 


80 


pristane 


941 


427 


98 


18 


818 


219 


70 


phytane 


1839 


955 


116 


19 


112? 


352 


85 


20 


849 


203 


81 


21 


530 


121 


62 


22 


430 


135 


50 


23 


314 


85 


47 


24 


272 


85 


42 


25 


54 


190 


52 


26 


489 


234 


33 


27 


328 


197 


71 


28 


431 


292 


24 


29 


362 


326 


15 


30 


315 


411 


170 



73 


22 


23 


104 


44 


31 


135 


41 


38 


108 


50 


34 


171 


74 


54 


158 


57 


54 


97 


51 


35 


66 


44 


28 


64 


38 


24 


59 


34 


32 


68 


30 


43 


42 


56 


18 


46 


28 


19 


31 


26 


41 


19 


11 


12 


30 


63 


27 



14 














- 


28 


- 


15 








3 


8 


- 


42 


- 


16 








3 


3 


- 


21 


- 


17 


3 


11 


5 


22 


8 


36 


19 


pristane 


1 


4 


6 


2 


- 





1 


18 


3 


6 


3 


5 


6 


9 


9 


phytane 


2 


4 


L 


3 


- 





5 


19 


4 


3 


4 


4 


8 


6 


12 


20 


4 


3 





6 


11 


6 


12 


21 


4 


6 


4 


6 


11 


4 


15 


22 


4 


7 


3 


5 


9 


6 


12 


23 


4 


9 


3 


10 


8 


7 


19 


24 


4 


e 


2 


5 


4 


4 


15 


25 


"7 


13 


8 


15 


7 


62 


29 


26 


8 


23 


1 


3 


1 


2 


15 


27 


8 


12 


3 


11 


3 


14 


44 


28 


11 


34 





3 


1 





12 


29 


11 


22 





12 


15 


24 


65 


30 


6 


8 


13 


1 


1 


3 


25 



alkanes: 1.8 2.0 1.6 7.1 - - 5.7 
isoprenoids 

pristane: 0.6 0.2 2.6 0.9 - 
phytane 



16 





TABLE 19 


Hydrocarb 


on concentration 


ng/q. 










SITE 10 








c-# 


12-78 


3-79 


8-79 




11-79 


3-80 


7-80 


6-81 


1A 





1 


2 




_ 


_ 


25 


7 


15 





5 


33 




3 


- 


A2 


7A7 


16 


1 


5 


29 




3 


- 


19 


17 


17 


3 


11 


53 




1A 


8 


Al 


228 


pristane 


1 


3 


7 




3 


- 


7 


A 


18 


3 


7 


9 




10 


A 


8 


10 


pliytane 


2 





A 




2 


- 


2 


5 


19 


3 


11 


5 




6 


1 


7 


11 


20 


A 


8 


A 




6 


3 


6 


8 


21 


3 


A 


5 




6 


A 


2A6 


1A 


22 


2 


10 


5 




5 


3 


6 


15 


23 


2 


8 


7 




7 


A 


10 


31 


2A 


1 


A 


5 




5 


9 


1 


21 


25 


3 


lib 


13 




2A 


7 


55 


76 


26 


2 


13 


6 




7 


2 


2 


33 


27 


1 


11 


1 1 




21 


5 


31 


137 


28 


1 


11 


8 




7 


5 


7 


23 


29 





5 


38 




33 


1A 


53 


19A 


30 





3 


23 




3 


- 


A 


3A 



alkanes: 1.9 - 9.0 - - A.O 63.6 
isoprenoids 

pristar.e: 0.5 - 1.9 - - 3.5 0.8 
phytane 



TABLE 20. Hydrocarbon concentration ng/g. 



C-» 3-80 7-80 6-81 

IA 605000 73200 69 

15 661000 88200 285 

16 625000 89100 83 

17 636000 93600 110 
pristane 3A2000 66900 A18 

18 6A3000 110700 76 
phytane 231000 53A00 372 

19 629000 129000 80 

20 680000 142000 128 

21 72AC00 132000 122 

22 719000 1A1000 IA1 

23 719000 1A2000 196 
2A 72A000 1A0000 209 

25 685000 133000 202 

26 718000 155000 22A 

27 669000 167000 207 

28 62/000 192000 108 

29 620000 168000 152 
?0 A79000 190000 318 



Alkanes: Isoprenoids 0.2 2. A 0.3 

Pristane:Phytane 0.7 1.3 1.1 



17 



The significant features of the chemical changes that were observed 
included a marked decrease in the proportion of n-alkanes relative to 
isoprenoid hydrocarbons, the transient occurrence of an increase in 
unresolved hydrocarbons within the first year following the AMOCO CADIZ 
spillage, and the decreased importance of unsubstituted polynuclear 
aromatic hydrocarbons relative to dibenzothiophenes and the comparable 
or substituted forms of the polynuclear aromatic hydrocarbons (Figs. 2 
and 3). 

The In vitro hydrocarbon biodegradation experiments confirmed the 
fact that the indigenous microbial populations were capable of rapid and 
extensive degradation of Arabian crude oil. Much greater rates of 
biodegradation were observed in agitated compared to flow through 
experiments (Figs. 4-9). Both the in vitro experiments and the analysis 
of field experiments support the hypothesis that mixing energy has a 
very significant effect on the rates of hydrocarbon biodegradation. 
Rates of biodegradation appear to be environmentally influenced by the 
turbulence of mixing which can ensure a continued supply of nutrients 
and oxygen as well as dispersing the oil so as to establish a favor- 
able surface area to volume ratio for rapid microbial hydrocarbon 
biodegradation. The similarity of changes, observed in the composition 
of the hydrocarbon mixture i_n vitro compared to the analysis of field 
samples also suggests that nutrients were not a limiting factor that 
determined the rates of hydrocarbon biodegradation. 

The analysis of the polar fractions from the iri vitro experiments 
showed some surprising results (Table 21). There was a lack of 
oxygenated aromatic compounds. It had been predicted that there would 
be a greater accumulation of polar products from aromatic biodegradation 
since less CO was being produced than from aliphatic biodegradation 
where a significant proportion of the hydrocarbon that was biodegraded 
was released as CO . There were significant accumulations of polar 
compounds that appear to be biodegradation products of aliphatic 
hydrocarbons, especially as C.,-C „ acids. Interestingly, the major 
polar products included unsaturated acids. As a rule, the predominant 
biochemical pathway for the biodegradation of straight chained 
hydrocarbons does not involve the formation of unsaturated compounds, 
although a biochemical pathway has recently been elucidated for some 
bacteria that does introduce a double bond into the hydrocarbon. It 
appears that the microbial populations indigenous to the sediment of the 
Brittany Coast possess such a biochemical capability. 



18 



TTTl n rrffl 



KMIIMCi WOU^I 



! 



I 



.Dm. 




FIGURE 2. Changes in the relative concentrations of aliphatic hydrocarbons 
at sites 3, 5, and 7. 



19 



r rtnrert y renranrrnrrr 



-t ■ <t'B 



MM 



■n- 



JX 



[B.rtlJ,kr T 



L rTh , 



— nJL? 



J 



iffl 



ram 



UtU 



n d 



_d 



POBTS*LL 
NOVEMBER "->"* 



Q. 



«rt(" W«*CH 

NOvCWBER >'9 



JL 



HE '.H»NCJf 

NOVEMBER 19'9 



nn J 



NCCCCPCCCCDCCC NCCCCpCCCCOCCC nccccpccccdccc 

1234 1234 1J3 1JJ* 1 J 3 4 1 I J l J 3 « i 2 3 4 « 2 3 

N4PHTHA PHENAN DIBENiO NAPNtHA PhENAN OlBEN/O NAPHTHA PhENAN 0«BENJO 

1 t NE fMHENE fMiQPMENE iCHt TmRENE ImiOPmENC LENC 



MRENE THlOPHENE 



FIGURE 3. Changes in the relative concentrations of aromatic hydrocarbons 
at sites 3, 5, and 7. 



20 



5- 



3- 






o 

z 

o 

UJ 
>4 



UJ - 

cc 



FLOW THROUGH 
2 WEEKS 
SITE 7 



■ I 



2- 



FLOW THROUGH 
6 WEEKS 
SITE 7 



ll 



- 3 



FLOW THROUGH 
2 WEEKS 
SITE 6 



ll 



4 WEEKS 
SITE 6 



ll 



II 1213 14 15I6WPRI8PHI9 20 21 22232425262/28 



M 1? 1.1 14 IS lb i; PR 18 PH 19 20 21 22 23 24 25 26 2/ 28 



FIGURE 4. (Lett column) Changes in the reLative concent rations of aliphatic 
hydrocarbons in f low-through experiment with sediment from site 7, 



FIGURE 5. (Right column) Changes in the relative concentrations of aliphatic 
hydrocarbons in f Low- through experiment with sediment from site 6. 



21 



< 

cr 



O 





FLOW THROUGH 


3 - 


SITE 6 




2 WEEKS 


2- 


























1 











o 
o i-| 



N C,C, CjP C,C 2 C 3 D C,C ? C 3 
NNN PPPBDDD 

T B B B 
T T T 







1 r 




4 WEEKS 
1 



n 



r- 






6 WEEKS 


< 3- 

_l 








111 

K 2 " 










1 - 


r 


f 


-r-Th 





FLASK 
TIME 
SITE 7 



a. 



rmd] 



rT"rfTTtf^ 



J 



II 12 13 14 IS 16 w PR 18 PM 19 20 21 7 2 23 24 25 26 2 7 28 



FIGURE 6. (Left column) Changes in the relative concentrations of aromatic 

hydrocarbons in flow-through experiment with sediment from site 6, 



FIGURE 7. (Right column) Changes in the relative concentrations of aliphatic 
hydrocarbons in flask experiment with sediment from site 7. 



22 



4. 



3_ 



2- 

z 
o 

t- 1 _ 

< 

K 



FLASK 
O TIME 
SITE 6 



Ul 



o 

z 

o 1_ 
o 



2 WEEKS 



£1 



on 



12 1 
□ 



FLASK 
SITE 6 



JJ 



Mi-m-L 



1_ 



4 WEEKS 



i I I n-i-n-r-i 



idl 



jD 



Ha 



5.1 



n 

4ppml 



_d 



i. 



j 



6 WEEKS 



x£H 



11 12 13 14 15 16 17 PR 18 Ph 19 20 21 22 23 24 25 26 27 28 



N C,C, CjP C,C, C,D C, C,C, F C, 
NNN PPPBDDD F 

T B B B 

TIT 



FIGURE 8. (Left column) Changes in the relative concentrations of aliphatic 
hydrocarbons in flask experiment with sediment from site 6. 

FIGURE 9. (Right column) Changes in the relative concentrations of aromatic 
hydrocarbons in flask experiment with sediment from site 6. 



23 



TABLE 21. Concentrations and Identities of Polar Compounds ng/g 



SITE SITE SITE 

7 6 7 
FLASK FLOW FLOW 
THROUGH THROUGH 



dodecanoic acid 
tetradecanoic acid 
methyltetradecanoic acid 
pentadecanoic acid 
hadecenoic acid 
hexadecanoic acid 
isoheptadecanoic acid 
heptadecanoic acid 
octadecenoic acid 
octadecanoic acid 
nonadecanoic acid 
eicosanoic acid 
tetracosanic acid 
hexacosanic acid 
octacosanic acid 



16.5 


2.3 


4.7 


22.2 


13.7 


24.5 


15.0 


19.7 


43.3 


10.5 


13.5 


24.0 


47.0 


129.0 


217.0 


73.9 


109.0 


157.0 


8.3 


7.8 


11.9 


3.2 


8.6 


4.3 


59.3 


76.4 


99.2 


44.4 


34.2 


44.6 


10.1 


25.4 


- 


9.8 


25.4 


55.8 


14.5 


3.0 


13.8 


7.7 


1.4 


10.8 


15.8 


13.3 


15.6 



isocyclopropaneoctanoic acid 

methyloctahydrophenanthrene- 
carboxylic acid (tent.) 



15.5 25.5 42.2 
21.3 2.0 



24 



CONCLUSIONS 



Microbial degradation appears to have played a very important role 
in the weathering of oil spilled from the AMOCO CADIZ. Microbial 
hydrocarbon degradation potentials are in general agreement with the 
observed changes in the composition of oil stranded within the littoral 
zone. The chemical evolution of the hydrocarbon mixture within 
intertidal sediments led to a relative enrichment in isoprenoid alkanes, 
a transient complex unresolved mixture, and a relative enrichment of 
dibenzothiophenes and alkylated phenanthrenes. 

There was a general, but variable decline in concentrations of 
hydrocarbons over the three year period following the AMOCO CADIZ spill 
within Aber Wrac'h. The concentrations of hydrocarbons also declined at 
sites that were regularly covered by tides. At the one site in lie 
Grande, which is not subject to daily tidal washing, the concentrations 
of hydrocarbons remained high even three years following the spill. At 
nearby sites within the lie Grande salt marsh, which were physically 
cleansed of AMOCO CADIZ oil, there was little chemical or microbial 
evidence of any impact from the AMOCO CADIZ spill at any of the sampling 
times. The incurrence of oil from the TANIO wreck was apparent even at 
sites that had been oiled as a result of the AMOCO CADIZ spill. 

The microbial population levels generally reflected the relative 
degrees of persistence of petroleum hydrocarbons. The microbial 
community at all of the sites studied had essentially the same potential 
capability for degrading hydrocarbons and as such the differences in the 
hydrocarbon concentrations and composition recovered from the field 
samples probably reflect the initial rates of oiling and environmental 
influences. The indigenous microbial community retained the capability 
of responding to a second incursion of oil resulting from the TANIO 
spill. 

Both the field experiments and the i_n vitro studies suggest that 
mixing energy, related to nutrient and oxygen availability, was 
extremely important in permitting the high rates of observed oil 
weathering. The occurrence of both saturated and unsaturated acids in 
the sediments studied in vitro suggest that several biochemical pathways 
were active in the biodegradation of the aliphatic hydrocarbon fraction. 
The hydrocarbon biodegradation potential suggested that relatively high 
concentrations of oxygenated aromatic hydrocarbons should accumulate, 
but for unexplained reasons the analyses of the polar fraction generally 
failed to show such accumulations. 



25 



LABORATORY SIMULATION OF THE 

MICROBIOLOGICAL DEGRADATION OF CRUDE OIL 

IN A MARINE ENVIRONMENT 

by 

D. Ballerini(l) , J. Ducreux(l) and J. Riviere(2) 

(1) Institut Francais du Petrole - Direction de Recherche 
"Environnement et Biologie Petroliere" 

1 et 4 avenue de Bois-Preau - 92506 RUEIL-MALMAISON - FRANCE 

(2) Institut National Agronomique, Paris-Grignon 

16, rue Claude Bernard - 75231 PARIS 05 - FRANCE 



This study essentially intends to quantify the biodegradation 
process of a crude oil in optimum conditions compatible with the 
marine environment. 

Experiments were conducted in the Laboratory reactors (batch and 
continuous cultures), with perfect monitoring of all physicochemical 
parameters such as pH (pH 8.1), temperature at 20°C, mixing rate 
600 rpm, and aeration velocity (1 liter of air/liter of medium 
per hour) . 

The composition of the mineral medium was defined by taking the 

mean composition of salts in the Atlantic Ocean as a basis, and 

enriching it with nitrogen (235 mg.1-1), phosphorus (26.7 mg. 
1-1) and iron (0.4 mg.1-1). 

In order to reproduce conditions prevailing at sea as closely 
as possible, in which the evaporation of light products is not 
negligible Arabian Light Crude was employed (ALC 240+) from which 
all fractions distilling below 240°C were removed by low pressure 
distillation. 

The analytical methodology employed to observe the crude oil biode- 
gradation process is shown schematically in the following figure. 

The gas flow was passed through a trap containing CC14, which 
retained the evaporated hydrocarbons, and then through a second 
trap containing a known quantity of 1 N K0H, which retained the 
carbon dioxide. The hydrocarbons were then determined by infrared 
spectrometry. The C02 produced was determined by titrimetry. 

Liquid samples were taken during fermentation. 

The first sample was centrifuged to separate the hydrocarbon phase 
from the aqueous phase, which was then filtered (filter pore diameter 
0.22 jj) to eliminate fine particles in suspension. The following 
were analyzed in this perfectly clarified aqueous phase: 

• total organic carbon (Dohrman DC. 50 instrument), 

• dissolved C02 using the Warburg equipment, 

27 




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28 



• residual phosphorus, 

• residual ammoniacal nitrogen and the intracellular nitrogen concen- 
tration (Kjeldahl's method); these two analyses served to determine 
the quantity of biomass formed. 

The residual hydrocarbons were extracted from a second liquid sample. 
Asphaltenes were precipitated from the hydrocarbon residue using hot 
heptane for one hour, dried and weighed. 

The residue obtained after evaporation of the heptane was processed to 
separate the three main families of hydrocarbons in crude oil: 
saturates, aromatics and resins, by thin layer chromatography (50 mg 
samples) or liquid chromatography (samples weighing about 1 g) . 

The sum of the weights of the three fractions thus recovered, using 
liquid chromatography, compared with the initial rate of the hydrocar- 
bons deposited on the column, always accounted for a proportion 
between 90 and 100 %. 

The loss percentage increased when the test samples were taken at 
increasingly long culture times, hence with samples that underwent the 
longest biodegradation times. These losses are likely to be due 
largely to the retention of polar compounds of the resins on the 
column, compounds that are formed during oxydation reactions, or pos- 
sibly by biochemical co-oxydation, and whose concentration increases 
with biodegradation time. 

Using the different fractions obtained (saturates, aromatics, resins), 
we performed more detailed analyses by gas phase chromatography 
(Varian 3700 chromatograph) equipped with "Splitless" injection and 
flamme ionization detector), a combination of gas phase chromatography 
and mass spectrometry (Varian CH5DF spectrometer), proton NMR that 
yielded the fraction of hydrogen belonging to methyl groups in the sa- 
turates family, 13 C NMR, which yields the percentage of aromatic carbon 
in comparison with total carbon in the aromatic fraction, and by infra- 
red spectrometry on the resins. 



1. BATCH CULTURES 

1.1. Biodegradation of hydrocarbon families and sub-families in ALC 
240 + . 

We selected a mixed culture of bacteria from samples of muds and slud- 
ges collected on places hit by crude oil spills. 

The experiment was conducted with ALC 240 in an initial concentration 
of 2.65 g.l -1 , over a period of 48 hours. 

Of the 2.65 g.l -1 of initial hydrocarbons, 1.08 g.l -1 were consumed, 
representing 41 % degradation. It appears clearly that the saturates 
fraction is most sensitive to biodegradation, because 67 % of this 
fraction were consumed, whereas only 27 % of the aromatics fraction 
were degraded. The quantity of hydrocarbons evaporated was negligible. 

From the standpoint of reproducibility of results, a previous experi- 
ment yielded the following results: hydrocarbons consumed 44 %, satu- 
rates degraded 63.1 %, aromatics disappeared 48.6 %. 

29 



The saturated hydrocarbons were most rapidly biodegraded. 
At the end of the culture, the disappearance of aromatic compounds is 
accompanied by an enrichment of the aqueous phase in organic carbon, 
the concentration of which may reach 250 mg.l - -'-. This observation 
tends to show that a large part of the aromatics are only partly oxi- 
dized before passing into the aqueous phase. 

The resins were only slightly attacked if at all, and the asphaltene 
concentrations at the start and end of the batch culture were absolu- 
tely comparable, demonstrating total insensitivity of these substances 
to biochemical processes. 

The determination of n-alkanes (C14-C35) and detectable isoprenoids 
(C15-C23) by gas phase chromatography showed that these compounds 
disappeared almost totally by the end of the culture. 

The mass spectrometry analysis of the "saturates" fraction showed that 
the alkanes were mainly biodegraded, as 88.9 % disappeared at the end 
of the culture. This enables us to postulate that, in addition to the 
n-alkanes and isoprenoids, which only account for 14.8 % of the 
"saturates" fraction, the bulk of the iso-alkanes present in the crude 
oil was consumed by microorganisms. 

Among the naphtenic compounds, the 1- and 2-cycle naphtenes were mainly 
consumed, with respective biodegradation rates of 44 and 47 %. 

Proton NMR analyses giving the CH3/CH2 ratio, conducted on the satu- 
rates, failed to indicate any significant difference between the start 
and end of the batch culture. 

With respect to the "aromatics" fraction, the action of microorganisms 
mainly affected the mono- and di-aromatic compounds. At the end of the 
culture, all the mono- and di-aromatics with a number of carbons less 
than 16 had disappeared. 

Among the mono-aromatics , the substances most sensitive to microbial 
action were the alkylbenzenes, of which 67.7 % disappeared at the end 
of the culture, and the benzocycloparaf f ins , with a consumption rate 
of 46.2 %. The differences measured for benzodicycloparaf f ins were not 
sufficiently wide to be meaningful. 

As for di-aromatic compounds, the microorganisms displayed a very clear 
effect on the residual concentration of naphtalenes, of which 50 % 
disappeared after 48 hours of culture. 

Through a second experiment, we investigated the changes in composition 
of the aromatics fraction, by drawing a distinction between sulfu- 
compounds and other aromatics. 

Apart from those with a rough formula C n H2 n -10S, the sulfur-containing 
compounds were not attacked by bacteria. The aromatics/sulfur-compounds 
ratio of 0.98 before biodegradation decreased to 0.82 after biodegra- 
dation, showing that it was mainly the non-sulfur-containing aromatics 
(mono- and di-) that disappeared. In addition, the weight percentage of 
sulfur in the aromatics fraction increased with time from 4.05 to 4.15, 
confirming the enrichment of this fraction in sulfur-containing sub- 
tances. 

30 



13 

The C NMR analyses used to quantify the aromatics C/total C ratio 

failed to reveal any significant difference before (43.4 %) an after 
(43.7 %) biodegradation. 

With respect to the resins, part of the polar compounds of this frac- 
tion formed during biodegradation remained absorbed on the liquid chro- 
matography column, and consequently the analyses performed on the eluted 
resin fraction were not truly representative. This retention of polar 
compounds of the liquid chromatography column was confirmed by elemental 
analysis, showing oxygen to drop from 2.75 % (by weight) at the start 
of the batch culture to 2.35 % at the end of the culture. 

The determination of molecular weights of the resins yielded the 
following results: 690 at the start of the batch culture, 740 at the 
end of the batch, namely very slightly differing molecular weights. 



1.2. Examination of oxidation products. 

Analyzing the aqueous phase sampled at the end of the batch culture 
(volume sampled = 1 liter), centrifuged and filtered, we found a total 
organic carbon concentration of 260 mg.1-1. 

We carried out an esterif ication (BF3-CHgOH) of the compounds of this 
aqueous phase. The organic extract was evaporated and weighed. The 
weight of the extracted compounds, related to one liter of culture, 
was 120.2 mg. In the acidified residual aqueous phase, initial extrac- 
tion with CHpClp, followed by a second extraction with benzene, yielded 
a new organic phase that contained polar compounds such as alcohols, 
ketones and phenols, which represented 7.58 mg/1 of aqueous phase after 
evaporation. 

Identification by GC/MS coupling of compounds separated by gas phase 
chromatography was difficult because of the presence of a strong 
background of poorly resolved constituents, which could be hydrocarbons. 
Despite these problems, we succeeded in identifying normal and iso 
acidic compounds in the aqueous phase, in the form of their correspon- 
ding esters, obtained after esterif ication of the aqueous phase. 

The GC/MS coupling enabled us to observe the masses m/e = 74 characte- 
ristic of n-esters, and m/e = 88 characteristics of iso-esters. 



1.3. Changes in microbial flora with time. 

Three samples were taken during the batch culture, the first at the 
start of growth, the second during the active biodegradation phase 
(after 15 hours of culture), corresponding to consumption of the satu- 
rated hydrocarbons, and the third after 25 hours, in the slowdown 
period of the biodegradation process, corresponding to microbial 
attack of the aromatics. 

In the three different stages investigated, different dominant strains 
were found, belonging to two genera only, Pseudomonas and Moraxella , 
confirming that changes in the crude oil during a biodegradation pro- 
cess are accompanied automatically by changes in the microbial flora. 
At the start and middle of the batch culture, we chiefly identified 

31 



bacteria of the genus Moraxella, indicating that these strains are per- 
fectly adapted to the hydrocarbons present at that particular time in 
the culture and, being dominant, they therefore naturally and preferen- 
tially consumed the hydrocarbons of the "saturates" fraction, as these 
types of constituents were biodegraded during this period. At the end of 
the culture, however, when the "aromatics" fraction was attacked by the 
microorganisms, only the Pseudomonas strains were dominant. 

This investigation again confirms that, to observe a significant 
degradation of hydrocarbons in a crude oil containing a wide variety 
of compounds, a mixed culture of bacteria is certainly more effective 
than a pure bacteria, of which the metabolism is only adapted to a 
given type of constituent. 



1.4. Toxicity analysis of oxidation products. 

During the different ALC 240 + crude oil biodegradation experiments, we 
always observed a substantial rise in total organic carbon (TOC) 
concentration in the aqueous phase with the passage of time, with a 
regular final concentration around 200 mg.l . 

We decided to evaluate the potential toxicity of these solubilized 
products in the aqueous phase, enriched mainly in aromatics and oxi- 
dation products of certain hydrocarbons present in the crude oil. 

In particular, the mutagenicity of two samples was determined by the 
Ames test, the procedure of which is described in detail in Mutation 
Research 1975, 31, pp. 347-364. The first sample was taken at the 
start of the culture (with a TOC of 30 mg.l - - 1 -), and the second at the 
end of the batch culture (sample with a TOC of 210 mg.l -1 ). 

The correlation between carcinogenic properties and mutagenic properties 
of 300 compounds was pointed out in Proc . Natl. Acad. Sci., (USA), 
1975, 72, pp. 5135-5139. 

The principle of the Ames test is to measure the mutagenic properties 
of compounds that may be carcinogenic in Salmonella bacteria. 

The two samples were tested in a range from 0.1 to 500 jul on three of 
the five strains used in the Ames test (TA.1538, TA.98 and TA.100) in 
order to detect the mutagenicity of products such as HAP, for example. 

No mutagenic activity was detected in these two samples. 

It was shown finally that neither of these two samples had any toxic 
effect on the three strains tested (TA.1538, TA.98 and TA.100). 



1.5. Study of the biodegradation of a mixture of pure hydrocarbons. 

The mixture of pure hydrocarbons consisted of two n-alkanes, hexadecane 
and octacosane, one isoprenoid, pristane, a two-ring naphtene, decaline, 
two mono-aromatics , p-cymene and dodecylbenzene, one di-aromatic, 
dimethyl-naphtalene , one tri-aromatic , phenanthrene, and two sulfur- 
containing aromatics, benzothiophene and dibenzothiophene. 

32 



Experiments were conducted in batch culture in the same conditions as 
those described for Arabian Light Crude. The mixed culture of bacteria 
used was the mixture of the strains Pseudomonas and Moraxella isolated 
and purified, described in Section 1.3. By sucessive cultures in flasks 
with the pure hydrocarbon mixture as the only carbon substrate, the 
mixed culture was progressively adapted to grow on these ten hydrocar- 
bon compounds. 

The culture was carried out in batch for 61 V z hours, and we observed 
the changes in the biomass, total hydrocarbons, and each compound, and 
also the organic substances that passed into the aqueous phase. 

Following a lag phase of about 10 hours, a growth acceleration phase 
was observed up to the 25th hour, then a linear phase from the 25th to 
the 35th hour, and finally the slowdown of bacterial growth. At the end 
of the batch, the dry cell weight was 0.5 g.l -1 . The biodegradation 
process of total hydrocarbons perfectly matched the microorganism growth 
pattern. After 61 Y 2 hours, 82.8 % of the hydrocarbons were degraded. 

It appears that the three most volatile compounds, paracymene , decaline 
and benzothiophene, could not be found after extraction, from the very 
outset of the experiment. These three products must therefore disappear 
chiefly during extract evaporation operations. However, a small propor- 
tion passes very rapidly into the aqueous phase in the marine environ- 
ment, because the latter contained oxidation products of p-cymene among 
others, as well as benzothiophene. 

The two n-alkanes, n-hexadecane and octacosane, and the dodecylbenzene 
were consumed first. For these three products, which practically 
disappeared by the end of the batch, their respective biodegradation 
rates after 37 Y 2 hours only of culture were 93 %, 87.5 % and 80 %. 
Pristane only started being attacked after 24 V z hours, and was 69.2 % 
consumed at the end of the culture. During the last 20 hours, while 
practically no alkanes or alkylbenzene remained in the reactor, dimethyl- 
naphtalene was biodegraded (disappearance rate 67 %) . Phenanthrene and 
dibenzothiophene were consumed very little if at all. 

These results perfectly confirm those found with Arabian Light Crude, 
which showed that alkanes and isoprenoids were attacked first, follo- 
wed by mono- and di-aromatics. Similarly, it was observed that tri- 
aromatics and sulfur-containing aromatics were only slightly sensitive 
or insensitive to the action of microorganisms. The fact that dodecyl- 
benzene disappeared fairly rapidly is explained by the presence of the 
linear chain which, like the n-alkanes, is readily accessible to 
bacteria. 

The total organic carbon concentration (TOC) measured in the medium was 
385 mg.l -1 . After esterif ication and evaporation of the organic extract, 
esters and some other polar compounds were found in a concentration of 
221.5 mg.l -1 . 

We carried out analyses by gas phase chromatography and GC/MS coupling 
in an attempt to identify these products. 

Since many products were present in trace amounts, and several of them 
were eluted simultaneously and combined in a single peak, we encountered 
considerable difficulty in identifying them on the mass spectrometer. 

33 



2. CONTINUOUS CULTURES 



In continuous culture, since this technique serves to check the concen- 
trations of all the nutritive elements at all times, and to adjust these 
concentrations to limit thresholds, thus closely approaching conditions 
encountered at sea, we attempted to quantify the nitrogen, phosphorus 
and oxygen requirements for the biodegradation of given quantities of 
hydrocarbons present in ALC 240+ . 

The following operating conditions were used: 

• Dilution rate D = 0.04 h~ 

• Temperature 20°C 

• Reactor volume 2 liters 

• Agitation 520 rpm 

• Ph of culture 8.1 

• GHSV 1 

(except for quantification of the oxygen requirements, where the GHSV 
was varied from 1 to 0.25). 

• ALC 240 concentration 
entering reactor 

always about 2.5 g.l - 

For a given concentration of an element (nitrogen, phosphorus or oxy- 
gen) entering the reactor, the experimental time was about one week. 
Upon each alteration in operating conditions, it was necessary to wait 
another week for equilibrium to be re-established. 

When the residual concentration of nitrogen was in excess, the bacterial 
consumption of this element per mg of hydrocarbons degraded ranged from 
0.1 to 0.11 mg. However, when the nitrogen reached a limit with residual 
contents around 1 mg/liter, the nitrogen requirements dropped to 0.07 mg. 

The same occurence was observed with phosphorus. In conditions of non- 
limitation, the biochemical consumption of phosphorus, around 0.012 to 
0.013 mg/mg of hydrocarbons consumed, declined to only 0.005 mg/mg of 
hydrocarbons consumed when the residual concentration of elemental P 
reached a limit ( C 1 mg.l - -'-). 

With respect to oxygen, microorganism requirements fluctuated between 
1.4 and 1.9 mg oxygen per mg of biodegraded hydrocarbons, for residual 
dissolved oxygen concentrations between 50 and 7 % of the saturation 
value. 



34 



THE AMOCO CADIZ ANALYTICAL CHEMISTRY 
PROGRAM 

by 

Paul D. Boehm, Ph.D. 

Environmental Sciences Divisions, ERCO (Energy Resources Company, Inc.), 
185 Alewife Brook Parkway, Cambridge, Massachusetts 02138 



TABLE OF CONTENTS 

1 . INTRODUCTION 

2. METHODS AND MATERIALS 

2.1 Sediments and Sediment Cores (Extraction and Processing) 

2.2 Plant and Animal Tissue 

3. RESULTS AND DISCUSSION 

3.1 Overall Findings 

3.1.1 Weathering of AMOCO CADIZ Oil 

3.1.2 Persistence of Marker Compounds 

3.1.3 Residues in Tissues 

3.1.4 Environmental Variability 

3.2 Surface Sediments (Atlas, University of Louisville) 

3.3 Offshore Sediments (Marchand, CNEXO) 

L'Aber Benoit Sediments (Courtot , U. West Brittany) 

3.4 Sediment Cores (Ward, Montana State University) 

3.5 Oysters and Plaice (Neff, Battelle) 

3.6 Oysters and Fish (Michel, ISTPM) 

3.7 Seaweed and Sediments (Topinka, Bigelow Laboratory 
for Ocean Sciences) 

4. Conclusions 

5. REFERENCES 



35 



INTRODUCTION 

All fate and effects studies of oil spills in the marine environ- 
ment depend on analytical chemical information concerning the distribu- 
tion and composition of the spilled oil. This includes petroleum 
hydrocarbon concentrations and compositions in water, sediment, and 
tissue samples. In turn, this information can be used to deduce the 
nature of the weathering process (including evaporation, dissolution, 
and biodegradation) , biological assimilation and depuration, and the 
mass budget of the oil. Thus the analytical chemistry component of the 
AMOCO CADIZ research program provides crucial information to many 
other components of the program in the investigation of the time- 
dependent fate and effects of this spill. 

During the six weeks following the grounding of the supertanker 
AMOCO CADIZ on March 16, 1978, oil came ashore along 320 kilometers of 
the Brittany coastline (Gundlach and Hayes, 1978). Various shoreline 
types were impacted (e.g., rocky shores, sand flats, coastal embay- 
ments, tidal mud flats and salt marshes). During the early stages of 
the spill, oil was transported offshore and deposited in the benthic 
environment. The fate of petroleum residues deposited in these impact- 
ed areas was and continues to be affected by coastal processes which 
dictate such factors as wave energy and sediment transport, and create 
environments of differing substrate character (e.g., grain size), 
chemical status (oxidizing versus reducing) , and biological activity 
(e.g., microbiological biomass) . All of these factors and others 
(e.g., light intensity) combine to determine the weathering character- 
istics of the residual petroleum assemblage. 

Biological populations initially impacted by the spilled oil may 
be subject to chronic exposure to petroleum hydrocarbons associated 
with (and released from) the substrate to which they are closely 
linked, or they may undergo rapid or slow depuration of initial resi- 
dues if no longer exposed to oil, via transplantation or due to flush- 
ing by "clean" seawater. Such differential exposure histories have 
been previously observed to profoundly affect the spilled oil residual 
body burdens in marine organisms (Boehm et al., 1982). 

Although oil spills have received increasing attention from the 
scientific community during the past decade, there have been few 
opportunities to examine the chemical compositional changes in beached 
or sedimented oil in a variety of coastal environments, over a signifi- 
cant period of time and to examine uptake (impact) and depuration 
(recovery) of petroleum by marine organisms. A detailed examination of 
the chemical changes in oiled substrate suggests both the anticipated 
residence time of deposited oil, and the potential for biological 
damage of the petroleum residues. Rashid (1974) examined compositional 
changes of Bunker C oil from the ARROW spill in Nova Scotia at dif- 
ferent coastal locations. Other than this study only site-specific 
studies of the geochemistry of petroleum weathering (e.g., Mayo et al., 
1978; Blumer et al., 1973; Teal et al . , 1978) have been undertaken. 



36 



Uptake and depuration by organisms have been the subjects of many 
laboratory experiments (e.g. Neff et al., 1976; Roesijadi et al., 1978) 
but relatively few real spill scenarios (e.g. Boehm et al., 1982; 
Grahl-Nielsen et al., 1978). 

This report is intended to present an overview of the chemistry 
program along with enough supporting data and interpretations for each 
program element to make this a self contained document. After a 
methods section, a summary of the general findings is presented. 
Discussions of the analytical chemical and biogeochemical findings of 
each of the six specific investigations follow; the last section draws 
conclusions from the study as a whole. Much of the raw analytical data 
has been omitted here for brevity. Tabulations of analytical data are 
available either from the individual principal investigators or 
from the chemistry group. This data has formed the basis of several 
publications to date (Calder and Boehm, 1981, Boehm et al., 1981, Atlas 
et al., 1981, Winfrey et al. 1981) as well as several manuscripts in 
preparation. Additional interpretative details are found in these 
manuscripts. 

METHODS AND MATERIALS 

As part of the NOAA/CNEXO research program to examine the long- 
term fates and effects of the spill, we obtained samples of frozen 
intertidal surface sediment, benthic sediment, sediment cores, oysters, 
flatfish and macroalgae from a number of U.S. and French investigators 
(Table 1) . 



TABLE 1. Summary of AMOCO CADIZ chemistry program. 



1 - Chemical Composition, Weathering, and Concentrations in 

Surface Intertidal Sediments (Atlas; Calder): 1978-1981 

2 - Chemical Composition, Weathering, and Concentrations in 

Subtidal Sediment (Marchand, Courtot) : 1978-1979 

3 - Chemical Composition, Weathering, and Concentrations in 
v Intertidal Cores (Ward): 1978-1980 

4 - Chemical Concentrations and Composition of Oil in Oysters 

and Flatfish from Abers (Neff) : 1978-1980 

5 - Chemical Concentrations and Composition of Oil in Variety of 

Fish and Oyster Tissues (Michel): 1978-1979 

6 - Chemical Concentrations and Composition of Oil Associated 

with Seaweeds (Topinka) : 1978-1980 



37 



2.1 Sediments and Sediment Cores (Extraction and Processing) 

Samples of surface sediment or specific depth interval sections of 
sediment cores were solvent-extracted and fractionated according to an 
ambient temperature solvent drying and solvent extraction procedure 
based on that of Brown et al. (1980) as revised by Atlas et al. (1981) 
and Boehm et al. (1981). The procedure, involving methanol drying and 
ambient temperature extraction with a methylene chloride/methanol 
azeotrope, is illustrated in Figure 2.1. The concentrated extract is 
displaced with hexane and charged to a glass absorption chromatography 
column (1 cm i.d.) containing 10 g fully activated (150°C) 80-100 mesh 
silica gel topped with 1 g 5% deactivated alumina and 1 g activated 
(i.e. acid washed) copper powder. The column, which is wet packed in 
methylene chloride, is rinsed with this solvent followed by hexane. A 
0.5 ml volume of extract is charged to the column and eluted with 
hexane (17 ml, f]_) » hexane: methylene chloride (21 ml, f 2) , and 
methanol (20 ml, f 3) . The fractions are collected separately, reduced 
in volume, desulfurized using an activated (1 N HC1) copper powder 
slurry, and an aliquot weighed on a Cahn electrobalance. The f^ and 
f2 fractions are then analyzed by fused silica capillary gas chroma- 
tography (FSCGC flame ionization detector) and a selected set further 
scrutinized by gas chromatographic mass spectrometry. FSCGC analysis 
determined the overall composition of the sample by appraisal of the 
distribution of resolved (peaks) and unresolved (hump) features, 
as well as the specific quantities of individual n-alkane (C^g to C32) 
and isoprenoid (C15 to C20) compounds. GC/MS/computer analyses focused 
on the list of saturated and aromatic compounds presented in Table 2 to 
confirm the identities of compounds or to quantify minor, but important 
"marker" compounds. 

Details of the GC and GC/MS analytical procedures are presented in 
Table 3. 

Quantification of GC traces was according to the internal standard 
method wherein quantities of individual hydrocarbons are computed. 
Several other GC-derived parameters were routinely calculated on sample 
data. One of these was the n-alkane to isoprenoid ratio (ALK/ISO) in 
the C13 - C19 range: 

ArK/Tsn = n ~ C 14 + "-Cis + n-Ci e. + n C, 7 + n-Ci a 

' 1380 + 1450 + 1650 + 1710 + 1812 a 



a GC retention indices of isoprenoids: 1450 = farnesane, 1710 = 
pristane, 1812 = phytane. 

This ratio, beginning at ^7 in the reference oil is quickly 
decreased due to preferential bacterial degradation of n-alkanes 
versus the branched isoprenoids. 

The carbon preference index (CPI) , the ratio of odd chain alkanes 
to even chain alkanes in the n-C26 to n-c 31 range, is defined as 
follows: 

2(n-C ?7 + n-Coq) 

CPI = n-C 26 '+ 2n-C 2 Q + n-C 30 

38 



3«dim«nt 



Ducard 



Stdimtnt 5*fci« 



Vlatnanoi Wijn 



Cn«d Sadiment 



Methanol 



1 1 1 SOq in Teflon ;ar or ctntrifuge :uoa 
2) Internal stjnaaraj 
3)CH30H,CH2C2 11:9) 

'41 rlutfl WfN^ 

«SI Shake it amoient -.emotrature 40 hours .vitri 
aoivent cnanoa after 16 ana 24 iourj 



CH3OH/CH2C2 
ixtractl 



(1) NaC! saturated) 

(2) Aodifv v»<Hcl 

3) sxtract 3x «/CH2^ : 2 



Methylene 
Oionde 
CH2C2 1 



Aqueous 

Metnanai 



ill Camome 

2) Orv over Ma2S04 

3) Concentrate to 100 -u 
41 iVeion 



2 scare 



Concentrated 
extract 



Htxana ifii 
Weigh Aliduoti 



| 1 ) Oupiact «itn Hexane 

Alumina/ 
Silica Gd 
Column 
Chromatograony 



-lexane/ Methylene 
Chloride f 21 

Weigh Aliquot) 



Methanol /31 
Weign Aliouotl 



Saturated 
rtyoroearoons 



I 



GC 2 
GC 2 MS 



Aromatic 
Hydrocaroom 



GC 2 
GC 2 MS 



foiar MSG 
Comooundi 



i 



Store 



FIGURE 2.1. Analytical scheme for sediment samples. 



39 



TABLE 2. Focus of GC/MS analyses. 



Saturated hydrocarbons 

Pentacyclic triterpanes (hopanes) 

Aromatic hydrocarbons 

Alkylated benzenes (C 4 , C 5 , Cg) 

Naphthalene and alkylated naphthalenes (C lf C 2 , C3, C4) 

Fluorene and alkylated fluorenes (C lf C 2 / C3) 

Phenanthrenes and alkylated phenanthrenes (C^, Co/ C3, C4) 

Fluoranthene 

Pyrene 

Benzanthracene 

Chrysene 

Benzo fluor an thenes 

Benzo (a) pyrene 

Benzo (e) pyrene 

Perylene 

Aromatic heterocyclics 

Dibenzothiophene and alkyl dibenzothiophenes (C^, C 2 » C3) 



TABLE 3. GC and GC/MS conditions. 



GC 



GC/MS/COMPUTER 



Instrument 


HP 5840A 


Column 


SE-30 (saturates) 


1. 


Liquid 
phase 


SE-52 (aromatics) 


2. 


Type 


Fused silica 

(J&tf Scientific) 


3. 


Diameter 


0.25 id 


4. 


Length 


30 m 


5. 


Carrier 


Helium 8 1 ml/min 


Temperatures 
1. Oven 


40-290 3 3'/min 


2. 


Injector 


250* C 


3. 


Detector 


300* C (FID) 


Ionization 
vo 1 1 ag e 


- 


Electron 
multiplier 
vo 1 1 ag e 


- 



HP 598 5 
SE-52 



Fused silica 

(JiW Scientific) 
0.25 id 
30 m 
Helium 9 1 ml/min 

40-290 @ 3*/min 

250* C 

300 (ion source) 

70ev 

2200 volts 



Scan conditions 



40-500 amu 3 225 amu/sec 
(1 scan/2 seconds 
minimum of 5 spectra 
per peak) 



40 



The CPI ranges from values of 1, where oil is present, to values 
greater than 1 if odd chain biogenic terrigenous n-alkanes dominate the 
higher boiling n-alkanes. 

Quantification of aromatic hydrocarbons was accomplished using the 
technique of mass fragmentography wherein the computer stored raw GC/MS 
data is searched for parent ions (m+) and the total ion currents for 
these ions is integrated and tabulated. Retention times of the parent 
ion mass fragmentograms obtained were compared with authentic standards. 
The total ion current for each parent ion is compared with that for the 
internal standard (deuterated anthracene) and instrumental response 
factors applied. Where authentic polynuclear aromatic hydrocarbon 
(PAH) standards were not available for relative response factor 
determination, a response factor was assigned by extrapolation. 

All of the above techniques were applied successfully to the 
analyses of replicates of a NOAA intercalibration sediment sample, 
Duwamish I, prior to commencement of the program and to Duwamish II 
during the program. Additionally, the EPA "megamussel" intercalibra- 
tion sample was successfully analyzed for PAH levels. 



2.2 Plant and Animal Tissues 

All specimens of wet tissue, freeze dried tissue, and plant 
material were thawed and homogenized, or in the case of the seaweed 
tissue were cut into small pieces, prior to placement in a digestion 
flask. The samples were added to 250 ml Teflon screw top jars. The 
digestion, extraction, and fractionation schemes were similar to those 
developed by Warner (1976) except that the digestion was performed 
using a 0.5 N KOH/distilled water/distilled methanol system heated in a 
boiling water bath for 4 hours to achieve complete digestion and hence 
release of hydrocarbons from the cellular matrix (Boehm et al . , 1982). 
Internal standards were added prior to digestion and carried through 
the entire procedure (Fig. 2.2) (f^ = androstane; f2 = deuterated 
anthracene or phenanthrene) . 

The digestate was extracted three times with distilled hexane in 
the jar, the mixture being centrifuged between extractions. The 
extracts were combined, concentrated to 0.5 ml, weighed on a Cahn 
electrobalance, and fractionated on an alumina over silica gel column 
(see previous section) . Two fractions corresponding to the saturated 
or fi (hexane eluate) and the aromatic/olef inic or f2 (hexane:methyl- 
ene chloride eluate) hydrocarbons were obtained for gas chromatographic 
and combined gas chromatographic/mass spectrometr ic analyses (GC/MS). 



41 



T.ssue Semoie 
S50 grams Wet) 



HI Dissect = iesh 

12) Homogenize 

!3) Aod to Teflon Jar 

141 Add Internal Hvoroc»rOon Stanaaros 

(5) 4N KOH laql 

(6) Fiujn Jar witn N^ 
i7l Saai 

18/ Digest (Saponify* Overmgn: at Room Tsmoereture 





Digtrtan 






1 1 1 Transfer tc 
(2) Add Satur 
!3) Extract 2 ' 


Seoaratorv Punne' 
red NaC 
"imes witn Hexane 




Comoinad Hexane extracts 






(1) Concentrate 

(2) Dry Over Na 2 S04 




Concentrated Extract 








(11 Alumina Cleanuo 

(2) Metnyiene Chionde Slution 

(3) Duoiace witn Hexane 
Alumina/ 

Silica Gei 

Column 

Chromatograony 


Hexane ( f i ) 
(Weigh) 

r 




Hexane/MeClolf) 

(Weigh) 

(1 1 Resaponify 

or 
(2) Gei Permeation 

HPLC Cleanuo 
r ^ 



Metnanol ( f 3 ) 
(Weign) 



Saturated 
Hydrocarbons 



(1) Aromatic HydrocarDons 

(2) PCS 



Poiar NSO 
Comoounas 



i 

GC2 



1 



GC2 

GC^/MS 



i 

Store 



Fiaure 2.2. Analytical scheme for tissue samples (after Warner, 1976; Boehm et al., 1982). 



42 



3. RESULTS AND DISCUSSION 

3.1 Overall Findings 

Several general trends in the data presented in the following 
sections should be noted here along with several considerations of the 
use of marker compounds as "fingerprints" to trace aged AMOCO CADIZ oil 
in environmental samples. 

3.1.1 Weathering of AMOCO CADIZ Oil 

The chemical composition of spilled oil from the tanker changed 
markedly over the first days to weeks, both at sea and once associated 
with sediment (Atlas et al., 1981; Calder and Boehm, 1981; Boehm et 
al., 1981). The changes are well documented in Figures 3.1 and 3.2 and 
are summarized in Table 3A. For comparison, the background saturated 
and aromatic hydrocarbon composition of sediment samples is illustrated. 
The non-impacted sediments contain: 1) an unresolved complex mixture 
(UCM) of hydrocarbon material in both fractions, 2) terrigenous n- 
alkanes (odd chain) in the saturated fraction, and 3) pyrogenic PAH 
compounds in the aromatic fraction. Weathered AMOCO CADIZ oil is 
identified as such in the sections that follow based on the following: 

1) The presence of large UCM in f^ and f 2 fractions with residual 
triterpenoid peaks. 

2) The presence of isolated isoprenoid hydrocarbon compounds in 
the resolved (peak) part of the GC trace (in samples during 
the first year post-spill only) . 

3) The dominance of alkylated phenanthrene (C 2 , C3, C4) , di- 
benzothiophene, naphthalene, and fluorene (in earlier samples) 
compounds in the aromatic fraction and a dominance of these 
aromatics versus pyrogenic PAH (i.e. fluoranthene, pyrene, 
benzanthracene, chrysene, benzopyrenes, etc.). 

3.1.2 Persistence of Marker Compounds 

The most persistent compounds in the saturated (f^) fraction are 
the pentacyclic triterpanes (PCT) ; in the aromatic (f2) fraction the 
alkylated phenanthr enes (P) and dibenzothiophenes (DBT) are most 
persistent. To examine the PCT compound distribution, GC/MS analysis 
of the f^ fraction was necessary (e.g. Figs. 3.3 and 3.4). This 
results in a "terpanogram" yielding information on the relative concen- 
tration of eight PCT compounds used by several investigators as indica- 
tors of presence and origin of petroleum (e.g. Dastillung and Albrecht 
1976; Pym et al., 1975) . 

Two PCT time series (Fig. 3.5) reveal that the PCT fingerprint is 
rather constant throughout the December 1978 to March 1980 time period 



43 



ae = E3£\CE '.tC'-SSE S* -•* 







3 STAGE I -i6A~^6fliNC S*tu'jito -.arotveo^ti 



i ■- i ■- : 



^ 



nfljp^^ 



C STAGE I *EATh£«inG iSjtwiita M,ar<jcjrExy-t, 



i * H 



1 



iiiiPi 



Uj 



S T AGE 3 «*TK6i»iNG S*(-'»i«o "•vdrt»c*t»«i 







E STAGE * «Eath6ring S.tu'»im " 






P 



> jXU>*'^ > 



Ai 



t 9*.C*G»*Gi.NC 'S*t^'»<« H »0"*«*'W« P 



1 



llllfc 



Wj 



FIGURE 3.1. Weathering patterns of saturated hydrocarbons in AMOCO CADIZ 
oil. 



44 



A REFERENCE MOUSSE lAromji.cii 

, * * 




W«* J w»' , '- tW ''*"* 



STAGE 1 WEATHERING iAfomanci) Alkti 
: DBT 



J" 



• 



^Ji'VWWvv 



H, 



C STAGE 2 FEATHERING .Aromit.cn 



^ 



>**** 



V 



y 



STAGE 3 FEATHERING lAiomarcil 



..>' 



^ 



WP 



/ 



jijilW/rtw'W 



/ 



C PYPOLYTlC PAH SOURCE lAfOPULCi 



1 



lilt 



piW,,i; 



PV-P Y '«n« 
3A«8tnz»ntn'in«na 

CHV-Chry«ft 

aF-Benio'iucant^'ef 1 * 
SEP 9AP"8enioove f, «i 

3Ber'"6enioo«'v>en« 



FIGURE 3.2. Weathering patterns of aromatic hydrocarbons in AMOCO CADIZ 
oil . 



45 



TABLE 3A. Weathering of AMOCO CADIZ oil. 



RAPID 

1. Loss of volatile (<n-C^5) hydrocarbons due to evapora- 
tion of: 

a. alkanes 

b. aromatics - benzenes, naphthalenes, biphenyl (one- to 
two-ring aromatics) 

2. Relative and/or absolute increase in unresolved complex 
mixture. 

MODERATE 

1. Microbial degradation of n-alkanes; preferential attack of 
n-alkanes versus branched alkanes (i.e., decrease in ratio 
of alkanes to isoprenoids) . 

2. Loss (to solution or other processes) of most resolved 
saturated hydrocarbon GC traces. 

3. Emergence of triterpanes as major molecular markers in 
saturated fraction. 

4. Increase in UCM, with formation of secondary (bimodal) UCM 
distribution. 

5. Loss of fluorenes (two aromatic rings, one saturated ring) 
and alkyl naphthalenes. 

6. Increase in abundance of polar fraction. 
LONG 

1. Persistence of alkylated phenanthrenes and alkylated 
dibenzothiophenes. 

2. Increase in polar fraction. 

3. Loss of long chain n-alkanes and isoprenoids. 



46 



■»e e EAS%c= uocsse 



">'^04M -* 



rtrfr^^-rrVrV^^ 1 ^ 



1 



h 



WJCJ 



,^^VVV<W*^ 



<v< 



ivUA 



A 



A 



uSV-sA^. 



^*AmA*J— .L-.L 



JjLo_,_ 



_ 






FIGURE 3.3. GC/MS selected ion searches for pentacyclic triterpanes (ho- 
panes) in AMOCO CADIZ reference and November 1978 weathered 
oil in sediments. 



191 .0 




— i 1 1 1 1 1 1 1 r~ 

64 fig 6S fi7 6H 69 70 ZJ 2£_ 



1 1 1 1 1 1 1 1 1 

rn 71 7 5 7R Z7._7fl _ jza _aa_ .ooJ 



FIGURE 3.4. Triterpane (m/e 191) mass chromatogram of weathered oil. 
1,2 = Trisnorhopane (Czi^^e) , 3 = Norhopane (C29H50), 4 = 
Hopane (C30H52), 5,6 = Homohopanes (C31H51J, 7,8 = Bishomo- 
hopanes (C23H56). 



47 



fli-Liftim Mi.u".- 



i !•- r-. ii);n 



l..lv 10/0 



M.IM I. I'tllll 



I 7 1 1 5 6 / n 



i?3isc;n i ? 3 4 5 G / n 

STATION 3 ILE GRAND MARSH 



I/ill 



ndpi^ncp Mnutsr 



I). - i-i.il*. 19/B 



Jul, 1979 



1 7 3 4 5 B 7 



123450/8 17 3-10 7 B 17345618 

stationc Alien wnAcii 



FIGURE 3.5. 191 terpanograms. (1,2 = Trisnorhopanes , 3 = Norhopane , 4 
Hopane, 5,6 = Homohopane s , 7,8 = Bishomohopanes) 

at the two stations. Note that the PCT fingerprints of AMOCO CADIZ and 
TANIO oils are quite distinct (Fig. 3.6), notably in the ratios of 
compounds 1, 2 and 5, 6. Thus it appears that PCT fingerprints offer a 
good means to trace AMOCO oil in highly weathered samples when most 
other identifiable molecular characteristics have been lost. 



I 2 3 4 5 6 1 8 



AMOCO CAOI/ 



17 3 4 



IANIO SIAI ION I I 



FIGURE 3.6. 191 terpanograms of crude oils. 

48 



As the most persistent aromatic compounds, the P and DBT compounds 
(mainly C 2 , C 3 , and C 4 ) mark AMOCO CADIZ oil in tissue (oysters) and 
sediments through mid-1980. The final (June 1981) sediment sampling 
failed to reveal significant P and DBT levels in any of the stations. 
The latest (1981) status of the oyster P and DBT levels is unknown. 
However, through most of the data to be discussed, the P and DBT 
compounds dominate the f 2 distribution. The ratios of C 2 P/C 2 DBT and 
C3P/C3DBT, used by Overton et al. (1981) to differentiate oils, in this 
spill remain in the 0.3-0.6 range. The use of this ratio is discussed 
in the text. 

3.1.3 Residues in Tissues 

As stated, the P and DBT compounds are most readily associated 
with oyster tissue samples in the two-year period following the spil- 
lage. The branched alkanes (isoprenoids) also persist throughout this 
period. 

3.1.4 Environmental Variability 

A major question in oil spill studies and for that matter environ- 
mental studies in general is the question of patchiness of pollutant 
distributions and the variability due to patchiness in chemical meas- 
urements. To shed some light on this subject two sets of measurements 
are available. Two principal investigators (Atlas and Ward) obtained 
samples at the same time and location in several instances, Atlas 
sampling the top 3-5 cm, Ward sampling an entire sediment core but 
subdividing the top 0-5 cm section. The total hydrocarbon values 
(Table 4) reveal wide disparities where contamination is very heavy 
(pooling of oil in the lie Grande) but reasonable to excellent agree- 
ment in most cases. (Note also that additional replicate analyses are 
available for sediment samples in Section 3.2 as well). 



TABLE 4. Analysis of sampling variability. 



TOTAL HYDROCARBONS (f L + f 2 ) (ug/g) 



STATION 


DATE 


ATLAS (SURFA( 


lie Grande 


12-78 


650/1300 a 




3-79 


4,700 


L'Aber Wrac'h 


12-78 


400/400 a 




3-79 


870 




7/8-79 


390 




11-79 


1,100 



WARD (0-5 cm) 



1,100 
700 

770 
1,100 

290 
1,100 



a Replicate samples. 



49 



3.2 Surface Sediments (Atlas, University of Louisville) 

The frequency of sampling for surface sediment (0-3 cm) is shown 
in Table 5. Ten primary locations were sampled repeatedly (Fig. 3.7). 
Results of total hydrocarbon determinations for the ten stations, as 
these concentrations varied with time, are presented in Figures 3.8 
through 3.12. Also included in these figures are source evaluations 
for each sample hydrocarbon assemblage, based on GC information. The 
biogenic (B) category indicates that terrigenous odd chain n-alkanes 
dominate the f^ GC trace. The pyrogenic (P) category signifies an 
important abundance of combustion-related polynuclear aromatic hydro- 
carbons (PAH) in the f2 fraction as well as the presence of some 
unresolved material (UCM) in both the f^ and f2» In those samples 
labeled B or B/P the primary sources of hydrocarbons are as indicated 
although a small fraction of the hydrocarbons may consist of petroleum. 
Figure 3.13 summarizes these source criteria. Only GC/MS analysis of 
each sample would definitely eliminate the small chance of a false 
negative (i.e. not finding AMOCO oil where there were traces). 

The error bars in the figures indicate that two determinations 
were made for the December 1978 samples (Table 6) . All other determin- 
ations were based on one replicate. Note that the coefficient of 
variation ranges from .01 (1%) to .94 (94%). The higher variability is 
observed in samples with the lowest and highest (^1000 ppm) absolute 
concentration levels, the former due to natural patchiness, the latter 
owing to "pooling" of oil in heavily impacted stations. 

GC/MS results are available for stations 3, 5 and 7 throughout the 
study period and are presented graphically in Figures 3.14 through 
3.33. These semi-log plots illustrate quantitatively the aromatic 
composition of all samples normalized to C3 dibenzothiophene or where 
C3DBT is absent to pyrene. C3DBT was used to normalize the data as it 
is assumed that these compounds are the slowest to weather of all of 
the aromatic hydrocarbons. 

All AMOCO CADIZ-impacted stations illustrate a normal weathering 
sequence (i.e. see Fig. 3.1). However, fresh inputs of petroleum were 
observed to impact the region of stations 7 and 8 in the form of tar 
chips during November 1979 and stations 2, 11 and 12 in the form of oil 
from the TANIO spill in August of 1980 (Fig. 3.34). 

Although a wide range of residual oil concentrations appear in the 
various samples, several trends in the data seem apparent. Stations 1, 
9, and 10 remain unimpacted by the spill throughout the study. Station 
2 remains unimpacted until a secondary petroleum input influences its 
hydrocarbon chemistry in November of 1979 (the timing of the secondary 
tar impact at stations 7 and 8 also is probably related to leakage from 
the sunken tanker) and again in August of 1980, the latter relating to 
the TANIO spill, also readily detected at Stations 11 and 12 at this 
time. Through March of 1980 weathered AMOCO CADIZ oil is readily 
detected at Stations 3, 4, 5, 6, 7 and 8. However, the results of the 
August 1980 samplings indicate that inputs of non-AMOCO CADIZ hydro- 
carbons (i.e. background) at Stations 6 and 8 become dominant. At 
stations 3 and 7 where GC/MS data exists, the main AMOCO CADIZ aromatic 

50 





.., ^ 




:>( MM III I l ri mil Vt 






FIGURE 3.7. Surface sediment ' sampling locations (Atlas) 



TABLE 5. AMOCO CADIZ chemistry program; surface sediments (Atlas). 



Frequency 

April 1978-October 1978 (Caldec) 

December 1978 

March 1979 

July 1979 

November 1979 

March 1980 

May 1981 

Total 



20 
10 
12 
15 
11 
12 

80 



cations 




Ten Primary Stations 


1,2,3 


He Grande 


4 


St. Michel-en-Greve 


5,6 


L'Aber Wrac'h 


7,8 


Portsall 


9,10 


Trez-Hir 



11-14 Other Impact Stations 

GC/MS 

Stations 3 (lie Grande), 5 (L'Aber Wrac'h), 7 (Portsall) 



51 




a •BIOGENIC 

P • PYROGENlC iCHRONlCl 

AC - AMOCO OIL 



J I I I L_ 



wOh TANlO' 



_l I I I I I L_ 





STATION J 




•lllX 


•:oj* 


• 17X 


ILE GRAND C'cEO' 














J9« 4C 


0900 












a •BIOGENIC 


8 000 












P • PvboGENiC iCHftONiCi 

AC • AMOCO O'L 


9 000 




AC 










4000 














2000 


1 1 


1 


1 


I I 


1 1 


I 1 1 I 1 1 i 




STATION t 










ST M.CMEL £S GREvE 




~ 












:oo 


Il 














»60 


_ 


.AC 












'» 


: 














30 


- j 










AC 






\ 


ac a p 








aC 


40 


i i 


I 


P^^ 
1 


' i 


1 1 


AC 

1 , . Ill 



<I T| 3 79 7 79 U 79 2 SO B.BO 6 8' 



12 78 279 ' "9 M*» 3 80 8 30 i 8' 



FIGURE 3.8. (Left) lie Grande (control) sediment time series. 
FIGURE 3.9. (Right) lie Grande (oiled) and St. Michel-en-Greve time 
series (note scale difference between the two plots) . 



:jlD = r--» 
.VOL e E-»0Q»ACES 

AT L AS -5 

a ■ biogenic 

p • PVROGENlC CmAON'Ci 
■»C • AMOCO 3'L 




J I I I I I I I I I I i i : i 



AC L AgER *RAC M 

C*lO£"-« 
aol*e-:oo PACES 

AT w AS-6 

aoos- ie£B ao; 




i '9 ; '9 : "9 



9 3 90 I 9C 





STATION 7 




AC 






"QHTSAU. 


200 


: 










8 • 3'OGENiC 


<M 


_ AC \. 






V AC 




p • EROGENIC ChRONiC: 
AC ■ AMOCO Oil 


■:o 


: 


AC 






S, AC 




80 


- 










\*C 


40 


i i i 




1 1 


1 1 


1 


*- -• *C 9 P 




STATIONS 










PORTiALL 


500 














400 




AC 












KM 








AC 


AC 




















KM 










V *C 




(00 


1 1 1 




1 1 


1 1 


1 1 


\ ^^-* 9 * AC 

i P 

1 1 1 ' 1 1 



'2 78 ] 79 7 79 'I 79 2 80 8 30 6 Bi 



FIGURE 3.10. Aber Wrac'h sediment time series (left) 
FIGURE 3.11. Portsall sediment time series (right). 



52 



FIGURE 3.12. 



B -BIOGENIC 

J> • PVROGENIC iCHBONiCi 

ac ■ AMOCO OIL 




J I I I L 



12 TS J,T9 8.79 1 1 79 3 80 980 6.8) 



Trez Hir sediment time series. 

AC 



,F 



/' 



Mm 



! j 

, , i.i * 


< 

ill J l« 


1 

J! 


J. 


■ •■i. 





I. k 



FIGURE 3.13. 




Hydrocarbon compositions forming the basis of source 
classification categories. 



53 



TABLE 6. Replication of hydrocarbon concentration data (based 
on December 1978 analyses of two replicates) . 



STATION 


5? 


cr/x 


1 


56 


0.57 


2 


113 


0.08 


3 


1,000 


0.52 


4 


135 


0.60 


5 


401 


0.01 


6 


217 


0.06 


7 


159 


0.10 


8 


358 


0. 21 


9 


18 


0.71 


10 


11 


0.94 



2 130 nq g 



-t-t- 



-t-T- 



t f » 



J L 



FIGURE 3.14. 



Aromatic hydrocarbons, station 3, December 1978; normalized 
to C 3 DBT. 

(A = napthelenes, B = CiN, C = C:N, D = C 3 N, E = C 4 N, F = 
biphenyl, G = fluorenes, H = CiF, I = C 2 F, J = C3F, K = 
phenanthrenes, L = CiPh, M = C?Ph, N = C3Ph, O = Ci*Ph, P = 
dibenzothiophenes, Q = CiDBT, R = C2DBT, S = C3DBT, T = 
fluorene, U = pyrene, V = benzo (a) anthracene, W = chrysene, 
X = benzof luoranthene , Y = benzo (a) pyrene, Z = benzo (e)- 
pyrene, AA = perylene) 



54 



11 OOOng g 




t— i — i — i t I i — I » I I i t 



, i t i — i i t r i i » r t i t f 

ABCDEFQHIJKLMNOPORSTUVWXrZM 



FIGURE 3.15. (Top) Aromatic hydrocarbons, station 3, March 1979; normal- 
ized to C 3 DBT. 

FIGURE 3.16. (Middle) Aromatic hydrocarbons, station 3, July 1979; nor- 
malized to C 3 DBT. 

FIGURE 3.17. (Bottom) Aromatic hydrocarbons, station 3, November 1979; 
normalized to C 3 DBT. 

(See Figure 3.14 for key.) 



55 



-I — i i i i i i i i — i — i — I t ! t — r—r 



1 i i i i i 



ABCDEFGHIJKIMNOPQRSTUVWXYZ 



J L 



77ng ^ 



i i i i — i — i— i — i — i — i — i — i i i — r— i — i — I — r 

ABCOEFGH I J K L M N P R S T Li V w « I Z 



t t I I I 



J L 



5346 4 ng g 



* t i * » i — i — i t t t t I f I — i t r I — i — i — i — i — i — r . 

• BCOEFGH IJKLMNOPQRSTUVWXTZM 



J L 



FIGURE 3.18. (Top) Aromatic hydrocarbons, station 3, March 1980; normal- 
ized to C3DBT. 

FIGURE 3.19. (Middle) Aromatic hydrocarbons, station 3, June 1981; nor- 
malized to C3DBT. 

FIGURE 3.20. (Bottom) Aromatic hydrocarbons, station 5, April 1978; nor- 
malized to C3DBT. 

(See Figure 3.14 for key.) 



56 



4.160 r>g g 



r t t f 



f i t f f t t 



i i i i ■ i i 

CDEFGH1JKLMNOPORSTUVWKYZAA 



I f M 



J L 



480 ng g 



t 1 t i t t t I t t 



i — I I I l — l — l — r 

ABCDEFGHIJKLMNOPOflSTUVWXrZM 



J L 



ffftfi tff 



-M- 



T— f" 



— I 1 I I I 1 P 

ABCDEFGMijKl-MNOPQflSTUVWXYZA* 

I I I II II II 1 



FIGURE 3.21. (Top) Aromatic hydrocarbons, station 5, October 1978; nor- 
malized to C 3 DBT. 

FIGURE 3.22. (Middle) Aromatic hydrocarbons, station 5, December 1978; 
normalized to C3DBT. 

FIGURE 3.23. (Bottom) Aromatic hydrocarbons, station 5, March 1979; nor- 
malized to C3DBT. 

(See Figure 3.14 for key.) 



57 



t i I hn I i i I 



94 n,, , 



ABCOEFGHIJKLMNOPQBSTUV* 

I 1 I II II IL | 



460 fig g 



i i i i i — i — i — i — i — i f 1 t f f i t | | — f— M — i T 1 — I— f 

ABCOEFGHIJKLMNOPORSTUVWXrZU 
I 1 I II II II | 



t t T 



T-+ 



BCOEFGHIJKLMNOPORSTUVWXTZ 



J L 



FIGURE 3.24. (Top) Aromatic hydrocarbons, station 5, July 1979; normal- 
ized to C3DBT. 

FIGURE 3.25. (Middle) Aromatic hydrocarbons, station 5, November 1979; 
normalized to C3DBT. 

FIGURE 3.26. (Bottom) Aromatic hydrocarbons, station 5, March 1980; nor- 
malized to C3DBT. 

(See Figure 3.14 for key.) 



58 



140 ng* 



-I— I 1 I I I I 1 I I I I I I I I I I I ' 

ABC0EFGMIJKLMNOPQRSTUVWXYZAA 



C 3 0BT.280n9g 




W- 



+-r 



Ibcoefghijklmnoporstuvwxtz 

I I I II II II 1 



C3OBT 1 130 rig g 



1 t \ t t 1 I 1 t \ t 



t I t 



t t t 1 I 



ABCDEFGHIJKLMNOPQRSTUWWXYZAA 
I I I II II II 1 



FIGURE 3.27. (Top) Aromatic hydrocarbons, station 5, June 1981; normal- 
ized to pyrene . 

FIGURE 3.28. (Middle) Aromatic hydrocarbons, station 7, December 1978; 
normalized to C3DBT. 

FIGURE 3.29. (Bottom) Aromatic hydrocarbons, station 7, March 1979; nor- 
malized to C3DBT. 

(See Figure 3.14 for key.) 

59 



C30BT:177ng g 



1 * ? » I — I — I I I I 1 I I 1 I — I » 1 I 1 T I I I I I I 

ABCDEFGHIJKLMNOPQRSTUVWirZAA 



J I IL 



C3DBT:75ng 8 



I I I i I — r— i — i — i i I f f I I I f 

ABCDEFGHIJKIMNOPORSTUVWKYZ 



4— r-f 



J L 



C30BT: ling g 



i i i — i — i— i — ii i i r t t r i — i i i r r f , f f i i — r 

ABCOEFGH IJ K LMNOPQRSTUVWXT 2W 
I I I II II II 1 



FIGURE 3.30. (Top) Aromatic hydrocarbons, station 7, July 1979; normal- 
ized to C3DBT. 

FIGURE 3.31. (Middle) Aromatic hydrocarbons, station 7, November 1979; 
normalized to C3DBT. 

FIGURE 3.32. (Bottom) Aromatic hydrocarbons, station 7, March 1980; nor- 
malized to C3DBT. 

(See Figure 3.14 for key.) 



60 



. i i i i i i i i — i i i i i — i i I — r t r T i T — i — i — p 

ABCOEFGM ijk LMNOPOBSTUVWXY zm 

I I I II II II 1 



FIGURE 3.33. 



Aromatic hydrocarbons, station 7, June 1981; normalized to 
pyrene. (See Figure 3.14 for key.) 



JjJHA 



A 




A SATURATES 



... n|L.. *{!*<•> 



,illL 



jp 



i?.!ii^ 






H 



*\ 



£** 



B ABOMATICS 



FIGURE 3.34. TANIO oil. 



61 



marker compounds, the C3 dibenzothiophenes, and C3 and C4 phenanthrenes, 
persist but the pyrogenic PAH compounds have replaced any AMOCO CADIZ 
oil traces at Station 5 in L'Aber Wrac'h. 

The last sampling, June 1981, reveals total disappearance of 
traces of AMOCO CADIZ aromatic marker compounds at stations 3, 5, and 

7. By June 1981 the only unequivocal presence of AMOCO oil is seen at 
station 3 in lie Grande, although it has been extremely weathered. 
Only pentacyclic triterpanes can be linked to the residual AMOCO oil. 
GC patterns suggest that petroleum still affects stations 4, 6, 7, and 

8, but in only minor quantities relative to other inputs. 

Thus, for the most part, less than three and one half years has 
been required to allow normal background inputs to resume their sedi- 
mentary dominance at all but the most heavily impacted (in terms of 
post cleanup oil concentrations) and lowest energy (i.e. most protected 
from waves) environments (i.e. station 3 in the lie Grande). 

Further interpretive details are presented in Atlas et al. (1981). 



3.3 Offshore Sediments (Marchand, CNEXO) 

L'Aber Benoit Sediments (Courtot, U. West Brittany) 

In this phase of the analytical chemical program the levels, the 
persistence, and the precise chemical nature of petroleum hydrocarbons 
in the offshore sediments of the Bays of Morlaix and Lannion were 
examined as well as those of L'Aber Benoit sediments (November 1978 
only) . A summary of the samples analyzed appears in Table 7 and in 
Fiqure 3.35. 

TABLE 7. AMOCO CADIZ chemistry program; 2. Offshore 
surface sediments (Marchand) and Aber Benoit 
sediments (Courtot) . 



Frequency: 

April 1978 6 

July 1978 14 

November 1978 13+7 

February 1979 13 



TOTAL 53 

Locations : 

Aber Benoit (November 1978) 
Baie de Morlaix 
Baie de Lannion 



GC/MS : 

Four Time Series (18 Samples) 



62 




FIGURE 3.35. 



Offshore surface sediment and l'Aber Benoit sampling 
locations (Marchand, Courtot) . 



Hydrocarbon concentrations and source classifications for the 
entire data set are shown in Table 8. Individual aromatic hydrocarbon 
determinations by GC/MS appear for several time series in Tables 9 
through 13 and for two of the L'Aber Benoit samples in Table 14. 

An instructive way of viewing the time series information is 
presented in Figures 3.36 and 3.37. At both the Terenez/ Morlaix and 
lie Grande time series, concentrations increased between April and July 
1978. In the case of the Terenez samples, the increase is due to 
offshore transport of weathered oil as evidenced by 1) an increase in 
absolute concentrations, 2) a decrease in the ALK/ISO ratio, and 3) an 
increase in phenanthrenes (total P, C L , C 2 , C 3 , C 4 P) and dibenzothio- 
phenes, without an accompanying increase in the pyrogenic PAH compounds 
(m/e 202). However, the lie Grande benthic samples show an increase in 
total hydrocarbons along with increases in the aromatics including the 
pyrogenic PAH. This latter finding indicates that both petroleum 
hydrocarbons and combustion-related PAH material are being transported 
to and deposited in the offshore sediments near lie Grande by a similar 
mechanism, most likely in association with suspended matter from 
riverine plumes. Figure 3.38, a plot of phenanthrene and its alkyl 
homologues at the Morlaix Station (Station B) , reveals that while the 
source of the phenanthrenes is petroleum in July 1978, as evidenced by 
the greater abundance of alkylated compounds versus the parent (unsub- 
stituted) compounds, the input in February of 1979 is largely pyrogenic 
(i.e. greater amounts of parent phenanthrene). This illustrates both 
the usefulness of detailed GC/MS-derived data and their subsequent 
presentation in alkyl homologue distribution plots. 



63 



TABLE 8. AMOCO CADIZ sediment sample, source 

classification (GC) (offshore sediments) 



SAMPLE NO. 



(J.J $1 



(J.) ■}) 



AC100 

AC 36 9 

AC426 

AC10 3 

AC 365 

AC4 29 

AC42 

AC138 

AC371 

AC4 53 

AC56 

AC139 

AC 381 

AC458A 

AC458B 

AC127 

AC 370 

AC4 52 

ACL 3 2 

AC362 

AC141 

AC 396 

AC4 3 2 

AC13 4 

AC451 

AC44 

ACL21 

AC 384 

AC112 

AC389 

AC445 

AC10 7 

AC376 

AC436 

AC53 

ACU8 

AC377 

AC4 38 

AC51 

ACU4 

AC379 

AC440 

AC48 

AC125 

AC 378 

AC479 



4/5B 


84.1 


] 4 


90.4 


3. 5a 


252 .9 


3 


3,172.5 


4/5B 


35.5 


3 


133.6 


4,'2/SB 


200.6 


4'2 


39 7.0 


4/5B 


107.9 


4/2 


50 3.4 


5B'4 


37.3 


5/3 


31.6 


1 


109.0 


2'1 


121.7 


2/4 


408.8 


2/4 


502.8 


4 '2 


19.4 


2/4 


97. 7 


2/4 


142.5 


2/4 


16.0 


2 


47.2 


2 


86.0 


4 


5.9 


4/2 


17.2 


2 


54.4 


2 


119. 3 


4 


5.0 


5 


8.1 


4 


4.4 


5 


7.9 


2 


36.9 


2/4 


58.5 


4/2 


18.6 


3/4/2 


48.8 


2/4 


13.8 


4 


41.5 


2/4 


165.8 


4/2 


211.7 


2/4 


24.5 


4/2 


44. 7 


2 


15.6 


2 


39.2 


4/5B 


6.0 


3/4 


13.6 


4 


35.4 


4/2 


26.9 


5B/4 


78. 3 


2/4 


171.9 


4/2 


42.2 


4/2 


50.7 


I 


38.5 


2 


69.1 


2 


17.5 


2 


44.8 


2 


32.1 


2/1 


173.6 


2/4 


122.5 


2 


239.3 


2/4 


56.4 


2/4 


151.1 


2/4 


29.0 


2/4 


64.8 


2 


53.2 


2/4 


176.7 


2 /4 


5.9 


2/4 


8.9 


2 


27.7 


2 


60.6 


1 


28. 9 


2 


31.5 


2/4 


82.2 


2/4 


97.2 


4 


31.9 


4 


132.1 


2/4 


15.8 


4 


32.1 


1/2 


96.4 


1/2 


102.4 


2/4 


56. 4 


2/4 


249.6 


2/4 


27.2 


2/4 


80.7 


2 


103.5 


2/4 


104.5 


2/1 


21.0 


4 


14. 3 


2 


59.1 


2 


27.8 


2 


63.3 


2 


181.0 


2 


36.5 


2 


17.9 



AC40 and 50 series sampled 4/ 
AC100 series sampled 7/78 
AC300 series sampled 11/78 
AC400 series sampled 2/79 



L'Aher Benoit Sediments: 
ABT 
ACC 
AB25 
AB29 
AB16 
AB21 
AB4 



2 


158.2 


180.8 


4 


25.1 1 


29. 3 


2 


29.2 


29.7 


4 


11.6 < 


17.5 


2 


22.2 


28.6 


2 


455.1 


440. 7 


2 


7J.6 


76.9 



64 



TABLE 9. Terenez/Morlaix time series (s'tation A) 



ALIPHATICS Oiq/1) 



AROMATICS (p9/g) 



AC 42 
AC 138 
AC 371 
AC 453 



4/78 

7/78 

11/78 

2/79 



109.0 

408.8 

19.4 

142. 5 



6.1 

11.7 

1.3 

2.8 



0.79 
0.10 
0.10 

0.51 



123.7 

502.8 

97.7 

36.0 



7.4 

17.2 

2.4 

1.6 



ac 42 

AC 138 
AC 371 
AC 453 



nd 
2.9 



Cl« 



10.3 
6.3 



C 2 H 



Cl P 



40.9 
62.5 



115.5 
423.2 



161.0 
730.7 



16.8 
nd 
nd 
nd 



20.1 

37.4 
nd 
1.0 



54.3 

230.2 

4.4 

7.8 



198.9 

905.8 

88.0 

14.8 



125.7 

20.4 

7.4 

5.2 



95.4 

151.4 

9.0 

5.9 



C3 p 



C 4 P 



15 3. 3 

593.5 

12.4 

15.0 



274.8 138.3 

1678.9 882.9 

41.9 27.6 

22.0 21.9 



DBT CiDBT C 2 DBT CjDBT 



B(e)P B(j)P 



AC 42 
AC 138 
AC 371 
AC 453 



19.2 
12.4 

nd 

2.3 



113.6 
383.9 

4.0 
6.7 



714.4 

3363.0 

54.8 

63.8 



1088 
6388 
179.0 
93.5 



195.0 
3.0 
9.1 
4.8 



171.4 

47.1 

7.6 

4.2 



265.7 

77.4 

16.4 

9.6 



298.9 

120.8 

20.9 

9.1 



83.5 

87.2 

9.8 

6.0 



3.7 
3.4 



24.5 

20.3 

1.8 

1.5 



FEYi nd - none detected. 

N - napthalene, C^-C^N - alkylated naphthalenes, P • fluorene, C^P-CjP • alkylated Fluorenes, P • phenanthrene. 
C1-C4P • alkylated phenanthrenea, DBT - Dlbenzoth lophene, CjDBT-C2DBT • alkylated dlbenzoth lophenes , Fl ■ 
Eluoranthene , PYB ■ pytene, CHRY - Cryaene, BP - benzof luotanthene, B(e)P ■ Benzo (e> pyrene, Bta)P • Benzot a) pyrene, 
PERL - perylene. 



TABLE 10. Morlaix time series (station B) 



































DATE 




ALIPHATICS (U9/g] 


ALK/ISO 


AROMATICS ((»j/9> 




SAMPLE 


TOTAL 


RESOLVED 


TOTAL 


RESOLVED 




AC 103 


7/78 




200.6 


12 


6 


2.5 




397.0 


7.4 




AC 165 


11/78 




107.9 


5 


. 3 


5.0 




50 3.0 


7.5 












AC 429 


2/79 




37.3 


2 





0.02 




31.6 


11.9 














N 


V 


C 2 N 


C ]N 


C 4 N 


F 


C l" 


C 2 F 


C 3 F 

301.0 


P 


V 


V 


C 1 P 


V 


AC 103 


17 


18.9 


48.6 


135.9 


220.7 


16. 3 


23.8 


72.8 


117.8 


95.4 


160.1 


312.5 


273.9 


AC 365 


9 


14.4 


33.8 


55.0 


111.2 


9.9 


14.9 


36.9 


81.1 


114.2 


65.3 


58.9 


14 3.3 


101.6 


AC 429 


6 


10.0 


19.7 


28.0 


50. 2 


16.8 


11.6 


23. 3 


7.4 


185.6 


108.6 
PERL 


52.6 


26.0 


34.9 




DBT 


C DBT 


C 2 DBT 


C DBT 


FL 


PYR 


CHRY 


BF 


B(e)P 


BlalP 




AC 103 


15.2 


100.8 


772. 1 


1 348 


240.2 


201.8 


345.2 


350.7 


146.4 


166. 1 


87.0 




AC 365 


11.2 


32.7 


215.2 


440. 3 


202.2 


175.6 


254.0 


324.6 


115. 


110.9 


65.4 








AC 429 


11.3 


7.7 


10.3 


5.0 


125.9 


302.9 


207.4 


202.5 


112.5 


115.0 


17.7 









KEY: nd • none detected. 

N - napthalene, C l -C4H = alkylated naphthalenes, F - fluorene, C1F-C3F - alkylated fluorenes, P 



< -l~ L 4 1 ' " alkylated ph^nanthrenes , 
f luoranthene, PYR * pyrene, CHRY 
PERL - perylene. 



phonanthrene , 



DBT - Dihenzothlophene, CjDBT-C^D 



alkylated d ib«*nzoth lophenes , Fl - 
Crysene, BF = benzof luoranthene , B(e)P ■ Denzo ( e) pyren*> , BlalP " Benzo) a) pyrene , 



65 



TABLE 11. St. Michel en Greve/Lannion time series (station C) 



ALIPHATICS 1)19/9) 
TOTAL RESOLVE! 



AROMATICS (iaj/91 



AC 


14 


4/18 




38.5 




1. 


9 


0.38 




61 


1 


8.6 












AC 


121 


7/78 




17.5 







2 


0.09 




44 


3 


0.6 












AC 


384 


11/78 




32.1 




0. 


5 


0.14 


173 


.6 


1.6 














44 


N 


C l" 


C 2 N 


C 3 H 




c 4 » 


F 


V 




V 


v 


P 


c x p 


V 


C 3 P 


V 


AC 


8.6 


6.3 


12.6 


25.0 




51.7 


nd 


3.3 




12.4 


89.5 


10.9 


29.8 


48. 3 


115.0 


79.4 


AC 


121 


6. 2 


4.8 


10.2 


14.0 




12.4 


1.6 


2.2 




13.7 


57.5 


19.8 


17.7 


55.6 


75.4 


33.9 


AC 


384 


2.4 


2.1 


6. 3 


59.6 




121.1 


nd 


4.2 




35.8 


73.1 


2.8 


28.7 


80.6 


76.6 


36.4 






EST 


C DBT 


C DBT 


C DBT 


PL 


PYR 


CURY 




BP 


B<e)P 


B(a)P 


PERL 








AC 


44 


8.7 


26.6 


253.5 


378. 


9 


17.2 


10.2 


22.7 




31.4 


21.5 


U.l 


6.9 




AC 


121 


3.0 


21.2 


211.1 


348 


,7 


22.1 


17.1 


34.3 




35.1 


15.3 


10.8 


3.2 








AC 


384 


3. 3 


86.2 


337.8 


322 


,5 


3.0 


3.5 


7.5 




6.7 


3.8 


1.5 


0.5 









KEY; nd - none detected. 

N - napthalene, C^-CiN - alkylated naphthalenes, P - fluorene, C1.P-C3P • alkylated fluocenes, P - phenanthrene , 

C 1" C 4 P " alkylated phenanthcenea , DBT - Dlbenzoth iophene, CjDBT-CjDBT - alkylated dlbenzoth iophenes, PI - 

f luocanthene, PYR - pyrene, CURY - Cryeene, BP - benzoEluocanthene , B(e)P • Benzo (e) pycene , B(a)P - Benzo ( a) pyrene , 

PERL - perylene. 



TABLE 12. lie Grande time series (station D) 























ALIPHATICS 


U«3/g) 




APOMATICS 


(M9/9I 


SAMPLE 


DATE 


TOTAL 


RESOLVED 


ALU/ISO 


TOTAL 


RESOLVED 


AC 48 


4/78 


21.0 


0.3 


1.4 


14. 3 




0.6 


AC 125 


7/78 


59.1 


0.9 


0.6 


27.8 




0.3 


AC 378 


11/78 


63.3 


1.9 


0.4 


181.0 




12.9 


AC 439 


2/79 


36.5 


0.8 


5.4 


37.0 




0.1 



AC 48 

AC 125 

AC 178 

AC 439 



4.2 3.1 

0.8 <1.0 



nd nd nd 

143.7 686.2 825. 

112.2 472.5 569. 

<1.0 1.0 nd 



12.8 
nd 



9.9 
286.0 
152.4 

nd 



25.1 

674. 3 

386.7 

nd 



14.9 

63. 3 

11.9 

1.7 



16.5 

109.9 

127.8 

5.9 



20.2 

539.7 

251.7 

5.1 



35.2 

729.0 

473.0 

4.5 



21. 3 
229.0 
227.9 

2.4 



AC 48 
AC 125 
AC 178 
AC 4 19 



1013 
27. 1 



13.2 

785.4 

274.0 

2.5 



80.7 
24 20 
1481 

12.4 



145.6 
2917 
1945 
15.5 



19.8 

55. 2 

3.8 

<1.0 



18. 3 

19. 4 
9.4 

<1.0 



14.1 

107.7 



17.2 
99.0 



16.7 
52.7 



6.1 

16.0 

2. 2 

1.0 



44.7 

6.1 

2.0 

nd 



KEY: nd • none detected. 

na - not analyzed. 
N - napthalene, C^-C 4 N • alkylated naphthalenes, F " fluorene, O^F-CjF ■ alkylated (ltiorenes. P • phenanthrene, 
C1-C4P ■ alkylated phenanthcenea, DBT • D tbenzoth Iophene, CiDBT-CjDBT ■ alkylated dlbenzoth iophenes , Fl - 
f tuof anthene, PYR ■ pyrene, CHRY ■ Ctysene, BF ■ henzof luoranthene , B(e)P - Benzo ( e) pyr ene, BlalP ■ Ben*o ( al pyi ene, 
PERL - pecylene. 



66 



TABLE 13. Lannion I and II time series. 



LANNION I TIME SERIES (STATION El 



SAMn.E DATE 



AC 107 7/78 nd 8.7 32.8 87.4 167. 
AC 4 36 2/79 1.6 1.9 2.9 1.9 nd 



4.5 10.1 34.1 95.3 22.8 41.3 60.9 117.7 71.1 

nd nd nd nd 3.7 5.9 5.1 2.3 nd 



PVR CHRY BF BlelP B(alP PERL 



AC 107 9.9 75.4 295.6 416.4 23 

AC 436 nd 1.5 22.4 40.2 1.6 



19.6 
1.9 



42.6 20.6 19.4 9.5 
12.3 3.7 2.5 2.0 



LANNION II TIME SERIES (STATION PI 



SAMPLE DATE 



c l p 


C 2 P 


V 


C 4 P 


9.3 
7.3 


19.9 
7.8 


37.1 
17.9 


21.0 

7.8 



AC 118 7/78 nd nd 

AC 377 11/78 5.8 4.1 



9.5 16.3 26.3 

7.3 6.1 nd 



1.0 
1.5 



2.2 5.0 18.6 7.9 

1.3 2.3 9.0 12.5 



BlelP B(a)P 



AC 118 
AC 17 7 



10.2 


90.1 


181.2 


10.6 


e.s 


nd 


nd 


nd 


nd 


nd 



22.6 

n<3 



12.8 
nd 



KEYi nd ■ none detected. 

na • not analysed. 
N - napthalene, C1-C4N - alkylated naphthalenes, F - fluocene, C^F^^r - alkylated fluorenes, P - phenanthrene , 
C1-C4P - alkylated phenanthrenes, DBT - Dlbenzothlophene, C 1 DBT-C2 DBT * alkylated dibenzothlophenes , Fl - 
f luoranthene, PYR - pyrene, CHRY - Crysene, BF • benzof luoranthene, Bfe)P ■ Benzo (e) pyrene , B(a)P ■ Benzo ( a) pyrene , 
PERL • pecylene. 



67 



TABLE 14. L'Aber Benoit GC/MS results. 





AB 25 


AB 21 


N 


nd 


3 


Citi 


nd 


11 


C 2 N 


4 


104 


C 3 N 


30 


220 


C 4 N 


55 


307 


F 


- 


4 


c lF 


4 


25 


C 2 F 


11 


113 


C3F 


59 


311 


P 


3 


14 


C L P 


30 


50 


c 2 p 


54 


440 


C 3 P 


84 


800 


C 4 P 


54 


450 


DBT 


5 


29 


CiDBT 


34 


200 


C 2 DBT 


166 


1350 


C3DBT 


195 


2000 


Fluoranthene 


6 


19 


Pyrene 


4 


23 


Benzanthracene 


nd 


69 


Chrysene 


15 


53 


Ben zo fluoranthene 


11 


43 


Benzo(e) pyrene 


7 


24 


Benzo (a) pyrene 


4 


12 


Perylene 


2 


10 


?l (Total) 


29 


460 


F 2 (Total) 


30 


440 



KEY: nd = none detected, 



68 




8 MO 



0« "» 





FIGURE 3.36. 
FIGURE 3.37. 
FIGURE 3.38. 



(Upper left) Terenez/Morlaix sediment time series. 
(Upper right) Offshore lie Grande sediment time series, 
(Bottom) Alkyl homologue distributions of phenanthrene 
series . 



69 



3.4 Sediment Cores (Ward, Montana State University) 

An extensive series of sediment cores was obtained and analyzed by 
GC and selected samples analyzed by GC/MS for detailed aromatic hydro- 
carbon profiles. Samples were analyzed in support of anaerobic petro- 
leum biodegradation experiments (e.g. Winfrey et al . , 1981). Three 
impacted sites and three control sites representative of beach, aber 
(estuarine) and marsh environments were selected (Table 15, Fig. 
3.39). 



TABLE 15. AMOCO CADIZ chemistry program, inter- 
tidal cores (Ward) . 



Frequency: 

December 1978 16 

March 1979 28 

August 1979 16 

November 1979 10 

May 1980 12 

Total 82 

Locations : 

Oiled : 

AMC-4 (Portsall) - beach 

L'Aber Wrac'h - estuary 

He Grande (South-Oiled) - 
marsh 

Unoiled: 

He Grande (North-Control) 
marsh 

Trez Hir - beach 

Aber Ildut - estuary 

Other Stations: 
Station 11 
Station 12 
Baie de Morlaix 
Port de Concarneau 

GC/MS: 

Several selected cores 



70 




lit . ,H»NMt 




ALSO POH) U£ tUNCAHNt AU 



FIGURE 3.39. Sediment core sampling locations (Ward). 



The basic set of data, where GC and GC/MS data exist, is illustra- 
ted by the data in Table 16. However, secondary data products are 
presented here to illustrate the basic findings of this program segment. 

Illustrative GC traces from March of 1979 are shown in Figures 
3.40 and 3.41. While the hydrocarbon composition of the control 
estuary (L'Aber Ildut) is comprised mainly of biogenic compounds the 
marsh mudflat and beach both contain anthropogenic inputs. The lie 
Grande "control" has been impacted by the AMOCO oil as its GC profiles 
closely resemble those for weathered oil. However, the Trez Hir 
(beach) site consists mainly of compounds of a pyrogenic origin. The 
impacted sites all illustrate AMOCO oil in various states of weather- 
ing, the lie Grande (marsh) site containing the best "preserved" oil. 
This is also indicated by secondary treatment of some of the core 
aromatic data (Fig. 3.42) where oil in both L'Aber Wrac'h and lie 
Grande appears to be less weathered at depth. 

Data from the three impacted cores and the control core are shown 
in Figures 3.43. 3.52, 3.58, and 3.63. Each figure depicts the depth 
of penetration of AMOCO CADIZ oil throughout the December 1978 to May 
1980 time period. The C3P/C3DBT ratio is presented as is the level of 
the non-petrogenic fluoranthene + pyrene (m/e = 202) total. 

Accompanying these figures are graphs of the down-core variations 
in gross hydrocarbon parameters (i.e. fj_, f2, ALK/ ISO ratio) and 
detailed aromatic compound families. Figures 3.44 to 3.51 depict 
details of the L'Aber Wrac'h cores, Figures 3.53 to 3.57 the He Grande 



71 



TABLE 16. L'Aber Wrac ' h sediment core (March 1979). 







SAMPLE 


DATE 




ALIPHATICS (uq/q 




ALU/ 1 SO 


AROMATICS 


{uq/ql 












TOTAL 


RESOLVED 


TOTAL RESOLVED 






0-5 cm 


3/79 




530.0 


27 


8 




565 


.0 


16.4 








5-10 


3/79 




113.7 


8 


4 




318 


.4 


19.4 












10-15 


3/79 




95.4 


2 


8 




lie 


.1 


4.0 












15-20 


3/79 




4.4 


1 


1 




46 


.5 


4. 4 












20-25 


3/79 




10. 1 


1 


6 


















N 


C lN 


C 2 N 


C 3 N 


C 4 N 


F 


Cl F 


C2 F 


CjF 


P 


ClP 


W 


•V 


<v 


0-5 


20.4 


23.0 


42.5 


292.2 


288.9 


18.9 


53.7 


137.2 


434.4 


100.6 


200.5 


294.0 


516.6 


120 


5-10 


2.6 


11.9 


50.3 


181.6 


426.7 


13.4 


40.8 


226. 3 


440.2 


156.5 


185.0 


278.4 


348.7 


102 


10-15 


4.9 


10.7 


21.8 


87.4 


159.1 


9. 3 


24.5 


91.2 


176.1 


134.1 


101.3 


165.6 


153.6 


117 


15-20 


5.8 


11.5 


20.5 


36.7 


78.0 


10.6 


13.0 


14.3 


86.0 


146.1 


eo.7 


50.5 


21.3 


35 


20-25 


nd 


2.6 


14.3 


17.9 


nd 


6.9 


7.0 


25.0 


25.5 


100.0 


67.4 


29.3 


10.1 


26 






DBT 


C l DBT 


C 2 DBT 


C3OBT 


FL 


PYR 


CHRY 


BF 


B(e)E 


B(a)P 


PERL 








0-5 


40.0 


87.5 


1466 


1598 


116.6 


157.7 


170.4 


136. 3 


89.0 


64.8 


24.5 






5-10 


24.3 


135.6 


1360 


830.7 


132.8 


172.2 


185.2 


219.7 


124.2 


128. 2 


33.7 








10-15 


17.4 


93.7 


498.4 


491.6 


156.4 


178.6 


174.4 


230.9 


118.6 


137.0 


36.2 








15-20 


10.7 


16.7 


32.3 


65.2 


164.3 


155.7 


169.6 


215.3 


100.2 


122. 3 


29.5 








20-25 


5.0 


8.0 


10.1 


5.0 


98.9 


74.9 


93.2 


76.7 


94.3 


105.6 


24.4 



































KEY: nd - none detected. 

