NOW, OuW Gmhnttxi^l Skdf TtosT- m ®i %id «ss$ <^c March 1980 *t*T OFco. * V .1 ♦* Q c- o Prepared for: . U.S. Department of Commerce J National Oceanic and Atmospheric Administration ^* Outer Continental Shelf Environmental Assessment Program pa n> o oo o o to P3 H c c+ o H H" 3 ffi 0> I of Temora longicornis . ;s in the gut. 3 on feeding appendage. ;on, As^co Laboratory. r- O- z; ! TORO „■.„.. „ I SITE >^ <^STATION TJ station m> STATION VI y \ *ty 5 km Fig. 4.1 Position of stations II, III, IV, V and the reference stations I and VI. 63 using the Utermohl (1958) technique. Small cells (<10 (jm) , with 1-4 flagellas, belonging to Chrysophycea , Cryptophycea and Chlorophycea we ± counted collectively and are referred to as monads. 4.2.2.2 Primary production Water samples were collected, while carefully avoiding surface oil films, and incubated for four hours at 0, 1, 2, 4, 6, 8, 10, 15, and 20 m depth. Dark bottles were incubated at 0 and 20 m depth. Measure- ments were carried out as described by Larsson and Hagstrom (1979). 14 Four (jCi of carrier free NaH CO were added to all bottles. After incubation, 10 ml of the samples were transferred to scintillation vials, and counted in Instagel (Packard Instruments) in an Intertech- nique SL 40 liquid scintillation counter. The uptake of carbon was calculated according to Gargas (1975). 4.2.2.3 Bacteria Bacteria were sampled at a depth of 2 m using a sterile Niskin water sampler. At reference station VI the number of bacteria was determined in an integrated water sample (equal aliquots of water from 0, 5, 10, 15 and 20 m were pooled - a standard procedure in the routine programmes at these stations (see Hagstrom et al., 1979). The bacteria were preserved in formaldehyde containing acridine orange and counted in an epif luorescence microscope, as described by Hagstrom et al. (1979). They also described the method used for determining the frequency of dividing cells (FDC). 4.2.2.4 Zooplankton Zooplankton was sampled by vertical net hauls from bottom to sur- face, using a UNESCO WP-2 net with 90 |Jm mesh size. Special efforts were made to avoid contamination from surface oil films. The samples were preserved in 4% formaldehyde buffered with hexamine. Counting and species determination were performed using an inverted microscope. 64 4.2.2.5 Sedimentation Sediment traps, a PVC cross with 20 cylindrical glass tubes (0 26 mm, length 200 mm), were positioned at a depth of 20 m. The sedimented matter was divided in two parts; one was used for deter- mination of dry weight and the other was transferred to a glass jar (cleaned with hexane) and stored deep frozen until analysed for oil. 4.3 Results 4.3.1 Phytoplankton 4.3.1.1 Phytoplankton biomass At both reference stations, total phytoplankton biomass remained -2 fairly constant, around 600 mg C m , throughout the period (Fig. 4.2). In the impacted area phytoplankton biomasses were mostly more than a factor of two higher in the two weeks following the spill, but gradually decreased and approached the level at the reference stations by the end of November. There is no significant difference between the two stations (IV and V) in the impacted area (p = 0.32, rank sum test according to Dixon and Massey 1969:345), but valid statistical comparisons between the impacted area and the reference stations cannot be made, due to the long time spread and few measurements at the latter stations (see Fig. 4.3). 4.3.1.2 Phytoplankton species composition At all stations monads constituted 75 to 90% of the total biomass and diatoms 10 to 15% (dominating species: Coscinodiscus granii and Skeletonema costatum) throughout the investigated month. The remaining few percent were peridineans (Gymnodinium sp . and Gyrodinium sp.). A few species belonging to Cyanophycea and Chlorophycea were also present, but their contribution never exceeded one percent. This is not an abnormal phytoplankton composition for autumn in this area (Hobro, in press) . 65 2 O ft o Eh ft I U 0 J I I I I I I I U_l L I I I I I I I I I I I 1 I I L 25* OCTOBER 7 9 11 14 NOVEMBER 17 Fig. 4.2 Phytoplankton biomass, gC m , at stations IV ( — ), V (o o) and the reference stations VI ( C3 ) and I ( ■■ ) . Date of grounding is narked with an arrow, 23 INSOLATION -2 -1 cal cm d 300' H O — < P I O OS CN Pu I E g 200' S 100- -2000 1600 -1200 800 400 25 -1 — i — I u J — i — i — i — l i i i I i i i i i i A OCTOBER 9 11 14 NOVEMBER -1 17 J I I L 23 Fig. 4.3 Primary production, mg C m d , at stations IV ( ), V (o — o) , and reference stations VI (CD ) and I (■ ). Insolation values (dotted line) are scaled at the right Date of grounding is marked with an arrow. 66 A. 3. 2 Primary production The reference stations showed the normal autumnal decrease in primary production, compared to unpublished Asko Laboratory data from six previous years, with values at the end of November only one fourth of those at the end of October (Fig. 4.3). The primary production in the impacted area tended to be higher compared to values from the refer- ence stations. Fluctuations were induced by changing light conditions, (dotted line in Fig. 4.3), as indicated by the rather clear correlation (linear regression, r = 0.45, N = 17, all stations combined) between insolation and primary production per biomass (Fig. 4.3 and 4.4). Sta- tion V in the most contaminated area, normally had higher primary pro- duction than station IV, and the difference borders on statistical significance (p = 0.06, sign test, Dixon and Massey, 1969: 335-340). 4.3.3 Bacteria The total number of bacteria was higher at the contaminated sta- tions than at the reference stations (Fig. 4.5). Five days after the grounding there were about three times as many bacteria at stations II and III (1.15 x 106 ml"1) compared to station VI (0.35 x 10 ml" ). In November, the difference was a factor of about two. Hagstrom et al. (1979) reported the standard deviation of bacterial counts to be 9 ± 4%, which supports the reality of the observed differences. The difference in sampling strategy is unlikely to influence the results markedly, since bacteria are rather uniformly distributed in the water column during this time of the year (Hagstrom et al., 1979). In a comparison with data from the same time of year from both station VI (1977 and 1978) and two stations (1977) in the more eutrophicated area north of station I, the bacterial counts from the oiled area stand out as unusually high (Hagstrom et al . , 1979; Larsson and Hagstrom, pers. comm. ) . The measurements of the frequency of dividing cells (FDC) showed no clear differences between stations (Table 4.1). 67 en en $ o W CO H U P o o M Fig. 4.4 7 9 11 NOVEMBER OCTOBER The production per unit of biomass at stations IV ( — ) , V (= — «») , and reference stations VI ( C3 ) and I ( ■■ ) . Date of grounding is marked with an arrow. o CO u cu x> 6 3 C W H < pa NOVEMBER Fig. 4.5 Bacteria, V (o o), station VI (en ) . with an arrow. numbers x 10 ml at stations IV (~ \ II (•) , III (v) and at reference Date of grounding is marked 68 Table 4.1 Frequency of dividing bacterial cells (FDC) Date FDC% reference VI II oil stations III IV V Oct. 26 31 Nov. 5 9 11 14 23 2.3 2.2 1.7 1.7 2.2 1.9 3.3 1.8 1.8 1.6 2.0 1.0 mean S.D. 1.83 0.72 1.75 0.13 2.32 0.67 mean of polluted area (II-V) S.D. 2.04 0.54 69 4.3.4 Zooplankton The ciliate biomass shoved no consistent differences between the stations (Fig. 4.6). The net zooplankton biomass (Fig. 4.7) did not diverge from the reference stations, except very near the tanker (sta- tion II) in the days immediately following the spill. The zooplankton community was mainly composed of copepods (Acartia spp., Eurytemora sp. and Temora longicornis) and rotifers (mainly from the genus Synchaeta) . No changes in the genus or species composition or in the developmental stages of copepods could be found. The zooplankton was found to be contaminated with oil droplets. Oil was mostly observed adhering to the furca or the feeding appendages but was also found in the gut. Approximately 50% of the net zooplankton was contaminated during the first weeks after the grounding. After three weeks about 20°/o were still contaminated. 4.3.5 Sedimentation The amount of sedimented matter in the impacted area is shown in Table 4.2, and was relatively high during the first weeks after the -2 -1 spill, 6-9 g dry weight m d . From mid-November on, rates -2-1 were decidedly lower, 3-4 g dry weight m d . At reference station VI, rates were somewhat lower at the beginning of November but higher at the end of the investigation period. Calculations based on the results from the oil analysis shown in Table 4.2, Fig. 4.8, show the amount of oil sedimented per square meter per day. The high amount of oil found in sedimented matter also at station IV, located more than 2.5 km upwind of the tanker, is notable. 70 • 00 Ciliate biomass, mg C m "" , at stations IV ( ), (o o) , and reference stations VI (ca ) and ( • ) . Date of grounding is marked with an trrow. CM I 3 60 o H 33 o o CO OCTOBER 7 9 11 NOVEMBER -2 Fig. 4.7 Zooplankton biomass, g wet weight n , at stations II (* *), IV ( ), V (o o) , and reference stations VI (a ) and I (■). Date of grounding is narked with an arrow. 71 T3 01 a 0) E •H "O 01 co 4-1 o CO 4-1 c 3 O s (0 o 4-1 "0 d (0 ^ u cu *-> 4J CB E T3 /-> 0) TD 4-> O a •H cu S-l £ 0) •H VM ~ CD S-t CQ 01 ft <4H o T3 c 4-> « -C 60 >. •r-l aj 01 73 3 u >> 01 S-l a. XI >• — ' a 01 •H S-l i— I 0) 3; 4h u O , )-i 4-1 T3 O ■ I o oo c o oo U 2. -c CM S-l 01 E 4-1 4-1 4-> <0 s E >1 S-l T3 ~ 01 CO M T3 O ■H S-l 01 c o (0 4-1 CO 0 so on r~~ i — i l/o r-~ o a\ oo \o -t h o LD CM r-^ Csl X X inco n O sO LD r- so csi CM i— 1 CO SO r-l 00 00 CO r-l o oo o o CM LOCOCO W vO CTi On CO O" so r^ * r— 1 r— i r-» r— 1 p^ CM r~ CM c^ i—4 CJ on r— 1 U c* i— i u >' > 0) > > 0) > > dJ o o Q o ■O a o o a z 1 z 1 i z 1 z 1 i Z 1 z 1 i 1— 1 Oi <— i CM en r— I CM en i— i >>> >>> >>> ooo ooo ooo zzz zzz zzz S-l 01 4-1 p. -G u E o S-l Ol 3 — i (0 > 3 n3 01 0) oo c •H CO 3 •3 01 4-1 n3 r-l 3 CJ r— I 03 CJ "3 01 4-> 3 01 E •r-t ■3 01 ca 4-1 O 4-> 3 3 O 00 3 CO CO S-l OJ 4-1 4-> (0 E -3 0) 4-1 3 CU E •H ■a • cu > co T3 4-1 C O aj 4-1 > 3 HH 3 O CO E 3 « O a o 4-> to 4-1 03 CO 03 a x 72 BB - 40 a CM 1 E3 0 oo 6 -40 i-5 t-i O 20 Q W H 0 Z W E0 S M n 4D 20 '1 OCTOBER 9 17 NOVEMBER station V station II station IV 14 21 DECEMBER r ,-, -2 .-1 Fig. 4.8 Sedimented amount of oil, mg m d at stations V, II and IV. Calculated as explained in Table 4.2. 73 4.4 Discussion The pelagic system is first to suffer from an oil spill. Depending on local geography, distance from shores, windstress, etc., the exposure of the pelagic system to oil will change over a period of time. Soon after release from the tanker the oil starts to change both chemically and physically, e.g., volatile fractions evaporate and soluble fractions enter the water phase. The rate of this process decreases rapidly with time. Combined with a continuous dilution this weathering will limit the period of detectable ecological effects. The results from this study show only minor effects on the pelagic system. Changes in species composition could not be detected either in the phytoplankton or the zooplankton community. The phytoplankton biomass almost certainly increased in the affected area. This may have been due to decreased zooplankton grazing or increased growth rate. The existing data on productivity per unit biomass indicated a normal ratio, and the fact that zooplankton was found to be heavily contaminated with oil (50% of specimens with visible oil droplets in the first week, 20°/o after three weeks), mainly on the feeding appendages, makes decreased zooplankton grazing the more probable explanation. Similar results were found after the blow-out on the Ekofisk Bravo platform (Lannergren, 1978). No significant differences in zooplankton composition or biomass could be detected, except at station II immediately after the spill, when two measurements from separate days (Oct. 28 and 29) showed a drastically lowered biomass. Gyllenberg and Lundqvist (1976) have shown that zooplankton, when exposed to oil, either try to escape or enter a state of "narcosis". Either of these mechanisms could explain the very low biomasses near the wreck. Bacterial abundance increased in the contaminated area. It is however, impossible to judge whether this was a consequence of increased growth rate or decreased grazing. An effort was made to estimate