N • napthalene, C1-C4N «• alkylated naphthalenes, F » fluorene, ClF-CjP - alkylated fluorenes, P - phenanthrene , 

< -l" < -4 p " alkylated phenanthr enes , DBT * Dibenzoth lophene , C^DBT-C^DBT ■ alkylated dibenzothiophenes , Fl ■ 

f luocanthene, PYR » pyrene, CHRY ■ Ccyaene, BF ■ benzof luor anthene , B(e)P - Benzo (e) pyrene , B(a)P ■ Benzo (a) pyt ene , 

PERL =• perylene. 



1 .11 i 1,1, .1 t .ttt.it v Mn.Mf.n 



mP^A( 



..ill M.itsl- M'.HM.ii 



J^ilw^ui^^ 



u 1 u,i, .,1 n, B ii 




cUiu'-'A^ 



k 



iif I 1 v Mntlll <i 



Ml, 



(Ml 1 111 1 S.1I1 M..i ill M<> 



y 



p..^. 



u 



11 1 1 Hi.. 



, Ail* 



V 



K.\M.\ 



FIGURE 3.40. Saturated hydrocarbons in sediments from oiled and control 
sites. 



72 



(A| <>ii«i Estuary Mu.ilidt 



I S Inlmvl ^l.i-la.l 






J 




IC) Oilwl '-..ill Maul. M1..111..1 



IUhU 1J-" 




tEl Oilwl Bej.li 



IBI Control Esiujty MihIIIaI 



1 jJppJUilJUUL. , 



(Dl Cnnlrol Sjll Ma.sJi Mu.lll.il 



L...jjwI 



t F J Ciit.litil Uracil 



m*&*\ 



iHUm 



M, 



: -00-, 



id 



AMOCO CA0I2 O'L 
„, ^•••'•«ct Mount 
t 30-161 



n 



T AflE3 .V9ACM 
Aor-i 27 1978 



!0 

Ik 



N CiCjC 3 C 4 » C,CjC]Ci C,C;Cj 

-1 I I 

I P>i*n*nfftr«n*t O'0»«*»- 



i -m-Hi i un 



IL6 GSANDE 'SOUTH 
Mire* 1979 
0-Scm 



n 



M 



» CCjCjC, • C,C;CiCi r> C,C,Cj 

' ' ' I 



ABEfl '.VBACM 

M«rcri '979 

0-5 em 



\ 



N CiCjCjC* » C|C;C]Ci CiCjCj 
I I 1 1 



^TMl i l 



'BOO 000 

\ 
s 
s 

\ 



' C,CjCjC« * CCJCJC4 O C,CjCj 



■'Mtf'ntt^n »*.«»Aff>r.* 



ILE GRANDE (SOUTH 
Mircn 1979 
15-ZOcm 



ns 



n 



1 S 

r 1 ^ 

Mfc 

11 



ABES WRaCh 
Mire* 19:9 
10-15 cm 




LU 



: 



N C1C3C3C4 * CiCjCjCj O C.CiCj 



* C,CiC]C« » CiCjCaCi O CiCrCj 



FIGURE 3.41. 
FIGURE 3.42. 



(Top) Aromatic hydrocarbons in sediments from oiled and con- 
trol sites. 

(Bottom) Comparative aromatic compound concentration pro- 
files derived from GC/MS-histogram presentation. 
73 



occEMeea 1979 



WAflCM '979 




-300 
-300 
-300 




C)" ; . . 



AUGUST -979 



NCvEWBE" '9'9 



CjC »Jl« ft )i 









CjDBT 



r^ 



4M0C0 CADIZ OIL 

PYRQGENiC 
BIOGENIC 



FIGURE 3.43. 



Aber Wrac ' h 
sediment cores. 



200 



400 



ug g 



600 



800 






!•[ 



Aromallci 



Salurale< 



f 



— ALK ISO | 



220 



\ 



20 



\ 



\ 



50 



1.0 



\ 



ALK ISO 



4.75 



1000 



no g 



2000 



3000, 8000 




DBT — 

202 228 TS2 



FIGURE 3.44. (Left) Aber Wrac'h core, December 1978. 
FIGURE 3.45. (Right) Aber Wrac'h core, December 1978. 



200 400 " S ° 600 



800 



1000 



ng g 



2000 



3000 



Aroma lie s 



10r 



Salurilis 

ALK ISO : io 






= 



S20 




N- 
DBT- 



202 228 252 



0.50 



1.0 



1.50 



2 



5.0 



ALK ISO 
FIGURE 3.46. (Left) Aber Wrac'h core, March 1979. 
FIGURE 3.47. (Right) Aber Wrac'h core, March 1979. 



74 



200 



jg g 

400 600 



10 



20 



r 



\ 10- 



. Saturates 



0.50 



Aromitics 



1.0 1.50 



ALK/ISO 



20 



400 " a " 600 800 




Aromitics 



Sitariln- 



ALK ISO 

FIGURE 3.48. (Left) Aber Wrac'h core, August 1979. 

FIGURE 3.49. (Right) Aber Wrac'h core, November 1979 



ALK/ISO 



ALK/ISO 



0.50 1.0 1-50 2.0 



2.60 



10 



= 20 



1000 '"'MOO 



3000 



P 
DBT 



0.50 



1.0 



1.50 



202 228 252 



2.0 





200 


400 "' ■ 600 


800 




1 




\ 




' 


-10 




^ 


^ 


1 

! 


20 




Aromitics - 










" 








~ ALK ISO i 




0.50 


1.0 1.5 


2.0 


"■ 



FIGURE 3.50. 
FIGURE 3.51. 



ALK/ISO 

ALK/ISO 

(Left) Aber Wrac'h core, November 1979. 
(Right) Aber Wrac'h core, May 1980. 



DECEMBER 1978 



MARCH 1979 



IPHC CjP 2021^9 V 

.>.g. 91 C3O8T 





1PHC C3P 202119 9 

vq 9) C3O8T 



350 
310 
230 



FIGURE 3.52. 



AUGUST 1979 



IPHC C3P 202lng,g> 

iiig/91 C3OBT 



0-5 


^M 


5-10 




10-15 




15-20 





Mv 1 ' 






I 100 
550 

100 



AMOCO CADIZ OIL 

PYROGENIC 

BIOGENIC 



130 
170 



0-2 mm 


,1 


-10 mm 




1-2 cm 




2-3 cm 


^ 


^ 


3—1 cm 




1-5 cm 




5-lOcm 





I?MC 
tpg.gl 

5900 

3100 

3 300 
3 700 
22000 
3300 
8810 



C3P 202(^99) 

C3O8T 



330 

1 100 



lie Grande 
(oiled) sedi- 
ment cores. 



75 



no g 

400 600 




Silaralis 
ALX ISO 



ALU ISO 



ALK ISO 



1000 "B / » 2000 



OBT ' I 

202 228 2?2 



200 400 *' B 600 800 




Aramllci 



Silinlii ' 

ALK/ISO • 



0.50 1.0 1.5 2.0 63.25 

1 1— »M ' 



ALK/ISO 



10 



120 



2000 4000 J|/| 8000 6000 ,15000 



0.50 



Annuities 



Silinlii 



ALK/ISO . 



1.0 



1.50 



2.0 



2.50 



ALKISO 



FIGURE 3.53. 

FIGURE 3.54. 

FIGURE 3.55. 

FIGURE 3.56. 

FIGURE 3.57. 



(Upper left) lie Grande south core, December 1978. 
(Upper right) lie Grande south core, March 1979. 
(Middle left) lie Grande south core, March 1979. 
(Middle right) He Grande south core, August 1979. 
(Bottom) He Grande south core, May 1980. 



76 



FIGURE 3.58. AMC-4 sediment cores. 



DECEMBER 1979 



IPHC 



0-5 




5-10 




10-15 




15-20 




20-25 


« 



C30BT 







MARCH 


■■" 


















IPMC 
Uig 9) 

200 

150 

130 

SO 


CjP 
C3O8T 

30 
38 


202. ng g, 




0-5 
5-10 
10-15 

15-17 




: 


1 




- 


a. 
3 




- 




v 










i\ 


12 



AUGUST 1979 |NEW .NPUTl 



NOVEMBER '979 



0-5 


III ■ 

,i:;li : l 


5-10 




10-15 




15-19 


ii 

III: 



SM 



AMOCO CADIZ OIL 

PYflOGENIC 

BIOGENIC 



IPHC 


C3P 


2021 


lfl'*l 






IPHC 


C 3 P 


202iig Sl 


wg g) 


C3OBT 
33 


25 




a. 


0-5 




Wg'9» 


CjOBT 
28 




46 000 


■ ||i: 

. 1 1 


120 


32 










8 800 


35 


2S 














680 


- 


- 














1,100 


- 


- 








MAY 1980 







o-s 

8-13 R 





» 


\> 



IPMC C3P 202i^g 31 

lpg'91 C3O6T 



cores, Figures 3.59 to 3.62 the AMC-4 cores and Figure 3.64 a L'Aber 
Ildut core. Most of the cores were subdivided into sections of 3-5 cm 
in depth. However, two finer subdivisions from L'Aber Wrac'h - Novem- 
ber 1979 (1 cm segments down to 5 cm) , lie Grande - May 1980 (top 10 mm 
subdivided plus 1 cm sections down to 5 cm) were made. 

Penetration of oil was observed down to 10-15 cm in L'Aber Wrac'h 
sediments with concentrations decreasing with depth when viewed in 5 cm 
sections. Note however, that while petroleum aromatics were decreasing 
in concentration with depth, the pyrogenic PAH compounds increased with 
depth. Finer subdivisions of the core indicate greater variation 
within the core than the 5 cm sections would indicate (Fig. 3.52). 

An increase in vertical penetration of oil was observed for the 
lie Grande site between December 1978 and March 1979. A fresher layer 
of oil is found at the 15-20 cm depth (see Figs. 3.53 and 3.54) where 
naphthalenes, dibenzothiophenes, and to a lesser extent phenanthrenes, 
are more abundant than in surrounding layers. The gross hydrocarbon 
concentration changes at this level are not nearly as dramatic as are 
the petroleum aromatics, thus confirming that the "bulge" in Figure 
3.42 is due to the less weathered nature of the buried oil. The finely 
divided May 1980 core (Fig. 3.52) indicates a higher petroleum content 
probably owing to a secondary input or to sampling variability which 
resulted in much higher levels (5-10 parts per thousand) during May 
1980. The down core distribution of hydrocarbons is quite non-uniform 
as well with a preserved layer of fresher oil at 3-4 cm. 



77 



The AMC-4 cores appear dominated by well mixed AMOCO oil through- 
out the 0-20 cm depths. Lesser amounts of pyrogenic PAH vis-a-vis the 
Aber and marsh sediments are due to the sandy nature of the AMC-4 
samples. A new large input of oil is seen in August 1979 resulting in 
some down-core concentration variation. 

Chemical descriptions of the "control" site cores are shown in 
Figure 3.63. Note that non-petroleum PAH are widely observed in these 
sediments and that non-AMOCO CADIZ-impacted sediments contain 
50-300 ppm of chronic hydrocarbon pollutants. 



200 400 " 8/| 600 800 




Arositle* 



Saluratas - 20 



UK ISO - 



1.0 



1.5 2.0 




ALK ISO 



200 



jo g 

400 600 



\ 



Aromalics 



- Saturates 



ALK ISO 



50 1.0 150 



ALK ISO 



ng g 
1000 2000 



200 



400 ut ' 3000 5000. 40000 






10 
1 . 



20- 



P 



-0BT 
202 228 252 



10 



20 




Aromalics 



Salurilis 
ALK ISO 



0.50 1.0 1.50 2.0 

ALK ISO 



FIGURE 3.59. 

FIGURE 3.60. 

FIGURE 3.61. 

FIGURE 3.62. 



(Upper left) AMC-4 core, December 1978. 
(Upper right) AMC-4 core, March 1979. 
(Lower left) AMC-4 core, March 1979. 
(Lower right) AMC-4 core, August 1979. 



78 



A3£B 'LOUT 



iLE GAANDE ,NOPTh 



MAflC" '979 



wascm 1979 



IPHC C3P 202f»9-9l 

iu9 9) C3DBT 




IPHC C3P 202,^gi 

\uq gl C3OBT 




MARCH 1979 



- PHC C 3 P 202lnq,g 

iitq 9) C3D8T 



0-5 . 

5-10 
10-15 



^ 



2 6 640 



AMOCO CADIZ OIL 

PYHOGENIC 

BIOGENIC 



FIGURE 3.63. Miscellaneous sediment cores. 







.000 ng/0 


2000 








\ 










10 


l\ 


\ 

V 






- 


lilt 


\ 


\ 


*\ 


P- 


N 
DBT . 



202 228 252 



FIGURE 3.64. Aber Ildut, March 1979. 



79 



3.5 Oysters and Plaice (Neff, Battelle) 

Samples of oysters and plaice from several impacted regions 
(L'Aber Wrac'h, L'Aber Benoit and Baie de Morlaix) and two supposedly 
unimpacted locations (Brest and Loctudy) were analyzed (Table 17, 
Figure 3.65) . 

The results of the oyster time series analyses are summarized in 
Table 18. Both the "gross" hydrocarbon parameters as well as the 
petroleum-associated aromatic hydrocarbons are presented. Though not 
"clean", the control (Brest) oysters are several times lower in gross 
concentration throughout the time period and an order of magnitude 
lower in aromatic hydrocarbon content than either of the impacted 
sites. It is not apparent if the levels have decreased substantially 
in either of the Abers, though aromatic levels are 3 to 4 times lower a 
year and a half after the spill. For comparison, levels of several 
of the non-petrogenic PAH components (i.e. m/e 252) are presented. 



TABLE 17. AMOCO CADIZ chemistry program; oysters and plaice (Neff) 



Frequency: 




December 1978 


4 


April 1979 


6 


July 1979 


7 


February 1980 


9 


June 1980 


11 



Total 37 



Location: 

L'Aber Benoit - Oysters; 
Plaice Muscle/Liver 

L'Aber Wrac'h - Oysters; 
Plaice Muscle/Liver 

Loctudy - Plaice Muscle/Liver; 
Oysters (7/79 only) 

Brest - Oysters 

Baie de Morlaix - Oysters 
(7/79 only) 



GC/MS 

L'Aber Benoit Oysters 
L'Aber Wrac'h Oysters 
Control Oysters 

80 




ALSO LUCIUtl. 



FIGURE 3.65. Oysters and Plaice sampling locations. 



TABLE 18. Petroleum hydrocarbons in oysters (Crassostrea gigas) 



















PETROLEUM 




DBT 








HYDROCARBONS 


P a 


252° 


LOCATION 


DATE 


(ug/g) 


(ug/g) 


(ug/g) 


(ug/g) 


L'Aber Wrac'h 


12/78 


660 


12 


22 


0.04 




4/79 


1,200 


15 


12 


0.02 




7/79 


590 


5 


10 


0.03 




2/80 


820 


10 


16 


0.60 




6/80 (#1) 


440 


4 


6 


0.40 




6/80 (#2) 


560/570 d 


- 


- 


- 


Brest 


12/78 


260 


4 


4 


0.07 


(control) 


4/79 e 


1,100 


11 


10 


0.01 




7/79 


91 


0.3 


0.3 


- 




2/80 


150 


0.4 


1.1 


0.6 




6/80 


93 


0.6 


0.7 


0.2 


L'Aber Benoit 


12/78 


690 


- 


- 


- 




4/79 


800 


15 


15 


1.0 




7/79 


- 


- 


- 


- 




2/80 


430 


14 


9 


1.1 




6/80 


520 


3 


5 


0.2 



a Sum of phenanthrene and alkyl phenanthrenes. 

b Sum of dibenzothiophenes and alkyl dibenzothiophenes. 

c Sum of m/e = 252. 

^Replicate analyses. 

e Origin of sample unclear. 



81 



The GC traces for the impacted oysters are consistent throughout 
the study. The aromatic hydrocarbons (Figs. 3.66, 3.67) are dominated 
by the alkylated dibenzothiophenes and alkylated phenanthrenes through- 
out. The alkyl naphthalenes and fluorenes, significant in December of 
1978, are removed from the tissues by June 1980. Aromatic hydrocarbons 
in the control oysters (Fig. 3.67), while less concentrated, are 
dominated by the same compound series, though the compositions in the 
controls remain consistent with time (i.e. no loss of fluorenes or 
naphthalenes) . GC/MS traces of the oysters confirm the importance of 
the dibenzothiophene series (Fig. 3.68). 

Saturated hydrocarbon GC traces are illustrated in Figures 3.69 
and 3.70 for impacted and control oysters respectively. The saturates 
of the L'Aber Wrac'h samples are dominated by branched alkanes (e.g. 
isoprenoids) and a large low boiling UCM (Cn - C20) • Tne U ^M in the 
controls is less pronounced yet significant, and while the isoprenoids 
are abundant indicating some weathered petroleum, a higher boiling 
smooth n-alkane distribution (i.e. paraffins, n-C2o ~ n ~C3o) is of 
equal importance. Figures 3.71 to 3.76 show some representative aroma- 
tic and saturated fraction data from oyster samples taken from L'Aber 
Wrac'h and the control station. 

The results of the plaice analyses are summarized in Table 19. 
The absolute concentration data does not address the source of the 
observed levels which for the most part are not linked to AMOCO CADIZ 
oil. The muscle tissues exhibit some petroleum-like GC traces includ- 
ing some UCM material and smooth n-alkane distributions with the 
presence of UCM material primarily responsible for the higher levels 
shown in Table 19. Liver tissue in all samples is much higher in 
absolute hydrocarbon content (Figs. 3.77 and 3.78). The f^ (saturated) 
traces are characterized by a high molecular weight UCM (cycloalkanes) , 
and an n-alkane distribution in the C22 to C23 region, while the 
f2 traces are characterized by polyolefinic material, including 
the biosynthesized compound squalene. These f± and f2 distributions 
are characteristic of fish livers from many geographic regions (Boehm, 
1980; Boehm and Hirtzer, 1981) and are probably not related to any 
particular spill event. 



82 





FIGURE 3.66. 



Aber Wrac'h impacted oysters - aromatic hydrocarbons; A 
December 1978; B - June 1980. 




t 



,, |... . J» if 



\,k^ 



P 



JpftJ 



**d 



■ ' i- ill 



1 1 ill I 



FIGURE 3.67. Brest control oyster - aromatic hydrocarbons; A - December 
1978; B - June 1980. 
83 



b c 



J 



l| 



I "II 







mi 

ill 



j 



lit- 1 



|! ''*Ui 



v«vn 



f 



Wj 



CvWluia 



. i i i i i i i i i i i i i i i i ; i i i i i i i i i i , i i i i i i i 
S id IS Si_ 52 £3 £5 2a 



m/e 



m/8 



m/e 



Lja.i 



t: 



E 



f 




aujIl 



La 



U U 

1 \K 



Y_^rar>* 



N<"\AaWV/u_ 



A\-<A .11, 



JU 



■ft- -3«- 



;1_^XAA^^JIA^ VVaJV^ ^ ^AA^-v. 



i 1 r 



i i i 



-jC 1b 17 19 ig 43 41 43 *-j 44 45 <h 4"> 43 -4 9 ga Si S? 



FIGURE 3.68. Section of GC/MS total ion chromatogram of aromatic fraction 
of oyster sample illustrating major alkyl dibenzothiophene 
(DBT) components (a = CiDBT: b - C2DBT; C = C3DBT). 



84 




*"" -' . 




'IGURE 3.69. Aber Wrac'h impacted oysters 
December 1978; B - June 1980. 



saturated hydrocarbons; A 



•.w» 



■if, 

3 » 




lit, 



Km 




>d 5f 



M~.., 



jM JiJ L ^ 






JMI 



U 



iiiii 



FIGURE 3.70. Brest control oysters - saturated hydrocarbons; A 
ber 1978; B - June 1980. 



Decem- 



85 



-*■ 



I I I I ' I I I I I I I I I I I r I f I I t f f I f f f 

ABCDEFGH IJ K LMNOPQRSTUVWXYZU ABCDEFGH IJ K LMNOPQRSTJVWXYZU 

FIGURE 3.71. (Left) Aber Wrac'h, Crassostrea gigas , aromatic hydrocarbons, 
December 1978. (See Figure 3.14 for key.) 

FIGURE 3.72. (Right) Aber Wrac'h, Crassostrea gigas , aromatic hydrocar- 
bons, June 1980. (See Figure 3.14 for key.) 



TABLE 19. Summary of Plaice hydrocarbon data. 









HYDROCARBONS 


STATION 


DATE 


TISSUE 


(pg/3 dry wt) 


L'Aber Wrac'h 


5/79 


Muscle 


90 




7/79 


Muscle 


33 




2/80 


Muscle 


77 




6/80 


Muscle 


186 




7/79 


Liver 


1,350 




2/80 


Liver 


1,200 




6/80 


Liver 


1,640 


L'Aber Bene- it 


5/7 9 


Muscle 


147 




7/79 


Muscle 


17 




2/80 


Muscle 


104 




6/80 


Muscle 


48 




7/79 


Liver 


1,030 




2/80 


Liver 


1,860 




6/80 


Liver 


2,500 


Loctudy 


4/79 


Muscle 






2/80 


Muscle 


41 




6/80 


Muscle 


38 




2/80 


Liver 


1, 300 




6/80 


Liver 


1,900 



86 



I I I I I I I I 

A8C0EFGH IJ K LMNOPQBSTJVWXYZi 



Cio ■ 


No'""» A.jn* C -10 


C|i ■ 


Nof-n* Xtktnt C— 1 1 


etc 




FAR 


: j -titrt 


PBlS 


• ?• nana 


•MY 


asvunc 


1330 


'550 • 'ioO'fnO'Oi 



r r r i f r r i i i p p f > i i i i i 

ABCDEFGHIJ KLMNOPQRSTUVWXrZ AA 68 



I , I I I I M I I 

ABCDEFGHIJ KLMNOPQRSTUVWIVZAABB 



1 M > P t P M f P f I f I I f P I P f P P T P I I i I 

ABCDEFGHIJ KLMNOPORSTUVWXYZAABB 



FIGURE 3.73. (Upper left) Brest, Crassostrea gigas , aromatic hydrocarbons, 
December 1978. (See Figure 3.14 for key.) 

FIGURE 3.74. (Upper right) Aber Wrac'h, Crassostrea gigas , saturated hydro- 
carbons, December 1978. 

FIGURE 3.75. (Lower left) Aber Wrac'h, Crassostrea gigas , saturated hydro- 
carbons, June 1980. (See Figure 3.74 for key.) 

FIGURE 3.76. (Lower right) Brest, Crassostrea gigas , saturated hydrocar- 
bons, December 1978. (See Figure 3.74 for key.) 



87 



AROMA IK S 



& 




¥ ^L 



i 



SATURATES 



4-1 



j! 




M 



FIGURE 3.77. Plaice Liver, control. 



AHUMAl ICS 



I , 



j. J III., j IuIm»»-» '*' 







•i'. 1 



■»^ 



'.AlunAi is 



J; 



m 



i 



a 






M)„ , 



FIGURE 3.78. Plaice Liver, oil-impacted. 



88 



3.6 Oysters and Fish (Michel, ISTPM) 

An analytical chemical program in support of the early post-spill 
(March 1978 - March 1979) programs of the Institute Scientifique et 
Technique des Peches Maritimes (ISTPM) was undertaken (Tables 20 to 22 
and Fig. 3.79). Samples of freeze-dried oysters and fish (various 
species) were analyzed by GC and several samples by GC/MS. The results 
of the analyses are tabulated in Tables 23 to 25. Based on the nature 
of the GC traces, sources of observed hydrocarbon distributions are 
derived: fresh AMOCO CADIZ oil, weathered oil, and biogenic hydrocar- 
bons. Often combined sources are apparent (e.g. weathered oil/biogenic 
hydrocarbons) . 

Two oyster time series, summarized in Table 26, indicate that 
initial heavy oil impacts on the tissues are reduced over time but 
certainly not eliminated. GC traces illustrating the change in aroma- 
tic hydrocarbon composition with time (Fig. 3.80) show that again the 
alkylated phenanthrene (P) and dibenzothiophenes (DBT) dominate the 
assemblage through February of 1979. 

Fish tissues do not reveal significant oil impacts. For the most 
part the hydrocarbons consist mainly of biogenic compounds (e.g. 
olefins) with an occasional UCM and again the presence of DBT and P 
compounds probably, though not definitely, related to AMOCO CADIZ oil 
(see Table 24) . 

An attempt at decontamination via oyster transplantation yielded 
lower levels of hydrocarbons (Table 23; sample 143) indicating that 
once removed from a polluted substrate the oysters can depurate their 
oil burden significantly. 

Thus the oysters exhibit similar area-wide uptake of AMOCO oil, 
initially at the 3000 ppm level, rapidly reduced to the 300-700 ppm 
level and to the 50-200 ppm level a year after the spill. However, 
identifiable oil residues remain. Fish samples show only sporadic 
uptake of any oil indicating that the oil has not significantly impac- 
ted coastal fish, or that once impacted the fish rapidly depurate 



and/or metabolize petroleum 




FIGURE 3.79. Oysters and fish sampling locactions. 

89 



TABLE 20. AMOCO CADIZ chemistry program, f reeze-dried fish and oysters 
(Michel, ISTPM) . 



Frequency 








March 1978 


1 


Oyster 




April 1978 


1 


Oyster + 1 


1 Fish 


May 1978 


1 


Oyster + 6 


i Fish 


June 1978 


3 


Oysters + 


1 Fish 


July 1978 


4 


Oysters 




September 1978 


4 


Oysters 




October 1978 


3 


Oysters + 


4 Fish 


November 1978 


3 


Oysters 




December 1978 


4 


Oysters + 


5 Fish 


January 1979 


1 


Oyster 




February 1979 


2 


Ovsters 




March 1979 


3 


Oysters 




TOTAL 


30 


+ 23 = 53 




Locations 








Various 









TABLE 21. ISTPM oyster sample summary. 



No. Date Sampling Location 



5 


5.4. 


1978 


71 


23.3. 


1978 


143 


24.5. 


1978 


176 


22.6. 


1978 


178 


20.6. 


1978 


184 


22.6. 


1978 


212 


20.7. 


1978 


223 


21.7. 


1978 


234 


18.7. 


1978 


242 


18.7. 


1978 


295 


20.9. 


1978 


297 


20.9. 


,1978 


311 


20.9. 


,1978 


327 


18.9, 


,1978 


349 


19.10. 


.1978 


357 


19.10, 


.1978 


359 


19.10, 


,1978 


399 


16.11. 


,1978 


400 


16.11, 


,1978 


406 


16.11, 


.1978 


420 


15.12, 


.1978 


436 


15.12, 


.1978 


440 


15.12, 


.1978 


442 


15.12. 


.1978 


446 


31.1, 


.1979 


471 


27.2, 


.1979 


473 


27.2. 


.1979 


514 


30.3, 


.1979 


517 


30.3, 


,1979 


518 


30.3, 


,1979 



Aber Benoit - Prat ar Coum 

Baie de L' Argue non 

Essai de decontamination 

Baie de Morlaix - Penze R.G. (Le Ven) 

Aber Benoit - Prat ar Coum 

Baie de Morlaix - Calot (transfert) 

Aber Benoit - Prat ar Coum 

Baie de Morlaix - Le Frout (Le Ven) 

Baie de Morlaix - Penze R G (Le Ven) 

Baie de Morlaix - Penze (B.I. Brannelec) 

Baie de Morlaix - Penze R D (Cablet) 

Baie de Morlaix - Penze R G (Le Ven) 

Baie de Morlaix - Penze R D (Gallion) 

Aber Benoit (Garo - Hanssen) 

Aber Benoit (Garo - Hanssen) 

Baie de Morlaix - Penze R D (Kerarmel) 

Baie de Morlaix - (B I Brannelec) 

Baie de Morlaix - Penze R D (V. Bernard) 

Baie de Morlaix - (B I Brannelec) 

Baie de Morlaix - Penze (Cadoret) 

Baie de Morlaix - Penze R G (Le Ven) 

Baie de Morlaix - Penze R D (Cadoret) 

Baie de Morlaix - Penze R G (Vallegant) 

Baie de Morlaix - R D lie Noire (Kerarmel) 

Baie de Morlaix - Penze R D (V. Bernard) 

Baie de Morlaix - Penze R D (Gallion) 

Baie de Morlaix - Penze R D (Vallegant) 

Baie de Morlaix - Penze R D (Cadoret) 

Baie de Morlaix - Penze R D (Ker Armel) 

Baie de Morlaix - Penze R D (Cadoret) 



90 



TABLE 22. ISTPM fish sample summary, 



No. 


Nature 


36-3 


lieu jaune 


40-7 


roussette 


41-3 


lieu noir 


58-1 


lieu jaune 


93-2 


mulet 


100 


flet 


118 


lieu jaune 


151 


maquereau 


170-1 


lieu jaune 


170-2 


lieu jaune 


198 


tacaud 


200 


lieu jaune 


203 


maquereau 


209 


mulet 


377-2 


plie 


379-3 


mulet 


415-2 


sole 


419-2 


grond in 


446-4 


plie 


449-2 


sole 


454-1 


plie 


454-6 


sole 


455-4 


plie 



Date Sampling Location 

13.04.1978 Portsall (3' H Amoco) 

13.04.1978 Roscoff (Bank ac Forest) 

13.04.1978 Portsall (8' N Amoco) 

13.04.1978 Portsall (2' E Amoco) 

27.04.1978 Portsall 

24.04.1978 Baie de Lannion 

29.04.1978 Portsall (3' £ Amoco) 

23.05.1978 Baie de Douarnenez 

11.05.1978 Riviere de Trequier 

11.05.1978 Riviere de Trequier 

16.05.1978 Baie de Lannion 

16.05.1978 Baie de Lannion 

3.05.1978 Baie de Lannion 

30.06.1978 Aber Wrac'h 

26.10.1978 lie de Batz 

24.10.1978 Baie de Morlaix 

6.12.1978 Baie de Lannion 

6.12.1978 Baie de Lannion 

15.10.1978 Baie de Morlaix 

15.10.1978 Baie de Morlaix 

5.12.1978 Aber Benoit 

5.12.1978 Aber Benoit 

20.12.1978 Aber Wrac'h 



TABLE 23. Results of ISTPM oyster analyses. 



Total Hydrocarbons 



Sample No. a 


(f, + 


£?; ug/g dry wt) 


5 




2700 


71 




610 


143 




180 


176 




530 


178* 




1600 


184 




380 


212 




270 


223 




400 


234 




640 


24 2 




80 


295 




340 


297 




270 


311 




290 


327 




630 


349 




420 


357 




320 


359 




50 


399 




100 


400 




95 


406 




70 


420 




150 


436* 




1000 


440 




90 


442 




150 


446* 




105 


471 




50 


473 




140 


514 




140 


517 




170 


518 




140 



Source 
(from GC) b 

1 

2/1 

2/3 

2 

2 

2 

2 

2/3 

2 

2/3 

2 

2 

2/3 

2 

2 

2 

2 

2 

2 

2 

2 

2 

3/2 

2/3 

3/2 

3/2 

2 

2 

2 

2 



GC/MS results available (Table 25). 



a See Table 21 for location and data of each sample number. 
b l = fresh AMOCO CADIZ oil 

2 = weathered oil 

3 = biogenic hydrocarbons 



91 



TABLE 24. Results of ISTPM fish analyses. 



Samp le N o. 

36-3 

40-7 

41-3 

58-1 

93-2 

LOO 

118 

151* 

170-1 

170-2* 

198 

200 

203 

209 

377-2 

379-3 

415-2 

419-2 

449-2 

454-1 

454-6 

455-4 



Tot.)L Hydrocarbons 

1 r _L * ( 2 : u '' 9 ,! . r X wt -' 

15 
39 
29 
18 
45 
70 
45 
170 
18 
31 
31 
69 
37 
30 

8 
25 
154 
15 
13 
21 
20 

6 



r Je 
(_f r_om GCJ ' 

3 

3 

3 

3 

2/3 

3/2 

3/2 

3/2 

3 

2 3 

3/2 

2/3 

3 

3 

3 

3 

3/2 

3 

3 

3 



* GC/MS results available (Table 25) . 



a See Table 22 for location and data of each sample number. 
b l • fresh AMOCO CADIZ oil 

2 ■ weathered oil 

3 » biogenic hydrocarbons 



TABLE 25. GC/MS results of selected analyses of oyster and fish tissues 
(ng/g) . 



Oysters 







1178 


1436 


1446 


1151 


1170-2 


N 




nd 


nd 


nd 


nd 


2 


C,N 




nd 


nd 


nd 


nd 


nd 


C ? N 




nd 


nd 


nd 


nd 


nd 


C,N 




290 


nd 


52 


nd 


nd 


C 4 N 




1400 


nd 


150 


nd 


nd 


N 




2190 


nd 


202 


nd 


2 


P 




220 


30 


85 


17 


40 


ClP 




1400 


nd 


220 


30 


70 


C ? P 




4600 


130 


350 


30 


60 


C,P 




9500 


200 


1300 


20 


50 


C 4 P 




10000 


100 


1300 


10 


40 


p 




25720 


460 


3170 


107 


260 


DBT 




180 


nd 


16 


nd 


2 


C 1 DBT 


1400 


nd 


100 


nd 


24 


C 2 DBT 


6400 


320 


480 


nd 


120 


C3DBT 


9600 


580 


1410 


nd 


100 


DBT 




17580 


900 


2006 


nd 


246 


m/e 


202 


700 


100 


320 


30 


41 


m/e 


228 


900 


30 


330 


nd 


20 


m/e 


252 


500 


nd 


400 


nd 


nd 



N ■ naphthalenes 

P - phenanthrenes 

DBT - dibenzothiophenes 

202 ■ fluocanthene + pyrene 

228 =• benzanthracene ♦ chrysene 

25 2 - benzof luoranthenes + benzopyrenes 



92 



TABLE 26. Petroleum hydrocarbons in oysters. 



LOCATION 



DATE 



Z PETROLEUM 
(ppm) 



Aber Benoit 



Baie de Morlaix 



April 5, 1978 


2,700 


June 20, 1978 


1,600 


July 20, 1978 


270 


September 18, 1978 


620 


September 19, 1978 


410 


June 2, 1978 


530 


July 1978 


70-600 


October 19, 1978 


60-230 


February 27, 1979 


240 


March 30, 1979 


150 





FIGURE 3.80. Baie de Morlaix impacted oysters - aromatic hydrocarbons; 
A - 5 April 1978; B - 27 February 1979. 

93 



3.7 Seaweed and Sediments (Topinka, Bigelow Laboratory for Ocean 
Sciences) 

In support of an investigation on the impact of the spill on 
macroalgal population recovery and growth, a series of plant and 
adjacent sediment samples was analyzed by GC to determine if and to 
what extent AMOCO oil was associated with the plants (Table 27). 

The data presented in Table 28 in conjunction with a consideration 
of Figures 3.81 and 3.82 illustrate that while several of the plant 
samples do contain weathered oil (see Fig. 3.81) the n-alkane, penta- 
decane (n-C^) , is the most abundant biogenic component in all sam- 
ples. The distribution of biogenic components in general (Fig. 3.82) 
can be seen as contributing markedly to the total hydrocarbon levels 
even in the "oil-impacted" tissues. 

GC/MS results of an "oil impacted" plant's aromatic hydrocarbon 
fraction (Table 29) indicate that again the P and DBT family series are 
the most abundant aromatic compounds present. In this sample the P 
compounds are, in total, more abundant than the DBT series, but the 
C3DBT are still the most abundant group (8400 ppb) . 



TABLE 27. AMOCO CADIZ chemistry program; seaweed samples (Topinka). 



Frequency 

June 1979 15 Plant + 7 Sediment 
August 1979 2 Plant 
May 1980 3 Plant 

Summer 1980 12 Plant 



TOTAL 32 

Locations 
Var ious 

GC/MS 

One Seaweed Sample 



94 



TABLE 28. Summary of analytical results; seaweeds, summer 1980. 



Gravimetr ic 



Sample t x (pg/g) f 2 (ug/g) 



HC-4-1 


41 


HC-4-2 


10 


HC-4-3 


11 


HC-5-1 


31 


HC-5-2 


61 


HC-5-3 


61 


HC-5-4 


11 


HC-5-5 


39 


HC-5-6 


17 


HC-5-7 


10 


HC-5-8 


12 


HC-5-8 


8 


(Repeat) 





HC-5-9 



74 
16 
14 
29 
72 
52 
12 
23 
16 
7 
9 
12 

15 



GC 



n_c 15 (P9/9) Status 



38.5 
10.7 

4.8 

5.0 
35.0 
25.0 
21.3 
58.0 
25.3 

7.2 
34.0 

9.0 

3.7 



1/2 

2 

2 

1/2 

1/2 

1/2 

2 

2 

2 

2 

2 

2 



Status codes: 1 = weathered petroleum 
2 = biogenic 



TABLE 29. GC/MS results of seaweed aromatic fraction analysis (sample 
HC-5; Tregolonou, Fucus vesiculosis ; 4 June 1979) . 



Compound 

Cj-f luorene 
Phenanthrene (P) 
CjP 

c 2 p 

C 3 P 
C 4 P 

ip 

Dibenzothiophene (DBT) 
C^BT 
C 2 DBT 
C3DBT 

I DBT 

m/e 202 ( f luoranthene + pyrene) 
m/e 252 (benzof luoranthenes 
+ benzopyrenes) 



Concentration 
(ng/dry weight plant) 

610 

420 
. 920 
2400 
6400 
5300 
15,440 

40 

300 

4000 

8400 

12,740 

930 
1800 



95 






p 



w 



ma. 



\i 



SATlJHA t tS 




FIGURE 3.81. HC-4-1 seaweed hydrocarbons - oil-impacted. 



IWU.i 







1 


1 


III 




i 








1 

1 

1 


\ 




i 




.III 


w 


1 


, \ 


i 


i. 



j; 



l *lU I 



SAf UHArtb 



'I l! 



Jjiiil'Ailni LJi 



ill 



Ml J J 



«ttl' 



A.U.I. 



, Ij 



(WjJ, 



.1^ -I I 



U AHIjMA I l( ^ 



FIGURE 3.82. Seaweed hydrocarbons control. 



96 



CONCLUSIONS 

A number of specific conclusions concerning the levels of AMOCO 
CADIZ petroleum hydrocarbons in various environmental compartments, the 
changing chemistry of the hydrocarbon assemblages, and the persistence 
of petroleum in these compartments are presented here. 

1) Upon introduction into the environment, the oil weathered 
rapidly with evaporation and biodegradation changing the oil's 
chemistry markedly even prior to landfall. 

2) Oil impacted a variety of intertidal sedimentary types and a 
number of secondary impacts were noted at many stations. 

3) Oil was buried in most sedimentary environments with burial 
and/or penetration down to 15 cm in fine-grained sediments and 
deeper (^20-30 cm) in sandy sediment. 

4) Oil remained less biodegraded in sandy beach environments than 
in fine-grained sediments in which heavily biodegraded oil was 
characteristic. 

5) The presence of UCM material, pentacyclic triterpanes, and 
alkylated phenanthrene and dibenzothiophene compounds remain 
as characteristic chemical features of AMOCO CADIZ oil in 
sediments. 

6) Less weathered oil appeared to be buried (10-20 cm) in fine- 
grained sediments as evidenced in samples taken one year after 
the spill. 

7) Offshore sediments were impacted after the shoreline impact, 
probably through processes involving beaching, sorption on 
intertidal sediments, and offshore transport of these sedi- 
ments. Samples taken after the spill in April 1978 do not 
reveal AMOCO CADIZ oil, thus indicating a lag (weeks to 
months) in offshore deposition. 

8) Surface intertidal sediments taken in June 1981 show that 
"normal" background inputs, both of biogenic and chronic 
pollutant origins, have replaced AMOCO CADIZ oil as major 
components of the hydrocarbon geochemistry. Only at the most 
impacted stations at lie Grande marsh and within the sandy 
beach sediment at AMC-4 (Portsall) do identifiable AMOCO 
residues persist. At lie Grande the aromatic marker compounds 
are absent, but hopanoid compounds (triterpanes) and a large 
UCM persist. 



97 



9) Oysters were initially heavily impacted by oil (several 
thousand ppm) and after two years (June 1980) traceable 
AMOCO CADIZ residues are still evidenced by homologous series 
of isoprenoid alkanes, phenanthrenes and dibenzothiophenes. 
Petroleum residues persist approximately at the 100 ppm 
level . 

10) Fish do not appear to have been directly impacted (chemical- 
ly) by the spillage to any significant extent. 

11) Compositional profiles traceable to AMOCO CADIZ oil are likely 
to "disappear" from all sediments within another year (i.e. 
1982; four years after the spill) although this should be 
confirmed by direct measurements and attention to molecular 
marker compound distributions. 

REFERENCES 

Atlas, R. M. , P. D. Boehm, and J. A. Calder, 1981, Chemical and biolog- 
ical weathering of oil from the AMOCO CADIZ oil spillage, within 
the littoral zone: Estuarine Coastal Mar. Sci., Vol. 12, pp. 589- 
608. 

Blumer M., M. Ehrhardt, and J. H. Jones, 1973, The environmental fate of 
stranded crude oil: Deep Sea Res., Vol. 20, pp. 239-259. 

Boehm, P. D., 1980, Gulf and Atlantic Survey (Gas I): Atlantic survey 
for selected pollutants: Final Report, NOAA/NMFS Contract NA-90- 
FA-C-00046, National Marine Fisheries Service, Sandy Hook, New 
Jersey. 

Boehm, P. D. and P. Hirtzer, 1981, Gulf and Atlantic survey (GASI) Ches- 
apeake Bay to Port Isabel, Texas: survey for selected organic 
pollutants in finfish: Draft Final Report, NOAA/NMFS, Sandy Hook, 
New Jersey. 

Boehm, P. D. , D. L. Fiest, and A. A. Elskus, 1981, Comparative weather- 
ing patterns of hydrocarbons from the AMOCO CADIZ oil spill 
observed at a variety of coastal environments: Jji AMOCO CADIZ - 
Fates and Effects of the Oil Spill, Proceedings of the Interna- 
tional Symposium, 19-22 November 1979, pp. 159-173. 

Boehm, P. D. , J. E. Barak, D. L. Fiest, and A. A. Elskus, 1982, A chem- 
ical investigation of the transport and fate of petroleum hydrocar- 
bons in littoral and benthic environments: the TSESIS oil spill: 
Marine Environ. Res., (in press). 

Brown, D. W. , L. S. Ramos, M. Y. Uyeda, A. J. Friedman, and W. D. Mac- 
Leod, Jr., 1980, Ambient temperature contamination of hydrocarbons 
from marine sediment - comparison with boiling solvent extractions: 
in L. Petrakis and F. T. Weiss (Eds.), Petroleum in the Marine 
Environment, Advances in Chemistry Series No. 185, American Chem- 
ical Society, Washington, D.C., pp. 313-326. 

98 



Calder, J. A. and P. D. Boehm, 1981, The chemistry of AMOCO CADIZ oil in 
the L'Aber Wrac'h: jji AMOCO CADIZ: Fates and Effects of the Oil 
Spill, Proceedings of the International Symposium, 19-22 November 
1979, Brest, France, pp. 149-178. 

Dastillung, M. and P. Albrecht, 1976, Molecular test for oil pollution 
in surface sediments: Mar. Poll. Bull., Vol. 7, pp. 13-15. 

Grahl-Nielsen, O. , J. T. Staveland, S. Wilhelmsen, 1978, Aromatic hydro- 
carbons in benthic organisms from coastal areas polluted by Iranian 
crude oil: J. Fish. Res. Bd. Canada, Vol. 35, pp. 615-623. 

Gundlach, E. R. and M. 0. Hayes, 1978, Investigations of beach pro- 
cesses: _in The AMOCO CADIZ Oil Spill, A Preliminary Scientific 
Report, NOAA/EPA Special Report, Washington, D.C., pp. 85-197. 

Mayo, D. W. , D. S. Page, J. Cooley, E. Sorenson, F. Bradlev, E. S. Gil- 
fillan, and S. A. Hanson, 1978, Weathering characteristics of 
petroleum hydrocarbons deposited in fine clay marine sediments, 
Searsport, Maine: J. Fish. Res. Bd. Canada, Vol. 35, pp. 552-562. 

Neff, J. M. , B. A. Cox, D. Dixit, and J. W. Anderson, 1976, Accumulation 
and release of petroleum derived aromatic hydrocarbons by four spe- 
cies of marine animals: Mar. Biol., Vol. 38, pp. 279-289. 

Overton, E. B. , J. McFall, S. W. Mascarella, C. F. Steele, S. A. An- 
toine, I. R. Politzer, and J. L. Laseter, 1981, Petroleum residue 
source identification after a fire and oil spill: jji Proceedings 
1981 Oil Spill Conference, American Petroleum Institute, Washing- 
ton, D.C., pp. 541-546. 

Pym, J. G., J. E. Ray, G. W. Smith, and E. V. Whitehead, 1975, Petroleum 
triterpane fingerprinting of crude oils: Anal. Chem., Vol. 47, pp. 
1617-1622. 

Rashid, M. A., 1974, Degradation of bunker C oil under different coastal 
environments of Chedabucto Bay, Nova Scotia: Estuarine Coastal 
Mar. Sci., Vol. 2, pp. 137-144. 

Roesijadi, G. , D. L. Woodruff, and J. W. Anderson, 1978, Bioavailability 
of naphthalenes from marine sediments artificially contaminated 
with Prudhoe Bay crude oil: Environ. Pollut., Vol. 15, pp. 
223-229. 

Teal, J. M., K. Burns, and J. Farrington, 1978, Analyses of aromatic 
hydrocarbons in intertidal sediment resulting from two spills of 
No. 2 fuel oil in Buzzards Bay, MA: J. Fish. Res. Canada, Vol. 35, 
pp. 510-520. 

Warner, J. S., 1976, Determination of aliphatic and aromatic hydrocar- 
bons in marine organisms: Anal. Chem., Vol. 48, pp. 578-583. 

Winfrey, M. R. , E. Beck, P. Boehm, D. Ward, 1981, Impact of the AMOCO 
CADIZ oil spill on sulfate reduction and methane production in 
French intertidal sediments: Mar. Environ. Res., (submitted). 

99 



STUDIES OF HYDROCARBON CONCENTRATIONS AT THE ILE 
GRANDE AND BAIE DE LANNION STATIONS POLLUTED 
BY THE WRECK OF THE AMOCO CADIZ 

Henri Dou, Gerard Giusti, and Gilbert Mille 

Laboratoire de Chimie Organique A, Associe au CNRS 
n°126, Centre de St. Jerome 
13397 Marseilles Cedex 13, France 



INTRODUCTION 

A study of the hydrocarbon concentrations in district no. 7 has been made 
since December 1978 in collaboration with the Marine Station of Endoume (Mes- 
dames Vacelet, Plante, and Lecampion) . The first series of analyses was made 
outside of the CNEXO-NOAA framework, while our second study was supported by 
them. Results of the two studies are herein combined. 



METHODS 
Nature of the Samples 

Samples were collected at sites indicated in Figure 1. Sample sites A, 
D, and F are located in a very polluted zone; B, C, and E are located in a 
zone where the pollution level is lower since a dam was erected under the 
bridge to prevent the spreading of oil. Subscripts indicate specific areas 
samples: 1 - marsh, 1 = tidal creek, and 3 = upper mud flat (see Figs. 1 and 
2). 

Samples were collected in December 1978, March 1979, November 1979, and 
May 1980, using a plexiglass corer (ID = 26 mm). The 5 mm superficial layer 
was subsampled with a steel spatula. Sediments were immediately frozen, flown 
to Marseilles, and kept at -30 C. 



Analytical Techniques 

To yield the maximum amount of information, we have chosen the systematic 
soxhlet extraction following Farrington's method. This method is expensive 
and time-consuming but, for the biologists, it is the only one which gives 
satisfactory results. Moreover, reproducibility was tested several times and 
was found to be satisfactory. 

To avoid the very long separation of alumina- or silica-packed columns, 
we developed a micromethod of separation using Sep-Pak of Waters. This rapid 
technique is described in Analytica Chemica Acta. The general analytical 
scheme is as follows: 



101 




pn SOIL Od 

1 "*l scMOHne: 

AI,DI,CI,BI 

□ MUD ON 
SANDY MUD 

AI£2,A3,B3,E3 



SAMPLING SITES 
REFERENCE STATIONS -CI, Bl SCHORRE(SALT MARSH) 
C2 TIDAL CREEK 

POLLUTED STATIONS « AI.DI SCHORRE(SALT MARSH ) 
A2 TIDAL CREEK 
A3 SLIKKE(MUD SLOPE) 



FIGURE 1. lie Grande marsh sampling sites. 



M W- 




CHENAL 
tidal creek 



UHAUTE-SLIKKE — 
higher mud slope 



SCHORRE - 
solt meadow 



FIGURE 2. Detailed map of the sampling area. 



102 



sample 



1 - extraction (toluene methanol-soxhlet) 

2 - pentane, water + sodium chlorida 



weight before saponification 
AVSP 



saponification with KOH 



weight after saponification 
APSP 



separation with SEP PAK 



hexane elution 




chloroform elution 



fraction hydrocarbons. 
FA 



polar fraction 
FB 



Each fraction was weighted by gravimetry (Balance: Perkin Elmer AD2Z, 1/10 of 
ug) . In each case, the fraction FA was chroma tog raphed on a capillary column 
(OV1 or SE52) with a Girdel or a Carlo Erba Fractovap 4160. The fractions FA 
and FB were also analyzed by high-pressure liquid chromatograph (column RP 18, 
radial pressure, Waters-type detector). Since the FA fraction may contain 
saturated, unsaturated, or aromatic hydrocarbons, fluorescence spectrometry 
(Perkin Elmer 3000) was used especially during the 1980 survey when 
biodegradation rates were higher. Infrared spectroscopy (Perkin Elmer 125 and 
225) was also used systematically to show the absence of carbonyl functions on 
the FA fractions. .During the 1980 campaign, it appeared that some of the 
chromatograms of the FA fractions were not sufficiently resolved due to the 
absence of saturated hydrocarbons. However, as they represented a substantial 
weight (A. * 257 g; A, ■ 14 g) , NMR spectroscopy (C 13 and proton 250 Mz 
Cameca) was used to denote the presence of heavy-weight compounds with fused 



103 



rings (aromatic and nonaromatic) . The structure of these complex mixtures was 
not elucidated at this time, but could be studied in the future. 



RESULTS 

Results are presented in Tables 1, 2, and 3. The weight of the compounds 
AVSP (before saponification) and APSP (after saponification) are indicated. 
The value of the ratio AVSP/APSP is characteristic of the capacity of the 
medium to be biodegraded. A value close to 1 shows poor bacterial activity. 
As the value increases, better biodegradation is indicated. This fact is due 
to the functionalized intermediate compounds made by the bacteria and extract 
in basic medium. 

The fraction FB is constituted by unsaponif iable compounds. Comparison 
of FA and FB is not interesting. Only the comparison of FB values for 
different sampling times is relevant. When biodegradation increases (less 
linear hydrocarbons) , the FB fraction decreases. At Al and A2 station (in 
very polluted zones) , the concentrations of hydrocarbons (linear or 
substituted) were about null in 1980, but complex organic compounds of heavy 
molecular weight, which are extractable with hexane (since present in the FA 
fraction) , remain in the sediment. The molecular structure of these compounds 
has not been established (the pet role urn- type asphaltenes are not extracted at 
the very beginning by pentane) . 



CONCLUSIONS 

Station C. 

In 1980, in spite of the presence of 0.54 g in the FA fraction, its 
chromatogram was no longer characteristic of a petroleum-polluted zone (C17, 
C18, C19 predominant). However, light petroleum pollution is indicated at 20 
cm below the surface. 



Station B_ 

In 1980, various deposits did not allow correct sampling; therefore, only 
1978 and 1979 values were determined. In 1979, there seemed to an indication 
of return to normal state, especially at the rhizome level (bottom) . 



Station A. 

In 1980, half of the hydrocarbons of 1979 remained. This fraction did 
not show the presence (by chromatogram) of linear or substituted hydrocarbons; 
however, its weight cannot be explained only by the unbiodegradable cyclanes 
or aromatics (33 g) . 



104 



TABLE 1. Hydrocarbon content of lie Grande marsh sediments. 



SAMPLE WET AV-SP 

WEIGHT (q) <q/kq) 









TOTAL 


AP-SP 




FB 


HYDROCARBONS 


(q/kql 


AV/AP 


<q/kq) 


(FA) (q, kql 


1 '.1/79 


12/78 11/79 


12/78 11/79 


12/78 11,7 



W 11 
59.15 
24.23 


14.60 
90. 10 
74. 60 


17 3.90 

19. 76 

1.69 


243 45 
1.96 
0. 24 


162 

16 

1 


50 
50 
46 


210.50 
0.96 
0.19 


13. JO 
SI. SO 


10.63 
97.60 


6.00 
2.12 


10.29 
1. 99 


5 
1 


15 
30 


6 56 

0. 69 


15. 15 

56.50 


19.65 
1)2.50 


1 1.74 
2.41 


2.41 
0.15 


12 
1 


.27 
,59 


1.91 

0. 12 



^lrth Channel 



51. 20 


6.10 


16.52 


21. 49 


16.70 


63.50 


120.60 


1.79 


0.93 


1.42 


23. 10 


139. 20 


'0.62 


0.17 


0. 11 


10.50 


15.90 


14.07 


6. 32 


6.27 


39. 60 


41. 20 


3.07 


1.69 


2.26 


18.65 


76.90 


0.60 


0.92 


0.4S 



1.07 1.15 67.90 

1.20 2.06 6.40 

1.26 1.26 1.00 

1.34 1.14 4.00 

1.63 2. 24 t . 06 

1.12 1. 26 8. 10 

1.52 1.25 1.3] 



9. 00 
0.91 

0. 21 

5.00 
1.50 



1 


11 


1 


.'5 


2 


.03 


, 


.70 


1 


.26 


1 


.33 



12. 


97 


18 


A4 


0, 


47 


3. 


68 


<M 


68 


94 


SI 


1 


1 ) 


0, 


2 } 





48 


0, 


10 


1 


90 


1, 


75 





. 1 7 





10 


4 


17 


0. 


43 





. 26 





03 



6. 


59 





29 


0. 


J 


1. 


41 


0, 


09 



I'pper *ud Flat 



1.05 11.48 16.91 11.44 12. 91 1.00 1. 31 5. 88 8. 

106.50 7.43 6.66 1.12 3.54 

7.50 6.11 2.66 2. 32 1. 14 

112.30 3.43 1.76 1.95 1.14 



Arabian light 100 q 



AV-SP • Before eeponif ica tlon AV/AP - Ratio 

Kp-SP - After saponi t lcation FB ■ Fraction B separated by Sep-Pak, HC CI elution 

weight in q per kg of dry sediisent. FB • Fraction A, hexane elution; total hydrocarbon* 

"T^ese concentrations were eva iu- ps • Surface crust 



j ted from sediment sample* scraped 
by a spatula to about 0.05 en depth. 



105 



TABLE 2. Hydrocarbon concentrations with depth. 



BIOTOPE AND 
STATIONS 



DEPTH OF 
SAMPLE (cm) 



TOTAL HC; g/kg OF DRY SEDIMENT 
12/78 3/79 11/79 5/80 



Marsh 



Di 



Bi 



Ci 



ps 
0- 3 
3-14 

34-37 

0- 3 

3-14 

14-26 

0- 3 
3-14 

ps 
0- 3 
3-14 

14-32 



32. 


97 


0. 


47 


94. 


68 


8. 


13 


0. 


48 


1. 


90 


o. 


17 


4. 


17 


0, 


.26 



IB. 


84 


3. 


68 


94. 


51 


0. 


23 


0. 


10 


1. 


75 


0. 


10 


0. 


43 


0. 


03 



39.87 
14.98 

0.03 
0.04 

230.60 

17.78 
0.18 



1.50 
0. 54 
0. 15 
0. 05 



Channel 



A 2 



0- 


3 


3- 


9 


9- 


28 


28- 


36 


ps 




0- 


3 


3- 


9 


9- 


28 











14. 20 


7.69 


10. 


78 


6. 59 


2. 57 


0. 48 


0. 


22 


0. 29 


1. 14 


0- 10 






0.03 


0. 08 
0.08 

0.07 


3- 26 






1. 41 




0. 77 
0- 23 






0. 09 
0. 05 





Upper Mud Flat 



Ej 



B, 



0- 
3- 



5. 5(, 



0- 3 

3-1 1 

1 1-20 

20-27 

ps 
0- 3 
3-15 

15-19 



24. 95 
0. 65 



3. 45 
2. 40 



0. 52 
0. 19 



0.27- 


■15 


0. 


60 


0. 


50 


0. 


89 


0. 


08 


0. 


08 


2. 


81 


0. 


56 


0. 


22 


0. 


16 



ps = surface crust, sampled by scraping 



106 



TABLE 3. Chromatographic analysis of the saturated fraction of hydrocarbons 
from He Grande sediments. 



STATIONS 



'I7/Pr 



12/78 



'I8/Ph 



Pr/Ph 



Predominance x 



11/79 12/78 11/79 12/78 11/79 12/78 11/79 



Marsh 



Ai 


su 


1. 


0.5 


0.77 


0. 58 


0.54 


0.67 


1. 


XX 




rh 


0.48 


0.5 


0.41 


0. 21 


0. 61 


0.35 


1. 


XX 


Di 


su 


0.60 


0.2 


0.47 


0.11 


0.60 


0.54 


1. 


XX 




rh 


1.24 


1. 5 


0.93 


1.92 


0.75 


0.66 


1. 


1.40 




ca 


3.30 


2. 


0.78 


1.92 


0. 17 


0.83 


XX 


XX - 


Bi 


su 


XX 


4.43 


XX 


2.62 


XX 


0.54 


XX 


1.57 




rh 


0.21 


1. 31 


1.75 


4. 


7.80 


3.2 


2.37 


XX 


Ci 


su 




1.42 




6. 20 




3.80 




1.11 




rh 




2.80 




6.67 




1.66 




1.05 



Marsh Channel 



A 2 



C 2 



A 3 



B 3 



ps 




0.35 




0.13 




0.56 




XX 


zr 




0.50 




0.26 




0. 58 




1.25 


ca 




1.00 




3. 50 




2. 20 




1.03 


su 


0.13 


0. 19 


0. 39 


0. 44 


3.50 


23.33 


0.99 


1.84 


zr 


0.13 


1.25 


0.26 


2. 5 


2. 28 


4. 


1.06 


1.48 


cs 


2.33 


3.33 


5.30 


3.5 


2. 


0.75 


0.89 


1.30 


ps 




4.10 




6.00 




1.25 




1.03 


cs 




0.09 




■ 0.06 




<-0.85 




XX 


ps 




0.53 




0.53 




0.94 




1.04 


cs 




0.29 




0.14 




4.72 




1.60 



Arabian light 10.30 



4.70 



0.48 



0.88 



x predominance = 



2<C 23 + C 25 * C 27> 
C 22 + 2C 24 +2C 26 + C 28 



aliphatic hydrocarhons 



xx = Nonextractable 

su = Superficial part; some centimeters 

rh = Rhizosphere 

cs = Sandy layer 



Pr = Pristane 
Ph = Phytane 
zr = Reduced zone 
ca = Clay layer 



107 



Station D, 

This site is subjected to a flowing stream which must have facilitated 
the deposit of hydrocarbons in large quantity, since between 1978 and 1980, an 
important increase was measured (95 g in 1978 to 230 g in 1980) . 



Station C« 

This site indicates that substantial biodegradation is in progress. 



Station A, 

In the FA fraction, we again notice the presence of organic compounds 
which are neither linear nor substituted. The ratio FA 1978/FA 1980 is very 
close to that of station Al. 



Stations B and E 

These are reference stations in the less polluted zone. Some remaining 
pollution is visible, indicating that the dam was not able to prevent oil from 
spreading to this side of the bridge. In 1980 at B_, the chromatogram of the 
FA fraction did not indicate petroleum type, and there was a return to normal 
levels. At E. in 1980, some minor petroleum pollution remained. 



Station A 3 

There are large variations in the hydrocarbon concentrations, primarily 
at the sediment surface. Two separate samplings in 1980 (5 mm depth) yielded 
0.27 g and 15 g of oil. However, at -10 cm, the values became equal to 0.50 
g. The analysis of the 15-g fraction shows that linear and substituted 
hydrocarbons have disappeared. 



Our results are in good agreement with those noted by biologists. The 
less polluted zones are returning to a normal state, but a seemingly important 
residue remains in very polluted sites after linear, substituted, and light 
aromatic hydrocarbons have disappeared. 



108 



1A 



_jiU' 



Pr 
i 







IB 



•JlIw 




2A 



2B 



P* 



1 r - 






y ' 




izJj^^'- 




'3 



L 



L 



_> 





U4JjJUuUJ^^~^_ 



Chromatogram 1) Station A 3 , March 1979. (A) surface, (B) bottom. 

2) Station A 2 , March 1979. (A) surface, (B) bottom. 

3) Station A3, 1980, surface skim. 

4) Station D, 1980, 0-3 cm surface. 



109 



EVOLUTION OF THE HYDROCARBONS PRESENT IN 
THE SEDIMENTS OF THE ABER WRAC ' H ESTUARY 

by 
Jean DUCREUX 

Institut Francais du Petrole 
92506 Rueil-Malmaison - FRANCE 



Following the Amoco Cadiz accident, the Institut Francais du 
Petrole analyzed various samples in an effort to learn the physico- 
chemical characteristics of the oil pollutant released, and to observe 
its evolution over time. These studies dealt principally with samples 
of "chocolate mousse" and of beach-sand type surface sediments taken 
at various depths. 

In March 1978 a study of the physico-chemical evolution of the 
hydrocarbons trapped in the subtidal sediments of the Aber Wrac'h 
estuary was undertaken with the collaboration of the Centre Oceanolo- 
gique de Bretagne. 

INITIAL CHARACTERIZATION OF THE POLLUTANT 

The description of the Amoco Cadiz 's cargo was undertaken on the 
basis of samples of foam ("chocolate mousse") taken at Portsall on 
March 22 and 23, 1981. This method of identification is based on the 
work of Pelet and Castex, and operates according to a breakdown by 
chemical family, which has already been used by J. Roucache to make 
a geochemical study of the organic matter extracted from sediments. 

The pollutant was identified as a mixture of two crude oils 
— Iranian light and Arabian light — physico-chemical characteristics 
of which are fairly similar ; they contain 45 to 47 % saturated hydro- 
carbons, 31 to 34 % aromatic hydrocarbons, 16 to 17 % polar compounds, 
and 4 to 5 % asphalt compounds (Fig. 1). The ratio of saturated hydro- 
carbons to aromatic hydrocarbons is on the order of 1.3. 

The saturated fraction is constituted of normal paraffins, iso- 
paraffins of isoprenoid compounds (pristane, phytane, etc..) and 
cyclic and polycyclic alkanes or cycloparaf fins . With gas-phase 
chromatography, n-alkanes in the sample taken at Portsall 23 March 
follow a regular distribution curve ; her top corresponds to the 
n-Cl5 and n-Cl6, after which it tapers off regularly to the n-C35 
(Fig. 1). It is likely, incidentally, that compounds over n-C35 exist, 
but they have not yet been detected. 

Ratios of pristanes/n-C17 and phytanes/n-C18 in crude oil are, 
respectively, 0.37 and 0.51. To take into account evaporation pheno- 
mena and compare with evolved samples, this oil sample was topped at 
340°C. 

An unresolved complex mixture (UCM) appears under the n-alkanes, 
constituted of isoparaffins and cycloparaf fins. Alkane (n+iso) 

111 






- f 2104 "*. vli . ! i » ■ 



-JOJ34 *'. W«Iilf •— 



-Iai3i *ilnmt i- 






c 

10 

•H 

a 
< 
c 

(0 






I 



CD 



o 

0. 




_^ 




-^. 




< 




% 




< 


r " 


=r 

^ 




5 


N 


i 




1 

? 






c 

IT) 

•rH 

C 
(0 



00 



O 






U) 

•U 
Vl 



0< 



(/) 

c 
o 

u 

U 

o 

n 
>, 

r. 

<U 
■U 
<TJ 

3 
JJ 
nl 
CO 



o 
o 






•31 



.>r 






112 



contents determined by mass spectrometry are on the order of 5 3 %. 
Cyclane contents decrease gradually from 14.2 % for the single- 
membered cycloparaf fin rings, to 2.3 % for six-membered rings. 

The combination of gas-phase chromatography with mass spectro- 
metry (GPC/MS) made it possible to distinguish the components of the 
aromatic fraction : monoaromatic, diaromatic, and triaromatic hydro- 
carbons . 

Aromatic sulfur compounds of the thiophenic type are the benzo- 
thiophenes, dibenzothiophenes, and naphthobenzothiophenes. 

Polar compounds (resins) contain oxygenated functions (princi- 
pally hydroxyls and carboxyls) shown by infra-red spectrometer ana- 
lysis. Elemental analysis of this resin fraction made it possible to 
assess contents of the following elements : 

C = 78 % 

H = 8.9 % 

N = 1.5 % 

= 4.5 % 

In this case, the oxygen content is not calculated by subtracting 
the total of the other contents from 100 %, but is titrated by the 
Unterzaucher method. 

Asphaltene compounds, separated from the oil by cold-hexane 
precipitation, are known to have very complex laminated structures. 

Metal (such as nickel and vanadium) and sulfur contents were 
determined on a dry extract before deasphalting (Fig. 2). Metals are 
essentially present in heavy fractions of crude (resins and asphal- 
tenes) as chelate compounds. Their contents range from 14 to 16.5 ppm 
for nickel and from 45 to 60 ppm for vanadium, with a ratio Ni/V of 
0.27 to 0.31. Sulfur contents are on the order of 2.35 % by weight. 

These determinations will eventually serve as a point of depar- 
ture in following the pathways of the pollutant. It is to be noted 
that this study is not intended to cover the light evaporated and/or 
dissolved third of the cargo, of which about 25,000 tons is light 
aromatic hydrocarbons. Benzene, toluene, and xylene are estimated at 
respectively 3,300, 4,600, and 3,000 tons. 

EVOLUTION OF THE PHYSICO-CHEMICAL PARAMETERS OF THE HYDROCARBONS 

We followed the chemical evolution of the hydrocarbons in three 
different types of samples taken from three areas of pollution : 

- subtidal sediments (Aber Wrac'h) ; 

- water surface-stable emulsions (hydrocarbons with water, or "choco- 
late mousse") ; 

- intertidal sediments (beaches) . 

The Subtidal Sediments of the Aber Wrac'h 

A detailed study of these sediments was made by DUCREUX and 
MARCHAND (1979) (collaboration IFP/COB) . The evolution of the 

113 



[HiLJJL r ..\l] 



L V r ii ! L 1 S A T I 



EXTRACTION /CI! CI , 



U-pMi 



ENLEVEMENT D U S LIBRE 



I 
1 R 
ITf.cur c. KZ ict-uz/ 



A IB A 



extrait se: 



(Teneur cr. .V" trzcuz/ 



D E S A S P H V L T A C 



EXTRAIT DES'SRH^LT: 



C C "I 



HC. SATURES 



S M 



C C 



HC. AROMATIQl'ES 



C G 



RE SINES 



I R 



FIGURE 2. The program of analysis. 

hydrocarbons trapped in the subtidal sediments of the Aber Wrac'h was 
followed from March 31, 1978 to October 22, 1979 at nine stations 
(Fig. 3) in the estuary, taking into account the fairly pronounced 
marine character of the environment and the sandy, muddy, or sandy/ 
muddy nature of the sediments. 

Over a second period, from January 17, 1980 to June 24, 1980, 
three study sites, Stations 5, 6 and 8, which were deemed representa- 
tive of the different evolutionary patterns of the hydrocarbons, were 
again put into operation. The studies undertaken at these three 
stations only, are included in this report. To simplify the evolutions 
observed in the Aber Wrac'h, the figures included here are limited to 
samplings taken on March 31, 1978, November 22, 1978, June 20, 1979, 
January 17, 1980, and June 24, 1980. 

Station 5 

A reduction was noted in the pollution of this station, situated 
in the outer area of the Aber where the marine environment is parti- 
cularly pronounced (Fig. 4). It was very slight, however, since the 
concentrations observed in June 1980 were over 670 mg of hydrocarbons 
per kilogram of sediment. This may be explained by the slightly muddy 
character of the sediment. 



114 



Aaen wrac'h 




• Plougu£rnaao 



# LAnnili« 



1690 — 



mg.HC/kgSEO 



1000_ 



100. 



3t 03 7B 



FIGURE 3. The Aber Wrac'h. 




7T 



20 06-79 



17-oS-BO JToV 



■SO 



FIGURE 4. Evolution of hydrocarbon contents in the sediments 
of the Aber Wrac'h. 



115 



The relative contents of saturated and aromatic hydrocarbons 
decreased perceptibly (Fig. 5) in nearly constant proportions, the 
ratio SAT/ARO decreased slightly probably because of a significant 
increase in resins -- from 17 to 40 % by weight. After January 1980, 
however, contents of all these substance remained about the same. 



4 



40. 


y 




* ' 


= 7'Sl! 71 3 


30. 








Jk STS 


20. 








— • SIS 
"~* SI8 


in 














i i 


i 


1 



AW 31-3-71 



%AR0 



AW 22 II 78 



AW ?C E 7S 



AW 17 1-80 



AW 24-6-80 




FIGURE 5. Evolution of the various chemical families (saturated 
hydrocarbons, aromatic hydrocarbons, polar compounds). 



The increase in resin contents results from an oxidation degra- 
dation of the crude in the medium, reflected in a perceptible upward 
curve of the absorption bands under infra-red at the level of the 
hydroxyls (3,600 to 2,900 cm" 1 ) and the carbonyls — including 
esters, and a qreat predominance of Carboxylic acids (1,740 -> 

116 



1,700 cm -1 ; (Figure 6). The elemental analyses of 

the resins confirm this tendency toward oxidation over time (oxygen 

levels in March 1978 were 5.4 % ; in June 1980, 7 %). 




31 03-78 



22-11-78 



20 06-79 



17-01-80 



24-06-80 



3400 3000 



1700 



1100 



700 



cm 



1600 



Station 5 - FIGURE 6. Infra-red spectrometry of the resins. 

The distribution of saturated hydrocarbons determined by gas 
phase chromatography (Fig. 7) demonstrates the evolution which led to 
the degradation of the n-alkanes (5.99 % to 3.33 %) to n-C30 (Table 1). 
It should be noted that by March 31, 1978, this degradation appears to 
have begun. Thus there was an increase in the ratios of pristane/n-Cl7 
and phytane/n-Cl8 (Table 1). The isoprenoids degraded less easily than 
the n-alkanes (TISSOT and al . ) , but by June 1980 these compounds could 
no longer be detected. As degradation advanced, the contribution of the 
biogenic hydrocarbons increased, and n-alkanes of odd carbon numbers 
between n-C25 and n-C35 -- characteristic of the cuticle waxes of higher 
plants (Eglington and Hamilton - 1963) — appeared, confirming the ter- 
restrial contribution to the contents of organic matter in the sediments. 



Moreover, the disappearance of the n-paraffins points up a relative 
enrichment in the unresolved complex mixture of the isoalkane and cyclo- 
alkane compounds, and generally in the compounds around n-C30 . It was 
possible to demonstrate these last compounds by GPC/MS by measuring 
the masses : m/e 217 being characteristic of the tetracyclic 

117 



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118 



31-03-78 



jimuiuiiiJi 



1«7 



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22-11-78 




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17-1-80 



JS J'l 2S 




*s 



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24-6-80 



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27 
25 



'■N 



CG 

STATION 5 

FIGURE 7. Evolution of the saturated hydrocarbons. 

sterane compounds (CnH2n-G) eluted between n-C26 and n-C31, and m/e 
191 characteristic of pentacyclic triterpane compounds (CnH2n-8) 
eluted over n-C30 (Fig. 8 and 9) . This relative enrichment in cyclo- 
paraffins is confirmed by the mass spectrometry analysis of the 
fraction (Hood and O'Neal - 1958). Among the saturated hydrocarbons, 
(n+iso) -alkanes show a rapid diminution after March 31, 1978, and a 
stabilization thereafter ; cycloparaf f ins , principally 2-, 3- and 4- 
membered rings show an enrichment, and 5- and 6-membered rings are 
fairly stabilized (Fig. 10) . 



119 




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(Uvivis-s 



m«i«l 01 tOTiui tHiPwTiMS 



ST«! IONS 

FIGURE 10. Distribution of cycloparaf fins by mass spectrometry. 

In the aromatic fraction, chromatographic profiles showed : 

- a loss in light hydrocarbons as from March 31, 1978 ; 

- a positive response in flame photometric detector (FPD) , specific 
sulfur detector, throughout the period studied, which is significant, 
given the presence of sulfurous aromatic hydrocarbons (thiophenics) , 
and indicative of extensive continual pollution (Fig. 11) ; 

- a persistence of dibenzothiophene despite a decrease until June 1980 ; 

- an unresolved complex mixture similar to that of the saturated hydro- 
carbons. 

Metal (nickel and vanadium) and sulfur contents assessed through 
various samplings (Table I) confirm the persistence of the pollution, 
and do not indicate any significant evolution. The divergences observed 
may be attributed to variations in concentration of the two crudes 
present in the polluting mixture. It is to be noted that it is not 
possible to date to establish the cause of a relatively high peak at 
the level of the n-Cl6 in some saturated hydrocarbon chromatogram. 
A similar peak appeared at Station 6. 

Station 6 

Decontamination is virtually nil here. In June 1979 A maximum of over 
6,000 mg of hydrocarbons/kg of sediment was registered ; by June 1980 
hydrocarbon contents were still over 1,200 mg of hydrocarbons/kg of 
sediment (Fig. 4) . This is true of all stations where the marine cha- 
racter of the environment is least pronounced -- that is, in the upper 
reaches of the Aber. 



As can be generally observed in the stations, the most striking 
evolution is the degradation of the n-alkanes to n-C30. They appear 
to evolve very rapidly, since the very first sampling taken at this 
station on March 31, 1978 indicated that the ratios of pristane/n-C17, 

121 




PORTSALL 23-3-78 




AW 31-3-78 



FPD 



i-jji 



if 



T 



; 1_ 

.1 



a~^ 



M 



v # 



^J 



AW 22-11- 78 



4 

AW 20 6 -79 



M 



V 



"if 

i 



FPD 



,P 






,/Vl 



AW 17-1-80 



A'*" 



'-OJ 



V. 



M, 



\i 



AW 24-6-80 



_> 



STATION 5 



FIGURE 11. Evolution of aromatic hydrocarbons. 

122 



and phytane/n-Cl8 were among the highest and that this degradation was 
among the most advanced (Table I). In figure 5, a continual decrease 
in saturated hydrocarbons is noted over time (33 % on March 31, 1978 
— 22 % on June 24, 1980). In spite of a maximum aromatic hudrocarbons 
content observed in June 1979, they underwent the same type of evolu- 
tion (34.3 % on March 31, 1978 -> 24.8 % on June 24, 1980). The result 
is an increase in the relative contents of resins ; but it should be 
noted that in March 1978, polar compound contents (24.6 %) were higher 
at this station, which is located in the outer part of the Aber, than 
at Station 5 (17.2 %) where the marine character is more pronounced. 
This level held true until June 1979, when the increase became the 
same as at Station 5 . 

This phenomenon can be explained by the presence of polar com- 
pounds of terrestrial origin deposited by the river which flows into 
the Aber. This contribution of autochthonous organic matter is seen 
in the presence of n-alkanes of odd carbon numbers (n-C25, 27, 29, 31, 
33) in the aliphatic fraction, all the more accentuated by the signi- 
ficant acceleration in the degradation of the normal fossil paraffins 
(Fig. 12) The result is a relative enrichment in cyclic satured hydro- 
carbons (cycloparaf fins) — particularly of 3-, 4-, and 5-membered 
rings around n-C30 — which are less easily degradable . 

Chromatogram profiles of the aromatic hydrocarbons indicate how 
polluted the station is, principally in the FDP response (Fig. 13), 
where the persistence of dibenzothiophene and its alkylate derivatives 
(and also of naphthobenzothiophenes) may be noted. The stability of 
these compounds made it possible for us to use these chromatograms as 
the "fingerprints" of the pollution. 

As a matter of fact, according to the DGMK. report, biogenic 
hydrocarbons of terrestrial origin (recent sediments) are poor in 
aromatic compounds (< 5 %) , and particularly low in sulfurous com- 
pounds of the thiophenic type. 

The evolutions observed in the resins are similar to those at 
Station 5 ; an oxidizing degradation increases the oxygen contents 
(8.5 % in June 1980), and an upward curve is noted in the infra-red 
absorption bands of the hydroxyls and carbonyls, the latter of which 
are predominantly carboxylic acid compounds (Fig. 14). Metal and sul- 
fur contents remain fairly constant over time. 

Station 8 

This station was distinguished in being the farthest from the 
sea, in an area of sandy mud. Hydrocarbon contents show that the 
decontamination process at this station was virtually nil (Fig. 4) . 

An anomaly is noted in January 1980, when the hydrocarbon con- 
tents went over 5,000 mg-/kg of sediment. As we shall see below, this 
is due to pollution from petroleum cuts or fuel oil which was later 
deposited on top of the pollution under study (Fig. 15 and 16). Al- 
through information is lacking on some samples, which were too small, 
it can be seen that metal and sulfur contents remained very stable 
over time. 



123 



31-03-78 




L 



22-11-78 




20 - 06 - 79 




17- 1-80 



3331 



Ll%, 



M_J^O, 



% 



24 6 80 




'-jU^i 



"X 



CG 

STATION G 
FIGURE 12. Evolution of the saturated hydrocarbons. 



Examination of the chromatograms of the "saturated" fractions 
shows a quantity of biogenic hydrocarbons of terrestrial origin which 
is not negligible, and which is characteristic of the upstream sta- 
tions on the Aber which receive large quantities of deposits from the 
soils. The distribution of n-alkanes is in fact typical of that ob- 
served in the extracts from recent sediments in the predominance of 
odd-carbon-numbered n-alkanes from n-C25 through n-C35 (Fig. 16). 

These quantities of biogenic hydrocarbons present in the ali- 
phatic hydrocarbons are demonstrated in the ratio R29-31 developed 



124 



^^^^ 






4 


» 






I t 






" 


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*\ 


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) 


1 


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1 ! 

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1 




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s 


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l . 
i 


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^ 




PORTSALL 23-3-78 


AW 31-3-78 




FID ^\ ,1 


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li 

1 


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i 


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i • 1- 
AW 20 6 -79 


A 




AW 22-11-78 


\ 








A — i v ' 


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! 

i 


1 

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li' 




1 


f> 




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1 














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i 
j i 


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» ? 


i 




AW 17-1-80 


AW 24-6-80 





STATION 6 



FIGURE 13. Evolution of aromatic hydrocarbons. 

125 



i — r 

3400 3000 



1600 



STATION 6 



31-03-78 




FIGURE 14. Infra-red spectrometry of the resins. 



by Tissot et al ; they were calculated for the earliest samples only 

2(C29 + C31) 



R 29-31 = 



C28 + 2C30 + C32 



The relationship shows that in this case, the n-C29 and n-C31 
predominate. Where the value is over 1, the odd-numbered carbons pre- 
dominate. In Table 2, a compilation of these values for all the 
stations, it is seen that R is much higher than 1 at Stations 6 and 8. 

Even in March 1978, this presence of natural compounds modified 
the distribution of hydrocarbons by family : 

- saturated hydrocarbon contents were low ,- 

- polar-compound contents (resins and asphaltenes) high. 

While the ratio of SAT/ARO decreased slightly, as at Stations 5 
and 6 (Fig. 17), degradation of n-alkanes and isoprenoids (pristane 
and phytane) was observed throughout the period, showing clearly which 
polycyclic alkanes are most resistant to degradation. 

The chroma tograms of the aromatic hydrocarbons have very marked 
profiles under photometric detection (FPD) , and a persistence in the 
unresolved complex mixture (FID) (Fig. 16). Comparison of the results 
of the GPC with those of the high resolution MS undertaken on the re- 
ference samples of March 23, 1981 at Portsall, and the sampling taken 

126 



31-03-78 




22-11-78 



-^ 



20-06-79 




17-1-80 



29 



35. « 1 . 1 27 



«,a»% 






V 



24-S-IO 



,# 



IS 



% 



CG 

STATION 8 

FIGURE 15. Evolution of the saturated hydrocarbons. 

on June 24, 1980 at this station, shows a degradation (or dissolution) 
of the alkylated cycloparaf fins to C3 and C4 . Concerning the thio- 
phenic derivatives, some benzothiophenic alkyls disappear to become 
C5, while the initial alkylate derivatives of dibenzothiophene become 
C3 ; the naphthobenzothiophenes persisted. 

In the sampling taken in January 1980, an abnormally high res- 
ponse is noted — by Flame Ionization Detection (FID) and by Flame 

127 




PORTSALL 23-3-78 



FPD 






1/ --sj 



% 



AW 22-11-78 



irf**4 



n~r 



AW 20 6 -79 



'■si 



FPD 



"vm 



FID 



AW 17-1-80 



SK J 



-». ~t\ 




AW 24-6-80 



STATION 8 



FIGURE 16. Evolution of aromatic hydrocarbons. 
128 




AW 31-3-71 

FIGURE 17. 



AVV 20 6 79 



AW 22-11-78 „„ „ ..„ AW ,,.,.,„ 4W n t |D 

Evolution of the ratio of saturated hydrocarbons 
to aromatics. 



TABLE 2. Values of the R29-31 ratio. 

2 (C 29 + C 3 i) 
Valeurs de R29-31 = 



C28 + 2C 3 o + C 



12 



Station 


31.03.78 


2.05.78 


1 


1,02 


1,23 


2 


1,13 


- 


3 


1,10 


1,05 


4 


1,36 


1,07 


5 


1 ,23 


1,22 


6 


2,34 


1,35 


7 


1,26 


1,59 


8 


4,00 


2,78 


9 


1,06 


1,12 



129 



Photometry Detection (FPD) as well. This is caused by the presence of 
a light cut (gasoline, fuel oil, etc..) deposited on top of the Amoco 
Cadiz pollution (Fig. 16) . 

Here again the infra-red resin spectrum shows an increase in 
absorption of hydroxyls and the transformation of esters to acids 
(Fig. 18). The oxygen content of these polar compounds (7.4-7.5 %) 
confirms the degradation by oxidation. 



31 03 78 




3400 3000 



1700 



1100 



;oo 



cm 



1600 



Station 8 



FIGURE 18. Infra-red spectrometry of the resins. 
Stable Hydrocarbon/Water Emulsions or "Chocolate Mousse" 

When petroleum spreads over a marine environment, the movement 
of the waves, the wind, and the currents causes a very rapid emulsion 
with the sea water which is called "chocolate mousse". These stable 
emulsions are constituted by dispersing sea water in the hydrocarbons 
(inverse emulsions) . This type of emulsion was sampled during the 
first month after the accident (Fig. 19, Table 3). 

A program of analysis which is different from that used for the 
sediments and sands was employed (Fig. 20) . After purifying the emul- 
sions (of sand, algae, etc...), they were distilled to measure the 
water contents of those emulsions with boiling points below and those 
above 340°C. This method is described by Pelet and Castex. The results 
are assembled in Table 4. 



130 



BRIGNOGAN 


d ROSCOFF C^ 


• LANNION £ v 






TREOnrAN ^_j(Z^S~^ 
-**—>>» GUISSENY 
HEROENIEL J"**" 

( PORTSALL 


* HoRUAIX 








( BBESIW^ 






22, 23 mars 78 

3 avrll 7B 
A avrll 78 

18 octobre 78 
31 Janvier 79 
28 mars 79 


PORTSALL 
GUISSENY 

ROSCOFF 

PORTSALL 
GUISSENY 

BRIGIIOGAN 

KERDENIEL 

TREOMPAN 

KEROENIEL 
TREOMPAN 



FIGURE 19. Sampling stations. 



TABLE 3. Characteristics of the samples. 



Lie-jx 


Dates 


Ces r'" 1 --- ■ -'" cr - - 


P0=TSALL 

v,= :s=ll 

Z-.lll'i'- 

3 ~' r T r rr 


:2.::.7e 

Z3.:3.7- 

■T -t ?a 

3 . 1~ . ?z 


tt rcc--:rs. 

1 ; - : *. . _ <= c f "• - * 


SRISIIXW 


\i' o :._\-\;\r: .:,. 


[f-rof. - 35 z-) 

,,„,„_... 

►.E^3£-.: c .L 

K;=2EMEL 
(Prof. ■ 2E cm) 


re.::. 79 

26.G3.79 


1 



Moreover, on these fractions a simulated distillation curve was 
plotted (TBP or True Boiling Point) by gas phase chromatography accor- 
ding to the method of Petroff et al . (1981). 



Results of the distillation (Table 4) and the TBP on the PI-340°C 
(Table 5) indicate a loss by evaporation and dissolution of about 7- 
8 % of the light- hydrocarbons between March 22, 1978 and April 4, 1978. 

131 



r 



PIODUI7S F.ECUPEF.ES 
BRUT 



FArLE PTi.LUE ! 

I 



n 



DECANTATION 

FILTRATION 

CE'.'TPIFUGATION 



ZXTR-CT]rt\ "50SHLET CITJ , 






KSKYDRATATIOK Na : S3. 



PRODUIT EPURE 



P3DDUIT EPURE 



ETETACE 340°C 



'. POIDS 
S, Ni, V 



C — ) CUD (EE5> — © 



ASPHALTENES 



I POIDS PA8 
CKRO'LATOGRAPHIE C3UCHE MINCE 



1 1' 



HC.SATURES H: . ARO'IATIPJES RESIDES 



C G IS V 



IR 



FIGURE 20. The program of analysis 



TABLE 4. Results of distillations of samples of emulsified crude, 



1 


^- — L'r * ; Icvumcnt s 


PORTSALL 


PORTSALL 


GUISSENY 


ROSCOFF 


PORTSALL 


GUISSENY 


BRIGNOGAN 


| r< 


22 mars 78 


23 mnrs 1978 


3 jvril 78 


4 


•vril 1978 




* |>olilft e.iu Jans 
■ ttiu Lsitiit 

1 


71 ,7 


68,7 


67,7 


51 


60 


57 


57 


n < lio'c 


24,3 


20,0 


8.9 


13,15 


15,95 


13,05 


8,7 


: |iuid< lie 
IK - J40*C 


75,7 


80,0 


91,1 


R4.05 


86.95 


91 ,3 


86, 10 



Two samples (Guisseny, March 23, 78, and Brignoqan, April 4, 1978), 
lost considerably more. The latter was initially the point of highest 
contents. Its chromatographic profile (TBP) is also very different 
from that of the samples taken at Portsall on March 22 and 23 (Fig. 

132 



TABLE 5. Simulated distillations of PI-340°C. 



Z poids 






Temperatures 


'C 






cunules 


PORTSALL 


PORTSALL 


GUISSENY 1 PORTSALL 


CUISSENY 


R0SC0FT 


BRICNOGA.N 




22.3. 


23.3 


23.3 4.4 


4.4 


3.4 


4.4 


1 


162.2 


199,1 


223.6 216,3 


210.2 


227.3 


239,2 

I 


5 


193,4 


218,6 


248,2 233,4 


229,7 


245.5 


172,9 


10 


207,8 


228.7 


260,6 


246,7 


245,9 


257,8 


285,9 


20 


224,6 


245.0 


273,8 


264,2 


266,2 


271,4 


300,5 j 


30 


237,0 


256,1 


285,9 


275,8 


279,9 


284,8 


310,5 


40 


251,4 


271,7 


292,4 


286,3 


290,7 


292,9 


f 
319,6 


50 


267,9 


281 ,7 


300,6 


294,7 


300,9 


301,6 


326,5 


60 


282,7 


290,6 


306,5 


303,5 


308,9 


308,9 


J35.0 

i 


70 


295,2 


301,3 


317,0 


313,2 


319,2 


318,8 


343,6 


80 


310,6 


313,2 


326,0 


322,9 


329,9 


328,1 


353.9 


90 


330,6 


331,3 


343,0 


340,7 


346,8 


343.6 


371,0 


100 


392,1 


390,3 


400,9 


459,8 


439,3 


422,3 


460,0 



ei- ! :. ^:;:--y— -j- f-"|^-----i--= ■=£•■-( 


•": ' i i-'i-': : r.lr?~S=~~j"".=S ^1 1 


la- -!-.V .-- f- -. - : - = i- r-'-K'-T- j- -■' \ i- 


■---^r. 1 \i,\ ' t ■ 




^iM . 


fiT .-;-; r-f \\\k 


33-^- 


:-:.!•;: i-'i •: 1 ! '" :. 




::•..! II Mil 


; ■ ; . ji ■■, ■ ■ 1 i 









! r 

r r- 

I I I I 



a I - J-i-i- ! 'j f. 



-m_ii4- 



_.__!. 



l- 



.1 i 



' ;V 




FIGURE 21. "TBP" PI-340°C. 
133 



The chromatogram of the saturated hydrocarbons shows that the 
n-paraffins had disappeared (Fig. 22) . Although there are divergences 



FIGURE 22. Chromatogram of the saturated hydrocarbons taken 
at the Brignogan station April 4, 1978. 

in such parameters as metal and sulfur contents, the infra-red spec- 
trum definitely confirms that it is crude from the Amoco Cadiz. We 
believe that these differences may be due to the fact that we were 
dealing with oil sheets that had been treated to a greater or lesser 
degree. These observations should be compared with those made by 
Aminot et al. at the same time at a station just offshore from this 
one, which showed an abnormal loss of dissolved oxygen. He explained 
it as in-situ biodegradation of the hydrocarbons, which appears to be 
the only logical explanation. 

Distillation of the 340+ fractions shows little in the way of 
interpretable differences (Table 6) . The sulfur and metal (nickel and 
vanadium) contents show, by their stability, how important these com- 
pounds are as pollution markers (Table 7) . 

TABLE 6. Simulated distillations of 340+ residues. 



1 

Z poids 

discilUi 


P0RTSALL 
22.3 


P0RTSM.L 
22.3 


CUI'SEW 
22.3 


nperatures 

PORTSALl 
4.4 


C 

cuissncY 

4.4 


ROSCOFF 
3.4 


BRICNOGAN 
4.4 


1 


291,4 


283,8 


281,8 


305,1 


303,2 


295,8 


266,6 


5 


346,0 


325.2 


327.1 


338,9 


342,9 


336,1 


318,1 


10 


370,2 


346.9 


349.6 


359.4 


367,9 


360,8 


342,2 


20 


408.8 


383,3 


386.2 


394,2 


405.3 


399.5 


386,3 


30 


446,0 


420,3 


422,6 


431,3 


443.8 


439,5 


421,7 


40 


484,1 


457,5 


458.5 


463,7 


476.3 


472,7 


458.8 


50 


526,9 


497,8 


497.2 


499,3 


5,4.6 


515,7 


503,6 


60 




543,4 


540,2 


539.3 


558.6 




560,1 


1 


54,35 Z 
i 
547,3 


61 Z 

1 
547,5 


62,1 Z 
1 

548,6 


62,3 Z 

i 

549,6 


61.8 Z 

a 

568,6 


56.8 Z 
1 

548 


61.7 Z 
1 

569,4 



The breakdown by chemical family is shown in Table 8. It appears 
that the evolution of the crude in all of the emulsions is a sLow 
process. A slight decrease in the ratio of saturated to aromatic 

134 



TABLE 7. Sulfur, nickel and vanadium contents. 









S 


Ni 


V 


Ni/V 








Z pds 


Ug/g 


ug/g 






PORTSALL 


22.03.78 


2,33 


18,5 


62 


0,27 




PORTSALL 


23.03.78 


2,38 


14,0 


45 


0,31 


*» 

«•"! 


CUISSENT 


23.03.78 


2,38 


16 


50 


0,32 


■ 

3 


ROSCOJT 


3.04.78 


2,22 


14 


48 


0,29 


■ 


PORTSALL 


4.04.78 


2,30 


16 


58 


0,28 


B£ 


CUISSENT 


4.04.78 


2,18 


20 


65 


0,31 




BRICNOGAN 


4.04.78 


2,30 


22 


68 


0.32 



TABLE 8. Evolution by chemical family. 





PrSlevesents 


lies 


J pds 
H ,C . satures 


Z pds 
nC aronat. 


' pds 
Resines 


I pds 
Asphaltene: 


SAT/AROS. 


■ 


PORTSALL 
PORTSALL 


22.03.78 
23.03.78 


38,06 
37,28 


35.66 
34,12 


21,71 

24,28 


4,57 
4,32 


1,06 
1,09 


CUISSENT 


23.03.78 


41,69 


34,11 


16,40 


7,80 


1 .22 




PORTSALL 


22.03.78 


47,65 


31,29 


16,77 4,28 
(21,05) 


1,52 


1 

1 


PORTSALL 


23.03.78 


45,12 


34,55 


15,70 4,60 
(20,30) 


1,30 


i 


CUISSENT 


23.03.78 


39.45 


31 


24,90 4,60 
(29,50) 


1.27 

I 


u 




PORTSALL 


4.04.78 


46,75 


30,12 


19,18 3,95 
C3. 13) 


1,55 j 


id 

S3 


CUISSENT 


4.04.78 


46,38 


31,76 


17,65 i 4.21 
(21.86) 


1,46 




BRIGNOCAX 


4.04.78 


34,10 


31,50 


25,60 1 8,80 
(34,40) 


1,08 




RO SCOFF 


3.04.78 


43,69 


34,01 


16,96 5,34 
(22,30) 


1,28 




KERDENIEL 
(35 cm) 


18.10.78 


40,00 


33,50 


19.50 7,00 
(26.50) 


1,19 


■ 
II 

a 
■ 


TREOMPAN 


31.01.79 


33.90 


39 


19.20 | ' 7,90 
(27,1) 


0,87 


■ 


TREOVTAN 


28.03.79 


31,10 


36,90 


22,60 7,40 
'30.0) 


0,80 


i ffl 
U 


KERDENIEL 


28.03.79 


38.40 


36.90 


18,10 6,60 
(24,70) 


1 .04 




KERDENIEL 
(25 ca) 


28.03.79 


27,60 


26,30 


35,90 1 10,20 
(^6.10) 


1,05 



hydrocarbons is seen, however, as well as a slight relative increase 
in the polar compounds. The infra-red spectra of these compounds show, 
in fact, a slight upward curve in the absorption band of the carbonyls 



135 



between the end of March and early April 1978 (Fig. 23) . These results 
corroborate those of Roussel and Gautier at Antifer . ( 1979) . 




PORTSUl 22.3.78 



P0RT55LL 23.3.73 



GUISSEHY 23.3.. 78 



ROSCOFF 3.4.73 



PORTSALL 4.4.78 



/ G'JISSENY 4.4.78 



BRIG'iOGV* 4.4.7c 



1 1 1 

3600 3200 2600 



n 

1700 1600 



— I — 
1100 



750 cm 



FIGURE 23. Infra-red spectrometry of samples of crude 
(R 340+) and extracts. 



136 



The pathways followed by the crude are shown in the triangular 
diagram of the saturated and aromatic hydrocarbons, and the polar 
compounds (resins + asphaltenes) (Fig. 24). 



P, PortsMl 22.?3.7!< 

P, Portsoll 23.C3.7P 

t} Portiall 4. CM. 79 

G^ Gui99nny 23.C?.?" 

Cj Gulssany 4.G1.7*! 

5 Drlgnopan i."i.7° 

rc noicirr 3.r3.7i 



in / ••• 

/■■■■"> 



SM. 




00&mm§ 






RES.+ ASPH.) 



FIGURE 24. Triangular diagram of the distribution by chemical family. 

For the sake of comparison, we have added the corresponding values in 
samples of polluted sands and a subtidal sediment taken in the Aber 
Wrac'h (AW 9) . 

Intertidal Sediments - Polluted Beach Sands 

The program of analysis employed for the study of these sands is 
identical to that used for the subtidal sediments of the Aber Wrac'h 
(Fig. 2). The characteristics of these samples are seen in Table 3. 

The sulfur contents of these polluted sands (2.5-2.6 %) are all 
slightly higher than those of the emulsions — even the most advanced 
(2.3-2.4 %) , but are about the same as those in samples taken from the 
Aber Wrac'h. This evolution is explained by the disappearance of 



137 



certain chemical species which are easily degradable and/or soluble, 
such as n-alkanes, light aromatics, etc... leaving a higher relative 
concentration of sulfurous species, which are more resistant to degra- 
dation. Metal concentrations (nickel and vanadium) , and their ratio, 
did not vary significantly through the one-year pariod of the study 
(Table 9) . This behavior was noted above in the discussion of the Aber 
Wrac'h samples. 



TABLE 9. Sulfur, nickel and vanadium contents. 









S 


Ni 


V 


Ni/V 








5 pds 


Ug/g 


Ug/g 






KERDENIEL 


16. IP. 78 


2,55 


14 


45 


0,31 




(35 cm) 














TREO".FAN 


31 .01 .79 


2.65 


17,5 


83 


0,21 


u 


TREO^AN 


26.03.79 


2,66 


19 


65 


0,29 


s 


KTRDr.NIEL 


28.03.79 


2,69 


20 


85 


0,23 


u 


KERDENIEL 
(25 en) 


28.03.79 




18 


65 


0,28 



As we did with the samples of emulsified mousse, as described 
above (Fig. 24), we recorded the saturated and aromatic hydrocarbons, 
and the polar compounds (resins and asphaltenes) on the triangular 
diagram (Table 8) . 

The most notable evolution took place in the latest samplings 
of polluted sand. But it is difficult to isolate the factors contri- 
buting to evolution in the beach sands : time, extent of dispersion 
of' the crude, how long the oil was on the sea, the support material 
(sand, mud, rocks) . This is all the more true of a sampling taken a 
year after the catastrophe, which may have undergone a very complex 
history of burial before being picked up again by the water during a 
storm or a spring tide. Even with these reservations, however, it 
seems that the triangular diagram shows that the crude follows several 
pathways in its evolution : 

- a very short and stable pathway, as we saw above in emulsions on 
free water ; 

- a pathway in which a relatively slow disappearance of saturated 
hydrocarbons (n-alkanes) and aromatics (Mono- and diaromatics) 
results in a moderate increase in polar products, when the crude is 
trapped in sand ,- 

- an evolving pathway followed by crude which is trapped in more or 
less muddy subtital sediments of the Aber Wrac'h, as demonstrated 
above . 

The chromatograms of the saturated hydrocarbons in the polluted 
samples taken in 1979 all show a general degradation of n-paraffins to 
n-C30, confirmed by an increase in the ratios of isoprenoids to 
n-alkanes (n-C17 and n-C18). This degradation seems slower in polluted 
beach sands than in the sediments of the Aber Wrac'h. 



The mass spectrometry study of the (n+iso) distribution, and 
that of the 1- to 6-membered rings of cycloparaf f ins confirms this 

138 



evolution (Table 10, Fig. 25). But a slight alteration is seen in sur- 
face samples (Kerdeniel, March 28, 1979), which may be explained by 
the reemergence of masses of only slightly degraded crude, which have 
been trapped in sand, during a storm. 

TABLE 10. Distribution of the cycloparaf f ins by the mass spectrometry. 





I vol. 






Z vol de cyclanes a 






Prelevements 


paraf fines 
(n + iso) 














1 cycle 


2 cycles 


3 cycles 


4 cycles 


5 cycles 


6 cycles 


P0RTSA1L 


52.92 


14.20 


13.07 


8,20 


5.87 


2,81 


2.33 


23.03.78 
















Gl'ISSEKY 


55.66 


14,29 


13,04 


8.05 


5.30 


2,07 


1.59 


C3 .03. 78 
















5JSC0FF 


53,13 


14,09 


13.50 


9, I 1 


6,22 


2.69 


1.19 


3.0- .76 
















?0RTSALL 


47,49 


14,44 


14,80 


10, 16 


7,46 


3,31 


2,34 


4.04.78 
















GCISSINY 


46,33 


16,88 


15,78 


10,43 


7,73 


2,29 


0,55 


4. 04. 76 
















BRIC7N0GAN 


31,90 


22,15 


19,72 


12,24 


8,52 


3,64 


1,83 


4.04.78 
















TRIOS AN 


35 


17,12 


18,13 


13,20 


9,74 


4,26 


2.54 


31 .01.7? 
















TRIOSAN 


30,93 


17,75 


19,42 


14,24 


10,21 


4.59 


2,86 


28.03.79 
















KERTEXIEL 


44,52 


15,58 


16,17 


10,92 


7,52 


3,1 1 


2,18 


28.03.79 
















KER3ENIEL 


31,88 


11,23 


15.97 


16,07 


13,99 


6,80 


4,06 


28.03.79 
















(25 ex prof 


) 
















"T» MCI" 



r T r, iirL .'f ,i" . '-■ 



'.r"D r NIFL ? n .'n.?'< 



T'lFO^'A'l 31.01. '9 

PTin\"ir.n\ i.n.;n 

GIJISSFNY 1.04,/n 
I"31TSA.IL 1."'1.'1 

P'-ttt J. (14. 711 
CUI5PFMV ?l.'n.71 

-*■ 

Nomhro dn nnynu« (n«pht>lnml 

FIGURE 25. Distribution of the cycloparaf fins by the mass spectrometry. 

139 



It should be noted that a sample taken at the same time and same 
place, but at a depth of 25 cm, shows an advanced stage of degradation, 
comparable to that observed in samples from the Aber Wrac'h at the 
same time. 

Compared with these subtidal sediments, oxidation degradation of 
the trapped crude in beach sands is slight and slow. This is seen in 
the infra-red spectra of the resins, where the absorption bands of the 
carbonyls are less marked (Fig. 26) . 




KERDENIEL 18.10.78 



treo:ip*:i 31.1.79 



TREO'IPAN 28.3.79 



KERDENIEL 28.3.79 



t r 

3600 3200 



FIGURE 26. Infra-red spectrometry of the resins, 



CONCLUSION 

The samples studied fall into three categories : 

- subtidal sediments (Aber Wrac'h) ; 

- oil/water emulsions or "chocolate mousse" ; 

- intertidal sediments (beach sands) . 

In the slightly muddy sediments of fine sand in the stations lo- 
cated in the outer part of the Aber Wrac'h, where the marine character 
is pronounced, a decrease in global contents of extractable compounds 
is observed, whereas in those located in the upper part of the Aber, 
the decontamination process is slow, probably inhibited by the muddy 
nature of the sediments. 



140 



The degradations observed in these sediments results in : 

- the progressive disappearance of saturated hydrocarbons, principally 
the normal paraffins ; 

- the disappearance of the light aromatic hydrocarbons ; 

- the oxidation of the polar compounds (esters, acids, etc...). 

The compounds which persist are : 

- the saturated polycyclic hydrocarbons and the heavy aromatics ; 

- sulfurous aromatic hydrocarbons of the thiophenic type ; 

- resins and asphaltenes, resulting in stable metal (nickel and vana- 
dium) and sulfur contents. 

In the sediments samples in the area of the Aber, terrigenic de- 
posits are superposed on the Amoco Cadiz crude, resulting in : 

- an increase in polar compounds — resins and asphaltenes. The in- 
crease in asphaltene contents is due to the presence of pigment 
(green) of chlorophyllaceous origin ; 

- the appearance of n-alkanes of odd carbon numbers (n-C25 through 
n-C33) . 

The most striking evolution in the "chocolate mousse" samples is 
the loss of light hydrocarbons due to evaporation and dissolution. 
Volatile compounds under C14 were not considered in this report. 

The samples of polluted sand taken from the beaches a year after 
the accident show a degradation phenomenon principally affecting the 
saturated hydrocarbons, and among these, principally the n-paraffins. 
There is an increase in the contents of polar compounds. But our in- 
formation is not adequate to state at what point in the history of 
these samples, the degradation was most intense. 



141 



REFERENCES CITED 

Aminot, A., 1981, Actes du colloque, Brest, Nov. 1979 : Amoco Cadiz , 
Consequences d'une pollution accidentelle par les hydrocarbures , 
CNEXO, Paris, pp. 223-242. 

Rapport DGMK. Rapport de recherche 150. Methode de dif ferenciation des 

hydrocarbures biogenes et des hydrocarbures d'origines petrolieres. 

Ducreux, J., Marchand, M., 1981, Actes du colloque, Brest, Nov. 1979 : 
Amoco Cadiz , Consequences d'une pollution accidentelle par les 
hydrocarbures, CNEXO, Paris, pp. 175-216. 

Eglington, G., Hamilton, R. J., 1963, The distribution of alkanes. 

Chemical Plant Toxonomy. T. Swain Ed., Acad. Press, pp. 187-217. 

Hood, A., O'Neal, M. J., 1958, Preprint of I. P., Hydrocarbon Research 
Group and ASTM. Committee E14 Joint Conference on Mass Spectro- 
metry, University of London Senate House, Pergamon Press. 

Pelet, R., Castex, H., Juillet 1972, Atlas de references de pollutions 
petrolieres. Rapport IFP n° 22 422. 

Petroff, N., Colin, J. M., Feillens, N., Follain, G., Juillet-Aout 1981, 
Revue de l'Institut Francais du Petrole, Ed. Technip, Vol. 36, 
n° 4, pp. 467-484. 

Roucache, J., Hue, A. Y., Bernon, M., Caillet, G., Da Silva, M., 1976, 
Application de la chroma tog raphie couche mince a 1' etude quanti- 
tative et qualitative des extraits de roches et des huiles. Revue 
IFP, Vol. XXXI, pp. 67-98. 

Roussel, J. C, Gautier, R., 1981, Actes du colloque, Brest, Nov. 1979 : 
Amoco Cadi z , Consequences d'une pollution accidentelle par les 
hydrocarbures, CNEXO, Paris, pp. 135-147. 

Tissot, B., Pelet, R., Roucache, J., Combaz, A., Utilisation des al- 
canes comme fossiles geochimiques indicateurs des environnements 
geolog iques . Rapport IFP, ref. 2 3 440. 

Unterzaucher, 1940, Ber. Deut. Chem. Ges., 73 B, pp. 391. 



142 



THE AMOCO CADIZ OIL SPILL 
DISTRIBUTION AND EVOLUTION OF OIL POLLUTION IN MARINE SEDIMENTS 

by 

Michel Marchand, Guy Bodennec, Jean-Claude Caprais, and Patricia Pignet 

Centre Oceanologique de Bretagne - CNEXO 
BP 337, 29273 BREST CEDEX, France 



INTRODUCTION 

In March 1978, the supertanker AMOCO CADIZ was stranded on shallow 
rocks off Portsall (north Brittany), 2.5 km from the coast. Two hundred 
twenty-three thousand tons of a mixture of Arabian light crude oil 
(100,000 t) and Iranian light crude oil (123,000 t) flowed into the sea 
without interruption from 17 March to 30 March. The maximum extent of 
the oil slicks is presented in Figure 1. At this point, about 360 km of 
coastline were polluted by the oil. 

The analyses of oil in seawater, measured by UV fluorescence spec- 
troscopy (Marchand and Caprais, 1981), revealed that the oil spill 





«°W »° 


*° 




3 jo 










a 

Ou«'n<i*y 


■ 


AMOCO CADIZ A 






"*• Angto No'itiind«l 




CARTE D EXTENSION MAXIMALE ^^^H 
ENUER OES NAPPES O HVDROCARBURf S ^fl 






^~ SrS 


A3f 


DU 17MAAS AU 28 AVRlL 19J8 ^H 














IV^^^g"* L Q N N IOW 




e 






\*MORl Ai» 


12 24 M 4* urn 

■1. ■■! 1 !■ 


48° 


P i^ev ejrf)/o""d*i"' Of i Vfj- c \j- c--tt>e 


1 








^ ^JT^^OfiQURE i 




g* 5 o t> 


v> 


■> 


JO . ?» 



FIGURE 1. Maximum extent of oil slicks on the sea surface, 17 March to 
26 April 1978. 



143 



affected a very large section of the western English Channel. One month 
after the AMOCO CADIZ wreck, the most polluted areas were located in the 
coastal zones, such as the Aber zone (38.9 + 6.7 ug/l) , the Bay of 
Morlaix (11.5 + 5.1 ug/1), and the Bay of Lannion (10.7 + 3.0 ug/1) . 
Analysis of samples from various depths revealed that the contamination 
extended throughout the water column. The 49°N parallel roughly con- 
stituted the northern limit of pollution. Beyond this limit, oil in 
surface seawater was not observed (1.6 + 0.5 jug/1) . In March 1979, one 
year after the AMOCO CADIZ stranding, hydrocarbon concentrations 
returned to a normal level (below 2.0 ug/1) ; however, some residual 
traces of pollution were still observed near the Abers and at the bottom 
of the Bay of Lannion (about 2.0 ug/1). 

We also began a chemical follow-up study of oil pollution in marine 
sediments. Some data have already been presented during the interna- 
tional symposium held in Brest (France) in November 1979 (CNEXO, 1981; 
Ducreux and Marchand, 1981; Marchand, 1981; Marchand and Caprais, 1981) . 
In this document, results of our study are presented in three 
parts: (1) oil pollution in sediments collected from the western 
English Channel one month after the wreck, (2) specific study in the 
Bays of Morlaix and Lannion to determine the distribution of oil 
pollution in surface sediments and at various depths, and the evolution 
of oil contamination over one year, and (3) specific study of the Aber 
Wrac'h to determine oil evolution from 1978 to 1981. 



MATERIAL AND METHODS 

Surface marine sediments were collected in the western English 
Channel with a Shipek grab. In coastal areas, small Ekman and Hamon 
grabs were used. The samples, after freezer storage, were dried by 
using a Soxhlet apparatus or by stirring with chloroform. The organic 
extract was concentrated to dryness, then dissolved with 10 ml of carbon 
tetrachloride. A first indication of petroleum pollution in sediment 
was obtained through a direct analysis of nonpurified extracts by IR 
spectrophotometry (Perkin Elmer 397). Quantitative measurements were 
carried out at 2920 cm corresponding to the presence of hydrocarbons 
and polar compounds. The data also reflect coextracted natural 
substances (fats, fatty acids, etc.) from sediments. The IR 
spectrophotometer was calibrated with a mixture of Arabian and Iranian 
light crude oils. 

Hydrocarbons were analyzed after cleanup of organic extracts on 
activated Florisil (200°C) in glass columns (15 cm x 0.6 cm i.d.). 
Hydrocarbons were eluted with 15 ml of carbon tetrachloride and measured 
by IR spectrophotometry. For some samples, organic carbon was 
determined with an auto-analyzer LECO WR-12. In a joint study with the 
French Petroleum Institute concerning the Aber Wrac'h sediments (Ducreux 
and Marchand, 1981), we compared the gravimetric determinations and the 
IR spectrophotometr ic analysis of nonpurified organic extracts. Results 
of the two methods are similar (Fig. 2). We also compared the IR 
spectrophotometric results obtained on nonpurified and purified organic 
extracts from some Aber Wrac'h sediments. In this case, correlation was 
significant (Fig. 3) . 

144 



EXT tPPMJ 

15000.00 



I0B2H 0$ 



5B0B.0E. 



RMDCD CRDIZ SEDIMENTS DE L HBER HRHCH 

ME5URE DE5 EXTRA ITS DRSHNIOJES 

SRRVIHETRIE CEXT: i SPECTROPHOTOMETR I E IR CHCJ 



a.ra 
0.0a 

FIGURE 2. 




IB0B0.B0 



hc cppm: 



15000.00 



gflfl fl .00 

Correlation between gravimetric determinations and IR spec- 
trophotometry measurements for organic extracts. 



CHC1 PURIFIES CPPM3 



I SBB . 03 . 



iB3a.ua. 



500.08 .. 



RMOCD CHDIZ SEDIMENTS DE L FIBER WRROH 

MESURE DE5 EXTRP, I TS DRGRN I QUES PRR 5PECTRDPHTDMETR I E I . R 
EXTRHIT5 NDN PURIFIES ET PURIFIES 5UR FLDRISIL 




CHC3 NDN PURIFIfS 

Ci : r.M] 

3 



FIGURE 3. 



Correlation between IR spectrophotometr ic measurements for 
nonpurified and purified organic extracts. 



145 



OIL POLLUTION IN THE WESTERN ENGLISH CHANNEL (APRIL 1978) 

One month after the wreck, sediments were collected during an 
oceanographic cruise (R/V SUROIT) to assess sea bottom contamination of 
the western English Channel. The sampled sediments were coarse- to 
medium-grained calcareous sands (more than 70% CaCo,) . In the Bays of 
Morlaix and Lannion and near the Aber zone, the content of calcium 
carbonate in the sands was somewhat lower (50-70% CaCO-) . Organic 
carbon content was generally low, from 0.02 to 0.6 percent (m = 0.18% 
+ 0.13%). The oil concentrations in the sediment ranged from 10 to 
1,100 ppm (nonpurified organic extracts) (Marchand and Caprais, 1981). 
Generally, the zone of contaminated sediments reflected offshore and 
coastal areas impacted by the drifting slicks (Fig. 4). The pollution 
of the sea bottom was a result of the diffusion of oil into the water 
column. Off Sept-Iles, a gradient was observed from the coast to the 
open sea (210, 52, 42, 34 ppm). At the 49°N parallel, from west to 
east, one could observe an increasing and decreasing gradient (21, 19, 
48, 102, 54, 52, 24 ppm). The highest petroleum accumulation in marine 
sediments were located in the coastal and sheltered zone of the Abers 
(100 to more than 10,000 ppm) and in the Bays of Morlaix and Lannion (10 
to more than 1,500 ppm) (Fig. 5). 




FIGURE 4. Oil pollution in marine sediments (April 1978) 
Concentrations expressed in ppm. 



146 



<a» 



baie 

DE MORLAIX 



3.*o 


• pod«r 




ME J ?L^'^~ rf /^ 








1 
1 

3 


Known (Kioi of oil 
accumulation in todifflanti 

Abtr Btno.t 
*b«r Wrac'h 
Riviftrt d* Ptnit- 








*" ^/ 








4 


Rivitr« dc Mortaia 






4* 


■<•** y^ 





s 


10Km. 


5 
1 


Point* dt Pnmtl 








Baia do lonmon 



FIGURE 5. Known coastal areas of oil accumulation in sediments. 



BAYS OF MORLAIX AND LANNION (JULY 1978 TO FEBRUARY 1979) 

A survey was undertaken from July 1978 to February 1979 to follow 
oil degradation within bottom sediments of the Bays of Morlaix and 
Lannion. In August 1978, specific sampling of some stations was made by 
the BRGM (Bureau de Recherche Geologique et Miniere) . At these stations 
(Fig. 6), several-meter-long cores were taken by vibracoring to 
ascertain the vertical distribution of oil in sediments. 



Oil Pollution in Surface Sediments 

The sedimentary description of sediments coLlected from July 1978 
to February 1979 is given by Beslier (1981) and Beslier et al. (1981) . 
The weathering of hydrocarbons in some polluted samples was studied by 
Boehm et al. (1981). In July 1978, the hydrocarbon concentrations 
(determinations made on purified organic extracts) ranged from 8 ppm to 
more than 1,500 ppm. Average concentrations are presented in Table 1. 
Complete data are given by Marchand and Caprais (1981) . 

We also used the parameter of total hydrocarbons/organic carbon 
(HC/OC) to demonstrate pollution of surface sediments. This ratio 
(HC/OC x 10 ) ranged from 48 to 6,065. Marchand and Roucache (1981) 
showed in a study of another oil spill in Brittany (BOHLEN wreck) that a 



147 













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I2S \ 














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U Of B*'J 




BAiE OE LANNION 


114* 1 
•1T4B J 
> 115 { 
• 116 » V^. 








nOSCO*' 














n A>i..5. •' M ' u 'i 




■ 107 


■ 117 ^ —— 










R.MEL 


• 106 


'l 3 C 








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• 112 \ 








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.110 ">23 / 








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7 


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t-^"^ \ !03» \ 














\ '02. \ 














V^ 101"«\ 














^%iOO \ 














' /^ 














• MOALA1I 













FIGURE 6. Sampling stations in the Bays of Morlaix and Lannion. 



TABLE 1. Average hydrocarbon concentrations in surface sediments in the 
Bays of Morlaix and Lannion (July 1978) . 



AREA 


SEDIMENT 


Number of 
observations 


Hydrocarbon 
concentrations 








(.ppinj 


BAY OF v nRL<UX 




25 


311 - 418 


. Morlaix river 


coarse sand to 
sandy mud 


6 


267 - 88 


. East area 

around Primel 


coarse sand to 
fine sand 


8 


600 - 656 


. Central area 
Vest area 


coarse sand to 
muddy sand 


7 


116 - 100 


. Penze river 


coarse sand to 
muddy sand 


4 


145 - 96 


BAY OF LV.M0N 




22 


188 - 213 


. North West area 


fine sand 


2 


41 - 43 


. South lie Grande 
marsh 


coarse sand 


2 


298 - 140 


. Central area 


coarse sand to 
fine sand 


9 


182 - 138 


. South East area 


fine sand 


9 


204 - 298 



148 



ratio of more than 100 is an index of oil pollution in surface sediments 
(Table 2). In this study, only four samples had a ratio less than 100; 
80 percent of collected samples had a ratio more than 200; and 28 
percent had a ratio more than 1,000. This simple parameter confirmed 
that the surface sediments were highly contaminated. 

Three sedimentary oil accumulation areas were recognized in the Bay 
of Morlaix: the Morlaix River, the Penze River, and the east area of 
the bay around Primel. In the Bay of Lannion, pollution was located 
beyond a line joining Beg An Fry and the lie Grande marsh (Fig. 5) . On 
the whole, from July 1978 to February 1979, the decontamination process 
was related to two essential factors: sediment type and the energy 
level of the geographic zone. Among muddy and fine-grained sands, a 
slow decrease in oil content was observed, whereas in areas more exposed 
to high energy conditions, as around Primel in the eastern part of the 
Bay of Morlaix, the fine- and coarse-grained sand bottom was rapidly 
cleaned (Table 3) . 



TABLE 2. Ratio of hydrocarbons/organic carbon (HC/OC) in unpolluted and 
polluted surface sediments (from Marchand and Roucache, 1981) . 



LOCATION 


Number of 
samples 


HC 
(ppm) 


Hf » 


REFERENCES 


UNPOLLUTED SEDIDMENTS 










English Channel (France) 










- estuary of Seine 


3 


30 - 40 


16 - 31 


TISSIER, 1974 


- bay of Veys 


2 


31 - 51 


26 - 53 


TISSIER & OUDIN, 
1973, 1975 


Iroise sea and bay of 
Audierne (France) 


23 


3.6-109.5 


21 - 70 


MARCHAND & ROUCACHE, 
1981 


NW Atlantic 


9 


1.3 - 19 


10 - 41 


FARRINGTON & TRIPP, 
1977 


Gulf of Mexico 


60 


1.5-11.7 


9-23 


GEARING <U a£.1976 


POLLUTED SEDIMENTS 










English Channel (France) 










- Estuary of Seine 


3 


230 - 920 


232 - 430 


TISSIER, 1974 


- Estuary of Seine 


3 


70 - 170 


276 - 283 


TISSIER & CUDIN, 
1973, 1975 


N-W Atlantic (coastal zone) 


6 


113 - 2900 


120 - 180 


FARRINGTON & TRIPP, 
1977 


Bay of Narragansett (USA) 


4 


350 - 3560 


313 - 724 


FARRINGTON & QUINN, 
1973 


Bay of Narragansett (US\) 


8 


520 - 5410 


1350-15590 


VAN VLEET & QUINN, 
1977 



Bay of Morlaix and Lannion 



45 



9 - 1S47 . 48 - 6065 present study 

I in : 9SU1237 
i +0 : 



149 



TABLE 3. Average hydrocarbon concentrations (ppm) in the sediments in 
the Bays of Morlaix and Lannion from July 1978 to February 
1979. 



AREAS 


•July 1978 


November 1978 


February 1979 


Bay of Morlaix 


311 - 418 


168 - 246 


172 - 262 


- Morlaix river 


267 - 88 


185 - 82 


169 - 80 


- Penze river 


155 


22 


97 


- East area (Primel) 


600 - 656 


53 - 54 


19 - 21 


Bay of Lannion 


281 - 262 


130 - 113 


126 - 110 



Oil Pollution in Core Sediments 

In August 1978, 24 several-meter-long vibracores were taken to as- 
certain the vertical distribution of oil incorporated into bottom 
sediments. Complete data concerning sedimentary characteristics and oil 
chemical analysis are presented by Marchand and d'Ozouville (1981). A 
comparison of grain size analyses of surface (Hamon) grab and vibracore 
samples revealed some differences. The vibracoring technique disturbed 
the first 10 cm of surface sediment layer as expressed by a shortage of 
fine particles. In another respect, we noticed that hydrocarbon levels 
in surface layer sediments were low, from 1 to 50 ppm (m = 22 + 19 
ppm), except for two stations in the Bay of Morlaix (AF 132: 100 ppm; 
AF 139: 174 ppm) . These values were lower than those reported for 
surface sediments collected by the Hamon grab in July and November 1978 
(Table 4) . These observations are an indirect confirmation that oil is 
inclined to be adsorbed on fine sedimentary particles. 

Hydrocarbon analyses of deep layers in the sediment cores did not 
reveal any significant vertical penetration of oil. Organic extract 
(EXT) and/or hydrocarbon (HC) concentrations very often remained 
homogeneous in the whole of the cores. The most important levels were 
found in the first 20-30 centimeters, corresponding to the layer sampled 
by the Hamon grab. A diving survey undertaken during the same time by 
d'Ozouville et al. (1979) gave the same conclusion: the depth of oil 
penetration was usually given to less than 7 cm, possibly related to the 
depth of biological reworking. Table 5 presents some results showing 
the absence of a deep diffusion of oil into bottom sediments. Reference 
data relating hydrocarbon content to sediment type for 17 cores are 
presented in Table 6. 



150 



TABLE 4. Comparison between hydrocarbon concentrations (ppm) observed 
in surface sediments according to sampling techniques. 



STATION 


HAMON 


GRAB 


VIBRATORY BORING 


July 1978 


November 1978 


August 1978 


102 


291 


276 


36 


103 


392 


228 


49 


112 


914 


- 


50 


114 


207 -' 367 


2S 


4 


122 


79 


- 


22.5 


124 


72 


- 


16 


132 


292 


56 


100 


138 


1547 


130 


29 


139 


60 


- 


174 


151 


211 


79 


4 


154 


- 


- 


8 


227 


- 


- 


< 5 


in 


403 - 447 


132 - 100 


41-6 



TABLE 5. Hydrocarbon concentrations (ppm) in some sediments cores from 
the Bays of Morlaix and Lannion. 



^\Station 


A F 


A F 


A F 


A F 


Depth n. 
(cm) 


112 


122 


132 


139 


0-10 
10 - 20 


50 


1 


22.5 


100 
< 5 


174 


20 - 30 






< 2 


11 


30 - 40 






< 2 


19 


40 - 50 
50 - 60 


4 




< 5 






< 2 


60 - 70 


< 2 


< 5 







151 



TABLE 6. Average concentrations of organic extracts (EXT) and 
hydrocarbons (HC) in sediment cores collected from the Bays of 
Morlaix and Lannion. 



s. 


nip 1 c 


Depth of 
coring (m) 


Sed iment 


(n) 


(EXT) 
ppm 


(n) 


(HC) 
ppm 


Al 


id: 


1 .S 


mud 


(8) 


231 l 80 


(7) 


26 « IS 


Al- 


103 


7.2 


mud 


(14) 


220 s 73 


(11) 


23 S 23 


Al 


104 


3.2 


medium to coarse sand and 

maerl 


(8) 


16 115 






Al 


1 1 J 


4.0 


fine to coarse sand 




- 


C6)<*> 


< 2 - 4 


Al 


1 14 


1 .3 


medium to coarse sand and 
maerl 




- 


(5) 


< 2 - 4 


Al 


1 JJ 


6.8 


fine sand 




- 


8 <*> 


< 2 


A I 


1 :4 


5.5 


fine to coarse sand 




- 


8 (*> 


< 2 - 6 


Al 


i :" 


2.1 


medium to fine sand 


(8) 


14 t 9 






Al 


i ?: 


1 .5 


maerl and silt 


(S)<« 


26 i 4 


3 (*) 


< 2 


Al 


1 3S 


2. 1 


fine sand 


7 (« 


14 t 7 




- 


1 v, 


1 vj 


2.7 


fine to coarse sand 




- 


6 ( *» 


< 2 


■ Al 


1 i - 


2.0 


medium to fine sand 


(9) 


10 * 10 






i M 


1 ". 1 


2.0 


fine to coarse sand 




- 


(8) 


< 2 - 5 


1 A ' 


Id 3 


2. 1 


medium to fine sand 


(7) 


13 t 3 




- 


! Al 


ISU 


2.3 


coarse to fine sand 


(7) 


26 • 6 






1 '"'' 


P.. 1 


2.5 


medium to fine sand 


(7) 


10 1 6 






1 A ' 


J 3 7 


,., 


fine sand to sandy mud 




- 


(6) 


< 5 



(*) : excepted surface layer, 

(n) : number of observations, 

(EXT) : IR spectrophotometry determinations of non-purified organic extracts, 

(HC) : IR spectrophotometry determinations of purified organic extracts on florisil. 

ABER WRAC'H (1978 TO 1981) 

The two Abers (Benoit and Wrac'h), located 8 km east of Portsall, 



were heavily impacted during the spill, 
estuaries, 10-15 km long and about 1 km wide 
to March 1979 (Marchand and Caprais, 1981) 
sediments throughout the Abers were heavily 
were more than 100 ppm and, as in a muddy 
sometimes reached higher than 10,000 ppm. 
Caprais (1981) showed that the natural 



These Abers are small 

A study from March 1978 

revealed that the bottom 

polluted. Concentrations 

area in the Aber Benoit, 

After one year, Marchand and 

decontamination process was 



related to the nature of the sediment and the energy level of the 
geographic zone. The fine- and medium-grained sands located in the 
exposed, downstream part of the Aber Benoit were well decontaminated 
(average hydrocarbon content reduced from 700 to 27 ppm) . On the other 
hand, in mud-dominated areas, the sediment acted as an oil trap (oil 
content above 10,000 ppm) and decontamination was not observed. For the 
Aber Benoit, oil pollution of mud-dominated zones such as Loc Majan will 
be long term. 

In the Aber Wrac'h, the evolution of oil pollution in the bottom 
sediments has been followed since March 1978. The location of sampling 
stations is presented in Figure 7; analyses for hydrocarbon and organic 
carbon concentrations are presented in Tables 7 and 8, respectively. 
Organic carbon concentrations ranged from 0.08 to 3.32 percent. 
Sediments are much more homogeneous than those of the Aber Benoit. 
Composition, with the exception of station 3 located at the mouth of the 
Aber, varied from slightly muddy to muddy sands. 



152 



FIGURE 7. Sampling stations in the Aber Wrac'h. 

ABER WRAC'H 




TABLE 7. AMOCO CADIZ oil pollution in the sediments of the Aber Wrac'h. 
Data collected from 1978 to 1981. OC = organic carbon; CaCO- 
= carbonate calcium; EXT = gravimetric determination of 
organic extract; OIL = IR spectrophotometric determination of 
nonpurified organic extract; HC = hydrocarbons, IR 
spectrophotometric determination of purified organic extract; 
(S) = surface; (P) = 10-15 cm depth. 



DATE 


T 

(months) 


SAMPLING 

STATION 


1 


2 


3 


4 


5 


6 


7 


8 


9 


Hatch 31, 
1978 


0,5 


0C (Z) 
EXT (ppm) 
OIL (ppm) 


0.53 
2130 
2051 


2.42 
11220 
12000 


0.2J 

71 1 
773 


0.96 
2185 

24 50 


1 .06 
3160 
3706 


1.03 
765 

839 


0.66 
2259 


1.94 
397 
953 


0.78 
1951 

206.1 j 


Kay 5, 

1978 


1.5 


CaCO Z 

0C 

F.XT 

OIL 


0.66 
2400 
307 3 


- 


0.34 
800 
1020 


1.59 
1 1490 
1 1750 


18.8 
0.71 
2000 
2970 


20.8 
0.78 
1660 
1380 


7.0 
0.61 
1 190 
1236 


8.3 

0.55 
460 
503 


is. j ; 

o.ao i 

2I6U i 
22 16 


November 22, 
1978 


8.25 


EXT 

OIL 


990 
1'.39 


4030 

4144 


130 
148 


3740 
3598 


2600 
2481 


710 
781 


1600 
1 105 


680 
67 1 


856 j 
872 


February 22, 

1979 


1 1.25 


OC 

f.XT 

OIL 


0.56 
1 1 '.0 
1589 


1.53 
2660 
2679 


80 
1 1) 


0.75 
1 140 
1301 


0.85 
1360 

I26B 


1.12 
3020 
25 56 


1 .00 
1050 
14 10 


0.60 

870 
I2h6 


1 
I78H . 

1677 ', 


June 20, 
1979 


15.25 


FXT 
OIL 


1550 
14 58 


1200 

1 124 


80 
74 


480 
4 12 


1450 
1 178 


6070 
4900 


1260 
1325 


1450 
1445 


8 30 ; 
■128 i 


October 22, 
1979 


19.25 


OIL 


715 


1374 


80 


1237 


1047 


2712 


2496 


485 


5„9 | 

1 


January 20, 
1980 


22.25 


OIL 


1408 


2567 


- 


1796 


1473 


1861 


1399 


5694 


iiw; ' 


June 1980 


27 


OC 

OIL 

HC (ppm) 


0.44 
442 
175 


1.74 
1892 
995 


0.08 

42 


1. 15 

1225 

724 


0.81 

1075 

348 


2.40 

I7BH 

_ 1 12 2 

2.70(S 
?.nl(l' 
2 320(S 
1 7HM(P 
83KS 

i iur 


1 .90 

1280 

602 

1. 12(S 
p. I<)(P 
(3167(S 
p 369(1' 
,I644(S 
jMHlir 


1 .67 
1628 


.1.00 j 
81.6 1 

. .0 i 


January 1981 


14 


OC 

OIL 

HC 


11.83 

321 

62 


0.84 

562 
255 




0.90 

34 7 

1 105 


0. 711 
4 56 
205 


0. litS 
2. M(P 

1 17b(S 
112 1(1' 
6 JO ( S 
4 20(1' 


1 i.m 

:! ,,: 

>i ; 

1 214 1 

! 

0|9(S1 i 

I437U') 

) 3I2(S> ; 

j 707U'l ' 


March 16, 
1981 


36 


OIL 
HC 


432 
229 


I07H(S 

30J(P 

43KS 

90(1' 


) 25 

) 

) - 

) 


!970(S) 651(S> 
627(1') |l*7l(l' 
55KS) |28I(S) 
403(P) |787(1') 


I5I7(S 

20201 P 

674(S 

722(P 


180 
40 


9iO(S 
1807(1' 
4I5(S 
642(P 


June 23, 
1581 


39,2 5 


Oil. i 308 
HC 50 


B5KS 

404 (P 

362(S 

71 (P 


) - 
) 

) - 

) 


411(S) |864(S) 
195(P) 1541(P 
10B(S) kl'6(S) 
42(P) Il486(r 


I623(S 

)I320(P 

740 (S 

) 660(P 


540(S 

961(P 

200 (S 

) 4I7(P 


H7(S)j 411 ! 
33I(P)| , 
35(S) 326 
I3I(P)I 



153 



TABLE 8. Organic carbon content of the Aber Wrac'h sediments, 
number of observations. 



(n) = 



SAMPLING 
STATION. 


n 


0C(l) m t s 


1 


5 


0.60 ± 0.15 (25 %) 


2 


4 


1.63 ± 0.65 (40 1) 


3 


3 


0.22 ± 0. 13 (59 1) 


4 


5 


1 .07 ± 0.32 (30 \) 


5 


5 


0.83 ± 0.15 (17 % ) 


6 


6 


1.16 i 0.88 (54 '.) 


7 


6 


1 .50 ± 1.14 (76 %) 


8 


6 


1.22 + 0.87 (71 %) 


9 


4 


0.90 ± 0.12 (14 %) 



In this discussion, three areas of Aber Wrac'h are described in 
terms of oil degradation:: (1) the mouth of the estuary (fine-grained 
sands, station 3), (2) the downstream part (stations 1, 2, 4, and 5), 
and (3) the upstream part (stations 6, 7, 8, and 9). The evolution of 
oil pollution in sediments from 1978 to 1981 for each station is given 
in Figure 8; the change in average oil concentrations for each of the 
three defined areas is given in the Table 9 and Figure 9. In March 
1978, 15 days after the AMOCO CADIZ wreck, concentrations ranged from 
773 ppm to 12,000 ppm. At the mouth of the Aber which is well exposed 
to high marine energy, hydrocarbon content dropped from 773 ppm in March 
1978 to 25 ppm in March 1981, illustrating a fairly rapid 
decontamination of these fine-grained sands. 

Since the sediments of the Aber Wrac'h are relatively homogeneous, 
the decontamination process is mainly related to the energy level of the 
zone. In the downstream part of the Aber, the sediments were more 
polluted in March 1978 (average about 5,000 ppm) than the sediments 
collected in the upstream part (average about 1,500 ppm). For the first 
39 months after the spill, a natural but slow decontamination was 
observed with some temporary increases in January 1980 (about 1,800 ppm) 
and March 1981 (about 780 ppm). In June 1981, the average residual oil 
content was about 600 ppm. In the upper part of the Aber, the sediments 
were initially less polluted, but since this is a low-energy area, a 
decrease in hydrocarbon content was not observed until January 1981. As 
had been observed in the downstream portions of the Aber, significant 
increases in hydrocarbon levels were observed during January 1980 in 
upstream areas. Since March 1981, oil levels have decreased; average 
residual oil concentrations were about 670 ppm. 

Three years after the wreck, the petroleum pollution of the Aber 
Wrac'h sediments seems to be relatively uniform. Figure 10 gives the 
observed decontamination rate of the sediments. At first approximation, 
station 3 (located at the mouth of the Aber) is well decontaminated (3% 
of the initial residual oil level observed in March 1978). However, 
sediments within Aber Wrac'h remain quite polluted with about 20 percent 
of the residual oil content still remaining in March 1978. 



154 



IBB 000,- HC CPPM] 



ib me. 



lass. 



100.. 