bac- terial growth rate from the frequencey of dividing cells (Table 4.1), but no clear differences were found between polluted and unpolluted areas . Ih Perhaps the most interesting results from the pelagial study were obtained from the sediment traps. During the first period of sediment trapping (Nov. 1-9), very high amounts of oil (up to 0.7%) were recorded in the sedimented matter. This was also true for station IV situated about 2.5 km windward of the tanker. Unfortunately, no traps were positioned before November 1st, which leaves the period just after the spill, with potentially high sedimentation of oil, uncovered. This is likely to be a larger source of uncertainty in the following calcula- tions, than the methodological uncertainties inherent in all attempts at measuring sedimentation. Between Nov. 9 and Nov. 17 there was still a substantial oil content in sedimented matter at stations II and V, whereas at station IV practically no oil was found. From Nov. 17 on- ward, oil was still found in sedimented matter from station V, probably as a consequence of release from the shores due to waves and cleaning operations . Several mechanisms can facilitate sedimentation of oil, e.g., weathering of the oil leading to increased density, adsorption of oil to particles, or ingestion by zooplankton. Conover (1971) found oil incorpor- ated in zooplankton fecal pellets, a mechanism which, through the rela- tively high sinking rates of fecal pellets, will accelerate sedimenta- tion. In the present case it is, however, unlikely that zooplankton itself or the production of fecal pellets significantly contributed to the sedimentation of oil. At this time of year zooplankton biomasses are low, near the yearly minimum. A more probable path is sedimentation through adsorption to detritus particles, since seston levels in the area are normally high in the autumn, due to wind-induced re-suspension of bottom sediment. Only two days before grounding, the area was sub- ject to fairly strong southwest winds. Wind speeds of up to 10-14 m/s also occurred several times during the acute phase of the spill. The sediment trap data make it possible to estimate roughly the amount of oil leaving the water phase through sedimentation. The af- fected area has been estimated as the area inside a line connecting the outermost points where oil has been found, either through visual observa- 2 tion (Fig. 4.9) or by direct measurements of oil. A total area of 42 km 75 N ) , in which oil was observed on the _ surface (see Fig. 4.9), estimated to be 34 km , Area(//) bounded by lines connecting sta- tions where oil was analytically demonstrated (additional 8 km ) . 78 4.7 References Bender, M.E., E.A. Shoarls, R.P. Ayres, C.H. Hershrier, and R.J. Hugget. 1977. Ecological effects of experimental oil spills on the eastern coastal plain estuarine ecosystems. In: Oil spill, behavior and effects, 1977 oil spill conference, 505-509. Conover, R.J. 1971. Some relations between zooplankton and bunker C oil in Chedabucto Bay following the wreck of the tanker Arrow. J. Fish Res. Bd. Can. 28: 1327-1330. Dennington, V.N. , J.J. George and C.H.E. Wyborn. 1975. The effects of oils on growth of freshwater phytoplankton. Environ. Pollut. 8: 233-237 Dixon, W.J. and F.J. Massey, Jr. 1969. Introduction to statistical analysis. McGraw-Hill Kogakusha, Ltd. Tokyo, 1-637. Gargas, E. 1975. A manual for phytoplankton primary production studies in the Baltic BMB. Publ. 2, 1-88. Gordon, Jr. D.C. and N.J. Prouse. 1973. The effects of three oils on marine phytoplankton photosynthesis. Mar. Biol. 22: 329-333. Gyllenberg, G. and G. Lundqvist. 1976. Some effects of emulsifiers and oil on two copepod species. Acta zool. fennica 142: 1-24. Hagstrb'm, A., U. Larsson, P. Hb'rstedt , S. Normark. 1979. Frequency of dividing cells (FDC) - a new approach to the determination of bacterial growth rates in aquatic environments. Appl. Environ. Microbiol. 31(5): 805-812. Hobro, R. 1979. Annual phytoplankton successions in a coastal area in the Northern Baltic. In: Cyclic phenomena in marine plants and animals (Eds. E. Naylor and G.R. Hartnoll). Pergamon Press, Oxford, 3-10. H'siao., S.I.C., D.W. Kittlet and M.G. Foy. 1978. Effects of crude oils and the oil dispersant corexit on primary production of arctic marine phytoplankton and seaweed. Environ. Pollut. 15: 209-221. Kuhnhold, W.W. 1978. Impact of the Argo Merchant oil spill on macro- benthic and pelagic organisms. Paper present at the AIBS Conference on assessment of ecological impacts of oil spill, 14-17 June 1978, Keystone, Colorado, USA, 152-179. Lannergren, C. 1978. Net- and nanoplankton: effects of an oil spill in the North Sea. Botanica Marina, vol. XXI: 353-356. Larsson, U. and A. Hagstrbm. 1979. Phytoplankton extra-cellular release as an energy source for the growth of pelagic bacteria. Mar. Biol. 52: 199-206. 79 Lee, R.F., M. Takahaski, J.R. Beers, W.H. Thomas, D.L.R. Seibert, P. Koeller and D.R. Green. 1977. Controlled ecosystems: their use in the study of the effects of petroleum hydrocarbons on plankton. In: Physiological responses of marine biota to pollutants (Ed. by F.J. Vernberg, A. Calabrese, F.T. Thurberg and W.B. Vernberg) . Academic Press, 323-342. Michael, A.D. 1977. The effects of petroleum hydrocarbons on marine populations and communities. In: Fate and effects of petroleum hydrocarbons in marine ecosystems and organisms (Ed. by D.A. Wolfe). Pergamon Press, New York, 129-137. Mironov, D.G. 1968. Hydrocarbon pollution of the sea and its influence on marine organisms. Helgolander Wiss. Meeresunters . 17: 335-339. Nelson-Smith, A. 1970. The problem of oil pollution of the sea. In: Advances in marine biology 8 (Ed. by F.S. Russel and M. Yonge) . Acad. Press, London, 215-306. Parker, C.A. and R.G.H. Watson. 1969. Uptake of oil by zooplankton - the ultimate fate of crude oil at sea. Interim report no 5. Admiralty materials laboratory, Holton Heath, Poole, Dorset. AML Report no. B/198 (M) . Prouse, J.J., D.C. Gordon Jr. and P.D. Keizer. 1976. Effects of low concentrations of oil accommodated in sea water on the growth of unialgal marine phytoplankton cultures. J. Fish. Res. Bd . Can. 33: 810-818. Sandborn, H.R. 1977. Effects of petroleum on ecosystem. In: Effects of petroleum on arctic and subarctic marine environments and organisms (Ed. D.C. Malins). Academic Press, New York. 337-357. Straughan, D. 1972. Biological effects of oil pollution in the Santa Barbara Channel. In: Marine pollution and sea life (Ed. M. Ruivo). Fishery News, 355-359. Utermohl, H. 1958. Zur Vervollkommung der quantitativen Phytoplankton- Methodik. Verh. Int. Verein. theor. angew. Limnol. 9: 1-38. Winters, K., R. O'Donnell, J.C. Batterton and C. VanBallen. 1976. Water-soluble components of four fuel oils: chemical characteri- zation and effects on growth of microalgae. Mar. Biol. 36: 269-276. 80 5. NOAA Acute Phase Experiments on Pelagic and Surface Oil CHAPTER 5: NOAA ACUTE PHASE EXPERIMENTS ON PELAGIC AND SURFACE OIL (John Kineman, 5.1, 5.3-5.5; Robert C. Clark, Jr., 5.2) The major events leading to the NOAA/OCSEAP Spilled Oil Research (SOR) Team response to the Tsesis incident have been mentioned in the Executive Summary. The present section describes the short-term phase activities of the U.S. team. 5.1 Experiment Design Objectives were limited to investigating the accommodation of oil in the water column below a contained oil slick, and subsequent down- stream decay. It was envisioned that this would require locating a significant quantity of pooled (or boomed) oil, then sampling the oil and the water at various depths and times to determine accommodation and composition over time. Secondly, to determine downstream decay, the plan called for sam- pling at various depths in the water column, while following a parcel of water as a "Lagrangian" drift study. The original plan also called for determining currents, using sampling over a period of 8-12 hours (for each experiment) and extracting water samples in the field. After arrival on-scene, and during the two days in the field, modifications were made to the original experiment design to adapt to existing conditions. The chemistry program that was carried out is outlined below: A. Oil chemistry studies (1) Surface oil samples were taken for: a. estimation of the degree of emulsif ication b. estimation of the density of the free oil c. estimation of the asphaltic content based on the hexane insoluble residue 83 (2) Samples of the cargo oil were taken for: a. analysis of chemical composition for reference to future samples and for weathering studies b. determination of the physical chemistry of the oil B. Water column studies (1) Lagrangian drift samples (repetitive sampling of a dyed parcel of water) to determine dispersion of subsurface oil down-current from a contained surface slick. (2) Eulerian sampling at biological stations established by the Swedish scientists, to determine concentrations at various times . (3) Water column samples in an area known to have been heavily polluted and since blown clear of floating oil, to determine subsurface hydrocarbons remaining several days after the passage of a floating oil slick. (4) Water column samples below a moving oil slick (emulsion) to determine waterborne hydrocarbons. (5) Filtration of various samples to determine particle size distributions of accommodated oil under various conditions. (6) Extraction of selected split samples with both hexane and CC£, , to compare methodologies of UV-fluorescence . C. Aerial mapping of visible floating oil, concurrent with sampling. 5.2 Hydrocarbon analysis associated with the Tsesis oil spill During the NOAA team response, petroleum samples were collected, and duplicate sets were distributed to Energy Resources Company, Inc. (ERCO) and the Northwest and Alaska Fisheries Center (NWAFC). This section describes the analysis performed at the NWAFC (information from the ERCO set is reported in Chapter 11). Although the water content of the mousse samples varied from 12% to 76% by volume (Table 5.2.1), the normal paraffin distribution of the water-free oil fraction of all three of the mousse samples was identical, within experimental accuracy, to the cargo sample (Table 5.2.2). The cargo sample had been collected after the oil had been off-loaded from the Tsesis and shipped to its original destination at Sodertalje. The 84 ■ w — < , a — — ■ — i o L. - ~ ji— I — N % o CN r\i lTJ r-. c £> 1) — l — 1 /- c > : u (0 c 1*- u. < -»«». 00 XI m OJ CM 1 — 1 r» r*- *J - i — i ZC ^z rsi 3 r-. i — r^ ■c r- r^ r — r^ L r— "••». -^. r- 4-> \ Hi U -r Csl m ■ — i - *-^ *-^. ■T) o o a 0 c to c u - n E- T3 Sm a g *" • >■ in — rj 85 Table 5.2.2 n-Paraffin Hydrocarbons in Tsesis Oil Samples (ppm, water-free whole oil) Hydrocarbon Cargo Oil Recovery Tank Tsesis Boom Svardsf jarden 10 278 8 115 44 11 4,480 6,060 1,540 602 12 7,480 8,100 5,020 6,120 13 13,800 14,000 10,100 10,200 14 15,000 16,000 14,300 13,200 15 14,100 15,300 14,400 11,500 16 11,300 11,400 11,900 10,500 17 9,610 10,300 10,700 7,520 pristane 5,230 5,360 5,770 3,720 18 6,570 7,490 7,980 6,160 phytane 4,820 5,260 5,330 4,890 19 5,950 6,100 6,560 5,810 20 4,660 4,470 4,670 4,520 21 3,040 3,370 3,330 3,050 22 2,960 3,130 3,190 2,670 23 1,970 3,000 2,270 1,880 24 1,660 1,860 1,950 1,570 25 1,520 1,420 1,630 1,280 26 1,410 1,350 1,410 1,240 27 851 922 880 813 28 660 728 787 677 29 818 788 812 798 30 534 690 649 587 31 215 302 352 260 32 182 158 200 163 33 265 238 184 191 34 369 400 342 344 35 618 446 595 503 36 127 218 205 161 37 60 73 27 76 Total hydrocarbons 120,000 128,000 117,000 101,000 0~Cl4_37 84,500 89,400 89,300 75,000 n-Cj 7 /background 4.0' 4.0 3.9 4.0 n~^2 &l background 1.3 1.3 1.3 1.3 n-C17/pristane 1.8 1.9 2.0 2.0 n-Cjg/phytane 1.4 1.4 1.5 1.2 Cn50% 11.8 11.9 12.6 12.6 Major hydrocarbon 14 14 15 14 % 12% 13% 12% 13% 86 mousse sample (Recovery Tank) containing 12-18% water, had been col- lected the second day ot the spill i rum a barge tank after the oi] had been vacuum-pumped from the sea surface inside i containment boom placed immediately adjacent to the grounded vessel. Residence time of the free oil was estimated by the Asko scientists to be on the order oi minuti to perhaps as long as an hour. The oil collected on the east side oi Svardsf jarden had been carried there by the wind and was estimated to have been exposed to wi tthi i Lng for at least three days. The sample from the boom near the grounded Tsesis may have been more intermediate in age due to its close proximity to the grounded vessel. There appears to have been a slight degree of weathering ol the n-paraffins below n-C, „ in the oldest oil collected in Svardsf jarden, although this evaporative loss was slight. For example, the equivalent n-paraffin carbon number where environmental losses of 50% are evident in the unresolved envelope under the n-alkane peaks (using the method of Blumer et al., 1973) shifted from 11.8 n-paraffin equivalent carbon numbers for the unweathered oil, to 12.6 for Svardsf jarden oil. The saturated and unsaturated hydrocarbon contents of the oil in the boom near the vessel and the oil taken from the recovery tank were similar to the cargo oil, but the oil from Svardsf jarden showed a marked decrease in both fractions with an apparent increase in material not recovered from the silica gel/alumina chromatography. This result suggested an increase in polar material in the Svardsf jarden sample which had the longest time available for weathering. The plotted n-paraffin patterns show nearly identical shapes, though there is visual evidence for some possible loss below n-C 0 in the more heavilv weathered Svardsf jarden — lo slick mousse sample (Fig. 5.2.1). 