IB 



EvaurnoN des teneurs residueu.ee d hydrdcrrbures 

DHNS LE5 SEDIMENTS DE L RBER HRHOH 




12 



IB 21 



2H 27 



30 33 



36 



T CMDIS] 
t > 

42 



HS 



FIGURE 8. Evolution of residual oil pollution in Aber Wrac'h sediments, 



TABLE 9. Evolution of oil pollution (ppm) in the Aber Wrac'h sediments 
from 1978 to 1981. 



~~~^ (month: 


March 51 
) 1 'J 78 


May 5. 

1978 


Nov. 22, 
1978 


l-'chr .22, 
1979 


June 20, 
1979 


Oct. 22, 
1979 


Jan. 20 
1980 


June 
1980 


January 
1981 


March 16 
1981 


June 23 
1981 


LOCATIOV 


0.5 


1 .5 


8.25 


11.25 


IS. 25 


19.25 


19. 2S 


22.25 


34 


36 


39.25 


Month (st. 31 


T73 


1020 


148 


1 1 J 


74 


80 


- 


42 


- 


25 


- 


Downs t 1 l it'i ;i i t t 


"il)5l 


S914 


29 15 


1709 


1043 


109 3 


18 11 


1 158 


421 


783 


609 


1st. I , : , i . :. i 


■ loss 


15053 


1 1203 


16U2 


= 445 


1285 


= 531 


1595 


H 10 


!29S 


!290 


Upst r c.nn |i.. i i 


is:b 


1340 


857 


I72 1 


2149 


1SDS 


2512 


1390 


1 747 


901 


672 


(st. 0. ;,i,"i 


! 7 30 


•708 


•184 


= 578 


• 184b 


! 1 202 


!2I43 


1409 


H2S0 


!5S0 


!6S7 


All stations ol 
























the M.el ki.ii Mi 


3: 'jo 


3 300 


1886 


1718 


1590 


1329 


2161 


1274 


1084 


842 


640 


( st . 1 , J, 1. ,". 


• !<iM 


•3839 


•1358 


!5 n S 


•1377 


•847 


•1493 


= 489 


11 OSS 


•413 


1472 



155 



ibh era,. H< CPPM3 



10 2Z2 



IEZQ 



IBQ.. 



13 



EVtaajTION DES TENEURS RE5IDUELLES MOTENNES HYDRDOTRBURE5 
DRNS LES SEDIMENTS DE DIFFERENT5 SECTEURS DE L RBEH WRRCH 




5RHLE5 VH5ELK 

RHI2NT CST S.7iBi9: 

TDUTES 5TRTIDNS 
RVRL CST I.2.H.SJ 



SRBUES FINS 

EXBDUCHURE t5T 33 

T CMDI5J 



12 IS IB 21 2H 27 30 33 3B 39 H2 



FIGURE 9. Evolution of average residual oil pollution in sediments 
from the Aber Wrac'h. 



20 . 00 . . 



a aa 



TflUX DE DEaKTRMINfTrilW DES SEDIMENTS 
DC I RBEH HRRCH 




6 00 



12.00 



18. 019 2M.00 



3B.00 



jKJIBEH WRRCH 

ST I.2.M.S.B, 

7.8,1 3 



EMBOUOHURE C5T 3 3 

3 

I I 



.00 H2.C0 

T CMQI53 



FIGURE 10. The rate of oil decontamination in sediments from the Aber 
Wrac'h. 



156 



ACKNOWLEDGMENTS 

We would particularly like to thank Dr. Cabioch and personnel of 
the Station Biologique in Roscoff (France) for their cooperation and 
assistance throughout the work performed in the Bays of Morlaix and 
Lannion. The support of field scientists Serge Berne, Laurent 
d'Ozouville, and Anne Beslier is also gratefully acknowledged. This 
work was supported by the Ministere de l'Environnement et du Cadre de 
Vie (France) and the National Oceanic and Atmospheric Administration 
(U.S.A.) . 



REFERENCES CITED 

Beslier, A., 1981, Les hydrocarbures dans les sediments subtidaux au 
nord de la Bretagne: distribution et evolution: These de 3e 
cycle, Universite de Caen, 204 pp. 

Beslier, A., J. L. Berrien, L. Cabioch, J. L. d'Ouville, CI. Larsonneur, 
and L. Le Borgne, 1981, La pollution des sediments sublittoraux au 
nord de la Bretagne par les hydrocarbures de l"AMOCO CADIZ: dis- 
tribution et evolution: Cf. CNEXO (1981), pp. 95-106. 

Boehm, P. D., D. L. Fiest, and A. Elskus, 1981, Comparative weathering 
patterns of hydrocarbons from the AMOCO CADIZ oil spill observed at 
a variety of coastal environments: Cf . CNEXO (1981) , pp. 159-174. 

CNEXO, 1981, AMOCO CADIZ, fate and effects of the oil spill: Colloque 
International, Centre Oceanologique de Bretagne, Brest (France), 
882 pp. 

Ducreux, J. and M. Marchand, 1981, Evolution des hydrocarbures presents 
dans les sediments de 1 'Aber-Wrac'h d'avril 1978 a juin 1979: Cf. 
CNEXO, pp. 175-216. 

Marchand, M. , 1981, AMOCO CADIZ, bilan du colloque sur les consequences 
d'une pollution accidentelle par hydrocarbures, Brest, november 
1979: Publ. CNEXO, Rapp. Scient. et Techn. n° 44, 86 pp. 

Marchand, M. and M. P. Caprais, 1981, Suivi de la pollution de l'AMOCO 
CADIZ dans l'eau de mer et les sediments: Cf. CNEXO, pp. 23-54. 

Marchand, M. and L. d'Ozouville, 1981, Etude de la pollution par les hy- 
drocarbures de l'AMOCO CADIZ des sediments des baies de Morlaix et 
de Lannion: Rapport de Contrat CNEXO/NOAA, Centre Oceanologique de 
Bretagne, Brest (France), (in press). 

Marchand, M. and J. Roucache, 1981, Criteres de pollution par 
hydrocarbures dans les sediments marins. Etude appliquee a la 
pollution du BOHLEN: Oceanologica Acta 4(2), pp. 171-181, 



157 



AMOCO CADIZ POLLUTANTS IN ANAEROBIC SEDIMENTS: 
FATE AND EFFECTS ON ANAEROBIC PROCESSES 

by 

1 112 

David M. Ward , Michael R. Winfrey , Eric Beck and Paul Boehm 

1) Department of Microbiology, Montana State University, Bozeman, 
Montana 59717 

2) Energy Resources Company, Inc., Cambridge, Massachusetts 02138 



INTRODUCTION 

It was estimated that much of the oil spilled after the wreck of 
the AMOCO CADIZ impacted intertidal and subtidal sediments (Hann, et 
al, 1978; Gundlach and Hayes, 1978). Considerable differences exist 
between sediment and aquatic environments which could have dramatic 
effects on the persistence of spilled oil and its effects on the native 
biology of coastal environments. Recent investigations have shown that 
intertidal and subtidal sediments are anaerobic except in the initial 
few millimeters near the surface (S^rensen, et al, 1979; Revsbech, et 
al, 1980a, b) . Since oxygen is known to be of extreme importance in 
the microbial biodegradation of hydrocarbons (Atlas, 1981; Hambrick, et 
al, 1980; DeLuane, et al, 1981; Ward and Brock, 1978) it is likely that 
the persistence of hydrocarbons would be much greater in anoxic sedi- 
ments. This could create a source of relatively unweathered petroleum 
for secondary pollution events. One of the major objectives of this 
study was to investigate the extent of pollution by AMOCO CADIZ oil in 
anaerobic coastal sediments. Evidence for weathering and potential 
biodegradation of sediment hydrocarbons under aerobic and anaerobic 
conditions was also obtained in chemical and microbiological studies. 

Sediments are also important sites where extensive mineralization 
of organic matter and recycling of nutrients occurs (Fenchel and J#r- 
gensen, 1977). The effect of oil on sediment microorganisms and pro- 
cesses has been examined in some studies (Walker, et al, 1975; Knowles 
and Wishart, 1977) but only a few studies have examined the effects on 
mineralization (Griffiths, et al, 1981, 1981 (in press)). Because of 
the extreme thinness of the oxygenated zones of coastal sediments, an- 
aerobic processes are important in mineralization and nutrient recycl- 
ing (S^rensen, et al, 1979). The effects of oil on anaerobic processes 
have not been studied . Many studies on sediment chemistry and microbio- 
logy support the model for anaerobic microbial food chains in marine 
sediments presented in Figure 1 (see Mah, et al, 1977; Fenchel and J^r- 
gensen, 1977; Rheeburg and Heggie, 1977; Bryant, 1976). Within anaero- 
bic zones polymeric organic matter is fermented principally to H , CO 
and acetic acid. Acetate and H„ are the main energy sources for spec- 
ialized anaerobic bacteria which terminate the food chain. The activi- 
ty of these terminal groups is thought to be important in influencing 
fermenting bacteria to produce mainly acetate, H„ and CO (Bryant, 
1976) . The importance of these energy sources in marine sediments has 

159 



POLYMERIC ORGANIC MATTER 



FERMENTING 



BACTERIA 



C °2 + H 2 + ACETATE 



METHANE-PRODUCING 
BACTERIA 





SULFATE-REDUCING 
BACTERIA 




Figure 1. Simple model for anaerobic microbial food chains in marine 
sediments. The model does not include minor electron sink 
fermentation products or other possible anaerobic groups such 
as denitrifying bacteria. The asterisk indicates the major 
product from the methyl position of acetate. 



only been confirmed in this and other recent studies (Winfrey and Ward, 
submitted; S^rensen, et al, 1981; Banat and Nedwell, personal communi- 
cation). Sulfate-reducing and methane-producing bacteria share the 
potential to utilize these fermentation products and may compete in 
marine sediments. Detailed investigations to characterize anaerobic 
processes in Brittany sediments were made as a part of this study, but 
discussion here is beyond the scope of this report. In summary, meth- 
anogenesis is only significant in the competition for acetate and H~ in 
sediments where sulfate is depleted (e.g., deep subtidal sediments, 
Winfrey, et al, in press). In intertidal sediments where sulfate is 
high at all depths (see below), methanogenic bacteria may be restricted 



160 



to energy sources other than acetate or HL (such as methylamines) , and 
sulfate reduction dominates as the significant terminal process (Win- 
frey and Ward, submitted). As another major objective of this study we 
examined terminal processes of the anaerobic food chain, which should 
indicate the activity of the overall food chain, for evidence of 
changes due to AMOCO CADIZ oiling. The processes investigated were 
those which dominated the food chains, principally sulfate reduction 
and acetate metabolism. 



METHODS 



Location of Sampling Sites 

Sites were selected to represent beach, estuary and salt marsh 
sediments in the lower intertidal region which were significantly oiled 
by AMOCO CADIZ pollutants. Similar sites in areas unoiled or lightly 
polluted were selected as controls. Locations are shown in Figure 2. 
Observations on the chronology of oil movements were used to determine 
the extent of oil impact and times at which oiling first occurred 
(Centre National pour 1 'Exploitation des Oceans, 1979; Gundlach and 
Hayes, 1978). The oiled beach site was between stations B and C at 
AMC-4 (Gundlach and Hayes, 1978). This site was opposite the wreck and 
was heavily oiled immediately after the spill. The control beach site 
was 100 m east of the west access to the beach at Trez-hir. This beach 
faces the Bay of Brest and was not reported to have been oiled. The 
oiled estuary site was a mudflat at Aber Wrac'h, 200 m south of the 
stone wall at EPA-7 (Calder, et al., 1978). AMOCO CADIZ oil was de- 
tected in this area in medium thickness two days after the oil spill. 
The control estuary site was a mudflat on the south bank of Aber Ildut 
approximately 3 km west of Breles. Oiling at this site was prevented 
by two booms extended across the mouth of the Aber. The oiled marsh 
site was an intertidal mudflat in lie Grande near AMC-18 (Gundlach and 
Hayes, 1978). Thick accumulations of AMOCO CADIZ oil reached this site 
by 'the eighth day following the spill. The control marsh was a natural 
mudflat in the lie Grande marsh, just south of the main intertidal 
channel. A barricade at the bridge adjoining east and west marsh areas 
prevented oiling at this site. 



Sample Collection and Processing 

Sediment cores were collected with hand- pushed plexiglass tubes 
(60 cm x 37 mm ID), stoppered, and transferred to the lab in an upright 
position. Cores for sediment hydrocarbon analysis were kept frozen 
until processing. Processing of samples for biological activities was 
done at the Centre Oceanologique de Bretagne in Brest or at the Station 
Biologique at Roscoff within 8 h after collection. All manipulations 
for analysis of biological activity were carried out using strict an- 

161 



® 



' 



AMOCO CAQiZ 



A8ER .^""V^. 







"V 



r^\- 







U 



BE" 'LOUT 






./ 






U? 




Figure 2. Locations of sampling sites. 



aerobic techniques designed for cultivation of bacteria with extreme 
sensitivity to oxygen (Hungate, 1969). Cores were sectioned into de- 
sired intervals and subcores removed by a No. 4 cork-^borer or by a 3 ml 
syringe with the end of the barrel cut off (50.3 mm ). The 0-3 cm in- 
terval was used for all the oil and mousse addition experiments. For 
these experiments an anoxic slurry was made by mixing the core section 
with 20% (V/V) anoxic artifical seawater (ASW, Burkholder, 1963). In 
experiments on hydrocarbon metabolism slurries of other depth intervals 
were made in the same way. Subsamples (2.0-2.5 ml) from core sections 
or slurries were transferred to 2 dram glass vials (Acme Vial and Glass 
Co.) and sealed under a stream of helium. The helium was passed over 
heated copper filings to remove any traces of oxygen. Vials were 
sealed with 00 butyl rubber stoppers (A.H. Thomas). Unless noted be- 
low, all isotope additions (1.0 ml) were taken from sterile anoxic 
stock solutions with a 1 ml helium flushed glass syringe (Glaspak) . 
Mousse, oil and hydrocarbon additions were added to vials containing 
sediment under a flow of helium gas using a 1 ml pipet 12 hours before 
microbial activities were assayed. Benzene and toluene were added with 
a 5 pi syringe (Hamilton). 



Measurement of Microbial Activities 

All incubations were done at ambient temperatures (20-24°C). Com- 
parisons between different samples were made by a two sample t test, 
using the AN0V1 program of MSUSTAT (Lund, 1979). 



162 



Sulfate Reduction 

Sulfate reduction assays were set up using a modification of the 
technique of Ivanov^ (1964) . Each vial of sediment received approxi- 
mately 1 pCi of Na„ SO, in 1 ml of anoxic ASW. Samples were mixed and 
incubated for 2.0 n. The reaction was stopped by the addition of 0.5 
ml of 2% zinc acetate followed by 0.2 ml of formalin. Samples were 
assayed and rates determined in the Montana State University lab as 
described by J^rgensen (1978). H„ S was distilled to traps containing 
2% zinc acetate. Radioactivity was determined by counting the zinc 
acetate trap (5 ml) in 10 ml Aquasol (New England Nuclear) on a Beckman 
LS-100C liquid scintillation counter. Correction for quenching was by 
the channels ratio method. 

Methane Production 

Methane production was measured by quantifying the increase in 
methane in the head-space of vials containing sediment. A 0.2 ml gas- 
eous subsample was removed at desired intervals and analyzed by flame 
ionization gas chromatography (see below). 

Acetate Metabolism 

..Acetate metabolism was measured by adding approximately 0.5 (JCi of 
[2- C]-acetate in 1.0 ml of sterile anoxic sulfate-free ASW. Samples 
were mixed and incubated for 2.0 h unless otherwise stated... The reac- 
tion was stopped by the addition of 0.2 ml formalin. C0„ and/or 
CH, were measured in samples of the gas headspace (see below). 

Hydrocarbon Metabolism 

All radiolabelled hydrocarbons except benzene and toluene were di- 
luted in benzene to the desired activity. The radioisotopes were added 
to vials and the benzene allowed to evaporate completely before addi- 
tion of sediment and anaerobic tubing as described above. Anoxic ASW 
(1.0 ml) was added to each sample to mix sediment and radioisotopes. 
Radiolabelled benzene and toluene were dissolved in anoxic ASW and 
added (1.0 ml) after anoxic tubing of sediment. When indicated, sam- 
ples were incubated in darkness by wrapping with aluminum foil or 
electricians tape. In one experiment samples contained in anaerobi- 
cally sealed tubes were incubated within an anaerobic chamber (Gaspak) 
with a H„ "\/C0 atmosphere. During long term incubations gaseous meta- 
bolities ( C0„ and/or CH.) were quantified in samples of the gas 
headspace as described below. After incubation was completed, samples 
were poisoned by addition of 0.5 ml 10% formalin. Carbon dioxide was 
reabsorbed by addition of 2 ml 2N NaOH. The sediment was extracted 
four times by vortex mixing with 6 ml methylene chloride: methanol 
(9:1) followed by centrifugation to break the emulsion. Solvent frac- 
tions were removed from beneath the aqueous phase and pooled together 
with three 6 ml rinses of the original sample vial. Anhydrous sodium 
sulfate was added to dry the sample. The extract was concentrated to 
0.1 ml by evaporation and the volume increased by addition of 0.7 ml of 
hexane. This sample was separated into saturate (f,), aromatic (f ? ) 

163 



and methanolic (f~) fractions by silica gel chromatography as described 
for oil samples Below. Each solvent fraction was concentrated by ro- 
tary evaporation to 4 ml and radioactivity of a portion of the extract 
was., .determined in AquasoL.as described above. Using these methods 
[1- C] -hexadecane and [1- C] -heptaderene standards were recovered in 
the f 1 fraction, whereas [1(4, 5, 8)- C] -naphthalene was recovered in 
the fl fraction. CO was transferred from the extracted sediment 
after acidification ana distillation to a C0„ absorbant trap (Carbo- 
sorb, Packard). This trap was combined with Aquasol and radioactivity 
determined as described above. 



Gas Measurements 

Gas subsamples (0.2 to 1.0 ml) were removed from the headspace of 
incubation vials using a helium flushed 1 ml glass syringe (Glaspak) 
fitted with a Mininert pressure-lock syringe valve (Supelco) . CH, 
and C0„ were measured by gas chromatography- gas proportional count- 
ing using the method of Nelson and Zeikus (1974) as modified by Ward 
and Olson (1980). This method ensured the specific detection of these 
gaseous metabolites. All numerical results were based on amounts 
clearly above detection limits, and quantifiable by integration using a 
Spectra-Physics Minigrator. C0„ values were corrected for CO^ solu- 
bility and bicarbonate equilibrium as described by Stainton "t 1973) . 
Methane concentrations were quantified on a Varian 3700 flame ioniza- 
tion gas chromotograph as described by Ward and Olson (1980). All 
values for gas analyses are reported on a per vial basis. 



Chemical Analysis of Oils 

Similar methods were used for the analysis of sediment hydrocar- 
bons (ERCO) or oils (MSU) although the specific details differed. 
Sediment hydrocarbon samples were solvent extracted and fractionated 
according to an analytical scheme patterned after that of Brown et al 
(1980). Hydrocarbons were separated from methanol-dried samples by 
high-energy shaking with methylene chloride:methanol (9:1), fraction- 
ated into saturate, aromatic/unsaturate and methanolic fractions by 
alumina/silica gel column chromatography, and analysed by gas chroma- 
tography, mass spectrometry and/or mass f ragmentography as described by 
Boehm, et al (1981). 

AMOCO CADIZ mousse, fresh or evaporated crude oil, and extracts 
from ll+ C-hydrocarbon experiments (see above) were analyzed as follows. 
Each sample (a 25 (Jl aliquot of each oil sample diluted in 0.5 ml of 
hexane, or extracts described above) was loaded onto a glass column (1 
cm ID x 20 cm long) packed with 40-140 mesh silica gel (Baker Chemical 
Co.). Saturate components (f,) were removed from the column by eluting 
with 200 ml of hexane. The aromatic fraction (f ) was then eluted with 
200 ml of a solution of hexane and methylene chloride (70/30 V/V) . The 
methanolic fraction (f ) was then eluted with 150 ml of methanol. Each 
fraction was concentrated to 3-4 ml by flash evaporation and further 

164 



concentrated to less than 1 ml under a stream of nitrogen. The volume 
of each fraction was adjusted to one ml with the appropriate solvent. 
A 0.2 (Jl subsample was injected into a Varian 3700 flame ionization gas 
chromatograph equipped with a 30 m glass WCOT column packed with SE-54 
(Supelco) . Operating conditions were as follows: column temperature 
programmed from 60 C to 260 C at 3 C/min with a 30 min hold at 260 C; 
injection temperature: 250 C; detector temperature 250 C; carrier gas: 
1 ml helium/min with a helium make-up gas of 29 ml/min. Results were 
recorded on a Spectra-Physics model 4100 recording integrator. Hydro- 
carbons labelled in Figure 9 were identified by comparison of retention 
times to those of pure hydrocarbon standards. 



Sediment Chemistry 

Eh 

Duplicate sediment cores for Eh measurements were collected using 
a plexiglass tube (30 cm x 25 mm ID) which had been split lengthwise 
and taped together. Upon returning to the laboratory, one half of the 
core liner was removed, and fresh sediment exposed 1 cm at a time by 
slicing the core lengthwise with a spatula. Eh measurements were taken 
by pressing a combination platinum electrode (Orion) into the freshly 
exposed sediment surface. All Eh values are reported relative to the 
normal H„ electrode. 

pH 

pH was determined using a VWR pH Master pH meter and glass com- 
bination electrode. 

Interstitial Water 

Sediment porewater was obtained using the porewater squeezer of 
Kalil (1974). After appropriate dilutions were made, sulfate was meas- 
ured by the turbidometric method of Tabatabai (1974) and chloride was 
measured by silver nitrate titration (Am. Pub. Health Assoc, 1976). 

Methane 

Dissolved methane was quantified by killing a 2 ml subcore in a 
sealed vial by the addition of 0.5 ml of formalin and mixing on a vor- 
tex mixer to strip the dissolved methane into the headspace. A gas 
subsample was then analyzed by flame ionization gas chromatography as 
described above. 



Radioisotopes, Chemicals, and Oils 

The following radioactive chemicals were used (radiochemical pur- 
ity in parentheses): Na 2 S0 4 , 738^01/1^11016 (on 3/5/79), Na-[2- C]- 
acetate, 44 mCi/mmole, and [ring-1- C]-toluene, 3.4-5.2 mCi/mmole (97- 

165 



14 
99%) from New England Nuclear; n-[l- C] -hexadecane , 54 mCi/mmole (97- 

99%), [1(4, 5, 8)- C] -naphthalene, 5 mCi/mmole (97-98%), [U- C]-ben- 

zene, 101 mCi/mmole (98-59%), [7, 10- C]-benzo(a]pyrene, 60.7 mCi/m 

mole, (99%), and [methyl- C]-toluene, 30 mCi/mmole (96-99%) from Awer- 

sham Corp.; n-[l- C] -heptadecane , 16 mCi/mmole (>99%), and [1- C]- 

heptadecene, 18.5 mCi/mmole (97%) from ICN. 

AMOCO CADIZ mousse was obtained from the NOAA National Analytical 
Facility and was collected at Ploumanach on April 30, 1978 (44 days 
after the spill). Light Arabian crude oil (SX//0308) was obtained from 
Exxon Corp., Baytown, Texas. The crude oil was weathered by evapora- 
tion at 25 C for 8 and 48 h. All oil samples were stored at 4 C until 
used. 



RESULTS 



Physical-Chemical Comparison of Sites 

Beach cores consisted of medium grained sand, while estuary and 
marsh cores consisted of fine grained silt and clay. It was possible 
to determine Eh profile for muddy sediments (Fig. 3). In all sediments 



Eh (mv) 
+ IOO + 200 +300 -100 




SALT MARSH MUDFLATS 



+ 100 +200 +300 

- 1 - -£r-' ' 



/ 



\ 



« V AW 



A 



AI 



/ 



/ 

\ 



ABER MUDFLATS 



Figure 3. Eh profiles in muddy sediments. Bars indicate the range of 
measurements on duplicate cores. pH increased with depth 
from 7.5 to 8.2 in He Grande, from 6.7 to 7.2 in Aber lldut, 
from 5.9 to 7.5 in Aber Wrac'h and from 7.0 to 8.1 in the lie 
Grande oiled site. 



conditions became more reducing with depth. The steepest Eh profile 
was observed in the He Grande oil site where a brown layer approxi- 
mately 2 mm thick covered black sediment. Marsh mudflat sediments 



166 



showed steeper Eh profiles than estuarine sediments and oiled sediments 
were more reducing and showed steeper Eh profiles than unoiled sedi- 
ments of the same type. The large Eh change with depth (300mv over 
1 cm (lie Grande oiled site) or 2 cm (Aber Wrac'h) suggested that sedi- 
ments below these depths are likely anoxic. 

Chloride (data not presented) was relatively constant at all depths 
in all sites and was near seawater chloride levels (20,000 mg/liter). 
The concentrations of dissolved sulfate and methane with depth in each 
site are reported in Table 1. No major differences in sulfate concen- 
tration with depth or between cores were observed, _and levels were 
similar to seawater values (approximately 800 mgSO, -S/l ). Methane 

TABLE 1. Sediment Chemistry 3 

SULFATE CHEMISTRY** 

DEPTH AMC 4 TREZ-HIR ABER WRAC'H ABER ILDUT ILE GRANDE ILE GRANDE 
(cm) (oiled) (control) 



0-5 


720 


720 


860 


840 


840 


760 


5-10 


850 


770 


900 


830 


790 


800 


10-15 


820 


820 


870 


970 


750 


760 


15-20 


1070 


1190 


820 


810 


740 


790 


20-25 


-- 


-- 


860 


920 


800 


710 



METHANE CHEMISTRY 



0-5 


0.17 


0.16 


0.74 


1.57 


3.36 


0.24 


5-10 


0.52 


0.84 


0.80 


0.89 


2.89 


1.09 


10-15 


0.64 


0.67 


0.79 


0.66 


3.34 


0.26 


15-20 


— 


— 


0.99 


0.93 


4.26 


0.35 


20-25 


-- 


-- 


0.50 


0.81 


4.36 


0.36 



Sediments collected in March 1979 



Results expressed in pg SO, -S/ml porewater 

p 

Results expressed in (jmoles CH./l sediment 

167 



concentrations were extremely low (less than 5 (Jmoles/1) and relatively 
constant with depth. Methane concentrations were significantly higher 
at the lie Grande oiled site (p < .001). 



Sediment Hydrocarbons 

Sediments collected during December 1978 and March 1979 were ana- 
lyzed for hydrocarbon content (Table 2) and type (Figs. 4 and 5) . Sur- 
face sediments (0-5 cm) at all sites oiled with AMOCO CADIZ oil exhi- 
bited a composition indicative of highly weathered oil residues. The 
saturate fractions were comprised of a degraded hydrocarbon assemblage 
with greater degradation in estuary and marsh mudflat samples than in 
the beach sample as evidenced by the relative dominance of the branched 
isoprenoid hydrocarbons (Fig. 4). Residual alkylated phenanthrenes , 
and dibenzothiophenes in the aromatic/unsaturate fractions (Fig. 5) 
also indicated the presence of weathered petroleum. All samples known 
to be impacted by AMOCO CADIZ oil exhibited a characteristic unresolved 
complex mixture (UCM) in both saturate and aromatic/unsaturate frac- 
tions indicative of weathered petroleum (Farrington and Meyers, 1975). 

Qualitative and quantitative differences existed between oiled and 
unoiled control sediments in the 0-5 cm depth interval. Hydrocarbon 
content was always higher in oiled sediments (Table 2) . The control 
estuary sediment exhibited a small UCM and hydrocarbons indicative of 
biogenic origin in the saturate (odd chain alkanes n - C to n-C_ ) and 
aromatic/saturate (polyolef inic material) fractions. Tne control marsh 
sediment exhibited a mixture of hydrocarbons of biogenic (odd-chain al- 
kanes n-C.,. to n-C„ ) and petroleum (UCM) origin, with low concentra- 
tions of residual aromatic/unsaturate hydrocarbons. The control beach 
sediment exhibited a n-alkane series (n-C ,. to n-C„~) and UCM in the 
saturate fraction, and polynuclear aromatic components originating from 
combustion of fossil fuel (eg. , nonalkylated 3-5 ringed polynuclear 
aromatics) (Youngblood and Blumer, 1975). 

The types and amounts of hydrocarbons were consistent with the 
known degree of impact from the AMOCO CADIZ oil spill. It is clear 
that in control beach and marsh sediments impact by hydrocarbons of 
petroleum or other anthropogenic sources had occurred. 

Evidence for degraded Amoco Cadiz oil at various sediment depths 
is summarized in Table 2. At the beach station AMC-4 , AMOCO CADIZ oil 
was evident in the hydrocarbon assemblage down to the 10-15 cm interval 
in a sample collected in December 1978, and to the 15-20 cm interval in 
a sample collected in March 1979. At Aber Wrac'h there was evidence of 
AMOCO CADIZ oil to the 10-15 cm interval at both collection dates. The 
amount of oil decreased with depth as evidenced by the total hydrocar- 
bon concentration and the increasing contribution of native sediment 
hydrocarbons (e.g., plant derived saturate and aromatic/saturate com- 
pounds) which dominated in the deepest layers as in the entire Aber 
Ildut core (see Figs. 4, 5). Similar results were found at the lie 
Grande oiled site where AMOCO CADIZ oil was detected in the 5-10 cm 
layer on both sampling dates and biogenic compounds dominated deeper 
layers. 168 



TABLE 2. Preliminary Results of Total Hydrocarbon Levels in Brittany 
Sediments (AC=AMOCO CADIZ Oil Indicated by GC-MS Data) 



Sediment Type 


Depth 
Interval 


Tot; 


»1 


Hydrocarbons 


(mr/r) 




0: 


Lied 




Control 




(cm) 


12/78 




3/79 


3/79 


Beaches 




AMC- 


-4 




Trez-Hir 




0-5 


295 AC 




217 


AC 


110 




5-10 


158 AC 




181 


AC 


46 




10-15 


244 AC 




162 


AC 


130 




15-20 


72 




128 


AC 






20-22 


123 










Abers 




Aber 


W 


rac'h 




Aber Ildut 




0-5 


977 AC 




1095 


AC 


690 




5-10 


590 AC 




630 


AC 


530 




10-15 


47 AC 




307 


AC 


305 




15-20 


80 




118 




204 




20-25 


33 




103 




115 




25-30 


25 








346 




30-35 


45 










Salt Marshes 




He 


Grande 




He Grande 




0-5 


1137 AC 




863 


AC 


465 




5-10 


144 AC 




439 


AC 


365 




10-15 


28 




134 




217 




15-20 


32 




220 




154 




20-25 






74 




54 



Evidence for Weathering of Sediment Hydrocarbons 

It was evident that oil was present at depths where extremely re- 
ducing conditions indicated the lack of oxygen (Aber Wrac'h and the He 
Grande oiled site), as well as in surface sediments which were more 
likely exposed to oxygen. This provided an opportunity to compare 
weathering patterns in sediments with markedly different exposure to 
oxygen. Since the actual amount of oil could vary between sites, evi- 
dence of weathering was sought by comparing the relative amounts of 
hydrocarbons extracted from single samples known to be polluted with 
AMOCO CADIZ oil. Because of the rapid and extensive biodegradation 
which apparently followed the AMOCO CADIZ spill (Atlas, et al, 1981; 
Ward et al, 1980) the comparison of n-alkanes to the more recalcitrant 
isoprenoid alkanes of similar volatility was not possible as an index 
of biodegradation. By the first sampling date (December 1978), n-C17/ 

169 



(A) Oiled Estuary Mudtiat 




cms "■ ■ i ■ 

l'M> Ph.linr 

I i lnli«r\JI 5tjr«lJ>(l 

>>iolv«d 

. . " .■ 



(B) Control Estuary Mudtiat 



,ilUi. 



jw 



li 



i i 



iCI O.led Sail Marsh Muddat 



ID) Control Salt Marsh Mutlflat 




I. I .. 



> 



A 



IE) O'led Beach 



(F/ Control Beach 




XU> \ 



i 



3 r^iMh , 



FIGURE 4. Gas chromatograms of saturate fraction of hydrocarbons ex- 
tracted from Brittany sediments collected in March 1979 (0-5 
cm depth interval) . 



(A) Oiled Estuary Mudtlat 



r«h«nan|H.en<M A 




IB! Control Estuary Murlllal 




ICI OiImI Salt Marsh Mudflat 



;D' Control Salt Marsh Mu 




jlfjAl^M., 



(El Oiled Beach 



AihvlJKnl 

Pflf n.,.. ■ 

* O iMntdin ■ n-r - 




iF) Control Beach 



ilillW 



CnmiiuMi 



H, 



-4. 



FIGURE 5. Gas chromatograms of aromatic/unsaturate fraction of hydrocar- 
bons extracted from Brittany sediments collected in March 1979 
(0-5 cm depth interval) . 



170 



pristane and n-C18/phytane which were 3.3 and 2.8 in the reference 
mousse, were 0.07-0.58 and 0.024-0.36, respectively. Becase of the 
relative persistence of aromatic hydrocarbons (Atlas, et al, 1981; Ward 
et al, 1980), alkylated naphthalenes, phenanthrenes and dibenzothio- 
phenes remained in Brittany sediments at levels sufficient to study 
weathering patterns in a long term time/depth series. The loss of 
these compounds relative to the more persistant C„-alkylated deriva- 
tives of dibenzothiophene (CL-DBT) is thought to be an index of weath- 
ering (Grahl-Nielsen, et al, 1978). There is no published evidence 
that changes in aromatic compounds relative to C„-DBT are due to bio- 
degradation, but these compounds are subject to microbial attack (Atlas, 
1981). 

The ratios of aromatic compounds to CL-DBT showed different 
changes with time depending on type of sediment and sediment depth 
(Table 3). In the AMC-4 0-5 cm interval there was a systematic de- 
crease in nearly all ratios from December 1978 to March 1979 to No- 
vember 1979. In muddy sediments decreases were less rapid and exten- 
sive. By March 1979, C - and C,- naphthalenes, C„- and C,- phenan- 
threnes and C-DBT showed: relative decreases in the Aber Wrac'h 0-5 cm 
interval. An Aber Wrac'h core collected in November 1979 was sub- 
divided at one centimeter intervals at the depths of greatest change in 
Eh. In the 1-2, 2-3, and 3-4 cm intervals naphthalenes were "almost 
entirely depleted. Relative decreases in all except C - and C,- phen- 
anthrenes were noted compared to earlier samples, with no great differ- 
ences among these depth intervals. Phenanthrenes were enriched rela- 
tive to C-DBT by May 1980 in the 0-3 cm interval. Ratios of aromatic 
hydrocarbons to C.-DBT were generally greater in deeper layers (5-10, 
10-15 cm) than in surface layers on any given date. Nevertheless, the 
data suggest that decreases in naphthalenes and DBT's occurred in the 
5-10 cm interval in the one year between December 1978 and November 
1979, despite the relative constancy of C,-DBT over the time period. 
Results for lie Grande were similar to those for Aber Wrac'h but the 
relative amounts of most components were greater. Between December 
1978 and March 1979, there was a relative enrichment of all components 
except C, -naphthalene. In March 1979, ratios were higher at 5-10 cm 
than at 0-5 cm. Finer resolution around the depths of greatest Eh 
change was attempted on samples collected in May 1980. There was evi- 
dence of decreases in naphthalenes compared to earlier samples at all 
depths, even though the concentration of C.-DBT was very high in all 
samples. Relative decreases in C -phenanthrenes and DBT's were noted 
in the 0-2 mm and 2-10 mm intervals. Except for C, -phenanthrenes , ra- 
tios were always higher in the 3-4 cm interval. 



Hydrocarbon Biodegradation 

14 
In initial experiments, various C-labelled aliphatic or aromatic 

hydrocarbons were incubated with surface sediments under aerobic condi- 
tions, or with subsurface sediments under conditions designed to pre- 
vent the exposure of obligately anaerobic bacteria to oxygen. The juc- 
cess of anaerobic methods was evidenced by the reduction of SO, to 

171 



TABLE 3. Aromatic Hydrocarbons in Brittany Sediments Oiled by the 
Spill 





STATION 




RATIOS 


TOC 3 - 


-DIBENZOTHIOPHENES 




ng/g 
C -DBT 


DATE DEPTH 


NAPTHTHALENES 
C 2 C 3 C 4 


PHENANTHRENES 


DBT 


'S 




C l 


C 2 


C 3 


C 4 


C l 


C 2 




AMC-4 






















12/78 0-5cm 


.17 


.52 


.67 


.28 


.29 


.48 


.36 


.35 


1.08 


785 


3/79 0-5cm 


.02 


.21 


.38 


.04 


.23 


.30 


.17 


.32 


.97 


735 


11/79 0-5cm 


.01 


.01 


.01 


.10 


.20 


.28 


.08 


.01 


.38 


400 


ABER WRAC'H 






















12/78 0-5cm 


.03 


.19 


.29 


.05 


.16 


.35 


.18 


.16 


.84 


3,976 


5-10cm 


.02 


.51 


.54 


.16 


.34 


.39 


.24 


.35 


1.14 


811 


10-15cm 


.05 


.17 


.20 


.28 


.42 


.39 


.36 


.19 


.90 


275 


3/79 0-5cm 


.03 


.18 


.18 


.13 


.18 


.32 


.08 


.01 


.92 


1,598 


5-10cm 


.06 


.22 


.51 


.22 


.33 


.42 


.12 


.16 


1.64 


831 




.04 


.18 


.32 


.21 


.34 


.31 


.24 


.19 


1.01 


492 


11/79 l-2cm 











.10 


.08 


.33 


.28 


.01 


.63 


2,400 


2-3cm 








.01 


.05 


.10 


.32 


.23 


.01 


.59 


2,200 


3-4cm 











.02 


.05 


.05 


.26 





.44 


1,800 


5-10cm 





.02 


.09 


.14 


.23 


.59 


.53 


.06 


0.60 


860 


5/80 0-3cm 








.04 


.13 


.20 


.76 


1.00 


.04 


.42 


1,700 


ILE GRANDE OILED 




















12/78 0-5cm 


.04 


.22 


.32 


.13 


.22 


.28 


.22 


.16 


.91 


2,809 


3/79 0-5cm 


.10 


.36 


.37 


.24 


.38 


.32 


.22 


.54 


1.37 


2,666 


5-10cm 


.34 


.88 


.76 


.46 


.42 


.46 


.27 


.63 


1.44 


745 


5/80 0-2mm 





.01 





.05 


.24 


.48 


.56. 


.09 


.63 


16,000 


2-10mm 








.05 


.06 


.19 


.42 


.45 


.07 


.62 


12,000 


3-4cm 


.007 


.07 


.18 


.09 


.28 


.52 


.35 


.15 


.82 


82,000 



172 



35 14 

H 9 S, and in some cases the generation of CH, within two hours of 

incubation, (Winfrey and Ward, submitted). In long-term incubations no 
C0„ or CH, was detected in fprmalin-killed controls. In most cases 
significant amounts of C0„ + CH, were detected in vials incubated 
aerobically (Table 4). Anaerobic incubation severely reduced the 
amount of radiolabelled gases formed. However, small amounts of these 
metabolites were formed from n-hexadecane , n-heptadecane, heptadecene, 
ring or methyl labelled toluene, and benzene after lengthy anaerobic 
incubation. The amount of gaseous metabolites formed did not exceed 
5% of the added radiolabel and reproducibility was poor. Repeated ef- 
forts by two individuals experienced in cultivation of methanogenic 
bacteria led to the same observations. Additions of FeCl. or KNO (1 
ml of 0.5% (w/v) solutions in anoxic ASW replaced the 1 mi addition of 
anoxic ASW) did not stimulate the formation of C0„ and CH, from 
n-hexadecane or heptadecene in Aber Wrac'h 5-10 cm sediment. 

The possibility of initial accidental exposure to oxygen during 
tubing of samples was investigated by late addition of C-toluene 
which was soluble in water and could be added as an anoxic solution 
well after any oxygen initially present should have been consumed dur- 
ing dark incubation. Revsbech, et al, (1980b) have shown that oxygen 
consumption in intertidal sediments occurs in a matter of minutes fol- 
lowing, darkening to eliminate photosynthesis... As shown in Figure 6, 
ring- C-toluene was readily metabolized to CC> when added either at 
the time of anaerobic tubing or 38 hours after dark anaerobic incuba- 
tion began. Similar results were found for [methyl- C]-toluene. 

It was conceivable that the radiolabelled gases might have been 
produced from contaminants rather than from the hydrocarbons them- 
selves. When an attempt was made tcL recover the added C in, long-term 
radiolabelling experiments with [1- C] -heptadecane and Jl- C] -hepta- 
decene, it was noted that the total amount of CO + CH, produced 
during anaerobic incubations was similar to the level of impurities 
measured in C-labelled hydrocarbons recovered from formalin controls 
or from unpurified stocks of added radioisotopes (Table 5). Stock 
solutions were chromatographically separated into f , f„ ^nd f„ com- 
ponents which were then tested separately as sources of C-gases in 
dark anaerobic incubations with anaerobic sediments. The results of 
such experiments are presented in Eigure 7. The repurified f frac- 
tions of [1- C] hexadecane and [ 1- , C] -heptadecane were clearly sig- 
nificant sources for production of CO during dark anaerobic incuba- 
tions with a slurry of lie Grande oiled 3-6 cm sediment. Increases in 
CO with time following a lag of 5-15 days also suggested that oxi- 
dation did not result from any oxygen which might have been introduced 
accidentally during tubing. Similar results were observed with repuri- 
fied f of [1- C] -heptadecene. 

A final control was run to test the possibility that slow diffu- 
sion of oxygen through the vessels containing incubating samples could 
account for the obsexved metabolism. Darle .anaerobic incubations of 
repurified f of [1- C] -hexadecane and [1- C] -heptadecane were car- 
ried out with a slurry of mud from the 3-6 cm interval of Aber Wrac'h 
sediment. The individual vials were incubated inside an anaerobic 

173 



TABLE 4. 11 *C0 2 + 1<t CHi l produced on 223 Day Incubation of Oiled Sediments 
with ll+ C-Hydrocarbons (12/78). 















% OF ADDED 


14 c a 






HYDROCARBON 


ABER WRAC 

0-5cm 5-10cm 

AEROBIC ANOXIC 


H 

10-15cm 
ANOXIC 


1LE 
0-2cm 
AEROBIC 


GRANDE 
2-7cm 
ANOXIC 


7-l2cm 
ANOXIC 


0-5cm 
AEROBIC 


AMC-4 
8-13cm 
ANOXIC 


13- 18cm 

ANOXIC 


1- -Hexadecane 


33 




3 


,b 


45 


? 


? 




i 


7 


14 
1- C-Heptadecane 


25 




1 





34 





? 


20 


0.5 


0.6 


14 
1- C-Heptadecene 


28 







? 


34 








72 


0.4 


1.4 


Ring- C-Toluene 


27 




2 


1.4 


34 


2.3 


2.9 


28 





? 


14 

Methyl- C-Toluene 


18 




? 


? 


29 


5 


1.4 


23 


9 


7 


l-(4,5,8)- U C- 
Naphthalene 


72 










78 














14 
U- C-Benzene 


26 







2 


45 








25 








7,10,- 14 C- 

Benzo(a)pyrene 


3 




























a Initial levels ranged from 0.22-2.2 x 10 DPM/vial 

14 
b Indicates that CO. was apparently present but was not quantifiable because levels were near detection 

limits 



40 ooo r 




FIGURE 6. 



CO2 production from [ ring- 1 '*C] -toluene during dark anaerobic 
incubation with sediments from the Aber Wrac'h 5-10 cm interval. 
Radiolabel was added at the beginning of the incubation period 
or 38 hours after incubation began (late addition) . Bars indi- 
cate one standard deviation. 



174 



14 
TABLE 5. Recovery of C following long term incubation with sediment 

collected at Aber Wrac'h, March 1979 





COMPOUND/DEPTH 






% RECOVERED IN 








co 2 


CH, 

4 


C0 o +CH, 
2 4 


F l 


F 2 


F 3 


14 
1- C-Heptadecane 














Mean of Controls 


— 


-- 


-- 


98.6 


0.5 


0.8 


0-5cm Aerobic 


6.0 


3.0 


(9.0) 


89.4 


0.5 


1.2 


5-10cm Anoxic 


3.1 


0.3 


(3.4) 


95.7 


0.4 


0.5 


10-15cm Anoxic 


3.9 


-- 


(3.9) 


94.9 


0.5 


0.6 



14 
1- C-Heptadecene 



Mean of Controls 


— 


— 


0-5cm Aerobic 


3.5 


6.2 


5-10cm Anoxic 


3.9 


1.2 



(9.7) 
(5.1) 



Unpurified Radioisotope 
Repurified Radioisotope 



91.5 


2.9 


5.6 


84.0 


2.9 


3.5 


89.0 


2.2 


3.6 


87.8 


5.6 


6.6 


99.4 


0.06 


0.5 



chamber sealed under a H„ + CO atmosphere. As shown in Table 6 these 
incubatioiL conditions did not prevent the slow, albeit variable, gener- 
ation of CO.. 



Effects of Oiling on Anaerobic Process 

Evidence for effects due to AMOCO CADIZ oiling was first sought by 
comparing anaerobic processes at sites oiled or not oiled by this 
spill. Sulfate reduction dominated methane production at all sites 
(the ratio of sulfate reduction rate to the sum of sulfate reduction 
and methane production rate ranged from 0.951-0.998, even though me- 
thane production may have been overestimated). Thus, major changes in 
the type of terminal process were not evident during the period of our 
experimentation. The potential use of acetate by either of these two 

175 



IGO 3-6 cm slurry 




IGO 3-6cm slurry 

l- l4 C-Hexodecone 



and 
'Formalin Controls 



DAYS 

14 
Figure 7. C0„ production during dark anaerobic incubations of repuri- 

f ied f , f„ and f fractions of radiolabelled hydrocarbons 

with a slurry made from the 3-6 cm interval of lie Grande 

oiled sediment. Bars indicate one standard deviation. 

14 
TABLE 6. Recovery of C following dark incubation with a 3-6 cm Aber 

Wrac'h sediment slurry in double anaerobic incubator (± 1SD) 



COMPOUND 



CO, 



% RECOVERED IN 



1 



14 
1- C-Hexadecane 

14 
1- C-Heptadecane 



3.94±3.48 
16.4123.6 



96. 1+3.48 
83.4±23.6 









0.2 



176 



14, 



groups makes [2- C] -acetate metabolism a useful means of differentiat- 
ing the importance of bacterial processes which accomplish its oxida- 
tion to C0„ (sulfate reduction) or its conversion to CH, (methane 
production, see Fig. 1). [2- C]-acetate was metabolized only to C0„ 
at all sites except in the surface layer of the oiled lie Grande site 



where small amounts of 






CH, were detected on one occasion (March, 
1979). This observation, however, was not repeated at later sampling 
dates. Rates of sulfate reduction were highest in the surface layer 
and decreased with depth in all sites (Fig. 8). Rates in the 0-3 cm 
intervals were higher in oiled compared to control Aber mudflat sedi- 
ments (p = .004). In the beach and salt marsh mudflat sediments , rates 
were higher in control sites than in oiled sites (p < .001). It is not 
possible, however, to attribute differences to the presence of AMOCO 
CADIZ oil since other differences between sites (e.g., amount of or- 
ganic loading) could also explain differences in sulfate reduction. 



ABER ILDUT 



ILE GRANDE 




SULFATE REDUCTION RATE (pmoles S0 4 = ' mf'-day" 1 * 



Figure 8. Depth profiles for rates of sulfate reduction in oiled and 
control sediments. Bars indicate one standard deviation. 



To more directly observe the effect of oiling on microbial activi- 
ties in sediments, AMOCO CADIZ mousse was added to lie Grande sedi- 
ments, and activities compared between mousse- treated and untreated 
sediments. Gas chromatograms of the saturate and aromatic fractions of 
this mousse are shown in Figures 9 and 10, respectively. These tracings 
can be compared to fresh light Arabian Crude in Figures 9 and 10. In 
the saturate fraction of the mousse, no hydrocarbons below C-12 were 
detected. In the aromatic fraction all predominant compounds were gone 
and only a UCM remained. Thus, extensive weathering of the low mole- 
cular weight compounds in the mousse had occured before collection. 
Extensive biodegradation of aliphatic compounds was not suggested as 
evidenced by the dominance of normal compared to isoprenoid alkanes. 

177 



FRESH OIL 




hk 



UjlAdU-uJM^vA. 



i^w*XaAj-JL- 




8h WEATHERING 



li 



jMJwmXiJL. 



48 h WEATHERING 



L i _JLkAiLujW-ujMOi'L 



o*u 



JJ 



L_*Ji 




LJL-JL 



44 d AMOCO -CADIZ MOUSSE 



L 



jlJJL-LUl 



Figure 9. Gas chromatograms of saturate fraction of light Arabian crude 
oils and Amoco Cadiz mousse. 

Table 7 shows the effect of the addition of 5% and 25% mousse (v/v) 
on sulfate reduction in sediments from the oiled and unoiled site at 
He Grande. A slight inhibition of sulfate reduction rate was observed 
at the control site, while a slight stimulation was observed at the 
oiled site. These rates, however, were not significantly different 
from the unoiled controls (p ^ 0.08). No significant differences in 
methane production between control sediments and sediments treated with 



178 



FRESH OIL 



u 



-Jul! 



JIUW'l/uvsU.L *~^" 



8 h WEATHERING 



Uul 



-fjJK 






' 4\ 



\Ju**-**~^ 



48 h WEATHERING 



L^. 



_UL 



_jj ^ 



44 d AMOCO-CADIZ MOUSSE 




WWvVA 



Figure 10. Gas chromotograms of aromatic fraction of light Arabian 
crude oils and Amoco Cadiz mousse. 



mousse were observed at either site ifjata not shown). Table 8, shows 
the effects of mousse additions on [2- C]-acetate oxidation to CO . 
No' CH, was detected in any of the samples. At the unoiled control 
site, the addition of 5% mousse decreased the amount of CO produced 
in 2h by 70% (p = 0.02), while an 86% inhibition was observed with the 
additions of 25% mousse (p = 0.01). At, the oiled site at lie Grande, 
mousse additions appeared to inhibit CO production from [2- C]- 
acetate although these differences were not significantly different 
from the control (p ^ 0.25). 

The effect of fresh and slightly weathered light Arabian crude oil 
on microbial activities in sediments was also examined because of the 
probable chemical differences between the highly weathered mousse and 
the oil which impacted the sites studied. The effect of 0.05% benzene 
and toluene was also examined. They are highly volatile aromatic com- 
pounds with known inhibitory effects (Robertson et al, 1973). Figure 9 
shows chromatograms of the saturate fraction of the fresh and weathered 
light Arabian crude. The fresh oil contained large amounts of low 



179 



TABLE 7. Effect of AMOCO CADIZ Mousse on Sulfate Reduction in Marsh 
Sediments 



lie Grande Control lie Grande Oiled 

Addition Rate % of Control p Rate % of Control p 



Control 


4.99 


100% 


- 


1.64 


100% 


- 


5% Mousse 


3.16 


63 


.08 


2.36 


144 


.15 


25% Mousse 


3.53 


71 


.14 


1.67 


102 


.95 



a Sediment samples were collected in November, 1979. 
Rates are the mean of 3 replicates and expressed as jjmoles S0,-S/ml/d. 



14 14 

TABLE 8. Effect of Mousse on [2- C]-Acetate Metabolism to C0 2 in 

Marsh Sediments 



, lie Grande Control , lie Grande Oiled 

Addition 3 C0 2 D % of Control p C0 2 % of Control p 



Control 


513 


100% 


- 


184 


100% 


- 


5% Mousse 


156 


30% 


.02 


115 


63% 


.41 


25% Mousse 


72 


14% 


.01 


78 


42% 


.25 



a Sediment samples were collected in November, 1979. 
Mean of 3 replicates expressed as DPM x 10 

molecular weight compounds which decreased relative to less volatile 
n-alkanes (e.g., C-24) in the 8h and 48h weathered oil. Octane and 
other compounds of similar volatility were nearly depleted after 48h of 
evaporative weathering. Figure 10 shows the aromatic fractions of each 
of the oils used. After 8h of evaporative weathering, toluene and sev- 
eral other volatile aromatic compounds were significantly reduced, and 
after 48h most of the predominant volatile aromatics were evaporated. 

180 



Table 9 reports the effect of these oil and aromatic additions on 
sulfate reduction rates in lie Grande surface sediments. At the unoiled 
control site, all oil additions decreased the rate of sulfate reduction 
although not significantly below the control (p ^ 0.16). The greatest 
inhibition was observed for toluene and benzene additions (p = 0.10 and 
0.09 respectively). At the oiled site, rates under all conditions were 
not significantly different from the control rate. The effect of the 
oil, benzene, and toluene additions on methanogenesis (results not 
shown) were variable. None of the additions resulted in a rate of 
methanogenesis that was significantly different than the rate without 
additions . 



TABLE 9. Effect of Hydrocarbons on Sulfate Reduction in Marsh Sedi- 

- a 
ments 



Addition 


lie 

Rate 


Grande Contro 
% of Control 


1 
P 


He 
Rate 


Grande Oiled 
% of Control 


P 


Control 


2.27 




100% 


- 


1.01 




100% 


- 


10% Fresh Oil 


1.67 




73 


0.95 


0.85 




84 


0.08 


10% 8 h Weathered 
Oil 


1.57 




71 


0.16 


0.87 




86 


0.11 


10% 48 h Weathered 
Oil 


1.82 




82 


0.97 


1.07 




106 


0.48 


.05% Toluene 


1.42 




64 


0.10 


1.11 




110 


0.23 


.05% Benzene 


1.32 




59 


0.09 


1.13 




112 


0.15 



Sediment samples were collected in April, 1980. 

Rates are the mean of 3 replicates and expressed as |jmoles S0,-S/ml/d. 

14 
The effect of the oil and aromatic additions on [2- C] -acetate 

oxidation to CO in He Grande is shown in Table 10. At both the 
oiled and unoiled site, the amount of C0„ produced in 2 h was signi- 
ficantly reduced (p S 0.01) with all of the additions. In general, the 
magnitude of inhibition was greater at the control site (76-97%) than 
at the oiled site (51-93%). In both sites inhibition was greatest with 
the unweathered oil and decreased with the extent of weathering of the 
oils . 



181 



14 
TABLE 10. Effect of Hydrocarbons on [2- C]-Acetate Metabolism to 

CO- in Sediments 



Addition 


w He Grande Control 
C0 2 % of Control 


P 


14 co 2 * 


Grande Oiled 
% of Control 


P 


Control 


358 100% 




244 


100% 




Fresh Oil 


10 3 


0.00 


17 


7 


<0.001 


8 h Weathered 
Oil 


44 12 


0.01 


66 


27 


<0.001 


48 h Weathered 
Oil 


87 24 


0.01 


119 


49 


<0.001 


Toluene 


29 8 


0.002 


86 


35 


<0.001 


Benzene 


31 9 


0.002 


65 


27 


<0.001 



Sediment samples collected in April, 1980. 
Mean of 3 replicates expressed as DPM x 10 



DISCUSSION 



The major objectives of this study were to address the fate and 
effects of hydrocarbons from the AMOCO CADIZ spill in anaerobic sedi- 
ments. It is first necessary to consider the chemistry of the various 
intertidal sediments with respect to exposure to oxygen. A great deal 
has been learned recently due to the application of microelectrodes to 
the study of oxygen distribution and dynamics in marine subtidal and 
submerged intertidal sediments (Revsbech, et al, 1980a, b). A variety 
of sediments (including medium — grained sands) exhibited very narrow 
oxygenated intervals ranging from 2-10 mm below the sediment water in- 
terface. Oxygen depletion has been measured to occur above the verti- 
cal discontinuity of Eh in coastal sediments (Revsbech, et al, 1980a). 
Thus the Eh profile of a sediment may serve as a conservative estimate 
for the aerobic/anoxic boundary. Eh profiles then indicate that anoxic 
conditions were likely below 1 cm in the He Grande oiled site and be- 
low 2-3 cm in Aber Wrac'h sediment. The real depth of oxygen penetra- 
tion at any given time is likely to be less. Changes in color from 
brown to black at about 2 mm in the He Grande oiled sediment may in- 
dicate an extremely narrow aerobic zone. Similar color changes in Aber 
Wrac'h at about 2-3 cm may indicate that net oxygen penetration in this 
sediment is deeper, but oxidants other than oxygen could keep Eh high- 
er. The Eh profiles were measured on undisturbed sediments and pro- 

182 



bably reflect the chemistry of sediments under relatively calm condi- 
tions. Mixing which occurs as a result of tidal or storm driven wave 
action might alter the depth to which oxygen can penetrate sediments. 
This should vary with the nature of the sediment so that muds should be 
less affected than sandy sediments on high-energy beaches. Over sea- 
sonal time intervals, it is likely that the aerobic/anoxic boundaries 
predicted by Eh profiles are preserved in the muddy sediments sampled. 
However, it is likely at the oiled beach AMC-4 that erosion and deposi- 
tion created considerable instability in the depth of oxygen penetra- 
tion and could even have caused vertical redistribution of sediments 
(Gundlach and Hayes, 1978). It is also possible that oxygen could be 
introduced to depths below the lower boundary of its diffusion by sedi- 
ment infauna which can burrow into anaerobic sediments. 

The vertical distribution of the dominant anaerobic process, sul- 
fate reduction, indicated maximum activity in the surface 0-3 cm inter- 
val at all stations. The obligately anaerobic sulfate-reducing and 
methane-producing bacteria were also present in maximum number in the 
0-3 cm depth interval (Winfrey and Ward, submitted). These observa- 
tions suggest that at least portions of the 0-3 cm interval at all 
sites were sufficiently anoxic to allow survival and activity of obli- 
gately anaerobic microorganisms. 

A survey of the various sediments sampled confirmed the presence 
of AMOCO CADIZ pollutants in oiled sites. Although control sites were 
not polluted by the AMOCO CADIZ spill, each contained some hydrocarbons 
of anthropogenic origin. The extent of oiling was greatest at the sedi- 
ment surface where anaerobic processes were greatest. Oiling decreased 
with depth, but there was clear evidence of AMOCO CADIZ hydrocarbons in 
sediments likely to be free from exposure to oxygen. Sediments below 
the aerobic/anoxic boundary and above the deepest level of penetration 
of AMOCO CADIZ pollutants provided an environment suitable for the en- 
richment of anaeroDic hydrocarbon-degrading microorganisms, and appro- 
priate for comparison to aerobic surface sediments to study the differ- 
ences in weathering in situ due to different exposures to oxygen. 

Because of the rapid biodegradation of aliphatic components and 
relative enrichment of aromatic components of the spilled oil (Atlas, 
et al, 1981; Ward, et al, 1980), ratios of naphthalenes, phenanthrenes 
and dibenzothiophenes to the more persistent C -DBT were used as an 
index of weathering. This index should be independent of absolute 
amounts of oil within sediment samples which could vary due to patchy 
distribution of oil. Changes in sediment aromatic hydrocarbons oc- 
curred in all sediments and at all sediment depths where comparisons 
were made for one year or longer. The greatest and most rapid changes 
were noted in surface sediments of the beach station AMC-4 where most 
compounds had decreased by one year after the spill and extensive 
losses had occurred by about 20 months after the spill. This seems 
consistent with the expected mixing and oxygenation of this high energy 
beach sediment. In muddy sediments , slower changes in relative amounts 
of aromatic compounds were noted. Extensive losses were observed main- 
ly among the naphthalenes and DBT's. This may have been related to the 
low energy nature of these sediments and/or the corresponding lack of 
oxygenation indicated by reducing conditions. Decreases in these com- 

183 



pounds were, however, noted at depths below the minimum Eh 20-26 months 
after the oil spill. It is difficult to rule out exposure to oxygen in 
these subsurface muddy- sediment environments. The degree of storm 
driven mixing and/or irrigation by sediment fauna are unknown and might 
be significant over a 12-18 month time course. More than two years 
after the AMOCO CADIZ spill many well resolved aromatic compounds per- 
sisted (e.g., phenanthrenes) ; however, the slow disappearance of some 
aromatic hydrocarbons (e.g., naphthalenes) from subsurface muds may 
indicate that these resolved compounds will not persist indefinitely. 

14 
The potential biodegradation of hydrocarbons measured using C- 

labelled hydrocarbons was much lower under anaerobic than under aerobic 
conditions. For example, 33% of added [1- C] -hexadecane was converted 
to C-gases aerobically, whereas only 3% was converted anaerobically 
after 233 days in Aber Wrac'h sediment (Table 4). Due to the expected 
high oxygen demand of the surface sediments, it is likely that 0„ deple- 
tion occurred rapidly in vials incubated aerobically. Thus, it is got 
surprising that complete conversion of added C-hydrocarbons to C- 
gases did not occur in long term aerobic incubations. Since the added 
radiolabelled hexadecane (4.2 |jg/sample) exceeded the indigenous hexa- 
decane measured in these sediments (16-174 ng/sample), potential rates 
of aerobic and anaerobic metabolism can be calculated by multiplying 
the percentage conversion by the amount of hexadecane added and divid- 
ing by the number of days incubation and dry weight of the sample. The 
maximum level of C-gases produced under aerobic conditions was de- 
tected at the earliest analysis time (66 days). This leads to a cal- 
culated rate of 13.8 ngm/gm-dry weight/day. The true potential rate is 
probably greater due to incomplete exposure of the entire sample to 
oxygen and to oxygen depletion. Calculations using rates of oxygen 
consumption for European coastal sediments suggest that oxygen should 
have been completely consumed within the first ten days of incubation. 
The corresponding rate would be 91 ngm/gm-dry weight/day, approximately 
one-fifth of the potential rate reported by Atlas and Bronner (1981). 
C-gases increased with time during anaerobic incubation. The corre- 
sponding potential anaerobic rate of hexadecane metabolism after 233 
days incubation of 0.3 ngm/gm-dry weight/day is 46 times slower than 
the measured potential aerobic rate and over 300 times slower than the 
aerobic rate calculated from reasonable assumptions about the condi- 
tions under which aerobic controls were run. These results are similar 
to other reports which demonstrate the severe limitations on hydrocar- 
bon metabolism imposed by reduced amounts or lack of oxygen (Ward and 
Brock, 1978; Hambrick, et al, 1980; DeLaune, et al, 1981). It was in- 
teresting that no evidence was obtained for anaerobic naphthalene oxi- 
dation. Obvious problems of naphthalene volatility may have decreased 
the amount actually added to vials thereby lowering the sensitivity for 
detecting its oxidation. 

As in earlier studies (Ward and Brock, 1978), it was not possible 
to eliminate metabolism of hydrocarbons under stringent anaerobic con- 
ditions. It was important to investigate the possibility that slow 
anaerobic oxidation might occur in order to predict whether or not hy- 
drocarbons buried in permanently anoxic sediments persist indefinitely. 
Controls were run against the possibility of initial accidental inclu- 
sion of oxygen, photosynthetic oxygen production, oxygen leakage into 

184 



experimental vials during incubation, and against the possibility that 
compounds contaminating radiolabelled hydrocarbons were the sources of 
C-gases. The results of these experiments were consistent with the 
conclusion that slow anaerobic oxidation of some petroleum hydrocarbons 
may be occurring in anoxic sediments polluted with AMOCO CADIZ oil. 

A second major objective of this work was to study the effects of 
AMOCO CADIZ oil on the dominant anaerobic processes within sediments. 
As mentioned above, oiling was heaviest in the surface sediments where 
anaerobic processes occurred at maximum rates. We were unable to moni- 
tor any immediate effects of the AMOCO CADIZ spill because our first 
sampling trip was in December 1978, 9 months after the spill. We were 
also limited by the lack of any data on the microbial activities in our 
sampling sites prior to the oil spill. However, by examining unoiled 
sites, we were able to see if any major alterations in chemistry and 
activities had occurred in the oiled sediments. 

Comparisons between oiled and unoiled sites revealed lower rates 
of sulfate reduction in oiled beach and marsh sediments. It is not 
possible, however, to attribute these differences to the presence of 
AMOCO CADIZ oil because 1) inhibition was not observed at all sites 
where oiling occurred, 2) the magnitude of differences observed was 
small (largest difference was 51% of the control), and 3) other dif- 
ferences between sites which could influence sulfate reduction rate 
(e.g., organic loading) were unknown. It is also difficult to inter- 
pret whether rates measured in control sites were typical of unpolluted 
sediments, as hydrocarbon analyses revealed a previous history of oil- 
ing in control sediments. No differences in methane production or ace- 
tate metabolism were, noted. Although preliminary results demonstrated 
small amounts of CH, production from [2- C]-acetate at the lie 
Grande oiled site (Winfrey and Ward, 1981), this observation was not 
confirmed in subsequent work. Sulfate reduction always dominated me- 
thane production and acetate was metabolized only to CO . The lack 
of profound differences in comparative experiments performed 9-18 
months following the spill, suggest that no long-term effects on an- 
aerobic processes occurred in these sediments. 

We examined the effect of an unweathered oil on anaerobic pro- 
cesses in order to determine whether any short-term effects of oiling 
might have occurred. A fresh light Arabian crude oil did not signi- 
ficantly effect sulfate reduction or methane production, but inhibited 
acetate oxidation 93-97% in oiled and control sediments from lie 
Grande. The ability of the crude oil to inhibit acetate oxidation was 
reduced in oil samples which had been evaporated to increasing degrees. 
Highly volatile molecules such as toluene and benzene caused 91-92% 
inhibition in control sediments and 65-73% inhibition in oiled sedi- 
ments. The data suggest that volatile components of the oil may be re- 
sponsible for inhibitions to acetate oxidation. However, mousse col- 
lected near He Grande 44 days after the AMOCO CADIZ spill also inhi- 
bited acetate oxidation at the He Grande control site. This mousse 
sample had lost most of its more volatile components, but was appar- 
ently not extensively altered by biodegradation. Inhibitions were al- 
ways greater at the control site than at the oiled site. Thus, the 
oiled area of the marsh appears to have become less sensitive to the 

185 



effects of additional heavy oiling. This may be a result of an adapta- 
tion of microorganisms to the presence of oil, or to a selection of oil 
resistant populations. 

It is not surprising that hydrocarbons did not directly inhibit 
sulfate reduction since this process appears to be active in oil forma- 
tion waters (Bailey, et al., 1973; ZoBell, 1958). However, it was sur- 
prising that compounds which inhibited acetate oxidation did not dir- 
ectly inhibit sulfate reduction, as other investigations have pointed 
to the importance of acetate as a substrate for sulfate reduction (Win- 
frey and Ward, submitted; S<f>rensen et al, 1981; Banat and Nedwell, per- 
sonal communication). 

The chemistry of hydrocarbons present in the various sediments one 
year after the spill indicated the presence of oil highly altered by 
evaporation and biodegradation. The levels observed in the environment 
were also lower (0.1-1 mg/g) than the levels added in our experiments 
to simulate heavy oiling (50-250 mg/g). It is possible that a tempor- 
ary inhibition of acetate oxidation could have resulted from very heavy 
oiling of relatively fresh oil. Such conditions could have existed at 
all polluted sites immediately following the AMOCO CADIZ spill, al- 
though rapid loss of volatile compounds probably occurred between 
spillage and beaching of oil (Dowty, et al, 1981; Ward, et al, 1980). 
Any inhibitory effect would then have been reduced as cleanup or trans- 
port of hydrocarbons out of the sediments decreased hydrocarbon amount, 
and as evaporation, dissolution and biodegradation altered the remain- 
ing sediment hydrocarbons. By the time site comparison experiments 
could be performed, recovery from any negative effects which might have 
occurred had apparently taken place. The inhibitory effects on acetate 
oxidation we observed may be significant in extremely cold regions 
where slow rates of evaporation would occur. 



ACKNOWLEDGEMENTS 

We are indebted to the Centre Oceanologique de Bretagne at Brest 
and the Station Biologique at Roscoff for providing laboratory space 
and assistance. We also thank Bob Clark of the NOAA National Analyti- 
cal Facility for supplying AMOCO CADIZ mousse, George Ward of Exxon 
Corp. for supplying the light Arabian crude oil, and Dale Meland and 
Melinda Tussler for technical assistance. 

This study was part of a joint effort undertaken by the Centre Na- 
tional pour 1' Exploitation des Oceans (CNEXO) of the French Ministry of 
Industry and the NOAA of the U.S. Department of Commerce to study the 
ecological consequences of the AMOCO CADIZ oil spill. It was financed 
by funds given to NOAA (contract NA 79RAC00013) by the Amoco Transport 
Company and by the NOAA Outer Continental Shelf Environmental Assess- 
ment Program, through an interagency agreement with the Bureau of Land 
Management. 



186 



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190 



PART II 

Biological Studies 
After the AMOCO CADIZ Oil Spill 



Edited by M. Marchand 
Centre Oceanologique de Bretagne 
Brest, France 



REPONSES DES PEUPLEMENTS SUBTIDAUX A LA PERTURBATION CREEE PAR 
L' AMOCO CADIZ DANS LES ABERS BENOIT ET WRAC'H 

par 

Michel GLEMAREC et Eric HUSSENOT 

Laboratoire d'Oceanographie biologique , Institut d'Etudes Marines, 
Faculte des Sciences et Techniques, 29283 Brest Cedex 

ABSTRACT 

During three years after the Amoco- Cadiz oil-spill, the succes- 
sion in time of different ecological groups with regard to excess of 
organic matter, allow to define chronological process. First^ total 
disappearance of sensible and tolerant species by toxicity. When 
pollution is stabilized, we describe appearance, development and 
regression of an opportunist fauna, finally the excessive develop- 
ment of tolerant species before return to a new equilibrium. This 
temporal succession is studied along two different gradient of de- 
creasing hydrodynamism, the abers , where the chemical decontamina- 
tion and the biological process are not synchronized. Near three 
years after the oil-spill most communities are still perturbated 
and unbalanced. Patterns of temporal evolution and succession is 
discussed. 



INTRODUCTION 

Les deux Abers, Benoit et Wrac'h, sont situes a proximite de 
l'echouage de l'Amoco-Cadiz (Fig. 1). C'est l'aire qui a ete la plus 
affectee par la maree noire. Depuis , de nombreuses etudes ont con- 
cerne ces abers et 1' analyse des successions ecologiques au sein des 
communautes de l'endofaune s'est averee tres interessante dans le 
cas d' etudes a moyen et long terme. Sont apparues des fluctuations 
temporelles non saisonnieres mais evolutives, qu'il est possible de 
synthetiser trois ans apres l'echouage. 

Apres la destruction quasi-complete des communautes d'origine, 
la recolonisation passe par le developpement transitoire d'une 
faune speciale, caracterisant un exces de matiere organique sur les 
fonds sedimentaires . Notre approche consiste d'abord a reconnaitre 
les groupes taxonomiques , constitues par les especes de polluosensi- 
bilite equivalente en face d'un exces de matiere organique. Leur 
apparition successive dans le temps, leur disparition, constituent 
les parametres obligatoires de cette approche dynamique . Ce type 
d' analyse montre comment une perturbation biologique peut persister 
longtemps dans l'ecosysteme , alors que les facteurs ecologiques 
semblent normaux. Le long du meme gradient ecologique spatial, 
1' etude comparee des deux Abers peut montrer des differences dans 
les vitesses de retour a un nouvel equilibre. 



191 




FIGURE 1. Localisation de l'epave de l'AMOCO-CADIZ (A-C) par rapport 
aux deux abers, ou sont representees les differentes unites 
biosedimentaires . 

METHO-DES 

La macrofaune qui vit dans les aires sedimentaires est etudiee 
le long des chenaux subtidaux de ces deux Abers. Cinq prelevements 
sont realises a chaque station avec une benne "Aberdeen". Ces echan- 
tillons sont repetes trois fois dans l'annee (hiver, printemps , ete). 
Les stations -plus de quinze dans chaque Aber- sont representatives 
des differents peuplements. Leur distribution spatiale de l'aval vers 
l'amont est la suivante (Gentil et Cabioch, 1979 ; Glemarec et 
Hussenot, 1981) : sables grossiers (SG), sables dunaires fins et 
moyens (DU), sables fins et envases (FV), sables heterogenes envases 
(SHV) et vases sableuses (VS). 

Cette distribution (Fig. 1) correspond a un hydrodynamisme de- 
croissant et, inversement , a une accumulation croissante d'hydrocar- 
bures dans les sediments (Marchand et Caprais , 1981). Dans l'Aber 
Benoit , la repartition est en partie differente parce que les sables 
dunaires sont tres developpes. II y a une vaste accumulation en aval 
(DUi) sous la pointe de Corn ar Gazel et , au milieu du chenal, deux 
unites quelque peu differentes, DU2 et DU3 , la derniere est en con- 
tact avec les sables heterogenes envases (SHV). Les sables fins 
n' existent pas dans le chenal, mais sont localises en aval dans une 
aire protegee entre des plateaux rocheux, collectant les particules 
fines qui peuvent sortir dans l'aber. 



RESULTATS 

Tout d'abord -phase premiere de Marchand (1981)- la toxicite 
des hydrocarbures a induit de lourdes mortalites au sein de toutes 
les communautes (Chasse, 1978, Cabioch et at., 1979). D'autres es- 
peces, plus opportunistes , s'installent dans une deuxieme phase 
(Glemarec et Hussenot, 1981 ; Le Moal et Quillien-Monot , 1981). 



192 



Les nouvelles populations caracterisent un exces de matiere organique, 
dans le cas d' effluent urbain arrivant en mer par exemple . Apres dif- 
ferents travaux sur ces problemes (Pearson et Rosenberg, 1978 ; 
Bellan et al. , 1980 ; Glemarec et Hily, 1981) il est possible de 
regrouper ces especes en fonction de leur polluosensibilite . 

Grouge_I : especes sensibles, largement dominantes en conditions nor- 
males . Elles different selon chaque type de peuplement . Dans les 
sables dunaires fins et moyens par exemple, les Amphipodes sont nom- 
breux (Bathyporeia spp., Ampelisoa spp . ) ; ils meurent rapidement 
dans tous les cas de maree noire (Chasse et al . , 1967 ; Cabioch et 
al., 1980 ; Sanders, 1978 ; Pfister, 1980). 

Grouge_II : especes tolerantes , toujours en petites quantites. Elles 
ne fluctuent pas significativement dans le temps. La majorite d'entre 
elles sont des predateurs : Nephtys hombergii, Morphysa bellii , 
Glyaera spp.., Platynereis dumevilii ... 

* 
Groupe_III : especes sensibles qui disparaissent tout d'abord puis 

reapparaissent en elargissant leur repartition ecologique par rap- 
port aux conditions normales : Spio spp., Notomastus lateriaeus, 
Phyllodoae spp., Nereis diversiaolor ... 

Grouge_IV : especes opportunistes , essentiellement des Polychetes 
Cirritulides et Capitellides (Chaetozone setosa, Heteroairrus spp., 
Polydora spp., Cirratulus oirratulus, Andouinia tentaculata, Capito- 
mastus minimum ...). A l'interieur de ce groupe une succession eco- 
logique a pu etre precedemment definie (Glemarec et Hussenot , 1981 ; 
Le Moal, 1981). 

Groupe V : especes opportunistes, tres peu nombreuses (2 ou 3) qui 
restent seules mais sont presentes en densites considerables la ou 
la pollution est maximale : Capitella capitata, Capitellides giardi, 
Soolelepis fuliginosa, Oligochetes . . . 

Ces differents groupes peuvent coexister et le long du gradient 
de pollution organique , six etapes peuvent etre definies (Fig. 2a) : 
Etage_l : groupes I, II et III sont en plus faibles densites qu'en 
conditions normales, mais il n'y a aucun changement qualitatif. 

Etage_2 : l'ecosysteme est desequilibre et le groupe III est domi- 
nant . 

Etapes_4_et_6 : elles sont definies respectivement par la prolife- 
ration des groupes IV et V. 

Etap_es_3_et_5 : elles correspondent a des ecotones ; le groupe II 
est seul car la competition entre groupes est affaiblie . 

Ce diagramme (adapte de Glemarec et Hily, 1981) est statique. 
II illustre par exemple la disposition d 'aureoles concentriques de 
pollution decroissante en face d'un effluent urbain arrivant en mer. 
La perturbation creee par 1' AMOCO-CADIZ apporte une nouvelle dimen- 
sion temporelle a ce diagramme. Nous proposons de decrire 1' instal- 
lation progressive des differents groupes (Fig. 2b) et la regression 
de cette faune speciale de substitution (Fig. 2c). 



*•. . . , 

a la toxicite des hydrocarbures , 



193 




FIGURE 2a. Importance relative des differents groupes et definitions 
des etapes a 6 le long du gradient d'exces en matiere 
organique . 

2b. Installation de la faune opportunists (groupes IV et V) 
apres stabilisation de la pollution. 

2c. Evolution regressive de la faune opportuniste et develop- 
pement du groupe III. 



Trois mois apres la perturbation (t3), la population est large- 
ment stabilisee, c'est le debut de la deuxieme phase de Marchand . 
A t8, tous les peuplements sont detruits (Fig. 3 et 4). On notera 
que dans l'Aber Wrac'h, quelques especes tolerantes ou du groupe IV 
meurent ulterieurement (t2l). Dans l'Aber Wrac'h, les sables gros- 
siers d'aval ne sont pas affectes (etape 0, cf. Tableau 1), le peu- 
plement montre seulement quelques fluctuations saisonnieres . Partout 
ailleurs les hydrocarbures sont stockes dans les sediments en fonc- 
tion de l'hydrodynamisme decroissant de l'aval vers l'amont, et il 
est possible de decrire 1 'installation des differents groupes d 'es- 
peces le long du mime gradient . 

Dans les sables dunaires (DUi) de l'Aber Benoit (Tableau II), 
la teneur d' hydrocarbures est partout inferieure a 50 ppm et la com- 
munaute montre une legere baisse des densites (etape 1) et une etape 2 
de desequilibre apparait , de facon f ugace . Pour tous les autres sedi- 
ments des deux abers , la ou la teneur en hydrocarbures est toujours 
superieure a 1 000 ppm (Marchand et Caprais, 1981), leurs peuplements 
sont tres appauvris . 

194 



TABLEAU I. L' evolution des peuplements dans l'ABER WRAC'H est illus- 
tree par 1' utilisation des etapes definies sur la Figure 2 



t 


8 


13 


17 


21 


25 


29 


35 


vs 


- 


- 


6 


5 


4 


2 


2-6 


SHV 


4 


4 


4-2 


4-2 


4 


- 


2-4 


FV 


4 


4 


4-2 


3 


4 


3 


3 


SF 


4 


4 


4-2 


2-4 


4-2 


2-4 


2-4 


DU 


4 


4 


4-2 


2-4 


4-2 


1 


O 


SO 

















- 





TABLEAU II.L'evolution des peuplements dans l'ABER BENOIT est illus- 
tree par 1 'utilisation des etapes definies sur la Figure 2 



t 


8 


15 


- — — 1 

17 


21 


25 


29 


33 


vs 


6 


6 


6-2 


2-6 


6-2 


6-2 


6-2 


SHV 


4-2 


4-2 


2-4 


2-4 


2 


6 


2-4 


DU 3 


4-2 


4-2 


6-2 


2-6 


2 


2 


2 


SF 


- 


4 


4 


2 


2-4 


4-2 


2-4 


DU 2 


4 


1 


1 


1 


1 


1 


2 


DU] 


1 


1 


1 


2 












A partir de t8 le groupe IV est predominant sur les groupes I 
et III (etape 4). Dans les aires envasees d'amont, les peuplements 
sont tres sinistres et le groupe V prolifere (etape 6). Neanmoins , 
dans l'Aber Benoit, les peuplements de la partie moyenne (DU3 et SHV) 
montrent deja la predominance du groupe III sur le groupe I, ce qui 
definit une etape intermediaire 4-2 qui apparait a t8 dans l'Aber 
Benoit mais seulement a ti7 dans l'Aber Wrac'h. Le long du gradient 
spatial d'exces en matiere organique de l'aval vers l'amont, les 
etapes successives 6 et 4 illustrent 1' apparition successive des 
groupes V et IV, les etapes intermediaires 6-2 et 4-2 celle du 
groupe III toujours domine par les groupes V ou IV. 

Les conditions hivernales , par leurs tempetes frequentes , 
brassent et oxygenent les sediments. Apres le premier hiver (ti2), 
Marchand et Caprais notent la decontamination chimique dans l'Aber 
Benoit au niveau des sables dunaires DUi et DU2 , puisque la teneur 
en hydrocarbures est inferieure a 100 ppm. Cependant , dans la ma jo- 
rite des autres sediments, cette teneur, a t]_2, est toujours supe- 
rieure a 1 000 ppm et peut atteindre plus de 10 000 ppm dans les 
vases et dans les sables heterogenes envases . C'est seulement durant 
le deuxieme hiver (t2l) que la decontamination peut etre prouvee par 
des donnees biologiques (Tableau I) dans 1 'ensemble de l'Aber Wrac'h. 
La Figure 2c illustre cette regression des groupes opportunistes V et 
IV, 1' extension puis finalement la disparition du groupe III avec les 
differentes etapes : 

etape 2-6 : le groupe III domine les groupes V et IV. 
etape 2-4 : le groupe III domine les groupes IV et V. 

195 



Du 



Sf 



Fv 



Shv 



Vs 



13 © 



17 © 



21 © 



25 



29 



T33 









©' 





FIGURE 3. Evolution temporelle de la densite des peuplements et de 

1 ' importance relative des different s groupes de I a V, ceci 
dans les differentes unites biosedimentaires de l'Aber Wrac'h, 
de l'aval a gauche vers l'amont a droite . 



196 



B 



Dui 



© 



Du 2 



© 



Sf 



Du 3 



® 



Shv 



© 



Vs 



© 



® 













FIGURE 4. Evolution temporelle de la densite des peuplements^et de 

1' importance relative des differents groupes de I a V, ceci^ 
dans les differentes unites biosedimentaires de l'Aber Benoit 
de l'aval a gauche vers l'amont a droite . 



197 



etape 2 : le groupe III domine les groupes I et IV. 

etape 1 : le groupe I domine le groupe III, le groupe IV est encore 

present, les densites totales sont encore plus faibles 

qu'en conditions normales . 

Ces quatre etapes prouvent que l'ecosysteme est encore desequi- 
libre. Le debut de 1' evolution regressive de cette faune de substi- 
tution semble simultane dans l'Aber Wrac'h. Dans l'Aber Benoit, 
cette evolution apparait differemment au sein des peuplements , plus 
rapidement la ou les sediments sont bien oxygenes , apres t8 pour les 
sables dunaires (DU2), apres ti3 pour les sables heterogenes envases 
(SHV), apres ti7 pour les sables fins, les DU3 et les vases sableuses 
(VS). Deux ans apres la perturbation (t25>, les sables dunaires (DUi) 
presentent un peuplement qui semble normal (etape 0), tous les autres 
peuplements sont en desequilibre (etapes 1, 2 et 2-4) et , dans les 
aires envasees , la decontamination commence a peine (etape 6-2). 
Ensuite les processus dynamiques sont plus lents et , au cours du 
troisieme hiver (t33), les sables dunaires ( DU2 et DU3 ) atteignent 
1' etape 2, les sables fins et les sables heterogenes envases l'etape 
2-4. 

Les dragages mecaniques qui ont ete preconises pour resorber 
les poches de vase et d'hydrocarbures ont eu lieu en avril 1980, a 
proximite des sables heterogenes envases. Leur peuplement temoigne 
d'un accroissement passager de la perturbation, etape 6 a t29- H 
faut moins de deux mois en effet pour que prolifere une nouvelle 
generation de Capitella capitata. Cette etape 6 est apparue comme 
une elevation dans 1 'evolution logique de l'ecosysteme ; elle est 
provoquee par une intervention anthropique . 

II est important de noter que les conditions hydrodynamiques 
ne sont pas aussi efficaces dans l'Aber Wrac'h que dans l'Aber 
Benoit, ce qui se traduit par une decontamination qui n'est pas si- 
multanee dans les abers . L' evolution regressive de la faune oppor- 
tuniste n'est pas aussi rapide dans l'Aber Wrac'h et nous pouvons 
observer qu'au meme moment (t25 par exemple ) , les memes peuplements 
restent plus perturbes que dans l'Aber Benoit : 

DU 2 SHV SF VS_ 
Abers Benoit 1 2 2-4 6-2 
Wrac'h 4-2 4 4-2 4 

A t33 cette difference disparait : 

DU2 SHV SF VS 
Abers Benoit 2 2-4 2-4 6-2 
Wrac'h 2 2-4 2-4 2-6 



DISCUSSION 

Independemment des fluctuations cycliques annuelles, Involu- 
tion temporelle des differents groupes le long des gradients spa- 
tiaux que constituent les abers, montre une evolution acyclique et 
des processus chronologiques tout a fait similaires de ceux decrits 
par Le Moal (1981) dans la zone intertidale de ces abers. lis sont 
resumes sur la Figure 5a. II y a d'abord regression quasi-totale des 

198 



populations initiales durant la premiere periode to~t8- Le groupe II 
ne fluctuant pas significativement ou etant seulement dominant lors- 
que les autres groupes disparaissent (etapes 3 et 5), n'est pas repre- 
sent^ sur les figures . 

Entre tg et t^3, c'est le commencement de la seconde phase et 
la faune opportuniste s'installe. Le groupe IV est abondant partout 
a partir de t8 dans l'Aber Wrac'h, ses densites sont maximales au 
printemps , c'est-a-dire a ti3 et t25- Son importance est decroissante 
dans les peuplements de l'Aber Benoit apres t8, ti3 ou t]_7 selon 
1 ' hydrodynamisme . 

Le groupe V apparait de facon significative seulement dans les 
vases sableuses de l'Aber Benoit, mais , sur un plan general, le de- 
veloppement de la faune opportuniste IV et V est maximal entre to 
et t20- 

Le groupe III reapparait a ti3 et son developpement est tres 
important partout durant le deuxieme hiver. De facon simultanee, le 
groupe I reapparait , un an apres la maree noire , mais apres deux 
annees son importance est encore limitee par le developpement anormal 
du groupe III qui semble entrer en competition. 

Avec le developpement des groupes I ou III, essentiellement 
apres t20 3 commence done la phase de reconstitution . A cote de ce 
schema general d' evolution, nous avons regroupe les differents sce- 
narios d'evolution temporelle : celui des vases sableuses de l'Aber 
Benoit est evoque plus haut (Fig. 5b), celui des vases sableuses de 
l'Aber Wrac'h montre d'abord la predominance du groupe V, remplace 
ensuite par celui du groupe IV (Fig. 5c). Pour les autres sediments 
de l'Aber Wrac'h, il y a deux pics successifs du groupe IV separes 
par un maximum du groupe III a t21- Le cas aberrant des sables hete- 
rogenes envases de l'Aber Benoit est illustre par la recrudescence 
du groupe V, apres celui du groupe IV. 

Pour 1' ensemble des sediments dunaires des deux abers , les Fi- 
gures 5d, e et f, illustrent les differentes possibilites ou la com- 
petition entre les groupes I et III apparait de facon tout a fait 
evidente . 

Ces scenarios sont etablis sur les densites relatives des diffe- 
rents groupes, mais la communaute sera jugee en etat d'equilibre 
lorsque les caracteristiques essentielles (A = abondance relative 
des especes ; S = nombre d'especes ; B = biomasse) restent relati- 
vement inchangees, hormis les fluctuations saisonnieres . Qualitati- 
vement , 1' ensemble de ces peuplements est encore en desequilibre et 
1' analyse simultanee des trois parametres S, A, B, suggere des faits 
complementaires qui meritent d'etre suivis dans le temps. On notera 
que c'est dans le cas des sediments d'aval de l'Aber Benoit que l'on 
est encore le plus eloigne d'une certaine stabilisation de ces trois 
facteurs . Au contraire , c'est dans le cas des sediments envases que 
l'equilibre semble atteint le plus vite . 

Nous avons deja expose (Glemarec et al. , 1981) comment le modele 
methodologique , mis au point dans le cas des effluents urbains arri- 
vant en mer, pouvait etre utilise dans le cas de catastrophes petro- 
lieres, et l'echelle de temps des phenomenes observes semble avoir 
ete la meme dans le cas du Tanio (Aelion et Le Moal, 1981). 

199 



Modele general ( intertidal par ex.) 




— i-* 
12 




VS 



vs w 

SHV^ 
SF w 
FV W 
SHV 8 



< 



m 



Er— »-iz: 



nr- 




sf B 

DU w 
DU,B 



du 3 s 




DU,8 



12 




FIGURE 5. Principaux modeles de succession temporelle des differents 
groupes I a V au sein des peuplements des Abers Wrac'h (W) 
et Benoit (B). Le modele general (Fig. 5a) est synthetique ; 
il illustre les trois phases apres une telle perturbation : 
mortalite, substitution, reconstitution. 

200 



vs 



w 



DU 



w 



VS/ 



' \ 
/ \ 
/ \ 




SHV W 



FV W 




DU,B 





FIGURE 6. Evolution des parametres synthetiques , nombre d especes S en 

trait plein, A abondance des individus en poxntille, B biomasse 
en tirete. La stabilisation simultanee dans le temps de ces 
trois parametres n'est pas acquise dans le cas des peuplements 
d'aval de l'Aber Benoit . 

201 



L' accident de l 1 Amoco-Cadiz s'est revele pour nous une expe- 
rience d'ecologie experimentale tout a fait exceptionnelle . Elle 
permet d'apporter des elements de reflexion quant aux mecanismes 
qui mettent en place de telles sequences, probleme pose recemment 
par Connell et Slatyer (1977). 

Dans la succession decrite , les premiers stades correspondent 
a des especes a vie courte , de type opportuniste , capables de sup- 
porter une proportion de matiere organique encore import ante dans 
les sediments . Cette premiere phase de recolonisation par substitu- 
tion est mieux expliquee par les caracteristiques biologiques des 
especes en cause que par quelque propriete emergente de la commu- 
naute toute entiere (Sousa, 1980). Si ces premieres especes ne faci- 
litent pas le retour des especes caracteristiques des stocks ulte- 
rieurs (modele de facilitation), il leur est difficile d'inhiber la 
reapparition des especes a strategie differente qui s'installent plus 
lentement , mais de facon plus durable. Les phenomenes de competition 
existant , peu a peu les premieres especes disparaissent . Ce type de 
succession secondaire peut correspondre au modele de tolerance de 

Connell et Slatyer, dont il n'existe jusqu'ici que peu d'exemples 
connus . Les premieres etapes ont done ete relativement rapides, pour 
les suivantes e'est plus long. La reconstitution, si elle est quali- 
tative, doit aussi etre quantitative, energetique. 

L'approche que nous avons developpee semble plus efficace que 
l f etude dynamique de certaines populations. Elle s'est inspiree de 
la recherche des indicateurs biologiques bien connus en milieu ter- 
restre et d'eau douce. Merne si les parametres ecologiques abiotiques 
semblent normaux, ces bioindicateurs peuvent reveler des perturba- 
tions dans les ecosystemes , qu'il est impossible de detecter par une 
analyse des parametres physiques. 



REFERENCES CITEES 

Aelion, M. et Y. Le Moal , 1981, Impact ecologique de la maree noire 
du "Tanio" sur les plages de Tregastel (Bretagne nord-occiden- 
tale) : Rapport Contrat CNEXO , n° 80/6295 

Bellan, G., Bellan-Santini D. et J. Picard, 1980, Mise en evidence 
des modeles ecobiologiques dans des zones soumises a perturba- 
tions par matieres organiques : Acta Oecologica , Oecol. Applic , 
vol. 3 (3), pp. 383-390 

Cabioch, L., Dauvin J.C., Mora-Bermudez J. et C. Rodriguez-Babio , 
1980, Effets de la maree noire de 1' "Amoco-Cadiz" sur le ben- 
thos sublittoral du nord de la Bretagne : Helgolander wiss . 
Meeresunters. , vol. 33 (1-4), pp. 192-208 

Chasse, C, 1978, Impact ecologique dans la zone cotiere concernee 
par la maree noire de 1 '"Amoco-Cadiz" : Mar. Poll. Bull., 
vol. 11, pp. 298-301 

Chasse, C, L'Hardy-Halos M.T. et Y. Perrot , 1967, Esquisse d'un bi- 
lan des pertes biologiques provoquees par le mazout du "Torrey- 
Canyon" : Penn ar Bed, vol. 6 , pp . 107-112 

202 



Connell, J.H. et R.O. Slatyer, 1977, Mechanisms of succession in na- 
tural communities and their role in community stability and or- 
ganisation : The Amer. Naturalist., vol. 3 (982), pp. 1119-1144 

Gentil, F. et L. Cabioch, 1979, Premieres donnees sur le benthos de 
l'Aber Wrac'h (Nord-Bretagne ) et sur 1' impact des hydrocarbures 
de 1 ' "Amoco-Cadiz" : J. Rech. Oceanogr., vol. IV (1), pp. 35 

Glemarec, M. et C. Hily, 1981, Perturbations apportees a la macro- 
faune benthique de la baie de Concarneau par les effluents ur- 
bains et portuaires : Acta Oecologica, Oecol . Applic . , vol. 3, 
pp. 139-150 

Glemarec, M., C. Hily, E. Hussenot , C. Le Gall et Y. Le Moal , 1981, 
Recherches sur les indicateurs biologiques en milieu sedimen- 
taire marin : Colloque "Recherches sur les indicateurs biolo- 
giques", A.F.I.E., Grenoble 

Glemarec, M. et E. Hussenot, 1981, Definition d'une succession eco- 
logique en milieu meuble anormalement enrichi en matiere orga- 
nique a la suite de la catastrophe de 1' "Amoco-Cadiz" : In 
"Amoco-Cadiz, Consequences d'une pollution accidentelle par 
les hydrocarbures", CNEXO Ed., pp. 499-512 

Le Moal, Y. , 1981, Ecologie dynamique des plages touchees par la 

maree noire de 1' "Amoco-Cadiz" : These 3e cycle, Universite de 
Bretagne Occidentale , 131 pp. 

Le Moal, Y. et M. Quillien-Monot , 1981, Etude des populations de la 

macrofaune et de leurs juveniles sur les plages des Abers Benoit 
et Wrac'h : In "Amoco-Cadiz, Consequences d'une pollution acci- 
dentelle par les hydrocarbures", CNEXO Ed., pp. 311-326 

Marchand, M., 1981, Bilan du Colloque sur les consequences d'une pol- 
lution accidentelle par les hydrocarbures : In Rapport Scient . 
et Techn., CNEXO, 44, pp. 1-86 

Marchand, M. et M.R. Caprais, 1981, Suivi de la pollution de 1' "Amoco- 
Cadiz" dans l'eau de mer et les sediments marins : In "Amoco- 
Cadiz, Consequences d'une pollution accidentelle par les hydro- 
carbures", CNEXO Ed., pp. 23-54 

Pearson, T.H. et R. Rosenberg, 1978, Macrobenthic succession in rela- 
tion to organic enrichment and pollution of the marine environ- 
ment : Oceanogr. Mar. Biol. Ann. Rev., vol. 16, pp. 229-311 

Sousa, W.P., 1980, The responses of a community to disturbance : the 
importance of successional age and species' life histories : 
Oecologia (Berl.), vol. 45, pp. 72-81 



Ce travail a ete realise avec l'aide financiere de la N.O.A.A. 
(Contrat C.N.E.X.O. 79/6180). II a fait partiellement l'objet 
d'une communication presentee au 16eme European Marine Biology 
Symposium de Texel, Septembre 1981. 

203 



LES EFFETS DES HYDROCARBURES DE L 1 AMOCO-CADIZ 
SUR LES PEUPLEMENTS BENTHIQUES DES BAIES DE 
MORLAIX ET DE LANNION D'AVRIL 1978 A MARS 1981 

par 
Louis CABIOCH 1 , Jean-Claude DAUVIN 1 , 
Christian RETIERE 2 , Vincent RIVAIN 2 , 
et Diane ARCHAMBAULT 3 , 



1) Station Biologique de Roscoff, 29211, Roscoff, France 

2) Laboratoire Maritime de Dinard, 35801, Dinard, France 

3) Universite de Laval, Quebec. 



1) INTRODUCTION 

Les premieres nappes d'hydrocarbures de 1 'Amoco-Cadiz atteignent 
le littoral de la region de Roscoff et les cotes orientales de la baie 
de Morlaix le 21 mars, quatre jours apres l'echouage du petrolier sur 
les roches de Portsall. Alors que les masses d'eau chargees en hydro- 
carbures plus toxiques transitent rapidement sur 1 'ensemble de la re- 
gion, des particules oleosedimentaires contaminent les fonds sublitto- 
raux. Elles se deposent preferentiellement dans les zones calmes et 
forment localement des poches de mazout residuel; en baie de Morlaix, 
on note leur presence le 3 avril dans les sables fins peu envases de 
la Pierre Noire par 20 metres de profondeur et le 13 avril dans les 
chenaux des rivieres de Morlaix et de Penze (CABIOCH et al., 1978). 
Durant la meme periode ce phenomene est observe par MARCHAND etCAPRAIS 
(1981) en baie de Lannion. 

La connaissance de la composition et de la distribution des com- 
munautes benthiques de cette region depuis 1968 (CABIOCH) et celle de 
la dynamique du peuplement des sables fins de la Pierre Noire engagee 
depuis 1977 (DAUVIN, 1979) permettent une meilleure evaluation des 
consequences de la pollution sur le macrobenthos subtidal. 

Ces etudes, financees par la NOAA (contrat 78/5830, 80/6145), 
entreprises immediatement apres la catastrophe, ont deja fait l'objet 
de publications : DAUVIN (1979 a, b et sous presse) , CABIOCH et al. 
(1980, 1981 et sous presse) . 



2) LES PEUPLEMENTS ETUDIES 

En Manche les sequences bio-sedimentaires sont principalement sous 
le controle de l'intensite des courants de maree; en consequence del 'en- 
tree vers le fond des baies, les peuplements des sediments grossiers 
sont progressivement relayes par des peuplements de sediments fins plus 
ou moins envases. 

Certains termes de cette sequence ont une distribution spatiale 
discontinue; tel est le cas des peuplements des sables tins separes par 
de vastes etendues de nature differente. 

205 



Les unites cenotigues correspondant aux principaux maillons de 
cette succession bio-sediraentaire ont ete regulierement echantillon- 
nees : 

- les sables gross iers a Venus fasciata - Amphioxus lance- 
olatus de la baie de Morlaix (au large de la Pointe de Primel; carte 
1, P.P.), peu classes avec pour mode la classe 1000 a 5000 microns 
(55 a 70% du sediment total) : releves trimestriels d'aout 1977 a 
aout 1980; 

- le maerl envase de Trebeurden en baie de Lannion (carte 
1, L6), tres peu classe, avec pour mode la classe 250 a 500 microns 
(7 a 58% du sediment total) : releves trimestriels d'avril 1978 a 
mai 1979; 

- les sables fins faiblement envases a Abra alba - Hyalino- 
eaia bilineata des baies de Morlaix et de Lannion (carte 1, P.N., L7, 
L8) , bien classes avec pour mode la classe 125 a 250 microns (42 a 
62% du sediment total) : releves mensuels d'avril 1977 a mars 1981 
(P.N.) et trimestriels d'avril 1978 a fevrier 1981 (L7 et L8) ; 

- les sables tres fins peu vaseux a Tellina fabula - Abra 
alba en baie de Lannion (sous Saint-Ef f lam; carte 1 : Ll, L2, L3, L4 
et L5) , tres bien classes avec pour mode la classe 63 a 125 microns 
(70 a 78% du sediment total) : releves trimestriels d'avril 1978 
a fevrier 1981 sauf L4 d'avril 1978 a mai 1979; 

- les vases sableuses a Abra alba - Melinna palmata de la 
riviere de Morlaix (carte 1 : R.M.) ou domine la classe des parti- 
cules inferieures a 63 microns (47 a 74% du sediment total) accompa- 
gnee d'une importante fraction de sables tres fins et fins : releves 
trimestriels d'aout 1977 a fevrier 1981. 

Les stations de la baie de Morlaix ont ete etudiees par J.C. 
DAUVIN depuis 1977; Ch. RETIERE et V. RIVAIN ont observe les stations 
de la baie de Lannion avec la contribution de D. ARCHAMBAULT pour 1' 
etude de la fin du 3ieme cycle annuel. L" echantillonnage a ete effec- 
tue parallelement au moyen d'une benne Smith Mc Intyre et d'une benne 
Hamon (releves : 10 prelevements a la benne Smith Mc Intyre et 4 ou 
5 a la benne Hamon; surface echantillonnee lm 2 ou plus ) ; le tamisage 
a ete realise sur une maille circulaire de 1mm. 



3) RESULTATS 

Nous avons suivi 1' evolution des parametres ecologiques richesse 
specifique, densite et biomasse. Les richesse specifique et densite 
sont actuellement connues pour la totalite des sites et jusqu'au prin- 
temps de 1981. II en est de meme pour les biomasses relatives aux 
stations de Primel et de la riviere de Morlaix; par contre a la Pierre 
Noire elles ont ete mesurees entre avril 1977 et novembre 1978, puis 
calculees pour les autres releves ; elles n'ont pas encore ete quanti- 
fiees pour les stations de la baie de Lannion. 



3.1) Caractere du stress 

Les effets du stress n'ont pu etre evalues ayec precision que sur 

206 







Ha» 



Carte 1 - Repartition des stations d'echantillonnages en baie de Morlaix et en baie 
de Lannion. 



A 

B - C 



D - E 



Gal 



fonds rocheux 

communaute des sediments grossiers a Amphioxus - Venus fasciata, 
relativement independante de l'etagement (C : facies d'epifaune 
a Sabellaria spinulosa) . 

communaute du maerl (D : facies a Lithothamnium corallioides var. 
corallioides; E : facies a L. covaltioxd.es var. minima] . 

communaute des sables dunaires fins a Abra prismatica- Glycymeris 
glycymeris. 

communaute des sediments fins a Abra alba (G : facies sableux a 
Hyalinoecia bilineata; H : facies envase a Melinna palmata; 
I : facies heterogene envase a Vista cvistata ) . 

communaute des cailloutis et graviers prelittoraux cotiers : 
facies a Ophiothrix fragilis et a Bryozoaires dominants dans 
1 ' encroutement . 



communaute des cailloutis et graviers prelittoraux du large : 
facies d ' ensablement a Porella conoinna. 

207 



les peuplements de la baie de Morlaix pour lesquels nous disposions 
d' observations juste avant la pollution. 

Richesse specif ique. (fig. 1) 

-<- Cycle normal— ►-« 1°Cycle ►-« 2°C y cle — 

N.especes 



-yd 



100- 



50- 



A.C 




J A i 

1 977 



y V "A 'J' A" 'O' 'Dl 
1978 



' A' 'O' 'Dl 
1979 



TTT 



^rv 



1980 



Figure 1 - Peuplement des sables fins a Abra alba - Hyalinoecia bilineata : evolution 
de la richesse specifique des releves (4 prelevements a la benne Hamon) 
d'avril 1977 a fevrier 1981 (A.C. : debut de la pollution par les hydro- 
carbures de 1 '"Amoco Cadiz"). 



A la Pierre Noire la richesse specifique totale passe de 8 <> es- 
peces le ler mars a <ii le 3 avril; cette brusque diminution est due 
pour une grande part a une forte reduction du nombre d'especes d'am- 
phipodes (20 le 18 Janvier, 24 le ler mars, 10 le 3 avril et 7 le 25 
avril) . 

Par contre dans les peuplements de Primel et de la riviere de 
Morlaix la richesse specifique totale se maintient, la chute du nombre 
d'especes d'amphipodes etant compensee par 1 'accroissement concomitant 
de celui des polychetes. 

Les effets du stress sur le groupe des amphipodes sont d'autant 
plus intenses que les especes avaient, avant la pollution un haut de- 
gre de Constance dans le peuplement; ils concernent les especes sui- 
vantes : 

Riviere de Morlaix 



Pierre Noire 
Ampelisca armoricana 



Ampelisaa armoricana 
Ampelisca brevicornis 



Ampelisaa tenuicornis 



Ampelisca bvevicovnis 

Ampelisca spinipes 

Ampelisca tenuicornis 

Ampelisca typica 

Cheirocratus intermedins Cheirocratus intermedins 

Photis longicaudata 

Pariambus typicus 

Corophium cvassicome 

Melita obtusata 

Melita gladiosa. 

Megaluropus agilis 

Ampelisca spinimana 
208 



Primel 
Ampelisca armoricana 

Ampelisca spinipes 



Des 1972, les travaux de SANDERS et al. ont mis en evidence le 
caractere d'especes "tests" que pouvaient presenter les amphipodes 
vis-a-vis de ce type de pollution. Dans le meme esprit les etudes ex- 
perimentales de LINDEN (1976), LEE, WELCH et NICOL (1977), LEE et NICOL 
(1978a et b) ont montre l'extreme sensibilite des amphipodes aux hy- 
drocarbures. Cette sensibilite est confirmee par les observations in- 
situ de SANDERS et al. (1980), DEN HARTOG et JACOBS (1980), ELKAIM 

(1980) et ELMGREN et al. (1980) relatives aux marees noires de West 
Falmouth en 1969 aux Etats-Unis, de l 1 Amoco-Cadiz sur les cotes de Bre- 
tagne et de la Tresis en mer Baltique. 

Cependant des recherches de CABIOCH et al. en baie de Morlaix 

(1981) il ressort que certaines especes appartenant a d'autres groupes 
zoologiques reagissent plus ou moins intensement aux effets du stress; 
il en est ainsi des polychetes Phyllodoae kosteriensis, Terebellides 
stroemi et de nombreuses especes de micro-mollusques . Les fortes morta- 
lites subies, en baie de Lannion, par les populations de mollusques, 
surtout celle de Pharus legumen et de l'oursin Echinocavdium covdatum, 
viennent a l'appui de ces observations. II convient de noter , qu'en 
regie generale, ce sont les annelides polychetes qui constituent le 
noyau d'especes le plus resistant (tabl.i ). 

L' amplitude du stress est done fonction de la composition origi- 
nelle des peuplements et varie fortement d ' une unite cenotique a 1 ' au- 
tre. 

Densites et biomasses 

Les travaux de DAUVIN montrent qu'a cet egard les effets du stress 
sont particulierement devastateurs sur les peuplements de sables fins de 
la Pierre Noire (1979). Les densites passent de 8707 a 1808 individus 
par m 2 et la biomasse de 5.0 a 2.5 g. par m 2 soit une reduction respec- 
tive de 80 et 50 % des valeurs initiales; elle est essentiellement due 
a 1' elimination des ampeliscides AmpeKsca armoricana et Ampelisaa te- 
nuiaornis et a la diminution des effectifs des populations d 1 Ampelisaa 
sarsi . Ces trois especes representaient a elles seules 90 a 99 % des 
densite et biomasse moyennes annuelles du peuplement. (fig . l) 

Sur les peuplements des sables grossiers de Primel et des vases 
sableuses de la riviere de Morlaix, les effets du stress, en terme de 
densite et de biomasse, sont peu marques. 

En conclusion, il apparait clairement que les effets du stress 
sont selectifs au niveau : 

- des especes et groupes zoologiques : les amphipodes et 
plus specialement les ampeliscides se revelent extremement sensibles; 

- des peuplements : la communaute inf ralittorale des sables 
fins a Abra alba - Hyalinoecia bilineata est la plus intensement pertur- 
bee. 



3.2) Evolution a long terme des peuplements. 

Les peuplements des sediments fins sablo-vaseux subissent les per- 
turbations les plus significatives; dans cet expose, 1' etude de leur dy- 
namique fera done l'objet d'une attention toute particuliere. 

209 



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■ W 'J' " s' W | j' M W ' J"sf V IJ 1 M M 'j' 'sf V |j' W W 'J' 's' 'n' Ij' 'M 

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'igure 2 - Peuplement des sables fins a Abra alba - Hyalinoecia bilineata de la Pierre 
Noire : evolution de la densite totale d'avril 1977 a fevrier 1981 avec mise 
en evidence de la part des trois especes d' Ampelisaa tres dominantes (A. a. : 
Ampelisca avmovioana ; A.s. : Ampelisaa sarsi; A.t. : Ampelisaa tenuiaornis) . 
(A.C. : debut de la pollution par les hydrocarbures de l'"Amoco Cadiz"). 



3.2.1) Peuplement des sediments grossiers a Venus fasaiata - Amphioxus 
lanceolatus . 

Pollution (tabl. 2 ) 

Des le 27 avril les sediments sont contamines par les hydrocarbu- 
res; aux fortes teneurs enregistrees jusqu'en novembre (231 ppm) suc- 
cede, en fin d'hiver, une phase de depollution rapide. 

Richesse specifique (fig. 3) 

Le flechissement des valeurs de la richesse specifique au cours 
du premier cycle annuel suivant la pollution semble surtout lie a la 
disparition de crustaces et de polychetes; cependant, de 1978 a 1980, 
on note globalement, abstraction faite des fluctuations saisonnieres, 
un accroissement graduel auquel contribuent largement les amphipodes 
(48 taxons en aout 1978 contre 80 en aout 1980; 4 especes d' amphipodes 
en aout 1978 contre 19 en aout 1980) . 



Densites et biomasses 



Les densites tres faibles varient de 100' a 290 individus par m 2 ; 
maximales en aout, minimales en fevrier, les valeurs sont du meme or- 
dre de grandeur d'une annee a 1' autre. 

211 





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n. individus 



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Dl 



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1977 



'j' 'a' 'o' 'dI V 'A' 'J' 'a"o' 'Ol V 'A' 'J' 
1978 1979 1980 



1000 



500 



Figure 3 - Peuplement des sables grossiers a Venus fasciata - Amphioxus lanceotatus : 
evolution de la richesse specif ique des releves et du nombre d' individus 
(10 prelevements a la benne Hamon) d'aout 1977 a aout 1980 (A.C. : debut de 
la pollution par les hydrocarbures de l'"Amoco Cadiz"). 

Les biomasses des differentes composantes faunistiques sont tres 
inegales; par exemple, le lamellibranche Glyoymeris glyoymeris repre- 
sente 75 % de la biomasse totale du peuplement. Apres avoir depasse 
25 g. par m 2 en aout et novembre 1977, les valeurs n'oscillent ensuite 
qu'entre 8 et 12 grammes. Toutefois en novembre 1979, a la suite d'une 
recolte plus importante de Glyoymeris glyoymeris, elle culmine a pres 
de 24 g. par m 2 rejoignant les valeurs donnees par HOLME (1953) et 
RETIERE (1979) pour des peuplements analogues de la Manche occidentale. 



3.2.2) Peuplement de maerl envase 

Pollution 

La texture heterogene des sediments a favorise le piegeage et la 
retention des particules oleosedimentaires pendant -une longue periode. 



Richesse specifique 

Cette biocenose definie par CABIOCH (1968) comme un maerl a 
Lithothamnium corallioides a evolue vers un nouveau facies, vraisembla- 
blement sous l'effet d'un ensablement lie a des extractions industriel- 
les; elle est actuellement tres comparable a celle du maerl de Ricard, 
en baie de Morlaix : maerl a Lithothamnium oorallioides var. minima. 
Le caractere cenotique dominant est son extreme appauvrissement; aucune 
espece d'epifaune sessile n'est en effet presente dans nos echantillons 
preleves apres la pollution, ce qui atteste sans doute une profonde 

perturbation. 

213 



Nous n'avons recolte dans ces fonds qu'un petit nombre d' especes 
de l'endofaune. On passe toutefois de 23 especes en avril 1978 a 34 
en fevrier 1979 et parmi les plus abondantes il convient de citer trois 
annelides polychetes : Goniada maculata, Staurooepnalus kefersteini, 
Heteromastus filiformis et deux peracarides : Nototropis swammerdani et 
Periooulodes longimanus. De plus il faut noter que les deux especes 
electives du facies heterogene envase, Sthenelais boa et Vista cristata, 
presentes dans les echantillons d'avril 1978, ont ensuite disparu. 



Densites 

L'evolution de la densite globale du peuplement reflete principa- 
lement celle de quelques populations d' annelides polychetes, en par- 
ticulier Goniada emerita et Staurooephalus k efersteini dont les re- 
crutements surmaille de 1 mm s'observent de facon synchrone en au- 
tomne . La premiere espece benef icierait de la proximite de biotopes 
servant de "reservoirs" a partir desquels se realiserait la disper- 
sion des larves pelagiques. 

En conclusion il est important de rappeler que depuis 1968, le 
peuplement macrobenthique de ces fonds a evolue, vraisemblablement 
sous l'effet d'un ensablement lie a 1' extraction du maerl. Ne dis- 
posant d'aucun etat de reference juste avant la catastrophe il est 
extremement difficile de connaitre la part qui revienta la pollution 
par les hydrocarbures, dans la modification de cette communaute. Pour 
cette raison son suivi ecologique a ete rapidement abandonne. 



3.2.3) Peuplements des sediments fins a Abra alba 

3.2.3.1) Peuplement des sables fins a Abra alba - Hyalinoecia bilineata 

Pollution 

Apres une phase initiale de forte pollution, que nous n'avons pu 
mesurer, les teneurs en hydrocarbures (mesurees en spectrophotometrie 
aux infra-rouges, exprimees en mg par kilogramme de sediment sec ou 
ppm) atteignent 1000 ppm a la station L8 au cours de l'ete 1978 alors 
qu'elles ne depassent pas 50 ppm aux deux autres stations (L7 et P.N.), 
puis elles diminuent fortement au cours de l'automne dans 1' ensemble 
des stations. Ensuite une remobilisation, lors des tempetes automnales 
et hivernales, des stocks d'hydrocarbures pieges en zone intertidale 
entraine une augmentation des teneurs en hydrocarbures au printemps 
1979 sur 1' ensemble des stations, (ces teneurs depassent 200 ppm a la 
station de la Pierre Noire) ; elles decroissent rapidement ensuite, sauf 
en L8 ou elles se maintiennent a des valeurs voisines de 100 ppm jus- 
qu'a l'automne 1979. Enfin, dans l'ensemble des stations, apres une 
phase de recontamination au cours de l'hiver 1979-1980, les teneurs de- 
viennent inferieures a 50 ppm a partir de mai 1980. 

Richesse specifique 

Apres le stress on note dans les trois stations un enrichissement 
progressif en especes qui aboutit en 1980, a la Pierre Noire, a des va- 

214 



leurs du meme ordre qu'avant la pollution. Cette remontee provient 
d'une part de la reapparition d'especes eliminees lors du stress, d'au- 
tre part de 1* augmentation de la frequence de quelques especes de poly- 
chetes et de raollusques. Les memes phenomenes s 'observent en baie de 
Lannion (L7 et L8) , mais avec des valeurs inferieures. La comparaison 
des presences d'especes dans les trois stations apporte a cet egard des 
informations signif icatives dans le cas des amphipodes, groupe le plus 
affecte par le stress initial. 

Certaines especes, qui ont survecu en baie de Morlaix, sont 
absentes en baie de Lannion immediatement apres la maree noire, 
mais elles y apparaissent au cours du premier cycle annuel suivant 
le stress (Leuaothoe incisa, Urothoe grimaldii, Tryphosites lon- 
gipes, Bathyporeia tenuipes) , du deuxieme cycle (Ampelisca sarsi) 
ou du troisieme (Bathyporeia elegans, Synohelidium maculatum) .Cet- 
te constatation temoigne de leur presence probable en baie de Lan- 
nion avant la pollution et renforce l'hypothese d'une plus grande 
intensite de 1' impact initial dans cette baie par rapport a la 
baie de Morlaix (CABIOCH et at., 1981) . 

Des especes eliminees temporairement par le stress en baie de 
Morlaix et qui s'y reinstallent au cours du premier cycle pertur- 
be (Megaluropus agilis, Ampelisca spinipes) ou de deuxieme (Chei- 
rocratus intermedins) (DAUVIN, 1981) ne sont rencontrees dans les 
sables fins plus lonquement pollues de la baie de Lannion qu'au cours 
du troisieme cycle. Ces introductions comme les precedentes, inter- 
viennent generalement plus tot en L7 qu'en L8, station la plus pol- 
lute des deux. 

Les especes dont on est certain de 1 ' "insularite" figurent 
parmi celles qui se reinstallent plus tardivement dans l'une ou 
1' autre des baies (Ampelisca tenuicornis 3 A. brevicornis, A. ar- 
moricana) ou qui n'ont pas encore reapparu (Photis longicaudata) . 
A 1' oppose, Ampelisca spinipes, espece non insulaire, commune 
dans les sables grossiers avoisinant la zone polluee, repeuple les 
sables fins de la Pierre Noire des le premier cycle. 

En conclusion, les effets eliminateurs du stress, plus ou 
moins accuses selon les localites d'un meme type de peuplement sem- 
blent accompagnes de reimplantations d'autant plus tardives que la 
pollution residuelle du sediment est durable et intense. La con- 
jugaison de 1' insularite geographique des populations de certaines 
especes et de leur mode direct de reproduction a aussi un effet re- 
tardateur . 



Densites et biomasses 

En baie de Morlaix, a la station de la Pierre Noire la densi- 
te moyenne du peuplement passe de 19450 individus par m 2 lors du 
cycle normal a 2135 au cours du premier cycle apres la pollution. 
Cette tres grande difference est le fait de la disparition et de la 
forte reduction d'effectifs de trois especes d' Ampelisca largement 
dominantes avant la pollution. Durant les deuxieme et troisieme cy- 
cles annuels les densites moyennes atteignent les valeurs respectives 
de 3650 et 4110 individus par m 2 . 

215 



Parallelement a la forte decroissance des densites,la biomasse 
subit une reduction de pres de 50 % pendant le premier cycle annuel 
apres la pollution (4.4 g. par m 2 contre 8.1). Des le second cycle 
elle retrouve des valeurs comparables a celles du cycle normal 
(8.0 g. par m') et les depasse meme au cours du troisieme cycle an- 
nuel (8.7 g. par m 2 ) . 

Ainsi, trois ans apres le stress, bien que les densites soient 
encore inferieures, d'environ 80 %, a celles observees avant la 
pollution, les valeurs de biomasse sont du meme ordre de grandeur que 
celles du cycle normal. En effet les especes subsistant apres le 
stress, dont les densites sont passees de 2100 a 3860 individus par 
m 2 du premier au troisieme cycle annuel apres la pollution, ont des 
poids individuels moyens tres super ieurs a celui des ampeliscides . 

En baie de Lannion 1' evolution de la densite globale du peuple- 
ment est fortement marquee par les variations d'abondance, d'ailleurs 
difficiles a interpreter, d'une seule espece, Paradoneis armata. La 
densite de celle-ci diminue progressivement a la station L8 pour at- 
teindre 500 individus par m 2 en Janvier 1981 et se maintient a un ni- 
veau compris entre 500 et 600 individus par m 2 a la station L7 pendant 
la periode d'observation. II faut toutefois noter qu'au cours des 
trois cycles annuels la densite correspondant a 1 'ensemble des autres 
especes tend a s'accroitre. 

Les reintroductions d'especes temporairement eliminees appor- 
tent tres peu a cette croissance de la densite a moyen terme apres le 
le stress. Elle resulte principalement de quelques cas de £f52lo. n i§5~ 
tion par des especes reduites en effectifs pendant le premier cycle 
perturbe et de P£2life£gtion d'especes non affectees par la pollution. 
Les autres especes poursuivent des cycles annuels peu differents du 
cycle normal. 

Les recolonisations signif icatives sont le fait de trois espe- 
ces : Ampelisca sarsi, Ampharete aoutifrons, Nephtys hombergtt. Alors 
que la communaute des sables fins de la Pierre Noire a pu heberger 
jusqu'a 40.000 Ampelisaa par m 2 , l'espece subsistante, A. sarsi ne re- 
colonise cette vaste niche ecologique vacante qu'a une cadence res- 
treinte (fig. 4) de par la conjonction de sa distribution "insulaire" 
et de ses caracteres biologiques (reproduction directe printaniere et 
estivale, femelles porteuses de 8 a 20 embryons seulement et ne se 
reproduisant qu'une fois, vie breve ne depassant guere un an (DAUVIN, 
1979)). Limitee par 1' insular ite au seul potentiel reproducteur de sa 
population residuelle, l'espece multiplie cependant son effectif ma- 
ximum annuel par un facteur de 5 a 9 d'une annee sur 1' autre ce qui 
temoigne du succes de la reproduction directe. Ampharete aautifrons, 
(fig. 5) insulaire, de duree de vie inferieure a deux ans, a larve 
presque immediatement benthique, suit un schema de recolonisation len- 
te du meme type. Par contre, le repeuplement de Nephtys hombergii 
(vie longue, non insularite, larves pelagiques pendant plus d'un mois) 
s'effectue rapidement (fig. 6); des 1980, les effectifs estivaux, qui 
ne depassaient pas 30 individus par m 2 en 1978, atteignent 170 par in 2 , 
valeur superieure a celle observee avant pollution (90 par m 2 ) . 

En ce qui concerne les proliferations, la breve poussee d' Hete- 
rocirrus alatus a l'automne de 1978 (fig. 7) est suivie, au cours du 
deuxieme et du troisieme cycle par des accroissements importants de 
Chaetozone setosa, (Fig. 7), Spio filioornis, Saoloplos avmiger, 
Thyasira flexuosa, Abra alba. Ainsi se dessine probablement un pre- 
mier element d'une serie de "successions" (PEARSON & ROSENBERG, 
1978) , phenomene moins immediat et moins accuse ici que sur les fonds 
sublittoraux bien plus pollues des Abers (GLEMAREC & HUSSENOT, 1981; 
GLEMAREC & HUSSENOT, sous presse) . 216 



N/m 



10 



10 



10 



10 • 



-* Cycle normals — >~-< TCycle 




Figure 4 - Peuplement des sables fins a Abra alba - Hyalinoecia bilineata de la Pierre 

Noire : evolution de la densite d 1 Ampelisca sarsi d'avril 1977 a fevrier 1981 
(A.C. : debut de la pollution par les hydrocarbures de 1 '"Amoco Cadiz"). 



-*- — CYCLE NORMAL - *••• 

N.m-2 



1'CYCLE 



2'CYCLE »-• 3'CYCIE - •- 



200 . 



100 - 



AC- 




\ \ 
\ 



I \ 

/ \ ' 
/ \ 

' \ 



I 



a 
l\ 

I \ 



'\-l 



I 



\ 



/M\ 



i i i i i i i i i i i 

< M J S M I J 

1977 



■ i rnVV i r r 



'."Fo-r. *• I-*' 



7 AAkZ/ v ~.\ Ll 

J s'- • " v.PN 



I I I I I I I IT I I I I I I I I I I I I I I I I I I I I I I I 

J snIjmvj inIj MMJ $ N Ij 



1978 



1979 



1980 



Figure 5 - 



Peuplement des sables fins a Abra alba - Hyalinoecia bilineata : evo- 
lution de la densite d 1 Ampharete grubei d'avril 1977 a fevrier 1981 
(A.C. : debut de la pollution par les hydrocarbures de l"'Amoco Cadiz") 

217 



-Cycle normal-*-- <- 1°Cycle >— «— 2° Cycle >~< 3°C y cle >- 



N .m 



150- 



100- 



50 - 




rvr 1 W 'J' 's' V ij' M M 'j' 's' 'n' Ij" W M 'j' 's' W Ij' 'm' W 'j' 's' 'n' 'j' 'iW 

1977 1978 1979 1980 



Figure 6 - Peuplement des sables fins a Abra alba - Hyalinoecia bilineata : evolu- 
tion de la densite de Nephtys hombergii d'avril 1977 a fevrier 1981 
(A.C. : debut de la pollution par les hydrocarbures de 1 '"Amoco Cadiz") 



■<j- Cycle norraal->"< 1°Cycle »— < 2°Cycle >— * 3°Cycle 



1000 - 



100 - 




m' tv? 'j' y W Ij' M W '/ 's' ' '*' |j' W W 'j' 's' W |j' 'm' W 'j' 's' W I 'f' 

1977 1978 1979 1980 



Figure 7 - Peuplement des sables fins a Abra alba - Hyalinoecia bilineata : evolu- 
tion schematique de la densite d' Abra alba (A. a.), de Chaetozone setosa 
(C.s.), d' ' Heterocirrus alatus (H.a.), de Scoloplos armiger (S.a.), de 
Spio filicornis (S. f.) et de Thyasira flexuosa (T.f.). (A.C. : debut 
de la pollution par les hydrocarbures de 1 ' "Amoco Cadiz"). 

218 



3.2.3.2) Peuplement des sables tres fins a Tellina fabula - Abra alba 

Pollution 

Les teneurs en hydrocarbures apres un pic passager en aout 1978 
(premieres mesures) redeviennent fortes de fevrier a mars 1979 (valeurs 
comprises entre 80 et 300 ppm) . A la faveur d'une recontamination du 
sediment au cours de l'automne 1979, les teneurs depassent de nouveau 
50 ppm en novembre (70 a 16 5 ppm) elles se maintiennent a ce niveau en 
L2 et L3 au cours de l'hiver 1980, puis redeviennent inferieures a par- 
tir de mars 1980 dans 1' ensemble des trois stations. 



Richesse specifique et densites 4 



On sait indirectement que ce peuplement a subi une perturbation 
considerable lors du stress; les immenses quantites d' Eehinocardium 
oordatum et de mollusques de diverses especes, rejetes rnorts sur la 
greve de St-Efflam en mars-avril 1978 en temoignent (CHASSE & GUENO- 
LE-BOUDER, 1981) . Les phenomenes observes a la suite du stress pre- 
sentent de grandes analogies avec ceux que nous venons de decrire : 
croissance a moyen terme de la richesse specifique (fig. 8) et de la 
densite totale, phenomenes de recolonisation. 



~* CYCLE NORMAL 

N especes 



I'CYCLE 



2'CYCLE 



h 3'CYCLE - »• 



SO. 



25 



AC 




I I I I I r r 

< J I N 



~n i ■ i i i i 



~i r i i r 



T7 



• r i i 
j • 



Figure 8 - 



1977 1978 I9>« 1980 

Peuplement des sables tres fins a Tellina fabula - Abra alba : evolution 
de la richesse specifique des releves (4 prelevements a la benne Hamon) 
d'avril 1978 a fevrier 1981 (A.C. : debut de la pollution par les hydro- 
carbures de 1 '"Amoco Cadiz"). 



*Les resultats du suivi de la station Ll dont le peuplement presente un 
caractere nettement intertidal ne sont pas integres dans ce travail qui 
a pour objet 1' etude des communautes subtidales. De meme le suivi de la 
station L4 a ete abandonne en mai 1979, le depouillement des donnees 
n'apportait pas d' informations complementaires de celles recueillies 
aux stations L3 et L5. 2iq 



La croissance de la densite est principalement liee a la proli- 
feration, depuis la perturbation, du Capitellidae Mediomastus fragilis 
(fig. 9) dont les effectifs a la station L3 passent de 100 individus 
par m 2 en avril 1978 a plus de 7000 par m 2 en mai 1980. 



N.m-2 
10 4 -, 



•m 1'CTCLE 



J'cyci r 



3*CYCLE „ 



10 J - 



10 . 



AC 




I ' i ' 



'l 1 I I I I I 



1978 



i i I i — r 



i i i i — r 
j s 



/L 



1979 



I I I I 1 I 



1980 



Figure 9 - Peuplement des sables tres fins a Tellina fabula - Abra alba : evolution 
de la densite de Mediomastus fragilis d'avril 1978 a fevrier 1981 (A.C. : 
debut de la pollution par les hydrocarbures de l"'Amoco Cadiz"). 

Les recolonisations signif icatives sont ici le fait de trois es- 
peces : Nephtys hombergii, Glycera convoluta et Tellina fabula; mais 
alors que les deux premieres voient leurs effectifs augmenter progres- 
sivement d'annee en annee (respectivement de 63 et 80 individus par 
m 2 en 1978 a 162 et 360 en 1981) 1 ' abondance de Tellina fabula qui n'a 
pas depasse 250 individus par m 2 en 1978 et 1979, s'eleve brusquement 
a plus de 1000 individus par m 2 pendant le troisieme cycle. 



3.2.3.3) Peuplement des vases sableuses a Abra alba - Melinna palmata 

Pollution 

Les teneurs en hydrocarbures sont tres elevees jusqu'en juillet 
1979 (elles depassent toujours 100 ppm sauf en fevrier 1979 et elles 
atteignent meme 3000 ppm en mars 1979) ; ensuite on observe une depol- 
lution graduelle. 



220 



Richesse specifique (fig. 10) 

D'avril 1978 a avril 1980 la richesse specifique est stable; elle 
s'accroit considerablement au cours de l'ete 1980, diminue ensuite et 
se maintient durant l'hiver suivant a un niveau plus eleve que celui 
des hivers precedents. 

L 1 augmentation de la richesse specifique provient a la fois de la 
reintroduction d'especes d'amphipodes eliminees lors du stress et de 
1' accroissement du nombre d'especes de polychetes . 



•m CTCLI nohmai - «»4— 



t'C»CLI - • 



2'CYCll «-• ■ 



- 3'ctcif - •• 



N especes 



1 00 



50. 



AC 



• ■ _. 




i i i i i i i 

w W J s 



1977 



I J M 



I I I I I 

J 

1978 



I J k 



I I I I I I 1 
H J S I 

1979 



T-r 



i i i i i i i i 



1980 



-m 



Figure 10 - Peuplement des vases sableuses a Abra alba - Melinna palmata : evolution 
de la richesse specifique des releves (10 prelevements a la benne Smith 
Mc Intyre) d'aout 1977 a mars 1981. 

Les reapparitions d'amphipodes se realisent de maniere graduelle : 
les premiers exemplaires de Cheirocratus intermedins et Ampelisca 
breviaornis sont recoltes plus d'un an apres leur disparition, ceux 
d' Ampelisca tenuicornis seulement au cours du second cycle; les especes 
Ampelisca armoricana et Ampelisca spinimana n'ont pas encore ete retrou- 
vees. 

En ce qui concerne les polychetes on observe conjointement la cap- 
ture plus frequente d'especes sporadiques avant la pollution et 1' intru- 
sion d'especes constantes, pour la plupart, dans le peuplement des sa- 
bles fins a Abra alba - Hyalinoecia bilineata de la Pierre Noire. 

Densites et biomasses 



La densite qui n'est pas modifiee lors du stress croit au cours du 
premier cycle annuel perturbe : 4467 individus par m.2 en moyenne contre 
2855 durant le cycle normal avant la pollution. Cette difference est due 
essentiellement aux fluctuations d'effectifs d'especes presentes, avant 
la pollution, en densites faibles (Mediomastus fragilis, fig. 12 et 
Tharyx marioniy fig. 13) ou fortes (Chaetozone setosa, fig.il). 

221 



N .m 



Cycle normal 
2 



-1° Cycle 



->—< 



2°Cycle 



->~<- 



3° Cycle- 



6000 



5 000 



4 000 



3 000 



2 000- 



1000 




1979 



1980 



Figure 11 - Peuplement des vases sableuses a Abra alba - Melinna palmata : evolution 
de la densite totale d'aout 1977 a mars 1981 avec mise en evidence de 
la part de Chaetozone setosa (C.s.) (A.C. : debut de la pollution par 
les hydrocarbures de 1 '"Amoco Cadiz"). 

Au cours du second cycle, la densite redevient voisine de celle du 
cycle normal, puis augmente a nouveau durant le troisieme cycle : 3724 
individus par m 2 ; cette derniere valeur s'explique par le haut niveau 
d'abondance de Mediomastus fragilis et Tharyx marioni, par une elevation 
de la densite d'autres especes de polychetes notamment Lanice conohilega 
et Melinna palmata et enfin par la recolonisation de Nephtys hombergii 
et Ampelisaa tenuicovnis . 



— - CYCLE NORMAL- «--• I* CYCLE »--. 2'CYCLE 

,-2 



3'CYCLE - •- 



io a 



250 . 



A-C- 




i i i i i 

* J s 
1977 



I I I I 1 I I I I I I I I I I 

Mj snIjmuj 

1978 1979 



I I I TT I I I I 1 I I I | 

S N I J M U.J S 

1980 



Figure 12 - Peuplement des vases sableuses a Abra alba - Melinna palmata : evolution 
de la densite de Mediomastus fragilis d'aout 1977 a fevrier 1981 (A.C. : 
debut de la pollution par les hydrocarbures de 1 '"Amoco Cadiz"). 

222 



-• CYCLE NORMAL 

N.m-2 
300^ 



250 



I'CYCLE 



2*CYCLE 



TCYCLE «- 



200- 



150 



100 



50 



/ 



A-C. 




' ' i i i ' ' ■ I n i r i i i i i i i [ t i i i i i i i i i i r i i i i i i i i i i i i i i 

■' * 1 S H I J M M J InIjUUJ t m I j UMJ ( m I j 



1177 



1978 



' 3 .'9 



{'ISO 



Figure 13 - Peuplement des vases sableuses a Abra alba - Melinna palmata .- evolution 
de la densite de Tharyx mavioni d'aout 1977 a fevrier 1981 (A.C. : debut 
de la pollution par les hydrocarbures de 1' "Amoco Cadiz"). 



L 1 accroissement des biomasses moyennes correspondant aux quatre 
cycles annuels d 'observations est lie surtout a 1' installation progres- 
sive de Lanice conchilega dans le peuplement. De 1977 a 1980 les valeurs 
relatives aux observations effectuees entre les mois d'aout et avril 



sont respectivement 9.0, 



13.0 et 12.4 



g. par m z ; pour la periode 
comprise entre aout 1980 et mars 1981 la biomasse moyenne atteint 16.8 g. 
par m . 

Les valeurs moyennes de densite (3425 individus par m 2 ) et de bio- 
masse (12.9 g. par m 2 ) s'accordent avec celles donnees par les auteurs 
travaillant sur des peuplements analogues (RETIERE, 1979) . 

Au terme de 1' etude des peuplements de sables fins vaseux il im- 
porte de souligner que les modalites quantitatives des divers pheno- 



223 



menes qui se succedent dans le peuplement a Abra alba - Melinna pal- 
mata de la rade de Morlaix different profondement de celles observees 
dans le peuplement a Hyalinoecia bilineata de la Pierre Noire. Dans 
le oremier, ies especes sensibles aux hydrocarbures sont en effet peu 
representees avant la pollution, si bien que les mortalites initiales 
sont faibles et n'alterent que legerement la structure du peuplement, 
contrairement a la modification structurale considerable intervenue a 
la Pierre Noire. L'evolution ulterieure des deux peuplements a moyen 
et long terme off re un contraste d'une autre nature. La communaute 
subsistante de la Pierre Noire poursuit une dynamique de reconstitu- 
ting dans un milieu benthique rapidement decontamine, et naturelle- 
ment oligotrophe. Au contraire, le peuplement de la rade de Morlaix 
vit dans un milieu benthique naturellement eutrophe, plus durablement 
charge d'hydrocarbures et de matieres organiques. On assiste alors 
a un developpement plus important des populations de detritivores , de- 
ja abondants en conditions naturelles (Chaetozone setosa) et aussi a 
de veritables proliferations d'especes reellement opportunistes (Medio- 
mastus filiformis et Tharyx marioni sp.), presentes seulement a l'etat 
latent au cours du cycle normal precedant la pollution. 



4) CONCLUSIONS GENERALES 

Le recul qu'apportent trois annees d' observations permet de distin- 
guer parmi les phenomenes qui ont affecte les peuplements subtidaux de 
la region de Roscoff ceux lies au stress proprement dit de ceux qui se 
sont succedes au cours des cycles annuels suivants et d'en interpreter 
les differentes modalites : 

- 1' elimination des especes lors du stress est selective; 
elle est fonction a la fois de 1 ' eco-ethologie des especes et des con- 
centrations du milieu en hydrocarbures toxiques dissouts. Cette phase 
de mortalite est relativement limitee dans le temps (quelques semaines); 

- l'intensite des perturbations dues au stress varie d'une 
communaute a 1' autre le long du gradient edaphique et a 1' inter ieur 

de la mime unite de peuplement. Alors que les peuplements des sedi- 
ments grossiers et des sables vaseux ont ete peu modifies qualitative- 
ment et quantitativement par le stress, ceux des sables fins et tres 
fins ont ete intensement perturbes. Ces divers degres d' alteration 
sont fonction du nombre et de l'abondance des especes sensibles aux 
hydrocarbures; dans le cas extreme du peuplement des sables fins a 
Abra alba - Hyalinoea-ia bilineata on assiste a une reduction respecti- 
ve de 80 et 50 % des valeurs initiales de densite et de biomasse. Tou- 
tefois il convient de noter que ce n'est pas necessairement sur le peu- 
plement ou le stress a ete le plus devastateur que les effets secondai- 
res sont les plus marques; 

- dans les biotopes ou les effets du stress se sont faits 
sentir severement les valeurs de la richesse specifique, de la densite 
et de la biomasse restent faibles pendant le premier cycle annuel apres 
la pollution; on n'enregistre pas, au cours de cette periode, de morta- 
lites massives d'adultes mais 1' absence de recrutement chez un certain 
nombre d'especes freine considerablement la recolonisation du milieu. 
Dans la plupart des cas, durant cette premiere phase, les effets sont 

224 



propor tionnels aux quantities d'hydrocarbures residuels; 

- le deuxieme cycle annuel marque globalement le debut de 
la reintroduction des especes eliminees et de la recolonisation des 
fonds par celles dont les populations ont ete affectees par le stress. 
Ces phenomenes s'accelerent et s'accentuent au cours du troisieme cy- 
cle. La vitesse de reintroduction et le taux de recolonisation de 
certaines d'entre elles sont d'ailleurs limites par le caractere insu- 
laire de leur distribution et l'absence de phase pelagique; 

- les cycles de densite de la plupart des especes qui n'ont 
pas ete affectees par le stress se deroulent a peu pres normalement; 
par contre un petit nombre d' especes regroupant surtout des Cap-itelli- 
dae et Cirratulidae proliferent soit au cours du premier cycle, soit 
plus tardivement, constituant probablement les amorces d'une succes- 
sion ecologique; 

- trois ans apres la pollution par les hydrocarbures la ri- 
chesse specifique du peuplement le plus perturbe , c'est-a-dire celui 
des sables fins peu envases, a retrouve son niveau initial et bien que 
sa densite soit toujours beaucoup plus faible qu'elle ne l'etait aupa- 
vant les valeurs de biomasse sont a nouveau tout a fait comparables a 
celles de 1977. II semble done que ce peuplement evolue vers un "nou- 
vel equilibre"; 

En outre, de cette etude se degagent un certain nombre d'enseigne- 
ments : 

- les cartes bio-sedimentaires, support des etudes dynami- 
ques, constituent un etat de reference dont l'interet est evident dans 
le cas de pollutions accidentelles du type "Amoco-Cadiz" ; 

- sur 1' ensemble du secteur touche par la pollution les 
premieres investigations doivent etre engagees tres rapidement; au sein 
des communautes presumees les plus sensibles il est indispensable de 
selectionner plusieurs stations, le suivi de certaines d'entre elles 
pouvant etre abandonne a la lumiere des premiers resultats; 

- le suivi ecologique doit s'etaler sur une periode suffi- 
samment longue pour qu'au dela du bruit de fond des fluctuations natu- 
relles a plus ou moins long terme on puisse percevoir les phenomenes 
reellement dependants de la perturbation. 



225 



BIBLIOGRAPHIE 



BESLIER, A., J.L. BIRRIEN, L. CABIOCH, C. LARSONNEUR S L. IE BORGNE, 19B0. La 
pollution des baies de Morlaix et de Lannion par les hydrocarbures de 
1' "Amoco Cadiz" : repartition sur les fonds et evolution. Helgoland, 
wiss. Meeresunters, Vol. 33, pp. 209-224. 

BESLIER, A., 1981. Les hydrocarbures de 1' Amoco Cadiz dans les sediments sublitto- 
raux au nord de la Bretagne. Distribution et evolution. These 3eme 
cycle Geologie, Universite de Caen, 204 pp. 

CABIOCH, L.1968. Contribution a la connaissance des peuplements benthiques de 
la Manche occidentale. Cah. Biol, mar., Vol. 9, pp. 488-720. 

CABIOCH, L., J.C. DAUVIN S F. GENTIL, 1978. Preliminary observations on pollution 
of the sea bed and disturbance of sub-littoral communities in northern 
Brittany by oil from the Amoco Cadiz. Mar. Pollut. Bull., Vol. 9, pp. 303-307, 

CABIOCH, L., J.C. DAUVIN, J. MORA BERMUDEZ, C. RODRIGUEZ BABIO, 1980. Effets de 
la maree noire de 1' Amoco Cadiz sur le benthos sublittoral du nord de 
la Bretagne. - Helgoland, wiss. Meeresunters, Vol. 33, pp. 192-208. 

CABIOCH, L., J.C. DAUVIN, F. GENTIL, C. RETIERE & V. RIVAIN, 1981. Perturbations 
induites dans la composition et le f onctionnement des peuplements ben- 
thiques sublittoraux sous l'effet des hydrocarbures de 1' Amoco Cadiz. 
In : Consequences d'une pollution accidentelle par les hydrocarbures. 
Centre National pour 1 ' Exploitation des Oceans, Paris, pp. 513-525. 

CABIOCH, L., J.C. DAUVIN, C. RETIERE, V. RIVAIN & D. ARCHAMBAULT, 1982. Evolution 
a long terme (1978-1981) de peuplements benthiques des fonds sedimentai- 
res de la region de Roscoff, perturbes par les hydrocarbures de 1' Amoco 
Cadiz. Neth. J. Sea Research (sous presse) . 

CHASSE, C. & A. GUENOLE-BOUDER, 1981. Comparaison quantitative des populations 

benthiques des plages de St Eff lam et St Michel-en-Greve avant et depuis 
le naufrage de l'Amoco Cadiz. In : Consequences d'une pollution acciden- 
telle par les hydrocarbures. Centre National pour 1 ' Exploitation des 0- 
ceans, Paris, pp. 513-524. 

DAUVIN, J.C, 1979a. Impact des hydrocarbures de l'Amoco Cadiz sur le peuplement 
inf ralittoral des sables fins de la Pierre Noire (Baie de Morlaix). 
J. Rech. oceanogr.. Vol. 4 (1), pp. 28-29. 

DAUVIN, J.C, 1979b. Recherches quantitatives sur le peuplement des sables fins 
de la Pierre Noire, Baie de Morlaix, et sur sa perturbation par les hy- 
drocarbures de l"Amoco Cadiz". These 3eme cycle Oceanographie Biologique, 
Universite P. & M. Curie, 251 pp. 

DAUVIN, J.C, 1981. Evolution a long terme des populations d'Amphipodes des sa- 
bles fins de la Pierre Noire (Baie de Morlaix) apres 1' impact des hydro- 
carbures de l'Amoco Cadiz. J. Rech. oceanog., Vol. 6 (1), pp. 12-13. 



DAUVIN, J.C, 1982. Impact of Amoco Cadiz oil spill on the muddy fine sand Abra 

alba and Melinna palmata community from the Bay of Morlaix. Estua. coast, 
Shelf Science (in press). 

226 



Den HARTOG, C. 8 R.E.W.H. JACOBS, 1980. Effects of the Amoco Cadiz oil spill on 
an eelgrass community at Roscoff (France) with special reference to 
the mobile benthic fauna. - Helgoland, wiss. Meeresunters, Vol .33 , pp. 182- 

191. 

ELMGREN, R., S. HANSSON, U. CARSSON & B. SUNDELIN, 1980. Impact of oil on deep soft 
bottoms. In : J.J. KINEMAN, R. ELMGREN & S. HANSSON. The Tsesis oil spill 
U.S. Department of Commerce, NOAA, pp. 97-126. 

ELK.AIP1, B., 1981. Effets de la maree noire de 1' Amoco Cadiz sur le peuplement 

sublittoral de l'estuaire de la Penze. In : Consequences d'une pollution 
accidentelle par les hydrocarbures. Centre National pour 1 'Exploitation 
des Oceans, Paris, pp. 527-537. 

GENTIL, F. S L. CABIOCH, 1979. Premieres donnees sur le benthos de l'Aber Wrach 
(Nord Bretagne) et sur 1 ' impact des hydrocarbures de 1' Amoco Cadiz. 
J. Rech. oceanogr.. Vol. 4 (1), pp. 33-34. 

GLEMAREC, M. S E. HUSSENOT, 1980. Definition d'une succession ecologique en mi- 
lieu anormalement enrichi en matieres organiques a la suite de la ca- 
tastrophe de l'Amoco Cadiz. In : Consequences d'une pollution acciden- 
telle par les hydrocarbures. Centre National pour 1 ' Exploitation des 
Oceans, Paris, pp. 499-512. 

GLF-VlAREC, H. & E. HUSSENOT, 1982. Ecological survey for the three years after 

Amoco Cadiz oil spill in Benoit and Wrac'h Abers. Neth. J. Sea Research 
( in press] . 

HOLME, N.A., 1953. The biomass of the bottom fauna in the English Channel off 
Plymouth. J. mar. biol. Ass. U.K., Vol. 32, pp. 1-49. 

LEE, W.J. & J.A.C. NICOL, 1978. Individual and combined toxicity of some petro- 
leum aromatics to the marine Amphipod Elasmopus pectenicrus. Mar. Biol.. 
Vol. 48, pp. 215-222. 

LEE, W.H., M.F. WELCH & J.A.C. NICOL, 1977. Survival of two species of amphipods 
in aqueous extracts of petroleum oils. Mar. Pollut. Bull ..vol .8, pp. 92-94. 

LINDEN, 0., 1976. Effects of oil on the amphipod Gammavus oceanious. Environ. 
Pollut., vol. 10, pp. 239-250. 

MARCHAND, Y\. & V\.P. CAPRAIS, 1981. Suivi de la pollution de l'Amoco Cadiz dans 

1 ' eau de mer et les sediments marins. In : Consequences d'une pollution 
accidentelle par les hydrocarbures. Centre National pour 1' Exploitation 
des Oceans, Paris, pp. 23-54. 

PEARSON, T.H. 8 R. ROSENBERG, 1978. Macrobenthos succession in relation to orga- 
nic enrichment and pollution of the marine environment. Oceanogr. mar. 
Biol. Ann. Rev., Vol. 16, pp. 229-311. 

RETIERE, C, 1979. Contribution a 1' etude des peuplements benthiques du golfe 

normanno-bretcn. These doctorat d'Etat, Sci. Nat., Univ. Rennes,370 pp. 



227 



SANDERS, H.L.. J.F. GRASSLE & G.R. HAMPSON, 1972. The West Falmouth oil spill. 
Woods Hole oceanogr. Instn. Tech. Rep. 1-72-20, 48 pp. 

SANDERS, H.L., J.F. GRASSLE, G.R. HAMPSON, L.S. MORSE, S. GARNER-PRICE S C. JONES, 
1980. Anatomy of an oil spill : long-term effects from the grounding 
of the barge Florida off West Falmouth, Massachusetts. J. mar. Res. , 
Vol. 38, 265-380. 



228 



ETUDE EXPERIMENTALE D'UNE POLLUTION PAR 
HYDROCARBURES DANS UN MICROECOSYSTEME 
SEDIMENTAIRE. I : EPPET DE LA CONTAMINATION 
DU SEDIMENT SUR LA MEIOFAUNE 



par 



Boucher G., Chamroux S., Le Borgne L. 
et Mevel G. 
Station Biologique de Roscoff 29211 (FRANCE) 



RESUME 

Les consequences de deux niveaux de contamination par hydrocarbu- 
res ont ete analysees, par rapport a un temoin, dans des microecosyste- 
mes experimentaux en circuit clos contenant 100 litres de sable fin 
sublittoral. L'evolution des caracteristiques du peuplement de meio- 
faune (Nematodes et Copepodes) a ete choisie pour caracteriser 1 ' im- 
pact des hydrocarbures. Les densites des Nematodes augmentent sensi- 
blement par rapport au temoin pendant les deux premiers mois de la 
pollution puis regressent lentement sans qu'il soit possible de dis- 
tinguer les effets d'une forte pollution de ceux d'une faible pollu- 
tion. Les densites des Copepodes harpacticoides sont d'autant plus 
faibles que le sediment est plus contamine. Le rapport Nematodes/Co- 
pepodes parait etre un indice significatif du degre de pollution. 

La composition faunistique des Nematodes est profondement roodi- 
fiee dans le module le plus pollue apres 3 mois d' experience. Cette 
degradation se manifeste par une chute brutale de la biomasse et de 
la diversite specifique. Des petites especes opportunistes connues 
pour leur association avec 1 ' enrichissement en matiere organique, de- 
viennent dominantes. Le module faiblement pollue ne presente aucune 
degradation interpretable, par rapport au temoin, des parametres du 
peuplement. 



* Ce travail a ete realise avec l'aide d'un contrat n° 80/6189 passe 
entre : le Centre National de la Recherche Scientif ique, le Centre 
National pour 1 'Exploitation des Oceans et la National Oceanographic 
and Atmospheric Agency (USA). II a fait l'objet d'une presentation au 
Seminaire AMOCO CADIZ CNEX0-N0AA : "Bilan des etudes biologiques de 
ta pollution de I' Amoco Cadiz" organise au Centre Oceanologique de 
Bretagne Brest (France) les 28 et 29 octobre 1981. 



229 



INTRODUCTION 



Les consequences des pollutions sur 1 'environnement sont souvent 
diff icilement interpretables car leur dilution dans un milieu complexe 
peut provoquer des alterations .plus ou moins discernables des fluctua- 
tions naturelles, apparaissant immediatement apres contamination ou 
differees dans le temps. 

L' experimentation en laboratoire de la toxicite des polluants 
sur des organismes isoles de leur environnement naturel a montre sou- 
vent ses limites car elle ne prend pas en compte les effets cumulatifs. 
Par contre, les simulations sur des microecosystemes complexes appeles 
microcosmes ou mesocosmes selon leur taille, permettent de mieux cer- 
ner les consequences des perturbations des ecosystemes et souvent de 
completer les observations realisees dans le milieu naturel. L'utili- 
sation des microcosmes permet en outre d'integrer les interactions 
entre les niveaux trophiques d' organisation des ecosystemes par exem- 
ple et de realiser des manipulations et des replications. 

Quelques rares simulations au laboratoire de contaminations par 
hydrocarbures ont jusqu'ici ete realisees soit pour envisager les vi- 
tesses de degradation des hydrocarbures en milieu sedimentaire com- 
plexe (Johnston, 1970; Delaune et coll. 1980; Wade & Quinn 1980) soit 
pour comprendre les effets sur les organismes dans les differents ni- 
veaux d' organisation de l'ecosysteme (Lacaze 1979; Elmgren et coll. 
1980; Grassle et coll. 1981; Elmgren & Frithsen, sous presse) . 

A la suite de la pollution petroliere de 1' "Amoco Cadiz" sur les 
cotes de Bretagne Nord (Manche occidentale) , nous nous sommes attaches 
parallelement a 1 'etude in situ des consequences de la contamination 
des sables fins sublittoraux (Boucher 1980 et 1981; Boucher, Chamroux 
et Riaux 1981), a realiser une simulation du phenomene dans des micro- 
ecosystemes en circuit clos. 



MATERIEL ET METHODES 



Trois modules experimentaux en circuit clos dont le principe a 
ete fourni dans Boucher et Chamroux (1976) ou Mevel (1979) sont uti- 
lises (Figure n° 1). Chaque bac comporte trois compartiments dont les 
niveaux sont regules par contacteur electrique (500 litres d'eau de 
mer du large). Le compartiment principal comporte 100 litres de sable 
reparti sur un double fond sur une surface de 0,41 m 2 et une hauteur 
de 25 cm environ,, et percole par difference de niveau entre les compar- 
timents a une vitesse de filtration de l'ordre de 15 l/m 2 /heure. Le 
sediment est preleve a la benne Smith-Mclntyre en milieu sublittoral 
par - 19 metres de profondeur (Station de la Pierre Noire). Sa media- 
ne est de 136 ± 5 p. La temperature pendant le duree de 1' experience 
a varie entre 10 et 15°C. Les trois mesocosmes ont ete nourris tous 
les deux jours par des casaminoacides de DIFCO a des doses correspon- 
dant a 50 g d'Azote/an/m 2 . 

L'un des problemes importants a resoudre etait le mode d' intro- 
duction des hydrocarbures dans les modules experimentaux. Respective- 
ment 100, 10 et g. d 'hydrocarbures Arabian light»etetes a 240°C > 

230 



I. 



Pump2 

Pumpl 



HL_Q 






I 






§ 



,1 



i I 

1 ■ 




* Water 500 1. 

Lsulslqasulqasul/ 



rid iqo I. 



I 



cooler 




amplifier 
pH_rH 



recorder 
pH_rH 



0,66x0, 98m = 0, 41 m 2 



FIGURE 1. Schema d'un bac experimental ou mesocosme utilise pour les 
simulations de pollution par hydrocarbures (Volume de sable 
100 litres, Volume d'eau : 500 litres). 



(fournis par l'IFP) ont ete melanges a 1 kg de sable sec et homogenei- 
ses avec 100 ml de tetrachlorure de Carbone. Apres evaporation totale, 
le sediment ainsi traite a ete ajoute respectivement dans chacun des 
trois modules appeles : Bac fortement pollue, Bac faiblement pollue 
et Temoin. Le coulage des hydrocarbures a ete ainsi quasi immediat et 
l'essentiel des particules contaminees s'est reparti a la surface du 
substrat. Une faible fraction est restee a la surface de l'eau conte- 
nue dans le compartiment a sable du bac le plus pollue pendant quel- 
ques jours. 

Les prelevements dans chacun des mesocosmes ont ete realises a 



l'aide de tubes de carottages en plexiglass de 5,72 



cm* 



Trois prises 



simultanees ont ete effectuees pour les hydrocarbures et les compta- 
ges de meiofaune avec une frequence hebdomadaire puis mensuelle, pen- 
dant plus de six mois du 17 mars 1981 au 29 septembre 1981. Chaque 
carottage a ete fractionne en trois niveaux : 0-4; 4-8; 8-12 centime- 
tres pour analyse de la repartition verticale des parametres. 

Les hydrocarbures ont ete extraits au tetrachlorure de Carbone 
a partir de 10 grammes de sediment seche a 60°C a l'etuve. Apres pas- 
sage sur Fluorisil, destine a eliminer les fractions oxydees et les 
hydrocarbures endogenes, l'extrait a ete lu au spectrophotometre in- 
frarouge UNICAM SP 1100, a une longueur d'onde comprise entre 2500 et 
3000 cm" , avec calage du pic caracteristique a 2925 cm -1 . Les resul- 
tats ont ete exprimes en ppm (mg/kg sable PS) d' apres l'abacle reali- 
see sur l'Arabian light IFP. 

La filtration sur Fluorisil provoque une retention sur le fil- 
tre de l'ordre de 60.4% du poids du produit d'origine. 



231 



Les organismes de la meiofaune ont ete fixes au formol 4%, colo- 
res au rose bengal et tries apres passage sur tamis de 40 u et elutria- 
tion. Des lots de 100 Nematodes ont ete mesures et identifies pour la 
determination de la biomasse et de la composition specifique. 



RESULTATS 



Evolution des hydrocarbures 

Les quantites d 'hydrocarbures introduites dans les modules fai- 
blement et fortement pollues correspondent a des teneurs initiales 
theoriques de 223 et 2236 ppm puisque seuls les quatre premiers centi- 
metres du sediment (soit 17.7 kg) sont contamines et que le passage de 
l'extrait tetrachlorure sur Fluorisil entraine une perte de 60.4% au 
dosage. 

En effet, 1 'analyse de la repartition verticale des hydrocarbu- 
res dans la colonne sedimentaire en utilisant ce type de dispositif 
experimental revele une penetration quasiment nulle du polluant sous 
la surface. Seule la tranche 0-4 centimetres contient des hydrocarbu- 
res en quantite notable et une penetration limitee dans la tranche 
4-8 centimetres n'apparalt episodiquement qu'a partir du 106eme jour. 
Le temoin n'a jamais montre la moindre trace d' hydrocarbures. 

La figure n° 2 fournit 1' evolution des teneurs au cours du temps 
dans les bacs faiblement et moyennement pollues. 

L' evolution des teneurs dans le module faiblement pollue indique 
une degradation extremement faible au cours des six mois d'experience 
avec une heterogeneite des teneurs mesurees tres legerement plus accen- 
tuee en debut d'experience. 

Par contre, 1' evolution des teneurs dans le module fortement 
pollue met en evidence une tres forte heterogeneite des concentrations 
jusqu'au 23eme jour de prelevement qui reflete la repartition en aggre- 
gats des hydrocarbures a la surface du substrat ainsi qu'il a ete pos- 
sible de l'observer en plongee in situ sur les sables d'origine de la 
Pierre Noire. Cette heterogeneite tend a se reduire ensuite considera- 
blement du fait de la bioturbation. Le pic d'abondance des hydrocarbu- 
res observe au 23eme jour reste compatible avec les incertitudes de 
l'intervalle de confiance a la moyenne. II est lie* probablement aussi 
au delai necessaire au coulage de toutes les particules mazoutees ayant 
partiellement tendance a flotter a la surface de l'eau du compartiment 
principal en debut d'experience. 

La disparition des hydrocarbures entre 23 et 93 jours semble sa- 
tisfaisante puisqu'elle indique une evolution de 2979 ± 1672 ppm a 248 
± 52 ppm soit 38.5 mg HC/kg sable/jour (24 mg HC/kg sable/jour si l'on 
tient compte d'une valeur initiale theorique de 2236 ppm. II est cepen- 
dant impossible de considerer cette valeur comme un taux de degrada- 
tion realiste du fait de 1 'heterogeneite des teneurs initiales mesurees 
mais aussi d'une remontee incomprehensible des teneurs en hydrocarbu- 
res au 106eme et 124eme jour. 

232 



3000 



1500 



1000 - 




ISO Day* 



FIGURE 2. Evolution des teneurs en hydrocarbures et de leur ecart a 

la moyenne, dosees par la methode infra-rouge apres passage 
sur Fluorisil, dans le sable des modules fortement pollues 

(100 g HC : • •) et faiblement pollues (10 g HC : 

o -"-'o). Les hydrocarbures sont presque toujours concentres 
dans les quatre premiers centimetres du sediment. 

La difficulte d' interpretation des resultats des dosages effec- 
tues par infrarouge apres passage de l'extrait au CCli, sur Fluorisil 
montre done 1' extreme heterogeneite de la repartition des hydrocarbu- 
res dans le sediment, meme a l'echelle de quelques dizaines de centi- 
metres. II apparait difficile de realiser des calculs de biodegrada- 
tion dans des microcosmes ou l'on ne preleve qu'un faible aliquot du 
volume de sable contamine. 



Evolution des densites de la Meiofaune 



Les densites initiales du Meiobenthos dans le mesocosme temoin 
et dans ceux contamines par les hydrocarbures etaient comparables (non 
signif icativement differentes au niveau 5% par le test de Kruskall Wal- 
lis) . Les valeurs initiales trouvees de 1218 ± 13 Nematodes/10 cm 2 et 
de 198 ± 26 Copepodes harpacticoides/10 cm 2 , deux groupes qui consti- 
tuent la quasi totalite des organismes meiobenthiques recenses, peuvent 
etre favorablement comparees avec la densite relevee dans le milieu na- 
turel a la meme date (1357 Nematodes et 105 Copepodes/10 cm 2 ) dans les 
douze premiers centimetres du sediment en mars 1981. 

Bien que 1' analyse de la repartition verticale montre qu 1 environ 
70% des nematodes et 44% des copepodes sont concentres dans les quatre 
premiers centimetres du sediment, les imperatifs de temps de tri ont 
conduit a estimer les densites seulement dans les quatre premiers cen- 
timetres. _.. 




180 Days 



FIGURE 3. Evolution des densites (et de leur ecart a la moyenne) des 
Nematodes dans les quatre premiers centimetres du sediment 
pendant une periode de six mois. Temoin : -- 0; Module 
faiblement pollue : o -.- o; Module fortement pollue : 

• • • 



Quel que soit le module considere, les densites de nematodes ont 
tendance a decroitre en circuit clos (Fig. 3). Cependant, il est pos- 
sible de distinguer : - une periode initiale de deux mois environ ou 
les valeurs trouvees dans les bacs pollues sont generalement plus for- 
tes que dans le temoin; 

- une periode ulterieure ou les densites dans 
ces modules contamines ont tendance a etre legerement plus faibles par 
rapport au temoin. 

II apparait done que la phase de pollution primaire serait ca- 
racterisee par une proliferation des nematodes (1,5 a 2 fois le niveau 
du temoin) mais que rapidement apparaitrait un declin lent (0,5 a 0,8 
fois la valeur du temoin dans le bac le plus pollue, 0,7 fois a une 
valeur comparable au temoin dans le bac faiblement pollue). Ces obser- 
vations sont compatibles avec celles relevees dans le milieu naturel 
(Elmgren 1980 a; Boucher et al. 1981). 



234 



L'evolution des Copepodes harpacticoides (Fig. 4) montre au 
contraire un effet depressif des hydrocarbures sur le niveau de den- 
site du peuplement. Les abondances observees dans le temoin restent 
toujours superieures a celles des bacs polities malgre des fluctua- 
tions importantes des densites au cours de 1 'experience. Dans le bac 
le plus pollue, les densites de Copepodes deviennent faibles apres le 
21eme jour. 




20 40 00 



00 100 120 140 100 IIODayi 



FIGURE 4. Evolution des densites (et de leur ecart a la moyenne) des 
Copepodes harpacticoides dans les quatre premiers centime- 
tres du sediment pendant une periode de six mois. Temoin : 

0; Module faiblement pollue : o -.- o; Module forte- 

ment pollue : • •• 

Evolution du rapport Nematodes/Copepodes 

L'utilisation de ce rapport dans les etudes de pollution vient 
recemment d'etre proposee par Raffaelli et al (1981). Cette proposi- 
tion seduisante derive de deux considerations : 

- d'une part les Copepodes sont apparemment plus sensibles que 
les Nematodes au stress des pollutions; 

- d'autre part l'utilisation de la meiofaune dans les etudes 

d 1 impact ne se justifie que si celle-ci repond avant que les effets ne 
deviennent visibles sur la macrofaune. L'un des obstacles majeurs a 
1' interpretation de cet indice reside dans le fait que celui-ci est 
correle negativement avec la mediane granulometrique du sediment. L' ex- 
perimentation permet d'eliminer ce facteur qui obscurcit 1' interpreta- 
tion des resultats. 



235 



N/C 




20 40 60 



80 100 120 140 160 180 Days 



FIGURE 5. Evolution du rapport Nematodes /Copepodes dans les quatre 

premiers centimetres du sediment pendant les six mois d' ex- 
perience. Temoin : 0; Module faiblement pollue : o o; 

Module fortement pollue : • •. 



La figure 5 montre l'evolution de ce rapport dans les trois mo- 
dules experimentaux. Les valeurs sont d'autant plus fortes que le bac 
est plus pollue par les hydrocarbures . Ainsi le temoin presente tou- 
jours des valeurs faibles comprises entre 1.07 et 12.40 (moyenne : 
5.04 ±0.50 par 33 mesures en six mois). 

Le bac faiblement pollue presente des valeurs legerement plus 
fortes et plus variables comprises entre 1.64 et 20.07 (moyenne : 7.81 
± 0.78 par 32 mesures). Enfin le module fortement pollue presente des 
valeurs nettement plus elevees mais fluctuantes. Deux periodes corres- 
pondant a des fortes valeurs peuvent etre distinguees entre 22 et 50 
jours (N/C = 37 a 51) et entre 124 et 188 jours (N/C = 16 a 71) sepa- 
rees par une periode de faible valeur a 71 jours (N/C = 5 a 14). 



236 



La sensibilite de cet indice semble done se confirmer puisqu'un 
accroissement sensible est discernable apres 25 jours d'experience 
dans le bac fortement pollue du fait de la quasi disparition des Cope- 
podes, alliee a une proliferation des Nematodes. La generalisation de 
son utilisation demande cependant de preciser les modalites de ces 
fluctuations dans differentes conditions experimentales en tenant 
compte des changements de la composition specifique aussi bien des 
Nematodes que des Copepodes et de leur niveau de competition pour la 
nourriture par exemple (Warwick 1981). II est probable que le retour 
de ce rapport a des valeurs faibles dans le bac le plus pollue corres- 
pond a un changement de la composition faunistique des Copepodes. 



Evolution des parametres Abondance, Biomasse et Diversite. 

La plupart des etudes utilisant les modifications de la macro- 
faune pour mettre en evidence 1' impact des pollutions preconisent 
l'emploi de parametres simples tels le nombre d'especes, 1' abondance 
et la biomasse (Pearson et al. 1978; Glemarec et al.1981 entre autres) 
Cette approche pose pour 1' instant de serieux problemes methodologi- 
ques en ce qui concerne la Meiofaune. Les progres realises dans la 
systematique des groupes dominants des Nematodes et des Copepodes 
permettent d'envisager raisonnablement la determination de routine 
du nombre d'especes dans un echantillon representatif de la popula- 
tion (100 a 300 individus) malgre la grande diversite de ces groupes. 
II n'en est pas de meme en ce qui concerne 1' evolution de la biomasse 
du meiobenthos dans un echantillon donne. En effet, les methodes ac- 
tuellement utilisees posent generalement l'hypothese que la biomasse 
moyenne ne varie pas au cours du temps, ce qui n'est bien sur pas le 
cas. Elles consistent par consequent soit a evaluer les biovolumes a 
la chambre claire d'un microscope en utilisant des formules d'equiva- 
lence (Andrassy 1956; Wieser 1960; Juario 1975), soit a peser a la 
microbalance de precision un unique lot de quelques centaines a quel- 
ques milliers d' individus (De Bovee 1981; Guille et al. 1968). 

Les resultats presentes dans cet article doivent etre conside- 
red comme la mise au point d'une methode d' evaluation des indices vo- 
lumiques sur la meiofaune qui permet d'analyser rapidement chaque pre- 
levement et evite les incertitudes des methodes de pesee. Chacun des 
lots de 100 specimens montes entre lame et lamelle pour la determina- 
tion a ete grossi cent fois grace a un projecteur de profil. Les con- 
tours de chaque individu identifie ont ete traces puis analyses a la 
table digitalisante d'un analyseur d' images. Le volume a ete calcule 
et exprime en poids sec en utilisant une valeur de densite de 1,13 
(Wieser 1960) et un rapport Poids sec/Poids frais = 0,25. 

Les autres parametres classiquement utilises tels que nombre 
d'especes (S) , Indice de diversite de Fisher et al. (a), Indice de 
diversite de Shannon (H) et Equitabilite de Pielou (J) ont ete aussi 
calcules au temps zero, 36 jours (avant la chute de densite) et 93 
jours (apres la chute de densite) de l'experience dans chacun des 
trois modules sur des echantillons de 100 individus (Tableau I). 

Dans le bac temoin, 1 'evolution du poids sec individuel n'in- 

dique pas de fluctuations signif icatives puisque les limites des in- 

tervalles de confiance de la moyenne se recoupent (0.088 a 0.207 ug 

PS/individu) . 

237 



36 93 

653 485 
0.150 ± 0.057 (97) 0.101 ± 0.012 (101) 
98.1 49.1 

33 33 
17.19 17.19 

4.62 4.46 
0.92 0.88 

831 365 
0.071 ± 0.0009 (90) 0.103 ± 0.035 (101) 
59.1 37.7 

34 34 
18.15 18.15 

4.35 4.15 
0.86 0.82 

955 418 
0.125 ± 0.029 (95) 0.019 ± 0.003 (90) 
119.6 7.8 
28 17 
12.91 5.88 
4.05 2.19 
0.84 0.54 


TO 

633 
0.125 ± 0.015 (97) 
79.3 
29 

13.71 
3.97 
0.82 

1007 
0.130 ± 0.028 (100) 
131.2 
29 

13.71 
4.46 
0.92 

1016 
0.107 ± 0.015 (101) 
108.9 
23 
9.35 
3.71 
0.82 


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238 



La biomasse est sensiblement plus forte au temps zero et sur- 
tout a 36 jours qu'a 93 jours essentiellement du fait de densites plus 
fortes. Le nombre d'especes identifiers est assez constant (29 a 33) 
ainsi que les divers indices de diversite. 

Dans le bac faiblement pollue, le poids sec individuel apres 93 
jours n'est pas signif icativement different de celui de l'etat initial. 
La decroissance de la biomasse 131,2 a 37,7 ug PS) est surtout liee a 
la chute des densites (1007 a 365). Le nombre d'especes recense a ten- 
dance a legerement augmenter (29 a 34) ce qui provoque une augmenta- 
tion parallele de l'indice de Fisher et al. (13,71 a 18,15). La dimi- 
nution lente de l'indice de Shannon et de 1 'equitabilite indique l'ap- 
parition d'une hierarchisation plus marquee au cours du temps. 

Dans le bac fortement pollue, 1 'evolution des densites est si- 
milaire a celle du module faiblement pollue. Apres 36 jours, les va- 
leurs des parametres demeurent comparables a celles de l'etat initial. 
Apres 93 jours, par contre, le poids sec moyen chute fortement (0.019 
± 0.003 ug PS) d'ou une reduction brutale de la biomasse (7.8 ug/10 cm 2 ) 
Celle-ci est liee au remplacement du peuplement d'origine par quel- 
ques especes de petite taille caracteristiques des milieux riches en 
matiere organique (Leptclaimus tripavillatus Boucher 1977, Monkystera 
aff. disjuncta Bastian i 865 ; Monhystera pusilla Boucher 1977) et mises 
en evidence dans des experiences prealables d'eutrophisation (Boucher 
1979). 



DISCUSSION 



Ces simulations de pollutions en microecosysten-es sediment ai- 
res soulignent la difficulte d' interpreter les phenomenes de degrada- 
tion des hydrocarbures dans les sediments. La disparition de ceux-ci 
n'est pas detectable pendant la duree de l'experience dans le module 
faiblement pollue; elle est anarchique dans le bac fortement containi- 
ng. II ne semble done pas possible de caracteriser aisement une pol- 
lution par le niveau du polluant dans le milieu avec la methode em- 
ployee. 

L'utilisation d'organismes sensibles au polluant (indicateurs 
biologiques) integrant 1' ensemble des consequences du stress parait 
plus fiable pour caracteriser un impact. Elle suppose, pour etre ef- 
ficace, que ceux-ci repondent avant que la perturbation devienne evi- 
dente. Si certains organismes de la macrofaune benthique repondent de 
facon nette au stress primaire de la pollution par hydrocarbures (Dau- 
vin 1979 a et b et 1981) la duree des cycles (1 a 10 ans) rend proble- 
matique l'analyse des effets differes (Chasse et al. 1981). 

Du fait de la rapidite de reproduction, la meiofaune, dont les 
Nematodes et les Copepodes constituent l'essentiel des organismes, est 
un materiel prometteur pour comprendre les mecanismes regissant la 
destructuration et la restructuration d'un ecosysteme. 

Ces experiences de contamination brutale par hydrocarbures ne 
suggerent pas un effet tres important sur le niveau des densites des 
Nematodes. Leur augmentation entre 21 et 50 jours ne semble pas liee 

239 



a un developpement d'opportunistes necrophages comme le suggere Chasse 
(1978) puisque la composition faunistique reste tres comparable a celle 
du temoin. La chute des densites observee ulterieurement dans le bac 
le plus pollue est conforme aux resultats obtenus experimentalement 
in situ par Bakke et al. (1980) ou en mesocosmes par Elmgren et al. 
(1980 b). Elle s'accompagne d'un changement tres perceptible de la com- 
position faunistique avec reduction du nombre d'especes et diminution 
de la biomasse. 

Contrairement a 1 ' idee generalement admise, le groupe des Nema- 
todes peut done constituer un indicateur biologique fiable des modifi- 
cations de l'ecosysteme (Piatt & Warwick, 1980) puisque leurs possibili- 
tes adaptatives permettent a certaines especes de se maintenir quelles 
que soient les conditions de milieu, a d'autres de proliferer en quel- 
ques semaines pour occuper la niche laissee vide. La determination ex- 
perimental de groupes de Nematodes a comportement similaire vis-a-vis 
de 1 'eutrophisation ou des pollutions, apparait done comme une voie de 
recherche prometteuse pour caracteriser 1'etat ou la dynamique des eco- 
systemes perturbes. 



SUMMARY 

Experimental study of hydrocarbon pollution in a sand microecosystem 
I. Effect of the sediment contamination on meiofauna. 

The effects of hydrocarbon pollution, at two different intensi- 
ties with respect to a control, on the microecosystems were studied 
using recirculating experimental tanks containing 100 liters of subti- 
dal fine sand. Changes in the population characteristics of meiofauna 
(nematodes and copepods) were chosen to follow the effects of oil pol- 
lution. Irrespective of the intensity of pollution, the density of ne- 
matodes in the experimental tanks increased at a significantly higher 
rate than in the control tank during the first two months after pollu- 
tion and then decreased slowly. The density of harpacticoid copepods 
was negatively related to the intensity of oil pollution. It appears 
that the nematodes /copepods ratio would be an useful indicator of the 
degree of oil pollution. 

After 3 months of experimental duration, the faunal composition 
of the nematodes in the highly polluted tank was drastically modified. 
This change is evident from a sharp fall in biomass and species diver- 
sity; small opportunistic nematode species, known for their associa- 
tion with eutrophicated environment, became dominant. Changes in the 
meiofauna population parameters in the slightly polluted experimental 
tank did not show any significant variation from those in the control 
tank. 



REMERCIEMENTS 



L'ensemble des tris de la meiofaune a ete realise par Melle L. 
Cras, technicienne CNRS que nous tenons plus particulierement a remer- 
cier avec toutes les personnes ayant collabore a ce travail. 

240 



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243 



EVOLUTION A MOYEN-TERME DU MEIOBENTHOS 

ET DU MICROPHYTOBENTHOS SUR QUELQUES PLAGES TOUCHEES 

PAR LA MAREE NOIRE DE L 'AMOCO- CADIZ 

par 

Philippe BODIN et Denise BOUCHER 

Universite de Bretagne Occidentale , Laboratoire d'Oceanographie 
biologique, 6 avenue Le Gorgeu, 29283 Brest Cedex, France. 



ABSTRACT 

The ecological follow-up undertaken after the Amoco-Cadiz oil 
spill, on the beaches Brouennou and Corn ar Gazel (mouth of Aber 
Benoit) and Kersaint (near Portsall), was continued untill november 
1980. Chlorophyll pigments have suffered little quantitatively from 
the direct effect of pollution, but the study of temporal variations 
in the meiofaunal densities revealed disturbances in seasonal cycles. 
Other factors, e.g. hydrodynamic fluctuations and macrofaunal preda- 
tors, could act as regulating mechanisms on the evolution of the po- 
pulations . 

The effects of pollution are particularly obvious in some fau- 
nistic imbalances, as the study of harpacticoid copepods showed. 
However, particular evolutionary trends between and within ecologi- 
cal groups of species implied that recovery was nearly complete, at 
least on exposed beaches . 

The conclusions drawn to date are tentative because of the lack 
of reference data, and it is intended to continue the survey annual- 
ly in spring. 

Key words : Pollution , Amoco-Cadiz, Chlorophyll pigments, Meiofauna, 
harpacticoids , Beaches. 

RESUME 

Le suivi ecologique mensuel entrepris , a la suite de la catas- 
trophe de 1 'Amoco-Cadiz. sur les plages de Brouennou et Corn ar Gazel, 
a 1' entree de l'Aber Benoit, et de Kersaint pres de Portsall, a ete 
maintenu jusqu'en novembre 1980. Alors que les pigments chlorophyl- 
liens ne semblent pas avoir souffert de l'action directe de la pol- 
lution, 1' etude des variations temporelles de la densite de la meio- 
faune revele une perturbation des cycles saisonniers . D'autres fac- 
teurs , tels que l'hydrodynamisme et les predateurs de la macrofaune , 
peuvent intervenir en tant que mecanismes regulateurs . 

Les effets de la pollution sont surtout sensibles au niveau de 
certains desequilibres faunistiques , comrae le montre 1 'etude des Co- 
pepodes Harpacticoides . Cependant , une certaine evolution des groupes 
ecologiques permet de penser qu'un processus de retour a l'etat ini- 
tial est en cours d 'achievement , du moins sur les plages de mode battu. 

En fait, 1' absence d'etats de references nous oblige encore a la 
prudence dans 1 'interpretation des resultats , et il est envisage une 
poursuite des recherches sous forme de "veille" ecologiques. 

Mots-cles : Pollution, Amoco-Cadiz, Pigments chlorophylliens, Meio- 
f aune , Harpacticoides, Plages. 

245 



INTRODUCTION 

Dans le cadre du suivi ecologique entrepris , a la suite du nau- 
frage de 1"'AM0C0-CADIZ" , par les Laboratoires de l'Institut d'Etudes 
Marines de l'Universite de Bretagne Occidentale , la meiofaune sensu 
lato et le microphytobenthos de la zone intertidale ont ete l'objet 
d'une etude realisee par le Laboratoire d'Oceanographie biologique . 

Apres une recherche de site effectuee sur la cote nord-Finistere 
au cours des mois de septembre et octobre 1978, deux plages a la sor- 
tie de l'Aber Benoit (Fig. 1), Corn ar Gazel au SW et Brouennou au 
NE, ont ete retenues pour cette etude. Ces deux plages, situees dans 
une zone particulierement eprouvee par la pollution due aux hydrocar- 
bures de 1' "AMOCO-CADIZ" , sont egalement etudiees au point de vue 
physico-chimique et au point de vue de la macrofaune (Le Moal , 1981) 
dans le cadre de ce suivi. II a malheureusement ete impossible de 
trouver dans cette region une plage ecologiquement homologue mais 
non polluee af in de servir de temoin . Une etude parallele , mais por- 
tant uniquement sur la meiofaune sensu stricto , a ete realisee sur 
la plage de Kersaint (pres de Portsall). 










4*40- 



4*M- 



FIGURE 1. Localisation des stations. 



Sur chacune des plages, une station (Quadrat) situee en dessous 
de la mi-maree, dans l'etage mediolittoral , est l'objet de preleve- 
ments mensuels depuis mars 1978 pour la plage de Kersaint, novembre 
1978 pour les plages de Brouennou et Corn ar Gazel. Sur cette der- 
niere , deux prelevements "de reference" ont pu etre realises le 17 
mars 1978, avant l'arrivee de la nappe d'hydrocarbures . 

Une premiere publication (Bodin et Boucher, 1981) faisait etat 
des resultats acquis en juillet 1979. La presente note les complete 
par les donnees obtenues jusqu'en novembre 1980 et tente une re- 
flexion sur l'ensemble de ce suivi ecologique. 

246 



Les techniques de prelevement et de traitement des echantillons , 
ainsi que les principaux parametres edaphiques , ont deja ete exposes 
dans la premiere publication, nous ne les reprenons done pas ici . 
Nous rappelons simplement quelques caracteristiques granulometriques 
essentielles sous forme de courbes ponderales cumulatives (Fig. 2). 
De plus , nous presentons le prof il topographique de deux des plages 
prospectees (Fig. 3) et les variations temporelles de la temperature 
et de la vitesse du vent (Fig. 4). 







i/ 


75- 




1 1 

if 

i 

j KERSAINT 


50- 




/ 3/80 — 
t p I 

1 Md 190 pm 
' So 1,15 


25- 


i 
ji 
/ 

li 
// 


6/80 

p % 
Md 190 pm 
So 1,09 



ij 




it 
ij 
It 

,'/ CORN AR 


GA2EL 


,/ 3/80 - 




i P l 
i/ Md 130 
'/ So 1,2 


pn 


r f 6/80 - 




' p 1 
7 Md 130 
,7 So 1,1£ 


fjm 



6 3 80 100 125 ISO 200 



63 SO 100 12S 160 200 




63 BO 100 12S 160 ?00 



FIGURE 2. Granulometrie : courbes ponderales cumulatives. 

Teneur en pelites (p %), Mediane (Md), Indice de triage (So). 



BROUENNOU 



supralittoral 
Imediolittoral 

PMMEC40) 



TORAL 




supralittoral 
Imediolittoral 

PMME(40) 



CORN AR GAZEL 
~-» Galets 



INFRALITTORAL 
BMME (40) 




FIGURE 3. Profil topographique des plages. Limites des etages bathy- 
metriques. Emplacement des quadrats (Q). 



\ 



\/ 






/ 



\ 



n'd| j'f'm' »'m' j' j' a' s O n O I J f 

1979 



5 O N D p 



/v 






r~' 



\ 



I 



/ 



1980 



ndTj fmamj j a so no 

1979 



SON O w 



1980 



FIGURE 4. Temperature de l'air (a), vitesse du vent (b) : variations 
des moyennes mensuelles . 



Une correction doit cependant etre apportee (Bodin et Boucher, 1981, 
p. 328) : a la place de P.M.M.E. il faut lire B.M.M.E., et a la 
place de B.M.M.E. il faut lire B.M.V.E. 

247 



RESULTATS 
Pigments chlorophylliens 

Un depouillement additionnel de carottes pour les prelevements 
anterieurs a septembre 1979 modifie legerement les chiffres prece- 
demment obtenus et publies (Bodin et Boucher, 1981). 

Le nombre de carottes utilise a permis l'utilisation de tests 
statistiques : test U de Mann-Whitney et test de Kruskall-Wallis ; 
hypothese nulle rejetee au niveau 5 %. 

Brouennou 

Dans les premiers centimetres d'epaisseur du sediment on observe 
une decroissance tres rapide des teneurs en pigments chlorophylliens, 
ce qui nous a permis de limiter 1' etude aux quatre premiers centi- 
metres . 

Pour la chlorophylle a, ce gradient est tres marque (on retrouve 
en moyenne 12 % de la teneur superficielle sous 4 cm d'epaisseur) et 
regulierement observe dans les prelevements (a 1' exception des mois 
de decembre 1978 et 1979). 

L'heterogeneite spatiale est importante et , de ce fait, les te- 
neurs moyennes calculees pour les deux premieres couches (0-0,2 cm 
et 0,2-1 cm) ne sont pas significativement differentes pour la majo- 
rite des prelevements mensuels , alors que la presence du film super- 
ficiel, plus riche en chlorophylle a, est constatee dans 85 % des 
carottes . 

Pour les pheopigments , le gradient est moins accentue (26 % de 
la teneur superficielle sont presents en moyenne sous 4 cm d'epais- 
seur) et moins frequemment observe (absent en novembre et decembre 
1978, de decembre 1979 a fevrier 1980 et de juillet a septembre 1980) 
que dans le cas de la chlorophylle a, ce qui peut etre du en partie 
a ses plus faibles teneurs et done a la moindre precision du dosage. 
L 'enrichissement superficiel en pheophytine n'est rencontre que dans 
63 % des carottes . 

La chlorophylle a est le pigment largement dominant surtout au 
sein des deux premiers centimetres d'epaisseur, la ou se limitent 
les variations temporelles. Sa teneur relative elevee (71 % de la 
somme Ca + Pheo) est un indice de la presence d'une active popula- 
tion de microphytes dans cette zone correspondant a l'epaisseur 
maximale de la couche oxygenee . 

L ' amplitude des variations temporelles est maximale au niveau 
de la couche superficielle et s'attenue rapidement dans l'epaisseur 
du sediment . 

La chlorophylle a presente, les deux annees, un cycle annuel 
de type saisonnier (Fig. 5a). 

Dans la couche superficielle, le minimum de decembre est suivi 
par un fort accroissement pendant les mois d'hiver ; il aboutit a 
un "plateau printanier" entre mars et juillet 1979 (22,1 Mg/g) et 
entre fevrier et juillet 1980 (15,6 yg/g, en excluant le mois de 
juin). Entre juillet et aout , une nette decroissance est observee ; 
elle est suivie par un "plateau automnal" entre aout et novembre 1979 
(14 ug/g). Au cours de ces deux cycles il faut noter le minimum esti- 
va 1 esquisse en juin 1979, tres prononce en juin 1980, phenomene deja 
observe en zone intertidale (Colijn et Dijkema, 1981) mais non expli- 
cite . 

248 



20 



10 _ 



P9'9 



a 0.0 _ 0.2 cm 
a 0.2 _ 10 cm 
• 1.0 _ 1.8 cm 
1 8_26 cm 
■ 2.6 _ 3.4 c m 
o 3.4_4 2 cm 




¥ "CN- V ■ — " ■-■ i"^ ^• D ~" N > /■ 



I 



NDIJ FMAMJ J ASON Dlj F MAMJ J A S 
*+ 1979 ^ 1980 



10 . 



wg/g 







Ul l A ■ A ' A ■ V A ■ A ' A ' A ' n — nr~ ' A| A ' A ' A ■ * A ' A ' A ' A ' A 

ND. JFMAMJJASONDJFMAMJ JAS 



1979 



1980 



FIGURE 5. Variation des moyennes mensuelles de la chlorophylle a (a) 
et de la pheophytine (b) a Brouennou. 



Dans la couche sous-jacente les fluctuations sont similaires . 
Le plateau printanier, situe entre fevrier et aout . correspond a une 
teneur moyenne de 15,8 yg/g en 1979 et de 11 yg/g en 1980 et le pla- 
teau automnal, entre septembre et novembre 1979, a une teneur moyenne 
de 9,4 yg/g. 

Les deux cycles annuels de la pheophytine (Fig. 5b) different 
essentiellement par le minimum estival tres accuse en 1980, les te- 
neurs moyennes des plateaux. atteints de mars a novembre 1979 
(8,8 yg/g) et de fevrier a mai 1980 (8,5 yg/g), etant semblables . 

Les variations temporelles de ces deux pigments sont paral- 
leles , sauf au cours de l'automne ou elles tendent a s'inverser, 
faisant diminuer la teneur relative en chlorophylle a. 

Les fortes diminutions de concentration sont accompagnees d'une 
disparition ou d'une attenuation du gradient dans l'epaisseur du 
sediment. Cette homogeneisation des couches superficielles , tres 

249 



apparente en decembre 1978 et aout 1979, moins prononcee en decembre 
1979 et juin 1980, peut etre attribute a une erosion de la pellicule 
superficielle et a un brassage du sediment sous 1' action des forces 
hydrodynamiques . 

C'est a la suite de ces decroissances que se situent les plus 
forts accroissements relatifs (100 % entre decembre 1978 et Janvier 
1979, 7*4 % entre decembre 1979 et Janvier 1980, 77 % entre juin et 
juillet 1980). Ces accroissements sont du meme ordre de grandeur en 
hiver et en ete, et il semble done que les facteurs climatiques 
(temperature, eclairement) ne soient pas limitant . 

La comparaison des resultats obtenus en 1979 et en 1980 montre 
pour la chlorophylle a, qu'il n'y a pas de differences significatives 
entre les moyennes mensuelles de ces deux annees des mois de Janvier 
a mars, tandis que celles-ci sont toujours plus elevees en 1979 du 
mois d'avril au mois de juillet. 

Corn ar Gazel 

La distribution des pigments au sein des 12 premiers centimetres 
de sediment s'etant revelee tres homogene , nous avons etudie trois 
couches successives de 4 cm d'epaisseur. 

Les teneurs moyennes en chlorophylle a et en pheophytine varient 
peu entre les trois couches (variation environ de 10 %). On reconnait 
cependant , surtout pour la chlorophylle a , deux types de distribu- 
tion : dans le premier type , la teneur est maximale dans la couche 
superficielle puis decroit regulierement , dans le deuxieme type la 
teneur est maximale dans la couche intermediaire (4-8 cm). 

Sur 1' ensemble des prelevements , la teneur moyenne mensuelle en 
chlorophylle a du sediment est la plus faible dans la couche la plus 
profonde . Entre les deux premieres couches, comme a Brouennou, la 
difference observee n'est pas, le plus souvent , significative du fait 
de l'heterogeneite spatiale ; elle est cependant corroboree par la 
frequence, dans le prelevement mensuel, de chacun des deux types de 
distribution verticale . 

La teneur relative en chlorophylle a du sediment ne varie pas 
entre les trois couches . 

Les teneurs moyennes mensuelles en chlorophylle a (Fig. 6a) de 
la couche superficielle (0-4 cm) s 'accroissent de Janvier a novembre 
1979. Apres la brutale diminution de decembre 1979, les moyennes 
mensuelles mesurees en 1980 sont, a 1 'exception du mois d'avril, 
toujours inferieures a celles de l'annee precedente. Dans la couche 
sous-jacente la variation des teneurs moyennes mensuelles presente 
la meme tendance, mais son amplitude est plus faible. 

Pour la pheophytine on remarque une elevation en automne (oc- 
tobre 1979 - septembre 1980) (Fig. 6b) des teneurs moyennes des deux 
premieres couches et , pour 1 'ensemble des deux annees, une augmenta- 
tion des moyennes mensuelles au cours de l'annee 1980. 

S'il n'y a pas de cycle de type saisonnier apparent au niveau 
des variations des teneurs moyennes mensuelles au sein de chacune 
des couches sedimentaires etudiees, un tel cycle se presente (plus 
nettement pour la chlorophylle a) sous la forme d'une succession 
reguliere des deux types de distribution verticale. Un enrichissement 
subsuperficiel est constate pendant 1' hiver (de novembre a avril) 
alors qu'en ete c'est la couche superficielle qui est la plus riche 
en pigments, ce qui peut etre du a la difference saisonniere de sta- 
bility sedimentaire . 2 =;n 



10 _ 



\ 



hP\ 







A** 

\ 

V 



-TTI 1 — I <P ' A A A I A I A I 4 I I I 1 I A I A n 1 ATI rz 1 A I A I TT — i x » T t nx T"I r"»— 

M A i i S i i N D I J FMAMJJ ASONDljFMAMJJ AS 

1979 ^ 1980 _ 



1978 



>< 



5- 



pg/g 



i a 0_4 cm 

» • 4_8 cm 

I ■ 8_12cm 



A s&§ 




a a ' ' i -1 '&4A | x i i— i z i m — i— i — rj — tx 1 — n-x — r* ' — a~] — x— i — i— i — j—) xx i x — rx — n — r— i — » 

M A ii S ii NdIj FMAMJJ ASONdIj FMAMJJ AS 
1978 m 1979 M 1980 



FIGURE 6. Variation des moyennes mensuelles de la chlorophylle a (a) 
et de la pheophytine (b) a Corn ar Gazel. 



Discussion 



La comparaison des deux plages montre que les teneurs pigmen- 
taires dans les couches superficielles , au moment du minimum hiver- 
nal, sont tres peu differentes (10 pg/g environ). Elles peuvent etre 
assimilees a la valeur intrinseque de Hartwig (1978) et resultent 
ici de l'identite des medianes granulometriques . De la meme f agon , 
la faible difference existant au niveau des valeurs moyennes du taux 
de chlorophylle a (81 % et 71 %) et de l'indice de diversite pigmen- 
taire (voisin de 2) dans la couche superf icielle , peut etre reliee a 
l'identite du taux de pelites . 

La difference de nature et d' action des forces hydrodynamiques 
agissant sur la stabilite et 1 'oxygenation du sediment se reflete 
dans la difference observee pour la distribution des pigments dans 
l'epaisseur du sediment (Fig. 7a, b, c), ainsi que l'ont constate 
de nombreux auteurs depuis Steele et Baird (1968). 



251 



Pheo (vg/q ) Ca (pg/g) 

5 5 to 15 



\ 



o 



PheO {uQ,tq) 




Pneo j 



U 



Ca lug/g / 



FIGURE 7. Repartition de la chlorophylle a et de la pheophytine a 
Brouennou (a) et a Corn ar Gazel (b, c) dans l'epaisseur 
du sediment . 



Sur la plage de Corn ar Gazel, la distribution homogene des 
differentes caracteristiques pigmentaires , mise en place par un 
brassage sous 1' action des vagues, peut se maintenir dans un milieu 
interstitiel presentant de bonnes conditions d' oxygenation (Gargas, 
1970 ; Mclntyre et at. , 1970 ; Hunding, 1971) assurees par l'exis- 
tence de houle et de courants de maree. Dans ces milieux instables 
ou les microphytes sont passivement distribues, l'essentiel de la 
flore est generalement constitue par de petites Diatomees liees aux 
grains (Amspoker, 1977). 

Sur la plage de Brouennou la stabilite de la surface sedimen- 
taire permet le developpement dans la zone photique d'un film super- 
ficiel, tandis que, sous les deux premiers centimetres, en milieu 
non oxygene , on observe un enrichissement relatif en pigments de 
degradation, ceci pouvant etre du a la combinaison entre la migra- 
tion des formes mobiles vers la couche superficielle et la mort des 
cellules en milieu fortement reduit (Gargas, 1970). 

La teneur en pigments chlorophylliens du sediment est en moyenne 
deux fois plus elevee a Brouennou qu'a Corn ar Gazel lorsque sont 
considerees les 'pellicules superf icielles ; elle est au contraire 
deux fois plus faible lorsque les dix premiers centimetres sont pris 
en compte. II est done important de preciser l'epaisseur utilisee 
pour 1' evaluation de la biomasse. Pour une comparaison avec la meio- 
f aune , a Brouennou, ce sont les valeurs mesurees dans le premier cen- 
timetre, zone ou se concentrent les meiobenthontes , qui representent 
la quantite de nourriture disponible et traduisent la stabilite de 
cette zone. 

L' etude des variations saisonnieres , dans le cas de sediments 
instables comme a Corn ar Gazel, montre qu'un cycle quantitatif 
n'est pas apparent sur une annee et e'est essentiellement l'insta- 
bilite sedimentaire qui limite la biomasse des microphytes , la pro- 
duction dans la zone photique devant etre essentiellement exportee 
apres erosion et remise en suspension. 

Lorsque la surface sedimentaire est stable, comme cela est le 
cas a Brouennou, il apparait au contraire un cycle quantitatif 
reproductible. Toutes les etudes menees en zone intertidale montrent 
ce type de cycle annuel des que le sediment presente une fraction 



252 



fine importante (signe de sediment stable) (Cadee et Hegeman , 1977 ; 
Admiraal et Peletier, 1980 ; Colijn et Dijkema, 1981). Ce type de 
cycle se rencontre egalement en milieu infralittoral (Boucher, 1975). 
La biomasse pigmentaire est constante au cours des plateaux de prin- 
temps et d'automne, ce qui laisse presumer soit d'une productivity 
plus faible qu'en hiver, soit de l'etablissement d'un seuil regit par 
les conditions moyennes de stabilite sedimentaire d'une part, et 
d'activite de nutrition du maillon secondaire d' autre part. La pre- 
miere hypothese n'est pas confirmee par les differentes etudes menees 
en milieu intertidal. On ne peut l'etayer, en effet , ni par une photo- 
inhibition (Cadee et Hegeman, 1974 ; Colijn et Van Buurt , 1975), ni 
par un effet limitant des concentrations en sels nutritifs (Admiraal, 
1977), ni par une saturation de la zone photique (Admiraal et 
Peletier, 1980), car la constitution de denses colonies de micro- 
phytes n'est pas suggeree par les teneurs observees (lors de la for- 
mation de croutes de microphytes, des teneurs superieures a 100 yg 
sont mesurees ; Plante-Cuny et at., 1981). La deuxieme hypothese est 
en accord avec 1 'observation de la tendance a un accroissement en 
pheophytine au cours de cette periode . 

La comparaison des resultats obtenus au cours de ces deux annees 
successives (Tableau 1) montre , a Brouennou comme a Corn ar Gazel , 
une diminution globale au cours de la deuxieme annee des teneurs en 
chlorophylle a, alors que la teneur en pheopigments reste inchangee 
ou est en augmentation. Cette variation resulte soit d'un effet 
secondaire de la pollution due aux hydrocarbures de 1' "AMOCO-CADIZ" , 
soit de la variation naturelle pluriannuelle (Cadee et Hegeman, 1974). 



TABLEAU 1. Valeurs moyennes au sein de chaque tranche de sediment 

calculees pour les periodes de Janvier a septembre 1979, 1980, et 

pour la duree totale de 1' etude. 

Ca : chlorophylle a (yg/g) - Pheo : pheophytine (yg/g) 

Ca % : Ca x 100 / (Ca + pheo) - DI : indice de diversite pigmentaire 



Epaisseur 

(an) 


BROUENNOU 


JAW. 1979 - SEPT. 1979 


JAW. 1980 - SEPT. 1980 


NOV. 1978 - SEPT. 1980 


Ca 


Pheo 


Ca '. 


DI 


Ca 


Pheo 


Ca % 


DI 


Ca 


Pheo 


Ca % 


DI 


-0,2 
0,2-1 ,0 

1 -1,8 
1,8-2,6 
2,6-3,4 
3,4-4,2 


18,6 
14,1 
8,1 
4,5 
2,6 
1,5 


6,7 
4,9 
2,9 
2,0 
1 ,3 
1 


73 
74 
74 
69 
67 
60 


1,99 
2,26 
2,76 
3,20 
3,62 
3,97 


13,2 
10,1 
7,1 
3,6 
2,6 
2,0 


6 

3,6 

2,8 

3 

2 

1,7 


69 

74 

72 

54,5 

56,5 

54 


2,3 

2,49 

2,72 

3,19 

3,67 

3,97 


14,9 
.11,1 
7,2 
4,1 
2,7 
1 ,9 


6,1 
4,2 
2,8 
2,7 
I ,8 
1 ,6 


71 

72,5 

72 

61 

60 

54 


2,14 
2,44 
2,81 
3,19 
3,64 
3,89 


Epaisseur 
(cm) 


CORN AR GAZEL 


JAW. 1979 - SEPT. 1979 


JAW. 1980 - SEPT. 1980 


NOV. 1978 - SEPT. 1980 


Ca 


Pheo 


Ca % 


DI 


Ca 


Pheo 


Ca % 


DI 


Ca 


Pheo 


Ca % 


DI 


0- 4 
4- 8 
8-12 


12,9 
12,2 
10 


2 

1,5 

1,5 


87 
87 
87 


2,24 
2,30 
2,42 


8,4 
8,2 
7,55 


2,75 

3,0 

2,1 


76 
74 
78 


2,40 
2,51 
2,64 


1 1 

10,7 
9,1 


2,05 

1,9 

1,8 


82 
78 
82 


2,29 

2,41 
2,54 



253 



Les conditions meteorologiques (facteurs climatiques et hydro- 
dynamiques ) ne peuvent etre retenues comme facteurs determinants de 
cette variation, n'ayant pas ete plus particulierement defavorables 
au cours de la deuxieme annee , si ce n'est en automne , alors que 
les deux plages, pourtant d' exposition differente, ont reagi simi- 
lairement et ceci des le mois d'avril. 

La reprise des activites de grazing est un des facteurs biolo- 
giques qui intervient au niveau de 1' evolution saisonniere et qui 
peut expliquer la difference observee entre les deux annee s . II est 
possible en effet de rapporter ces variations de la biomasse pig- 
mentaire a 1' evolution de la macrofaune au sein du processus de 
decontamination (Le Moal , 1981). Ainsi, la reapparition de l'Amphi- 
pode Bathyporeia sur la plage de Corn ar Gazel peut etre pour partie 
responsable de la diminution de la teneur en chlorophylle a, son 
activite de "brouteur" etant reconnue ( Sundback et Persson, 1981). 



Meiofaune : resultats quantitatifs 

La Figure 8 et le Tableau 2 montrent 1' evolution temporelle de 
la densite (nombre d'individus/10 era de surface) des Copepodes Har- 
pacticoides (echelle * 100), des Nematodes et de la meiofaune totale 
(sensu striato) dans les differents prelevements recueillis aux trois 
stations prospectees . Les Tableaux 3 et 4 indiquent 1' evolution tem- 
porelle (en pourcentage de la meiofaune totale) des autres groupes 
du meiobenthos vrai et de la meiofaune temporaire . II est evident 
que cette evolution est differente d'une station a 1' autre. 

Brouennou 

La densite moyenne (8 033 ind./lO cm 2 ) y est extremement elevee 
en comparaison des donnees de la litterature pour la zone interti- 
dale (Hicks, 1977), et la meiofaune est composee essentiellement de 
Nematodes. Les variations saisonnieres sont assez nettes et a peu 
pres conservees d'une annee a 1' autre, avec des minima en fevrier- 
mars et en septembre (1979) ou juillet (1980), et des maxima en 
avril-Tnai et en decembre -Janvier ou octobre (1980). Cependant , la 
densite moyenne des Harpacticoides est nettement plus faible durant 
la seconde periode (1979-80) : 282 ind./lO cm 2 (contre 593 precedem- 
ment ) . Durant cette seconde periode , le rapport Nematodes/Copepodes 
oscille entre 11 (juin 1980) et 172 (Janvier 1980). 

Les autres groupes du meiobenthos vrai representent un pourcen- 
tage relativement modeste de la meiofaune (maximum : 26,7 % en oc- 
tobre 1979). De plus, ce pourcentage est en regression : il ne de- 
passe pas 3,5 % depuis juillet 1980. 

Les Annelides constituent l'essentiel du meiobenthos temporaire, 
ce qui correspond aux donnees de la macrofaune (Le Moal, 1981). 

Corn ar Gazel 

La densite moyenne de la meiofaune (3 013 ind./lO cm 2 ) y est 
beaucoup plus faible qu'a Brouennou. De plus, e'est a cette station 
que la difference avec la periode etudiee precedemment est la plus 
nette du point de vue quantitatif : la densite moyenne passe de 
4 697 a 1 666 ind./lO cm 2 . Cette regression n'est pas le fait des 

254 



Meiofaune totnli 
Nema; 

A. 



13000- 



10000- 



N 



7000- 
5000- 
3000- 



BROUENNOU 



Q 



i \ 

i \ 
i \ 



\a 



i—\\ 



1 1 
li 
a 

a 



A 



i 
i 



Harpacdcoides 
N/10cm' 
1200 



li \\ p. 



I 
\ 

• * 8 . 



m 



a a 



& // 



/ 

*•/"» 
/ / '"». 



U. ! \\ ! ..-Wtf 






TdI 



-i r— ~r--i*- 



FMAMI JASON D[tFMAMI JASON 

A 

/ i COftN • AR - GAZEL 






a 






' •--•-"•1^ 



S N D| I F M A M I )ASOND[IFMAMI I A S N 

KERSAINT 



"I' 



• fV-. i 






-1 1 1" 



MAMI I A S N D I FMAMI.lASONDM F M A M I , I A S N 

'1978 I 1979 I 1980 

ii 'ii ' i i 

PRINTEMPS ETE AUTOMNE HIVER PRINTEMPS ETE AUTOMNE HIVER PRINTEMPS ETE 



-20 



500 



200 



h BOO 

500 

200 




FIGURE 8. Evolution temporelle des densites de la meiofaune aux 
trois stations. 



Copepodes Harpacticoides , mais celui des Nematodes et des autres 
groupes : de 53,8 % en aout 1979, ces derniers ne constituent plus 
que 11,5 % du meiobenthos vrai en aout 1980. 

Les variations saisonnieres sont encore plus ou moins marquees 
durant la seconde periode , avec un minimum classique en fevrier mais 
aussi un maximum en septembre (1979) et deux legers pics en avril 
et aout 1980). Dans ce biotope mieux oxygene , le rapport Nematodes/ 
Copepodes varie dans des limites plus etroites : 2,3 (septembre 1980) 
a 15 (octobre 1980) . 

Parmi la meiofaune temporaire , les Amphipodes constituent un 
groupe particulierement interessant a cette station ou ils avaient 
subi de lourdes pertes des le debut de la marie noire : ils ont ete 
absents durant tout l'hiver 1979-80, mais ont ete regulierement 

255 



TABLEAU 2. Evolution temporelle des densites de la meiofaune aux 
trois stations (N/10 cm?). 







1 9 


7 9 
















1 9 


8 










BROUENNOU 

Nematodes 
Harpacticoides 
Meiofaune totale 

CORN AR GAZEL 

Nematodes 
Harpacticoides 
Meiofaune totale 

KERSAINT 

Nematodes 
Harpacticoides 
Meiofaune totale 




6/8 


21/9 


8/10 


5/11 


20/12 


17/1 


19/2 


18/3 


30/4 


14/5 


12/6 


10/7 


11/8 


11/9 


23/10 


20/11 




3928 

200 

4257 

7/8 


1312 

33 
1574 

20/9 


6163 

224 
9038 

9/10 


5840 

325 

7654 

6/11 


561 1 

149 

6781 

21/12 


9960 

58 

11022 

18/1 


5179 

63 

7102 

18/2 


3444 

68 

4858 

19/3 


9155 

336 

13721 

29/4 


8624 

611 

12104 

13/5 


6995 

630 

10667 

13/6 


5293 

440 

6140 

11/7 


6368 
432 

7141 

12/8 


8261 

160 

8968 

12/9 


7531 

512 

9499 

22/10 


7904 

400 

8859 


11/7 


585 

189 

1870 

7/8 


1596 

351 

4166 

20/9 


1184 

272 

2283 

8/10 


845 
209 
1264 

6/11 


917 
200 

1444 

21/12 


776 

83 

1073 

18/1 


213 

32 

305 

18/2 


796 

123 

1 181 

19/3 


1480 

180 

1818 

29/4 


1 124 
260 
1726 

14/5 


867 
332 
1387 

13/6 


1021 
283 
1434 

11/7 


1579 

409 

2313 

12/8 


924 
407 
1527 

12/9 


968 

65 

1198 

22/10 


20/11 


603 

208 

2954 


727 

297 

2309 


427 

181 

1252 


719 

82 

3068 


472 

425 

3101 


348 

112 

2352 


832 

123 

1859 


104 

31 

704 


83 

27 

759 


200 

56 

1259 


336 

39 

3623 


341 

160 

3168 


376 
232 
1903 


599 

48 

1295 


783 

77 

1529 


660 

39 

865 


433 
289 
1256 



TABLEAU 3. Evolution temporelle des autres groupes de la meiofaune 
et des nauplii (%). 



BROUENNOU 

ROTIFERES 

TARDIGRADES 

CASTROTRICHES 

OSTRACODES 

TURBELLARIES 

DIVERS 

TOTAL 
NAUPLII 


19 7 9 


19 8 




6/8 


21/9 


8/10 


5/11 


20; i: 


17/1 


19/2 


18/3 


30/4 


14/5 


12/6 


10/7 


11/8 


11/9 


23/10 


20/11 


> 


+ 
0,8 

♦ 
5,9 


+ 
10,4 


12,1 
+ 

+ 
14,6 


2,9 

+ 

9,2 


7,2 

+ 
+ 
+ 

5,4 


+ 
0,6 

1,5 
5,3 


0.5 
0,7 

+ 

1.5 
20,0 


+ 
1, 3 

+ 

1,8 
15,1 


0,9 
3,5 

* 

+ 
2,9 
16,2 


3,4 
3, 1 

♦ 

1,8 
7,9 


0.5 
0,5 

+ 

1.6 
20,5 


+ 
+ 

+ 

1,0 
0,7 


+ 

0,5 

+ 
0,8 
0,7 


♦ 

+ 
0,6 
2,9 


+ 
+ 

* 
♦ 
1,2 


0,6 

♦ 
♦ 

0,5 




6,7 
0,8 


10,4 
0,7 


26,7 
0,9 


12,1 

4,0 


12,6 


7,4 
0.7 


22,7 
2,5 


18,2 
8,5 


23,5 

6,4 


16,2 
5,4 


23,1 
3,3 


1,7 
1.6 


2,0 

0,7 


3,5 

0,8 


1.2 

12,6 


1 ,1 


CORN AR GAZEL 

ROTIFERES 

TARDIGRADES 

CASTROTRICHES 

OSTRACODES 

TURBELLARIES 

DIVERS 

TOTAL 
NAUPLII 




7/8 


20/9 


9/10 


6/11 


21/12 


18/1 


18/2 


19/3 


29/4 


13/5 


13/6 


11/7 


12/8 


12/9 


22/10 




) 


2.3 
1,2 

2,4 
47,9 


0,9 
1,0 
6,9 
2,7 

39,0 


+ 

10,9 
1,2 

21,9 


0,7 

4,8 
0,7 

4." 


2,0 
14,1 

+ 

3,1 


+ 

1 .5 
12,3 

+ 
1,4 
3,3 


6,6 
4,3 
4,3 

3,0 
2,3 


3,1 
12,5 
2.0 
1.3 
2,0 


+ 

+ 
4,1 
1,1 
1,0 
0,7 


1,3 
♦ 
4,9 
1.7 
1.7 
1.0 


+ 

4,5 
0.6 
1.8 
0.6 


3,6 

+ 
1.9 

0.6 


0,8 

9.3 

+ 
1.4 

+ 


0,8 

4,7 

+ 
1.4 

♦ 


+ 

2,6 
0.8 

7,4 

+ 






53,8 
2,9 


50,5 

2,1 


34,0 
0,7 


10,6 
0,6 


19,2 


18,5 


20,5 


20,9 
0,6 


6,9 
1,5 


10,6 
3.2 


7,5 


6.1 


1 1 ,5 


6,9 


10,8 




KERSAINT 

ROTIFERES 
TARDIGRADES 
CASTROTRICHES 
OSTRACODES 

TURBELLARIES 
DIVERS 

TOTAL 
NAUPLII 


11/7 


7/8 


20/9 


8/10 


6/11 


21/12 


18/1 


18/2 


19/3 


29/4 


14/5 


13/6 


11/7 


12/8 


12/9 


22/10 


20/11 


0,9 

14.3 
13.8 

*34,8 


1,1 

5.7 

1.6 

13,8 

31,9 


1,6 

8,1 

♦ 

8,0 

30,3 


1 ,0 
5,6 
7,2 
2,4 

56,0 


2,0 

2.6 

+ 

0,9 

64,5 


4,5 
1.3 
1,0 
1.4 

71,0 


1,3 

7,6 
11,9 

2,6 
20,4 

3,5 


+ 

+ 

2,3 

23.4 

46,2 

5,8 


11,9 
5,4 
2,7 
13,9 
43,7 
3,4 


+ 

2,9 

3,1 

18,7 

18,8 

25,5 


+ 

1,3 

5,9 

4.2 

30,9 

44,6 


2.7 
2,0 
3.2 
18,7 
18,1 
27,7 


+ 
5,1 
3,1 
39,3 
5,4 
2,8 


1.0 
2,3 
16.4 
20,3 
0,9 
3,5 


1,4 
8,9 
4.2 
3.0 
11,5 
8,5 


1.4 
1.8 
6,1 
2,0 
1.4 
2,4 


4,6 
7,4 
5,4 
3,9 
1 .1 
3,2 


71,2 
0,8 


54,1 


48,0 
1,6 


72,2 

1.1 


70.0 


79,2 
0,5 


47,3 


77,7 


81,0 
4,2 


69,0 
9,6 


86.9 
2,1 


72.4 
11.2 


55,7 
10,2 


44,4 
3,8 


37,5 
3.2 


15.1 


25,6 

13,9 



TABLEAU 4. Evolution temporelle de certains groupes du meiobenthos 
temporaire (%). 



BROUENNOU 
Anne I ides 
Gasteropodes 






1 9 


1 9 






19 8 




6/8 


21/9 


8/10 


5/11 


20/12 


17/1 


19/2 


18/3 


30/4 


14/5 


12/6 


10/7 


11/8 


11/9 


23/10 






0,8 


2,8 


1,5 


3,3 


1,8 


0.8 

+ 


0,7 


0,7 


0,7 


2.2 


2,6 


3,1 


1.4 


0,6 

♦ 


+ 




00RN AR GAZEL 




7/8 


20/9 


9/10 


6/11 


2 1 / 1 2 


18/1 


18/2 


19/3 


'•> 1 


13/5 


13/6 


11/7 


12/8 


12/9 


22/10 




Anne 1 ides 

Tanaldaces 

Cumaces 




3,8 

+ 




+ 
+ 


1.3 
3,3 


1,3 


+ 


* 


♦ 




3.8 
2,3 

+ 


3,5 

♦ 
1.4 


♦ 
0,8 


0.5 


+ 

♦ 

3.9 


+ 




KERSAINT 

Anni-lides 
Tanaldaces 
Gai t ,■ t opodei 
Cumaces 


11/7 


r/8 


20/9 


8/10 


6/11 


21/12 


18/1 


18/2 


19/3 


29/4 


14/5 


13/6 


11/7 


12/8 


12/9 


22/10 


20/11 


0,5 


0,9 
1,3 

♦ 


♦ 
2,2 


0,8 
0,9 


0,6 


1.7 
0.8 


1.7 
0,6 


+ 
2,7 


2,0 


+ 
1.0 


: 


1.4 


+ 

1 ,5 
1,8 


1.3 


1,0 
2,9 


3,8 


1 .7 



256 



presents de mai a octobre 1980, confirmant la reinstallation de ce 
groupe tres important au niveau de la macrofaune de Corn ar Gazel 
(Le Moal , 1981). Les Cumaces ont a peu pres le meme comportement 
que les Amphipodes : presque toujours presents entre mai et octobre 
1980, ils atteignent 3,9 % de la population totale en septembre . 

Kersaint 

Suivie mensuellement depuis le 17 mars 1978 , la meiofaune de 
cette station presentait une veritable explosion demographique en 
juin, juillet et aout 1978. Ce phenomene ne s'est pas reproduit par 
la suite, et l'on est revenu a des variations saisonnieres faible- 
ment accentuees, avec un minimum en fevrier-mars (comme aux deux 
autres stations) et un maximum en octobre-novembre 197 9 (comme a 
Brouennou) et en mai-juin 1980. La densite moyenne (2 063 ind./10cm 2 ) 
est la plus faible des trois , ce que laissaient prevoir les carac- 
teristiques du sediment. L'evolution temporelle de la meiofaune de 
cette station a ete marquee par une inversion du rapport Nematodes/ 
Copepodes a partir de mai 1978, date depuis laquelle les Nematodes 
sont devenus preponderants et le sont restes : depuis le mois de 
juillet 1979, ce rapport oscille entre 1,1 (decembre 1979) et 16,9 
(novembre 1980). La densite moyenne des Harpacticoides est d'ailleurs 
passee de 366 ind./lO cm 2 , entre mars 1978 et juin 1979, a 157 entre 
juillet 1979 et novembre 1980, en raison principalement du pic 
"anormal" de juin 1978. 

C'est a Kersaint que les autres groupes du meiobenthos vrai 
sont proportionnellement les plus importants : ils constituent pres 
de 87 % de la population en mai 1980, et les valeurs depassant 70 % 
ne sont pas rares . Les Ostracodes (tous a des stades tres jeunes) 
constituent 39,3 % de la population en juillet 1980, et la propor- 
tion, des Gastrotriches s'eleve a 16,4 % en aout de la meme annee ; 
mais le groupe le plus important et le plus regulierement present 
est celui des Turbellaries . 

Parmi le meiobenthos temporaire , les Tanaidaces sont toujours 
presents (2,7 % au maximum en fevrier 1980), les Annelides de- 
viennent de plus en plus rares a partir de fevrier 1980, alors qu'au 
contraire les Gasteropodes reapparaissent depuis juillet 1980 (3,8 % 
de la meiofaune totale en octobre). 

Discussion 

En 1' absence de donnees anterieures au 17 mars 1978, il est 
bien difficile de dire qu'elle est la periode la plus proche de la 
"normale" du point de vue quantitatif . Les fortes densites observees 
durant la premiere periode a Corn ar Gazel et Kersaint pourraient 
correspondre a une phase d'eutrophisation "anormale" consecutive a 
1' accumulation de matiere organique dans le sediment, accumulation 
resultant elle-meme de la pollution par les hydrocarbures . Dans ces 
biotopes a "haute energie", 1 'hydrodynamisme intense a pu provoquer 
un retour a 1 'oligotrophie durant la seconde periode, alors qu'a 
Brouennou la stabilite du milieu maintenait une certaine eutrophi- 
sation. Malheureusement , nous ne disposons pas de donnees sur la 
teneur en matiere organique des sediments pour etayer cette hypo- 
these . 



257 



On peut aussi expliquer , du moins en partie, les chutes 
de densites de la seconde periode par la reinstallation dans le bio- 
tope de predateurs provisoirement elimines par l'arrivee des hydro- 
carbures ; en tout cas , cette reinstallation est evidente au niveau 
des Amphipodes . 



Evolution comparee de la meiofaune et du microphytobenthos 

La comparaison des resultats obtenus, aux deux stations de 
Brouennou et Corn ar Gazel, pour les pigments chlorophylliens de la 
couche superficielle (0-1 cm) et la meiofaune, montre que 1 'ampli- 
tude des variations et les valeurs maximales de la densite et de la 
teneur pigmentaire sont plus elevees a Brouennou, biotope le plus 
stable. A cette station, des relations de type trophique entre mi- 
crophytes et meiofaune sont fortement suggerees . On observe en effet 
un relais entre la phase d'accroissement des pigments chlorophyl- 
liens (decembre a mars) et celle de la meiofaune (avril-mai), relais 
suivi d'une phase d'equilibre relatif. L'accroissement des pigments 
chlorophylliens apparait done en hiver, alors que l'activite des 
meiobenthontes est ralentie et leur densite en diminution. Les fac- 
teurs climatiques n'etant pas ici limitants pour les microphytes, 
on est en droit de penser que e'est une diminution du "grazing" qui 
favorise leur accroissement . 

A Corn ar Gazel, 1' amplitude des variations saisonnieres des 
pigments chlorophylliens et de la meiofaune, surtout depuis juin 
1979, est fortement limitee par 1' action de l'hydrodynamisme . II est 
possible d'etablir une coincidence entre la distribution verticale 