5.3 Water samples with a sterile bag sampler Details of the water column study (methods and results) are not reported here because the data were invalidated by a sample processing error. All water column sampling performed by the U.S. team was done using a Niskin sterile plastic bag, "Butterfly" sampler. This sampler 100,000 -i 50,000 o Cargo oil • Recovery tank oil ^ Downwind boom oil ■ Svardsfjarden slick oil 10,000 - 5,000 - 1,000 500 " 100 Carbon atoms / molecule Fig. 5.2.1 Normal paraffin distribution of water-free oil fraction of three mousse samples and cargo oil. 33 has been used successfully in previous and subsequent oil spill inves- tigations (e.g., Argo Merchant and Amoco Cadiz); however, in the Tsesis study, water samples were allowed to remain in the sample bags (albeit refrigerated) for times ranging from one day to one week. The analysis of the water sample extracts and subsequent chemical evaluation of the effect of the plastic bags, have been reported by Boehm and Feist (1977, 1978) under contract to OCSEAP. The major conclusions of this study were : (1) Organic compounds begin leaching from the sample bags almost immediately, reaching levels of 50-100 (Jg/1 well within 24 hours . (2) Gas chromatography and fluorescence results confirm that losses of sampled hydrocarbons (water soluble fraction of the Tsesis cargo) occur after 15 minutes of interaction with the sampler, and are total after 36 hours. (3) The Tsesis data set cannot be interpreted due to the effects of the polyethylene bags. The spectra of many Tsesis samples are identical to that of the bag leachate. Those few samples which exhibited spectra similar to Tsesis oil, "Type B" , revealed only very low concentrations. Considering the effect of the plastic bag, this presence of hydrocarbons (other than bag leachates) in some samples, would be the probable result of either high initial concentrations in the environment or relatively short storage times. It was unfortunate that SOR Team personnel also instructed Swedish scientists on the use of the plastic bag sampler, and encouraged those procedures over the use of glass jars in all water column sampling for hydrocarbon analysis. Later success using the plastic bag sampler at the site of the Amoco Cadiz spill is attributed to the immediate (within 2 minutes) transfer of the sample water to glass containers. 89 5.4 Water column data from two scuba-obtained glass jar samples 5.4.1 Results of Analysis: Two samples obtained in glass jars by Mats Notini during the first few days of the Tsesis incident were analyzed as part of the above mentioned analytical work performed by ERCO. These were samples A-l (1 meter depth) and A-2 (0.5 meter depth) taken on 11/1/77 at position D, in the enclosed bay at Lindholmen (see Fig. 7.1.1). Analysis (Boehm and Fiest, 1977) by UV-f luorescence indicated peak concentrations (at 310 nm) of 50.9 (Jg/ 1 and 58.2 (Jg/ 1 respectively. Both samples exhibited spectra, classified as type "B", similar to whole Tsesis oil. These two samples were not included in the first set that was selected for GC/MS analysis to identify compositional elements, and as this omission could not be corrected later, it was necessary to rely on the fluorescence spectra to infer that the contaminant was indeed Tsesis oil. Comparing these spectra statistically (above 308 run), the corre- lation coefficient between the water sample spectra and the whole oil spectra is about 0.97. The greatest differences, although slight, appear as lower concentrations of the lighter fractions. 5.4.2 Discussion: The two glass jar samples provided the only valid water column hydrocarbon concentration data. This sampling was done underwater, thus avoiding some of the problems of through-the-slick contamination. There is little question that direct sampling underwater incurs the least chance for contamination if careful procedures are followed. Although statistically insufficient, the two samples seem reliable in themselves, and can be useful as indications if assumptions can be made about varia- bility. Analytical variability (including the extraction precedures) can be determined from analysis of replicate extractions of the same sample. Differences between replicates of 21 samples ranged from 0 to 4 (Jg/1, implying good analytical and procedural control. 90 Environmental variability can not be determined from the plastic bag data. However, circumstances in the sample area (for the two glass jar samples) would lead one to expect a fair degree of homogeneity. The bay was small, enclosed, and shallow; the wind was directly into the entrance of the bay, therefore trapping the oil and providing an un- changing source (except for weathering). Also, the oil was in a stable, emulsified form, and mixing was low and uniform (no areas of high wave action or turbulence). There was time and the proper circumstances for factors to progress toward equilibrium. It is therefore consistent that, even with an hour between sampling times, the two concentration values were very close together. If these numbers are to be useful, it is important to note the environmental conditions under which they were produced. The samples were taken in the afternoon of the day after oil had first reached the site. The trajectory of the oil can be inferred from observations of the time that oil reached various shores (section 1.2 and Fig. 4.9) and from wind data (currents were minimal and tides were absent, so that trajectories were primarily wind driven). As recorded by SOR Team personnel, on board the research vessel Aurelia, the wind on the day of sampling (11/1/77) was steady at 10 m/s from 165 T all morning. In the afternoon the wind increased to 12-14 m/s but did not change direction. Throughout the previous day (10/31/77) the wind was steady from 180* T at 10-15 m/s. With such winds, it was virtually impossible for the site to receive fresh oil from the Tsesis , but rather the oil was that which had previously blown against the rocky shores of Liso Island. This deduction agrees with observations made by the Swedish scientists on 10/27, 10/30, and 11/1 (Fig. 4.9). Therefore, the oil had weathered between two and five days, traveled a total distance of about 10 km, and had been trapped for a while enroute, interacting with a rocky shore. Surface oil chemistry data (section 5.2) indicates that the Tsesis oil emulsified very rapidly, and all oil samples taken away from the immediate vicinity of the ship were close to fully emulsified. It is therefore quite certain that the oil in the bay when Notini's samples were taken was "mousse" containing about 75% water. 91 At the time of sampling, swells were approximately 15-20 cm, develop- ed over a short (7 km) fetch, and waves were estimated at 10-15 cm (SOR Team data). Mixing energy was thus low, so that one would not expect the mechanical entrainment of large droplets of oil. The slight losses of the lower weight molecules indicated by the fluorescence spectra, is similar to Clark's observation of losses in the surface mousse (section 5.2); indicating that the surface mousse is the likely source of the water column contamination. The great compositional similarity of the water column contamination with this mousse (probably even greater than that shown for whole oil) indicates two possibilities: accidental contamination of the sample jar by surface mousse, or the presence of micro-dispersed oil in the water column (the water soluble fraction would not be similar to whole oil). Accidental contamination of the sample jars would be expected to result in highly variable con- centrations. The nearly identical, low-level concentration values observed (one hour apart) would be an unlikely coincidence if resulting from accident, although additional data or more than two samples are needed to state this conclusively. Oil in micro-dispersed form, however, was also observed during this time period adhering to and being ingested by zooplankton (Chapter 4). The sedimentation trap results (Chapter 11) further suggest particulate oil in the water coli L umn . 5.4.3 Conclusion It can be concluded that concentrations of Tsesis oil of 50 to 60 (Jg/1 were observed by fluorescence at \ and 1 m depths in low mixing energy conditions, below a captured slick which was fully emulsified and which had weathered for 2 to 5 days. This oil was most likely micro- dispersed particles from the surface mousse. The oil in the water column (as with the surface mousse) bore great similarity in composition with the cargo oil, except for slight losses of the lighter molecules. This similarity can be attributed to the rapid emulsif ication reported by Clark (section 5.2), which retarded evaporative losses and other forms of physical weathering. 92 5.5 Aerial mapping of visible floating oil An aerial overflight was made on 11/1/77 by Dr. James Mattson, and the visible extent of surface oil was documented by photography using a Nikon 35 mm camera equipped with a time-recording data bank. The flight path and extent of surface oil are shown on Fig. 5.5.1. Some of the photographs appear in Appendix 2. 5.6 References Blumer, M. , M. Ehrhardt, and J.H. Jones. 1973. The environmental fate of stranded crude oil. Deep-Sea Res. 20:239-259. Boehm, P.D. and D.L. Fiest. 1977. Analysis of Tsesis oil spill samples: Fourth monthly progress report, NOAA Contract No. 78-4050. Energy Resources Co. February 16, 1978. Unpbl . Boehm, P.D. and D.L. Fiest. 1978. Analysis of water samples from the Tsesis oil spill and laboratory experiments on the use of the Niskin bacteriological sterile bag sampler. Report submitted to NOAA on contract 03-A01-8-4178 Energy Resources Company, Inc., Cambridge, Mass., July, 59 pp. (unpublished). Clark, R.C., Jr. 1974. Methods for establishing levels of petroleum contamination in organisms and sediment as related to marine pollu- tion monitoring. NBS Spec. Publ. 409, 189-194. Clark, R.C., Jr. and J.S. Finley, 1973. Techniques for analysis of paraffin hydrocarbons and for interpretation of data to assess oil spill effects in aquatic organism. Proced. 1973 Joint Confer, on Prevention and Control of Oil Spills, American Petroleum Ins., Washington, D.C., (13-15 March), 161-172. 93 ■^3 . .... * • — ~v ?v V i. - '7"* • «. N " *"'>'"* V~j ■'■ \-T- ■»•• V™" — -' .►»>'\--- ■. , .&--V* V*. — --'^Mx*' " "V" " ■1/ f\v~- 1 I ''.->v- 5:/*" 5 wuT\ « \ . - \ A .r ' • • •;. -w- . filsat K \v^ ■ 1 Figure 5.5.1 Aerial reconnaissance on November 1, 1979; wind from the south. Areas with heavy visible oil concentrations are indicated by dots Light sheen is not indicated. 94 6. Impact of Oil on Deep Soft Bottoms CHAPTER 6: IMPACT OF OIL ON DEEP SOFT BOTTOMS (Ragnar Elmgren, Sture Hansson, Ulf Larsson and Brita Sundelin) 6. 