des pigments et la valeur du rapport Nematodes/Copepodes : ce rap- 
port presente ses plus fortes valeurs en hiver, periode pendant la- 
quelle les Copepodes, assez infeodes ici a la surface (au contraire 
des Nematodes), sont moins nombreux et ou il y a aussi moins de pig- 
ments. L' instabilite de la couche superficielle semble done etre le 
facteur limitant de la biomasse primaire et secondaire a cette sta- 
tion et , de ce fait, une possible relation trophique est masquee . 



Les Copepodes Harpacticoides : etude qualitative 

Comme nous avons deja eu 1' occasion de le montrer (Bodin et 
Boucher, 1981), une etude qualitative est souvent plus revelatrice 
des perturbations d'un peuplement qu'une simple etude quantitative. 

Variations temporelles des differents groupes ecologiques 

Apres determination, les especes d'Harpacticoides ont ete 
regroupees par affinites ecologiques (Tableau 5) d' apres nos ob- 
servations personnelles et les donnees de la litterature , operation 
toujours delicate en raison des incertitudes qui pesent sur l'eco- 
logie de certaines especes. La comparaison de deux annees consecu- 
tives : novembre 1978 a octobre 1979 et novembre 1979 a octobre 1980, 
met en evidence une certaine evolution des groupes ecologiques au 
niveau de chaque station. Pour chacune des deux annees et pour 
chaque groupe , deux variables ont ete calculees : la somme des den- 
sites des especes concernees (E densites) et la dominance generale 
moyenne (D.g.m.) (Bodin, 1977). 

258 



TABLEAU 5. Liste des especes recoltees aux trois stations entre 

aout 1979 et novembre 1980 (s = sabulicole , v = vasicole , 
p = phytophile, e = eurytope , m = mesopsammique) . 







BROUENNOU 




CORN 


AR GAZEL 


KERSAINT 






(6/8/79 


au 20/11/80) 


(7/8/79 


au 22/10/80) 


(11/7/79 au 20/11/80) 


Canuelia &uicigeAa 


Jroupe 
ecol . 


D.g.m. 


Frequence 

% 


V.g.m. 


Frequence 


D.g.m. 


Frequence 
% 


V 


+ 


6 


R 










CanuelZa peAptexa 


s 


12,0 


100 


C 


SO, 3 


1 00 c 


0,4 


35 F 


Hatecti.no ioma heAdman*. 


s 


+ 


12 


R 


+ 


7 R 


+ 


12 R 


Pieudobiadya bedcu.ua 


s 








+ 


7 R 






Kie.no ietetta. sp. 


m 












0,9 


18 R 


TackidiuA di&cipeA 


e 


0,6 


19 


R 


+ 


7 R 


0,8 


29 F 


HictoaAthAidion ie.du.ctum 


V 


+ 


12 


R 










Thompionula kyaenae 


s 








1,1 


20 R 






HaApacticuA falexuA 


s 


13,7 


100 


C 


0,2 


7 R 


6,7 


18 R 


Ti&be sp. 


p 








+ 


13 R 






PoAathateAtAii dovi 


p 


+ 


6 


R 


+ 


7 R 






Vactylopodia sp. 


p 












+ 


6 R 


PaAoi tenheJiia tpinoia butboia 


p 


0,1 


6 


R 






+ 


6 R 


Stenhetia [del. ) patxi&tAXA b-c4p 


v 


0,5 


25 


F 










PobeAXAonia cettica 


p 


24,9 


100 


C 






+ 


6 R 


Sutbamplujaicui urui 


e 


0,1 


37 


F 










AmpliiaA cui valiani 


P 








+ 


7 R 






Amphiaicui longaAticulatixi 


s 








+ 


7 R 






AmplrUa&coZdeA iubdebitii 


P 


+ 


6 


R 










Amphiai colder debitib s. str. 


e 


39,9 


100 


C 










Amptu.ai colder deb-cU* tunccotui 


V 


0,6 


69 


FF 










SckizopeAa sp. 


P 












+ 


6 R 


Apodopiyttui aienicobit, 


m 


+ 


6 


R 






10,9 


100 C 


KtLopiytluA conitAsLCtub s. str. 


m 












5,5 


47 F 


Inteimedopiyttui intelmedua 


m 












+ 


12 R 


PaAateptaataaxi t>pinicau.da 


m 


0,2 


12 


R 


M 


20 R 


55,4 


100 C 


MeiocliAa pygmaea 


e 








+ 


7 R 






Enkydloioma piopinquum 


V 


+ 


19 


R 










RktzothAix. minata 


s 


+ 


6 


R 


2,2 


80 C 


1,9 


71 FF 


Huntemannia jadeniii 


V 


0,3 


37 


F 










Hetelotaophonte itAorru. s. str. 


p 


5,9 


81 


C 


+ 


7 R 






HeXeAotaophonte tUXoiatii 


p 












+ 


6 R 


Panataophonte bieviA06tAU> s.str. 


p 


+ 


6 


R 


+ 


7 R 






PoAonychocamptuA cuAt-tcaudatui 


s 












+ 


6 R 


AiettopiiA kis.pi.da 


s 


+ 


6 


R 










AieZiopi-U, intermedia 


s 


0,4 


44 


F 


15, i 


100 C 


16,9 


88 C 



259 



A Brouennou, quatre groupes ecologiques peuvent etre distin- 
gues : les sabulicoles, les vasicoles, les phytophiles et les eury- 
topes . D'apres les D.g.m., ces groupes se repartissent de la fagon 



suivante : 












Periode du 3/11/78 


Periode du 


5/11/79 




au 8/10/79 


au 23/10/80 




E densites 


D.g.m. 


E densites 


D.g.m. 


Sabulicoles 


942 


18,4 


917 


25,1 


Vasicoles 


477 


9,2 


62 


1,6 


Phytophiles 


1 628 


31,8 


1 043 


28,5 


Eurytopes 


1 525 
3 153 


29,9 
61,7 


1 620 

2 663 


44,4 


Phytophiles + Eurytopes 


72,9 



La premiere annee , les phytophiles dominent , avec pres de 32 % 
des Harpacticoides ; viennent ensuite les eurytopes, puis les sabu- 
licoles et, enfin, les vasicoles. La seconde annee, les eurytopes 
deviennent largement preponderants , avec plus de 44 %, et les phyto- 
philes passent en seconde position. L'ensemble phytophiles + eury- 
topes progresse de plus de 11 % . Les sabulicoles et les vasicoles 
evoluent en sens inverse, c'est-a-dire que les sabulicoles pro- 
gressent de pres de 7 %, alors que les vasicoles sont reduits d'au- 
tant (Fig. 9). 

A Corn ar Gazel, ces quatre memes groupes ecologiques sont 
representes la premiere annee , alors que les vasicoles et les eury- 
topes disparaissent la seconde annee. Mais, a cette station, les 
sabulicoles rassemblent toujours environ 99 % de la population : 







Periode du 


15/11/78 


Periode du 


6/11/79 






au 


9/10/79 


au 22/10/80 






X densites 


D.g.m. 


E densites 


D.g.m. 


Sabulicoles 




3 247 


98,6 


2 305 


99,8 


Vasicoles 




4 


0,1 


- 


- 


Phytophiles 




2 


0,1 


4 


0,1 


Eurytopes 


- Eurytopes 


27 

29 


0,8 
0,9 


- 


- 


Phytophiles h 


4 


0,1 



II n'est done plus question de variations entre les groupes, 
mais il est interessant de noter ici une variation a l'interieur du 
groupe des sabulicoles. Celui-ci est compose essentiellement de deux 
especes : Asellopsis intermedia et Canuella perplexa. La premiere 
annee, A. intermedia est preponderante , avec une D.g.m. de 71,5 % 
contre 18,2 % a C. perplexa. L' annee suivante, e'est C. perplexa qui 
redevient largement dominante ( comme e'etait le cas en mars 1978) avec 
88,7 % de la population, contre seulement 9 % a A. intermedia (Fig. 10) 



A Kersaint , station de sable pratiquement pur, les especes vasi- 
coles sont evidemment absentes . Avec une mediane de pres de 200 ym, 
ce sable est propice a 1 ' installation des formes typiquement inters- 
titielles ; il devient alors necessaire de distinguer, parmi les 
Harpacticoides, un groupe d'especes sabulicoles mesopsammiques et 

260 



N Ul 



o n t ■ ■ • ' 

♦— — ♦ Sabulicotes 



• • Phyloph le 



I \ 
[I => 



rv 



•^ 






i/ji 



\p—\ T->*»~«8 




.- 7 -fc^^-^.-.<-,-. 



N D J 

1978 

FIGURE 

A 
500 



FMAMJJASOND 
1979 



J FMAMJ J ASON 
1980 



9. Brouennou : evolution temporelle de la densite des Harpac- 
ticoides regroupes par affinites ecologiques. 



■ — ■ 
■ — 




' > -' 



M :: S0 N » J F M A M J J A S N OJ F M A MJJA S 

1978 ' 1979 I 1980 

FIGURE 10. Corn ar Gazel : evolution temporelle de la densite des 
principales especes d'Harpacticoides . 



950 
900 

800 

700 , 

600 

500 

400 

300 

200 

10O 
50 



M 
I \ 
i I 
I i 

;' i 
; i 
/ i 



* / 

D 



MfSMpsarnmlquf! 

D D e„. . t n oop.. n 

A A !»»»>"■ • " 



'*■ .'< 



■K 



» J J A S » 

1978 



^T 



■■• :■■*-,•»■:? -,-^5|"B |" , g. 



jr 



f- , -rw - flT. ■ -rj-t-.,- fc v , ; a - , -g- , - n - , ^ , n , — o ,». 



J F M A M J J A S N D I J F M A H J J A S » 
1979 1980 



FIGURE 11. Kersaint : evolution temporelle de la densite des Har- 
pacticoides regroupes par affinites ecologiques. 

261 



un groupe de sabulicoles epi- et endopsammiques . Par ailleurs, comme 
elles sont peu nombreuses et peu abondantes , les especes phytophiles 
et les especes eurytopes sont regroupees dans un seul et meme groupe 



Sabulicoles 
mesopsammiques 

Sabulicoles 
epi-endopsammiques 

Phytophiles + Eurytopes 



Periode du 21/11/78 
au 8/10/79 



£ densites 



1 120 

1 296 
20 



D.g.m. 



45,9 

53,3 
0,8 



Periode du 6/11/79 
au 22/10/80 



Z densites 



1 181 

260 
15 



D.g.m. 



81,2 

17,8 
1,0 



L'evolution de ces groupes est assez significative : durant la 
premiere annee, les formes epi- et endopsammiques dominent avec plus 
de 53 % de la population, alors que, 1 'annee suivante , les formes 
mesopsammiques reprennent largement la predominance avec plus de 
81 % (Fig. 11). 

Diversite 

D'une periode a 1' autre, on observe une chute importante de la 
richesse specifique : 51 especes avaient ete recensees dans les trois 
stations jusqu'en juillet 1979, on n'en compte plus que 36 entre 
aout 1979 et novembre 1980 (Tableau 5). 

De plus, le nombre d'especes dominantes (D.g.m. > 1 %) diminue 
aux trois stations : au total, on passe de 28 especes dominantes du- 
rant la premiere periode a 15 durant la seconde. Parallelement , les 
especes principales voient leur dominance generale moyenne augmen- 
ter. A Brouennou, la D.g.m. de Amphi as coi.de s debilis s. str. passe 
de 23 a 10 i A Corn ar Gazel, la D.g.m. de A. intermedia etait de 
63 % durant la premiere periode etudiee , celle de C. perplexa est 
de 80 % durant la seconde periode. A Kersaint , durant la premiere 
periode, la D.g.m. de A. intermedia etait de 26 %, celle de Kliop- 
syllus aonstriatus s. str. de 25 %, celle de Paraleptastaaus spini- 
oauda de 22 % ; durant la seconde periode, la D.g.m. de P. spiniaau- 
da passe a plus de 55 %. 

Enfin, le cas de K. aonstriatus est interessant a considerer : 
cette espece avait une position tout a fait preponderante jusqu'en 
juin 1978 ; elle est restee frequente par la suite, mais sa D.g.m. 
est tombee de 24,7 a 5,5 %. Cependant , on observe une recrudescence 
de cette forme mesopsammique en novembre 1980, ou sa dominance par- 
tielle est de 48,2 %, ce qui nous rapproche de la situation initiale 
de mars 1978. 



Discussion 

Dans 1' ensemble, on assiste done a une progression des especes 
sabulicoles et a une regression des vasicoles. A Corn ar Gazel et a 
Kersaint, l'evolution aboutit meme a une situation proche de celle 
qui prevalait en mars 1978 ; la diminution de A. intermedia et 
1' augmentation du stock des mesopsammiques laissent supposer une 
depollution du milieu, depollution facilitee par un hydrodynamisme 
plus intense a ces stations. Mais, a Brouennou, la progression des 
eurytopes est encore plus nette que celle des sabulicoles, grace a 
certaines especes telles que A. debilis s. str. qui occupent encore 
largement le biotope. 262 



Doit-on considerer ces especes (A. intermedia et A. debilis 
comme des "opportunistes" au sens ou l'entendent Bellan (1967) et 
Glemarec et Hily (1981) pour la macrofaune ? II est sans doute en- 
core trop tot pour l'af firmer, car nous manquons d'etats de refe- 
rences de ce type en meiofaune. 

Du point de vue de la richesse specif ique , c'est la station de 
Kersaint qui a perdu le plus d' especes (7) par rapport a la premiere 
periode etudiee (en juin 1978, 18 especes etaient presentes a Ker- 
saint ; en juin 1980, il n'y en avait plus que 6) ; Brouennou en a 
perdu 5 et Corn ar Gazel en a gagne 2. Mais le phenomene le plus 
significatif , a notre avis, est la reduction du nombre des especes 
dominantes de chaque station et la tendance a la concentration de 
la faune harpacticoidienne sur quelques especes particulierement 
bien adaptees au biotope. A Corn ar Gazel, cette tendance est poussee 
a l'extreme, c'est-a-dire qu'on a un peuplement presque monospeci- 
f ique , correspondant a un biotope tres selectif d'ou les especes qui 
avaient envahi le milieu a la suite de la pollution disparaissent 
peu a peu. 



CONCLUSION 

Le microphytobenthos est tres vite apparu, sur ces deux plages, 
peu sensible a 1' action directe de la pollution (dosages de pigments 
et observations microscopiques in vivo realises en avril 1978) mais , 
partie integrante de l'ecosysteme , il reagit au desequilibre provo- 
que dans celui-ci. II est un revelateur des caracteres edaphiques du 
biotope et represente un maillon du reseau trophique benthique sous 
sa forme active (chlorophylle a) ou detritique (pheophytine ) . Son 
etude apporte des elements dans la distinction entre des fluctua- 
tions naturelles provoquees par 1 'hydrodynamisme et une reaction a 
la pollution des peuplements animaux interstitiels , ce qui explique- 
rait la difference constatee entre les deux annees . 

Le meiobenthos, en tant que niveau trophique essentiellement 
lie au substrat, est particulierement sensible aux fluctuations des 
parametres ecologiques, comme l'ont montre de nombreux auteurs 
(Gray, 1971 ; Arlt , 1975 ; Giere , 1979, Frithsen et Elmgren , 1979 ; 
Coull et Bell, 1979 ; Renaud-Mornant et Gourbault , 1980 ; Boucher 
et ail . , 1981). Le meiobenthos est particulierement precieux dans le 
cas des biotopes pauvres en macrofaune (Kersaint). 

Du point de vue quantitatif, on peut constater qu'il n'y a pas 
eu d' "hecatombe" dans la meiofaune, comme ce fut le cas en d'autres 
circonstances (Wormald, 1976). Mais on observe des perturbations au 
niveau des cycles saisonniers. A Kersaint, par exemple , il semble 
que la presence d'hydrocarbures ait provoque une regression des peu- 
plements (en particulier des Copepodes Harpacticoides ) jusqu'en mai 
1978, ce qui a eu pour effet de retarder de deux mois le pic de 
printemps . Ce decalage n'est plus que de un mois l'annee suivante 
et il est completement resorbe en 1980. L'elevation temporaire des 
densites observee au bout de quelques mois peut etre une autre con- 
sequence de la pollution liee a une eutrophisation inhabituelle du 
milieu provoqueepar un eventuel apport de matieres organiques . Dans 
les milieux de mode battu, 1 'hydrodynamisme a agit rapidement pour, 
au bout de 12 a 16 mois, operer un retour a l'oligotrophie habi- 
tuelle de ces milieux. D'une certaine maniere , on retrouve ici le 

263 



schema des mecanismes regulateurs des ecosystemes etudies en baie de 
Morlaix par Boucher et at. (1981). Mais, en l'absence d'etats de re- 
ferences anterieurs a la maree noire pour ces stations, nous reste- 
rons prudents dans 1 'interpretation des chutes de densites observees 
a Corn ar Gazel et Kersaint depuis juillet 1979, ou intervient pro- 
bablement aussi la reapparition des predateurs de la macrof aune . 

Beaucoup plus revelatrices sont les perturbations au niveau qua- 
litatif observees chez les Copepodes Harpacticoides . Apres 1' afflux 
d'especes qui a fait suite a la maree noire (juin 1978 a Kersaint), 
une diminution de la richesse specifique jointe a une certaine evo- 
lution des groupes ecologiques montrent qu'un processus de retour a 
l'etat initial est sur le point d'aboutir, en novembre 1980, sur les 
plages de mode battu. Par contre , une plage de mode abrite telle que 
Brouennou semble a un stade de depollution moins avance , a moins que 
ce ne soit la son etat normal... Encore une fois , l'absence de refe- 
rences ne nous permet pas de nous prononcer avec certitude. 

En tout etat de cause, 1' evolution de la meiofaune en milieu 
pollue par les hydrocarbures est done liee essentiellement a 1' oxy- 
genation du sediment et , par consequent, a l'intensite de l'hydrody- 
namisme . 

Une "veille ecologique" devrait permettre de mieux apprecier 
1' impact de cette maree noire, de preciser les delais de retour a 
l'etat d'equilibre initial au sein des biotopes pollues et , d'une 
maniere generale, de mieux comprendre les perturbations des ecosys- 
temes susceptibles d'etre pollues dans le futur. La valeur d'une 
approche par une etude des ecosystemes dans leur ensemble n'est plus 
a demontrer pour 1 'etude des effets des pollutions sur l'environne- 
ment (Linden et al . , 1979). 

II est souhaitable que les etudes entreprises , tant au niveau 
de la macrofaune que de la meiofaune et du microphytobenthos , puis- 
sent etre poursuivies encore plusieurs annees avec, en parallele, un 
suivi des parametres physico-chimiques et sedimentologiques . 



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264 



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265 



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266 



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Ce travail a ete en partie rialisi grace au Contrat NOAA/CNEXO 
n° 79/6184. 



267 



LONG-TERM IMPACT OF THE AMOCO CADIZ CRUDE OIL SPILL ON OYSTERS 
Cvassostvea gigas AND PLAICE Pleuroneotes platessa FROM ABER BENOIT 
AND ABER WRAC'H, BRITTANY, FRANCE 
I. OYSTER HISTOPATHOLOGY 
II. PETROLEUM CONTAMINATION AND BIOCHEMICAL INDICES 
OF STRESS IN OYSTERS AND PLAICE 

by 

1 2 

Jerry M. Neff and William E. Haensly 

1) Battelle New England Marine Research Laboratory, Washington Street, 
Duxbury, MA 02332, USA 

2) Texas A&M University, Department of Vetinary Anatomy, College Station, 
TX 77843, USA 

INTRODUCTION 



On the evening of 16 March 1978, the. Liberian-registered super- 
tanker Amoco Cadiz (233,680 tons deadweight) ran aground and subse- 
quently broke up on Men Goulven rock, Roches de Portsall, approximately 
2 km off Portsall on the Breton coast of France. Over a period of 
several days the complete cargo of the supertanker, which consisted of 
120,000 metric tons of light Iranian crude oil, 100,000 tons of light 
Arabian crude oil and 4,000 tons of bunker fuel was spilled into the 
coastal waters. By mid April the oil had spread to and contaminated in 
varying degrees 375 km of the north and west coasts of Brittany (Hess, 
1978; Spooner, 1978; Southward, 1978). At the time, it was the largest 
oil spill in maritime history. There have been two larger spills since 
then. Two estuaries in the heavily impacted area, l'Aber Benoit 6 km 
east of the spill and l'Aber Wrac'h 9 km east of the spill, face west 
and became heavily contaminated with spilled oil. 

Aber Benoit and Aber Wrac'h are biologically rich and before the 
spill supported large oyster mariculture operations and other commercial 
fisheries. It was therefore of considerable economic and hygenic impor- 
tance to accurately assess the progress of the long-term recovery of the 
estuarine biota from the impact of the oil spill. 

Several factors relating to this spill, including the large volume 
of oil spilled, the prevailing winds and currents which drove much of 
the oil ashore, adverse weather conditions and large tidal prisms which 
resulted in the incorporation of large amounts of oil into bottom sedi- 
ments, and the extreme biological richness of the impacted area, all 



269 



conspired to create a "worst case" scenario for marine oil pollution. 
Therefore, the Amoco Cadiz spill offered a unique opportunity to study 
in detail the long-term impact and timecourse of biological recovery 
from a catastrophic pollution incident. 

While we already know that the immediate biological effects of the 
spill were very serious in some areas (Cross et al. , 1978; Chasse, 1978; 
Chasse and Morvan, 1978), there was very little information upon which 
to base estimates of the rate at which the impacted area would be returned 
to pre-spill biological productivity. We have used several biochemical 
parameters and histopathological examination in an ongoing biological 
survey to assess the health and rate of recovery of marine animals from 
the two heavily polluted estuaries. 

The primary objective of this research program was to assess the 
degree of chronic sublethal pollutant stress experienced by representa- 
tive species of benthic fauna from Aber Benoit and Aber Wrac'h. Two 
indices of stress were used. These are histopathology and biochemical 
composition. We expected the fauna of these severely impacted estuaries 
to exhibit an elevated incidence of various histopathological lesions 
directly or indirectly related to oil pollution stress. As the estuaries 
recovered from the spill the incidence of these lesions was expected to 
diminish. Similarly, the concentrations of certain diagnostic biochemical 
components of the severely stressed fauna were expected to deviate sig- 
nificantly from normal. These diagnostic biochemical indices were 
expected to return to normal as the estuaries recovered and the resident 
fauna became less severely stressed. The results of this investigation 
provide valuable information for assessing the biological recovery of 
these severely polluted estuaries. They also provide a means of diagnos- 
ing, pollutant stress in other polluted environments. 



I. Histopathology of Oysters Crassostrea gigas 

Marine animals readily accumulate petroleum hydrocarbons in their 
tissues from dispersion or solution in sea water and to a lesser extent 
from petroleum-contaminated sediments and food (see recent reviews by 
Neff et al., 1976 a,b; Lee, 1977; Varanasi and Malins, 1977; Neff, 1979; 
Neff and Anderson, 1981). The accumulated hydrocarbons and in particular 
the more toxic aromatic hydrocarbons interact with cellular membranes 
and interfere with membrane-mediated biological processes (Roubal and 
Collier, 1975). Two types of histopathological lesions may result from 
chronic contamination of marine animals with oil. 



270 



The first type is due to the direct toxic effects of petroleum 
hydrocarbons and associated heavy metals on cells. These compounds 
may produce a variety of histopathological lesions in the affected 
organ systems. There are several reports that exposure to sublethal 
concentrations of oil in laboratory or field studies resulted in epi- 
thelial sloughing and discharge of mucus glands in the gills of teleost 
fish (Blanton and Robinson, 1973; Gardner, 1975; Hawkes, 1977; McKeown 
and March, 1978). McCain et al. (1978) reported severe hepatocellular 
lipid vacuolization in English sole Parophrys ventulus following exposure 
for four months to experimentally oiled (Alaskan North Slope crude oil) 
sediments. Rainbow trout fed Prudhoe Bay crude oil-contaminated food 
showed several histopathological changes in the liver (Hawkes, 1977). 
These included glycogen depletion, proliferation of the endoplasmic 
reticulum and focal necrosis with connective tissue infiltration in 
necrotic regions. We have described a wide variety of histopathological 
lesions to embryos and fry of the killifish Fundulus heteroclitus exposed 
chronically during embryonic development to the water-soluble fraction 
of No. 2 fuel oil (Ernst et al. , 1977). In a recent laboratory study 
of the effects of water soluble fractions of crude oil on marine fish, 
one of us (Eurell and Haensly, 1981) observed a variety of histopatho- 
logic changes in liver and gill tissues. 

Little research has been published on the histopathological effects 
of petroleum in benthic marine invertebrates. However lesions similar 
to those described in fish can be expected in the analogous organs of 
marine invertebrates. 

Although crude oil contains known carcinogens such as benzo[a]pyrene 
and 7,12-dimethylbenz[a]anthracene, petroleum- induced cancer has not been 
unequivocally demonstrated in any marine species (Neff, 1979). However, 
there are several reports of increased incidence of cancer-like lesions 
in natural populations of marine invertebrates and fish from hydrocarbon 
polluted sites (See recent symposium volumes edited by Dawe et al. , 1976 
and Kraybill et al. , 1977). 

The second type of histopathological lesion resulting from chronic 
exposure to sublethal concentrations of oil is caused by elevated suscep- 
tibility of contaminated animals to bacterial, virus or parasite infection. 
This increased susceptibility may result from damage to protective epi- 
thelia in the affected animals or to deleterious effects of the pollutant 
hydrocarbons on the immune system of the animal (Hodgins et al. , 1977; 
Sinderman, 1979). Marine animals which have been subjected to chronic 
sublethal oil pollution stress can be expected to exhibit an elevated 
incidence of disease in comparison to non-contaminated animals. 



271 



MATERIALS AND METHODS 



Oysters Crassostrea gigas were collected during five sampling trips 
to France. Dates of these trips were December 1978, April 1979, July- 
August 1979, February 1980, and June-July 1980. In Aber Benoit, oysters 
were obtained from commercial oyster pare owners in St. Pabu and Prat Ar 
Coum. Oysters from Aber Wrac'h were obtained from a commercial opera- 
tion near Paluden. Aber Benoit oysters were not available in August 
1979. Reference oysters were obtained from several places. None were 
completely uncontaminated with oil. On the first two trips, December 
1978 and April 1979, the oyster pare operator at St. Pabu had oysters 
from the Rade de Brest (supposedly uncontaminated) which he was holding 
for later sale. We used these as reference oysters. Subsequent hydro- 
carbon analysis revealed that these oysters were as heavily contaminated 
with petroleum as Aber Benoit oysters. They had probably become contam- 
inated during brief holding in the contaminated water of the Aber, as 
Michel and Grizel (1979) subsequently showed in transplant experiments. 
On the third trip, August 1979, reference oysters were obtained from the 
CNEXO mariculture field station at lie Tudy. On the fourth and fifth 
trips, February 1980 and June 1980, reference oysters were obtained from 
a commercial oyster pare owner on the Rade de Brest at Plougastel. As 
soon as possible after collection, the oysters were shucked and the soft 
tissues fixed whole in freshly prepared Helly's fixative. The visceral 
mass was incised to insure rapid penetration of the fixative. After 
fixation the oysters were washed, dissected into several organs or body 
regions, dehydrated in ethyl alcohol and embedded in paraffin embedding 
medium. Organ systems processed for histopathological examination 
included: visceral mass (includes digestive tract, digestive gland, 
kidney and gonad), gill, and mantle. Sections were cut a 6 ym with a 
rotary microtome and stained with hematoxylin-eosin. All tissue blocks 
and prepared microslides of oyster tissues were labeled, inventoried and 
archived. 

Tissue sections were evaluated qualitatively. The qualitative pro- 
cedures included a description of the average and limits of normal for 
the histological status of each tissue. All histopathological lesions 
were described in full. The incidence of different types of lesions in 
each tissue was recorded. The incidence of different types of lesions 
in each tissue was recorded. These data for the three populations (2 
oil-contaminated stations and one control station) were compared. 
Seasonal and temporal differences in the incidence of pathological 
lesions were also recorded. A photographic record of normal tissue 
histology and of all types of histopathological lesions was made and 
archived. 



272 



RESULTS 



Tissues from 134 specimens of Cvassostvea gigas from four sites were 
examined for histopathologies over five sampling trips. From the speci- 
mens collected, tissue samples of 131 adductor muscles, 127 stomach/ 
intestines, 129 digestive glands, 130 gonads, 134 gills, and 130 mantles 
were examined for a total of 781 tissues out of a possible 804. 

A total of nine types of pathologies were found with an incidence 
of 241 occurrences (Table 1). Five-hundred and ninety of the 781 (75.6%) 
tissues examined were free of pathologies; or, 191 of the 781 (24.3%) 
tissues examined bore one or more pathologies. Of the 241 pathologies 
found, 77 (32.0%) were various types of symbioses, while 164 (68.0%) 
cases apparently were not correlated with symbioses. Table 2 summarizes 
the distribution of pathologies among the tissues examined. Adductor 
muscle had the lowest incidence (3.8%). Digestive gland tissue had the 
highest incidence (23.9%) followed by gill (22.0%), mantle (21.4%), gut 
(17%), and gonad (11.9%). The number of tissues with pathologies was 
nearly evenly distributed among the collecting sites. Oysters from 
reference stations had a higher incidence of lesions, particularly in 
gonad and gill, than oysters from oil-polluted sites. Thirty percent of 
the oyster tissues from both Aber Wrac'h and Aber Benoit bore one or more 
pathologies. Forty percent of the tissues from Rade de Brest and lie 
Tudy combined contained one or more pathologies. 

Overall, mantle bore the lowest number of pathology types (3) while 
digestive gland contained the most types of pathologies (9) followed by 
gut (7), gill (6), gonad (5), and muscle (4). 

Pathologies and their distributions among organs and sites are 
described below. 

1. Muscle . - Muscle tissues were examined from 131 C. gigas. 
Samples for microscopic examination were dissected from the adductor 
muscle and both fast and catch muscles were examined when possible. 
Generally, two tissue samples were taken from each muscle and oriented 
to give both longitudinal and cross sections. 

Histopathologies occurred in 4.6% (6 of 131) of the muscle samples 
examined. There were a total of 9 incidences of. the three pathologies 
described below. Muscle from reference stations contained the widest 
variety of pathologies. No pathologies were found in muscles from Aber 
Benoit. 



273 



Table 1. Types of pathologies, total incidence of each, affected 
organ and collecting site of occurrence 



Pathology Incidence Organ* Site+ 

Amoebae 
Ciliates 

Sporozoans 

Copepods 

Nematodes 

Degeneration 

Necrosis 

General leucocytosis 

Focal leucocytosis 

Total 241 

* Mil - Muscle 
GU - Gut 

DG - Digestive gland 
GO - Gonad 
GI - Gill 
MA - Mantle 

+ C - Control (Rade de Brest and He Tudy) 
W - Aber Wrac' h 
B - Aber Benoit 



3 


DG.MA 


C 


21 


GU.DG.GI 


W,B,C 


29 


MU,GU,DG,G0,GI,MA 


W.B.C 


23 


GU.DG.GI 


B.C 


1 


DG 


W 


10 


MU,GU,DG,G0 


W,C 


9 


GU.DG.GO 


W.B.C 


93 


MU,GU,DG,G0,GI,MA 


W,B,C 


52 


MU,GU,DG,G0,GI,MA 


W,B,C 



274 



Table I. Distribution of patholocies in tissues of oysters 

Crassostrea gigas from two oil contaminated estuaries 
and from reference stations, with sampling times 
combined. 

Organ 
Digestive 
Station Muscle Gut Gland Gonad Gill Mantle Total 

Reference 5 17 20 15 21 18 96 

Aber Benoit 18 19 6 14 17 74 

Aber Wrac'h _§._£]£ 7 18 17 71 

Total 10 41 57 28 53 52 241 



275 



Abnormally high numbers of eosinophilic leucocytes (general 
leucocytosis) were apparent in 1.5% (2 of 131) of the adductor muscle 
samples exmained. Leucocytes were generally spread throughout the 
muscle rather than being in focal aggregations. 

Aggregated eosinophilic leucocytes were present in 1 of 131 adductor 
muscles examined. For the purposes of this report, this aggregation was 
classified as a focal leucocytosis although there was no central core or 
tight concentric arrangement of leucocytes as reported from Crassostrea 
vivg-iniaa (Armstrong et al., 1980). This may be an inflammatory response 
to what appears to be a foreign body, possibly a nematode, at the edge of 
the aggregation. 

Five (3.8%) of the muscles examined contained areas of degenerated 
muscle bundles. This condition was characterized by a breakdown or 
liquefaction of the cellular integrity. Degenerated areas contained 
amorphous, light staining debris and fibers. No pyknotic nuclei were 
present in surrounding whole muscle fibers and no inflammation (increased 
number of leucocytes) was apparent. 

Unidentified sporozoans in the plasmodial stage were found in 1 of 
the 131 muscles examined. 

2. Digestive Gland . - The digestive glands of 129 C. gigas were 
examined. Generally, two samples were taken from each specimen at differ- 
ent levels (anterior and posterior) of the digestive gland. 

Histopathologies were noted in 44.2% (57 of 129) of the digestive 
gland samples examined. There were a total of 64 incidences of the 9 
types of pathologies described below. Twenty-seven of these or 42.2% 
apparently were not attributable to symbioses, while 37 (57.8%) were a 
type of symbiont or were clearly attributable to symbioses (i.e. inflam- 
mation). The distribution of these histopathologies among sampling sites 
is summarized in Table 3. Digestive gland samples from Aber Benoit con- 
tained more pathologies than samples from the other two sites. All 
digestive gland samples from the December, 1978 collection at Aber Benoit 
bore one or more pathologies. Samples from other sites over the five 
collections had no more than 62% incidence of pathologies. 

Abnormally high numbers of eosinophilic leucocytes were dispersed 
throughout the leydig tissue between diverticula in 5 (3.7%) of the 129 
samples examined. In some, leucocytes were also invading the diverti- 
cular epithelium. These cases could have been inflammatory responses 
to parasites such as copepods which were not included in the sectioned 
material. That is, the sections could be at the edge of an inflammatory 
response as described below. 



276 



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277 



Aggregates of eosinophilic leucocytes, were present in 12.4% (16 of 129) 
of the digestive glands examined. Almost all cases were in specimens 
from Aber Wrac'h or Aber Benoit (Table 3). For the purpose of this study, 
these were termed focal leucocytoses. They differed from a general leuco- 
cytosis in that the leucocytes were in a dense clump, sometimes focal, 
rather than being dispersed throughout the tissues. General leucocytosis 
may possibly, in some cases, be a part of a focal inflammation viewed 
some distance from the focal foreign body or parasite. Some cases of 
focal leucocytosis appeared to be confined to the leydig tissue surround- 
ing the diverticulae and were not totally "focal". In most cases, however, 
the condition involved mass invasion of the lumina by leucocytes and/or 
phagocytes with large numbers of leucocytes and/or phagocytes massed in 
the surrounding leydig tissue. Decomposed portions of copepods were 
present in the lumina of two specimens and no doubt were responsible 
for the mass inflammation. Copepods were not apparent in the leucocytic 
inflammations in the digestive glands of the other specimens. These 
inflammations, or focal leucocytoses, may also have been responses to 
copepods as they were identical in all aspects except for the observed 
presence of copepods in the section. 

In one case, well-formed focal aggregates were present in the leydig 
tissue adjacent to the digestive gland. In one, the leucocytes were con- 
fined to a well-formed "pocket", while in another the leucocytes were 
also spread from the "pocket" to adjacent leydig tissue. A massive 
pocket of leucocytes was present in one of the digestive glands examined. 
Leucocytes were confined to the large "pocket". Adjacent leydig cells 
were compressed. 

A degeneration of two or three diverticula was observed in one 
digestive gland and was associated with a copepod parasite. This 
involved a breakdown of the diverticular epithelia and basal membranes 
with leucocytic inflammation. 

Five (3.9%) of the samples examined bore small necrotic areas on 
one to four diverticula. These areas were characterized by a breakdown 
of cellular integrity accompanied by light staining cellular debris and 
a limited number of leucocytes. Necrosis appeared to be minor. 

Amoebae were present in the digestive gland of one C. gigas. 

Digestive glands of 16 (12.4%) of the C. gigas examined contained 
ciliates. Ciliates were evenly distributed among Aber Wrac'h, Aber 
Benoit and Rade de Brest oysters and were sometimes quite numerous in 
the diverticular lumina. Ciliates were oblong, with a somewhat pointed 



278 



antenai, and longitudinal spiral rows of short, stout cilia. They 
did not appear to damage the diverticula. 

Sporozoa were present in the diverticular epithelium of 16 (12.4%) 
of the specimens examined. All but two of the cases were from Aber 
Benoit or Rade de Brest and lie Tudy (Table 3). Sporozoans were spher- 
ical and stained very intensely. They were often surrounded by a clear 
(lysed ?) zone. 

The digestive gland of one specimen bore a nematode which elicited 
an inflammatory response, an aggregation of eosinophilic leucocytes. 

Remains of copepods were noted in the diverticula of 3 C. gigas 
from Aber Benoit. They were accompanied by heavy leucocytic inflammation 
and were being phagocytized as evidenced by the presence of leucocytes in 
the copepods. 

3. Gut . - Samples consisting of stomach, intestine and often esoph- 
ageal and rectal tissues were examined from 127 C. gigas. Generally, 
two tissue samples were taken from each specimen (anterior and posterior 
portions of the visceral mass). 

Histopathologies were noted in 32.2% (41 of 127) of the gut samples 
examined. There were 62 cases of the 6 pathology types discussed below. 
Thirty-five percent (22) involved a symbiont while 40 cases (65%) 
apparently were not symbiotic in nature, although there may be some 
question about this. Specimens from the combined reference stations bore 
more than two and a half times the pathologies as Aber Wrac'h specimens. 
Oysters from Aber Benoit contained slightly fewer pathologies than those 
from the reference stations and twice the number of pathologies as speci- 
mens from Aber Wrac'h. 

Abnormally high numbers of eosinophilic leucocytes (general leuco- 
cytosis) were noted in the intestinal epithelium, and sometimes surround- 
ing leydig tissue, of 15% (19 of 127) of the C. gigas examined. Almost 
all cases were in oysters from Rade de Brest. This condition was diffi- 
cult to judge. Oyster intestinal epithelium normally has some leucocytes 
between columnar cells. However, the large number of leucocytes in the 
intestinal epithelium of these 14 specimens appeared abnormally high, 
the number was considered abnormally high if the basal portion of columnar 
cells was completely, or almost completely, obscured by leucocytes. 
However, there still is some doubt about whether- this is a "pathology" 
or a normal condition. Except for the large number of leucocytes, the 
intestinal tissues appeared very healthy. 



279 



Focal aggregates of leucocytes were present in the intestinal epi- 
thelium, or adjacent to it, in 14.2% (8 of 127) of the gut tissues 
examined. One case involved a large, loose aggregation of leucocytes 
in the leydig tissue beneath the basement membrane. Another involved 
small clumps of leucocytes between the columnar epithelial cells. Like 
the general leucocytosis , this condition was difficult to judge. Leuco- 
cytes are normally present in the epithelium, but more or less scattered 
about. These clumps could be normal phagocytosis, although no foreign 
matter was ever observed in such clumps. The intestinal epithelium 
containing the above clumps appeared otherwise very healthy. 

Focal necrotic areas were present in the gut epithelium of 3 (2.3%) 
oysters examined. In two incidences, the gastric shield was involved. 
This condition was characterized by a breakdown of the structure of the 
gastric shield and/or epithelium, a concentration of debris at the 
affected area, and leucocytic inflammation of the gastric shield and/or 
epithelium. 

Ciliates were present in the gut lumen of one C. gigas. These 
ciliates were the same type as described above in the digestive gland. 

The plasmodial stage of an unidentified sporozoan was noted in the 
epithelium of a single C. gigas. The Plasmodium was amoeboid in appear- 
ance with several nuclei. The gut otherwise appeared in very good 
condition. 

Copepods were present in the stomach of 15.7% (20 of 127) of the 
specimens examined. No oysters from Aber Wrac'h bore copepods. None of 
the copepods observed were being phagocytized as was the case in the 
digestive gland. Up to three copepods were observed in some sections. 

4. Gonad . - Gonadal tissues of 130 C. gigas were examined. Gener- 
ally, two tissue samples were taken from each specimen (anterior and 
psoterior visceral mass). 

Gonadal tissues from C. gigas were a very difficult tissue type to 
assess for non-symbiotic pathologies. Possible histopathologies were 
noted in 38% (9 of 130) of the gonadal tissues examined. There were 50 
incidences of the three non-symbiotic pathology (?) types and one symbi- 
otic pathology discussed below. Only six of the 50 conditions were of 
an apparent symbiotic nature. 

Half (36 of 71) of the female gonadal tissues examined exhibited 
moderate to heavy aggregations, both focal and general, of eosinophilic 
leucocytes. This presented a perplexing problem in determining if this 



280 



represented an inflammatory response to a stressful condition and 
therefore a pathology due to such stress, or if it was a normal condi- 
tion in the reproductive cycle of C. gigas. This condition was present 
in only one Cvassostvea virginica from South Louisiana oil platforms 
(Armstrong et al., 1980) but was observed in other bivalve species (10% 
of specimens examined in association with degeneration or necrosis of 
the gonad). Eight female C. gigas from the Pacific Northwest (Sequim, 
Washington) were examined for comparison. All eight appeared to be in 
a post-spawn condition and all had heavy aggregation of leucocytes in 
the gonadal tissues. 

The spawning cycle of the C. gigas from France could not be defin- 
itely determined. Undifferentiated (could not determine if it was male 
or female), undeveloped, developing (immature), ripe (mature) and spawned 
stages were present in samples from all five of the collecting periods 
(December 1978, April 1979, August 1979, February 1980, and June 1980). 
The majority of the specimens from December 1978, however, appeared to 
be of the spawned stage at Aber Wrac'h, ripe at Aber Benoit, and undiffer- 
entiated at Rade de Brest. In April 1979, the majority of the specimens 
appeared to be in the developing stage at all three sites. The majority 
of the specimens taken during August 1979 and June 1980 appeared to be 
of the ripe stage at all three sites, although there were some spawned- 
appearing specimens from Aber Wrac'h in August 1979. The February, 1980 
collection yielded more undifferentiated and developing specimens. This 
does somewhat indicate an early winter spawn, but as already stated, all 
reproductive stages were present in samples from all five collection 
periods. 

In the C. gigas from France, 13.8% (18 of 130) of the gonads 
examined contained large numbers of leucocytes dispersed throughout 
the tissues. All 18 incidences were in female gonads (18 of 76 or 23.8%). 
This condition was present in undeveloped, developing (immature), ripe 
and post spawn ovaries. In some cases it could not be determined if the 
ovary was in a developing stage or a post-spawn stage because of the 
large numbers of leucocytes present. In some, the gonad appeared fully 
spawned (entire gonad examined contained only a few ova and ovacytes, 
follicles largely empty), while in others part of the ovary was packed 
with ova (ripe) and the other part contained few ova and ovacytes 
(spawned) and many leucocytes. In gonads with large numbers of leuco- 
cytes, all or almost all ova appeared normal (not degenerating or lysing) , 
The 29 normal ovaries (no aggregations of leucocytes present) included 
the undeveloped, developing (immature), ripe and spawned stages. 

Twenty-two of the 130 (16.6%) gonads examined contained compact 
clumps of leucocytes ranging from foci in the follicular wall to large 



281 



clumps in the ovary to foci in the leydig tissue of the testes. Nine- 
teen (86.4%) of the cases were in female gonads. Reproductive stages 
varied from undeveloped to spawned. Three of the cases were found in 
testes. 

In the general and focal leucocytoses discussed above, the differ- 
ence between the two was in the extent (small area, tight clump vs. 
general dispersion over several follicles) of inflammation, but this 
was sometimes difficult to ascertain and the two may blend together. 

Necrotic appearing areas were noted in 3.1% (4 of 130) of the gonads 
examined. These areas were characterized by cellular debris, degenerating 
ova, and leucocytosis. 

Sporozoa were present in 4.6% (6 of 130) of the specimens examined. 
Sporozoans were spherical, densely staining, and were embedded in the 
gonadal tissue. The specimens appeared to be surrounded by a small lysed 
"halo" area. 

5. Gill . - Gills from 134 C. gigas were examined for pathologies. 
Generally, three pieces of gill (consisting of both lamellae) were 
dissected from one side and oriented (when possible) to give both longi- 
tudinal and transverse sections. 

Histopathologies were noted in 31.3% (42 of 134) of the gills 
examined. There were a total of 49 cases of the six pathology types 
described below. Forty-three (87.8%) were apparently not symbiotic or 
related to a symbiotic condition. 

. Abnormally high numbers of eosinophilic leucocytes were present in 
31.3% (42 of 134) of the gills examined. In most incidences, the leuco- 
cytes were dispersed throughout several plica, but four cases appeared 
to be more focally organized in one or two plica. 

Amoebae were noted in the gills of one C. gigas. The infection 
appeared to be light as only two amoebae were found. The amoebae were 
circular in outline with a hyaline cytoplasm. The nucleus occupied 
approximately one-third of the cell. A small, spherical inclusion 
body was adjacent to the nucleus. 

The gills of four (3%) specimens examined harbored ciliates in 
their water tubules. Ciliates were somewhat crescent-shaped with tufts 
of stout cilia extending downward from the two tips. The arms of the 
crescent were sometimes turned inward so that the tips of the cilia were 
touching, giving a partially hollow, circular shape to the ciliate. Two 



282 



lateral nuclei were present. The ciliates apparently provoked an 
inflammatory response as most were surrounded by eosinophilic leuco- 
cytes in the water tubules, or the surrounding tissues contained 
abnormally high numbers of lucocytes. 

One specimen contained the plasmodial stage of a sporozoan. Multi- 
nucleate Plasmodia were subspherical to ovate. Numerous plasmodia were 
dispersed throughout the gill, but most heavily in the leydig tissue of 
the interlamellar area. 

A single copepod was found on a gill filament of one C. gigas. 

No necrotic areas were observed on the gills examined and the outer 
columnar epithelium of the specimens examined appeared healthy. The 
number of mucous glands in sections of randomly selected plica and term- 
inal grooves were counted in an effort to determine if specimens from 
Aber Wrac'h and Aber Benoit contained more active glands than those from 
Rade de Brest and lie Tudy. The results were inconclusive. The number 
of mucus cells per unit area of gill was not statistically significantly 
different among the three populations. 

6. Mantle . - Sections of mantle from 130 specimens were examined. 
Two or three pieces of mantle were dissected from specimens and oriented 
to give a transverse section across the tri-lobed edge. 

Histopathologies were noted in the mantle of 31.5% (41 of 130) of 
the specimens examined. There were a total of 47 of the three pathology 
types described below. The distribution of the pathologies among sampling 
sites was nearly equal. 

Abnormally high numbers of eosinophilic leucocytes were noted in 
35.4% (46 of 130) of the specimens examined. Thirty-eight of the inci- 
dences involved large numbers of leucocytes dispersed beneath the epi- 
thelium or in the leydig tissue. Eight cases, however, involved leuco- 
cytes which were more aggregated in clusters. 

Sporozoans were found in the mantle of a single specimen. 

No necrotic areas were found on any of the mantles examined. All 
epithelial cells appeared healthy. In an effort to determine if the 
mantle epithelium of oysters from Aber Wrac'h and Aber Benoit contained 
significantly more mucous cells than specimens from Rade de Brest and 
lie Tudy, the number of mucous cells in a high power field were counted 
at a level even with the circumpallial nerve and an area three fields 
higher. Specimens from Aber Wrac'h contained slightly more (average of 
27.5 to 34 for the five collections) mucous cells than those from Aber 



283 



Benoit (average of 20 to 32) and Rade de Brest and lie Tudy (average 
of 22 to 31). The differences were not statistically significant. 



CONCLUSIONS 



In general, oysters Cvassostvea gigas from all five collections 
and all four sampling stations appeared to be extremely healthy as 
determined by histopathological examination. Incidence of parasitic 
infestation was very low, especially when compared to incidence of para- 
sitism in C. vivginioa from the northwest Gulf of Mexico. The low 
incidence of parasitism in C. gigas from Brittany may be due to the fact 
that they are a recently-introduced mariculture species in the area. 
There probably has not been enough time for their parasites to catch 
up with them. According to Henri Grizell (personal communication), 
parasitism and disease are increasing in these oysters. 

The most prevalent pathologic lesion in C. gigas from Brittany was 
leucocytosis. In mollsucs, this condition is usually a response to 
chemical or physical irritation. It is an inflammatory defensive response. 
However, size and distribution of leucocyte populations varies greatly in 
different mollusc species under different environmental conditions. C. 
gigas generally seems to have more leucocytes than the closely-related 
C. vivginioa. Thus, the extent to which observed leucocytoses in C. 
gigas were normal or pathologic is uncertain. In any event, incidence 
of leucocytosis was similar in oysters from oil-contaminated Aber Benoit 
and Aber Wrac'h and from reference stations in the Rade de Brest and at 
lie Tudy. 

Necrosis was observed several times but no definitive cases of 
hyperplasia, neoplasia or other precancerous conditions was noted in 
any of the four oyster populations. 

There were no consistent temporal trends in incidence of pathology 
in the oysters from oiled and reference stations. Oysters collected in 
December 1978, nine months after the spill, had an incidence of patho- 
logical conditions similar to that in oysters collected in June 1980, 
twenty-seven months after the spill. One difference that may have 
obscured other effects was size. By June 1980, oysters which had been 
in the Abers at the time of the spill had grown to very large size. 
During the first year after the spill, there was little evidence of 
growth in oysters from the two Abers. During the second year, growth 
appeared normal or even accelerated. 



284 



There was also some indication, based on observations of gonadal 
condition, that oysters from the Abers had an altered reproductive cycle 
compared to reference oysters, possibly including near complete reproduc- 
tive suppression for one year after the spill. Sample sizes and frequen- 
cies were not great enough to demonstrate this convincingly. 

II. Petroleum Contamination and Biochemical 
Indices of Stress in Oysters and Plaice 

The most obvious immediate biological effect of the Amoco Cadiz 
spill was a very large kill of benthic estuarine and coastal marine 
organisms (Cross et al. , 1978). The rate of recovery of these benthic 
communities would depend on the rate and success of reproduction by the 
surviving animals in the affected area and on the success of recruitment 
from adjacent unpolluted areas. The resident benthic fauna in the oil- 
impacted area which survived the spill were undoubtedly severely stressed. 
Because of the heavy contamination of the estuarine sediments with oil 
it is highly probable that the surviving resident benthic fauna would 
continue for some time to be stressed and potential immigrants to the 
estuaries would be subjected to stress as they settled there. 

Considerable research has been conducted in recent years on sub- 
lethal physiological stress responses of marine animals to oil and other 
types of pollution (Neff et al. , 1976a; Anderson, 1977; Johnson, 1977; 
Patten, 1977; Neff, 1979; Thomas et al., 1980; Neff and Anderson, 1981). 
A variety of sublethal physiological and biochemical responses to 
pollutant stress have been described. In an ecological perspective, 
the net effect of chronic pollutant stress on marine organisms is to 
shunt limited energy resources away from growth and reproductive 
processes to maintenance and homeostatic functions. The result is 
decreased growth, fecundity and reproductive success in the stressed 
population. A variety of biochemical parameters are altered in stressed 
animals and reflect the stress-induced changes in energy balance and 
partitioning. These biochemical parameters can be used as an index 
of pollutant stress in marine animals. 

Biochemical indices of pollutant stress chosen for use in this 
investigation include hemolymph glucose concentration and adductor 
muscle-free amino acids in oysters; and blood glucose and cholesterol, 
liver glycogen and ascorbic acid, and muscle-free amino acids in plaice. 
We have discussed elsewhere the rationale for using these parameters as 
indices of pollutant stress (Thomas et al. , 1980, 1981 a,b). 



285 



When exposed to petroleum, marine molluscs and teleost fish readily 
accumulate hydrocarbons in their tissues (Neff et al. , 1976b; Varanasi 
and Malins, 1977; Neff and Anderson, 1981). Molluscs tend to release 
accumulated hydrocarbons relatively slowly when concentrations in the 
ambient medium are reduced. However, under similar conditions, teleost 
fish release hydrocarbons very rapidly. Differences in hydrocarbon 
release rate by molluscs and fish can be attributed to differences in 
ability to convert hydrocarbons to polar more readily excreted metabo- 
lites by the cytochrome P-450 mixed function oxygenase system and related 
pollutant-metabolizing enzyme systems (Varanasi and Malins, 1977; Neff, 
1979). In the present investigation, aliphatic and aromatic hydrocarbons 
were analyzed in oysters and plaice from oiled and reference stations to 
assess patterns of hydrocarbon accumulation and release and to allow for 
correlations between levels of hydrocarbon contamination of animals and 
histopathological/biochemical responses. 



MATERIALS AND METHODS 



Oysters Crassostrea gigas were collected for biochemical analysis 
on the first three sampling trips. Sampling sites were as described 
earlier in the section on oyster histopathology. Oysters were shucked 
and a sample of hemolymph was collected immediately from the heart or 
the adductor muscle and stored frozen until analyzed. Adductor muscle 
was also sampled and stored at -60°C until analyzed. 

Plaice Pleuroneotes platessa were collected by otter trawl from 
oil-contaminated Aber Benoit and Aber Wrac'h. Reference stations for 
plaice samples were as follows: December 1978, Baie de Douarnenez; 
April 1979, Loc Tudy; August 1979, February 1980, June 1980, He Tudy. 
Fish from the Baie de Douarnenez and Loc Tudy were collected by otter 
or beam trawl. Fish from He Tudy were captured by net at the sluice 
gate of the CNEXO mariculture pond and held in large circular holding 
tanks with flowing seawater until sampled. 

Samples were taken as soon as possible after capture and while the 
fish were still alive. Tissue samples included blood, muscle and liver. 
Blood samples were centrifuged to remove red blood cells. Serum, 
muscle, and liver were frozen immediately in liquid nitrogen and kept 
frozen at -60° until analyzed. 

Samples from 5-10 animals from each station and each trip were 
analyzed biochemically. Blood glucose and liver glycogen were measured 
with a Yellow Springs Instruments automatic glucose analyzer, Model 23A. 



286 



This method, based on the glucose oxidase enzymatic reaction, is highly 
specific for glucose and required only 25 ul of serum. Replicate deter- 
minations of each serum sample were performed. Total and esterified 
cholesterol in serum was determined by a cholesterol oxidase assay 
system which is both highly snesitive and specific. 

For tissue-free amino acid analysis, muscle tissue was thawed, 
weighed and homogenized in distilled water using a 2/1 ratio of distilled 
water/wet weight. Homogenates were deproteinized with 12.5% trichloro- 
acetic acid and then centrifuged. The supernates were frozen, thawed, 
and centrifuged again to remove additional TCA precipitates. The super- 
nates were then evaporated to dryness on a rotary evaporator and the 
residue dissolved in 0.2 M Citrate buffer adjusted to pH 2.2. The 
extracts were analyzed with a Beckman automatic amino acid analyzer. 
The amino acid composition of the extract and the concentration of 
individual amino acids in it were determined. Taurine/glycine molar 
ratios were computed. Variations in amino acid compositions and concen- 
trations among fish and oysters from different sampling stations were 
analyzed statistically. 

Plaice liver was analyzed for ascorbic acid. Tissue samples were 
thawed, weighed and homogenized in 3% metaphosphoric acid-8% acetic acid 
solution. After centrifugation, the supernates were analyzed immediately 
by the a,a-diperidyl technique of Zannoni et al. (1974). 

Oysters and plaice samples for hydrocarbon analysis were taken at 
the same times and places as samples for biochemical/histopathological 
analysis. Ten to twelve whole oysters were pooled for each sample. 
They were shucked and tissues were rinsed in distilled water, blotted 
dry, wrapped in hexane-cleaned aluminum foil and frozen at -60°C until 
analysis. For the April 1979 sample, whole fish were used. For sub- 
sequent samples, pooled samples of liver and muscle from 5-10 fish were 
used. Fish tissue samples were handled like oyster samples. 

Hydrocarbon analyses were performed by Dr. Paul Boehm, ERCO, 
Cambridge, Massachusetts using capillary gas chromatography /mass 
spectrometry. 



287 



RESULTS AND DISCUSSION 



Petroleum Hydrocar bons 

Concentrations of total aliphatic and aromatic hydrocarbons in 
tissues of oysters Crassostvea gigas from Aber Benoit and Aber Wrac'h, 
heavily contaminated with Amoco Cadiz oil, and from supposedly clean 
reference stations are summarized in Table 4. Reference oys-ters for the 
first two collections were Rade de Brest oysters which had been held for 
a -short period of time in concrete holding tanks on the shore of Aber 
Benoit at St. Pabu. These reference oysters were heavily contaminated 
with Amoco Cadiz oil as were the authentic Aber Benoit and Aber Wrac'h 
oysters. "Hydrocarbon status" of samples was determined by comparing 
GC peak profiles of f\ and t^ hydrocarbon fractions of tissue extracts 
to GC profiles of authentic weathered Amoco Cadiz oil. Apparently, 
sufficient oil was still leaching from the sediments of the Aber 13 
months after the spill to allow rapid and heavy contamination of oysters 
exposed to waters of the bay. Michel and Grizel (1979) reported similar 
rapid hydrocarbon contamination of oysters transplanted to stations in 
Aber Benoit and Aber Wrac'h. Subsequent reference oyster samples were 
obtained from sites which had not received Amoco Cadiz oil. They con- 
tained low levels of petroleum hydrocarbons not of Amoco Cadiz origin. 
Concentrations of total aliphatic and aromatic hydrocarbons in oysters 
from Aber Benoit and Aber Wrac'h did not vary substantially over the 
time-course of this investigation (up to 27 months after the spill) . 
The persistence of petroleum hydrocarbons in tissues of oysters probably 
represents, in part, a continuous recontamination with hydrocarbons 
leaching gradually into the water from the heavily contaminated sediments 
of the Abers. Oysters from the Baie of Morlaix, east of Aber Wrac'h and 
less heavily contaminated with Amoco Cadiz oil than the Abers, collected 
17 months after the spill, contained about half the aromatic hydrocarbons 
of Aber Wrac'h oysters. It is interesting to note that Aber Benoit 
oysters collected in December 1978 and April 1979 had a distinctly oily 
taste. Oysters sampled in August 1979 and later did not taste oily. 
Apparently, 200 ppm aromatics is not readily detected by taste, whereas 
500 ppm is. 

More detailed analysis of the aliphatic fraction of the oyster 
samples revealed some interesting trends (Tables 5-7). In all but one 
case (Aber Wrac'h, April 1979), the aliphatic fraction of Aber Benoit 
and Aber Wrac'h oysters was dominated by the low boiling aliphatics, 
C 10 ~ C 20> inciting n-alkanes, branched and isoprenoid compounds. 
This is quite unlike weathered Amoco Cadiz oil or oil in the Aber 



288 



Table 4 . Concentrations of total aliphatic and aromatic hydrocarbons 
(measured gravimetrically) in oysters Crascoctrca gigas from 
reference stations and from two estuaries contaminated with 
Amoco Cadiz oil. Status determined according to pattern and 
identity of GC peaks. 



Date/Sample 



December 1978 (9) 

Rade de Brest (reference) 
Aber Benoit 
Aber Wrac'h 



Hydrocarbon Fraction 

(pg/g dry tissue) 

Aliphatics Aromatics 



47.8 
136.7 
115.4 



208.0 
552.2 
540.0 



Status 



AC oil 
AC oil 
AC oil 



April 1979 (13) 

Rade de Brest (reference) 
Aber Benoit 
Aber Wrac'h 



153.9 


1001.0 


114.9 


690.0 


225.8 


986.1 



AC oil 
AC oil 
AC oil 



August 1979 (17) 

He Tudy (reference) 
Baie de Morlaix 
Aber Wrac'h 



39.3 


51.9 


134.6 


206.4 


101.0 


485.4 



Other oil 

Other oil 

AC oil 



February 1980 (23) 

Rade de Brest (reference) 
Aber Benoit 
Aber Wrac'h 



62 
154 

217 



87 
275 
599 



Other oil 
AC oil 
AC oil 



June 1980 (27) 

Rade de Brest (reference) 
Aber Benoit 
Aber Wrac' h 



33 
238 
132 



60 
283 

430 



Other oil 
AC oil/Other oil 
AC oil 



a ' AC oil - Amoco Cadiz oil; other oil - definitely petroleum, but cannot be 
identified as Amoco Cadiz oil. 

' month after the Amoco Cadiz oil spill, 16 March 1978. 



289 



Concentration of aliphatic hydrocarbons in tissues of oysters 
Craccoetrra tjifjar. from Aber fcenoit, Brittany Trance collected 
at different times after the Amoco Cadis oil spill. Values are 
in n<]/g dry weight (parts per billion). 







Samp 


le Date 






Compound 


Dec 197B 
(9) a 


Apr 1979 
(13) 


Aug 1979 
(17) 


Feb 1980 
(23) 


Jun 1920 
(27) 


n " c io 


NO 


32 


NS 


ND 


NO 


n-C„ 


316 


328 


NS 


162 


ND 


«-e„ 


43 


47 


ND 


44 


NO 


n-C u 


99 


31 


NS 


7 


ND 


nC 14 


394 


18 


NS 


16 


20 


Farnesane 


1,343 


776 


NS 


66 


92 


n"C 15 


22 


84 


NS 


68 


10 


n " C 16 


44 


46 


NS 


62 


62 


" C 17 


184 


61 


NS 


144 


22 


Pristane 


376 


232 


NS 


40 


22 


n " C 18 


ND 


ND 


NS 


51 


ND 


Phytane 


613 


375 


NS 


39 


122 


n'_C, 9 


47 


68 


NS 


17 


42 


n C 20 


77 


57 


ND 


7 




iTC,, 


ND 


ND 


NS 


18 


49 


nC 22 


ND 


ND 


NS 


10 


53 


nC 23 


24 


NO 


NS 


20 


57 


nC 24 


43 


ND 


NS 


21 


53 


nC 25 


55 


ND 


NS 


21 


17 


nC 26 


51 


ND 


NS 


9 


24 


n"C 27 


53 


NO 


ns 


37 


52 


n C 28 


37 


NO 


NS 


12 


11 


n " C 29 


72 


ND 


NS 


18 


66 


nC 30 


ND 


ND 


NS 


74 


343 


n-C„ 


ND 


ND 


NS 


13 


27 


nC 32 


ND 


ND 


NS 


12 


134 


nC 33 


ND 


ND 


NS 


ND 


49 


nC 34 


ND 


ND 


NS 


ND 


12 


Total Resolved Ali- 
phatics 


3,893 


2,155 


NS 


981 


1,346 



16 March 1978 
ND, not detected 
NS, no sample available. 



290 



Table 6 . Concentration of aliphatic hydrocarbons in tissues of oysters 
O\ifwoatfca (jiyac from Aber Wrac'h, Brittany Franc- collected 
at different tunes after the fltnoco Cadi* oil spill. Values are 
in ng/g dry weight (ports per billion). 









Sampl ing Date 








Dec 1978 


Apr 1975 


Aug 1979 


Feb 1980 


Jun 1980 


Compound 


(9) a 


(13) 


(17) 


(23) 


(27) 


n " c io 


46 


ND 


110 


47 


84 


n"C n 


383 


55 


759 


170 


255 


n-C 12 


86 


365 


ND 


126 


63 


n"C 13 


39 


70 


32 


NO 


15 


n ~ C 14 


36 


650 


12 


519 


35 


Farnesane 


222 


617 


953 


370 


148 


n'C 15 


13 


NO 


172 


56 


13 


n " C 16 


53 


ND 


098 


198 


31 


n"C, 7 


37 


177 


577 


218 


NO 


Pristane 


319 


52 


39 


44 


78 


n " C 18 


NO 


NO 


ND 


. 2' 


ND 


Phytane 


571 


242 


141 


194 


64 


""C,, 


187 


NO 


ND 


12 


ND 


"~ C 20 


74 


NO 


ND 


12 


ND 


n'C 2 , 


ND 


NO 


NO 


ND 


ND 


n C 22 


NO 


NO 


ND 


ND 


NO 


n " C 23 


ND 


30 


NO 


141 


ND 


n " C 24 


15 


135 


ND 


NO 


ND 


n"C 25 


15 


222 


NO 


19 


12 


n " C 26 


14 


289 


ND 


27 


ND 


n"C 27 


11 


230 


ND 


19 


ND 


n C 28 


NO 


241 


ND 


23 


ND 


n"C 29 


ND 


219 


ND 


18 


ND 


nC 30 


NO 


132 


ND 


16 


ND 


n " C 31 


ND 


NO 


ND 


NO 


ND 


n"C 32 


ND 


ND 


ND 


(ID 


ND 


Total Resolved Al i- 


2,121 


3,776 


2,893 


2,256 


798 


phatics 













' months after the Amoco Cadiz oil spill, 16 March 1978 
ND, not detected. 



291 



Table 7 . Concentration of aliphatic hydrocarbons in tissues of 

oysters rtvjnjocerv.: ™£.-;a." fron reference stations on the 
Brittany coast of France collected at different tin^s 
after the AnofO C: ;";':: oil spill. Values are in nj/n. dry 
weight (parts per Mllion). 









Sampl ing Date 






Corpound 


Dec 1978 a 


Apr 1979 a Aug 1979 b 


Feb 1920 c 


Jun 1930 c 




(<.') J 


(13) 


(17) 


(23) 


(27) 


n ~ C 10 


53 


ND 


ND 


e6 


226 


n"C n 


360 


441 


ND 


339 


4C6 


n"C 12 


15 


49 


II D 


86 


112 


iTC,, 


17 


111 


ND 


18 


9 


n"C, 4 


52 


29 


ND 


33 


18 


Farnesane 


11 


1,346 


4 


45 


35 


n"C 15 


172 


123 


29 


122 


66 


n " C 16 


139 


55 


17 


69 


41 


n"C ]7 


252 


228 


61 


81 


46 


Pristane 


18 


331 


ND 


ND 


ND 


n " C 18 


39 


HO 


NO 


58 


45 


Phytane 


117 


529 


17 


NO 


13 


n"C, 9 


40 


35 


ND 


22 


28 


n " C 20 


43 


73 


ND 


20 


24 


n"C 2 , 


42 


20 


ND 


16 


22 


n " C 22 


40 


47 


NO 


15 


23 


n"C 23 


42 


85 


21 


16 


36 


n " C 24 


49 


135 


29 


15 


45 


n"C 25 


50 


173 


33 


16 


47 


n " C 26 


56 


204 


44 


15 


55 


n-C 2? 


65 


207 


54 


20 


60 


n " C 28 


64 


167 


36 


16 


48 


n"C 2 , 


66 


165 


64 


29 


47 


n " C 30 


22 


100 


54 


50 


42 


n " C 31 


NO 


71 


59 


13 


22 


n'C 32 


ND 


ND 


ND 


ND 


8 


Total Resolved Ali- 
phatics 


1.824 


4.724 


522 


1,200 


1,604 



' from Rade de Brest, but maintained in Aber Benoit before sampling 

• from oyster rjriculture ponds of CNEX0 at lie Tudy 

' from a commercial oyster pare in the Rade de Brest 

' months after the fmoeo Cadi: oil spill, 16 March 1978 
ND, not dectected. 



292 



sediments which is dominated by higher boiling saturated hydrocarbons. 
This phenomenon is unexplained and could represent selective accumula- 
tion and/or retention of lighter aliphatics or more rapid metabolism and 
excretion of, heavier aliphatics. The most likely explanation is that 
oysters were being contaminated with hydrocarbons leaching from bottom 
sediments into the water column. Lighter aliphatics, because of their 
slightly higher aqueous solubility than heavy aliphatics, are desorbed 
more readily from sediments and therefore are more available for uptake 
by the oysters. Aliphatic hydrocarbon fractions of reference oysters 
were more uniform (Table 7). Relative abundances of C^q to C32 aliphatics 
were similar. 

There were no consistent differences in characteristics cf the ali- 
phatic hydrocarbon fraction between reference oysters and oysters from 
oil-polluted Aber Benoit and Aber Wrac'h (Table 8). With one exception 
(April 1979), alkane/isoprenoid ratios were higher in oysters from 
reference stations than in those from oil-polluted stations. Pristane/ 
phytane ratios were quite variable and without pattern. All but two 
carbon preference indices were near one indicating a petroleum origin 
for the high molecular weight aliphatic fraction. 

Composition of the aromatic fraction of oysters, as determined by 
gas chromatography /mass spectrometry, revealed a great deal about the 
origin of the hydrocarbon contamination of the oysters (Tables 9-11) . 
High concentrations of alkyl naphthalenes through alkyl dibenzothiophenes 
are characteristic of samples contaminated with crude oil. Amoco Cadiz 
oil was particularly rich in alkyl phenanthrenes and alkyl dibenzothio- 
phenes. These were the most abundant aromatics/heterocyclics in oyster 
samples from oil-contaminated Aber Benoit and Aber Wrac'h. Aromatic 
hydrocarbon assemblages of crude oil origin are dominated by alkylated 
species, whereas aromatic assemblages of pyrogenic origin are dominated 
by the unalkylated parent compound (Neff, 1979). Thus we can conclude 
that oysters from Aber Benoit and Aber Wrac'h at all five sampling times, 
and reference oysters from the December 1978 and April 1979 collections 
were heavily contaminated with crude oil, resembling the Amoco Cadiz oil. 
The other three reference samples contained some oil, but it did not 
resemble Amoco Cadiz oil. In oysters from the two Abers, there was a 
general trend for the concentration of aromatics/heterocyclics in the 
alkyl naphthalenes to alkyl dibenzothiophenes series to decrease 
slowly with time. The February 1980 samples contained higher concentra- 
tions of alkyl phenanthrenes and alkyl dibenzothiophenes than expected. 
It is possible that winter storms in December and January resuspended 
oil-contaminated sediments causing recontamination of resident oysters. 



293 



Table 8 . Characteristics of the aliphatic hydrocarbon fraction of 
oysters Cracsostrea gigas from reference stations and 
from two estuaries contaminated with Amoco Cadiz oil 



Date/Sample 



December 1980 (9) 



Pristane/Phytane 



Carbon Prefer- 
Alkanes/Isoprinoids ence Index 

(C 26" C 30 ) 



Rade de Brest (reference) 
Aber Benoit 
Aber Wrac'h 

April 1979 (13) 

Rade de Brest (reference) 
Aber Benoit 
Aber Wrac'h 

August 1979 (17) 

He Tudy (reference) 
Baie de Morlaix (reference) 
Aber Benoit 
Aber Wrac'h 

February 1980 (23) 

Rade de Brest (reference) 
Aber Benoit 
Aber Wrac'h 

June 1980 (27) 

Rade de Brest (reference) 
Aber Benoit 
Aber Wrac'h 



0.15 
0.61 
0.56 



0.63 
0.62 
0.21 



ND 

ND 

NS 

0.28 



ND 

ND 

0.23 



ND 
0.18 
1.68 



2.34 
0.18 
0.07 



0.12 
0.13 
1.00 



5.15 

ND 

NS 
0.'48 



4.37 
1.30 
0.81 



2.64 
0.28 
0.19 



1.27 

2.0 

1.57 



1.16 

ND 

1.10 



1.39 
0.93 

NS 

ND 



1.00 

1.02 

ND 



1.10 
0.61 
0.93 



294 



Table 9 . Concentration of aromatic hydrocarbons in tissues of oysters 

Ci'assostrca gigas from Aber Benoit, Brittany, France at differ- 
ent times after the Amoco Cadiz oil spill. Values are in ng/g 
tissue (parts per billion). 





Dec 1978 


Sampl ing Date 
Apr 1979 Aug 1979 


Feb 1980 


Jun 1980 


Compound 


(9) a 


(13) 


(17) 




(23) 




(27) 


Alkyl naphthalenes 


NA 


1,243 


NS 




ND 




300 


Alkyl fluorenes 


NA 


2,230 


NS 




891 




850 


Phenanthrene 


NA 


590 


NS 




43 




64 


Alkyl phenanthrenes 


NA 


17,345 


NS 


6 


,088 


3 


,014 


Dibenzothiophene 


NA 


123 


NS 




ND 




ND 


Alkyl dibenzothiophenes 


NA 


15,380 


NS 


8 


,860 


5 


,420 


Fluoranthene 


NA 


665 


NS 




150 




84 


Pyrene 


NA 


600 


NS 




150 




87 


Benz[a]anthracene 


NA 


263 


NS 




200 




ND 


Chrysene 


NA 


490 


NS 




600 




180 


Benzofluoranthenes 


NA 


570 


NS 




670 




100 


Benzopyrenes 


NA 


339 


NS 




413 




80 


Perylene 


NA 


80 


NS 




ND 




ND 


Total Resolved Aromatics 


NA 


39,918 


NS 


18 


,065 


10 


,179 



a ' months after the Amoco Cadiz oil spill, 16 March 1978. 
NA, sample not analyzed by GC/MS 
NS, no sample available 
ND, not detected 



295 



Table 10. Concentration of aromatic hydrocarbons in tissues of oysters 

Crassoctrea gigar from Aber Wrac'h, Brittany, France at differ- 
ent times after the Amoco Cadiz oil spill. Values are in ng/g 
tissue (parts per billion). 



Compound 


Dec 1978 
(9) a 


Apr 1979 
(13) 


Sampling Date 
Aug 1979 Feb 1980 

(17) (23) 


Jun 1980 
(27) 


Alkyl naphthalenes 


781 


594 


150 


ND 


10 


Alkyl fluorenes 


2,203 


1,453 


980 


560 


ND 


Phenanthrene 


89 


69 


ND 


ND 


170 


Alkyl phenanthrenes 


12,114 


14,989 


5,030 


10,089 


4,550 


Dibenzothiophene 


24 


ND 


ND 


ND 


ND 


Alkyl dibenzothiophenes 


21,748 


11,521 


9,900 


15,820 


5,530 


Fluoranthene 


258 


58 


50 


150 


70 


Pyrene 


291 


105 


65 


190 


90 


Benz[a]anthracene 
Chrysene 


] 557 


1.330 


ND 
300 


) 1 , 1 00 


63 
230 


Benzof 1 uoranthenes 


ND 


237 


260 


410 


190 


Benzopyrenes 


ND 


161 


50 


170 


140 


Perylene 


ND 


ND 


ND 


ND 


50 


Total Resolved Aromatics 


38,065 


29,517 


16,785 


28,489 


11,093 



a ' months after the Amoco Cadiz oil spill, 16 March 1978; 
ND, Not detected. 



296 



Table 11 . Concentration of aromatic hydrocarbons in tissues of oysters 
Cransoatrea qigaa from "reference" stations on the Brittany 
coast of France at different sampling times after the Amoco 
Cadiz oil spill. Values are in ng/g tissue (parts per billion). 



Sampling Date 
Dec 1978 a Apr 1979 a Aug 1979° Feb 1980 c Jun 1980 c 
COn,pOUnd (9) d (13) (17) (23) (27) 



Alkyl naphthalenes 


327 


467 


ND 


ND 


180 


Alkyl fluorenes 


689 


1,562 


ND 


ND 


180 


Phenanthrene 


129 


85 


5 


180 


350 


Alkyl phenanthrenes 


4,375 


10,679 


285 


527 


630 


Dibenzothiophene 


30 


56 


ND 


ND 


20 


Alkyl dibenzothiophenes 


3,668 


10,590 


283 


975 


675 


Fluoranthene 


220 


171 


130 


180 


200 


Pyrene 


170 


98 


130 


180 


90 


Benz[a]anthracene 
Chrysene 


\ 252 


V290 


ND 
410 


140 
350 


58 
170 


Benzofluoranthenes 


88 


48 


350 


410 


160 


Benzopyrenes 


64 


65 


140 


182 


83 


Perylenes 


ND 


ND 


ND 


ND 


ND 


Total Resolved Aromatics 


10,012 


24,111 


1,733 


3,124 


2,796 



' from Rade de Brest, but maintained in Aber Benoit before sampling 



* from oyster mariculture ponds of CNEX0 at He Tudy 
c, 

d, 



' from commercial oyster pare in the Rade de Brest 
months after the Amoco Cadiz oil spill, 16 March 1978 

ND, not detected. 



297 



Higher molecular weight aromatics, flupranthene through perylene, 
although present in small amounts in crude oil, are more characteristic 
of pyrogenic hydrocarbon assemblages (Neff, 1979). Concentrations of 
these aromatics were similar in reference and Aber oysters and there 
was no consistent pattern of temporal change. These hydrocarbons 
probably have a similar origin in all three populations, namely from 
particulate organic matter derived from smoke of wood and fossil fuel 
combustion. Several of these aromatics, including benz[a]anthracene, 
benzofluoranthenes, and benzopyrenes, are known carcinogens. Their 
presence in tissues of oysters at relatively high concentration could 
be cause for concern. 

Whole fish and muscle samples of plaice Pleuvoneates platessa 
contained low concentrations of aliphatic and aromatic hydrocarbons 
(Table 12). Most of the muscle samples contained aliphatic hydrocarbon 
distributions characteristic of oil (Tables 13-15). Nearly tenfold 
higher concentrations of aliphatics were found in liver samples than 
in muscle samples of reference plaice and plaice from the oil-polluted 
Abers. In the August 1979 samples, some of this was identified as 
petroleum. In later samples, no petroleum-derived hydrocarbons were 
detected in liver samples. The aromatic fraction showed a distribution 
pattern similar to that of the aliphatic fraction. Liver aromatic 
fractions were dominated by biogenic squalene. Liver samples also 
contained high concentrations of what appeared to be naphthenic 
(cyclic alkanes) hydrocarbons. 

Aliphatic fractions from all liver samples were dominated by hydro- 
carbons in the C21 - C30 molecular weight range. In the three liver 
samples from Aber Benoit, two of the three samples from Aber Wrac'h, and 
one reference sample, dominant aliphatics were C27 and C2g. In the 
remaining two samples, dominant aliphatics were C^r and C2g. With few 
exceptions light aliphatics, C^q - C20» were present at low or non- 
detectable concentrations in the plaice livers. 

Plaice muscle contained 1-10% of the concentration of aliphatics 
that liver did. Alkane distribution patterns in muscles varied consid- 
erably. In most cases alkanes above C24 were dominant. Concentrations 
of aliphatic hydrocarbons in muscle and liver were higher in summer 
(August 1979 and June 1980) than in winter (February 1980) , suggesting 
a seaonal cycle of tissue hydrocarbon concentration. This seasonal 
pattern was not correlated with seasonal changes in total lipid content 
of plaice tissues (Table 18). As in the oysters, there was no consistent 
difference between reference plaice and plaice from oil-contaminated Aber 
Benoit and Aber Wrac'h with respect to pristane/phytane ratio, alkane/ 
isoprenoid ratio, or carbon preference index (Table 16). 



298 



Table 12. Concentrations of total aliphatic and aromatic hydrocarbons 
(measured gravimetrically) in tissues of plaice ricuroneates 
platessa from reference stations and from two estuaries con- 
taminated with Amoco Cadiz oil. Status determined according 
to pattern and identify of GC peaks. 



Date/Sample 



April 1979 (13) D 

Whole Fish 
Loc Tudy (reference) 
Aber Benoit 
Aber Wrac'h 



Hydrocarbon Fraction 

(ug/g dry tissue) 
Al iphatics Aroma tics 



2.9 

38.0 

7.1 



91 

24 
83 



Status 



Biogenic 
Biogenic 
Small U.C.M. 



A ugust 1979 (17) 



Muscle 
Aber Benoit 
Aber Wrac'h 

Liver 
Aber Benoit 
Aber Wrac' h 



7.7 
19.9 

801.9 

1034.0 



9.0 
12.7 

235.6 
317.9 



Other oil/biogenic 
Other oil/biogenic 

Other oil/biogenic 
Other oil/biogenic 



February 1980 (23) 

Muscle 
lie Tudy (reference) 
Aber Benoit 
Aber Wrac'h 

Liver 

lie Tudy (reference) 
Aber Benoit 
Aber Wrac'h 



23 
83 
66 

736 

1510 

831 



19 
22 
12 

548 
352 
355 



Other oil/biogenic 
Other oil/biogenic 
Other oil/biogenic 

Biogenic 
Biogenic 
Biogenic 



June 1980 (27) 

Muscle 
lie Tudy (reference) 
Aber Benoit 
Aber Wrac'h 



16 

38 

146 



23 
17 

41 



Biogenic 

Other oil/biogenic 

Other oil 



Liver 

He Tudy (reference) 
Aber Benoit 
Aber Wrac'h 



1210 
1810 
1130 



723 
682 
511 



Biogenic 
Biogenic 
Biogenic 



a " biogenic - probably of biological origin; small U.C.M. - small unresolved 
complex mixture, typical of weathered oil; other oil - definitely petroleum 
but cannot be identified as Amoco Cadiz oil. 

b ' months after the Amoco Cadiz oil spill, 16 March 1978. 



299 



Table 13. Concentration of aliphatic hydrocarbons in tissues of plaice 
I'leitroncotea ' . Iroin Aber Ocnoit, Erittariy Irance, 

collected at different times after tne i\noeo CsJir. oil spill. 
Values are in ng/g dry weight (parts per billion). 









Date/Sample 










Compound 


Apr 1979(13) 
Whole Fish 


Aug 1979(17) 
Muscle Liver 


Feb 1980(23) 

Muscle Liver 


Jun 1930(27) 
Muscle Liver 


n " C 10 


MO 


ND 


ND 


ND 




ND 


ND 


MD 


nC,, 


3 


15 


NO 


6 




531 


NO 


208 


nC 12 


ND 


ND 


ND 


ND 




324 


MO 


NO 


nC, 3 


ND 


ND 


ND 


NO 




ND 


4 


MD 


nC, 4 


NO 


ND 


ND 


ND 




ND 


8 


MO 


Farnesane 


ND 


ND 


ND 


ND 




ND 


NO 


MD 


n"C 15 


3 


6 


ND 


13 




NO 


8 


MD 


nC 16 


3 


12 


ND 


14 




132 


8 


MD 


n"C„ 


9 


44 


ND 


31 




336 


13 


ND 


Pristine 


18 


12 


ND 


16 




NO 


5 


2.530 


n " C 18 


4 


47 


ND 


21 




299 


13 


MO 


Phytane 


31 


20 


ND 


2? 




NO 


5 


MD 


n"C, g 


3 


24 


ND 


15 




331 


11 


.'.0 


n " C 20 


6 


13 


ND 


29 




459 


22 


MD 


nC 21 


4 


9 


555 


39 




425 


50 


1,130 


n"C 22 


3 


10 


1.927 


44 




321 


120 


3,470 


" C 23 


3 


13 


3,695 


51 




206 


221 


6.460 


nC 24 


2 


15 


5,109 


61 




152 


324 


9,030 


n"C 25 


4 


21 


6,476 


73 




452 


436 


10.500 


nC 26 


7 


23 


8.315 


92 


2 


,530 


486 


13.700 


nC 27 


15 


31 


14,363 


95 


6 


,660 


503 


19,600 


nC 28 


8 


28 


10.552 


84 


4 


.100 


421 


15,200 


nC 29 


22 


42 


14.282 


87 


6 


.770 


359 


23,500 


nC 30 


ND 


43 


4,573 


57 




750 


299 


9.040 


nC 31 


10 


43 


4,425 


99 


1 


.430 


197 


9,150 


nC 32 


ND 


36 


1 ,414 


20 




NO 


117 


3.280 


nC 33 


ND 


NO 


NO 


ND 




NO 


86 


MD 


"C M 


NO 


ND 


ND 


ND 




NO 


51 


MD 


Total Resolved A1 i - 
phatics 


158 


507 


76,586 


991 


:•: 


.208 


3,767 


126.798 



months after the Amoco Cadiz oil spill, 16 March 1978. 



300 



Table 14. Concentration of aliphatic hydrocarbons in tissue of plaice 

. tvemnatrx nlntcar-a from Aber Wrae'h, Urittany France collected 
at different times after the Aioco Cadiz, oil spill. Values arc 
in ng/g dry weight (parts per billion). 

Date/Sample 
Apr 1979(1 3) a Aug 1979(17) Feb 1980(23) Jun 1980(27) 
Compound U'hole Fish Muscle Liver Muscle Liver Muscle Liver 



nC 10 


IID 


nC„ 


ND 


nC, 2 


ND 


n C 13 


NO 


" C, 4 


ND 


Farnesane 


ND 


n"C 15 


ND 


nC 16 


ND 


n C„ 


8 


Pristane 


10 


n ~ C 18 


3 


Phytane 


15 


n"C 19 


ND 


nC 20 


ND 


nC 21 


3 


nC 2? 


3 


nC 23 


2 


"C„ 


2 


nC 25 


3 


nC 26 


4 


nC 27 


7 


n C 28 


4 


n C 2g 


6 


" C 30 


ND 


nC 3 , 
n-C 32 


ND 
ND 


nC 33 


ND 


nC 34 


ND 


Total Resolved Ali- 


70 


phatics 



16 


ND 


105 


NO 


ND 


NO 


ND 


ND 


NO 


HD 


NO 


ND 


6 


ND 


8 


ND 


16 


ND 


ND 


NO 


7 


ND 


ND 


ND 


ND 


ND 


ND 


NO 


ND 


ND 


ND 


ND 


9 


ND 


14 


207 


23 


4,722 


34 


1 ,467 


64 


3,781 


76 


3,883 


147 


6,625 


18S 


3,032 


237 


1,747 


241 


ND 


237 


ND 


176 


NO 


1,605 


25,464 



157 3,914 



16 




152 


46 




ND 


16 




NO 


ND 




ND 


ND 




HD 


ND 




ND 


ND 




NO 


9 




NO 


28 




151 


12 




ND 


22 




ND 


17 




NO 


6 




ND 


23 




NO 


45 


1, 


040 


91 


3, 


,410 


162 


6, 


,460 


223 


9, 


,150 


335 


10,600 


328 


16 


.300 


280 


20 


,100 


255 


16 


.600 


266 


21 


.700 


254 


10 


,800 


80 


10 


,900 


100 


3 


,130 


18 


2 


.050 


17 




5S6 


2,649 


133 


,129 



months after t he Ar.oco Cadiz oil spill, 16 March 1978. 



301 



Table 15 . Concentration of aliphatic hydrocarbons in tissues of 

plaice Plvuivmcetee platcvua from reference stations on 
the Brittany coast of France at different times after 
the A"-ovo Cadiz oil spill. Values are In ng/g dry weight 
(parts per billion). 







Date/Sample 






Compound 


Apr 1979(13) a 
Whole Fish 


Feb 1930(23) 
fluscle Liver 


Jun 1980 (27) 
Kuscle Liver 


"~ C 10 


NO 


17 


99 


37 


231 


n c n 


ND 


44 


275 


75 


618 


nC )2 


ND 


11 


53 


17 


130 


n C, 3 


ND 


1 


ND 


ND 


ND 


" c, 4 


ND 


3 


ND 


1 


ND 


Farnesane 


ND 


4 


ND 


ND 


ND 


n " C 15 


ND 


11 


NO 


7 


ND 


n_t 16 


2 


16 


ND 


8 


ND 


n C 1? 


5 


32 


ND 


16 


ND 


Pristane 


3 


10 


110 


3 


ND 


n " C 18 


4 


21 


ND 


18 


ND 


Phytane 


2 


18 


ND 


6 


ND 


n'C,, 


3 


8 


ND 


7 


ND 


n " C 20 


3 


7 


80 


9 


187 


nC 2 , 


2 


8 


302 


17 


1.740 


nC 22 


2 


7 


283 


41 


5.510 


n " C 23 


2 


9 


412 


76 


1,060 


nC 24 


1 


10 


571 


no 


14,500 


n C 26 


2 


7 


771 


141 


23,600 


n ~ C 26 


2 


12 


1,150 


158 


20,000 


nc 2? 


3 


12 


2,380 


158 


21.400 


nC 28 


2 


10 


2.060 


134 


16,200 


n C„ 


6 


9 


5,270 


112 


24,200 


n " C 30 


NO 


5 


1,320 


82 


10,500 


n"C 3 , 


1 


5 


3,730 


58 


12,500 


n C 32 


ND 


ND 


749 


34 


482 


nC 33 


ND 


ND 


ND 


ND 


402 


" C 34 


ND 


ND 


ND 


ND 


1.160 


Total Resolved Al i- 
phatics 


45 


297 


19,505 


1,325 


154,420 



months after the Amoco Cadiz oil spill, 16 March 1978. 



302 



Table 16. Characteristics of the aliphatic hydrocarbon fraction 

of plaice Plcuronectcs platessa from reference stations 
and from two estuaries contaminated with Amoco Cadiz oil. 



Date/Sample 



April 1979 (13) 

Whole Fish 

Loc Tudy (reference 
Aber Benoit 
Aber Wrac'h 



Prtstane/Phytane Al kanes/lsoprenoids 



1.40 
0.59 
0.66 



2.34 
0.39 
0.45 



Carbon Preference 
Index 
{C„ 



'26 



C 30> 



3.72 
3.11 

2.41 



August 1979 (17] 

Muscle 

Aber Benoit 
Aber Wrac'h 

Liver 

Aber Benoit 
Aber Wrac'h 



0.61 
ND 



ND 
ND 



3.38 
6.14 



ND 
ND 



1.19 
1.12 



1.64 
1.70 



February 1980 (23) 

Muscle 

lie Tudy (reference) 
Aber Benoit 
Aber Wrac ' h 

Liver 

He Tudy (reference) 
Aber Benoit 
Aber Wrac'h 



0.58 
0.55 
0.64 



ND 
ND 
ND 



2.37 
1.77 

4.54 



ND 
ND 
ND 



1.13 
1.11 
1.27 



2.32 
2.34 
2.65 



June 1980 (27) 

Muscle 

lie Tudy (reference) 
Aber Benoit 
Aber Wrac'h 

Liver 

lie Tudy (reference) 
Aber Benoit 
Aber Wrac'h 



0.56 
1.00 
0.68 



ND 
ND 
ND 



5.22 
5.00 
2.07 



ND 
ND 
ND 



1.07 
1.06 
1.00 



1.45 
1.62 
1.38 



a ' months after the Amoco Cadiz oil spill, 16 March 1978. 



303 



The hydrocarbon data demonstrate convincingly the dramatic 
differences in patterns of petroleum hydrocarbon contamination of 
oysters and plaice from the same oil-contaminated Abers. Oysters 
contained high concentrations of alkanes, dominated by low molecular 
weight compounds, while in plaice, the dominant alkanes in liver 
samples were the higher molecular weight compounds. Oysters contained 
abundant petrogenic and pyrogenic aromatic hydrocarbons spanning a wide 
molecular weight range. Plaice on the other hand contained little 
true aromatic hydrocarbon. These differences undoubtedly reflect the 
markedly different capabilities of bivalve molluscs and teleost fish 
to metabolize and actively excrete petroleum hydrocarbons. Most 
teleosts studied to date have a highly active and inducible cytochrome 
P-450 mixed function oxygenase system capable of converting aromatics 
and some aliphatics to polar and more easily excreted matabolites 
(Neff, 1979). This enzyme system is absent altogether or present at 
very low activity in bivalve mollusc tissues. 

Biochemical Indices of Stress 

Total lipid concentration in tissues of oysters and plaice, deter- 
mined in connection with hydrocarbon analyses, showed no consistent 
patterns in relation to station or season (Tables 17-18). In June 1980, 
but not at other sampling times, oysters from the two oil-contaminated 
Abers contained 2-3 times as much lipid as oysters from the reference 
station. It is quite possible that this is related to differences 
between reference and Aber oysters in state of reproductive ripeness, 
and not directly to oil- induced effects. 

Heniolymph glucose concentrations in oysters were low, highly 
variable, and showed no relationship to station (Table 19). No statis- 
tically significant differences were noted in values for reference and 
Aber oysters. There was a trend at all stations toward increasing hemo- 
lymph glucose concentration between December 1978 and August 1979. 

Some patterns did emerge in serum glucose concentrations of plaice 
(Table 20). In December 1978, April 1979 and August 1979, with one 
exception, serum glucose concentrations of plaice from oil-contaminated 
Aber Benoit and Aber Wrac'h were lower than values for reference plaice. 
Two of these differences were statistically significant. The collecting 
technique (otter trawl) is highly stressful, and maximal hyperglycemic 
stress response occurs rapidly in fish (Thomas et al., 1980). The 
data suggest, not that Aber plaice were less stressed than reference 
plaice, but that they had become refractory — perhaps due to chronic 
stress — to capture-induced hyperglycemia. Inability to respond bio- 
chemically to stress has been demonstrated in plaice held in the 



304 



Table 17 . Concentration of total lipids (determined gravimetrical ly) 
in whole oysters Cracsostrea gigas from reference stations 
and from estuaries contaminated by Amoco Cadiv, oil. Values 
are in yg/g dry tissue. 



Station 



August 1979 


Feb 


ruary 1980 


June 1980 


9,775 




6,650 


5,580 


NS 




9,150 


15,900 


6,151 




4,860 


11,200 


6,188 




NS 


NS 



Reference 
Aber Benoit 
Aber Wrac'h 
Baie de Morlaix 



NS, no sample available. 



Table 18. Concentration of total lipids (determined gravimetrically) 
in tissues of plaice {Pleuronectes platessa) from reference 
stations and from two estuaries contaminated by Amoco Cadiz 
oil. Values are in yig/g dry tissue. 



Station 


Tissue 


August 1979 


Feb 


ruary 1980 


June 1980 


Reference 


Muscle 


NS 




2,310 


1,870 




Liver 


NS 




11,300 


8,770 


Aber Benoit 


Muscle 


1,921 




2,170 


1,740 




Liver 


16,729 




12,700 


11,200 


Aber Wrac' h 


Muscle 


3,278 




1,750 


1,810 




Liver 


14,725 




20,300 


4,380 



NS, no sample available. 



305 



Table 19. Hemolymph glucose concentration in oysters Craoaostrea gigas 
from reference stations and from oil-polluted Aber Benoit and 
Aber Wrac'h. Values and standard deviations are in mg glucose/ 
100 ml hemolymph. n = 8 replicates. 



Sampl ing Date 
Station Dec 1978(9) a April 1979(13) Aug 1979(17) 



Reference 5.12+3.1 13.05+2.9 23.53+4.0 

Aber Benoit 3.00+1.8 12.57+2.4 NS 

Aber Wrac'h 4.80+2.6 11.25+3.8 23.87+2.8 

NS, no sample analyzed 

a ' months after the Amoco Cadiz oil spill, 16 March 1978. 



Table 20. Serum glucose concentration in plaice Pleuronectec platesaa 
from reference stations and from oil-polluted Aber Benoit 
and Aber Wrac'h. n = 10 replicates. Values and standard 
deviations are in mg glucose/100 ml serum. 



Sampling Date 
Station Dec 1978(9) a Apr 1979(13) Aug 1979(17) Feb 1930(23) Jun 1980(27) 



Reference 158.1+11.6 149.6+23.5 160.4+36.9 27.1+19.2 37.2+12.8 

Aber Benoit 118.3+32.9 57.0+32.9* 93.7+27.3* 85.9+33.2*147.3+46.0* 

Aber Wrac'h NS 125.6+19.5 168.4+31.3 135.0+28.7*135.0+55.4* 



significantly different from reference at a = 0.05 
NS, no sample analyzed 

a ' months after the Amoco Cadiz oil spill, 16 March 1978. 



306 



laboratory (Wardle, 1972). In the last two samples, February 1980 
and June 1980, reference plaice were sampled very rapidly a^ter capture 
and their blood glucose values represent the normal unstressed values. 
Plaice from the Abers were stressed by capture and showed a hyper- 
glycemic response, suggesting some recovery of physiological function 
with time. These data show some of the difficulties in using blood 
glucose concentration as an index of stress in fish. If blood samples 
cannot be taken immediately after the fish are captured, capture- induced 
responses may obscure any due to pollution. 

Liver glycogen concentrations in fish from the last two collections 
were highly variable (Table 21). Because of extremely large standard 
deviations, no patterns could be discerned. 

Total cholesterol and high density lipoprotein (HDL) cholesterol 
concentrations in the blood of plaice were measured in sampels from the 
last two collecting trips (Table 22). The general trend was for total 
cholesterol to be elevated and HDL cholesterol concentration to be 
depressed in fish from the two oil-contaminated Abers. Several of these 
differences were statistically significant. As a result, HDL cholesterol 
as percent of total cholesterol was lower in plaice from Aber Benoit and 
Aber Wrac'h than in plaice from the reference station at lie Tudy. 

Concentration of liver-free ascorbic acid was measured in plaice 
from all five sampling trips (Table 23). In all but the February 1980 
sample, liver ascorbate concentrations in plaice from oil-contaminated 
Aber Benoit and Aber Wrac'h were substantially lower than concentrations 
in livers of plaice from reference stations. In four cases, the differ- 
ence was statistically significant. In the February collection, the 
pattern was reversed. Reference fish contained hepatic ascorbate concen- 
trations significantly lower than concentrations in livers of fish from 
the two Abers. At this time, all the reference fish were gravid females 
ready to spawn. Only a few of the fish from the Abers were in this condi- 
tion. It is highly likely that the extreme depletion of liver ascorbate 
reserves in the reference fish is the result of ascorbate mobilization 
for gonadal maturation and ovogenesis. These gravid reference fish also 
had relatively low hepatic glycogen reserves (Table 21) . 

Adductor muscle-free amino acid profiles and concentrations were 
measured in oysters from the first three collecting trips (Tables 24-26). 
Total free amino acid concentrations were always lower in adductor muscles 
of oysters from oil-contaminated Aber Benoit and Aber Wrac'h than in 
adductors of oysters from reference stations. This difference cannot 
be attributed to differences in seawater salinity between Aber and 
reference stations, since all stations had salinities in the 30-34 o/oo 



307 



Table 21. Concentrations of glycogen in the liver of plaice Pleuronectes 
platessa from a reference station at lie Tudy and from oil- 
polluted Aber Benoit and Aber Wrac'h. Values are in mg glycogen/ 
g wet weight. 



Station February 1930(23) a June 1980(27) 



Reference 4.81 + 9.05 8.45 + 7.03 



Aber Benoit 0.48 + 0.39 6.68 + 7.56 



Aber Wrac'h 14.37 + 17.42 12.35 + 12.0 



a ' months after the Amoao Cadiz oil spill, 16 March 1978. 



308 





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EX^O 




i_ 


01 


E 


01 


to ■*-» 




*/> 


CO 3 


O 




+i r— 


O 


4- 


fc ■— 


, — 


O 


<S O 


\ 




C a- 




t: 


O i 


o 


o 


t, — 


i- 




3 ■■- 


0* 


*-> 


Q) o 


+-J 


fD 




l/i 


1- 


n. E 


01 


-*-> 


o 




C 


iu i- 


o 


a> 


u ■»- 


-cz 


u 




u 


c 


<o -o 




o 


.— c 


en 


<_) 


o. « 


E 



00 
to 

+ 1 



+ 1 



+ 1 



o 
o 



*a 



309 



Table 23. Concentration of ascorbic acid in the liver of plaice 
ricuroneotcc platessa from reference stations and from 
oil-polluted Aber Benoit and Aber Wrac'h. Values are 
in nig ascorbate/g wet weight. 



Sampling Date 
Station Dec 1978(9) a Apr 1979(13) Aug 1979(17) Feb 1980(23) Jun 1980(27 ) 



Reference 136.6+22.5 137.4+16.2 131.2+15.2 5.4+2.3 69.7+21.2 

Aber Benoit 108.7+20.9 80.6+29.8* 88.3+37.1 17.3+3.5* 44.7+14.8* 

Aber Wrac'h NS 93.1+28.5* 64.3+32.5*25.1+6.0* 50.1+8.7* 



significantly different from reference at o = 0.05 . n ■ 8-10. 
' months after the Amoco Cadiz oil spill, 16 March 1978. 



310 



Table 24. Concentrations of free amino acids in the adductor muscle of 

oysters Crassor.trea gigao from a reference station in the Rade 
de Brest and from oil-polluted stations in Aber Benoit and Aber 
Wrac'h. n = 5 unless stated otherwise. 



December 1978 (nine months after spill) 



Amino Acid 


Rade de Brest 


LYS 


0.65 + 0.06 


HIS 


0.25 + 0.04 


ARG 


6.71 + 0.45 


TAU 


62.90 + 8.61 


ASP 


3.57 + 0.55 


THR 


-- 


SER 


2.85 + 1.96 


GLU 


8.81 + 1.12 


PRO 


28.41 + 6.39 


GLY 


67.69 + 3.44 


ALA 


18.98 + 1.52 


CYS 


-- 


VAL 


0.33 ++ 


MET 


0.11 + 0.01 + 


ILE 


0.15 + 0.03 + 


LEU 


0.20 + 0.03 + 


TYR 


0.12 


PHE 


-- 


NH 3 


2.55 + 0.45 


Total FAA 


201.73 + 24.21 



FAA Concentration 
(uM/g wet weight and standard deviation) 



1 'Aber Benoit 



1 ' 


Abe 


>r 


Wrac'h 


0. 


68 


+ 


0. 


11 


0. 


25 


+ 


0. 


03 


5. 


67 


+ 


1. 


05 


63. 


91 


+ 


3. 


41 


0, 


41 


+ 


0. 


12* 




2, 


,83 ++ 


3, 


,05 


+ 


0. 


.16 


5 


.14 


+ 


0. 


.09* 


24 


.01 


+ 


3, 


,01 


26 


.54 


+ 


2. 


.88* 


10 


.15 


+ 





.49 





.19 


+ 





,06 + 





.18 


+ 





.09 + 





.10 


+ 





.03 + 





.19 


+ 





.01 + 



1.02 + 0.16* 
0.53 + 0.09* 
6.68 + 0.29 
68.70 + 7.99 
0.78 + 0.06* 

3.93 + 0.52 

7.59 + 1.09 

40.82 + 9.97* 

30.56 + 7.82* 

13.50 + 2.90 



0. 


31 


+ 


0. 


21 


0. 


12 


+ 


0. 


06 + 


0. 


41 


+ 


0. 


21 + 


0, 


.33 


+ 


0. 


18 + 







,22 ++ 


2, 


.74 


+ 





,33 



2.33 + 0.19 
175.50 + 31.52 143.30 + 11.54 



-- , not detected 

' detected in two samples 
' detected in one sample 
significantly different from reference at a = 0.05 



311 



Table 25 • Concentration of free amino acids in the adductor muscle 
of oysters Crassor.trca yitiac from a reference station in 
the Rade de Brest and from oil-polluted stations in Aber 
Benoit and Aber Wrac'h. n = 5 unless otherwise stated. 

April 1979 (thirteen months after spill) 

FAA Concentration 



(uM/g wet weight and standard deviation) 



Amino Acid Rade de Brest Aber Benoit Aber Wrac'h 

0.79 + 0.15 1.04 + 0.46 

0.24 + 0.07 0.33 + 0.10 

4.31 + 0.65 4.64 + 0.72 

64.39 + 6.19 65.58 + 3.87 

1.31 + 0.58 0.92 + 0.39 

3.59 + 0.92 2.76 + 0.46 

10.27 + 1.21 10.37 + 1.11 

20.76 + 9.29 6.76 + 5.28* 

25.62 + 20.46 26.09 + 4.38 

10.33 + 2.87 • 10.94 + 0.96 
0.170 ++ 
0.26 + 0.03 + 

0.21 + 0.05 + 0.11 + 0.06 + 

0.13 + 0.01 + 0.11 + 0.03 + 

0.26 + 0.02 + 0.21 + 0.06 + 
0.134 ++ 

1.82 + 0.62 1.87 + 0.44 



LYS 


0.91 + 0.15 


HIS 


0.29 + 0.14 


ARG 


5.06 + 0.84 


TAU 


57.41 + 9.77 


ASP 


1.46 + 0.58 


THR 


— 


SER 


2.40 + 0.82 


GLU 


9.89 + 2.08 


PRO 


26.15 + 9.53 


GLY 


28.02 + 4.38 


ALA 


11.59 + 3.74 


CYS 


-- 


VAL 


— 


MET 


0.10 + 0.02 + 


ILE 


0.15 + 0.06 + 


LEU 


0.27 + 0.11 + 


TYR 


0.163 ++ 


PHE 


-- 


NH 3 


2.44 + 0.79 


Total FAA 


146.94 


--, not detected 




detected in two 


samples 


++i . 





143.60 129.86 



detected in one sample 

significantly different from reference at a = 0.05. 



312 



Table 26. Concentration of free amino acids in the adductor muscle of 

oysters Crausoc.trca girtas from a reference station at He Tudy 
and from an oil-polluted station in Aber Wrac'h. n = 5 unless 
otherwise stated. 



LYS 
HIS 
ARG 
TAU 
ASP 
THR 
SER 
GLU 
PRO 
GLY 
ALA 
CYS 
VAL 
MET 
ILE 
LEU 
TYR 
PHE 
NH 3 





Auqust 1979 


(sixteen months after spill) 








FAA Concentration 
(u!Vq wet weiqht and standard 


deviation! 