1 Introduction 6.1.1 Background Since the Torrey Canyon catastrophe in 1967, millions of dollars have been invested in research on the biological effects of oil pollu- tion of the seas. Innumerable scientific papers, summarized in many books and reviews (e.g. GESAMP 1977, Mclntyre and Whittle 1977, Cowell 1977), have resulted. Most of these studies have, however, been con- cerned either with the surface layer of the sea, where plankton, fish and fish eggs as well as sea birds may be affected by a spill, or with the intertidal zone, where stranded oil may cause extensive destruction of the natural communities . Relatively little attention has been given to the effects of oil on subtidal benthos communities, even if a few good field studies exist (e.g., Addy et al., 1979; the West Falmouth oil spill study, Sanders, 1978). These few studies are all, however, concerned only with the benthic macrofauna, while the smaller meiofauna is totally ignored, even though its importance in energy flow terms is often similar to that of the macrofauna. This general picture is also valid for the Baltic Sea. Furthermore the Baltic ecosystem has so many unique features, that the usefulness of studies from tidal and more fully marine areas for risk evaluation concerning various types of pollutants in the Baltic is questionable. Almost the only study of oil impact on a Baltic soft bottom community is that by Leppakoski and Lindstrom (1978), and treats continuous oil pollution from a refinery, rather than an acute spill situation. The small study of the Palva spill by Mustonen and Tulkki (1972) should perhaps also be mentioned, even though it is rather inconclusive. This comparative dearth of information is the more unfortunate, as studies from the intertidal zone show that recovery from an oil spill is slowest in fine sediment environments, where oil may persist virtually 97 unchanged in the deeper, oxygen-free layers for at least five to ten years (Krebs and Burns, 1977). This persistent oil continues to present a hazard to the biological community, preventing its return to pre-spill status, and constituting a potential source of slow, continuous oil leakage to surrounding areas (Vandermeulen and Gordon, 1976). 6.1.2 The spill area The Tsesis spill occurred in an area where benthic data have been collected since 1972 by Ulf Larsson, Asko Laboratory, in connection with a study of the environmental impact of the large modern sewage plant "Himmerf jardsverket" . Pre-spill macrofauna data were already available, while meiofauna samples are stored and will be sorted later if funding becomes available. Furthermore, the benthos of the Asko area has been treated in detail in a number of earlier papers (Cederwall, 1977, 1978; Ankar, 1977; Ankar and Elmgren, 1976; Elmgren, 1976) so that the back- ground knowledge for the study of the oil spill was exceptionally good. Stations 20 and 21 (see map, Fig. 6.1) were generally sampled for macrofauna once a year in October-November (i.e. at about the time of the spill) starting in 1972. The depth of the stations were: station 15: 44-45 m, station 20: 32-33 m, station 21: 28-29 m, and the bottom substrate, mud at all the stations. Stations 20 and 21 are located in an area, "Svardsf jarden" , which is cut off from exchange of deep water with the open Baltic by a sill of about 20 m depth between Asko and Toro, whereas Station 15 is outside this sill. 6.2 Methods 6.2.1 Sediment sampling Cores for oil analysis of surface sediments were collected using either a modified Kajak core sampler (Kajak et al., 1965) of 80 mm internal diameter (10 Nov. 1977, station 1 and 2; 17-31 August 1978, station 14, 15, 20, 20C, 20D) or the Asko corer, also used for meiofauna sampling (inner diameter 22 mm, used for all other samples). The top 2 cm of the sediment were extruded into hexane-washed glass bottles and kept deep-frozen until analyzed. On 4 December 1978, further cores 98 ^^ y ■ NN /— -\ ASKQIA3.> i s7 i i 4 r* N n J MOSKC* k i ; ■•' •< Stn I a TOSO JfGROUNDING \"> ft -«-§■ X S* V\ STN VI >• J^ a5-** -\ 4 '-, \ : Figure 6.9a. Embryos from Pontoporeia af finis, collected at station 20 in the impacted area. Most of the embryos are abnormal, and one egg (arrow) is not differentiated. Figure 6.9b. Normally developed embryos from the reference station (no. 15) 111 ID H rg o -- — ^ — o -3 o CN s£ c a o Oh — » e -: t en un O — r— I 112 than station 20. Samples from March, June and August 1978 have been sorted and this station has been followed intermittently since 1971. Pre-spill samples from further sampling occasions are available from all stations, but could not be sorted within the budget available. As is normal in fine sediments, nematodes totally dominated the meiofauna abundance at all stations and sampling occasions (Fig. 6.10 - 6.13). Except for an exceptionally low nematode value at Station 20 in March 1978 there were no statistically significant differences in nematode abundance between the stations. It is perhaps worth noting that the proportion of large nematodes was consistently higher at Station 20 than at Station 15 during the post-spill period. The ostracods often constitute the larger part of the meiofauna biomass in deeper Baltic soft bottoms (c.f. Ankar and Elmgren, 1976, for the Asko area), even though they are much less numerous than the nema- todes. At both station 21 (November 1976 pre-spill) and station 15 (post-spill reference station) moderate to high ostracod numbers were 4 2 found (5-17 x 10 ind/m ) whereas station 20 had very low ostracod 4 2 abundances on all post-spill sampling occasions (1-3 x 10 ind/m ). (See Fig. 6.11) . The rest of the meiofauna comprises a wide assortment of taxa , such as Foraminifera , the hydroid Protohydra leukartii, Turbellaria, Kinorhyncha, harpacticoid copepods and juvenile macrofauna (so-called temporary meiofauna - mostly Macoma balthica , Harmothoe sarsi and Halicryptus spinulosus larvae, but part of the year also juvenile Pontoporeia spp . ) . Each single group was too scarce in the samples for definite trends to be observed, but as an aggregate all these "others" (total meiofauna excluding nematodes and ostracods) showed a much lower abundance at station 20 (post-spill) than at stations 21 (pre-spill) and 15 (post-spill reference) (See Fig. 6.14). The Ockelmann dredge samples collected in February and March showed a much higher proportion of live ostracods in relation to total ostracods (live + "recently" dead) at station 15 than at station 20, where only few live specimens were found (see Fig. 6.13). The difference between the stations was highly significant on both occasions (p < 0.0001, 2 X -test). 113 10 8 -NEMATODES i nd . /m2 18^6 0 20 16 12 8 41- - OSTRACODS ind./m2 18^4 0 5 2 1 0 Fig. 6.10 Fig. 6.11 OTHER GROUPS i nd . /m2 13^5 Fig. 6.1: S O N D 1976 Fig. 6.10 - 6.12 J F M A M J J 1977 Abundance of nematodes, ostracods and other groups (excluding nematodes and ostracods) at station 20 (□ ) and station 15 (▼) . Data in 1976 from station 21 (A ) . Arrows indicate grounding of Tsesis. .14 en O u 03 U -P 05 o o 05 u iJ U X w < o H w 1 2 3 OSTRACODS (numbers per m2) 4 -10- Fig. 6.14 Abundance of ostracods versus abundance of other meiofauna groups (excluding nematodes and ostra- cods) in the Asko - Landsort area, (n ) Data from station 20 (mean of three cores) . ( T ) Data from station 15 (mean of three cores) . ( a ) Data from the Asko - Landsort area. Data from single cores taken at randomly selected stations in the depth range 25 to 45 m. 116 6.4 Discussion 6.4.1 Sediment samples No Tsesis oil hydrocarbons could be identified with certainty in any of the sediment samples. Nevertheless, we can state with certainty that oil must have reached the sediment surface, since 1) the sediment- ing material in the water column contained large concentrations (up to 0.7%) of oil, especially in the first week after the spill; 2) large Macoma balthica collected not only at station 20 but also at other stations (e.g., 5, 6 and 8) contained considerable quantities of oil hydrocarbons within about a month after the spill, when the first Macoma samples for oil analysis were collected (see Section 11 for details); and 3) a smell of oil was detected from several grab samples at Station 20 in November 1977. The failure to find oil in the sediment samples can probably be explained by several interacting factors. Newly sedimented oil will be concentrated in the uppermost flocculent surface layer of the sediment, and this layer is not well sampled by gravity corers such as those used in the present investigation (cf. Mclntyre 1971, Elmgren 1973). The sampling efficiency of the Asko corer for meiofauna has been tested by Ankar and Elmgren (1976). For the non-nematode meiofauna, which tend to live in the floccular top sediment, the efficiency was only 38-610/o. The Kajak corer has been shown to be even less efficient (Hallberg, BSgander and Elmgren, unpublished). After the sampler had been brought to the surface, it is highly likely that there was even further loss as the water, with its suspended load of oil-contaminated surface floe, was poured off from above the sediment, prior to extrusion and sectioning of the cores . Finally, the sediment contained fairly high concentrations of biogenic hydrocarbons and in some cases unidentified anthropogenic hydrocarbons as well and this tended to swamp the signal from the newly sedimented oil hydrocarbons. This is especially likely since sections as thick as 2 cm were used for all early sediment cores. 117 6.4.2 Macrofauna 6.4.2.1 Macrofauna community response The drastic reduction in macrofauna abundance at station 20 after the spill left little doubt that this was a direct effect of the oil. The three species which decreased in abundance were all vagile forms that may have emigrated from the area most heavily influenced by the oil. Initially it was thought this a more likely explanation of their virtual disappearance than direct mortality, since very few remains of dead animals were found in the benthos samples taken 16 days after the grounding of the Tsesis . Assuming that oil would take a couple of days to reach the bottom in quantity and that mortality would not have been instantaneous (that would probably have required oil levels high enough to kill Halicryptus and Macoma also), any animals killed by the oil would have had to disappear almost without a trace in about one week, which was not very likely at a bottom water temperature of 7 C, at least not for the cuticle-covered amphipods. Yablonskaya, (1947, quoted in Winberg 1971) found that Chironomus larvae were still recognizable after 30 days at 5 C, and after 12 days at 10 C. Later simple aquarium experi- ments with dead Pontoporeia af finis, kept in natural sediment at field temperature, have indicated that 1-2 weeks might indeed be enough time for the dead animals to disappear almost completely (Sundelin, unpubl.). That amphipods actively avoid oil-contaminated sediments has been shown experimentally by Percy (1977) for Onisimus affinis and the same is true for Pontoporeia affinis (unpublished experiments by M. Notini, pers. comm.) and probably also for P. femorata (Atlas et al., 1978). At present it is therefore impossible to say with certainty whether most of the amphipods emigrated or died. The only natural environmental perturbation that could have been expected to give a reduction of the macrofauna as drastic as that found at station 20 would have been a period of oxygen deficiency during the autumn or late summer preceding the spill. The reduced sediment surface and fairly low oxygen values found at station 20 in summer 1978 (post- spill) could be taken as indicating that even lower oxygen values might have occurred the year before. However, several lines of evidence contradict this hypothesis. First, bottom oxygen values at the three permanent stations in the "Himmerf jard" were unusually good during 1977 118 (Larsson, unpubl.), even in the heavily eutrophicated innermost parts of the Himmerfjard, where bad oxygen conditions are normal in late summer and early autumn. Second, oxygen deficiency would not have resulted in a decrease in Harmothoe sarsi , which normally is the macrofauna species most tolerant towards oxygen deficiency in the northern Baltic proper (e.g., Cederwall, 1978). Finally, since there is no question of any oxygen deficiency occurring after the breakdown of the thermocline in early October 1977 or before late summer 1978, one would have expected considerable re-invasion by Pontoporeia and Harmothoe from the surround- ing areas during the 9-10 months of good oxygen conditions. There is little evidence of such an immigration to station 20, the variations noted being more likely due to the natural patchiness of the benthos (since Macoma balthica which is sedentary also varied). The continued presence of repellent oil hydrocarbons in the sediment indicated by continued high hydrocarbon levels in Macoma balthica from station 20 could, on the other hand, easily explain the absence of immigration during the first ten months following the spill. The impact of the oil spill on the macrobenthic community at sta- tion 20 was clear, but not totally catastrophic. While total abundance declined drastically, due to the reduction in abundance of Pontoporeia (both species) and Harmothoe, there was little change in biomass, since this is dominated by Macoma balthica, which did not decrease. The abun- dance of the two macrofauna species without swimming ability, and with generally low mobility, Macoma and Halicryptus, seem to have been little influenced by the spill, even though Macoma, at least, showed consider- able contamination by oil hydrocarbons (see Section 11). The relatively low sensitivity of Macoma balthica to oil pollution, coupled with its ability to take up hydrocarbons from the sediment, makes it an excellent indicator of the level of oil pollution to which a soft bottom station has been subjected. This supports the value of M. balthica as an indi- cator of oil pollution, as suggested by Shaw et al. 1976, 1977, and supported also by Taylor and Karinen, 1977. 119 Since the reduced species are the most productive (highest P/B ratios, Cederwall, 1977), and are the most preferred food for the local fish fauna (Aneer, 1975), the change in energy flow patterns must have been drastic at the most heavily impacted station. Before the total effect on the local ecology can be evaluated, a better estimate of the heavily impacted area is needed. A sampling in June 1978, near (.less than 1 km from) station 20, but in slightly shal- lower water (31 instead of 32-33 m) showed an almost normal macro-and meiofauna. This fact indicates that the strongly affected area may be fairly small, or at least that the effect may be rather patchy in its distribution (and presumably much more pronounced on sedimentation bottoms than on transport or erosion bottoms). 6.4.2.2 Pontoporeia affinis reproduction An increased frequency of abnormal development or non-dif ferentiatinj eggs in Pontoporeia affinis seems to be a very sensitive indicator of toxic substances in the aquatic environment, since Sundelin (unpublished) has also found effects at very low levels of cadmium in the water (5 ppb) , Nevertheless, this effect is likely to be of only minor ecological importance, unless the area affected by oil is very large, since nearly all Pontoporeias seem to have left or died at the most heavily impacted station. This is an interesting example of so-called "effects monitoring" (ICES, 1978). In this case it seems that when the sub-lethal effect had reached a level that could be statistically demonstrated (increase of non-normal eggs from about 1 to 10%) , the macrofauna community had already changed so drastically, that the impact was immediately obvious and beyond the need for confirmation by statistical testing. The total community thus seems to have been a better integrator of environmental impact than a particular physiological parameter of a single species - even a highly sensitive one. This agrees with the suggestion by Mann and Clark (1978) that whole systems are better indicators of oil pol- lution than single species. 120 6.4.3 Meiofauna The meiofauna material suffers from lack of pre-spill data from station 20 (pre-spill samples are available but have not yet been sorted) All post-spill cores collected at station 20 are exceptionally low in both ostracods (Fig. 6.11) and other non-nematode meiofauna (Fig. 6.12), when compared both to station 15 and 8 other mud stations in the 25-45 m depth range (taken from a survey of the Askb'-Landsort area by Ankar and Elmgren, 1976; Fig. 6.14). Pre-spill macrofauna data shows station 20 to be a rather normal station (except for a trend of increasing biomass of Macoma balthica, due to eutrophication) , and there is thus no reason to expect it to have harbored an aberrant meiofauna. This would suggest that the extremely low post-spill meiofauna values are a direct oil effect. For the ostracods, with their protective shells, it is also possible that some recently dead animals were counted as live (since the samples were counted after preservation) . The dredge samples of large ostracods taken in February and March show a much higher proportion of live ostracods at the reference station 15 than at the spill station 20, where only few live large ostracods were found (Fig. 6.13). This is not directly comparable to the results from the meiofauna cores (where a 40 pm sieve was used) since only the largest ostracods were included, (0.5 mm screen), but it represents a much larger sample, and is therefore probably more reliable. There is thus some evidence of a high mortality of ostracods and other non- nematode meiofauna following the spill, but not enough to be entirely conclusive. The ostracod species concerned, and most of the other meiofauna, lack swimming ability, and could not have emigrated from the area . The continued low abundance of all meiofauna except nematodes, for 10 months following the spill, also indicates the low post-spill pop- ulations to be an oil effect, since a great development of the meiofauna would normally have been expected after the reduction of the competing macrofauna. For most of this period oxygen conditions were good, and contributed no alternative explanations for the low non-nematode meio- fauna at station 20. 121 The post-spill meiofauna samples from station 20 are similar in many aspects to the meiofauna community found after several months of oil addition (190 ppb average of No. 2 fuel oil) to MERL experimental ecosystems (MERL = Marine Ecosystems Research Laboratory, Graduate School of Oceanography, University of Rhode Island, USA. In press by Elmgren et al., also Grassle et al., 1978). Similarities include almost total dominance by nematodes after prolonged oil exposure and very rapid and drastic reduction in ostracod numbers following exposure. A detailed comparison of the two data sets will help in evaluating the usefulness of experimental ecosystems for studying and predicting the effects of oil and other pollutants in the marine environment. 6.5 Summary and conclusions Considerable amounts of oil reached the sediment within a week at the most heavily affected stations, as shown by sediment trap data (see Section 4). After one month, oil analyses of Ha coma balthica showed contamination with oil at several, widely separated stations. The macrofauna community responded drastically at station 20, and probable short-term effects were seen also at station 21. The vagile macrofauna, especially the amphipods died at or emigrated from the most affected station (No. 20). The few remaining gravid amphipods showed an increased frequency of abnormal eggs. No reduction in abundance or biomass was found in Macoma balthica or Halicryptus spinulosus . All meiofauna except the nematodes was drastically reduced at station 20 and a large kill of ostracods seems to have taken place relatively soon after the spill. In spite of these clear ecological effects, no Tsesis oil hydro- carbons could be conclusively demonstrated in the sediments, probably due to inadequate sampling methods. Neither the affected macrofauna, nor the meiofauna showed any evidence of recovering within the 9-10 month period alter the spill so far studied. 122 6.6 Suggested further studies The Tsesis spill clearly offers an unusual opportunity to monitor the recovery of a benthic soft bottom after moderate damage by oil pollution. Good pre-spill data are available for the macrofauna and can be obtained for the meiofauna. The following studies are planned: 1. To work up available pre-spill meiofauna samples from stations 15, 20 and 21 and more post-spill cores from stations 20 and 21. Station 20 has the highest priority. 2. To continue sampling stations 20 and 21 for meio- and macro- fauna until recovery at station 20 is complete. 3. To survey the affected area. This will be done in summer 1979 by means of a grid of about 40 van Veen grab samples, covering the suspect area. Macrofauna and large meiofauna (0.5 mm sieve) will be analyzed. This may locate areas where the impact on the benthos community has been even more drastic than at station 20. If so, then at lea.^t one of these should be included in the future sampling program (2 above). 6.7 Acknowledgement The expert statistical help of Ann-Sofi Matthiessen, Department of Statistics, University of Stockholm, was greatly appreciated. 123 6.8 References Addy, J.M., D. Levell and J. P. Hartley. 1979. Biological Monitoring of Sediments in Ekofisk Oilfield. Proc. Conf. "Assessment of Ecological Impacts of Oil Spills", Keystone Colorado, June 1978. Amer. Inst. Biol. 514-539. Aneer, G. 1975. A Two Year Study of the Baltic Herring in the Asko- Landsort Area, 1970-1972. Contrib. Asko Lab. Univ. Stockholm, 8: 1-36. Ankar, S. 1977. The Soft Bottom Ecosystem of the Northern Baltic Proper with Special Reference to the Macrofauna. Contrib. Asko Lab. Univ. Stockholm, 19: 1-62. Ankar, S. and R. Elmgren, 1976. The Benthic Macro- and Meiofauna of the Askb'-Landsort Area (Northern Baltic Proper). A Stratified Random Sampling Survey. Contrib. Asko Lab. Univ. Stockholm, 11: 1-15. Atlas, R.M., A. Horowitz and M. Busdosh. 1978. Prudhoe Crude Oil in Arctic Marine Ice, Water and Sediment Ecosystems: Degradation and Interactions with Microbial and Benthic Communities. J. Fish. Res. Board Can. 35:565-580. Cederwall, H. 1977. Annual macrofauna production of a soft bottom in the northern Baltic proper. In: Keegan, B.F., P. O'Ceidigh and P.J.S. Boaden (eds.): Biology of Benthic Organisms. Eleventh Europ. Symp . Mar. Biol., Galway, Oct. 1976. Pergamon Press, Oxford. 155-164. Cederwall, H. 1978. Long Term Fluctuations in the Macrofauna of Northern Baltic Soft Bottoms. I. 1970-73. Contrib. Asko Lab. Univ. Stockholm, 22:1-83. Cowell, E.B. 1977. Oil Pollution of the Sea. In: Johnston, R. (Ed.): Marine Pollution. Academic Press, New York, 1-729. Craib, J.S. 1965. A sampler for taking short undisturbed cores. J. Cons. Perm. Int. Explor. Mer. 30:34-39. Dixon, W.J. and F.J. Massey, Jr. 1969. Introduction to Statistical analysis. 3rd Ed. McGraw-Hill Kogakusha, Tokyo. 1-638. Dybern, B.I., H. Ackefors and R. Elmgren (Eds.). 197b. Recommendations on methods for Marine Biological Studies in the Baltic Sea. The Baltic Marine Biologists Publ. No. 1, 1-98. Elmgren, R. 1973. Methods of sampling sublittoral soft bottom meiofauna. Oikos, Suppl. 15:112-120. Elmgren, R. 1976. Baltic Benthos Communities and the Role of the Meiofauna. Contrib. Asko Lab., Univ. Stockholm, 14:1-31. 124 Elmgren, R. , G.A. Vargo, J.F. Grassle, J. P. Grassle, D.R. Heinle, G. Langlois and S.L. Vargo (in press). Trophic Interactions in Experimental Marine Ecosystems Perturbed by Oil. Proc. Symp . "Micro- cosms in Ecological Research", Augusta, Georgia, USA, November 1978. Elmgren, R., R. Rosenberg, A.B. Andersin, S. Evans, P. Kangas, J. Lassig, E. Leppakoski and R. Varmo. (In press). Benthic Macro- and Meiofauna in the Gulf of Bothnia (Northern Baltic). Paper given at 4th Baltic Symp. Mar. Biol., Gdansk, Poland, Oct. 1975. Prace Morsk. Inst. Ryb . Gdyni . GESAMP: 1977. IMCO/FAO/ UNESCO/ WMO/ WHO/ IAEA/UN, Joint Group of Experts on the Scientific Aspects of Marine Pollution (GESAMP), Impact of Oil on the Marine Environment. Rep. Stud. GESAMP (6): 1-250 Grassle, J.F., R. Elmgren and J. P. Grassle, 1978. Response of benthic communities in MERL experimental ecosystems to low level, chronic additions of No. 2 fuel oil. Internat. Council Explor. Sea C.M. 1978/E:33, Mar. Environ. Qual. Comm. , 1-27. ICES 1978. International Council for the Exploration of the Sea. Coop. Res. Rep. 75. Kajak, Z., K. Kasprzak and R. Polkowski, 1965. Chwytacz rurowy do pobierania prob mikro- i makrobentosu, oraz probo niezaburzonej strukturze mulu dla celow eksperymentalnych. Ekol. Pol. (B) 11:441-451. Krebs, C.T. and K.A. Burns, 1977. Long-term effects of an oil spill on populations of the salt-marsh crab Uca pugnax. Science 197: 484-487. Lehman, E.L. 1975. Nonparametrics . Statistical methods based on rank. Holden Inc. San Francisco, 1-457. Leppakoski, E.J. and L.S. Lindstrom, 1978. Recovery of Benthic Macrofauna from Chronic Pollution in the Sea Area off a Refinery Plant, Southwest Finland. J. Fish. Res. Bd . Can. 35:766-775. Mann, K.H. and R.B. Clark. 