Amino Acid 


lie Tudy 


Aber Wrac'h 



0.43 + 0.20 
0.35 + 0.17 

3.82 + 0.27 
62.09 + 6.54 

2.83 + 0.92 

1.59 + 0.71 

8.07 + 4.59 

33.46 + 25.72 

41.11 + 16.13 

11.92 + 5.31 



0.29 + 0.02 
0.03 + 0.03 4 
0.11 + 0.07 4 



2.44 + 1.13 



0.21 + 0.27 
0.28 + 0.13 
6.67 + 1.83 
63.32 + 5.58 
0.97 + 0.49* 

2.73 + 1.23 

7.66 + 2.13 

28.57 + 9.74 

26.11 + 11.52 

14.09 + 3.72 



0.23 + 0.13 
0.23 + 0.30 + 
0.19 + 0.003 + 



2.43 + 0.56 



Total FAA 



166.12 



151.77 



--, not detected 

detected in two samples 

*. 

significantly different from reference at a = 0.05. 



313 



range. Dominant tissue-free amino acids in all samples were taurine 
(TAU) , glycine (GLY) , proline (PRO) and alanine (ALA) . In all samples 
from all collections and stations, taurine concentration was maintained 
nearly constant (range of means, 57.4 - 68.7 uM/g wet weight). There 
was a trend for glycine a.nd asp ar tic acid concentrations to be lower 
in adductors of oysters from the two oil-contaminated Abers than in 
adductors of reference oysters. The result was that free taurine :- 
glycine molar ratios (a recommended index of pollutant stress) were 
significantly higher in adductor muscles of oysters from Aber Benoit 
and Aber Wrac'h than in adductors of reference oysters in all but one 
instance (Table 27). Jefferies (1972) has suggested that taurine:- 
glycine ratios higher than about 2.0 in mollusc tissues may be a good 
index of stress. As indicated above, the high taurine: glycine ratios 
are attributed almost exclusively to a decrease in free glycine concen- 
tration. This, in turn, may be attributed to poorer nutritional status 
or altered patterns of amino acid metabolism in oil-stressed oysters. 

Similar patterns were observed in free amino acid profiles and 
concentrations in skeletal muscle of plaice (Table 28-32). Total free 
amino acid concentrations were much lower in plaice muscle than in 
oyster muscle, reflecting the well-developed capability of plaice to 
regulate body fluid concentration hypoosmotic to the ambient seawater 
medium. As in oyster muscle, taurine, glycine and alanine were the 
dominant free amino acids in plaice muscle. Concentrations of several 
free amino acids were statistically significantly different in muscle 
of plaice from Aber Benoit and/or Aber Wrac'h than in muscle of refer- 
ence plaice. However, there was no consistent pattern of change. Free 
glycine concentration was lower in muscle of plaice from the Abers than 
in muscle of plaice from reference stations in December 1978 and August 
1979. In February and June 1980, free taurine concentration in muscle 
of Aber Wrac'h plaice was lower than in muscle of reference fish. In 
February 1980, it was higher. Despite these as yet unexplained varia- 
tions, in seven out of nine cases where comparative data were available, 
mean free taurine: glycine molar ratios in muscle of plaice from Aber 
Benoit and Aber Wrac'h were statistically significantly different from 
ratios in muscle of reference fish (Table 33) . Because of seasonal 
variations in free taurine: glycine ratios in muscle tissue of oysters 
and plaice, it is important when using this parameter as an index of 
stress to compare values for pollutant- impacted and reference animals 
collected at the same time from nearby locations. 

Several biochemical parameters were evaluated as potential indices 
of pollutant stress in oysters and plaice from oil-contaminated Aber 
Benoit and Aber Wrac'h. Values of some of these parameters were 
statistically significantly different in populations from the 



314 



Table 27 ■ Mean free taurine:glycine molar ratios in adductor muscle 
of oysters Crassostrea gigas from reference stations (Rade 
de Brest or lie Tudy) and from oil-contaminated estuaries 
(Aber Benoit and Aber Wrac'h). Seven replicate samples 
from each station were analyzed. 



Sampling Date 
Station Dec 1978(9) a April 1979(13) July 1979(16) 

Reference 0.93 2.05 1.51 



Aber Benoit 2.25* 2.51 NS 

Aber Wrac'h 2.41* 2.51* 2.42* 

*. 

significantly different from reference sample at a = 0.05. 

NS, no sample analyzed. 

a ' months after the Amoao Cadiz oil spill, 16 March 1978. 



315 



Table 28 Concentration of free amino acids in skeletal muscle 
plaice Plcuronectes platecaa from a reference station 
in Baie de Douarnenez and from oil-polluted Aber Benoit. 
n = 5 unless stated otherwise. 

December 1973 (nine months after spill) 

FAA Concentration 
(pM/q wet weight and standard deviation) 
Amino Acid Baie de Douarnenez Aber Benoit 

LYS 0.28 + 0.10 1.47 + 0.76* 

HIS 0.40 + 0.04 0.53 + 0.14 

ARG 0.37 + 0.09 0.26 + 0.08 

TAU 11.33+2.68 11.23+3.06 

ASP 

THR 0.84 + 0.19 0.66 + 3.06 

SER 0.92 + 0.68 0.71 + 0.18 

GLU 0.35 + 0.13 0.15 + 0.06 + 

PRO 0.27 + 0.11 0.48 + 0.18 

GLY 11.86 + 4.81 5.58 + 1.48* 

ALA 2.91 + 0.99 1.34 + 0.09* 

CYS 

VAL 0.12 + 0.01 + 0.23 + 0.17 + 

MET 0.07+0.01 + 0.07+0.02 

ILE 0.06 + 0.01 + 0.11 + 0.07 

LEU 0.11 + 0.01 + 0.13 + 0.08 

TYR 

PHE 

NH, 6.36 + 0.39 6.29 + 0.34 



Total FAA 29.89+9.86 22.95+6.58 



--, Not detected 

* two samples 

' significantly different from reference at a = 0.05. 



316 



Table 29 • Concentration of free amino acids in skeletal muscle of 
plaice Pleuroncatec platessa from a reference station at 
Loc Tudy and from oil -polluted Aber Benoit and Aber Wrac'h. 
n = 5 unless otherwise stated. 

April 1979 (thirteen months after spill) 

FAA Concentration 

(^M/g wet weight and standard deviation) 

Amino Acid Loc Tudy Aber Benoit Aber Wrac'h 

0.18 + 0.11 
0.56 + 0.35 

8.94 + 2.43* 
0.06 + 0.02 
0.59 + 0.27 
0.66 + 0.16 
0.30 + 0.05 
0.56 + 0.31 
8.86 + 3.01 
1.15 + 0.24* 

0.12 + 0.01 + 
0.06 + 0.02 + 
0.07 + 0.01 + 
0.06 + 0.05 + 



5.30 + 1.24 



LYS 


0.47 


+ 0.23 


0.88 + 0.21* 


HIS 


0.92 


+ 0.31 


0.99 + 0.21 


ARG 




-- 


0.21 + 0.12 + 


TAU 


14.67 


+ 3.19 


11.41 + 1.38 


ASP 


0.13 


+ 0.06 


0.05 + 0.03 


THR 


0.89 


+ 0.31 


1.21 + 0.58 


SER 


0.77 


+ 0.19 


0.97 + 0.09 


GLU 


0.29 


+ 0.14 


0.29 + 0.07 


PRO 


0.25 


+ 0.03 


0.87 + 0.24* 


GLY 


7.38 


+ 0.47 


9.81 + 1.50 


ALA 


1.77 


+ 0.28 


1.28 + 0.18 


CYS 




-- 


0.12 ++ 


VAL 




— 


0.11 + 0.01 + 


MET 


0.49 


+ 0.01 + 


0.06 + 0.02 + 


ILE 


0.09 


+ 0.03 + 


0.04 + 0.03 + 


LEU 


0.08 


+ 0.03 + 


0.11 + 0.02 + 


TYR 




-- 


-- 


PHE 




-- 


-- 


NH 3 


4.69 


+ 0.74 


5.07 + 0.61 


Total FAA 


28.21 


28.41 


--, not detected 








detected in two 


samples 





22.18 



detected in one sample 

significantly different from reference at o = 0.05 



317 



Table 30. Concentration of free amino acids in skeletal muscle of 
plaice Pleuroncctes platessa from a reference station at 
lie Tudy and from oil-polluted Aber Benoit and Aber Wrac'h. 
n = 5 unless otherwise stated. 

August 1979 (seventeen months after spill) 



FAA Concentration 
(tiM/g wet weight and standard deviation) 



Amino Acid He Tudj, Aber Benoit 



LYS 0.96 + 0.65 0.64 + 0.33 

HIS 0.97 + 0.66 0.66 + 0.12 

ARG 0.17 + 0.02 + 

TAU 9.28 + 1.22 10.08 + 1.32 

ASP 0.03 + 0.01 + 0.05 + 0.03" 

THR 0.36 + 0.15 0.48 + 0.07 

SER 0.27 + 0.22 0.41 + 0.22 

GLU 0.10 + 0.01 0.18 _ 0.05 + 

PRO 0.50+0.03 + 0.74+0.20 + 

GLY 9.96 _ 3.40 6.57 + 3.14 

ALA 1.67 + 0.81 0.86 + 0.26 

CYS -- 0.18 + 

VAL 

MET 0.03 + 0.04 + 0.39 + 0.53 + 

ILE 0.41 + 0.03 + 0.07 + 0.03 + 

LEU 0.04 + 0.001 + 0.10 + 0.08 + 

TYR 

PHE 

NH, 5.65 + 0.58 5.38 + 2.19 6.34 + 1.27 



Aber 


Wrac ' h 


1. 


40 


+ 


0. 


70 


1. 


50 


+ 


0. 


21 


0. 


21 


+ 


0. 


01 + 


8. 


01 


+ 


1. 


16 


0. 


06 


+ 


0, 


.05 


0, 


.65 


+ 


0. 


,24 


0. 


.47 


+ 


0, 


.25 





.17 


+ 





,11 


1, 


.78 


+ 


1 


.41 


3 


.70 


+ 


1 


.56* 


1 


.27 


+ 





.29 





.16 


+ 





.15 + 





.17 


+ 





.09 + 





.11 


+ 





.09 + 





.16 


+ 





.n + 



Total FAA 24.40 21.39 20.29 

--, Not detected 

' detected in two samples 

detected in one sample 

*» 

significantly different from reference at a = 0.05. 



318 



Table 31. Concentration of free amino acids in skeletal muscle of plaice 

Plcuroneateo platcr.sa from a reference station at He Tudy and 

from oil-polluted Aber Benoit and Aber Wrac'h. n = 8 to 10 unless 
otherwise stated. 

February 1930 (23 months after spill) 

FAA Concentration 

(pM/g wet weight and standard deviation) 

Amino Acid lie Tudy Aber Benoit Aber Wrac' h 

LYS 0.57+0.40 0.95+0.58 0.55+0.42 

HIS -- 0.50 + 0.21{1)^ 0.70 + 0.39 

ARG 

TAU 7.55+2.90 12.57+3.38* 12.36+2.33* 

ASP 0.20 + 0.15(8) 

THR 0.33+0.11 0.63+0.20* 0.78+0.42* 

SER 0.70+0.52 0.93+0.50 0.79+0.36 

GLU 0.57+0.20 0.24+0.13* 0.27+0.10* 

PRO — — 1.51 + 0.72(3) 

GLY 7.42+2.64 15.49+7.96* 18.61+5.32* 

ALA 3.70+0.74 1.63+0.59* 1.53+0.40* 

CYS 

VAL 

MET 0.32 + 0.08(5) — 0.03(1) 

ILE 0.21 + 0.14(7) 

LEU 0.29 + 0.17(7) — 0.16(1) 

TYR 

PHE 

NH 3 NA NA NA 



Total FAA 20.86 32.94 38.80 

--, not detected 

NA, not analyzed 

* 
' significantly different from reference at a = 0.05 

' number of samples in which amino acid was detected. 



319 



Table 32 . Concentration of free amino acids in skeletal muscle of plaice 
Plcuronectes platcvsa from a reference station at lie Tudy and 
from oil-polluted Aber Benoit and Aber Wrac'h. n = 8 to 10 unless 
otherwise stated. 

June 1980 (twenty-seven months after spill) 



FAA Concentration 

(uM/g wet weight and standard deviation) 

Amino Acid He Tudy Aber Benoit Aber Wrac'h 



--, not detected 

NA, not analyzed 
* 
' significantly different from reference at a = 0.05 

' number of samples in which amino acid was detected. 



LYS 0.34+0.30 0.63+0.52 1.05+0.32* 

HIS 0.29 + 0.13 1.39 + 0.63* 1 .87 jf 0.46* 
ARG 

TAU 16.92+3.96 12.37+3.63 11.81+2.30* 

ASP 0.13 + Q.}A{7) } 0.08+0.03 0.06+0.02 

THR 0.33+0.17 0.87+0.37 0.77+0.35 

SER 0.80+0.32 0.59+0.38 0.63+0.37 

GLU 0.26+0.19 0.25+0.08 0.19+0.06 

PRO 0.24+0.28 1.73+2.34(9) 2.30+2.33(9) 

GLY 2.50+2.08 14.65+6.95* 8.77+4.52* 

ALA 2.26+0.60 1.28+0.43* 1.07+0.32* 
CYS 

V AL 0.34+0.37(3) 0.15+0.02(6) 0.16+0.02(6) 

MET 0.15+0.08 0.12+0.02(9) 0.14+0.06(9) 

ILE 0.12+0.18 0.08+0.04 0.09+0.02(8) 

LEU 0.16+0.25 0.16+0.05 0.16+0.03(7) 

TYR 

PHE 

NH 3 NA NA MA 



Total FAA 24.84 35.37 29.07 



320 



Table 33. Mean free taurine: glycine molar ratios in skeletal 

muscle of plaice Pleuroncates platessa from reference 
stations (Baie de Douarnenez , Loc Tudy, or He Tudy) 
and from oil-contaminated estuaries (Aber Benoit and 
Aber Wrac'h). Seven or ten replicate samples from 
each station were analyzed. 

Sampling Date 
Station Dec 1978(9) a Apr 1979(13) Aug 1979(17) Feb 1980(23) Jun 1980(27) 

Reference 0.96 1.99 0.93 0.66 1.35 

Aber Benoit 2.10* 1.16* 1.53* 0.81 0.84 

Aber Wrac'h NS 1.01* 2.16*. 1.02* 6.77* 



significantly different from reference sample at a - 0.05. 
NS, no sample analyzed. 

a ' months after the Amoco Cadiz oil spill, 16 Mc.rch 1978. 



321 



oil-polluted Abers and from nearby reference stations. These may 
be useful indices of pollutant stress. They include blood cholesterol/ 
HDL cholesterol, liver ascorbic acid, and skeletal muscle-free amino 
acid ratios in fish; and adductor muscle-free amino acid ratios in 
oysters. Blood glucose also has potential as an index of stress in fish, 
if the fish can be captured and blood samples taken very quickly. 
Alternatively, useful information can be obtained if degree and duration 
of capture- induced stress can be standardized for reference and experi- 
mental fish. In such a case, the index of chronic pollutant stress is 
hypoglycemia, reflecting a loss or diminuation of the capacity of the 
hypophyseal-interrenal system to respond to stress. 

Several of the alterations in biochemical parameters in oil-polluted 
fish and oysters are indicative or symptomatic of poor nutritional status 
(e.g., depressed muscle glycine, depletion of liver glycogen and ascor- 
bate, etc.). This may be related to histopathological lesions, reported 
by Haensly and Neff in this publication in the gut and liver of plaice 
from the oil-contamianted Abers. 

One difficulty in using biochemical and histopathological parameters 
as indices of pollutant stress is that one is not always certain that 
animals from the impacted and reference sites are from the same popula- 
tion and therefore can be compared biochemically and histopathologically. 
The only way to establish convincingly that differences observed in indi- 
cator parameters in reference and impacted populations are due solely or 
primarily to the pollution incident under investigation, is to have 
comparative data collected before the pollution incident. This usually 
is not available. The oysters used in this investigation are a recently 
introduced species Crassostrea gigas and are from a common breeding 
stock throughout Brittany. Genetic differences between reference oysters 
and oysters from the Abers are therefore extremely unlikely. However, 
the extent to which plaice from the west and south coast of Brittany 
(reference sites) mix and interbreed with plaice from the northwest 
coast (site of the Abers) is not known. Some intermixing undoubtedly 
occurs. It seems likely, therefore, that many of the differences we 
have reported between oysters and plaice from the Abers and those from 
reference stations are attributable directly or indirectly to impacts 
of the Amooo Cadiz oil spill. 

There has been substantial improvement in condition of oysters 
and plaice in the Abers during the timecourse of this investigation 
(up to 27 months after the spill). Recovery is still not complete, 
however . 



322 



A most interesting observation from our investigations is that 
oysters, which were heavily contamianted by the oil spill and remained 
so for the duration of the investigation, showed little evidence of 
histopathological or biochemical damage, whereas plaice from the Abers, 
although not heavily contaminated with oil, showed evidence of serious 
and progressive histopathological and biochemical damage. This may 
be due to differences in the sensitivity of molluscs and fish to petrol- 
urn. However, an alternative hypothesis is that the metabolites of 
petroleum hydrocarbons, particularly of the polycyclic aromatic hydro- 
carbons, are much more toxic than the unmetabolized parent compounds 
and cause much of the damage in a chronic pollution situation. It is 
well-established that the phenolic, epoxide and diol metabolites of 
polycyclic aromatic hydrocarbons are much more elctrophilic and bio- 
logically reactive than the unoxygenated parent compounds (Neff, 1979). 
Since oysters have little or no capability to oxygenate polycyclic aro- 
matic hydrocarbons to reactive metabolites, they are quite tolerant to 
oil. Fish on the other hand have a highly active mixed-function oxygen- 
ase system and so rapidly convert polycyclic aromatics to reactive 
metabolites which cause tissue damage. This hypothesis warrents further 
investigation. 



323 



REFERENCES CITED 

Anderson, J.W. , 1977, Responses to sublethal levels of petroleum hydro- 
carbons: are they sensitive indicators and do they correlate with 
tissue contamination? pp. 95-114 In: D.A. Wolfe (ed.) Fate and 
Effects of Petroleum Hydrocarbons in Marine Organisms and Ecosystems. 
New York: Pergamon Press. 

Armstrong, H.W. , J.M. Nef f, and R. Sis, 1980, Histopathology of benthic 
invertebrates and demersal fish: central Gulf of Mexico oil plat- 
form monitoring study. U.S. Dept. of Interior, Bureau of Land 
Management, New Orleans, LA. 132 pp. 

Blanton, W.G. and M.C. Robinson, 1973, Some acute effects of low-boiling 
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Ernst, V.V., J.M. Neff, and J.W. Anderson, 1977, Effects of the water- 
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Eurell, J. A. and W.E. Haensly, 1981, The effects of exposure to water- 
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Haensly, W.E. and J.M. Neff, 1982, Histopathology of Vlewcomctes platessa 
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Hawkes, J.W. , 1977, The effects of petroleum hydrocarbon exposure on the 
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Hess, W.N. (ed.), 1978, TheAmoco Cadiz oil spill. A preliminary report. 
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Hodgins, H.O., B.B. McCain, and J.W. Hawkes, 1977, Marine fish and 

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McKeown, B.A. and G.L. March, 1978, The acute effect of bunker C oil 

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327 



RETABLISSEMENT NATUREL D'UNE VEGETATION DE MARAIS MARITIMES ALTEREE 
PAR LES HYDROCARBURES DE L' AMOCO-CADIZ :MODALITES ET TENDANCES 

par 

Jacques E. LEVASSEUR et Marie-L. JORY 

Laboratoire de Botanique Generale 
Campus Scientifique de Beaulieu 
35042 -RENNES Cedex - France 

RESUME 

Le retabLissement de La vegetation des marais de I'lle Grande partieL- 
Lement detruite par Les hydrocarbures est signi f i cativement engage et ce depuis 
1980. Les modaLites et La chronoLogie du retabLissement sont fonction de La domi- 
nance reLative, en chaque point, de deux processus : regeneration in situ d'indi- 
vidus perennes, germination de graines et semences produites sur pLace ou dans Le 
voisinage. La coLonisation est surtout Le fait d'especes annueLLes, aLors que La 
germination des especes perennes est tres peu frequente, sauf dans Les zones abri- 
tees a substrat meubLe et propre. ELLe est toutefois raLentie ou nuLLe dans Les 
secteurs exposes aux effets directs de La maree et/ou pietines intensement Lors 
du nettoiement de 1978. CeLa justifie Les efforts de restauration voLontaire, au 
moyen de pLantation^ tentes dans de teLs sites et dont un des interets est d'ac- 
ceLerer Les phenomenes de depot des sediments et des semences. 

D'autre part, des especes initiaLement "resistantes" presentent actueL- 
Lement une sensibiLite marquee a La poLLution endogee toujours activecequi se tra- 
duit par Le decLin et, a terme, par La disparition sur de Larges espaces de popu- 
Lations entieres ( cf. Juncus mari timus Lam.), 

Ainsi, ces processus, agissant simuLtanement ou successivement condui- 
sent-iLs a des sequences de retabLissement variees, a des stades transitoires (?) 
marques par une redistribution spatiaLe des especes qui s'ecarte notabLement de 
La distribution anterieure. 



ABSTRACT 

Recovery of iLe Grande saLt-marsh vegetation, partiaLLy destroyed by 
hydrocarbons has been signi f i cant Ly started up since 1980. Ways and timing of re- 
covery are due to the reLative dominance, in each point, of two processes viz. in 
situ regeneration of perenniaL individuaLs, germination of seeds producted near or 
on the site. CoLonisation is mainLy due to annuaL species whi Le germination of 
perenniaLs is a rare event, except in shades pLaces with Loose and cLean substrate. 
However, it is impeded either in tide exposed points or in formerLy heavi Ly tram- 
pLed pLaces. 

So, efforts of voLontary restoration are justified in such Locations ; 

pLanting acts besides by the speeding up of the aggregation of sediments and seeds 

cLose to the transpLants. 

329 



In an other hand, some species, initially "resistant" show a marked 
sensibility to underground actual pollution and consequent ly, large populations 
may decline or even die ( cf. Juncus maritimus Lam.). 

Finally, these processes, acting in simultaneous or successive manners, 
will lead to varied recovery sequences, to transitory (?) stages characterized 
by a spatial species redistribution which may be quite different from the origi- 
nal pattern. 



MOTS-CLES: Retabli ssement, regeneration, restauration, successions secon- 

daire et primaire, pollution par les hydrocarbures, nettoiement, 
vegetation de marais maritimes. 

KEY WORDS: Recovery, regeneration, restoration, secondary and primary 

succession^ hydrocarbons pollution, cleaning up, salt marsh 
vegetation. 



330 



INTRODUCTION 



Le retablissement d'un couvert vegetal perturbe est un processus 
complexe qui recouvre des realites et presente des modalites tres diver- 
ses, d'autant que les causes perturbantes n'ont pas eu le meme impact 
suivant les lieux et suivant les especes composant le tapis vegetal 
(Baker, 1979 ; Levasseur et al , , 1981). 

Les marais maritimes constituent un ensemble heterogene, qui quoi- 
que fondamentalement organise en habitats Stages, aux conditions meso- 
logiques varices, supporte une vegetation qualitativement ou dans les 
espaces intrazonaux, quantitativement variee. Cependant, etant donne qu'il 
s'agit d'environnements physiquement determines, surtout dans les par- 
ties moyennes et basses des marais, la diversite specif ique est f aible, 
ce qui signifie qu'une perturbation peut avoir un effet drastique sur 
des communautes vegetales et ceci d'autant plus qu'elles seront pauci- 
specifiques et/ou particulierement sensibles, de par leurs composantes, 
a une cause perturbatrice particuliere, 

Ayant dans un travail anterieur (Levasseur et al., 1. c . ) detaille 
cet aspect des choses, nous ne presenterons, dans cette communication, 
que quelques donnees relatives au retablissement de la vegetation au 
cours des trois annees ecouleesjet ceci aussi bien dans les espaces non 
modifies par l'homme que dans ceux qui ont ete transformes du fait des 
operations de nettoiement. 

Pour ce faire, nous utiliserons les documents suivants, quoique non 
exhaustifs des differents cas de figures rencontres : 

- cartographie chronologique d'un marais choisi pour sa diversite 
intrinseque initiale, mais aussi pour la diversite des perburba- 
tions 1 'ayant affecte depuis mars 1978 ; 

- transects permanents, regulierement releves depuis 197 1 ? et desti- 
nes, au plan*populations vegetales, a illustrer a la fois la chro- 
nologie des reprises, le developpement vegetatif ulterieur, les 
reorganisations spatiales interclones etla colonisation directe 
par les individus nouveaux. 



LE RETABLISSEMENT : DEFINITION ET PROCESSUS GENERAUX 

Definition 

II y a lieu de distinguer entre : 

1 - le retablissement dans un marais donne du couvert vegetal, qui 
se traduit par une cicatrisation se deroulant non necessairement lineai- 
rement dans le temps et non synchroniquement dans l'espace et dont la 
duree probable, pour etre menee a son terme,est fonction de nombreux pa- 
rametres y essentiellement : 



331 



- le degre de destructuration et/ou de destruction initiales ; 

- les nouvelles conditions ecologiques (p. ex. la permanence, 
dans et sur le sol, et sous differentes formes, de quantites 
importantes de petrole est un nouveau facteur de l'environne- 
ment). 

Cette cicatrisation ( i. e. gains en recouvrement) est independan- 
te des voies su ivies et des moyens mis en oeuvre. 

Elle peut quelquefois avoir pour consequence la constitution d'un 
peuplement vegetal qualitativement et/ou structuralement different du 
peuplement d'origine-mai's la dimension temps manque pour evaluer le de- 
gre de permanence de 1'etat atteint au moment du constat car, en cette 
matiere, tous les etats sont conditionnels et contractuels ! 

2 - le retablissement d'une communaute vegetale particuliere, en 
qualite et en structure, dans un lieu donne, Cet etat, necessitant des 
references anterieures precises est beaucoup plus difficile a. evaluer 
que le premier cite, immediatement apprehendable car il s'agit du degre 
de recouvrement par la vegetation, au temps t, d'un espace donne. 

Cependant, le retablissement apres perturbation d'une vegetation 
peut etre estime, lorsqu'il est compris comme etant la reparation natu- 
relle des dommages subis, au moyen de constats etablis a intervalles 
reguliers. 

Processus generaux. 

Le retablissement est a la fois un processus et un resultat, lors- 
que l'on consider e qu'il est mene a terme. De ce point de vue il est 
largement engage en de nombreux sites et meme localement acheve. Mais 
sous ce phenomene,en depit des expressions spatiales et des chronolo- 
gies si diverses actuellement, se retrouvent les memes mecanismes. 
Ceux— ci sont fondamentalement au nombre de deux auxquels il faudrait 
ajouter les actions volontaires de restauration par plantations : 

Successions secondaire d'une part, primaire d' autre part. En fait, 
la distinction dans un lieu donne de ces deux processus est loin d'etre 
nette car frequemment ils agissent synchroniquement et non sequentielle- 
ment et de plus ils inter-et retroagissent quelquefois continuement . 

La reparation naturelle des destructions peut se faire soit dans un 
premier temps a partir de la regeneration in situ d' elements vivaces 
ayant survecu, que ceux-ci soient situes a l'interieur de la zone attein- 
te ou peripheriquement , soit, dans un second temps, par des implantations 
nouvelles a partir de migrules provenant d'individus ou de clones situes 
en dehors de la zone interessee^ou d'individus ou de portions de clones 
autochtones ayant pu poursuivre ou retrouver un cycle phenologique nor- 
mal ou ayant retrouve cette capacite apres un delai plus ou moins long 
de survivance en vie ralentie. Dans ce cas, il s'agit alors d'une colo- 
nisation interstitielle et/ou sequentielle puisque commandee spatiale- 
ment par l'ordre de reapparition, la localisation, le nombre et la na- 
ture des individus vivaces ayant survecu, raais aussi par les conditions 
ecologiques regnant dans le lieu. 

Ainsi, un processus de regeneration qui a notre sens se rapporte 
d'abord aux especes perennes implique la poursuite normale du cycle vege- 
tatif d'individus epargnes et la reprise de developpement epige d'indi- 
vidus survivants du fait de dispositions morphologiques particulieres ou 
de conditions d'habitats plus favorables. 

332 



Nous distinguerons alors les phases suivantes 



1 - Apres une periode plus ou mo ins longue de vie ralentie, repri- 
se du cycle phenologique normal 

2 - Extension vegetative eventuellement centrifuge consecutive ou 
concomittante de la premiere phase et/ou formation de graines et senten- 
ces viables 

3 - Poursuite du processus si les conditions mesologiques restent 
adequates et si les conditions d' interactions coenotiques (concurrence) 
le permettent. 

Le second processus de colonisation (1, e^ succession primaire s_^ 1. ) 
implique : 

1 - La formation de graines et sentences dans, en peripheric ou a. 
l'exterieur de *zone concernee 

2 - La non-exportation pour celles produites sur place ou inverse- 
ment l'accessibilite <*es liaux pour les autres 

3 - Des conditions de germination et de developpement lavorables 

4 - Le maintien de ces conditions auxquelles vont s'aj outer les con- 
ditions coenotiques, les unes et les autres variant avec le temps, dans 
l'espacejdu fait du processus fondamental de retroaction. 

La colonisation peut aussi etre le fait de fragments vegetatifs de- 
taches de pieds-meres, dans le lieu ou y ayant acces par le jeu des cou- 
rants. (cf. dispersion actuelle,qui utilise ces deux modalitesjde Sparti- 
na cf. anglica , dans le marais 2, mais aussi, a. l'Ouest du pont, dans le 
marais 4) . 





• e mblai s 



localisation des transects 



Figure 1. Carte de localisation des marais de l'lle Grande. 

333 



INVENTAIRE SOMMAIRE DES SITUATIONS HERITEES 

A la fin de 1978, les cinq situations suivantes ont ete distinguees, 
sur la base du recouvrement ou non par les hydrocarbures, de l'intensite 
du pietinement ou du passage repete d'engins lors du nettoiement interve- 
nu en 1978, des operations connexes de ce nettoiement telles le decapage 
au bulldozer de la couche superf icielle du sol ou l'etablissement de 
remblais a 1' emplacement des fosses de stockage du petrole, 

Groupe A : 1) zones non touchees ou touchees seulement marginalement 
par l'epandage d' hydrocarbures, mais qui ont pu etre secondairement pie- 
tinees. 

Groupe B : zones- ayant ete soumises a 1' impact direct du petrole. 

2) zone petrolee mais non nettoyee Intensivement ( i . e . 
sans pietinement important ayant entraine une compaction durable des 
couches superieures du sol) . 

3) zone petrolee et nettoyee intensivement. 

Groupe C : zones profondement modifiees par rapport a leur statut 
anterieur : 

4) zones remblayees (mort-terrains, sediments meubles) 

5) zones etrepees au bulldozer. 



Caracterlstiques generales de ces zones . 

Situation 1) Secteurs non atteints ou peu atteints par les hydrocarbures 
du fait de leur situation topographique ou des dispositions 
prises, immediatement apres la catastrophe (cf . marais 1 et 
2, a l'Est du pont) , 

Localisation : 

Parties internes des marais ou dunes hordieres 

Processus en cours : 

Succession secondaire de cicatrisation dans les zones pietinees. 

Situation 2) Territoires pollues mais non ou peu pietines. Depot initial 
de petrole sur les parties aeriennes des plantes et sur le 
sol formant ensuite sur celui-ci un revetement coherent qui 
se desquame localement avec le temps, dans les sites exposes 
(modalite 1). Depot intrasedimentaire de petrole ; celui-ci 
encore actuellement sous forme semi-liquide dans les chenaux, 
dans la partie haute de la slikke, mais aussi en haut-schorre, 
dans les zones saturees en eaux douces par les sources venant 
du domaine terrestre et qui constituent des marecages supra- 
littoraux saumatres comme dans le marais 6 (modalite 2) . 

Processus en cours : 

Tres variables. Successions secondaires ayant debute des l'autom— 
ne 1978 et qui sont caracterisees essentiellement par une 
regeneration in situ d'especes perennes epargnees et survi- 
vantes. Lorsque la destruction du tapis vegetal a ete plus 
complete, il y a possibilite de colonisation directe par 
des elements allochtones si les conditions s'y pretent. 
II y a ainsi possibilite d'une succession primaire inter- 
stitielle. 

334 



Situation 3) Territoires fortement pietines et/ou sourais a. des passages 
d'engins, notamment d'engins chenilles qui detruisent les 
organes endoges de perennance. 

Destruction quasi-totale de la vegetation ; survivance 
d'un tres faible pourcentage(quelquefois inferieur a 5 %) 
d'itidivi'dus de type geophyte a rhizome et hemicryptophyte 
a souche. 

Compaction secondaire forte avec pour consequences le 
tassement du sol et la penetration forcee du petrole dans 
ses premiers centimetres. Peu de changements en trois ans 
de cet etat, sauf en mode expose ou des delitations et 
desquamations se produisent,sauf encore dans les zones pro— 
ximales soumises a sedimentation. 

Localisation : 

Cette situation se rencontre surtout dans les parties des marais 
les plus proches des chenaux et criques, la ou etait effec- 
tue le pompage du petrole. Les communautes les plus frequem- 
ment destructurees ou detruites sont les suivantes : 
peuplement a Spartina maritima, 

" a dalicornia perennis , 

" a Halimione portulacoides , 

a. Puccinellia maritima et Trlglochin maritima , 
p.p. " a Juncus maritimus du schorre moyen (vegetation 
a Limonium vulgare e t Plantago mari'tima .f*) 

Processus en cours : 

Le retablissement de la vegetation, par des voies naturelles y 
est tres lent sinon nul, actuellement encore ; succession 
secondaire possible a partir des elements epargnes, mais 
ceux-ci sont en quantite insu.f f isante pour permettre une 
cicatrisation rapide de ces lieux. En fait la reprise de 
la vegetation y est quasi-nulle, Le retablissement d'un cou- 
vert vegetal ne peut etre que la. consequence d'une succes- 
sion primaiTe en quelque sorte obligatoire dans le lieu, 
mais qui pour de nombreux sites n'est encore que potentielle, 
ou bien encore d'operations de restauration par plantations 
ad hoc d'especes vivaces. 

Situation 4) Remblais 

Les parties de marais remblayees sont localisees a. l'empla- 
cement de fosses, ce qui explique les tassements ulterieurs 
observes depuis 1980, et la reintegration de certains de ces 
espaces dans le domaine maritime s^. J L . (marais 2 p. ex.) 

Processus en cours : 

Succession primaire obligatoire. D'ailleurs tres rapidement ini- 
tiee et qui, en 1981, en est deja au stade developpement ve— 
getatif horizontal d'especes vivaces- surtout Puccinellia 
maritima . II faut noter que dans ces lieux la germination 
d'especes vivaces a ete observee et que la colonisation 
s'est faite a partir de graines et semences ayant eu acces 
au site et ayant pu germer sur place, alors que ces germi- 
nations n'ont pas ete observees dans les autres sites des 
marais a sediments non meubles. 



(*)Nomenclature d'apres Abbayes H.des et al.(1970) 

335 



Situation 5) Territoires etrepes. 

Solution la plus extreme de nettoiement puisque la roche- 
mere, ici limons quaternaires decalcifies, est mise a nu. 
A part quelques exceptions tres locales, a la fois le con- 
tingent de graines produites avant 1978, et 1' ensemble de 
la masse vegetale epi - et endogee a ete detruite sur de 
vastes espaces comme par exemple dans l'estuaire de Ker- 
lavos, situe a quelques kilometres a l'Est de l'lle Grande. 
Ailleurs (marais i, 3, 4, 5, 6, 7) c'est essentiellement 
la partie proxiaale des marais qui a ete amputee de la 
sorte. 

Processus en cours : 

Initiation d'une nouvelle pedogenese. 

Le retablissement d'un couvert vegetal ne peut provenir que 
d'une succession primaire obligatoire ef f ectivement enga- 
gee apres une periode de latence de 1 an via 1' installa- 
tion de populations therophytiques essentiellement cons- 
titutes de differentes especes annuelles du genre Salicor- 
nia. 



CARTOGRAPHY CHRONOLQGIQUE D'UN MAPvAIS PRIS COMME EXEMPLE : le MARAIS 

NORD D'AN INIZIGO, 

Les caracteres particuliers de ce marais dont la localisation est 
precisee sur la figure 1, sous le numero 6, et qui nous l'ont fait choi- 
sir comme exemple reside dans la variete des habitats contigiis, parti- 
culierement 1' existence de prairies saumatres supra-littorales dans sa 
partie N, dominees soit par des roselieres a Scirpus tabernaemontani et 
Scirpus maritimus soit par des prairies a Juncus maritimus , espece quasi- 
exclusive sur de grands espaces. 

Morphologiquement, ce marais se releve peripheriquement , le reseau 
hydrographique convergeant en son centre se resoud en deux chenaux ma- 
jeurs orientes Est-Ouest. Sa partie Ouest a ete partiellement etrepee 
tandis que sa partie Sud a fortement ete pietinee, le sous-ensemble Nord 
etant de ce point de vue, peu touche. 

La figure 2 renseigne schematiquement sur la distribution spatiale 
des agressions qu'il a subi en 1978 : absence de pollution, pollution 
sans nettoyage, pollution puis nettoyage, etrepage proximal a l'Ouest. 
La partie Nord-Est a ete remblayee a differents moments depuis 1978. 

Aitisi, les cinq situations: precitees se retrouvent ici, mais les 
trois premieres dominent. 

Les figures 3, 4, 5 se rapportent a. des constats etablis en Aout 
1979, 1980 et 1981. II ne s'agit pas a. proprement parler de cartes de 
vegetation, puisque 1' aspect qualitatif n'est pas le but de ces repre- 
sentations. Celui-ci en effet, est de fixer,, a iin moment donne, l'etat 
de la vegetation d'un double point de vue : 

- progres de la cicatrisation, 

- niveau de reconstitution des communautes vegetales. 



336 



Plus precisiment le codage correspond : 

- Pour le premier groupe (A) a. des peuplements recouvrant la quasi- 
totalite du sol, au moment de la cartographie ; le caractere differentiel 
intergroupe etant celui de la diversite specif ique a ce moment la, 

- Pour le second groupe (B) , il s'agit de peuplements en cours de 
regeneration ou soumis a. succession primaire. La destructuration, la de- 
nudation a pu y avoir ete tres forte et le recouvrement (hormis en niveau 
6 pour les especes annuelles) est toujours inferieur a 50 % de la surface. 

Code des figures 3, 4 et 5 , 

Groupe A : recouvrement des especes perennes pouvant atteindre 100 % 

Niveau 1 : Vegetation plurispecif ique, non touchee par les 
hydrocarbures ou vegetation ayant recouvre, a 
la fois sa diversite originelle, mais aussi sa 
structure anterieure. Dans ce cas on parlera de 
retablissement acheve. 

Niveau 2 : Vegetation paucispecif ique (n inf. a 3 especes). 

Niveau 3 : Vegetation monospecif ique. Ce resultat peut etre 
atteint de deux fa^ons ; la regeneration est le 
fait d'une seule espece ou le fait du retablisse- 
ment complet d'un clone ( cf . roselieres) . 



Groupe B : recouvrement des especes perennes inferieur a 50 % 
te specifique indifferente : 



diversi- 



'/Z$yP%tti Niveau 4 : Recouvrement compris entre 50 et 25 % 
[J] Niveau 5 : Recouvrement compris- entre 25 et 5 % 



Niveau 6 : Recouvrement inferieur a. 5 % pour les especes 
perennes, mais pouvant depasser 80 % en ce qui 
concerne les therophytes. 

Dans ce dernier cas, il s'agit d'un recouvrement 
saisonnier . 

] Niveau 7 : Recouvrement nul aussi bien pour les especes pe- 
rennes que pour les especes annuelles. 

II est ainsi possible, en un lieu donne, de suivre |es cbangements 
de statuts, et de comparer d'un site a 1' autre, 1 'amplitude de ces chan- 
gements et leur vitesse relative, et ceci pour une mime gamme d'habitats 
(cf, ci-apres). 

La figure 6, quant a elle, est. plus syntbetique puisqu'elle indique 
les ecarts des etats constates en Aout 1981 par rapport a. ceux d'Aout 
1979. 



337 



Code de la figure 6 



Pas de changement 

[.-.•. •. -, -~| Passage du niveau 7 au niveau 6 ( i. e. acquisition d'un cou- 
vert phanerogamique saisonnier a. therophytes) . 




Changement d'etat correspondant a 1 niveau 

[] Changement d'etat correspondant a 2 niveaux 

Changement d'etat correspondant a 3 niveaux 
et ce, jusqu'a la categorie 4 incluse. 

Passage d'un niveau inferieur a 3 a. un niveau 3, 2 ou 1 

] Passage du niveau 3 au niveau 2, de celui-ci au niveau 1 

1 1| | j | |p Passage du niveau 3 au niveau 1 

cas particuliers : 

BjBi||||| | Evolution regressive, mais qui peut correspondre a des 
gains spatiaux d'une espece sociale, au detriment d'un 



une 



vegetation non concurrentielle. 



/££'' ] Secteurs plantes (zone de restauration de l'equipe "ameri- 
caine" Pr. Seneca-Raleigh). 



338 




\ 




y 




I 




•• 
< 




7 
1 



Figure 2. Marais 6 -Extension de la pollution et modal it es 
'de nettoiement • 

339 




Figure 3. Marais 6-Etat en 1979 (legende dans le texte) 



340 




Figure 4. Marais 6-Etat en 1930 (legende dans le texte) 

341 




Figure 5. Marais 6-Etat en 1981 (legende dans le texte) 



342 



:§§§' 




Figure 6. Marais 6- Distribution spatiale des ecarts de niveaux 
observes entre 1979 et 19*1 .d s gende dans le texte) . 

343 



Commentaires 

Mis a. part un petit nombre de points depourvus de toute vegetation, 
y compris therophytique, tous les autres ont vu leur couvert vegetal, 
meme fragmentaire, evoluer avec le temps. Ces transformations sont, dans 
la plupart des cas et selon nos conventions, progressives - i.. e.. tendent 
vers une cicatrisation des espaces denudes. Celle-ci peut etre accompa- 
gnee par une augmentation de la diversite specif ique, lorsqu'il y a eu 
destruction selective d'une partie du contingent specifique de depart, 
mais non denudation extensive. Cependant des tendances regressives s'ob- 
servent plus localement. 

II existe une certaine opposition entre les parties Nord et Sud du 
marais (gauche et droite sur les figures 2 a 6) , de part et d'autre des 
deux chenaux majeurs medians. L'etat de la vegetation, en secteur Sud, 
ne depasse pas le stade peuplement therophytique, ce qui correspond, 
43 mois apres le depot de petrole, a. la destruction effective presque 
totale des especes perennes dans - ces zones bordieres. 

On constate neanmoins (cf .figure 6) que la cicatrisation a partir 
de regenerations autochtones est comparativement assez rapide le long 
de la route bordant An Inizigo au Nord. En trois ans, l'amplitude du 
changement est de l'ordre de deux ou trois niveaux, Une cause possible 
de cette regeneration plus rapide, qui interesse surtout les hemicryp- 
tophytes a souche et les chamaephytes ligneuses mais aussi les hemicryp- 
tophytes stolonif eres telles Puccinellia maritima , est a. rechercher 
dans le ruissellement permanent ou la percolation laterale de sources 
provenant de l'ile. C'est ef f ectivement en tete des chenaux et sur les 
marges que ce processus est le plus rapide. 

Lorsque l'on compare les figures 2 et 6, on remarque que ce sont 
les zones pietinees qui presentent le plus faible taux de reprises, 
exprime par le progres, en recouvrement , des especes vivaces. II faut 
noter toutefois que la vegetation initiale, dans la haute slikke, le 
bas-schorre et le schorre moyen etait pauci - ou monospecif ique. Le 
pietinement, ajoute a l'effet immediat du petrole sur des plantes a 
appareil vegetatif essentiellement epige a des effets drastiques et 
surtout durables. Ainsi ces deux facteurs, l'un initial, 1 'autre conse- 
cutif, mais encore operant actuellement , constituent-ils, en premiere 
hypothese, la raison majeure du retard dans le retablissement d'une 
vegetation, du fait de leurs effets multiplies, directs ou indirects. 

L' exposition aux effets dynamiques de la maree joue egalement, 
aussi bien sur le plan de la reprise que celui de 1' installation d'in- 
dividus nouveaux dans les espaces tres denudes. L'exposition favorise, 
etant donne l'absence de couverture vegetale, l'erosion des berges, ce 
qui conduit a des ef fondrements locaux qui, a terrae, peuvent entrainer 
des modifications dans les drainages, par occultation des chenaux les 
plus etroits ou les moins. profonds. Mais cette exposition, comme nous 
1 avons dit plus haut, a pour consequence une destruction acceleree de 
la couche coherente de petrole deposee sur les sediments, meme lorsque 
celle-ci a ete tassee. Des souches survivantes ainsi liberties ont pu 
alors reprendre leur developpement , par formation de nouvelles pousses 
aeriennes. a partir de bourgeons adventifs. 

Par contre, en ce qui concerne la colonisation de ces espaces, 
l'exposition aux effets directs de la mer joue comme un facteur concrai- 

344 



re. II n'en est pour preuve que 1' installation reussie, dans des situa- 
tions mesologiques homologues, des especes annuelles, en l'absence de 
ce facteur (i. e. dans les zones abritees, en position plus interne). 



sons 



La partie Nord du marais se differencie des autres pour deux rai- 

- sa physiographie, 

- la nature de sa couverture vegetale. 

La topographie et 1' existence de nombreuses sources qui ont assure 
un auto-nettoyage precoce du petrole depose dans ces secteurs distaux 
font que le degre de destruction et de destructuration du couvert vege- 
tal y a ete comparativement plus faible. Structuralement en effet, les 
geophytes a rbizomes dominent et les parties aeriennes, qui de toutes 
fagons, ont une duree de vie limitee, ont joue le role de piege a. petro- 
le, sans que les organes endoges de perennance n'aient ete immediatement 
atteints. Seule, la sous-strate des peuplements, composee d'heraicrypto- 
phytes stolonif eres, a ete endommagee, mais la reconstitution de ce ta- 
pis inter stitiel est en cours et meme localement, dans les zones de 
stagnation des eaux continentales, presque achevee, 

ri ressort de ces observations que dans un meme marais les condi- 
tions et les modalites de retablissement de la vegetation sont tres va- 
rices. Si la regeneration, a proprement parler, est engagee, a des de- 
gres divers et pour des raisons et avec des moyens divers, 1' installa- 
tion de nouveaux individus, par colonisation directe ne s'observe pas, 
hormis le cas des especes annuelles dans les lieux proteges. Aussi peut- 
on dire que le retablissement est assure par le developpement vegetatif 
des seuls individus ou clones survivants, sans qu'il y ait ajout quan- 
titatif ulterieur signif icatif . 

Les evolutions ulterieures sont cependant dans la majorite des cas 
conditionnelles et dependantes de la resistance des populations regene- 
rees a la pollution remanente diffuse ou directe, de la. les delais va- 
riables observes dans 1' initiation du processus ! ( cf . figure 6). 



ANALYSE DIACHRONIQUE DE QUELQUES TRANSECTS PERMANENTS. 

Parmi les transects etablis en 1979 et regulierement suivis depuis, 
nous en avons selectionne trois, deux dans les marais de l'lle Grande, 
le dernier dans l'estuaire de Kerlavos, La localisation des deux premiers 
est indiquee sur la figure 1. 

- A Kerlavos, il s'agit d'un schorre moyen a. Armeria maritima et Plan— 
tago maritlma , etrepe par decapage des dix premiers centimetres du sol. 
Le substrat plan est const itue de limon. Le mode d' exposition est abri- 
te. En utilisant le code des figures 3 a 5, le niveau de depart, en 1979 
est 7. 

- Marais 5-Est d'An Inizigo. Transect d'orientation ENE-WSW, etabli 
dans une zone exposee en partie aux actions dynamiques de la maree et 
qui fut a la fois tres polluee, tres pietinee et soumise egalement au 
passage d'engins. Deux petits chenaux recoupent ce transect qui se rele— 
ve legerement vers 1'Est. Selon les sections de celuivci, les niveaux de 
depart sont de 4 ou 5. _,,. 



- Marais 3. Ce transect, situe en mode tres abrite, est oriente NW- 
SE. Son point de depart haut est situe sur une levee artificielle non 
touchee par le petrole, mais tres pietinee. II se tennine dans une zone 
marecageuse occupee par une prairie a. Juncus maritimus , encore actuelle- 
ment tres polluee, mais non pietinee. Les niveaux de depart vont de 1 
a 4. 

Ces transects illustrent ainsi les differents cas de figures ren- 
contres, que ce soit sur le plan de la vegetation, des habitats, des 
destructions. 



Legendes des figures 7A - 7B, 8A-8B , 8C, 9 A - 9B . 

Figures 7A, 8A, 9A. Les transects sont constitues de carres contigils de 
0,50 x 0,50 m subdivises chacun en 25 cases de 0,10 x 0,10 m, Les 
presences specif iques sont relevees dans chacune des cases. L'e— 
chelle des hauteurs, dans le diagramme est etahlie comme ci-apres : 

, ,^15-2(^^5 
1< l-sS^ioJg^i ^ 



Presence de l'espece dans n cases 

Afin de faciliter la comparaison des distributions lineaires et des 
recouvrements sur la ligne, les donnees relatives a chaque annee, 
pour une espece donnee, sont rapprochees. 

L'ordre de presentation des especes, dans les diagrammes est con- 
ventionnel. II s'appuie sur les types suivants : 

- plante a. organe de resistance endoge. rgeophyte a. rhizome 

*- hemicryptophyte a souche 

- plante sans organe de resistance en- p chamaephyte ligneuse 

doge L hemicryptophyte stolonifere 

- therophytes (y compris especes biannuelles) 



Figures 7B, 8B, 9B : sont indiques: 

- le nombre de cases par carre occupees par la vegetation, toutes 
especes confondues. 

- le nombre d' especes presentes dans chaque carre. 



Figure 8C : Pour ce qui est du transect 5, nous avons presente differem- 
ment les donnees, par la distinction des especes annuelles et pe- 
rennes et leur importance, exprimee comme la somme des cases occu- 
pees par chacune des especes. Ces sommes sont ensuite cumulees, de 
la les depassements possibles dans le cas de cooccurence ou meme de 
debut de stratification. La somme des recouvrements individuels 
peut ainsi etre superieure aux 100 % d'un carre elementaire. 




346 



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Figure 7. Transect permanent -Estuaire de T'erlavos. 
A-Distribution spatiale des especes 
P- T 'ariation longitudinale du recouvrenent et de la diversite. 



347 



TRANSECT 'VVATS 5 




Figure 8. Transect permanent -Marais 5 (cf .figure 1) 
A-Distribution spatiale des espaces. 

348 






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Figure 8. Transect permanent-Marais 5 -"-Variation longitudinale 
du recouvrement et de la diversite 

349 



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du recouvrement des plantes annuelles et vivaces (cf . texte) . 

350 



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du recouvrement des plantes annuelles et vivaces (cf .texte) 



351 




'igure 9 



Transect permanent-Marais 3 (cf .figure 1) 
A-nistribution spatiale des especes 

352 



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B-Variation longitudinale du recouvrement et de la diversite 

353 



Commentaires 

- Estuaire de Kerlavos (figures 7A, 7B) 

Les especes vivaces ont un recouvrement presque nul en 1979, tandis 
que s'installent quelques pieds de Salicornia ramosiss^a et Salicornia 
gr. herbacea (non distinguees sur les transects !). 

Le fait remarquable est la rapidite avec laquelle, en moins de trois 
ans, les therophytes ont sature lespace disponible, ce peuplement saison- 
nier ayant un recouvrement qui peut atteindre 100 %. II s'agit d'une co- 
lonisation primaire active (stade I - especes "opportunistes" dites a. 
strategie "r"). II faut noter 1' Importance des centres de dispersion ini- 
tiaux (cf .Brereton, 1971). Les pieds-meres etablis en 1979 ont produit 
des graines qui n'ont pas ete exportees etant donne le niveau topogra- 
phique des lieux et leurs positions tres internes dans 1' estuaire. II y 
a ainsi capitalisation locale des graines qui germent pratiquement sur 
place. La presence saisonniere d'un revetement algal micropnytique exer- 
ce une influence aussi Men dans le piegeage des graines deposees sur 
le sol que sur leur germination, au printemps suivant (protection ther- 
mique, hydrlque, photique, mais aussi protection contre les agents dyna- 
miques) . 



- Marais 5 (E-An Inizigo) (figures 8A, 8B et 8C) 

Augmentation, entre 1979 et 1981 de la richesse specif ique dans 
certaines sections du transect, notamment celles correspondant au schor- 
re moyen. Cette augmentation vient de reprises relativement tardives 
d'hemicryptophytes a souche et rosette telles Plantago maritima , Limo- 
nium vulgare et Armeria maritima dont 1' importance numerique reste nean- 
moins tres faible. De nouvelles therophytes apparaissent en 1981 : Coch - 
lear ia anglica et Parapholis strigosa . 

En ce qui concerne les plantes perennes, et si l'on met a part 
Juncus maritimus , il y a gain dans le recouvrement de chaque population. 
Le phenomene interessant est celui du decalage progressif des optimums, 
d'une annee sur l'autre, ce qui peut traduixe deux faits : 

. 1' importance de la competition interspecif ique, du fait de la 
mise en contiguite de clones regeneres, et qui se sont ensuite develop- 
pes lateralement d'une fagon centrifuge. 

. la biologie de la regeneration qui favorise un developpement 
plus actif des parties du clone les moins endommagees. Si cette partie 
est en situation marginale, par rapport au clone ancien, il peut y avoir 
double mouvement, normalement vers l'exterieur, mats aussi vers l'inte- 
rieur (developpement centripete) assurant ainsi une reconquete des posi- 
tions anterieures. 

Un clone epargne, a. developpement plagiotropique dominant, se cica- 
trise lui-meme tout en gagnant des espaces, a sa peripherie, qu'il n'oc- 
cupait pas precedemment du fait de l'occupation des lieux par d'autres 
especes ou par des clones de la meme espece (on peut rattacher ce pheno- 
mene a celui du "die-back" observe chez les especes a extension vegetati- 
ve). 

C'est ainsi que ce processus peut conduire a des redistributions 
spatiales de dominance, apres perturbation, telles celles signalees par 
Baier (1973). 354 



De ce point de vue, des especes stolonif eres ou radicantes comme 
Puccinellia maritima et Halimione portulacoides ont un developpement 
spatial qui s'accelere avec le temps et qui est rapide compte-tenu du 
nombre de pieds survivants au depart. Comme dans la section du transect 
ou ces deux especes se developpent, le terrain est plan, done la pente, 
via les durees et frequences de submersion n'est pas un facteur limitant, 
l'aire actuelle de ces plantes tend a rejoindre leur aire potentielle , 
en 1' absence de concurrence. 

L' occupation de l'espace par les annuelles montre la meme tendance 
qu'a Kerlavos. Ilya saturation des espaces interstitiels . Le meme pro- 
cessus de capitalisation a partir des pieds-meres s'observe encore ici. 
De plus, apparalt un phenomene de nucleation (Yarranton et Morrisson, 
1974). En effet, toute vegetation dans un espace intertidal soumis a 
submersion est un obstacle pour les particules sedimentaires-et les se- 
mences-vehiculees par l'eau. Dans un second temps, ces semences qui peu- 
vent provenir de plantes perennes egalement, germent dans le lieu ou 
elles se sont deposees a la f aveurdetet dans les sediments meubles depo- 
ses a la base de l'obstacle. On observe de la sorte,dans les secteurs ou 
ce phenomene se produit, a la fois une acceleration autoentretenue de la 
sedimentationjet, d'une fagon concomittante, une acceleration de la colo- 
nisation accompagnee d'une augmentation de la diversite specifique loca- 
le. Cette phase d' augmentation transitoire de la diversite est bien con- 
nue : transitoire car elle est suivie ( cf. marais 2, remblai artificiel, 
non etudie dans cette communication) par une legere decroissance de la 
richesse specifique, consequence du comportement "imperialiste" de cer- 
taines especes "couvre-sol" . 

L'observation de la figure 8B montre, a un autre niveau le phenome- 
ne deja decrit a Kerlavos de saturation du plan -toutes especes confon- 
dues - egalement 1' augmentation de la diversite dans certaines sections, 
en meme temps que la variation horizontale de celle-ci, entre 1979 et 
1981, traduisant l'heterogeneite, a grande echelle d'un tel espace. 
L'explication est plus a rechercher du cote de la competition interspeci- 
fique que de celui de contraintes mesologiques (types biomorphologiques 
compatibles ou incompatibles, cf . discussion in Levasseur et al. , I.e. ) . 

La figure 8C montre la part prise, des 1980, par les therophytes, 
part croissant tres brutalement en 1981. Mais 1 'acceleration la plus 
forte se tient precisement la ou une vegetation vivace deja installee 
fait protection alors que dans la partie gauche du transect, plus expo- 
see, la regeneration d' especes vivaces est moins active ou la des- 
truction initiale de celles-ci plus complete 'les annuelles sont nume- 
riquement moins abondantes. 



- Marais 3 dit de Notenno (figures 9A, et 9B) 

Ce transect est d'une interpretation plus delicate que les precedents 
etant donne l'heterogeneite des situations presentes et les tendan- 
ces en quelque sorte inverses qui s'y developpent depuis 1980. 

Ce qui frappe a premiere vue dans la figure 9A est le desequilibre 
entre les parties gauche et droite du diagramme pour ce qui est de la 
diversite specifique en chaque point. Deux raisons peuvent etre evoquees : 



355 



1 - appel a la notion de composition floristique initiale ( cf . 
Egler, 1954), fonction, dans ce cas particulier, de gradients mesologi- 
ques le long de cette toposequence induisant en particulier une riches- 
se specif ique maximale dans la partie moyenne du gradient topographi- 
que, mais avec cooccurence des limites basses. 

2 - 1' opposition peut aussi etre interpretee comme le resultat des 
perturbations dif f erenciees qui se sont exercees et qui continuent de 
s'exercer dans ces lieux, notamment dans les parties deprimees du tran- 
sect et qui marquentl' influence effective de l'epandage du petrole, et 
ce jusqu'a la limite superieure de depot. On notera a ce propos que la 
cicatrisation a ete rapidement effective au dessus de cette limite et 
ceci des 1980, alors que le recouvrement vegetal reste discontinu en 
dessous ( cf . figure 9B). 

Le fait a retenir reste cependant le remplacement de la population 
primitive a Juncus maritimus , seule espece rescapee en 1978 par une es- 
pece de type biomorphologique different, Halimione portulacoides -cha- 
maephyte ligneuse a tiges radicantes- qui etend son aire, dans les par- 
ties basses, depuis 1980. Dans l'espace disponible libere, au moins 
au niveau et au dessus du sol, le meme phenomene de colonisation en nap- 
pe par les annuelles s' observe, de la part de Salicornia du groupe her- 
bacea , tandis que les autres therophytes -y compris des formes annuelles 
d' Aster tripolium - s' installent , a leur niveau bionomique habituel sur les 
parties moyennes et hautes du transect. 

L' evolution des performances de Juncus maritimus , geophyte a rhi- 
zome est interessante car tres representative de la tendance generale 
au declin qui affecte, en divers lieux, et ce depuis 1980, des populations 
entieres de cette espece. Celle-ci, rappelons-le, est une des plantes 
qui occupait et qui occupe encore la plus grande partie des marais 3, 
4, 5 et 6 et qui a ete consideree par nous en 1979 comme une plante re- 
sistante . Comme son role physionomique, structural et coenotique est con- 
siderable, toutes modifications dans sa distribution et son abondance 
spatiale pourront avoir, a plus long terme, des incidences certaines. 

Les donnees quantitatives suivantes (figures 10 et 11) illustrent 
de telles tendances regressives. La figure 10 presente 1' evolution sai- 
sonniere du rapport biomasse epigee sur necromasse aerienne exprimees 
en poids sec. Les donnees de base sont le resultat de fauches effectuees 
au ras du sol, dans trois quadrats de 0,50 x 0,50 m, pris au hasard a 
trois niveaux topographiques, les recoltes etant ensuite sechees 48 
heures a 65°C On notera 1' inversion du rapport a partir de la fin de 
l'annee 1980 et a terme, ceci conduira a la disparition de l'espece dans 
ce lieu. 

D'une fa^on concomittante, les capacites de reproduction sont alte- 
rees et se traduisent, selon les cas, par une reduction du nombre de ti- 
ges fertiles, ^par des malformations de 1 ? inflorescence et, pour c es der- 
nieres $ p ar une diminution du nombre de rameaux floriferes, par 
1' absence d'etamines ou la non-formation de capsules et de graines ou 
seulement par la production d'un petit nombre de graines avortees. Dans 
le meme temps, les pieces du perianthe peuvent revetir un aspect brac- 
tiforme (cf. figure 12). 

De plus, 1' observation de coupes transversales de rhizomes montre 
une necrose des parenchymes; ceci, ajoute a un dessechement des apex 
vegetatifs, pose le probleme de la nutrition hydrique et minerale de 

(*) cjf.figure 11. 356 



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Figure 12. T'orphologie comparee d' inflorescences de Juncus maritimus Lam, 
provenant d'un meme clone situe au S du marais A (cf. figu- 
re 1) prelevees en Aout 1079 et Aout 1981. 



359 



ces organes, done des effets a long terme du petrole, toujours present, 
sur la physiologie et sur certains metabolismes de la plante. Apparem- 
ment, il n'y a pas renouvellement des reserves dans le rhizome : celles 
subsistant apres 1978 ont maintenant ete consommees. II faut rappeler 
a ce propos les conclusions de Baker ( l.c . ) relatives a la sensibilite 
de cette espece a des pollutions chroniques par les hydrocarbures. 

L'observation simultanee des deux courbes montre la realite d'une 
tendance exprimee de deux facons differentes et qui ne touche pas seu- 
lement l'appareil reproducteur ! Rappelons cependant qu'une "allocation 
d'energie" plus forte en faveur de l'appareil vegetatif est consideree 
comme classique par Ranwell (1972) chez les plantes des marais mari- 
times. La veritable question relative a la nature et aux delais de reta- 
blissement de la vegetation, dans les marais de l'lle Grande, est la. II 
est vraisemblable que ce retablissement aura lieu, naturellement mais 
aussi avec l'aide des plantations volontaires; mais, sur de grands espa- 
ces encore occupes par le Jonc, il aura lieu sans lui, ce qui pourra mo- 
difier passablement le paysage vegetal, mais aussi les strategies de res- 
tauration, celle-ci ne pouvant alors etre uniquement focalisee sur les 
seuls secteurs actuellement denudes. 



CONCLUSIONS 



Les quelques exemples presentes montrent qu'au dela de la variete 
constatee, un processus de retablissement du couvert vegetal est effec- 
tif en de nombreux lieuxj les gains en recouvrement, par rapport a la 
situation de 1978, representent environ 35 %. II est vraisemblable que 
localement on assistera a une acceleration du phenomene puisque par nu- 
cleations en chaine, le nombre de points d'agglutination des sediments 
et des sentences va croltre d'une fagon non lineaire. 

II reste encore des sites ou la destruction de la vegetation a ete 
totale. Pour differentes raisons ils demeurent steriles, en ce sens que 
des germinations ne peuvent s'y effectuer. Aussi un retablissement natu- 
rel y est-il peu probable au mo ins dans un avenir proche. II semble 
alors que des restaurations au moyen de plantations soient la seule voie 
realiste possible, comme en temoignent les succes enregistres, a la sui- 
te des deux annees d' experimentations menees dans ces secteurs par le 
Dr. Seneca et son equipe. En effet, 1' introduction de boutures, selon 
les cas, avec ou sans sol, leur reprise et leur developpement ulterieur, 
montre a contrario que e'est la phase "germination" qui est inhibee et 
done qu'en la court-circuitant, on accelere la cicatrisation. De la meme 
maniere, comme ces boutures font obstacle, d'autres especes peuvent alors 
s'implanter naturellement, mais dans un second temps, dans ces lieux, 
retablissant une diversite specif ique qui n'existait pas au depart lors 
de 1' experience. Notons qu'un phenomene similaire peut etre initie par 
les nappes de therophytes qui marquent frequemment la premiere phase de 
la recolonisation. 

Si l'on compare l'etat actuel de la vegetation avec l'etat primitif, 
on constate que le retablissement de celle-ci passe en de nombreux lieux 
par une redistribution spatiale des especes, au profit d'un petit nombre 
d'entre elles. Cette redistribution, qui peut quelquefois aller jusqu'a 
la monopolisation (transitoire ?) d'un espace peut avoir deux causes : 

360 



- les plantes survivantes -initialement "resistantes" ne possedent 
pas des capacites d' extension vegetative suffisantes pour cicatriser 
les espaces interstitiels denudes, alors que d'autres especes, "sensi- 
bles" celles-la aux premieres perturbations presentent ces qualites,de 
part leur organisation et leur ethologie; de la l'ecart actuellement 
observe entre la composition floristique initiale du site et la compo- 
sition du moment. 

- des especes tout-a-fait resistantes, telles Juncus maritimus et 
dans une moindre mesure, Tri^lochin maritima , deviennent sensi- 
bles a la pollution chronique qui affecte maintenant ces marais. LeurS 
populations, en declin, sont envahies peripheriquement par des especes 
autrefois cantonnees, du fait de la saturation de l'espace par les pre- 
mieres , en dehors des clones les plus denses. Ce sont d'ailleurs les 
mimes especes qui jouent ce role dans les deux cas, a savoir Puccinellia 
maritima et Halimione portulacoides , toutes deux capables, par stolons 

ou tiges radicantesj de couvrir le sol, meme lorsque celui-ci est encom- 
bre, a un niveau endoge,par des souches ou des rhizomes qui se maintien- 
nent longtemps apres la mort de la plante. 

La resistance d'une plante est done une notion tres relative, elle 
est en quelque sorte individuelle et thematique mais 1' organisation fu- 
ture d'un couvert vegetal apres perturbation doit autant aux plantes 
dites resilientes qu'a des especes "resistantes" en nombre insuffi- 
sant ou devenant sensiblesa d'autres causes que celles qui avaient au- 
torise la resistance de depart. 

La soi-disant robustesse d'un tel ecosysteme tient plus a ses ca- 
pacites de cicatrisation via des colonisations peripheriques ou implan- 
tations directes, lorsqu'elles sont possibles, qu'a la resistance alea- 
toire, a plus long terme, d'autres especes. Mais encore y a-t-il une 
nuance fondamentale entre la reaction vis-a-vis d'une perturbation 
except ionnelle, mais finie dans le temps et une perturbation qui devient 
chronique et qui n'a pas ete integree dans le passe par exemple au moyen 
d'une selection particuliere d'especes. C'est peut-etre ce qui est en 
train de se dessiner actuellement. 

Encore faudrait-il a^iner le concept d' ecosysteme littoral. II 
ae p-Tusijeurs r i , . , 
vaut mieux en effet parler ecosystemes superposes ou inclus dont les 

caracteres qualitatifs, structuraux et dynamiques sont differents au 
travers des types biomorphologiques representes, de leur abondance rela- 
tive, de leur distribution spatiale. Une meme perturbation s'exercera 
alors d'une fagon selective et differenciee sur les elements composant 
une vegetation locale, dela les delais et les modalites differentes du 
retablissement consecutif. Celui-ci pourra meme ne pas etre possible : 
une Spartinaie alteree ne pourra etre reconstitute que par la Spartine 
elle-meme. 

Plus fondamentalement , la nature, 1' abondance relative, la dis- 
tribution spatiale des especes presentes ou apparaissant pendant la 
succession pourront etre soumis a variation, changeant dans un premier 
temps la composition mais aussi la structure des peuplements en cours 
de retablissement, ceci a l'interieur de certaines limites imposees 
par l'environnement mesologique. Ces ecarts et ces divergences, par rap- 
port a l'etat ancien, ne constituent pas des phenomenes "anormaux" et/ 
ou eventuellement inquietants. lis representent seulement la materiali- 
sation instantanee du processus fondamental qui conduit a une saturation 
par la vegetation de l'espace disponible, lorsque l'opportunite s'y pre- 
te, comme c'est le cas en ce moment. 

361 



REFERENCES 



Abbayes, H. des, G. Claustres, R. Corillion et P. Dupont, 1971, Flore 
et vegetation du Massif armoricain. I. Flore vasculaire, P.U.B. 
St-Brieuc, 1226 pp. 

Baker, J.M. , 1973, Reco very of salt marsh vegetation from successive 
oil spillages : Environ. Pollut., vol. 4, pp. 223-230. 

Baker, J.M., 1979, Responses of salt marsh vegetation to oil spills 

and refinery eff luents:_in Jefferies R.L. and A.J. Davy (eds.), 
Ecological processes in coastal environments, Blackwell Scien- 
tific Publ., Oxford, 684 pp. 

Brereton, A. J., 1971, The structure of the species populations in the 

initial stages of salt-marsh succession : J. Ecol., Vol. 59, pp. 
321-338. 

Egler, F.E., 1954, Vegetation science concepts : I. Initial floristic 
composition, a factor in old field vegetation development : Ve- 
getatio ., vol. 4, pp. 412-417. 

Levasseur, J., M.-A. Durand et M.-L. Jory, 1981, Aspects biomorphologi- 
ques et floristiques de la reconstitution d'un couvert vegetal 
phanerogamique doublement altere par les hydrocarbures et les 
operations subsequentes de nettoiement (cas particulier des ma- 
rais maritimes de l'lle Grande, Cotes du Nord) : in AMOCO-CADIZ, 
Consequences d'une pollution accidentelle par les hydrocarbures, 
C.N.E.X.O., Paris, 881 pp. 

Ranwell, D.S., 1972, Ecology of salt marshes and sand dunes, Chapman 
and Hall, London, 258 pp. 

Yarranton, G.A. and R.G. Morrisson, 1974, Spatial dynamics of a prima- 
ry succession : Nucleation : J. Ecol., Vol. 62, pp. 417-428. 



362 



RESTORATION OF MARSH VEGETATION IMPACTED BY THE AMOCO CADIZ OIL 
SPILL AND SUBSEQUENT CLEANUP OPERATIONS AT ILE GRANDE, FRANCE 

Ernest D. Seneca and Stephen W. Broome' 

INTRODUCTION 



General 

Tidal salt marshes functon to stabilize estuarine shorelines, to 
exchange nutrients with sediments and the surrounding waters, to 
provide energy as detrital material to the estuarine food web, and to 
serve as nursery grounds for many commercially important fish and 
shellfish. Because competing land uses have resulted in a decrease in 
areal extent of these valuable resources in the past, there have been 
concerted efforts recently to preserve the remaining marshlands and to 
reestablish marshes at selected sites. Techniques and procedures have 
been developed to: (1) reestablish marsh in areas where Man has 
destroyed natural marsh, (2) reestablish marsh along shorelines where 
storms have damaged or destroyed natural marsh, (3) establish marsh 
along canal banks and shorelines to stabilize the substrate and retard 
erosion, and (4) establish marsh on dredged material (Woodhouse et al., 
1974; Garbisch et al., 1975; Seneca et al., 1976). 

Our research efforts in marsh establishment along the southeastern 
coast of the United States led us to respond to an invitation from the 
joint scientific commission of the National Oceanic and Atmospheric 
Administration (NOAA)/Centre National pour l'Exploration des Oceans to 
study the effects of the Amoco Cadiz oil spill. We developed a 
proposal for restoring marsh at the lie Grande site adapting techniques 
and procedures developed for Spartina alternif lora Loisel. in North 
Carolina (Woodhouse et al . , 1974; Seneca et al., 1976) to restoration 
of a part of the lie Grande marsh using vegetation indigenous to that 
region. This interim report contains results from 2 years' marsh 
rehabilitation research at lie Grande and a nearby estuary at Kerlavos. 



Literature Review 

The effects of oil pollution on salt marsh vegetation have been 
studied and reported by European researchers. Based on observations of 
Welsh salt marshes affected by oil spills from the Chryssi P. 
Goulandris in January 1967 and the Torrey Canyon in March 1967, Cowell 
(1969) rated susceptibility of marsh plants to crude oil and concluded 
that salt marshes dominated by Spartina townsendii H. and J. Groves and 
Puccinellia maritima (Huds.) Pari, were most subject to damage. 
Stebbings (1970) studied the effects of oil from the Torrey Canyon 
spill on salt marshes in Brittany and found that these marshes were 

1 ) Department of Botany and Department of Soil Science, respectively 
North Carolina State University, Raleigh, North Carolina U.S.A. 27650 

363 



able to withstand 2 to 10 cm of oil with only slight, short-term, 
floral composition changes. Apparently, most of the toxic fractions 
had been lost from the Torrey Canyon oil, since it had been weathered 
at sea for 2 to 18 days. Stebbings noted that oil appeared to form an 
impervious layer on the substrate preventing gaseous interchange 
between soil and air, causing reducing conditions in the mud, and 
ultimately chlorotic symptoms in plants. Stands of Agropyron pungens 
(Pers. ) R. and S. , Festuca rubra L. , Juncus maritimus Lam., and 
Scirpus maritimus L. were extremely vigorous and seemed to derive some 
nutritional benefit from the breakdown products of this Torrey Canyon 
oil. Cowell and Baker (1969) noted that populations of annuals such as 
Suaeda maritima (L. ) Dum. and Salicornia spp. near Pembroke, Southwest 
Wales, were reduced initially but were recovering a year after oiling 
from the Chryssi P. Goulandris. Halimione portulacoides (L.) Aell. was 
the plant most badly damaged. In June 1968 the plant species with the 
greatest coverage in the upper, middle, and lower marsh ( Festuca rubra , 
Puccinellia maritima , and Spartina townsendii , respectively) had 
recovered completely (Cowell and Baker, 1969). Baker (1971a-i) 
reported on several aspects of the effects of oil pollution on salt 
marsh and concluded that single oil spillages do not cause long-term 
damage to marsh vegetation (Baker, 1971a). 

These studies indicate that marsh vegetation is resilient and 
often can recover from single oil spills. Baker (1971e) suggests that 
it is best to let an oiled marsh recover naturally. However, 
persistent oil pollution has killed Spartina marsh at Southampton Water 
(Ranwell, 1968). Such sites may develop extremely anaerobic conditions 
in the mud so that higher plants can no longer grow on them. Cowell 
(1969) states that repeated contamination is likely to have 
increasingly serious effects if anaerobic conditions are created due to 
bacterial use of oxygen in the biological oxidation of the oil. We 
found no account of marsh recovery after removal of the upper layer of 
marsh substrate and vegetation. 



Study Sites 

The lie Grande site is a relatively protected estuary with a mean 
tide range of ca . 6 m, a spring tide range of ca. 8 m, and a mean tide 
level of ca. 5 m. Our first visit to lie Grande was in December 1978. 
Our NOAA liason representative, Douglas Wolfe, indicated that the marsh 
west of the bridge at lie Grande was to be our primary study site (Fig. 
1 ) . There were extensive stands of Juncus maritimus on both sides of 
the estuary with lesser stands composed of a mixture of species 
including Puccinellia maritima , Triglochin maritima L., Limonium 
vulgare Mill., Spartina maritima (Curtis) Fern., and Halimione 
portulacoides . There were vast areas with no vegetation cover, the 
result of cleanup operations by the French military to rid the marsh 
of Amoco Cadiz oil. In many areas only the aboveground marsh 
vegetation and associated oil had been removed and in other areas the 
entire marsh surface including the root mat had been removed to a depth 
of over 30 cm. The intertidal creek banks were almost completely 
lacking in vegetation cover. A limited number of substrate samples 
from the disturbed sites were taken which subsequently indicated a 

364 




FIGURE 1. Marsh west of the bridge at lie Grande. Area without 
vegetation is due to removal of oil and vegetation during 
Amoco Cadiz cleanup operations. 



material which was sandy loam in texture and low in nitrogen and 
phosphorus. 

Marsh vegetation adjacent to the disturbed sites indicated that 
prior to the oil spill the natural marsh was composed primarily of 
Juncus maritimus , Puccinellia maritima , Triglochin maritima, Limonium 
yulgare, with lesser amounts of Spartina maritima . Halimione 
portulacoides was dominant along the creek banks. We noted 
considerable variation in the relative dominance of these species and 
others within marshes in the vicinity. Spartina anglica C E. Hubbard 
was present only at a single site at lie Grande as a small clump less 
than 3 m in diameter. This species is abundant in the Bay of Mt. St. 
Michel some 125 km to the east of lie Grande. 



Juncus stands generally occupied the highest elevations of the 
marsh relative to the other species mentioned. Subsequent observations 
indicated that the Juncus marsh is flooded for about 3 days each spring 
tide cycle. Above the level of Juncus there was in some areas a narrow 
fringe of Festuca rubra and Agropyron pungens with associated species. 
Many salt marsh ecologists consider this vegetation to be a part of the 
marsh. This higher zone of vegetation which extends up to ca. 1m 
above the Juncus marsh is flooded relatively infrequently on extremely 
high storm tides and spring tides. It lies above the marsh impacted by 
Amoco Cadiz oil and cleanup operations. Our marsh rehabilitation 
efforts were confined to elevations from 0.8 m below to 0.3 m above 
that of the Juncus marsh. 

365 



Because we wanted to compare the marsh at lie Grande with other 
marshes in the vicinity, we also visited the marsh in the estuary at 
Kerlavos ca . 5 km from lie Grande (Fig. 2). This marsh contained less 
Juncus , no Spartina , and was dominated by Puccinellia maritima, 
Armeria maritima (Mill.) Willd. , and Triglochin maritima along with 
Plantago maritima L. , Cochleria officinalis L. , Halimione portulacoides 
and Aster tripolium L. There was evidence of marsh removal by cleanup 
operations in the Kerlavos marsh also, but it appeared that the marsh 
was much less heavily impacted than that at lie Grande. We chose to 
use this marsh area as a supplemental study site. 




FIGURE 2. Marsh in estuary at Kerlavos. Areas without 
vegetation represent sites of marsh removal during 
Amoco Cadiz oil cleanup operations. 



PROCEDURE 



Substrate 

Substrate samples were taken at the transplant source sites for 
each species and also at the experimental planting sites each year. 
These samples were analyzed for elemental concentrations, pH, organic 
matter, and volume weight by the North Carolina Department of 
Agriculture Soil Testing Division using their routine methods. 



366 



1979 Plantings 

Based on our preliminary plantings made in December 1978 and the 
nutrient analysis of initial substrate samples, we established 9 
experimental plantings in May 1979, using primarily Puccinellia 
maritima (Fig. 3), to a lesser extent Juncus maritimus (Fig. 4), and to 
a lesser extent still because transplants were not locally abundant, 
Spartina maritima (Fig. 5). These experimental plantings were designed 
to determine transplant response to conventional ammonium sulfate + 
concentrated superphosphate and slow release (Mag Amp and Osmocote) 
fertilizer materials at different rates over a wide range of tidal 
elevations. All transplants were taken from the natural marshes at lie 
Grande and Kerlavos. Digging of transplants was confined to small 
areas along narrow drainageways (Fig. 6) and protected sites so as to 
impact the marsh as little as possible. Half of the 2900 May 
transplants were plugs (10 to 15 cm deep cores from 5 to 7 cm in 
diameter composed of root material with attached substrate) and half 
were sprigs (root material only) (Figs. 7, 8, 9). Holes for the 
transplants were made with a 6.5-cm diameter soil auger (Fig. 10). 
Transplants were spaced 0.5 m apart and the appropriate amount of 
fertilizer material was placed into the transplant hole prior to 
insertion of the transplant (Fig. 11). Planting was conducted just 
prior to the spring tide cycle so that transplants would be flooded 
shortly after planting. 




FIGURE 3. Puccinellia maritima. 



367 




FIGURE 4. Juncus maritimus. 




FIGURE 5. Spartina maritima . 



368 




FIGURE 6. Digging Puccinellia along a narrow drainageway. 




M 




f J 





1 

i 

M 


I 






FIGURE 7. Transplants of Puccinellia : sprig on left, plug on right. 



369 



J 






■ ■ 

wk 




FIGURE 8. Plug type transplants of Juncus . 




j|i 



I 



FIGURE 9. Pluy type transplants of Spartina . 



370 




FIGURE 10. A 6.5-cm diameter soil auger used to make holes for 
transplants in experimental plantings. 




FIGURE 11. Osmocote (a slow release fertilizer material) + 
concentrated superphosphate. Black cup measures a 
dose of fertilizer (2.8 g N + 1.2 g P) per 
transplant. Holes for transplants are spaced 0.5 m 
apart. 



371 




FIGURE 12. Triglochin maritima. 




FIGURE 13. Plug type transplants of Triglochin . 



372 



In September, we made 9 additional plantings of Juncus maritimus , 
Puccinellia maritima, and Spartina maritima and established initial 
plantings of another species, Triglochin maritima (Figs. 12, 13). 
Although not recognized as such on our initial visits to the site, the 
latter species appears to be a common pioneer species on disturbed 
sites alone or with Puccinellia maritima . Both Puccinellia and 
Triglochin appear to invade by seed. 

Height, number of stems, cover (a measure of spread) and 
aboveground dry weight per transplant were determined in September 
1979, 4 months after planting. Cover determinations were made by 
measuring the average maximal diameter and the average minimal diameter 
of the transplant and using these dimensions in the formula for the 
area of an ellipse. Percent survival by transplant type and species 
was also assessed at this time and at each subsequent visit. Because 
our major objective was to establish vegetation, destructive sampling 
for biomass determinations was held to a minimum of three samples per 
treatment per location. A photographic record of all plantings was 
initiated. 



1980 Plantings 

Based on results of our 1979 plantings, we established 14 
additional plantings at higher elevations in May 1980 utilizing plugs 
of Puccinellia , Juncus , Spartina , and Triglochin and sprigs of 
Halimione (Figs. 14, 15). Remains of stems and intact root systems of 
Halimione indicated that this species was the dominant along the creek 
banks prior to the Amoco Cadiz oil (Fig. 16). Consequently, we began 
preliminary tests of reestablishing this species along the creek banks 
(Fig. 17) and included it in an experiment to determine the feasibility 
of nursery production for transplants. Like the earlier plantings, 
these 1980 plantings were designed to determine transplant response to 
fertilizer materials at different rates over a range of substrate and 
exposure conditions. Cover was determined for selected plantings. All 
experimental plantings were surveyed to determine relative elevations, 
i.e. relative to the natural marshes (Fig. 18). 

In September we made 8 additional plantings using primarily 
Puccinellia and Halimione with some Spartina . Based on results from 
our earlier plantings, further planting of Triglochin seemed 
impractical. As in September 1979, all earlier plantings were assessed 
for survival, height and cover with sampling for dry weight 
determinations limited to only two plantings. Photographic 
surveillance was considered even more important because we did not 
conduct intensive destructive sampling. 



373 




FIGURE 14. Halimione portulacoides . 




FIGURE 15. Sprig type transplants of Halimione. 



374 




FIGURE 16. Creek bank without vegetation as a result of removal of 
oil and vegetation in cleanup operations. Old root 
systems of Halimione are visible on lower portion of 
banks. Note lack of natural marsh plant invasion of these 
sites at time of photo, May 1980. 




FIGURE 17. Making transplant holes along creek banks, May 1981. 
Experimental plantings made in May 1980 are visible in 
background on creek bank. 



375 




FIGURE 18. Surveying to determine the elevation of our plantings in 
relation to that of the natural marsh at lie Grande, May 
1981. Note transplants on creek banks between surveyors 
and on right creek bank toward the village from the white 
stake . 



1981 Plantings 

Based on results of all earlier plantings, we established 2 1 
additional experimental plantings in May 1981 utilizing about 4900 
transplants at lie Grande. Most of the planting effort was 
concentrated on establishing cover on the bare creek banks which were 
at this time beginning to erode due to decay of the binding root mat 
and undercutting by tidal waters (Fig. 19). Two rows of Halimione 
transplants (sprigs) were planted on the edge of the creek banks with 
two rows of Puccinellia transplants (plugs) adjacent to and toward the 
marsh along several intertidal creeks (Fig. 20). Many other areas, 
still bare of vegetation 2 years after the catastrophe, were planted to 
increase the probability of revegetation (Figs. 21, 22, 23). All 
transplants were spaced 0.5m apart. Cover was determined for selected 
plantings. All experimental plantings were surveyed to determine 
relative elevations, and the photographic record was continued. 



376 




FIGURE 19. Eroding creek bank at He Grande, May 1981 



i**:-. 







'f/V^-w • 



/! if^V 









<W 



FIGURE 20. Creek banks that had no vegetation over 2 years after the 
catastrophe. Each bank was planted with two rows of 
Halimione sprigs in May 1981. 

377 




FIGURE 21. Site at lie Grande without vegetation prior to planting in 
May 1981. 




FIGURE 22. Making holes for transplants and applying fertilizer in 
preparation for planting at same site as shown in Figure 
21, May 1981. 

378 






'^^Wr 



./".#" 



rst^ 



-•: 




s8H.*r 






FIGURE 23. Same site as that in Figures 21 and 22 just after planting 
Puccinellia in interior and Halimione on the perimeter of 
area, May 1981. 



Nursery Plantings 

It was obvious from our initial visit to lie Grande that 
transplant sources could become exhausted as we began scaling up the 
planting operation. With rehabilitation of larger areas as a goal, we 
explored the possibility of establishing nursery areas for two of the 
most promising species, Puccinellia and Halimione . The Puccinellia 
nursery area was established at Kerlavos in May 1979 in conjunction 
with a type of transplant and fertilizer materials experiment. The 
nursery area for Halimione was incorporated into a fertilizer materials 
experiment with three other species at lie Grande in May 1980. Both 
areas were refertilized with Mag Amp + Osmocote to determine the effect 
of fertilizer in addition to that applied at planting (Fig. 24). A 
limited number of transplants were taken from each nursery area in May 
1981 and compared with transplants of the same species taken from the 
natural marsh in experimental plantings at lie Grande. 

Another approach to the problem of transplant propagation was 
undertaken in a joint venture with Monsieur Levasseur in 1981 . He took 
Puccinellia plants from a natural marsh, transplanted them into small 
plastic pots, and grew them in his garden in Rennes for several weeks 
in the spring (Fig. 25). These transplants were planted in an 
experimental plot at lie Grande in May 1981 to compare their growth 
response with transplants taken from the natural marsh at the time of 
planting (Fig. 26). 

379 




FIGURE 24. Puccinellia 



transplants in September 1981 being 
refertilized with Mag Amp + Osmocote 16 months after 
planting at Kerlavos. 




FIGURE 25. Puccinellia transplant grown by Monsieur Levasseur in his 
garden for several weeks prior to planting at lie Grande, 
May 1981. 



380 




FIGURE 26. Experimental planting established with transplants shown in 
Figure 25, May 1981. 



Data Analysis 

Data were analyzed using the Statistical Analyses System (SAS) 
programs for analysis of variance and least significant difference 
(LSD) (Barr et al., 1976). All statistically significant differences 
were determined at the .05 level. Variability was generally high and 
not all data could be analyzed statistically. We feel that in field 
experiments of the type conducted on disturbed marsh sites that overall 
observations, photographs, and at times fragmentary data have to be 
interpreted and used as best they can even when statistical 
significance cannot be documented. Consequently, because of these 
conditions and the fact that data of this type are not readily 
available, we have included data in this report that we consider 
important even though the variability is high. 



381 



RESULTS AND DISCUSSION 



Substrate 

Results of analyses of substrate samples from lie Grande indicated 
important differences among sites which affect plant growth. Samples 
from relatively undisturbed areas of marsh from which transplants were 
taken and from the root mat of marsh killed by oil but with no surface 
manipulation, had relatively high ammonium, phosphorus and organic 
matter concentrations and low volume weight and pH values compared to 
substrate below the undisturbed root mat and that exposed by the 
cleanup operations (Table 1 ) . The low ammonium and phosphorus 
concentrations of the subsurface material definitely were limiting to 
plant growth. Data to be presented later in the report indicate that 
fertilizer materials were necessary for significant plant growth in 
these disturbed substrates. 



TABLE 1. Values for five substrate variables for seven sites (source 
of transplant sites for four species, two strata of marsh 
without vegetation but with surface not removed, upper 
stratum of a creek bank without vegetation but with surface 
not removed, and a site from which the marsh surface was 
removed) at lie Grande. 



Site 







Organic 




Volume 


Ammonium 
(mg/dm 3 ) 


Phosphorus 
(mg/dm 3 ) 


matter 
(%) 


pH 


weight 
(g/cc) 



Puccinellia site 

Triglochin site 

Juncus site 

Spartina site 

Marsh without vegetation 3 

upper 10 cm (root mat) 

below root mat 
Creek bank (upper 10 cm) a 
Site with marsh removed 13 



88 


12 


8.9 


3.4 


0.7 


67 


30 


8.3 


5.4 


0.7 


56 


19 


6.5 


6.0 


1.0 


117 


15 


5.8 


3.3 


0.8 


50 


32 


4.8 


5.9 


0.7 


14 


7 


0.6 


7.1 


1.4 


40 


17 


3.5 


4.7 


1.0 


5 


2 


0.0 


7.0 


1.2 



a Marsh vegetation removed as a result of cleanup operations but 
marsh surface not removed; examples of site in Figures 1 and 16. 

Marsh surface including root mat was removed during cleanup 
operations. 



382 



Elevation 

All elevations are given in relation to the average elevation of 
the natural marsh at the particular site, lie Grande or Kerlavos. At 
lie Grande the average elevation of the Juncus marsh on the southwest 
side of the bridge was the reference datum. This average elevation is 
tied to a white mark on the rock wall of the bridge for which 
Mademoiselle Odile Guerin, who has worked on the lie Grande project, 
has elevation tied to a national datum. The average elevation is also 
tied to the concrete foundation of the bridge itself. At Kerlavos the 
average elevation of the marsh is tied to a bench mark at an electric 
station tower ca . 0.5 km from the study site. Based on relating water 
levels at the two sites, the Juncus marsh at lie Grande is about 0.1 m 
above the elevation of the natural marsh at Kerlavos. 

At lie Grande we planted Juncus , Puccinellia , Spartina and 
Triglochin over a range of elevation from 0.8 m below to 0.3 m above 
the average elevation of the natural Juncus marsh. Juncus transplants 
did not survive at elevations below that of the natural Juncus marsh 
and best survival occurred at 0.3 m above that of the natural Juncus 
marsh. Puccinellia transplants did not survive at elevations of 0.7 m 
below that of the natural Juncus marsh and survival was less than 10% 
at elevations of 0.5 m below that of the natural Juncus marsh. The 
best growth and survival of Puccinellia transplants was achieved in the 
range of elevation between 0.1 m below and 0.3 m above that of the 
natural Juncus marsh. Spartina transplants survived at the lowest 
elevations of all species tested. Although Spartina transplants 
survived at elevations of 0.8 m below that of the natural Juncus marsh, 
growth was best at 0.3 m below that of the natural Juncus marsh. 
Survival and growth of Triglochin was generally poor but its elevation 
response was similar to that of Puccinellia with no survival at 
elevations of 0.7 m below that of the natural Juncus marsh. 

At Kerlavos experimental plantings of Puccinellia and Triglochin 
were established over a range of elevation from 0.5 m below to 0.1 m 
below that of the natural marsh. The best survival and growth of these 
Puccinellia transplants occurred at 0.2 m below that of the natural 
marsh. Transplants at 0.4 m below the elevation of the natural marsh 
did very poorly. Triglochin transplants responded in a similar manner. 

Halimione was planted at elevations from 0.1 m below to 0.3 m 
above that of the natural marsh at lie Grande. Survival and growth of 
these transplants were best at about 0.3 m above the elevation of the 
natural marsh, but survival was good throughout the range of elevations 
planted. At Kerlavos, Halimione was planted from 0.4 m below to 0.2 m 
below the elevation of the natural marsh. Survival and growth was best 
in the upper half of this elevation range. 



Plantings in General 

About 9,700 transplants have been planted at lie grande and about 
1,800 others at Kerlavos over the period May 1979 through May 1981 
(Table 2). Although half of these transplants were those of 

383 



TABLE 2. Number of transplants planted at lie Grande and Kerlavos for 
five species for five dates from May 1979 to May 1981 . 



Species 



Number of transplants 3 by year by month by site 5 - 1 

1979 1980 1981 

May Sep May Sep May 

IG K IG K IG K IG K IG K 



Halimione c 














332 


108 


220 





2756 





Juncus 


518 d 





173 





360 

















Puccinellia 


1298 d 


718 d 


180 


80 


448 


645 


179 


40 


2186 





Spartina 


258 d 





62 





105 





85 











Triglochin 








117 


40 


447 


105 














Total 


2074 d 


718 d 


532 


120 


1692 


858 


484 


40 


4942 






a All transplants were plugs except as otherwise noted. 

b IG = lie Grande, K = Kerlavos. 

c All transplants were sprigs. 

d Half were sprigs and half were plugs in May 1979. 



Puccinellia , four other species were also studied intensively. We 
tested two different types of transplants of four species, spring 
versus fall planting for four species, conventional and slow release 
fertilizer materials over a wide range of substrate and elevation 
conditions for five species, and developed nursery areas for two 
species. These comparisons and tests resulted in the establishment of 
61 separate experiments and plantings over about 0.3 ha (Figs. 27, 28, 
29, 30). The smallest experiment contained only 27 transplants while 
the largest contained over 1,000 transplants. The results from 
selected plantings are contained in the sections of this report that 
follow. 

Although quantitative measures (survival, cover and dry weight) 
are important in assessing transplant response to fertilizer materials 
and local site conditions, qualitative measures of plant response such 
as sequential photographs can also be revealing and supplement data. 
One of our best documented experimental plantings is at Kerlavos where 
we compared sprigs and plugs of Puccinellia in several fertilizer 
treatments. The planting was established in May 1979 and after 
realizing the initial objectives, we refertilized the area to develop a 
nursery for Puccinellia transplants. The pictorial sequence shows the 
site prior to planting (Fig. 31), immediately after planting and 
initial fertilization (Fig. 32), 1 year after planting (Fig. 33), and 2 
years after planting, 8 months after refertilization (Fig. 34). 



384 




FIGURE 27. Map of study area on northwest side of the bridge at He 
Grande showing location of experimental plantings 
(stippled areas). Base map by Monsieur Levasseur. 

385 




<^ 



FIGURE 28. Map of study area on southeast side of bridge at lie 
Grande showing location of experimental plantings 
(stippled areas). Base map by Monsieur Levasseur. 

386 



XLE 



^ftflMae 




FIGURE 29. Map of study area on northwest side of estuary at lie 
Grande beyond area in Figure 28 from bridge showing 
location of experimental plantings (stippled areas). Area 
is just beyond road from village to several houses on edge 
of estuary. Base map by Monsieur Levasseur. 

387 




Keri&vos 



FIGURE 30. Map of study area in estuary at Kerlavos showing location 
of experimental plantings (stippled areas). Base map by 
Monsieur Levasseur. 



388 




FIGURE 31. Site for experimental planting at Kerlavos prior to 
planting in May 1979. 




FIGURE 32. Same site as in Figure 31 just after planting with 
Puccinellia sprigs and plugs on 0.5-m spacing in 
May 1979. 



389 



^~~ -<- .* -,- s -c w ».-^ -*t SET- 





FIGURE 33. Same site as in Figure 32 in May 1980, 1 year after 
planting. There are six rows of sprigs and six rows of 
plugs which alternate with each other beginning with a row 
of sprigs on the extreme left. The tallest plants in the 
center are plugs in the Mag Amp + Osmocote fertilizer 
treatment. 




FIGURE 34. Same site as in Figure 3 2 in May 1981, 2 years after 
planting. The planting is now a Puccinellia nursery 
area. 

390 



Survival 

In September, 4 months after our initial planting, the survival of 
plugs was significantly greater than that of sprigs for all three 
species (Table 3). Survival averaged over transplant type was about 
65% for both Puccinellia and Spartina but only about 50% for Juncus. 
Reevaluation of these May 1979 transplants 1 year after planting 
indicated that significant mortality of both transplant types occurred 
over winter (Table 3). Greater overwinter mortality occurred in plug 
than in sprig transplants for both Puccinellia and Juncus . These 
results suggest that whatever factors were causing mortality in the 
sprigs were still affecting the plugs and that it was simply taking 
longer to cause mortality in the larger transplant type. Overall 
survival was less than 50% for both transplant types for all species, 
but still significantly higher for plugs than for sprigs. These 
relatively low survival percentages included plantings in unfavorable 
(low elevation, exposed, poorly drained) locations, since we were 
trying to determine response over a wide range of conditions. In the 
more favorable sites, at about the elevation of the natural Juncus 
marsh, survival of plug transplants was consistently above 70% for 
Puccinellia . On those planting sites where 10% or more of the 
transplants survived through the second year, plugs continued to 
survive better than sprigs for Puccinellia and Juncus (Table 4). Of 
all the 1979 transplants, only those of Puccinellia on the better sites 
yielded survival values of greater than 60%. 



TABLE 3. Percent survival at 4 and 12 months for two types of 
transplants 3 for three species for the combined plantings 
made at lie Grande and Kerlavos in May 1979. 

Survival (%) by time" by type 

Species 4 months 12 months 



Sprig Plug Sprig Plug 



Juncus 


22 
48 


80 


Puccinellia 


84 


Spartina 


56 


80 


Averaged over species 


44 


84 



14 


37 


31 


47 


10 


26 


29 


37 



a There were 230, 979, and 100 transplants of each type for Juncus , 
Puccinellia and Spartina , respectively. 

b Survival of plugs was significantly greater than that of sprigs 
within and over all three species at each of the two sampling periods 
based on chi-square analysis. The reduced survival of both transplant 
types over species between the two sampling periods was also 
significant based on chi-square. 



391 



TABLE 4. Survival of two types of transplants of three species 1 and 2 
years after planting (May 1979) averaged over all locations 
on more favorable sites. 



Survival (%) a 



64 


87 


4 


39 


10 


26 



63 


82 


2 


23 


4 


10 



Species May 1980 May 1981 

Sprig Plug Sprig Plug 



Puccinellia 

Juncus 

Spartina 



a There were 379, 120 and 50 transplants planted of each type for 
Puccinellia , Juncus and Spartina , respectively. 



Except for Puccinellia transplants, these survival data from May 
1979 plantings are not impressive. We were in the process of learning 
where to plant with regard to elevation, the best type of transplant to 
use, the appropriate species, whether spring was better than fall 
planting, and how to satisfy the nutrient requirements of the 
transplants with fertilizer materials. Survival data for the May 1980 
plantings indicate a significant increase in survival over those of the 
earlier plantings (Table 5). These results indicate that we were 
making progress and that except for Juncus , survival values greater 
than 50% were achieved for all species tested. The seemingly erroneous 
survival value for Halimione 4 months after planting is due to 
aboveground material appearing dead but the underground material being 
alive and giving rise to new aboveground growth the following spring. 
A decrease in survival overwinter of greater than 14% was only noted 
for Juncus which experienced a 41% decrease. Spring appears to be a 
better season to transplant than fall but the data are incomplete at 
this time. 



Type of Transplant 

The best comparison between sprig and plug transplants of 
Puccinellia from our experiments is the data from Kerlavos where cover 
and survival were higher for plug transplants except for the 
conventional ammonium sulfate + concentrated superphosphate treatment 
where the cover of sprigs was higher than that of plugs (Table 6, Fig. 
33). The reduced survival for both types of transplants and especially 
sprigs in the ammonium sulfate + concentrated superphosphate (2.8 g N + 
4.1 g per transplant) treatment was due to a small depression without 
exterior drainage which occupied a portion of this treatment and in 
which transplants did not survive (Fig. 33). Increased salinity due to 
evaporation or waterlogged substrate conditions due to prolonged 
ponding could have contributed to the reduced survival of this 
treatment. Although this drainage condition was restricted to a small 

392 



TABLE 5. Survival of sprig type Halimione transplants and plug type 
transplants of four other species at two sampling dates 
averaged over all locations; planted May 1980. 



Species 



Sep 1980 



Survival (%) a 



May 1981 



Halimione 

Juncus 

Puccinellia 

Spartina 

Triglochin 



45 
80 
95 
96 
82 



52 
39 
83 
89 
68 



a There were 440 Halimione , 360 Juncus , 823 Puccinellia , 
Spartina , and 822 Triglochin transplants planted. 



105 



TABLE 6. Cover in September of 1979 and 1980 and survival in September 
1980 for sprig and plug type Puccinellia transplants for six 



fertilizer 


treatments 


at Kerlavos; 


planted 


May 


1979. 






Amount 


(g) 




Cover 


(cm 2 ) a 




Survival 




per 












(%) b 


Treatment 


transplant 


Sep 


1979 


Sep 1980 


Sep 


1980 




N 


P 


Sprig 


Plug 


Sprig 


Plug 


Sprig 


Plug 


Control 








34 


91 


46 


174 


65 


95 


Ammonium sulfate 


2.8 


1.2 


249 


128 


338 


292 


78 


95 


Mag Amp + Osmocote 3 


2.8 


4. 1 


77 


260 


234 


533 


50 


83 


Ammonium sulfate 


2.8 


4.1 


154 


188 


177 


275 


40 


70 


Ammonium sulfate 


2.8 





79 


108 


135 


264 


75 


95 


Coned superphosphate 





1.2 


62 


107 


145 


206 


75 


78 


Avg. over treatment 






109 


147 


152 


291 


64 


86 



a Cover was ca. 



for sprigs and ca. 25 cm" 1 for plugs at 



planting. Standard error of difference between equally replicated 
transplant type means and among fertilizer treatment means: 40 for 
September 1979, 57 for September 1980, n=10. 

" There were 40 transplants of each transplant type per fertilizer 
treatment at planting. 

° Source of P was concentrated superphosphate. 



393 



area (12 m 2 ) , and was an exception to the relatively uniform 
topography of the experimental site, it served to emphasize the 
importance of adequate drainage for plantings of Puccinellia . 

When cover is averaged over treatment for the period from 
September 1979 to September 1980, the cover value for plugs increased 
two fold whereas that for sprigs increased by about 40%. Average 
survival over this same period of time was 22% higher for plugs than 
for sprigs. Sixteen months after planting, cover for plugs was 
significantly higher in the Mag Amp + Osmocote 3 (estimated to last for 
3 months) treatment and for sprigs it was significantly higher in the 
ammonium sulfate + concentrated superphosphate treatment (2.8 g N + 1.2 
g P). The controls achieved only 14 and 33% of the cover of the best 
treatments for sprigs and plugs, respectively, over this 16-month 
period. 



Response to Fertilization 



Kerlavos 

Analysis of variance of cover and dry weight data of plug type 
transplants of Puccinellia on a disturbed site at Kerlavos indicated a 
significant response to fertilizer materials (Tables 7, 8). One year 
after planting the cover of plugs in all three fertilizer treatments 
containing both nitrogen and phosphorus was significantly greater than 
that of plants in those treatments which provided only nitrogen or 
phosphorus or neither (Table 7). These results emphasize the 
requirement for fertilizer materials on those disturbed sites which 
substrate samples indicated contained amounts of nitrogen and 
phosphorus which were too low for good initial growth of transplants. 

The dry weight of aboveground plant samples from the Mag Amp + 
Osmocote 3 slow release fertilizer treatment was significantly greater 
than that of plants from any other treatment at 4 and 16 months after 
planting (Table 8). Although cover in the Mag Amp + Osmocote 3 
treatment was not significantly different from that in the two 
conventional ammonium sulfate + concentrated superphosphate treatments 
1 year after planting, by 16 months after planting, cover of plants in 
this Mag Amp + Osmocote 3 treatment was significantly greater than that 
of those in any other treatment. Cover of plants in this treatment was 
about twice that of transplants in the second best treatment. The 
center row of transplants (plugs) in Figure 3 3 is the Mag Amp + 
Osmocote 3 treatment. These data indicate the advantage of a slow 
release over a conventional fertilizer material on this disturbed site 
for a relatively long period (16 months). We excavated the belowground 
portion of several healthy transplants in the Mag Amp + Osmocote 3 
treatment and noted that the fertilizer material still present below 
the transplant could be identified after 4 months (Fig. 35). 

Cover in the control plants remained significantly below that of 
plants in those three treatments which provided both nitrogen and 
phosphorus 16 months after planting. Cover in these control plants was 

394 



TABLE 7. Cover of plug-type Puccinellia transplants on three sampling 
dates for six fertilizer treatments at Kerlavos; planted May 
1979. 







Amount 


(g) 












per 
transplant 




Cover (cm 2 ) a ' b 




Treatment 












N 


p 


May 1980 


Sep 1980 c 


May 1981 


Control 










66 


174 


388 


Ammonium 


sulfate d 


2.8 


1.2 


122 


292 


638 


Mag Amp + 


Osmocote 3 


2.8 


4. 1 


209 


533 


819 


Ammonium 


sulfate d 


2.8 


4.1 


187 


275 


687 


Ammonium 


sulfate 


2.8 





73 


264 


481 


Coned superphosphate 





1.2 


106 


206 


501 


Avg. over 


treatment 






127 


291 


586 



a Cover of a plug at planting was ca. 2 5 cm 2 . 

k Standard error of difference among equally replicated fertilizer 
treatment means: 48 for May 1980, 49 for September 1980, 107 for May 
1981; n=10. Comparison of initial fertilizer treatments for May 1981 
may not be entirely appropriate because of the refertilization. 

c Refertilized with Mag Amp + Osmocote 3 (2.8gN + 4.1 gP per 
transplant) in September 1980 after data collection. 

d Source of P was concentrated superphosphate. 



395 



TABLE 8. Aboveground dry weight of plug type Puccinellia transplants in 
September 1979 and 1980 for six fertilizer treatments at 
Kerlavos; planted May 1979. 





Amount 


(g) 


Aboveground 






per 






dry 


wt 




transplant 




(g: 


l a 


Treatment 


N 




p 


Sep 1979 




Sep 1980 


Control 










1.9 




10.7 


Ammonium sulfate 


2.8 




1.2 


3.8 




23.3 


Mag Amp + Osmocote 3 


2.8 




4.1 


10.1 




52.5 


Ammonium sulfate 


2.8 




4.1 


4.5 




22.1 


Ammonium sulfate 


2.8 







3.3 




14.6 


Coned superphosphate 







1.2 


3.1 




15.5 


s- c 

s d 








3.0 




6.2 



a Aboveground dry weight at planting was less than 1 g. 

" Source of P was concentrated superphosphate. 

c Standard error of difference among equally replicated fertilizer 
treatment means, n=3. 




FIGURE 35. Excavated Puccinellia transplant 4 months after 
planting showing new roots (white) and slow release 
fertilizer material still in place. 



3 96 



significantly below that of those same three fertilizer treatments 2 
years after planting even though these initial control plants were 
fertilized with Mag Amp + Osmocote 3 in September 1980. Although 
comparison of the original fertilizer treatments is confounded and may 
not be entirely appropriate in May 1981 since all transplants were 
refertilized in September 1980, it is interesting to note that the same 
three fertilizer treatments with both nitrogen and phosphorus continued 
to have cover values which were significantly higher than those of 
plants in any other treatment. Cover of transplants in the best 
fertilizer treatment achieved an average radial spread of about 10 cm 
annually (Fig. 36). At this rate of spread, these Puccinellia plants 
would achieve complete substrate cover in about 3 years after planting 
(Fig. 37). 




FIGURE 36. A 2-year old Puccinellia transplant with an average 
diameter of ca. 60 cm and cover of ca. 2,800 cm^ or 112 
times that of the transplant at planting. 



397 






,^-^ 








FIGURE 37. Several 2-year old 
planted 0.5 m apart. 



Puccinellia transplants that were 



The substrate should be completely 
covered by these plants by May 1982. 



lie Grande 

Analysis of variance of cover data of Halimione and Puccinellia 
transplants 1 year after planting on a disturbed site at lie Grande 
indicated a significant response to fertilizer materials (Table 9). 
Best growth as measured by cover was achieved by both species in the 
Mag Amp + Osmocote 3 treatment (Table 9, Figs. 38, 39). Cover of 
Halimione transplants in this treatment was significantly higher than 
that of transplants in any other treatment except for the Osmocote 8-9 
(estimated to last 8 to 9 months) + concentrated superphosphate 
treatment. The cover data for Puccinellia transplants indicate the 
advantage of slow release over conventional fertilizer materials at 
this particular site. Apparently leaching of the conventional 
fertilizer materials was a problem because of the coarse sandy 
substrate in this planting. Significantly greater cover of Puccinellia 
was produced by the slow release fertilizer treatments than by ammonium 
sulfate + concentrated superphosphate except where the rate of ammonium 
sulfate was doubled (5.6 g N per transplant). 

Differences among the cover values of the Triglochin transplants 
are meaningless except to document the poor growth by this species 
under all experimental treatments. The response by Triglochin in the 
particular experiment is representative of its response at several 
experimental sites and is the reason for our decision to delete it from 



398 



TABLE 9. Cover and survival of transplants of three species in May 1981 
for nine fertilizer treatments at lie Grande, planted May 
1980. 





Amount 


(g) 


















per 




Cover 


(cm 2 ) 3 




Survival (%) 


b 




transplant 


by 


species 




by 


species 




Treatment 


N 


p 


H 




P 


T 


H 


P 


T 


Control 








326 




319 


26 


100 


100 


87 


Ammonium sulfate 


2.8 





108 




305 


14 


60 


100 


73 


Ammonium sulfate" 


2.8 


1.2 


128 




302 


25 


67 


100 


93 


Ammonium sulfate" 


5.6 


1.2 


100 




460 


12 


100 


100 


93 


Mag Amp + Osmocote 3 


2.8 


4.1 


535 




725 


23 


100 


100 


60 


Osmocote 3 


2.8 


1.2 


277 




556 


14 


67 


100 


93 


Osmocote 8-9 


2.8 


0.4 


228 




449 


31 


73 


100 


73 


Osmocote 8-9 


5.6 


0.8 


272 




578 


9 


73 


100 


60 


Osmocote 8-9 e 


2.8 


1.2 


366 




611 


21 


60 


100 


93 


*a £ 






103 




93 


7 









a Cover of a plug transplant for Puccinellia and Triglochin was ca. 
25 cm 2 at planting; n=14 for Puccinellia , n=8 for Triglochin . Sprigs 
of Halimione had quite variable cover at planting, but generally less 
than 50 cm 2 ; n=8. 

° There were 15 transplants per treatment for each species. 

° H = Halimione , P = Puccinellia , T = Triglochin . 

" Source of P was concentrated superphosphate. 

e Source of additional P was concentrated superphosphate. 

f Standard error of difference among equally replicated treatment 
means . 



399 







FIGURE 38. Experimental planting at lie Grande to determine response 

to fertilizer by four species, from right of stake: 

Puccinellia , Triglochin , Halimione , and Juncus just after 
planting in May 1980. 




FIGURE 39. Same experimental planting as shown in Figure 39 in May 
1981, 1 year after planting. First seven plants in 
foreground were refertilized with same fertilizer 
materials as in initial treatments (Table 9) in September 
1980, 4 months after planting. 



400 



further consideration as a desirable species in our rehabilitation 
efforts. 

The relatively high survival of all three species indicates a 
marked improvement in our selection and handling of transplants as well 
as the selection of a favorable planting site. These survival 
percentages were based on 135 transplants per species in this 
particular experiment. The high survival of Puccinellia transplants 
coupled with the relatively high cover values as compared to those of 
the other two species indicates that our emphasis on this species is 
justified. 

Analysis of variance of cover data indicates that the Osmocote 8-9 
slow release fertilizer material maintained the original cover of 
Spartina transplants at planting with very little growth through the 
first year (Table 10). Transplants in the control and ammonium sulfate 
+ concentrated superphosphate treatments decreased in cover over the 
first year. Although growth was not good, survival of these and other 
1980 Spartina transplants was consistently above 80% (Table 5, Figs. 
40, 41). Growth of this species has been very slow in all our 
experimental plots but because it can occupy lower elevations than most 
of the other species, we plan to continue to experiment with it on a 
limited scale. 



TABLE 10. Cover and survival of plug type Spartina transplants in May 
1981 for three fertilizer treatments at lie Grande; planted 
May 1980. 







Amount 


(g) 










per 
transpl 


ant 


Cover 3 


Survival" 


Treatment 




N 




P 


(cm 2 ) 


(%) 


Control 












11 


93 


Ammonium sulfate 


2 


.8 




1.2 


15 


100 


Osmocote 8-9 d 


2 


.8 




1.2 


29 


80 



a Cover of a plug transplant at planting was ca. 25 cm 2 . Standard 
error of difference among equally replicated treatment means = 6.1, 
n=6. 

" There were 15 transplants per treatment planted. 

c Source of P was concentrated superphosphate. 

d Source of additional P was concentrated superphosphate. 



401 



fr J1MI 




FIGURE 40. Experimental plantings of Spartina at He Grande to 
determine transplant response to fertilizer 
materials just after planting in May 1980. 




FIGURE 41. Same experimental planting as shown in Figure 40 in 
May 1981, 1 year after planting. 



402 



Response to Ref ertilization 

Analysis of variance indicated that refertilized Puccinellia 
transplants produced significantly more cover than those not 
refertilized (Table 11). Without ref ertilization transplant cover 
increased by 2.1 times from September 1980 to May 1981 whereas with one 
ref ertilization in September 1980 cover increased 2.9 times by May 
1981. Those plants refertilized tiwce (May and September 1980) 
increased their cover 3.8 times by May 1981 or by 1.9 times between May 
and September 1980 and by 1.9 times between September 1980 and May 
1981. One ref ertilization increased cover 1.4 times that of the plants 
which were not refertilized over an 8-month period and two 
ref ertilizations increased cover 1.8 times that of the unref ertilized 
plants over a period of 1 year. 



TABLE 11. Cover of Puccinellia transplants at two sampling dates for 
three fertilizer treatments 3 at Kerlavos, planted May 1979. 



Treatment 



Cover (cm 2 ) b 
Sep 1980 May 1981 



Not fertilized 
Refertilized Sep 1980 c 
Refertilized May 1980 d 
and again Sep 1980 c 



222 
221 

428 



460 
645 
833 



a All treatments were fertilized in May 1979 at planting. 

b Standard error of difference among equally replicated treatment 
means = 115, n=1 1 . 

c Refertilized with Mag Amp + Osmocote 3 (2.8 g N, 4.1 g P per 
transplant) . 

d Refertilized with Osmocote 8-9 + P (2.8 g N + 1.2 g P per 
transplant) . 



Response to Fresh Oil 

In the spring of 1980 oil from the Tanio reached the estuary at 
Kerlavos. Although it was observed on several of our 1979 transplants, 
we could not document any adverse effects. We decided to take 
advantage of the opportunity to plant in some of the fresh oil deposits 
along a creek bank. The marsh surface of the planting site had been 
removed in a cleanup of Amoco Cadiz oil earlier. The fresh Tanio oil 
was a superficial layer on the substrate which did not appear to 
penetrate into the substrate. In May 1980 transplants of Halimion e and 



403 



Puccinellia were planted at one of these freshly oiled sites (Fig. 42). 
Cover and survival data determined 1 year later indicate no noticeable 
effect of the oil on either species (Table 12, Fig. 43) as compared to 
these data from transplants at unoiled sites which were planted the 
same year (Table 9). As in many other experiments, cover data 
indicated a significant transplant response to fertilizer materials 
with best growth realized in the Osmocote slow release treatment. 



TABLE 12. Cover and survival of Halimione (sprigs) and Puccinellia 
(plugs) transplants in May 1981 at a site oiled by the Tanio 
in the spring 1980; planted May 1980. 



May 1981 



Treatment 



Amount (g) 

per 
transplant Cover 
N P ( cm 2 ) a 



Halimione 



Survival 
(%) 



Puccinellia 



Cover 
( cm 2 ) a 



Survival 
(%) 



Control 








86 


Ammonium sulfate 


2.8 


1.2 


258 


Osmocote 8-9 c 


2.8 


1.2 


631 



67 

100 

67 



381 
493 
550 



100 

67 

100 



a Cover of Halimione sprigs was quite variable at planting, but was 
generally less than 50 cm 2 ; that of a Puccinellia plug was ca. 25 
cm 2 . Standard error of difference among equally replicated treatment 
means; 100 for Halimione , 160 for Puccinellia , n=3. 

" Source of P was concentrated superphosphate. 

c Source of additional P was concentrated superphosphate. 



Creek Bank Plantings 

Creek banks with no vegetation cover are one of our top priority 
planting sites. Preliminary plantings of Halimione made in May 1980 
(Fig. 44) achieved over 90% survival and good growth by the following 
May (Fig. 45). Puccinellia plantings have also achieved good survival 
and growth over this period of time (Figs. 46, 47). About half of the 
over 4,900 May 1981 transplants were planted along creek banks (Fig. 
20). A similar proportion of the overall planting effort is planned 
for creek bank sites in May 1982. 



404 




FIGURE 42. Planting Puccinellia and Halimione in fresh oil from the 
Tanio in the estuary at Kerlavos in May 1980. 




FIGURE 43. Same experimental planting as shown in Figure 42 in May 
1981, 1 year after planting: Puccinellia on left, 
Halimione on right. 



405 






<f-> 




FIGURE 44. Preliminary planting of Halimione sprigs along a creek bank 
at lie Grande in May 1980. 










■ ,. 

Sffl 



FIGURE 45. Same site as shown in Figure 44 in May 1981, 1 year after 
planting. 



406 



Jfitjl i m -Jfc 




FIGURE 46. Experimental planting of Puccinellia along a creek bank at 
lie Grande in May 1980 just after planting. 




FIGURE 47. Same site as shown in Figure 46 in May 1981, 1 year after 
planting. 



407 



Transplant Time Requirement 

It is difficult to determine the time involved in the 
transplanting operations when experimental plantings are being 
established. In May 1981 we kept records of the time required for four 
persons to dig and transplant sprigs of Halimione and plugs of 
Puccinellia . Halimione plants were dug, separated into sprigs and put 
into plastic bags for transport to the planting site at the rate of 
about 180 per person hour. Puccinellia plants were dug, cut into plugs 
and put into a container for transport to the planting site at the rate 
of about 75 per person hour. These rates indicate that Halimione 
sprigs can be obtained about 2.4 times faster than Puccinellia plugs. 

The planting operation includes opening the transplant hole with a 
soil auger, inserting the appropriate amount of fertilizer, and 
inserting the transplant and firming the substrate around it. Both 
types of transplants can be planted at the rate of about 40 per person 
hour. 

These time requirements for digging and planting make no allowance 
for travel, supplies, and equipment, which must also be considered in 
the total cost of a planting operation. Based on our digging and 
planting time requirements only, the time required to plant 1 ha of 
Halimione on a 0.5 m spacing (40,000 transplants) would be about 1,220 
person hours (220 person hours to dig sprigs + 1,000 person hours to 
plant). The time required to plant 1 ha of Puccinellia on a 0.5 m 
spacing would be about 1,530 person hours (530 person hours to dig + 
1,000 person hours to plant). These cost estimates indicate that it 
would take four persons working 8 hour days about 38 days to plant 1 ha 
of Halimione on a 0.5 m spacing and about 48 days to do the same using 
Puccinellia. 



Recovery of Transplant Source Sites 

From the beginning of our restoration efforts we were aware of the 
potential for impact to the natural marsh in digging transplants for 
the plantings. Consequently, we confined our digging of plants in the 
natural marsh to areas adjacent to narrow drainageways (Fig. 6) or to 
small areas (0.25 m 2 ) in the marsh. All Puccinellia transplant 
source sites were replanted and those areas that were dug in 1979 and 
1980 were almost completely revegetated by May 1981' (Figs. 48, 49). In 
a further attempt to lessen the pressure for obtaining transplants from 
the natural marsh, we have initiated nursery areas for Halimione and 
Puccinellia . These combined actions will help keep impact to the 
natural marsh to a minimum and serve as a model for others who may 
engage in similar activities in the future. 



Nursery Plantings 

The Puccinellia nursery area at Kerlavos was established in May 
1979 and now contains about 300 plants that can be dug and separated 
into transplants. Although the plants vary in size, the average cover 

408 




FIGURE 48. Site where Puccinellia transplants were dug in May 1980. 
The area was replanted and was becoming rapidly 
revegetated in September 1980, 4 months after digging. 




FIGURE 49. Same site as shown in Figure 48 in May 1981, 1 year after 
digging. Vegetation cover is almost complete. 



409 



is about 540 cm^ or over 20 times that of a plug type transplant. To 
determine the actual number of plugs that could be obtained from a 
sample of plants, we dug 11 plants from the row nearest the estuary in 
May 1981 (Fig. 50). One of the largest plants yielded 50 plugs (Figs. 
51, 52, 53), but the average number of plugs per plant dug was 20, 
which agreed well with what we predicted based on the average cover. 
Since the nursery area contains about 300 plants, we can predict that 
it could have yielded a minimum of 6,00 plug type transplants in May 
1981 . It seems reasonable to assume that cover will increase from 50 
to 100% by our next major planting effort in May 1982. This assumption 
translates into a conservative estimate of about 10,000 plug type 
transplants or enough to plant 0.25 ha on a 0.5 m spacing. 

The Halimione nursery area at lie Grande was established in May 
1980 and added to in May 1981. It contains about 200 plants that can 
be dug and separated into transplants (Fig. 54). In May 1981 we dug a 
sample of seven plants to determine the average number of sprig type 
Halimione transplants that could be obtained per plant dug. We 
obtained an average of five sprigs from each plant dug (Fig. 55). 
Based on 20 plants in the nursery area, we estimate that there were 
about 1,000 Halimione transplants available in May 1981. We estimate 
that the increase in cover by May 1982 will result in about 1,500 to 
2,000 Halimione sprigs available for digging at that time which would 
plant about 0.05 ha on a 0.5 m spacing. 




FIGURE 50. Row of 2-year old Puccinellia transplants nearest 
estuary in the nursery area at Kerlavos, May 1981. 



the 



410 




*■& 






/* 

<* 






< ■ 






FIGURE 51 



Sample Puccinellia plant that was dug for 
transplants from the same row of plants shown in 
Figure 50, May 1981 . 







FIGURE 52. Cutting the same plant shown in Figure 51 into plug 
type transplants. 



411 












FIGURE 53. Plant shown in Figure 51 yielded 50 plug type 
transplants. 






■ '"' 'J$mM 





FIGURE 54. A 1-year old Halimione transplant in the nursery 
area at lie Grande. 



412 




FIGURE 55. Halimione sprigs being dug from the nursery area at 
lie Grande. 



Invasion of Plantings by Other Plants 

Observations at lie Grande and Kerlavos indicate that other marsh 
plants invade our experimental plantings more rapidly than they 
colonize areas that still lack vegetation cover as a result of cleanup 
operations. In one of our May 1979 experimental plantings of 
Puccinellia at Kerlavos (Figs. 56, 57, 58), 97% of the transplants in 
the 60 m^ area had been invaded by at least one other species by May 
1981 (Fig. 59). Of these transplants which had been invaded, 66% were 
invaded by two or more other species. The most abundant invader was an 
annual species of Salicornia which was present in 94% of the 
transplants sampled. Other invading genera in the order of their 
percentage of presence per transplant sampled were Cochleria (49%), 
Halimione (24%), Spergularia (10%), and Armeria (1%). 



413 




FIGURE 56. Experimental planting of Puccinellia at Kerlavos in 
May 1979 just after planting. 




t- £*~'^ r 




FIGURE 57. Same experimental planting as shown in Figure 56 in 
May 1980, 1 year after planting. 



414 




FIGURE 58. Same experimental planting as shown in Figure 56 in May 
1981, 2 years after planting. 











FIGURE 59. A 2-year old Puccinellia transplant from the experimental 
planting shown in Figure 56 with two invading marsh 
plants: Cochle.ia (white flowers) and Salicornia (left 
center near cluster of white flowers). 



415 



ACKNOWLEDGEMENTS 



Cooperation with our French colleagues (Madames Le 
Campion-Alsumard, Plante-Cuny, and Vacelet from Marseille and Monsieur 
Levasseur and Mademoiselle Jory from Rennes) has been invaluable. In 
fact, our work would have just about been impossible without their 
help- They have gone out of their way to help us while we were in 
France, such as arranging a meeting with the Mayor of Pleumeur-Bodou, 
making observations on our experimental plots during the interim of our 
visits, and providing laboratory facilities for processing samples. 
Presently we are cooperating with Monsieur Levasseur on nursery 
production of transplants and monitoring of our plantings until 
November 1982. He has also agreed to serve as the major professor for 
a graduate student from the United States who is a candidate for a 
Fulbright Scholarship. Among his tasks, this student would follow our 
plantings and document the invasion of these plantings by other marsh 
plants subsequent to our active involvement in the project. In 
summary, the association with our French colleagues has been very 
beneficial from our standpoint and we cannot overemphasize the vital 
part they have played in making our research proceed smoothly. 

We thank Amoco Oil for providing the funds for our research 
through NOAA Contract No. NA79RAC00018. We thank NOAA personnel 
especially Drs . W.N. Hess and D.A. Wolfe for providing us the 
opportunity to conduct this very timely and environmentally beneficial 
research and for their cooperation throughout the period of the 
project. 

Last, special thanks for technical assistance in field work and in 
data analysis go to Messrs. C.L. Campbell and L.L. Hobbs who made the 
overall research effort a success. 



SUMMARY 



Experimental plantings of Halimione portulacoides , Juncus 
maritimus , Puccinellia maritima, Spartina maritima , and Triglochin 
maritima have been made at lie Grande and Kerlavos, France in an 
attempt to rehabilitate salt marsh that was impacted by the Amoco Cadiz 
oil spill and subsequent cleanup operations. Over 61 experimental 
plantings including over 11,000 transplants have been established to 
test two types of transplants, conventional and slow release fertilizer 
materials over a wide range of substrate and elevation conditions and 
to develop nursery areas. Spartina transplants survived at lower 
elevations than those of any other species tested, but the best growth 
of transplants of all species tested occurred within + 0.3 m of the 
elevation of the natural marsh in the vicinity. Survival and growth 
data indicate that transplants of Puccinellia with a core of root and 
substrate material intact (plugs) were superior to those transplants 
with roots only (sprigs). 



416 



Although there was considerable variation in response to 
fertilizer materials and rates, both nitrogen and phosphorus were 
required for good transplant growth on the disturbed sites tested. 
Slow release fertilizer materials produced better growth over a wide 
range of substrate types than did the conventional, more soluble 
fertilizer materials. Higher survival and better growth were obtained 
with Halimione and Puccinellia transplants than with those of the other 
three species tested. Aboveground growth of the best experimental 
plantings of Puccinellia spread radially at the rate of about 10 cm 
annually. At this rate of spread, these experimental plantings would 
achieve complete substrate cover in about 3 years after planting. 
Refertilization at various periods after planting produced a 
significant increase in cover. 

Halimione sprigs were dug at the rate of about 180 per person hour 
and plugs of Puccinellia at the rate of about 7 5 per person hour. 
Transplants of both species were planted and fertilized at the rate of 
about 40 per person hour. Sites in the natural marsh from which 
Puccinellia transplants were dug, were replanted and became almost 
completely revegetated within 1 year. Nursery areas were established 
for both Halimione and Puccinellia and estimates indicated that in May 
1981 they contained about 6,000 transplants of Puccinellia and 1,000 of 
Halimione . Preliminary data indicate that other marsh plants invade 
our plantings more rapidly than they invade unplanted disturbed sites. 



417 



LITERATURE CITED 



Baker, J. M. , 1971a, The effects of a single oil spillage: in E.B. 

Cowell (ed.), The Ecological Effects of Oil Pollution on Littoral 
Communities, pp. 16-20, Applied Science Publ . , Bristol, England, 
250 pp. 

Baker, J. M. , 1971b, Successive spillages: in E.B. Cowell (ed.), The 
Ecological Effects of Oil Pollution on Littoral Communities, 
pp. 21-32, Applied Science Publ., Bristol, England, 250 pp. 

Baker, J. M. , 1971c, Refinery effluent: in E.B. Cowell (ed.), The 
Ecological Effects of Oil Pollution on Littoral Communities, 
pp. 33-43, Applied Science Publ., Bristol, England, 250 pp. 

Baker, J. M. , 1971d, Seasonal effects: in E.B. Cowell (ed.), The 
Ecological Effects of Oil Pollution on Littoral Communities, 
pp. 44-51, Applied Science Publ., Bristol, England, 250 pp. 

Baker, J. M. , 1971e, Effects of cleaning: in E.B. Cowell (ed.), The 
Ecological Effects of Oil Pollution on Littoral Communities, 
pp. 52-57, Applied Science Publ., Bristol, England, 250 pp. 

Baker, J. M. , 1971f, Oil and salt marsh soil: in E.B. Cowell (ed.), 
The Ecological Effects of Oil Pollution on Littoral Communities, 
pp. 62-71, Applied Science Publ., Bristol, England, 2 50 pp. 

Baker, J. M. , 1971g, Growth stimulation following oil pollution: in 
E.B. Cowell (ed.), The Ecological Effects of Oil Pollution on 
Littoral Communities, pp. 72-77, Applied Science Publ., Bristol, 
England, 250 pp. 

Baker, J. M. , 1971h, Comparative toxicity of oils, oil fractions and 
emulsifiers: in E.B. Cowell (ed.), The Ecological Effects of Oil 
Pollution on Littoral Communities, pp. 78-87, Applied Science 
Publ. , Bristol, England, 250 pp. 

Baker, J. M. , 1971i, The effects of oils on plant physiology: in E.B. 
Cowell (ed.), The Ecological Effects of Oil Pollution on Littoral 
Communities, pp. 88-98, Applied Science Publ., Bristol, 
England, 250 pp. 

Cowell, E. B., 1969, The effects of oil pollution on salt-marsh 
communities in Pembrokeshire and Cornwall: J. Appl. Ecol . , 
Vol. 6, pp. 133-142. 

Cowell, E. B. and J. M. Baker, 1969, Recovery of a salt marsh in 
Pembrokeshire, Southwest Wales, from pollution by crude oil: 
Biol. Conserv. , Vol. 1, pp. 291-295. 

Garbisch, E. W. , P. B. Woller, and R. J. McCallum, 1975, Salt marsh 
establishment and development: U.S. Army, Coastal Engineering 
Research Center, Fort Belvoir, Virginia, Tech. Memo. 52, 110 pp. 

418 



Ranwell, D. S. , 1968, Extent of damage to coastal habitats due to the 
Torrey Canyon incident: in J.D. Carth and D.R. Arthue (eds.)/ The 
Biological Effects of Oil Pollution on Littoral Communities, 
pp. 39-47, Field Studies Council, London, England, 198 pp. 

Seneca, E. D., S. W. Broome, W. W. Woodhouse, Jr., L. M. Cammen, and 

J. T. Lyon, III, 1976, Establishing Spartina alternif lora marsh 
in North Carolina: Environ. Conserv. , Fol. 2, pp. 185-189. 

Stebbings, R. E. , 1970, Recovery of salt marsh in Brittany sixteen 
months after heavy pollution by oil: Environ. Poll., Vol. 1, 
pp. 163-167. 

Woodhouse, W. W. , Jr., E. D. Seneca, and S. W. Broome, 1974, 

Propagation of Spartina alternif lora for substrate stabilization 
and salt marsh development: U.S. Army, Coastal Engineering 
Research Center, Fort Belvoir, Virginia, Tech. Memo. 46, 155 pp. 



419 



ETUDES MICROBIOLOGIQUES ET MICROPHYTIQUES 
DANS LES SEDIMENTS DES MARAIS MARITIMES 
DE L'lLE GRANDE 
A LA SUITE DE LA POLLUTION PAR L* AMOCO CADIZ 

par 

Therese Le Carapion-Alsumard, Marie-Reine Plante-Cuny 
et Eveline Vacelet 



Station Marine d'Endoume et Centre d'Oceanographie 
13007 - Marseille, France. 



PRESENTATION SOMMAIRE DES BIOTOPES ET STATIONS ETUDIES 

Trois des biotopes caracteris tiques des raarais maritimes - schorres, 
chenaux de schorre, et haute-slikke - ont ete retenus pour cette etude 
dans deux sites, differant tres nettement quant a 1' importance de la pol- 
lution par le petrole de l'Amoco Cadiz (Fig. 1A - site Sud, Sud-Ouest tres 
pollue ; site Est, Nord-Est peu pollue). 

Le bloc diagramme (Fig. IB) roontre la difference de niveau altitu- 
dinal entre les 3 biotopes, entrainant evidemraent des differences de dur6e 
d' immersion. 



Les Schorres 

Les schorres de l'lle Grande sont des pres-sales a Juncus maritimus 
et Halimionc portulacoi.de s qui presentent une surface plus ou moins tabu- 
laire et un reseau de drainage variable (Fig. 1A, schorre Dl mieux drain^ 
que le schorre Al). 

Les deux stations de reference pour le "biotope schorre" sont Bl et 
CI (site Est, Nord-Est, Fig. 1A) faiblement atteintes par la pollution du 
fait de la mise en place d'un barrage de protection sous le pont reliant 
l'lle Grande a la terre. 

Les schorres tres pollues, Al et Dl , sont done situes dans la par- 
tie Sud, Sud-Ouest. Cette partie du marais servit pendant un certain temps 
de zone de stockage d'hydrocarbures issus du nettoyage des plages et ro- 
chers. 



421 



Les Chcn.iux 

Ccs scliorres sont draines par des chenaux presque constamment immer- 
gcs, dont le sediment est une vase fluide (station de reference C2 ; sta- 
tion tres polluee A2 - Fig. 1A et B) . 

Le Biotope Haute-Slikke 

Le biotope de vase sableuse intertidale ou haute-slikke, de part 
et d'autre du chenal central, a ete etudie en A3 pour le site pollue et 
on B3 pour le site peu pollue. Cette derniere station fut remplacee a par- 
tir de mars 1980 par E3 (meme type de biotope) lorsque les travaux de sur- 
cri'iiscmcnt du cbenal central eliminerent la station B. 



FIGURE 1 
(OPPOSITE) 

A - Schema de localisation des stations 



Stations de reference = C , B ]f schorres 
(Est, Nord-Est du pont) C 2 , chenal 

B_, E , haute-slikke 



Stations tres polluees = A , D , schorres 
(Sud, Sud-Ouest du pont) A , chenal 

A-, haute-slikke 



B - Bloc diagramme representant les 3 types de biotopes et le niveau 
des hautes-mers. 



422 



A 




SWIRLING SITES 

Reference stations = CI. Bl schorres (salt meadows) 
C2 tidal creek 
B3, E3 5LIKKE (mud slope) 

Polluted stations = Al. Dl schorres (salt meadows) 
A2 tidal creek 
A3 slikke (hud slope) 



B 




HMMME 
NTHWL 



Lhaute-slikke — 

higher mud slope 



schorre - 

salt meadow 



423 



ETUDES REALISEES DANS CES BIOTOPES ET METHODES UTILISEES 

Neuf missions d'echantillonnage pour 1' etude des hydrocarbures et 
des peuplements bacteriens et microphytiques ont ete realisees entre de- 
cembre 1978 et novembre 1980 (une derniere mission est programmee en no- 
vembre 1981, ce qui donnera un "suivi" de 4 ans) . 

Divers parametres physiques et chimiques (temperatures, salinites, 
pH, Eh) ont ete mesures dans l'eau et les sediments. 



Les Hydrocarbures 

Les hydrocarbures (HC) ont ete doses et leur composition analysee 
dans des fractions de carottes a differents niveaux (Tab. 1, 2, 3). 

Les concentrations en hydrocarbures totaux (HCT) exprimees en g. 
kg~l de sediment sec sont definies comme etant la fraction FA apres les 
traitements suivants appliques aux echantillons de sediments : 

- extraction de la matiere organique au toluene-methanol sur echan- 
tillon humide (Farrington et Tripp, 1975). 

- elimination du soufre (pesee avant saponification — > poids AV- 
SP). 

- saponification a la potasse (pesee apres saponification >• poids 

AP-SP). 

- fractionnement du produit de la saponification par la methode 
dite au "Sep-pak"(micro-colonne de silice a compression radiale) 
(Giusti et al., 1979) . 

- elution par trois solvants successifs : 
1° hexane fraction FA = HCT 

2° chloroforme fraction FB = fraction polaire 
3° methanol fraction FC 

L'extrait a 1 'hexane (FA = HCT) est ensuite analyse en chromatogra- 
phic liquide haute pression (HPLC reverse-phase) puis en chromatographie 
gazeuse capillaire (CPG) et infra-rouge lorsque la concentration est suf- 
fisante. Une analyse plus fine par spectrometrie de masse couplee avec la 
CPG est effectuee si necessaire. 



Etude Bacterienne 

Pour l'etude bacterienne, 1 'echantillonnage des sediments etait 
effectue par carottages. 

Les fractions etudiees etaient : 
dans les schorres (carotte de 60 cm environ) 

- couche de surface (su) 

- rhizosphere (rh) 

- couches plus profondes (couche argileuse : ca ; couche sableuse : 
cs) ; 



424 



dans les chenaux (carottes de 30 a 40 cm) 

- couche de surface (su) 

- zone reduite (zr) 

- couches plus profondes (ca ou cs) ; 
dans les slikkes (carottes de 10 a 40 cm) 

- memes couches que les chenaux. 

L' etude bacterienne de sous-echantillons comprenait : 

- denombrement de la microflore heterotrophe par MPN sur eau de mer pep- 
tonee a 5 g.l - ' ; 

- estimation de l'activite bacterienne sur les memes ensemencements ; 
etablissement d'une courbe d'activite qui depend de la presence de sou- 
ches a croissance rapide ; 

- denombrement des germes capables de degrader les hydrocarbures par MPN 
sur milieu mineral contenant du petrole "Arabian light" comme source de 
carbone ; 

- enzymologie : mise en evidence des differentes hydrolases presentes et 
estimation comparative de leur activite par la methode APIZYM. 

A la surface des carottes, l'activite enzymatique est due a l'ensem- 
ble du peuplement "bacteries + microphytes". Dans les couches plus profon- 
des, seule intervient l'activite bacterienne. 



Les peuplements microphytiques 

Les peuplements microphytiques etaient Studies sur des carottes 
plus courtes (3 premiers centimetres d'epaisseur) . 

Aspect Quantitatif 

L' aspect quantitatif du peuplement est essentiellement apprehende 
par 1' estimation d'un indice chlorophyllien de biomasse que nous abrege- 
rons en ICB : extraction a 1' acetone et mesures (avant et apres acidifi- 
cation des extraits) des concentrations en chlorophylle a (Chla ou ICB) 
et en produits de degradation de la chlorophylle (pheopigments = Pheo.), 
methode de Lorenzen (1967) modifiee par Plante-Cuny (1974) pour les sediments 
Resultats exprimes eniug.g - ! de sediment sec. 

Rapport Chla/Chla + Pheo : indice de vitalite des peuplements s'il y a 
preponderance de la chlorophylle (rapport ^ 0,5). 

i 
Aspect Qualitatif 

L' aspect qualitatif du peuplement consiste en une etude ecotaxino- 
mique des principales especes de diatomees et cyanophycees presentes. 

Note 

II est evident que dans la presente synthese tous les resultats 
obtenus dans les etudes microbiologiques et microphytiques n'ont pu etre 
pris en compte. lis feront l'objet de rapports separes. 

(Voir aussi Vacelet et al . , et Plante-Cuny et al . , 1981). 



425 



SYNTHESE DES PRINCIPALS RESULTATS 

Les resultats concernant 1' analyse fine des hydrocarbures et de 
leur eventuelle degradation font l'objet d'un rapport separe x . 

Des resultats succints seront donnes ici seulement pour servir a 
1' interpretation des phenomenes biologiques. 



Differents Degres de Pollution au Debut des Observations 

II faut noter ici 1' absence de "point zero" concernant l'etat des 
marais de l'lle Grande avant l'echouage de l'Amoco Cadiz en mars 1978. 
Aucune etude prealable n'existait sur ce site et il nous a ete impossible 
de trouver dans une region avoisinante un marais maritime de merae type, 
indemne, pouvant servir de reference. 

De sorte que, les stations choisies presentent en fait differents 
degres de pollution en decembre 1978, au debut de nos observations (HCT 
en surface, exprimes en g. kg - ' de sediment sec). 

Les valeurs ci-dessous, et notamment celles de Al et Dl, sont tres 
elevees en comparaison des valeurs donnees par Marchand (1981) pour des 
sediments profonds (15 a 100 metres) a la suite du naufrage du "Bohlen". 
Rappelons que le site de l'lle Grande etait un lieu de stockage des hy- 
drocarbures apres nettoyage d'autres sites. 

- schorres encore couverts de mazout en decembre 1978 : 

Al : 32,97 ; Dl : 94,68 

- schorre avec traces de pollution : 

CI : 4,17 

- schorre apparemment indemne : 

Bl : 1,9 

- chenaux drainant les schorres : 

tres pollue, A2 : 7,69 * 
apparemment indemne, C2 : 3,26 

- haute-slikke bordant le chenal central : 

visiblement tres polluee, A3 : 5,56 * 
apparemment indemne, B3 : 0,50 

Les concentrations evaluees en A2 et A3 (*) ont ete mesurees sur 
des echantillons provenant de 1' extreme pellicule superf icielle du sedi- 
ment (moins de 1 cm d'epaisseur) deja colonisee par des microphyte's. 



Evolution des Concentrations en Hydrocarbures et des Peuplements 
Bacteriens et Microphytiques a Partir de Decembre 1978 

Dans chacun des 3 biotopes - schorres, chenaux et slikkes - seront 
faites des comparaisons entre les stations tres polluees a differents 






x 



Etudes realisees par Henri Dou, Gerard Giusti et Gilbert Mille. 
Laboratoire de Chimie Organique A et LA 126 CNRS - Faculte des 
Sciences de Saint Jerome - 13397 Marseille cedex 13. 



426 



degres d'une part, et entre les stations tres polluees et les stations 
peu polluees d' autre part. 

On expose dans chaque cas : - 1' evolution des concentrations en HCT 
(g.kg~l), et de leur eventuelle degradation ; - l'evolution de l'activite 
bacterienne, du nombre de germes degradant les HC, de l'activite enzyma- 
tique ; - l'evolution quantitative et qualitative des peuplements micro- 
phytiques . 

Evolution dans les schorres 

Schorres tres pollues, Dl et Al . 

Schqrre_ Dl . 

En surface, la station Dl (Tab. 1) presente, presque deux ans apres 
l'echouage, la meme concentration en HCT (94,51) qu'en decembre 1978. II 
existe dans ce site des zones encore plus polluees (prelevement intention- 
nel dans une tache d'hydrocarbures en mai 1980 : 230,60). 

II semble y avoir, en ces points, une accumulation en surface par 
drainage du schorre environnant, lui-meme encore visiblement tres pollue 
en 1980. 

Le rapport AV/AP (Tab. 2), indicateur presume d'une biodegradation, 
augmente legerement en 1979 ainsi que l'activite bacterienne : un debut 
de degradation aurait eu lieu entre 1978 et 1979. On note parallelement 
une augmentation du nombre de germes degradant les HC jusqu'en novembre 
1979 (10^ a 10? germes. ml~l de sediment) suivi d'une regression en 1980 
(Fig. 2). 

L'activite enzymatique de 1' ensemble de la microflore a ete impor- 
tante en decembre 1978, s'est prolongee jusqu'en 1979 ce qui suggere la 
possibility d'un effet favorisant des HC. Cette activite regresse en 1980 
indiquant peut-etre un appauvrissement de la microflore bacterienne (re- 
gression de chymotrypsine, trypsine et hydrolases des glucides) (Fig. 5). 

Les microphytes (Fig. 8A,1>1 )totalement elimines et encore absents 
en novembre 1978, ont recolonise peu a peu la surface du sol et ont pre- 
sente un maximum non negligeable en juillet 1979 (50yug Chla.g - '). Ensui- 
te, la preponderance au printemps 80 des pheopigments indique un etat peu 
florissant de la population. Une reprise est amorcee en novembre 1980 
(40yUg Chla.g - '). II est possible que cette population vegetale comportant 
un fort pourcentage de cyanophycees reputees riches en hydrocarbures natu- 
rels en C'7 (Han et Calvin, 1969 ; Saliot, 1981) contribue a l'augmenta- 
tion observee du rapport cl7/Pr (Tab. 3) ce qui rend difficiles les inter- 
pretations quant a l'etat de degradation des HC. 

Dl : Dans la rhizosphere (cf. schemas des carottes, Tab. 1), on 
note dans le temps une diminution (de 8,13 a 0,23) de la quantite d'HCT 
et une augmentation du rapport AV/AP (1,20 a 2,06) pouvant indiquer une 
forte biodegradation. En effet, la concentration en germes degradant les 
HC croit de 10 2 a 10 6 germes. ml -1 jusqu'en 1980 (Fig. 2). Quant a l'acti- 
vite enzymatique, elle est fluctuante et plus faible en general en 1980 
(Fig. 5). 

427 



Dl : Dans les couches plus profondes (30 cm), les concentrations 
en HCT, faibles au depart (0,48) diminuent en 1979 (0,10). Le nombre des 
germes degradant les HC a cru jusqu'en avril 1980 puis a diminue (Fig. 2). 
L'activite enzymatique regresse depuis decembre 1978. Tous les groupes 
d'hydrolases sont concernes (Fig. 5). 

Sc_horre_ _A1 . 

En surface, contrairement au schorre precedent, ou persistent de 
fortes concentrations en HCT, les valeurs passent de 32,97 a 18,84 de 
1978 a 1979, raais la biodegradation parait peu importante (AV/AP C^c 1 ) . 
En 1980, la concentration tombe a 14,98. Les resultats concernant la rhi- 
zosphere en 1979 tendraient a prouver qu'il y a eu percolation. L'analyse 
montre en 1980, 1' absence d'alcanes lineaires et la persistance des HC 
satures ramifies et aromatiques. On observe egalement que la densite des 
germes degradants les HC augmente jusqu'en novembre 1979 et regresse en 
1980 (Fig. 2), soit faute de substrat (alcanes lineaires), soit par sui- 
te d'un phenomene climatique general (voir Bl et CI). 

L'activite enzymatique en Al en surface, est comparable a celle de 
Dl (accroissement en 1979, regression en 1980) (Fig. 5). 

Les microphytes ont ete elimines sur le sol Al par l'arrivee du 
mazout et etaient encore absents en decembre 1978, comme en Dl (Fig. 8A) . 

Par contre, une tres legere colonisation seulement etait amorcee en 
1979, suivie d'une diminution en 1980 (quelques ug Chla.g ' seulement). 
Les pigments degrades sont dominants en toutes saisons, traduisant le 
peu de vitalite de la population (Chla/Chla + Pheo. : 0,2 en moyenne) . 

Al : Dans la rhizosphere du schorre Al, il y a augmentation de 
0,47 a 3,68 des concentrations en HCT indiquant probablement une perco- 
lation en 1979, accompagnee d'une degradation importante (AV/AP : 1,47 
et 1,26, Tab. 2). Ensuite, la pollution diminue en 1980. La microflore 
degradant les HC etait en densite maximale en 1979, puis a regresse for- 
tement en 1980, davantage qu'en surface (Fig. 2). 

L'activite enzymatique est en augmentation depuis 1978, la pollu- 
tion etant proportionnellement moins forte que dans le schorre Dl (Fig. 
5). 

Conclusion sur les schorres tres pollues. 

Ces deux biotopes, tres pollues au depart, ont reagi differemment 
puisque le plus pollue (Dl) n'est pas le moins recolonise par les micro- 
phytes. II faut sans doute y voir 1' influence benefique d'une plus forte 
humectation : Dl, mieux draine done plus souvent inonde, est plus rapi- 
dement recolonise du fait de l'apport de particules argileuses favorisant 
la fixation des microphytes. 

Dans les rhizospheres, la degradation parait se faire convenable- 
ment, meme en cas de percolation. 

C'est done a la surface des schorres les plus eleves (ou les plus 
souvent exondes) que se restaure le plus lentement le peuplement micro- 
biologique. 



428 



Schorres peu polities, CI et Bl ■ 

Scho_rre_ CI . 

En surface, sur le schorre CI, raoins pollue (4,17 en 1978) les con- 
centrations en HCT ont rapidement diminue (0,54 en 1980). Les germes de- 
gradant les HC sont restes en nombre stable (10^ a 10^ germes. ml~l de 
sediment (Fig. 2)). L'activite enzymatique a ete constamment elevee. La 
degradation semble done s'effectuer normalement (Fig. 5). 

Dans la rhizosphere, il y a forte diminution des HCT avec le temps 
et forte degradation (AV/AP = 1,25). Les germes degradant les HC se sont 
maintenus en nombre stable (10 a 10-^ germes .ml -1 ) . L'activite enzymatique 
a decru en 1980. 

Dans les couches les plus profondes, les concentrations en HCT sont 
tres faibles en 1980 (0,05) et l'activite enzymatique constante. 

Schorre _B] . 

En surface, le deuxieme schorre de reference, peu pollue (1,90 en 
decembre 1978) n'a pratiquement pas raontre de variations jusqu'en 1979 
(1,75). Le nombre de germes degradant les HC- et les indices de biodegra- 
dation (1,34) tendent a prouver qu'il y aurait eu forte degradation (Fig. 
2). 

Les HCT doses en 1979 n'ayant pas les caracteres d'HC degrades 
(C'7/p r = 4,43), nous emettons les hypotheses que de faibles apports chro- 
niques d'HC se produisent en cette station, ou plutot que les microphytes, 
tres abondants sur ce site, seraient responsables d'apports d'HC biogenes 
(Predominance d'imparite ^ 1). 

Contrairement aux faits observes sur les schorres tres pollues, les 
microphytes n'ont pas ete ici elimines au depart et ne paraissent pas af- 
fectes par une faible pollution, tout au moins en 1978 et 1979. Une densi- 
te maximale du peuplement est observee en juillet 1979 avec 130 jag Chla. 
g~l (Fig. 8A) et un rapport Chla/Chla + Pheo. de 0,75 indice de bon fonc- 
tionnement de la population. 

Tout au long de l'annee, et contrairement aux schorres pollues, cet 
indice est toujours superieur a 0,5. Le peuplement de cyanophycees et 
diatomees est toute l'annee bien diversifie et les especes caracteristi- 
ques des marais maritimes y sont presentes . 

En 1980, cependant, un ICB moyen de 50 ug Chla.g - ^ est plus faible 
que celui des annees precedentes, mais comparable a celui du schorre CI. 
On ne peut, dans ces deux stations, exclure 1' influence nefaste eventuelle 
d'un facteur climatique en 1980. 

Dans la rhizosphere Bl, l'activite bacterienne et l'activite enzy- 
matique ont ete importantes et les concentrations en HCT, faibles au de- 
part, ont diminue encore. 

Conclusions sur le biotope "schorre". 

Dans les stations tres polluees au depart : 

429 



1° Une depollution se produit peu a peu, sauf si de nouveaux apports 
par drainage (?) maintiennent des taux de concentrations eleves. 

2° La degradation des HC est toujours plus faible, en surface et 
dans la rhizosphere, que dans les schorres peu pollues. Cette degradation 
est, dans les sites peu humectes, pratiquement stoppee. 

3° Les concentrations en germes degradant les HC sont toujours supe- 
rieures de 1 a 2 ordres de grandeur a celles des schorres peu pollues. 

4° Par contre, l'activite enzymatique est 2 a 3 fois plus faible 
que dans les schorres peu pollues. 

5° Apres avoir totalement disparu, les microphytes recolonisent 
tres lentement les schorres "asphaltes", un peu plus rapidement les schor- 
res pollues mais plus humectes. Par contraste, les schorres peu pollues 
sont tres florissants (ICB 10 a 20 fois superieur) . 

Evolution dans les Chenaux 

Chenal tres pollue, A2 . 

En surface, les concentrations en HCT ont diminue de 10,78 a 2,57. 
Les indices adequats prouvent qu'une forte degradation a eu lieu. Les 
chromatogrammes des HC restant en 1980 ne presentent plus les pics des 
alcanes lineaires. La degradation rapide parait terminee et les autres 
fractions resteront probablement en l'etat. Les germes degradant les HC 
ont augmente en nombre jusqu'en 1979 (10^) puis ont decru en 1980 (10^ 
germes. ml - ', Fig. 3), ce qui corrobore l'hypothese precedente de la non 
poursuite de la degradation mais n'exclut pas l'hypothese du facteur cli- 
matique. 

L'activite enzymatique est plus faible que dans la station non 
polluee (Fig. 6). 

Les microphytes ont recolonise tres rapidement la surface de la 
vase et ont atteint en novembre 1980, un maximum de 588 /ig Chla.g -1 , 
maximum absolu dans toutes les stations etudiees (Fig. 8B) . 

En 1978, cette microflore etait paucispecif ique (Phormidium et 
Amphiprora alata) . En 1980, la diversite specif ique d'une vase normale 
equivalente (Carter, 1933) est retrouvee. Pourtant un raclage effectue 
en mai 1980 montre encore une concentration d'HC de 14,20 g.kg~l. Les 
chromatogrammes montrent l'absence totale d' alcanes lineaires (Tab. 3). 

Dans la zone reduite (Tab. 1 : zr) , les concentrations en HCT 
ayant augmente jusqu'en 1980, on peut evoquer la possibility d'une perco- 
lation. A ce meme niveau, en 1980, tous les alcanes lineaires sont degra- 
des. La concentration mesuree concerne done des HC plus resistants. On 
observe en outre que le nombre de germes degradant les HC decroit forte- 
ment (10 germes .ml - ' ) . L'activite enzymatique decroit egalement. 

Chenal peu pollue, C2. 



En surface, les concentrations en HCT sont passees de 3,26 a 0,70. 
La biodegradation est importante (AV/AP eleve) . Le nombre de germes degra- 
dant les HC est stable (10 3 a 10^ germes .ml" 1 ) . 



430 



L'activite enzymatique dans cette station "propre" est aussi impor- 
tante que dans les schorres peu polities. Elle est en nette augmentation en 
1980, ce qui est peut-etre a relier aux travaux d'amenagement effectues a 
cet endroit (voir ci-dessous) . 

Les microphytes ont manifeste un maximum de developpement en ete 
1979 suivi d'une decroissance. Les variations saisonnieres paraissent 
done tres differentes dans les deux stations de type "chenaux", mais le 
chenal ou se trouve la station C2 a ete obture momentanement, en mai 80, 
par des travaux de surcreusement du chenal central. La composition des 
peuplements de microphytes a ete nettement perturbee et s'est appauvrie 
en especes et en individus. 

La zone reduite et la couche sableuse sous-jacente sont fortement 
depolluees (0,09 et 0,05). Le norabre de germes degradant les HC est sta- 
ble. Dans la zone reduite, une diminution de l'activite enzymatique se 
poursuit depuis decembre 1978, indice possible de la restauration d'un 
etat d'origine (disparition des lipases, augmentation des activites este- 
rases, aminopeptidases, chymotripsines et glucidases). 

Conclusions sur le biotope "chenal de schorre". 

1° Dans le cas de pollution forte, la biodegradation, apres avoir 
ete active, s'est ralentie ou arretee. Les HC encore presents ont peu de 
chances d'etre degrades rapidement. Dans le cas de pollution faible, la 
degradation a ete presque complete. 

2° Parallelement, le nombre de germes degradant les HC a augmente 
puis diminue dans le cas de forte pollution. II est stable ailleurs. 

3° L'activite enzymatique est moins importante, en surface, en cas 
de pollution. Elle est toujours plus faible en zone reduite. 

4° Les microphytes se developpent en surface de facon luxuriante 
dans les chenaux pollues. Les concentrations en Chla sont en 1980 nette- 
ment superieures a celles du chenal non pollue. 

Evolution dans les slikkes 

S likke tres polluee, A3. 

En surface, a l'endroit precis ou nous avons situe la station A3, 
on peut dire que les concentrations en HCT sont passees dans la pelli- 
cule superf icielle (ps = quelques millimetres d'epaisseur) de 5,56 a 0,27 
g.kg-1 entre decembre 1978 et mai 1980 (Tab. 1). 

Dans la couche sous-jacente (su : 2 a 3 cm d'epaisseur) les concen- 
trations sont passees de 24,95 a 0,60 entre 1979 et 1980. II y a done eu 
depollution en surface. Dans le raeme temps, les indices de biodegradation 
ont augmente jusqu'en 1979 (Tab. 2) et le nombre de germes degradant les 
HC egalement (Fig. 4) . 

Dans la couche sableuse, par contre, les concentrations en HC ont 
augmente de 0,65 a 2,40 en 1979, puis diminue en 1980 (0,50). Les indi- 
ces de biodegradation sont faibles. L'activite enzymatique est reduite 
(Fig. 7). II semble y avoir eu percolation, surtout en novembre 1979. 



431 



Devant les difficulties d' interpretation des resultats dans un tel 
biotope (problemes d' echantillonnages) , des prelevements par raclages ont 
ete faits en mai 1980. lis ont permis d'effectuer des dosages a partir d' 
un materiel abondant et de dif ferencier, d'une part la pellicule superfi- 
cielle constitute essentiellement de particules argileuses compactees par 
les microphytes, et, d'autre part, la couche sableuse visiblement encore 
tres polluee. 

Les resultats sont eloquents : 0,27 dans le premier cas, 15 g.kg~l 
dans le second. Ce sont des hydrocarbures d'origine "Arabian light" dont 
les alcanes lineaires certes sont degrades, mais dont les autres consti- 
tuents sont toujours presents /Tab ■4,'b)- 

Notre premiere hypothese du "piegeage" du petrole sous la matte 
vegetale se trouve confirmee. 

En effet, les filaments de cyanophycees et les diatomees compactant 
les particules argileuses avaient tres rapidement colonise ces vases im- 
pregnees d'HC puisqu'en decembre 1978, on observait un ICB de 140 ^ig Chla. 
g~l (Fig. 8C) , et tres peu de pheopigments (rapport Chla/Chla + Pheo. de 
0,96 , le plus eleve de cette etude) indiquant une population jeune. Ce 
peuplement se revelait paucispecif ique (Phormidiwn, deux especes de Nitz- 
sohia 3 Amphipleura, Rhopalodia) mais se diversifiait tres rapidement. Les 
deux cycles annuels de 1979 et 1980 presentent tous deux un maximum en 
automne ou en hiver, tout comme la vase du chenal pollue, avec des ICB 
presque aussi eleves et toujours tres peu de pheopigments. 

En 1980, le peuplement est tres riche et tres diversifie (presence 
de nombreuses especes caracteristiques de ces milieux) . 

La matte algale recouvre done un sediment dans lequel une depollu- 
tion a eu lieu, tout au moins dans la partie superf icielle, mais dont la 
couche sableuse est toujours irapregnee d'HC dont la degradation parait 
tres ralentie. Cette matte semble toujours jouer un role de frein a une 
depollution mecanique par le jeu des marees . 

Slikkes peu polluees, B3 et E3. 



La station B3 nous a paru devoir etre remplacee, en mars 1980, par 
une nouvelle station de reference (E3) , la slikke centrale ayant ete per- 
turbee par 1' obturation momentanee du pont, apres l'echouage du Tanio 
(mars 1980) puis par des travaux d'amenagement . 

Les concentrations en HCT dans ces stations sont faibles. La bio- 
degradation a ete importante. Le nombre de germes degradant les HC est 
stable (Fig. 4) . L'activite enzymatique de surface est en augmentation 
en 1980 (Fig. 7). 

Le peuplement microphytique est florissant, particulierement en E3, 
ou un indice C 17 /Pr de 4,47 en mai 1980 pourrait traduire, comme dans les 
schorres non pollues Bl et CI, la presence d'un hydrocarbure biogene par- 
ticulierement abondant chez certaines cyanophycees (Fig. 8C) . 

Contrairement a la slikke polluee, les couches sous-jacentes ici ne 
renferment pas d' hydrocarbures . 

432 



Conclusions sur le biotope "slikke" . 

Ces conclusions sont tres voisines de celles qui concernent les 
chenaux : 

1° En cas de pollution grave, la biodegradation, active d'abord, 
s'est ralentie ou meme arretee. 

2° Le nombre de germes degradant les HC a diminue depuis 1978. Dans 
les stations peu polluees il est stable. 

3° L'activite enzymatique parait toujours freinee en surface en cas 
de pollution forte. 

4° Les microphytes se sont developpes rapidement sur les sediments 
pollues, piegeant des particules argileuses et constituant une "matte al- 
gale" plus compacte que dans les chenaux, pellicule qui freine la depollu- 
tion de ces sediments. 



433 



CONCLUSIONS 



Nous avons essaye au cours de cette etude de nous attacher a compren- 
dre les interrelations qui pouvaient exister entre l'etat de degradation 
des hydrocarbures et 1' evolution des peuplements bacteriens et microphy- 
tiques des marais maritimes. La complexite de ces milieux et les problemes 
d'echantillonnage qui en decoulent rendent parfois difficile la comprehen- 
sion du f onctionnement d'un tel ecosysteme perturbe. 



En ce qui concerne l'ensemble des biotopes. 

1° 11 apparait tout d'abord que les marais maritimes de l'lle Grande 
restent tres pollues malgre une biodegradation importante. 

2° Les hydrocarbures presents actuellement a la surface des sediments 
ou dans des couches plus profondes (percolation ou "piegeage") sont a un 
stade tel (disparition totale des alcanes lineaires) que la degradation 
ne parait pas se poursuivre actuellement. Ce ralentissement peut avoir 
plusieurs causes : persistance des seules fractions les plus resistantes 
des HC, toxicite, pour le peuplement bacterien, de certains produits de de- 
gradation, facteur climatique defavorable a l'activite bacterienne. 

3° L'evolution de ces milieux s'est averee differente suivant le 
degre initial de pollution : 

- dans les stations tres polluees, les concentrations en germes de- 
gradant les hydrocarbures ont ete tres elevees. Puis leur nombre a decru 
en 1980. L'activite enzymatique a ete moins elevee en surface et dans les 
rhizospheres . 

- dans les stations peu polluees, 1' impact sur les peuplements micro- 
phytiques et bacteriens a ete peu perceptible, et la degradation a ete 
plus poussee, mettant en evidence l'existence probable d'un seuil de con- 
centration en HC en-dessous duquel la "restauration" est possible. 

En ce qui concerne chaque biotope en particulier, le deversement 
massif du petrole "Arabian light" n'a pas eu les memes consequences dans 
les sols du pre-sale, le plus souvent exonde (schorres) que dans les se- 
diments fins, le plus souvent immerges (chenaux et slikk.es). L' aspect mi- 
crobiologique et 1' aspect mecanique sont a prendre en compte dans les 
differences de depollution. 



Les vases intertidales 

Elles ont ete probablement plus vite nettoyees par le jeu des marees 
que la surface des schorres. Mais, par ailleurs, elles ont ete tres rapi- 
dement recolonisees du fait de l'apport de particules argileuses favori- 
sant 1' installation d'un peuplement paucispecif ique de cyanophycees et de 
diatomees qui, par la suite, s'est diversifie. Le mazout restant s'est 
trouve ainsi plus ou moins piege sous cette "croute" algale et pourrait 
s'y maintenir longtemps . 

434 



Les schorres 

Les schorres, par contre, ont ete moins rapidement depollues par 
les marees, certains presentant meme des zones d 1 accumulation. Apres 
avoir totalement disparu, les microphytes recolonisent tres lentement les 
sols, d'autant plus lentement qu'ils sont moins souvent immerges . La colo- 
nisation est actuellement environ 10 fois inferieure a la normale sur le 
sol des schorres a Juncus, observation qui concorde avec les resultats 
obtenus par Levasseur et Seneca sur la flore macrophytique (voir contri- 
butions de ces auteurs) . 



435 



TAULKAU 4 



EV0UT10N DtS CONCENTRATIONS FN IIVCROCARJtUKES TOTAUX I)AKS LES SEDIMENTS 
DES HAKAIS MAk HIKES DE L'lI.E CRA1JDE . 



Eiotcpcs 


D 


f { orcnlj 


HC 


totaux 


B-ke" 1 


dc ccdirocnt 


tec 


(t 


u i vt aux 












Stations 


dui.s la 


IC 1 


IC ? 


,C 6 


5/80 




carotte 


12/78 


3/79 


11/79 


Schorrc 




















tj 


32,97 






18,84 


14,98 


A . 




th 
ca 


0.4? 






3,68 


0,03 
0.04 






iU 


94,68 






94.51 


230.60* 


", 




rh 


8.13 






0.73 


17.78* 






ca 


0,48 






0,10 


O.I6» 


B . 




th 


1.90 
0.17 






1.75 
0,10 








(U 


«.U 






0,43 


0,54 


c . 




rh 

e«(1t-32 cd) 


0,26 






0.03 


0.15 
0,05 


CHcnfttjx 




ft 


7,89 








14,20 






•u 




10 


78 


6,59 


7.57 


A ? 




ir 


0,48 





22 


0,29 


1.14 






ca 


0, 10 






0,03 


0,08 






- 28-36 (a 










0,08 






[u 


3.76 






1.41 


0,70 


C 2 




c t 


0,77 
0,23 






0.09 
0,05 




llaau Sljfckc 




P* 


5.56 








0,27-15** 


A 3 




IU 




24 


95 


3,45 


0,60 






cs 




0,65 


2,40 


0,50 






cu 










0,89 


S 




ir 
ca 

su 








0,52 


0,08 
0,03 

0,56 


B 3 




/r 








0.19 


0.72 


i 




ca 










0,16 



ill t 

i 



rh 



i, 1 



'»! 

if : 
ti 



i 



rh 



tu l 
i 



rh 



(I I 



ts J 

i 

?r I 
1 

I 

is 



K \ 



n d ' en i/l uiii» r 1 \ ; ui •.!. 
** Rem i .'■.,.. • oni «' I < : i*f fc*i luo* dan* 1c cln 



* Cellr v- ■• 
d'hydrc.. 



i *1 Ir i," j ;■: 

uLurcw .ii ii 



..I i.-.i i *» dan* b»p CAclte 
i;*.'[ > ,r..d.u i»>n. 

nj] central . 



i 

i D j r m 

T 

ps : pclliculc suporf icicllc, prtMcvcrccnC par i .■». 1 .(•> 

iu : pjit ic uupci'f iciollr, quvlqucs cent irti'i re t» 

rli : rlti^OKpn^ro 

es : roue he s.iM eusc 

icr : r.owc reJu i t v 

ca : t puclw ar*.' i 1 eusc 



436 



TABLEAU 2 



IIYDROfARUUKES DANS l.LS SEDIMENTS UES MAKAIS MAR1TIMES DE L'lLE CRANDE 
(POLLUTION ]'AR L' AMOCO CADIZ) 



ANALYSE CII1MIQUE 



stations 


Poids r 

del 

fchant i 

t 


ucoide 
1 Ions 


AV-SP 
E*E~ 




AT 

fi- 


-SP 




AV/AP 


FB 

. -1 
g. kg 


Hydioca 
totaux 
B- kg' 1 


rbures 
(FA) 




IC, 


IC 6 


1C, 


IC 6 


le. 


1C 6 


IG, 


,C 6 


IC, 


1C 6 


IC, 


,G 6 




12/73 


11/79 


12/78 


11/79 


12/78 


11/79 


12/78 


11/79 


12/78 


11/79 


12/78 


11/79 


Schorre 


























Al 6U 


13.40 


25,10 


73,60 


43,48 


67,60 


39,58 


1.09 


1,10 


35,70 


16,93 


32,97 


18,84 


rli 


66,70 


99,50 


2,00 


8.92 


1,37 


7,10 


1,47 


1,26 


0,90 


2,99 


0,47 


3,68 


6U 


12,55 


14,60 


173,90 


243,45 


162,50 


210,50 


1,07 


1,15 


67,90 


102,12 


94,68 


94,51 


Dl rh 


59,15 


90,10 


19,78 


1,98 


16,50 


0,96 


1,20 


2,06 


8,40 


0,46 


8,13 


0,23 


CJ 


24,25 


74,80 


1,89 


0,24 


1,48 


0,19 


1.26 


1.26 


1,00 


0,06 


0,48 


0, 10 


Bl B " 


13,30 


10,85 


8,00 


10,29 


5.15 


8,98 


1,34 


1,14 


4,00 


5,56 


1,90 


1,75 


rh 


53.50 


97,80 


2,12 


1,99 


1,30 


0,89 


1.63 


2,24 


1.06 


0,58 


0,17 


0, 10 


CI su 


15,35 


19,85 


13.74 


2,43 


12,27 


1,93 


1.12 


1,26 


8,10 


1 , 19 


4,17 


0,43 


rh 


58,80 


132,50 


2,41 


0,15 


1,59 


0,12 


1,52 


1,25 


1,33 


0,05 


0,26 


0,03 


Oienaux de 
schorre 


























PS 


51,20 


6,10 


18,52 


21,49 


16,70 


12,41 


1,11 


1,73 


9,00 


4,25 


7,69 « 


6,59 


A? zr 


83.50 


120,60 


1,78 


0.95 


1,42 


0,60 


1,25 


1,58 


0,91 


0.23 


0,48 


0,29 


ca 


23,10 


139,20 


0,63 


0,17 


0,31 


0,07 


2,03 


2,43 


0,21 


0,02 


0, 10 


0,03 


EU 


10.50 


15,90 


14,07 


6,32 


8,27 


4,28 


1,70 


1 ,48 


5,00 


2,17 


3.26 


1,41 


C z zr 


39,80 


41,20 


3,07 


1,89 


2,26 


0,94 


1,36 


2,01 


1,50 


0,66 


0.77 


0,09 


cs 


18,65 


76,90 


0,60 


0,92 


0,45 


0,40 


1,33 


2,3 


0,22 


0,25 


0,23 


0,05 


Haul c- si ikkc 


























A PS 
A 3 

cs 


37, eo 


1,05 


11,48 


16,91 


1 1,44 


12,91 


1,00 


1,31 


5,88 


8 


5,56« 


3,45 




106.50 




7,43 




6,66 




1,12 




3,54 




2,40 


n P 3 
B 3 

cs 




7,50 




6,18 




2,66 




2.32 




1,34 




0,52 




112, 30 




3,43 




1,76 




1,95 




1,14 




0, 19 


Arabian 
light 






100 c 




9', f. 




1,07 




32X 




68% 





AV-SP : avJint Riiponi fi ration 

AP-5)' : ajirrii hflpnnif . rat jnn 

jmj3<I« en k p/ir V Y, ''*' Ti'.ljnint fcCC 

AV/AP : r/-;.jMirt 

111 : riAClion K t.r-^nu'i i.wr 5<\>~VaV , fOutlor. HC CI 3 

\h : fr.nii'.n A. M ut 3 m, \wr.n\\r : liy.lf it- ;n t.ni ■ i> \t*\u 

yn : |.r-M ImjIi- » i»|..tI h i-llc 

( t n ( mi. i ni r«i i • -t.K «.iit .'t<' r-v/ilu'cM nur ifrn 
■VUnl illrvtm <!. i..'i!iii,.n[ r*c)t* /. \n rpMnU 

fcur 1 »• | i r T n 1 n (M, S tin %)* ( ;,,, i (.n. n r « l.vi I (mi) , 



pnr t ii- liupcrf \r !<■] )«,. 
qiu-l(]tio« rrni imnl its. 
ill i ,'.i',j)ln'-ri' 
7011c ri'du i I v 
i.iuit'lw .irc.i 1 ciior 

IOllC.ll Hflbll 'H'" 



437 



TAMIJAU 3 






HYUKOCARilURES DAKS LKS SIMMI NTS DES HAHA1S MAKITIKES DE L'lLE CRANUE 
(.POLLUTION IAK L' AMOCO CADIZ) 



ANALYSE CIIKOMATOOKAI'IIIQUK DE U FRACTION SATUREt 







C J7 / Pr 






C, 8 / Ph 






Pr / Ph 




Prfdoro 


lnance d 


imparltS 


Stations 


IG 1 


IG 6 


IC 8 


1G . 


IG 6 


IG e 


IG . 


IG 6 


IG 8 


IG 1 


IG 6 


IG 8 




12/78 


11/79 


5/80 


12/78 


1 1/79 


5/80 


12/78 


11/79 


5/80 


12/78 


11/79 


5/80 


Schor re 


























A BU 

1 

rh 


1 

0.48 


0,5 

o,5 


XX 
12 


0,77 
0,41 


0,58 

0.21 


XX 
4.5 


0,54 
0,61 


0.67 
0,35 


XX 
0.25 


= 1 


XX 
XX 


XX 
1,30 


BU 


0.60 


0,2 


1,88 


0,47 


0,11 


1 ,21 


0.60 


0,54 


0,67 


^1 


XX 


0,91 


D rh 


1,24 


1.5 


2.14 


0.93 


".92 


1 ,40 


0,75 


0,66 


0,64 


»1 


1 ,40 


1 


ca 


3,30 


2 


3 


0,78 


1,92 


2,38 


0,17 


0,83 


0,61 


XX 


XX 


1 .12 


B '" 


XX 


4,43 




XX 


2.62 




XX 


0,54 




XX 


1.57 




1 rh 


0,21 


1.31 




1 ,75 


4 




7,80 


3.2 




2.37 


XX 




< Eu 




1,42 


6 




6.20 


4,64 




3.80 


0,55 




1,11 


1 .27 


' rh 




2,80 


6,82 




6.67 


7.23 




1,60 


0,85 




1,05 


1 ,84 


Clicns-ix rfo 


























schorrc 


























ps 




0.35 


XX 




0,13 


XX 




0.56 


XX 




XX 


XX 


A- zr 




0,50 






0,26 






0.58 






1.25 




ca 




1,00 


2,83 




3,50 


2,89 




2,20 


0,67 




1.03 


1.17 


su 


0.13 


0,19 


XX 


0.39 


0,44 


XX 


3,50 


23,33 


XX 


0,99 


1 .84 


XX 


C 2 *r 


0,13 


1,25 




0,26 


J. 5 




2,28 


4 




1,06 


1 ,48 




cs 


2.33 


3.33 




5,30 


3,5 




2 


0,75 




0,89 


1,30 




Slikkc 

A S " 
*3 

cs 




4,10 
0,09 


XX 
XX 




C.OO 
< 0,06 


XX 




1.25 
<0,85 


XX 
XX 




1,03 
XX 


XX 
XX 


B PS 




0.53 


XX 




0,53 


1 ,42 




0,94 






1.04 


1 ,77 


3 

cs 




0,29 






0.14 






4,72 






1,60 




E 
J 

ca 






14,47 






1,18 






0,5 






1.19 






XX 






6,5 






XX 






2,36 


Arjbi an 
light 


10,30 






4,70 






0,48 






0,88 







YtC d'T.i nflnco d* ifupar ) t c 



2 <r 23 * C 2, * C 27> 



XX 



Irn rlir m«m oj;rnwnti*n lie nioiitrmt p)u<. )n pii'i.n.r d'/ilt 



I i nffll ri • . 



hu - |, i r i i . r ,i,.. i 1 i . i . 1 1 , : ijih-lt|ii>H i t-iti inn* trf'ii 

ill - rlii 7 ■ »;p!i« I i 

( r. - . rut- )..- b .1.) use VI * / ■ .;.. ■ I t'/' u j t t 

IT - plJMIIM ' rt m ' '■'>' I"- i'i ,- 1 I « m'io 

pi. - |.h> !/.•„. 438 



12-14 )uiH 79 



2-7 oct 79 



23-25 nov 79 

I 1 • T 



1-2 avrll 80 



19-20 mal 80 



nov 80 





Ci 



1 





FIGURE 2. Norabre de germes (log) degradant les hydrocarbures a differentes 
profondeurs dans les schorres tres pollues (Al et Dl) et moins 
pollues (Bl et CI) des marais niaritimes de l'lle Grande. 






i - . . 



coucbe d'hydrocarbure 
epuche a microphytes 
rhizosphere 



4% 



argile 

couche reduite 

sable 



439 



12-14 juia 79 



1-2 avril 60 



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24-25 nov 00 




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1 

1 




FIGURE 3. Nombre de germes (log) degradant les hydrocarbures a differentes 
profondeurs dans les chenaux tres pollues (A2) et moins pollues 
(B2) - meme legende que figure 2 -. 



12-14 Juill 79 



2-7 ocl 79 



1-2 avril 80 19-20 mal 80 24-25 nov 80 





B3 









FIGURE 4. Nombre de germes (log) degradant les hydrocarbures a differentes 
profondeurs dans les slikkes tres polluees (A3) et moins pollu- 
tes (B3) - meme legende que figure 2) -. 



440 



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FIGURE 8 



Evolution temporelle des concentrations en chlorophylle a (trait plein) 
et en pheopigments (pointilles) a la surface des sediments (en ug-g de 
sediment sec) . 



A - Stations de schorres B , C peu pollues 

D , A tres pollues 



B - Stations de chenaux C peu pollue 

A tres pollue 



C - Stations de slikkes B , E , peu polluees 

A tres polluee 



444 



A 



150 - 



Chi. a 
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100 - 



50- 




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447 



REFERENCES BIBLIOGRAPHIQUES 



Atlas, R.M. et A. Bronner, 1981, Microbial hydrocarbon degradation within 
the intertidal zones impacted by the Amoco Cadiz oil spillage : in 
Amoco Cadiz. Fates and effects of the oil spill. Proc. Internat. 
Symposium. C.O.B. Brest (France) novembre 19-22, 1979, pp. 251-256. 

Butler, J.N. and E.M. Levy, 1978, Long term fate of petroleum hydrocar- 
bons after spills. Compositional changes and microbial degradation : 
J. Fish. Res. Board Can., Vol. 35(5), pp. 604-605. 

Carter, N., 1933, A comparative study of the alga flora of two salt mar- 
shes : J. Ecol., Vol. 21, pp. 128-208, 385-403. 

Colwell, R.R., A.L. Mills, J.D. Walker, P. Garcia- Tello, et P.V. Campos, 
1978, Microbial ecology studies of the Metula spill in the straits 
of Magellan : J. Fish. Res. Board Can., Vol. 35(5), pp. 573-580. 

Ducreux, J., et M. Marchand, 1981, Evolution des hydrocarbures presents 
dans les sediments de l'Aber Wrac'h, d'avril 1978 a juin 1979 : in 
Amoco Cadiz. Fates and effects of the oil spill. Proc. Internat. 
Symposium. C.O.B. Brest (France) novembre 19-22, 1979, pp. 175-216. 

Farrington, J.W., and B.W. Tripp, 1975, A comparison of analysis methods 
for hydrocarbons in surface sediments : in T.M. Church (ed.), Marine 
Chemistry in the Coastal Environments, Amer. Chem. Soc. Symp. Series 
n° 18, Washington, D.C., pp. 267-284. 

Fujisawa, H., M. Murakami, et T. Manabe, 1977, Ecological studies on hy- 
drocarbons oxidizing bacteria in Japanese coastal waters. I. Some 
methods of enumeration of hydrocarbon oxidizing bacteria : Bull. 
Jap. Soc. Sc. Fish., Vol. 43(6), pp. 659-668. 

Fujisawa, H., M. Masatada et M. Takehiko, 1978, Ecological studies on hy- 
drocarbons oxidizing bacteria in the oil polluted areas caused by the 
Mizushima oil refinery accident (Seta Inland Sea) : Bull. Jap. Soc. 
Sc. Fish., Vol. 44(2), pp. 91-104. 

Giusti, G., E.J. Vincent, H.J.M. Dou, et R. Faure, 1979, Etude par RMN 

de la concentration et de la nature des hydrocarbures presents dans 
les sediments cotiers superficiels de l'lle des Embiez : La Vie 
Marine, 1, pp. 24-29. 

Han, J. and M. Calvin, 1969, Hydrocarbon distribution of algae and bacte- 
ria and microbiological activity in sediments : Proc. nat. Acad. Sci. 
U.S.A., Vol. 64(2), pp. 436-443. 

Lorenzen, C.J., 1967, Determination of chlorophyll and Pheo-pigments : 
Spectrophotometric equations : Limnol. Oceanogr., Vol. 12(2), pp. 
343-346. 



448 



Marchand, M. et J. Roucache, 1981, Criteres de pollution par hydrocarbu- 
res dans les sediments mar ins . Etude appliquee a la pollution du 
"Bohlen" : Oceanol. Acta, Vol. 4(2), pp. 171-183. 

Plante-Cuny, M.R., 1974, Evaluation par spectrophotometrie des teneurs en 
chlorophylle a fonctionnelle et en pheopigments des substrats meubles 
marins : Doc.~Sci. Mission ORSTOM, Nosy-Be, Vol. 45, pp. 1-76. 

Plante-Cuny, M.R., T. Le Campion-Alsumard, et E. Vacelet, 1980, Influence 
de la pollution due a 1' Amoco Cadiz sur les peuplements bacteriens 
et microphytiques des marais maritimes de l'lle Grande, 2, Peuple- 
ments microphytiques : i_n Amoco Cadiz. Fates and effects of the oil 
spill, Proc. Internat. Symposium, C.O.B., Brest (France) novembre 
19-22, 1979, pp. 429-442. 

Saliot, A., 1981, Natural hydrocarbons in sea water : in E.K. Duursma and 
R. Dawson (ed.), Marine Organic Chemistry, Amsterdam, pp. 327-374. 

Thompson, S. and G. Eglinton, 1979, The presence of pollutant hydrocarbons 
in estuarine epipelic diatom populations, II, Diatom slimes : Estua- 
rine and Coastal Marine Science, Vol. 8, pp. 75-86. 

Traxler, R.W., et J.H. Vandermeulen, 1981, Hydrocarbon -utilizing micro- 
bial potential in marsh, mudflat and sandy sediments from North 
Brittany : in Amoco Cadiz. Fates and effects of the oil spill. 
Proc. Internat. Symposium. C.O.B., Brest (France) november 19-22, 
1979, pp. 243-249. 

Vacelet, E., T. Le Campion-Alsumard, et M.R. Plante-Cuny, 1981, Influence 
de la pollution due a 1' Amoco Cadiz sur les peuplements bacteriens 
et microphytiques des marais maritimes de l'lle Grande, 1, Peuple- 
ments bacteriens : _in Amoco Cadiz. Fates and effects of the oil 
spill. Proc. Internat. Symposium. C.O.B., Brest (France) november 
19-22, 1979, pp. 415-428. 

Ward, D.M., 1981, Note de synthese. Microbial responses to Amoco Cadiz 

oil pollutants : in Amoco Cadiz. Fates and effects of the oil spill. 
Proc. Internat. Symposium. C.O.B., Brest (France) november 19-22, 
1979, pp. 217-222. 



449 



1964-1982, COMPARAISON QUANTITATIVE DES 

POPULATIONS BENTHIQUES DE ST-EFFLAM 
ET DE ST-MICHEL-EN GREVE AVANT, PENDANT 
ET DEPUIS LE NAUFRAGE DE L' AMOCO CAPIZ 



par 



C. CHASSE et A. GUENOLE-BOUDER 
Laboratoire d' Oceanographie Biologique, 



Institut d' Etudes Marines, 
Universite de Bretagne Occidentale, 6, avenue Le-Gorgeu, 29283 Brest cedex, France 



Resume 

La baie de Lannion, largement ouverte face a la progression des 
nappes de petrole de 1 'AMOCO CAPIZ, fut parti cul i erement souillee : 
60 millions de cadavres echoues furent denombres sur les deux 
plages du fond de la baie de St-Efflam et Locquemeau. 

Des etudes anterieures sur l'estran de St-Efflam, representati f 
des nombreuses plages de sable fin de Bretagne, ont servi de reference 
a ce tra vai 1 . 

L'impact du petrole est tres variable sur les diverses especes 
d'une meme station. La partie Est de la plage, plus contaminee, 
montre une plus forte mortalite. Le haut et le bas de l'estran sont 
plus affectes que la partie intermediate. Deux processus semblent 
intervenir : 

- les nappes d'echouages en haut, 

- le petrole dissout ou en emulsion dans la masse d'eau en 
bas et dans tout 1 ' i nf rati dal . 

A la mortalite immediate s'ajoutent des mortalites et des 
effets patho 1 ogi ques a long terme. Certaines especes continuent a 
regresser meme en 1981 et les recrutements souvent inexistant en 
1978 s'amorcent en 1980, pour certains timidement encore en 1981. 
L'Est de la plage reste fortement touche bien que des signes de 
recouvrance certains apparaissert sur le reste de la plage mais 
les gros peuplements du bas de la plage a Solcn, Eniii, lchinocan.dlu.rn, 
iu.tn.ania, h\actxa coniallina ne sont pas reapparus. 

451 



INTRODUCTION 

Les nappes d'emulsion petroliere de 1' AMOCO CADIZ poussees a la surface de la 
Manche, le long de la cote, par les vents d'Ouest ont ete freinees en se heurtant sur les 
saillants successifs du rivage. Quatre zones principales d'obstacles se sont dressees face 
a leur progression vers l'Est. Ce sont les roches et les ilots des abers et de la presqulle 
Ste-Marguente, d'abord ; le champ de roches de Hie de Batz, de Santec, de RoscolL 
ensuite ; puis les roches de Pnmel et du Guersit ; enfin, celles des rebords Est de la baie 
de Lannion avec Tile Grande. En chacun de ces lieux, et surtout dans les criques, les 
estuaires et les baies de sable fin les plus proches qui les precedent le petrole s'est abon- 
damment accumule en provoquant de lourdes mortalites donnant lieu a d'importants 
echouages de cadavres de poissons, d'oiseaux et de coquillages. 

La baie de Lannion, deja fortement souillee, en 1967, par le petrole du Torrey Canyon, 
a ete atteinte par les nappes de V AMOCO CADIZ des le 5 e jour apres le naufrage. Sur les 
deux grandes plages de sable fin du fond de la baie nous avons recense 60 millions d'indi- 
vidus morts. dont la moitie sur la Grande Greve (St-Efflam). Le cinquieme seulement des 
cadavres etait accumule dans le spectaculaire et nauseabond cordon d'echouage du niveau 
des hautes mers ; la fraction la plus importante, bien que plus discrete, etait eparpillee 
en nuages a la surface de 1'ensemble des plages. Par des transects de plages, realises avec 
des gabarits metalliques d'1/4 de m 2 , par 5 equipes d'etudiants operant durant 3 jours, 
nous avons obtenu le decompte suivant pour les principales especes : 



ESPECES 


Mb re d'individus 
(cadavres) 


Poids en matiere 
organique seche(C) 


Poids brut 
( t ) 


Eehinoaardiurr 

aordatum 


20. 10 6 


4 


260 


Cardium edule 


16. I0 6 


5 


70 


Mactra corcllina 


14. I0 6 


4 


50 


Pharus lejumen 


5.10 6 


10 


100 


Ensis siliqua 


1 . 10 6 


2,5 


25 


Lutraria lutraria 


0, 1 .106 


0,8 


10 


Donax vittatus 


1 . !0 6 


0,04 


0,6 


Tellina fabula 


0,03. 10 6 


0,001 


0,01 


Tellina tenuis 


0,02. 10 6 


0,001 


0,01 


SOMME 


57.15.I0 6 


25,366 


515,62 



A cette mortalite initiale. brutale, s'est ajoutee une importante mortalite ulteneure plus 
discrete. L'observation des phenomenes dans leur ensemble geographique ne nous a pas. 
permis de cerner cette mortalite durant les premiers mois. Deux campagnes trimestrielles. 
avec seulement 10 stations regulierement suivies a St-Efflam. ont pu etre effectuees. Ce 
n'est qu'en Janvier 1979. dans le cadre d'un contrat avec la NOOA. que nous avons pu 
mettre en place un reseau d'observations mensuelles mais qui ne couvrait 1'ensemble de 
la plage qu'en 6 mois. 

Les peuplements des plages de la Grande Greve (St-Michel et St-Efflam) et de Locque- 
meau ont ete etudies qualitativement depuis un siecle par les chercheurs et les etudiants 
de la station biolog'.que de RoscolT. Des etats de references quantitatifs. etablis sous forme 
de cartes d'isobiomasses, de 1965 a 1968 (C. Chasse, 1972), donnaient, pour la plage de 
St-Efflam. des points de comparaison utiles a la fois pour le suivi des principales especes 
et pour l'impact des hydrocarbures deja evalue lors du naufraae du Torrey Canyon. 
en 1967. 



452 




453 



L'ensemble de la nouvelle canographie des peuplements de la plage de St-Efflam a ete 
realise avec une centaine de stations quantitatives dont 65 ont ete etudiees d'une maniere 
plus approfondie. Chaque station a fait l'objet de 3 prelevements de sediment effectues 
a la benne a mam de 1 16 de m 2 sur 20 cm de profondeur. La faune est recueillie sur place 
par tamisage sous l'eau sur maille de 1 mm, elle est determinee. comptee et pesee. Des 
cartes d'isobiomasses des principals especes ont ete dressees, comparables aux cartes 
anteneures realisees avant et apres le naufrage du Torrey Canyon. 

Dix stations caracteristiques des pnncipaux peuplements. situees au bas et au centre 
de la plage, et suivies durant toutes les operations, ont permis d'etablir revolution des 
especes dans le temps. 



LE MILIEU 

Sur la cote Nord de Bretagne, s'ouvrant sur la baie de Lannion. face aux vents dominants 
de secteur Nord-Ouest, a quelque 20 km a l'Est de la baie de Morlaix, la « Lieue de Greve » 
est une vaste plage de 5 km 2 tapissee de sable fin de 100 a 130 u, emergeant presque entie- 
rement aux grandes basses mers. Elle est profondement encaissee entre des collines 
elevees. large de 2 km au niveau des basses mers, elle atteint 4 km au niveau des hautes 
mers, d'oii son nom de « Lieue de Greve ». II y a 1,6 km en moyenne entre ces deux niveaux. 
Une butte enorme. Roc'al haz, haute de 99 m. s'avance legerement en compartimentant 
faiblement le fond de la baie, separant les localites de St-Efflam, a l'Ouest, de St-Michel-en- 
Greve. a l'Est. Six ruisseaux issus des coteaux eleves qui bordent le fond de la baie coulent 
en convergeant, a basse mer, vers l'entree de la baie entre les pointes de Plestin. a l'Ouest 
et de Beg-an-Fourn, a l'Est. Les trois ruissellements de l'anse onentale sont les plus 
importants. Par Ieur action de dessalure ils sont responsables de l'appauvnssement 
considerable des peuplements des niveaux moyens de cette anse, liee. par ailleurs. a l'expo- 
sition maximale aux houles des vents dominants du secteur Nord-Ouest. L'anse occi- 
dental ne recoit que des apports d'eau douce tres limites (une legere salure estivale 
apparait). Elle est relativement abntee des vents de Nord-Ouest par la pointe de Plestin. 
et partiellement protegee des vents importants de Nord-Est par les pointes de Beg-an- 
Fourn. Locquemeau, et la cote Est de la baie de Lannion. Aussi, le sediment y est-il 
legerement plus fin, moins permeable et moins oxygene ; c'est la zone la plus ricliement 
peuplee. Elle presente un petit massif de roches metamorphiques noires, dures et tour- 
mentees : le « Rocher Rouge ». qui, a 1 km du fond de l'anse. couvre 1 ha et s'eleve depuis 
les basses mers moyennes jusqu'au niveau des pleines mers de vives-eaux. II offre un abn 
permettant le developpement de sediments legerement envases en arriere. Un maigre 
herbier de Zostera nana s'etend au niveau des basses mers de mortes-eaux ; il ne modifie 
que tres peu le sediment, la biomasse des Zostera y etant faibie (250 a 600 g frais au m 2 , 
moyenne 350). Notons son leger deplacement vers l'Ouest, depuis 1968. Le phenomene 
de sursalure estivale qui s'y produit, du a l'evaporation du film d'eau qui n'a pas le temps 
de s'ecouler durant la basse mer, est insuffisant pour modifier les peuplements. a moins 
que Ton puisse lui attribuer la presence tres clairsemee de quelques .Wereis dicersicolor. 

Un aspect important particulier a cette greve est 1'accumulation croissante, d'annee 
en annee, d'algues non fixees, d'ectocarpales brunes libres au niveau des basses mers, mais 
surtout d'L ka laauca verte au debut du printemps et a 1'automne. au-dessus du niveau 
de la mi-maree. Ces algues couvrent a basse mer. d'un revetement parfois continu. de 
tres larges etendues de sable ; elles sont animees d'un balancement pendulaire au gre des 
marees et des vents. Ces « marees vertes » proviennent de l'eutropmsation croissante de 
l'impluvium des bassins de drainage des ruisseaux par les nitrates, les phosphates, la 
potasse. les pesticides et les lisiers d'ongine agncole. Elles jouent un role trophique impor- 
tant notamment par la liberation des spores et gametes et par le support qu'elles consti- 
tuent pour une riche faune d'Harpacticoides, de Foraminiferes, de Cilies et d'Amphipodes 
[Dexarmne spinosa). Elles sont partiellement consommees par les Talitres des hauts 
niveaux. La destruction des Amphipodes par le petrole explique peut-etre partiellement la 
particuliere abondance des « marees vertes » de 1978 et 1979. 



454 



EFFETS DE LA MAREE NOIRE SUR LES PEUPLEMENTS SED I MENTAI RES 

Sur les cartes suivantes sont reportes 4 etats successifs cie 
distribution pour chaque espece : 1964-1968, 1979, 1980 puis 1981. 

Sur les cartes A, on lit les zones de forte densite des 
principales especes. Nous comparons 4 periodes, les especes sont 
representees par leurs initiales : 

Ba. : BatkypoA2A.a pilot* a, i>aA6i it guMULamAonniayia. 
{notiej> AeApzctivrnznt V, S) 

We : NeAinn cJJVuxXalxx^ 

Un. : LiAothoz bnzviconniA 

Aa. : AAznicola maAina 

Ow : OwaYiia. ftuAifco Amii> 

It : Tzttina tznaiA 

T£ : Ttltina. fabula. 

Vo : Vonax vittat.uA 

Opk •. AcAocnida bAackiata 

En&iA e.yu>ii> oX Evu>iA iiliqua. 

MactAa. coAattina 
PhcuiuA ligamzn 

lutACL'UjX lutAOAJjX 

Les especes etudiees reagissent de maniere differente comme 
en temoigne la courbe de 1 'evolution des biomasses et le tableau 
Notons qu'il s'agit la de l'evolution moyenne de 10 stations. 
Des depl acements des zones de peuplements visibles sur les cartes 
n'ont pas pu etre pris en compte dans le tableau. 

Les cartes B a presentent les courbes d'isovaleurs en 
cal/m des biomasses des principales especes de la macrofaune 
endogee. Les facteurs de conversion sont : 

1 cal = 1 g de matiere organique fraiche = 0,2 g de matiere 
organi que seche . 

Les populations de quelques especes n'ont apparemment pas 

ete touchees , elles paraissent meme s'etendre : par exemple, les 

deux polychetes errantes Nzphty* hombzAgii (Cartes B) et SigaZion 

mathildaz (Carte C) ce dernier ayant tendance a coloniser maintenant 

1 e haut de la pi are . 

455 



Le crabe Platyoni.cka6 latipei, (cartes D) dont les noyaux se 
decalent vers l'Ouest de la greve ou ils s'etendent en densite, et 
le bivalve Te.lli.na tenui.6 (carte E), qui apres une tres forte 
progression jusqu'en 1980, voit ses effectifs amorcer une diminution 
sur les noyaux Est et Ouest mais avec le maintien du noyau central 
f i xe . 

D'autres especes par contre ont beaucoup regresse apres la 
catastrophe . 

En opposition a T ell-ina tenui.6 , Telltna faabula (cartes F) qui 
occupait en 1968 tout le niveau de basse mer, continue a regresser 
dans les tres bas niveaux ou elle disparait actuel 1 ement a l'est. 

L'ophiure kcn.o cni.da bn.achi.ata (cartes G) est de moins en moins 
presente. On assiste a une diminution du nombre des noyaux plus 
etal es vers 1 ' Ouest . 

Les polychetes sedentaires An.zni.cola man.ina (cartes H) et 
Owenla ^ubl^ofimii, (carte I) ont regresse apres la maree noire, 
mais a partir de 1980 ; les deux especes se developpent a nouveau 
sur le cote Est de 1 ' Estran, bi en que pour Owen-la on constate une 
legere diminution en 1981. 

Le bivalve Vonax. vi.ttatu.6 preponderant en 1968, a probablement 
bien diminue avant 1978 puis a completement disparu apres 1' 
"AMOCOCADIZ" . Apres une timide reapparition en 1980, le noyau central 
prend de 1 'importance , s'etend vers le bas de la plage et le noyau 
de l'Est se consolide (carte J). 

En 1979 on trouve les Amphipodes Ba£hypoie.<La (carte K) et 
Ufiothoz (Carte L) en petite quantite juste au Nord-Ouest de la 
plage, ils ont beaucoup regresse apres la maree noire en 1980, 
ils n'ont pas recupere en biomasse mais se sont etendus. 

En 1981 une legere regression pour Ratnyponeia pourrait etre 
attribue a une mortalite estivale tandis qu ' Un.oth.oe se deplace 
vers le centre et non l'Ouest de la plage. 

Les cartes M representent des especes non cartographi ees 
auparavant il semblerait qu'elles aient pris de l'importance 
depuis 1968 : mais a partir de 1980, Magelona paplllic.on.nli, et 
Glycena convoluta voient leurs effectifs diminuer fortement 
surtout a l'Est de la plage. 

456 



En 1980, on a pu cartographi er Candium zdixlo. zt Mniim ciiAatulu^ 
qui avaient disparu apres la maree noire (carte N). lis sont 
actuel 1 ement en regression. 

Spiophane.6 bombyx apparu en 1980 s'etend vers le centre et le 
bas de la plage (cartes 0) 

Par contre les trois autres especes apparues en 1980 
?a>tado ne-c-6 afimata, Etzonz falava zt Capita men, tu.6 (cartes 0) ont 
beaucoup diminue en 1981. Notons que Capi.toma.6tu6 minima* est 
significatif d'un milieu pollue (LE M0AL Y.et QUI LLIEN-M0N0T , 1979 ) 

CONCLUSIONS 

1- PERTES VE BJ0MASSE VIFFEREES 

La contamination des organismes n'a pas toujours ete 
immedi atement mortelle. Dans les sediments restes longtemps 
contamines, certaines especes qui avaient bien survecues au 
printemps de la maree noire ont vu leurs populations s'effondrer 
en 6 mois, voire un an plus tard. Le tableau suivant, portant sur 
10 stations de sable fin du bas de la plage de St Efflam en baie 
de Lannion, milieu bien representati f par sa nature et par son 
degre de contamination, montre que le taux de survie ultime pour 
les especes qui avaient bien survecues est nettement plus faible 
que celui enregistre a la fin du printemps 1978 pris comme 
reference, soit apres la maree noire. 



ESPECES 


PRINTEMPS 1978 


ETE 1978 


1ER SEMESTRE 
1979 


2eme SEMESTRE 
1980 


1ER SEMESTRE 
1981 


TELLINA FABULA 
TELLINA TENUIS 
OWENIA FUSIFORMIS 
ARENICOLA MARINA 
NEPHTYS HOMBERGII 




0,20 
0,65 
0,75 
0,72 
2 


0,20 
1,39 
0,32 
1,67 
0,33 


0,035 

1 

0,34 

3,30 

0,42 


0,09 
0,88 
0,36 
3,11 
0,68 


BI0MASSE T0TALE 


1 


0,77 


1,18 


1,02 


0,95 



Le facteur mul ti pi i cati f est proche des valeurs ulterieures 
les plus faibles des dates variees rencontrees dans ce tableau soit 
0,09 ; 0,6 5 ; 0,3 2 ; 0,7 2 ; 0,33. 

457 



On peut estimer que les especes qui avaient bien survecues 
initialement accusent une mortalite addi ti onnel 1 e raisonnable proche 
de : (0,o9 + 0,65 + 0,32 + 0,72 + 0,33) /5 soit 0,4 
La mortalite totale ultime etant 1,4 fois plus elevee que celle 
calculee pour la fin du printemps 1978 . 

2- PlfERSITE VES C0MP0RTEMENTS SPECIFIQUES 

Le comportement relatif des diverses especes est tres variable 
et assez imprevisi ble . 

En ce qui concerne les effets immediats pour une meme station 
certaines especes resistent parfai tement (T zllina te.nu.iA , Ouiznia 
fau.Aifaon.miA) d'autres sont presque i ntegral ement detruites {Vonax 
vittatuA , Can.dium zdulz, Ba.tkypon.zia, Eckinocan.diu.rn co fidatam , ?ha.nu.& 
Izgum&n, Eni>li> znAi.6, Eni>ii> Alliqua, Mact>ia coAall-ina, Lu.tia.tA.CL 
lu.tna.tiia.. Seules les trois premieres especes de cette liste sont 
timidement reparues aujourd'hui. 

A plus long terme, les comportemen ts sont aussi disparates : 

Te.llA.na te.nu.i6 non affecte a prospere jusqu'en 1980 et 
amorce une diminution de meme pour Ue.phtyi> homben.Qll. 

Tzllina &abula, 0we.nla fau.Aihon.mi6, kn.znic.ola. mafiina peu 
affectes initialement ont consi derabl ement regresses en 1979, 
quelquefois tres tardivement bien que certains signes d'un 
retabl i ssement certain apparaissent {An.znic.ola maxina) en 1981. 

Un.oth.oz zt Bath.ypon.zia qui avaient initialement disparus 
sont reapparus mais seulement dans la partie la plus occidentale 
et sans encore atteindre les densites initiales. 

Depuis 1980 on assiste a la reapparition de certaines especes 
qui avaient completement disparu apres la maree noire, Vonax 
vittatui se consolide alors que Nzninz cin.n.atu.lu.6 , EnAiA znbiA zt 
Can.dium zdalz ont du mal a se reimplanter. 

Des especes nouvelles pour la localite apparues en 1980 dont 
certaines seraient si gni f i cati ves d'une pollution residuelle, 
commencent a diminuer en 1981. 

On doit done considerer que les peuplements presentent encore 
en fin 1981 surtout dans la partie Est de la plage un desequilibre 
ecologique profond alors qu'a l'Ouest des signes d'une recouvrance 
avancee apparaissent. . co 

H JO 



3- EVOLUTION GLOBALE 

II semble s'amorcer une derive qualitative generale des 
peuplements de sables fins bien calibres tres typiques a Vonax 
v-ittatu-i, , Ttlllna fcabula, Ec.klyioca.fidlu.rn co nda.tu.m et grands Solznldaz 
vers des peuplements plus banalises de sables fins plus eutrophises 
qu'envases a Kfie.yilc.ola matiina. 

La maree noire n'est sans doute pas seule en cause ("irarees 
vertes") mais elle a accelere cette evolution regressive des 
peuplements originels. 

Les parties hautes et surtout basses de 1 ' estran, pi us que 
les niveaux medians, sont les plus touchees. Ceci coTncide avec 
une plus forte accumulation des echouages des nappes dans le haut 
de la plage et dans la moitie Est, suivie d'une persistance des 
hydrocarbures dans l'epaisseur du sediment. Ceci est conforme a 
ce qui a ete observe sur tout le littoral en matiere d ' accumul ation 
d ' hydrocarbures sous l'influence des vents d'Ouest dominants. 

La forte regression constatee dans le basde l&pl age , confirmee 
par la nature essentiel 1 ement infratidale de la grande masse des 
cadavres retrouves dans les echouages, souligne un autre fait majeur 
en dehors des hauts de plage directement atteints par les nappes, 
1'essentiel de la mortalite est a imputer au petrole disperse ou 
dissout au sein de la masse d'eau. 

Au niveau biomasse totale, on constate une chute importante 
en 1978 et 1979 par rapport a 1964-1968. Des af f ai bl i ssements des 
noyaux de peuplements de la partie Est par rapport a ceux de la 
partie Ouest, et du bas par rapport au haut, sont tres notables. 
Cette distribution se maintient en 1980 puis 1981 en s ' appauvri ssant 
encore. Notons que la progression des Atiznico la, se fait au depend 
d'especes de petite tail 1 e plus productives. II en resulte done 
une baisse generale de la fertilite de l'ensemble de la baie par 
rapport a 1968 de 1'ordre de pres des deux tiers. 

Le retabl i ssement encore tres incomplet des peuplements 
demanderaib des etudes ulterieures. 



459 



BIBLIOGRAPHIE 

Beauchamp P, 1914. — Les greves de Roscoff. Le Chevalier ed. Paris. 

Chasse CL L'Hardy-Halos M. T, Perrot Y, 1967. — Esquisse d'un bilan des pertes biologiques 

provoquees par le mazout du Torrey-Canyon sur le littoral du Tregor. Perm ar Bed, 6, 50, 

pp. 107-112. 
Chasse O. et colL 1967. — La maree noire sur la cote Nord du Finistere. Perm ar Bed, 6, 50, pp. 99- 106. 
Chasse CL, 1972. — Economie sedimentaire et biologiquc (production des estrans meubles des 

cotes de la Bretagne). These d'etat. Paris VL 1-293. 
Chasse CL 1978. — Bilan ecologique provisoire de rimpact de 1'echouage de V AMOCO CADIZ. 

Inventaire et evaluation de la mortalite des especes touchees. Public. CSEXO. 
Chasse CL 1978. — Un indice malacologique pour mesurer rimpact ecologique de la maree noire de 

VAMOCO CADIZ sur le littoral Haliothis PV : 9. n° 2, pp. 127-135. 
Chasse CI, 1978. — Esquisse d'un bilan ecologique provisoire de rimpact de la maree noire de 

VAMOCO CADIZ sur le littoral. Public. CNEXO serie actes de colloques. P, n° 6, pp. 1 15-135 

Congres AMOCO CADIZ Brest 7 juin 1978. 
Chasse CL Morvan D, 1978. — Six mois apres la maree noire de I' AMOCO CADIZ, Bilan pro- 
visoire de I'impact ecologique. Pern ar'Bed. PV, n° 93, pp. 31 1-338. 
Chasse CL 1979. — Bilan ecologique de I" AMOCO CADIZ. Evaluer pour dissuader. J. rech. Oceano. 

n° 1, pp. 25-26. 
Toulmond A, 1964. — Les Amphipodes des facies sableux intertidaux de RoscofT. Apercus faunis- 

tiques et ecologiques. Cah. biol Mar^ 5, pp. 319-34Z 



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461 



COUREE DE L EVOLUTION DES BIOMASSES 



Moyenne de 10 stations de bas de plage. 

Les nombres d' individus au m* et de la biomasse en cal/n 
pour tous les especes examines (44 especes differentes) 
sont disponibles sur demande de l'auteur. 



|000 _ BIOMASSE (col/rn ) x +1 



500- 



100- 



Tt Tellina tenuis Tf 

Dv Donax vittatus Nh 

Am : Arenicola marina Ow 

Bath: Bathyporeia Uro 



Tellina fabula 
Nephtys hombergil 
Owenia fusiformis 
U rot hoe 




50 -U 



•^/ 




1963 JANV 



JANV. 80 



JANV. 81 



AMOCO (mart) 
CADIZ 



TEMPS (mois) 



A62 



Morphologie di 
1 'escran 




Penneab 


Lite A 






Kt& I st Et,L '™ 1 


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EMPLACEMENT DES STATIONS DE PRELEVEHENTS . 



1 RUISSEAtfX. 



' 4 \ 5 



2 NAPPES DE RUISSELLEMENT. 



3 GRANDS RIPPLE-MARKS. 



4 HERBIER DE ZOSTERA NANA I979 

5 HERBIER DE ZOSTERA NANA 1 964-I 




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