1978. Long-term effects of oil spills on marine intertidal communities. J. Fish. Res. Board Can. 35:791-795. Mclntyre, A.D. 1971. Deficiency of gravity cores for sampling marine meiobenthos and sediments. Nature 231 (5300), 260. Mclntyre, A.D. and K.J. Whittle (Eds.). 1977. Petroleum Hydrocarbons in t he Marine Environment. Cons. Int. Explor. Mer. Rapp P.V. Reun. 171, 1-230. Mustonen, M. and P. Tulkki, 1972. The Palva Oil Tanker Disaster in the Finnish SW Archipelago. IV. The Bottom Fauna in the Oil Polluted Area. Aqua Fennica 1972, 137-141. 125 Ockelmann, K.W. 1964. An Improved detritus-sledge for collecting meiobenthos Ophelia 1: 217-222. Percy, J. A. 1977. Responses of arctic marine benthic crustaceans to sediments contaminated with crude oil. Environ. Pollut. 13:1-10. Sanders, H.L. 1978. Florida Oil Spill Impact on the Buzzards Bay Benthic Fauna: West Falmouth. J. Fisn. Res. Bd. Can. 35:717-730. Shaw, D.G., A.J. Paul, L.M. Cheek and H.M. Feder, 1976. Ma coma balthica: An indicator of oil pollution. Mar. Pollut. Bull. 7: 29-31. Shaw, D.G., A.J. Paul and E.R. Smith. 1977. Responses of the clam Ma coma balthica to Prudhoe Bay crude oil. Proc. 1977 Oil Spill Conf. Am. Petroleum Inst. Publ. 4284, 493-494. Taylor, T.L. and J.F. Karinen. 1977. Response of the clam Ma coma balthica (Linnaeus), exposed to Prudhoe Bay crude oil as unmixed oil, water soluble fraction and oil-contaminated sediment in the labor- atory. In: Wolfe, D.A. (ed.). Fate and Effects of Petroleum hydrocarbons in marine ecosystems and organisms. Pergamon Press, Oxford. 229-237. Thiel, H. , D. Thistle and G. Wilson, 1975. Ultrasonic treatment of sediment samples for more efficient sorting of meiofauna. Limnol. Oceanogr. 20:472-473. Vandermeulen, J.H. and D.C. Gordon Jr. 1976. Reentry of 5-year-old stranded bunker C fuel oil from a low-energy beach into the water, sediments and biota of Chedabucto Bay, Nova Scotia. J. Fish. Res. Bd . Can. 33: 2002-2010. Winberg, G.G. (Ed.), 1971. Methods for the Estimation of Production of Aquatic Animals. Academic Press, London, 1-175. 126 7. Impact of Oil on the Littoral Ecosystem CHAPTER 7: IMPACT OF OIL ON THE LITTORAL ECOSYSTEM I Introduction (Mats Notini ) When an oil spill occurs in coastal regions, littoral communities are often severely damaged (Southward and Southward, 1978; North et al., 1965; Blumer et al., 1971). However, as Michael pointed out in 1977, more studies of long-term and low-level effects of oils on basic com- munity processes are needed. The degree and duration of the injuries vary depending on the quantity and quality of the oil reaching the shore line. The clean-up techniques employed when removing the oil may also significantly affect duration and degree of damage. The residence time of the oil in the littoral system is dependent on the energy input in the area and mechanical energy (e.g., wind and wave action, presence of ice) is the single most important factor (Owens, 1978). The Tsesis ran aground in shallow, narrow waters and large amounts of the oil could not be prevented from reaching the nearby shores during the first hours and days after the accident. Therefore, extensive effects on the littoral communities could be predicted. On the second day following the accident (October 27), quantitative "pre-spill" sampling of the Fucus fauna was made at four as yet unaf- fected stations (Section 7.2). Three of these stations were later hit by the oil spill. Sampling and studies of the effects of the oil on these stations and three complementary stations were repeated at inter- vals during the first year following the spill. Another type of study carried out in the littoral zone at the same seven stations is reported in section 7.3. Here, the fauna and flora of the typical vegetation belts (i.e. Ceramium, Fucus and red algal belts) and Mytilus belts along the bottom slope were sampled according to the technique described by Dybern et al. (1976). With this method not only the plants themselves but also the animals dwelling in the algae and those living on the bottom below are sampled. This sampling was carried out in November 197-7 and June 1978. 129 The third type of study carried out in the littoral zone concerned in situ measurements of community metabolism according to the method described by Guterstam, 1977 (Section 7.4). This investigation was carried out during the acute phase of the accident. 7.2 Effects on Fucus macrofauna (Mats Notini) 7.2.1 Introduction The extensive archipelagos of the Baltic cover about 6% of its surface area. The bladder wrack Fucus vesiculosus is the dominating seaweed of the archipelagos all around the Baltic. There is no question as to the central role played by this alga in the ecological system of the Baltic sea. The net production of the bladder wrack in the area of Asko has been estimated for September to be about 20% of the entire plant plankton production. The annual produc- tion of the seaweed is probably higher, since macroalgae grow also when the plankton biomass is low (Guterstam, 1977). It has a maximum density at a depth between 0.5 and 2 m. This zone contains a great variety of ecological niches and is probably the most diverse and productive habi- tat in Baltic shallow waters (Jansson and Wulff, 1977). More than 70% of the macroorganisms of the Baltic sea occur at one time or another in this belt (Haage, 1969). The food chains of about 50 species of fish and 40 species of birds run through this area (Jansson, 1974). In the enclosed Baltic sea and its extensive archipelagos the diverse ecosystem of the Fucus belt is never far away. Therefore, any major oil spill in this area will reach this system within hours or at the most a few days. A recent study indicated drastic and long-term effects of an oil spill in this system (Notini, 1978). Almost the entire fauna belonging to the Fucus zone was wiped out and recruitment was found to take several years. This spill occurred at the same season of the year (October 1970) about 30 km northeast of the Tsesis grounding. 130 7.2.2 Materials and methods Quantitative samples of the Fucus belt macrofauna were taken at 7 stations in an area 2 to It) km from the Tsesis. The locations of the stations and the ship are shown in Fig. 7.2.1. Three of the stations (A, B and C) are located on the west shore of the island Toro. I'hese were the she-res first hit by the oil spill, on the day after the accident (October 27). The two stations D and E were reached by the oil after approxi- mately 5 to 10 days, respectively. Stations F and G are both situated within 2 km of the grounding place. F is located on the small island of Talloren east of Tsesis . Although the oil spill during the first days drifted towards that island most of the visible oil passed it on both sides. Station G north of Tsesis was never visibly oiled but on some occasions slicks drifted close bv . The samples were taken by the so-called plastic-bag method. A diver slipped a plastic bag over a randomly chosen Fucus plant at the selected location. The water was strained off and the bag with its content of algae and animals was transported to the laboratory for deep freezing. Five samples were collected on each sampling occasion. The individual samples were later thawed and analyzed by standard methods. Thus, the composition and biomass of the fauna, the distribution of sizes, the growth of the algae, and other items can be studied. The preliminary results presently available are based on a first inspection of 104 of the total 212 samples (Table 7.2.2.1). So far the animals in these samples have been counted and classified into sys- tematic groups. Arithmetic means of density of the normally most abun- dant groups are given, whenever possible with 95% confidence intervals. During the first year following the spill Mytilus edulis were collected for oil analysis at the same 7 stations. 7.2.3 Preliminary results A drastic decrease of the total Fucus macrofauna took place along the shore that was first hit by the oil spill (on October 27). During the following two weeks the arithmetic means of the density figures were 131 I ?.l . " - v7'c ^5 ^ V| V « ,S. I» 7? ^ I » Aspskarsgr /• GjlkluSb 1*- ' ' . *» J» B 12 1' n i > la. « jo J5 87 " St. \ ^^•Marai Wpelgam ^ w 7 ^ 79 )j\$ k\>op ■ .1 t KroJrsk .! * in — W M 7 SiT* '—- ~/''\ '" S12 -- ivftvy*"" AimfV" \ \ •'« » ' ,\' /v 1. . ?A\ T " ' JWV s 32 "1.2 rs Z2 *''"'" |WfcC,,\ I » » Kril.sk ■>■ ' \~}K4\^S\ I iToana.J/ • From! I M ^ , ..*'>V - * , ■ ! 1 f trrash./ , ya**™j 9 ,5>- " ■* . # .'h-t/rdfHjid C f~ { SvardSO / ^*^ V"**' / / IS : ) S.vrt.O"TLini I I ■' ' FAY U) 47': ■* / .-3 . s St 1 -1 " 67 (¥ ^* T n ft 7 30 1W1 5- ag mSa/i.A««« j Sttnru.\ SvfLhn \ ^. == l7Vtt77i^ftn«7 TLv\»^ » .'*ur,iu>/ _/ / <; ■ts\t,,"ll"n «? Sjtdifr 25 2£ TatLoren A* M \ Brnnium IS 31 fj V MO 2 37 JO * .it-* ro ho I men'* ^ J3 J7 T S E S I S »,° > ^ikf {*£**% n « » fj ai-aen i<2. 30/ 6 ** \\ _ ~ JRct< V -t'r * K j'r Jf r ji a ^ ® -1 -w ' V7-*««fe/7- 87 m a> •U M TorskJU\\ 20 \ *4 ▼ v '/stars V W , ^ is'/- V— ^ Table 7.2.2.1 Fucus Bag Sampling Number of samples taken Station : Date of sampling A 13 C D 10.27.77 (5)X (5)X (5)X (5)X 11.02.77 (5) 11.09.77 (5) (5) (5) 2(0) 5(0) 5(4) 11.15.77 (5) 12.14.77 (5) (5) (5) (5) 5(0) (5) 5(0) 5.02.78 5(0) 5(3) (5) 5(0) 5(0) (5) 5(3) 6.20.78 5(1) 5(0) 5(0) 5(0) 8.28.78 5(0) 5(0) 5(0) 5(0) 5(0) 5(0) 5(0) 10.30.78 5(0) 5(3) (5) 5(0) 5(0) (5) pre-spill samples ( ) number of samples examined 133 only 8-10% of the pre-spill situation at stations A and C. Station B between these two stations was probably affected in the same way (.Fig. 7.2.3.1). During the same period no such decrease occurred at the "reference" Station G. Station D, which was hit by the oil four days later, showed a possible decrease in magnitude of 40-50% although the variations in the samples were high. Samples from stations F and E have not been sorted yet, but observations during diving operations in the area indicated less acute damage compared to stations A, B and C. In spite of the initially heavy degree of oil pollution, a sig- nificant recolonization of the Fucus fauna had already started in the middle of December 1977 at Stations A and C. At Station C the total number of macrofauna specimens in October 1978 was of the same order as in October 1977 before the oil hit the station. At Station G also, the "reference" station, the situation in October 1977 and 1978, respective- ly, was very much the same. The process of recolonization seemed to be slower at Station B and possibly at Station D. The crustaceans Gammarus spp., Idotea spp . and Iaera spp . (Fig. 7.2.3.2, 7.2.3.3 and 7.2.3.4, respectively) were all drastically reduced by the oil. The specimens of the amphipod Gammarus spp. were sorted into two length classes, > 10 mm and < 10 mm (Fig. 7.2.3.2). The pre- liminary results show no differences in the effect of the oil on these two groups. In November 1977 Gammarus spp. was totally missing or significantly reduced at all examined stations hit by the oil (Stations A, B, C and D) compared to the pre-spill situation in October. But a recolonization had already started in December 1977 at stations A and D. The isopods Idotea spp. and Iaera spp. (Fig. 7.2.3.3 and 7.2.3.4) were not totally missing in the November samples, but individuals remaining were very few. At station B Iaera spp. was completely missing both in December and in May, half a year after the accident. Recolonization by Idotea spp. at the same station seemed likewise to be a slow process. However, in October 1978, one year after the Tsesis ran aground, a considerable recolonization of both species had taken place at station B. 134 +J si •H c 3 >. u 3 u 3 PL, On o o S-i a 03 D C a) £ 1000 r-i-i OCT NOV DEC MAY J UN n = 1 AU 6 OCT 1000 B r^-n^E-n ,-£-, NOV DEC MAY n=3 AUG OCT n=3 1000 ir -£ OCT 2000 D NOV DEC MAY JUN AUG OCT i 1000 OCT NOV NOV DE :c MAY JUN AUG OCT - NOV DEC MAY AUG OCT 1000 f i- i OCT NOV n=4 DEC MAY n = 3 JUN AU 6 OCT Fig. 7.2.3.1 Total number of macrofauna specimens in Fucus samples first year following the spill. _[ = 95% confidence interval for population means. 135 50 I i. 37 5 JUVENILE 0 l OCT NOV DEC MAY JUN AU G OCT +J A en ■H 0) U M U 3 Di O O rd TJ' •H > •H TJ C ■H o QJ JQ E 2 40 - B 80 50 50 0 0 4^ /Vrf~ NOV DEC fe OCT NOV 100 -\\ / V* 'A± iid_ OCT NOV NOV NOV L I* OCT NOV n = 4 MAY n=3 AUG OCT n=3 3M. \ ■ 1 I h DEC MAY JUN AUG OCT DEC MAY JUN AUG OCT :33 i DEC MAY AUG OCT ft M * DEC MAY n=3 JUN AUG OCT Fig. 7.2.3.2 Number of Gammarus spp. in Fucus samples first year following the spil = 95% confidence interval for population means. r = total number adults > 10 mm I = juveniles < 10 mm 136 100 +J x; tn ■H O 3 >i M O o o U a CO H ca 3 TS ■H > •H T3 C •H m o M 0) X! e 2 OCT 0.9 NOV DEC MAY JU N ns1 AUG OCT 250 - B 7.7 2.2 10.8 NOV DEC 250 - OCT 20 - D OCT NOV NOV 40 - NOV 100 - I- d OCT NOV MAY n=3 AUG OCT n=3 11 cd£ NOV DEC MAY JUN AUG OCT DEC MAY JUN AUG OCT i DEC MAY AUG OCT ± DEC MAY n^3 JUN AUG OCT Fig. 7.2.3.3 Number of Idotea spp . in Fucus samples first year following the spill. [ = 95% confidence interval for population means. 137 400 -_ s: &> ■H 1 >i en o D N Cn o o •H > ■H C o 0) XI 6 2 OCT NOV DEC 25 B i NOV DEC 100 r-3=- rn i OCT NOV DEC 500 D OCT NOV NOV DEC 400 NOV DEC MAY J UN AUG OCT n=1 0 MAY n=3 AU6 OCT n=3 MAY JUN AU 6 OCT r^ MAY JUN AUG OCT MAY AUG OCT 200 - G OCT NOV n=4 DEC MAY n=3 JUN AUG OCT Fig. 7.2.3.4 Number of Iaera spp. in Fucus samples first year following the spill. = 95% confidence interval for population means. 138 The dominating bivalve in the area, Mytilus edulis , showed great fluctuations in the Furus samples, both within a sample set and between the sets (Fig. 7.2.3.5J. However, a decrease in density figures in November compared to October due to oil was found. During the same period no such decrease occurred at Station G. The • ffects are there but closer analysis of the collected data is needed. When the My til us edulis from stations C and G are sorted into twyo groups (> 5 mm and 5 mm), comparison of these size groups strongly indicates a mortality of small individuals (< 5 mm) at Station C (Table 7.2.3.1). The abundance of Theodoxus f luviatilis , the dominating gastropod i n the area, also decreased significantly during the first months following the spill (Fig. 7.2.3.6), but at station C recolonization was very slow. In October 1978 the mean density figures were still significantly Lower than in October 1977. 7.2.4 Discussion Unfortunately, sorting and examination of Fucus samples is very time consuming. At present 49% of the collected Fucus samples have been inspected. In spite of this the available data presented here strongly indicate drastic effects on the Fucus macrofauna in the area. The abundance of all macrofauna species, with the possible exception of the barnacles Balanus improvisus, decreased during the acute phase at sta- tions affected by the oil. Comparison with the reference station G on the island of Fifong shows no such decrease there during the same period. The degree and duration of the damage varied at the different stations. From the results available, station B and C were probably the stations most affected, followed by station A. Station D showed a smaller degree of acute effect and a preliminary look at the samples from station E shows the same type of results. This may be explained by the fact that the oil reached these locations 5 to 10 days after the oil spill occurred. Therefore, this oil had been weathered for a longer period of time compared to that at stations B, C and A. Both these stations (D and E) are situated in shallow bays with low water exchange. They are the most protected of the stations studied here. Therefore the 139 200 100 A i OCT NOV DEC MAY JUN AU6 OCT -p en ■H 0) 3 >i M tfl i o o u 0) (0 Tj ■H > ■H TJ C ■H QJ e 2 100 - B NOV DEC 100 - OCT NOV DEC 1000 D OCT NOV NOV DEC 1000 - NOV DEC 400 - OCT NOV DEC MAY n=3 MAY MAY MAY i MAY n=3 £ AU6 m OCT n=3 JUN AUG OCT JUN AU 6 OCT AUG OCT JUN AUG OCT Fig. 7.2.3.5 Number of Mytilus edulis in Fucus samples first year following the spill. [ = 95% confidence interval for population means. 140 Table 7.2.3.1 The Percental Distribution of Mytilus edulis in 2 Size Classes at 2 Stations Date Station C Station G > 5 mm < 5 nun 10.27.77 71.6 28.4 11.09.77 99.2 0.8 12.14.77 100 0 05.02.78 85.6 14.4 10.30.78 90.8 9.2 > 5 mm < 5 mm 44.2 55.8 38.9 61. 1X 81.6 18.0 18.4 82.0 xx XX based on 4 Fucus samples based on 3 Fucus samples 141 -p Cn ■H < M T) U| fa tT> o o 0) ■ m H ■H > •H c •H 4-1 o M CD 500 - A -£ 2.0 OCT NOV DEC MAY T JUN n=1 AU G OCT 50 - 0.8 B -L NOV DEC 250 OCT NOV 250 D OCT NOV NOV 50 - NOV OCT Fig. 7, NOV n=4 MAY n=3 AU6 OCT n=3 T 1 0 0.6 HH r-i-i DEC MAY JUN AUG OCT .-in -£| -*i ■ ■■ > DEC MAY JUN AUG OCT I DEC MAY AUG OCT • 250 - T r^-i 3.8 G 1 DEC MAY n = 3 JUN AU G OCT 2.3.6 Number of Theodoxus f luviatilis in Fucus samples first year following the spill. = 95% confidence interval for population means. 142 long-range effects may be of the same magnitude as at the other stations, as the residence time of the oil in the littoral system is dependent on the energy in the system (Owens 1978) . The relatively fast recolonization of Station A may be explained by the fact that tins station was exposed to oil during a comparatively short period of time. Due to a change in wind direction on October 28 the drift of oil towards shore stopped. Thus, this station was exposed to the drifting oil spill for less than 24 hrs. In December 1977 a significant increase of most faunal species had already occurred at station A. Only one genus, Iaera, did not increase during that period. This may be explained by the low mobility of these small animals. At Station B, in the center of ttie polluted area, recolonization of this species had not started in May 1978. Crustaceans are without doubt sensitive to oil pollution (Notini and Hagstrom 1974; Linden, 1976; Notini, 1978) and many of them must have died during the acute phase of the Tsesis oil spill. The results from this study indicate that the recolonization of these species to a great extent is due to a horizontal migration from the unaffected areas. The early recolonization of the molluscs was, however, largely dependent on the vertical recolonization by surviving individuals. These were narcotized during the acute phase of the spill. By wave action they were swept down from the Fucus plants to the bottom. Later, the surviving individuals recovered and reentered the Fucus . As indi- cated in Table 7.2.3.1, the mortality among small Mytilus edulis seemed to be higher than that among larger individuals. Similar observations have been made in previous studies (Notini, 1978). Bivalves have been found useful for monitoring petroleum input since they reflect the concentration and relative amounts of different hydrocarbons in the water (Lee, 1977). They are able to bioaccumulate , but cannot metabolize hydrocarbons in their tissues. Thus, the Mytilus samples from the different stations in this study are of great interest since they make it possible to estimate dose and response data in situ as well as the background oil contamination before the spill. These 143 preliminary data indicate Station C to have had the highest concen- tration of oil in water during the acute phase. But the samples also indicate relatively high amounts of aromatic hydrocarbons in the tissues of My t i 1 li s from Station G. Together with data from sediment traps and Ma coma halthica , this shows that Tsesis oil must be considered widely spread in the area. Station G can thus not be considered as a "non- affected" station, even though the samples of the Fucus fauna showed no clear reduction of the fauna. The data presented here clearly demonstrates drastic effects on the animal life of the Fucus community. On the other hand recolonization at several stations started soon after the acute phase. 7.2.5 References Blumer, M. , Sanders, H.L., Grassle, J.F., and Sass, J. 1971. A small oil spill. Environment 13(2): 1-12. Dybern, B.I., Ackefors, H., and Elmgren, R. (Eds.). 1976. Recommenda- tions on methods for marine biological studies in the Baltic sea. Baltic Marine Biologists Publ. 1: 1-98. Guterstam, B. 1977. An in situ study of the primary production and metabolism of a Baltic Fucus vesiculosus community. In: Keegan, B.F., P. O'Ceidigh and P.J.S. Boaden (Eds.): Biology of Benthic Organisms. Pergamon Press, Oxford, 311-319. Haage, P. 1969. Bl9st§ngsbaltet . Zoologisk Revy 31:21-22. (In Swedish). Jansson, A.M. 1974. Community structure modelling and simulation of the Cladophora ecosystem in the Baltic sea. Contrib. Asko Lab. Univ. Stockholm 5:1-129. Jansson, B.O. and Wulff, F. 1977. Ecosystem analysis of a shallow sound in the northern Baltic - A joint study by the Asko group. Contrib. Asko Lab., Univ. Stockholm 18:1-160. Lee, R.F. 1977. Accumulation and turnover of petroleum hydrocarbons in marine organisms. In: Wolfe, D.A. (ed.). Fate and effects of petroleum hydrocarbons in marine organisms and ecosystems. Pergamon Press. New York, 60-70. Linden, 0. 1976. Effects of oil on the amphipod Gammarus oceanicus . Environ Pollut. 10:239-250. 144 Michael, A.D. 1977. The effects of petroleum hydrocarbons on marine populations and communities. In: Wolfe, D.A. (ed.) Fate and effects of petroleum hydrocarbons in marine organisms and eco- systems. Pergamon Press, New York. 129-137. Notini, M. and Hagstrb'm, A. 1974. Effects of oils on Baltic littoral community as studied in an outdoor model test-system. In: Marine Pollution Monitoring (Petroleum) Symposium and workshop. Gaithersburg, Maryland, NBS Spec. Publ. 409, 251-254. Notini, M. 1978. Long-term effect of an oil spill on Fucus Macrofauna in a small Baltic bay. J. Fish. Res. Board Can. 35 (5) : 745-753 . North, W.J., Neushul, M. Jr., and Clendennins, K.A. 1964. Successive Biological changes observed in a marine cove exposed to a large spillage of oil. Symposium Commission International Exploration Scientifique Mer Mediterranee , Monaco, 335-353. Owens, E.H. 1978. Mechanical dispersal of oil studies in the littoral zone. J. Fish. Res. Board Can. 35(51:563-572. Southward, A.J. and Southward, E.C. 1978. Recolonization of rocky shores in Cornwall after the use of toxic dispersants to clean up the Torrey Canyon spill. J. Fish. Res. Board. Can. 35(5) :682-706 . 145 7.3 Effects on the phytal ecosystem (H. Kautsky) 7.3.1 Materials and Methods Seven stations were chosen to represent the entire area contam- inated by the oil spill (Fig. 7.2.1). Most stations were placed in coves as it was expected that these would hold the oil for a longer time and the pollution effect would be higher and easier to detect. In some cases the oil was, in fact, forced into the coves with the help of spill-booms. All seven stations, including a reference station (G) with no visible oil spill, were sampled in November 1977 and resampled in June 1978. From the June sampling only 3 stations have been sorted (B, D and G) . Sampling was done by SCUBA divers, using the technique described in Dybern et al. (1976) and by Jansson and Kautsky (1977). The vegetation coverage and the Mytilus edulis coverage were estimated visually. The vertical extent of each identified belt was noted. Within each zone, quantitative samples were taken at random. In November, the sampling sites were marked with bricks; in June, random sampling was made in the vicinity of these bricks in order to facilitate comparison between November and June samples. Square frames with a side of 15, 20 or 50 cm were used depending on the kind of vegetation dominant in each belt. The samples in November were sorted and dried shortly after collection; in June the samples were frozen and sorted later. The samples were analyzed for species composition, abundance and 1S£ 2 2 biomass. The results are given in individuals per m or in g dry weight per m' 7.3.2 Results 7.3.2.1 Field observations November: At the most contaminated stations B, C and D (see Fig. 7.3.1) no free-swimming animals could be observed. At location B an oil smear was identified on Mytilus edulis down to a depth of 4 m. 146 CO s^'' C\ '\ i^v co -/ '- ,\~ •u to ' '. x" »-V \ co e „ \ "^ — ■>'! 1 U- o CO 00 -H M 0) ^1 X-" " \ /*_ *- 1 ! \ /'/ s C ^H i •* ^ ^~ V •H D. -O ^ E C a, co co £ en *&-: ~ -' , re o> . ^ \ * ' - A co u ^ \ j' '~r~ |u •- c E 00 m vy * O r-- td ^lr (F) fr June 19 n, abun CO o 3 -a -h o C 4-1 3 cfl -H Pu CO r~- 0 •U r^ a I C on E co — i O V /-^ Jj - — - C_! 01 CO - ^j: (l) a E -H 15 coi ai o 0 S-j > - Oi ^c 0 o c u ■H 0 ^r ■v CO r-H CO w re U C TD — *T 3 I. O 0> X 11 S-< -H N 0 rt O 4J >, "0 >-J u-i co i— I 0 V X H . 4J co rc P CO CO C 4-1 Cfl H 3 01 0) CO > u E re 0) 01 a) ra (D Bi CO S u CO O .« 3 co _, *— „ „ *""! « « . to CO C (0 0 o u (0 3 c 3 0 2 CC [A u O 00 •H CJ 0) D V w wj pK "^ ^ 01 u - en 10 CO 10 6 Sc Cj u V rC 4_i CO to to CO > O H IIC + 147 June: The sulphur bacterium Beggiatoa , which is an indicator of reduced bottoms, is not uncommon in the area, especially in depressions with stagnant water, often at the bottom of the littoral slope. At the oil polluted stations, Beggiatoa covered greater than normal areas even on flat bottoms in June 1978. A higher frequency of Mysidae could be observed at the reference station G and around the Asko Laboratory (adjacent area) than at contaminated stations. A peculiar growth of the tips of Fucus vesiculosus was also observed at station B and in lower frequency at Station C. It looked as if young plants had settled on the old degraded plant tips. On the shore at station B, a beach clean-up was carried out in June, causing a light oil film on the surface water. Samples taken on the deep Mytilus bottoms (8 m depth) visibly contained oil. The Cladophora belt was a bit broader in June, probably due to low water during spring. 7.3.2.2 Calculations from collected data November: A summary of biomass and frequency of dominating animal groups in the Cladophora and Fucus belt in November is made in Table 7.3.1. In some vegetation belts at the most contaminated stations, animal species groups, common at the reference station, were absent (Table 7.3.2). The frequency of vagile (and semisessile) forms was very low at stations B, C, D, E and F, probably as a direct response to oil contamination. The mussel Mytilus edulis dominated the biomass in the entire area. At the reference Station G about 20% of the total biomass in the Fucus belt consisted of other species. The vagile forms con- tributed only a few per cent. In the Cladophora belt about 40% of the total animal biomass consisted of vagile forms. At all other stations Mytilus together with Balanus improvisus dominated the fauna biomass totally, particularly at stations B and F. The vagile forms played a minor part. June and comparisons with November: The dominating plant species from three vegetation belts are listed in Table 7.3.3. Only five spe- cies dominated the biomasses in the specific zones. Cladophora glomerata replaced Ceramium tenuicorne in the shallowest zone (C), and Pilayella 148 rvj rsi E en E <~s i — o -~ r- -c u. -C c -j x ^-i r-~ o r- c c — u C 1. flj c ■a .c c e 3 (13 O z * A3 ffl m >}j2 3Z OQ e: > u 0 c o 4-1 4-1 ar '.1 n ■r-t o '-. a. O — .u O -C -a c *J E OJ H «3 i— 1 ~—A Z £ fl W £1 (fl J O C/3 H CU 5-S *J +1 m 1 ^ u w R >» 3 (0 (a (J i-( 3 0) — u- C_> Ph — < a* .j u -c — . E -c 5 V- -H OIU.IU1 «J c -C o o Cu -C •r* nj i-i a. u ■H c c -r-l CO X-l E o ui OJ 1— 1 (0 O ■r-i o rg E — 1 1— 1 )-i — 1 :* T w CD 3 4-> E (J o •o ^ c (L -C 3 3 ns w Z a u [IE] t*H I 152 r-v TO O x: o. o T3 TO U CU e > 0 4: .5 « 4-1 c •H w r-4. TO 6 •H 2 0 O u c TO CO >* 3 0) 00 >H ^s c •H ■H 4-1 S-i 4-1 >^ 0 TO s 4-1 C •H + -; 6 0 E en -0 3 • ■H r-~ M-i E O re • u 00 CO 01 •H CO u fc TO B T3 •« T3 y— N • C En 00 TO w r^ ON 0> CO 1 — 1 00 3 TO U CU 4-1 3 c C Pn a cu >-) 0 #■ M -^ T3 0) c_> C PM -~- TO CM ro r~- 00 •H £ * 153 o — O — U-) t ■£) t r O I rH c in en en a; l-i cc CD C d) £ j:i £■ o TJ U) QJ 0) i-l 4-1 CU i-H rO ca "J U 4-) -C •^ x: QJ .c H > H CO c 3 •-> T3 c CO r^ Oi i-i 0) XI 5 ai > o CN oo •H tn 01 01 CO C E c o C 0) •H •H •H C 4-1 .* CO c cfl 10 o c JJ 14-1 o •H 4J CO 01 u a c cfl X a, o u 0) CO CM 5 •H 1-1 (0 Vj 01 0) CO ^H •E 0 e ex •1-1 4-J e 00 1-1 0 cfl ~ >_i u > U-l 0 en o CI Oi r^ CD c 4J tH t ■H CO oo co m ■H •H Oi E c •H in -a r-1 c 10 a 3 e 0) a 0 ■H (0 co a n c ■a a o> (0 •rH ro if) U a) ta 01 re £ 10 ■h 1-1 c ■P u 0) •H g 0 1) 0) Oi <0 T3 (0 to re O l-l ►o E-i > 155 The percentage of abundance and biomass of dominating and vagile species is shown in Tables 7.3.5a and b. Gamma rus spp. and Iaera spp . had a very low share of the abundance in November. In many vegetation belts they were totally absent, for example at station B. In June, Iaera was still missing at that station, except in the Ceramium + Mytilus belt, where a single individual was found. In June, gammarids occurred in high abundance at all stations (Table 7.3.3 and 7.3.5a). Most of the gammarids were juveniles. Only 8%"-of the samples contained adult individuals at Station B. Correspond- ing frequencies for stations D and G were 75% and 80%, respectively. 7.3.2.3 Comparison with data from oil analysis of Mytilus edulis The oil content of Mytilus edulis at different times of the year is given in section 11.3.1 and Tables 11.1 and 11.2. The analyses showed a low level of oil before the contamination (10/27/77), and a drastic increase after the spill. The oil content then decreased during the year as shown by successive analyses. The high mortality/absence of all vagile forms mentioned above at the contaminated stations in Novem- ber corresponds well with the high oil content analyzed in Mytilus . The return of vagile forms indicates a healthier environment. This is also indicated by the decreasing oil content analyzed in Mytilus . 7.3.3 Discussion The vegetation, animal diversity and biomass for each vegetation belt usually showed higher values at the reference Station G, especially in November but also in June (Tables 7.3.1, 7.3.2, and 7.3.3). Station G may be considered to be a typical station for the area. No previous investigations in the surrounding area indicate that it would be extreme in any way (Haage, 1975, 1976; Jansson, 1974; Jansson and Kautsky, 1977, Kautsky, 1974; Wallentinus, 1976). The parallel work of Notini also corroborates this (section 7.2). No effect of the oil spill on the benthic macrovegetation was observed. The same observations were made in the Baltic by Notini (1978) and Ravanko (1972). They investigated accidents which happened at the same season, before the spring growth. 156 oj 00 91 > c o tH • 4J T3 ra ai C 4J ■h ra E o 4-1 T3 c c o ■* o 01 .- QJ U > •H 01 4J 00 H 10 10 4-1 c c •H 01 U r OJ H a en rH CO 01 r^ t 3 ■a c <0 t: 0) c JO 3 g XI 0> ra > 0 iH ss ra 4-1 c o •H *-i "J 14 OJ o 4J ra OJ 00 00 -H ra 4-1 4-1 '/: C OJ 01 > o c >J •H O) a to CM — » ^-t o -■ -C C E \0 ' r-H o ^-- o o o rg o sn-[T3AW snjEuiuiBo Bias] eaqjopi 157 CNJ i— ' 1 — 1 —i ■? -«-> o i— i o o o <—> in !>, Hi ^h si tj -a E sTrfpT^W snjeuiuiEQ eaaei eaipopi 15S The peculiar growth of Fucus observed at station B was probably an effect of the low water which exposed the Fucus tips to the air, causing the protective mucilage layer to dry out . This layer may prevent the Fucus plants from being damaged by contamination. The Fucus plants is rather resistant to light and heavy fuel oil exposure, as shown in outdoor laboratory tests (Ganning and Billing, 1974; Notini, 1978). Results from station B indicate a doubling of the Fucus biomass. This can probably be explained by the heterogeneity of the Fucus belt at that station. A very small change in the sampling site could change the results drastically. It is expected that the Fucus belt would not increase as much as the results indicate. The increase of Fucus biomass (40%) at station D (Fucus belt) might be explained in the same way. The increase of animal biomass in the Fucus belt at station B in June was caused mainly by increased numbers of Mytilus . These may be the same individuals which were removed and transported from the shal- lower situated Cladophora belt due to narcosis from oil contamination or through mechanical stress during the cleanup operations on the shore. It could also be due to the larger Fucus biomass sampled. Some crustaceans, which have a hydrophobic wax layer on their cuticle, are very sensitive to oil contact (Notini and Hagstrom, 1974). This may explain the drastic decrease of the crustaceans (vagile forms) at the oil-contaminated stations in November. The rapid recruitment of vagile forms from adjacent areas in the Baltic has also been observed by Pelkonen and Tulkki (1972) and Notini (1978). This is also indicated by the high proportion of young in- dividuals at the contaminated station. The lack of chironomid larvae at station B (Table 7.3.3) may be an effect from the oil spill as these organisms have proved to be sensitive to oil contamination (Bengtsson and Berggren, 1972). However, the sampling was too small to allow any definite conclusions. The results of the oil analysis from the reference station G are confusing. The high oil content in Mytilus is not correlated with absence of vagile forms as at the visibly contaminated stations. 159 This study has indicated a rapid recovery of the phytal system. The oil spill occurred at the beginning of a season of low activity in the phytal zone. The low temperature and ice cover from January to March minimize plant and animal metabolism and growth. Many individuals usually die during winter due to senescence. During these 3-4 months of low activity, before the spring growth started, parts of the remaining oil in the littoral were probably washed out and the toxic fractions diluted. Thus the oil spill did not affect the fauna and flora of this system as much as if the spill had occurred in the beginning of the growth season, in April to June. 7.3.4 References Bengtsson, L. and H. Berggren. 1972. The bottom fauna in an oil-contaminated lake, AMBIO 1: 141-144. Dybern, B.I., H. Ackefors and R. Elmgren. (eds.). 1976. Recommendations on Methods for Marine Biological Studies in the Baltic sea. Baltic Marine Biologists Publ. 1:1-98. Ganning B. and U. Billing. 1974. Effects on community metabolism of oil and chemically dispersed oil on Baltic Bladder Wrack (Fucus vesiculosus) . In: Beyon, L.R. & E.B. Cowell (eds.). Ecological aspects of the toxicity testing of oils and dispersants. Applied Science Publishers, Ltd., London. 53-61. Haage, P. 1975. Quantitative Investigations of the Baltic Fucus Belt Macrofauna. 2. Quantitative Seasonal Fluctuations, Contrib. Asko Lab. Univ. Stockholm. 9:1-88. Haage, P. 1976. Quantitative Investigations of the Baltic Fucus Belt Macrofauna. 3. Seasonal Variation in Biomass, Reproduction and Population Dynamics of the Dominant Taxa , Contrib. Asko Lab. Univ. Stockholm. 10:1-84. Jansson, A.M. 1974. Community Structure, Modelling and Simulation of the Cladophora Ecosystem in the Baltic Sea. Contrib. Asko Lab. Univ. Stockholm. 5:1-130. Jansson, A.M. and N. Kautsky. 1977. Quantitative Survey of Hard Bottom Communities in a Baltic Archipelago. In Keegen, B.F., P. O'Ceidigh and P.J.S. Boaden (eds.), Biology of Benthic Organisms, Pergamon Press, New York. 359-366. 160 Kautsky, N. 1974. Quantitative Investigations of the Red Algal Belt in the Asko Area, Northern Baltic Proper, Contrib. Asko Lab. Univ. Stockholm. 3:1-29. Notini, M. 1978. Longterm Effects of an Oil Spill on Fucus Macrofauna in a Small Baltic Bay, J. Fish. Res. Board Can. 35(5) : 745-753 . Notini, M. and A. Hagstrom. 1974. Effects of oils on Baltic littoral community, as studied in an outdoor model test system. In: Marine Pollution Monitoring (Petroleum) Symposium and Workshop. Gaithersburg, Maryland, NBS Spec. Publ. 409, 251-254. Pelkonen, K. and P. Tulkki. 1972. The Palva Oil Tanker Disaster in the Finnish S.W. Archipelago. III. The Littoral Fauna of the Oil Polluted Area. Aqua Fenn. 1972:129-139. Ravanko, 0. 1972. The Palva Oil Tanker Disaster in the Finnish S.W. Archipelago. V. The Littoral and Aquatic Flora of the Polluted Area, Aqua Fenn., 1972:142-144. Wallentinus, I. 1976. Environmental Influences on Benthic Macrovegetation in the Trosa-Asko Area, Northern Baltic Proper. I. Hydrographical and Chemical Parameters, and the Macrophytic communities, Contrib. Asko Lab. Univ. Stockholm. 15:1-138. 7.4 In situ respiration of three littoral communities near the Tsesis oil spill (Bjorn Guterstom) 7.4.1 Introduction In order to determine if the oil had affected the community meta- bolism in situ measurements in plastic bags were made on three typical littoral communities of the northern Baltic: 1. the Fucus vesiculosus community 2. the Mytilus edulis community 3. the "shallow soft bottoms" with Ma coma balthica and Hydrobia spp. as the dominating macrofauna components. 161 t .4. 2 Methods Part of the communities were enclosed in plastic bags (0 = 0.5 m, volume 30-70 litres, Fig. 7.4.1, details see Guterstom, 1977) using SCUBA diving. The oxygen consumption was measured with a YSI oxygen electrode on several occasions over a 24 hr. period. Experiments were run at the most contaminated stations and at a similarly exposed, "unpolluted" reference station. Further data from these stations are presented in sections 7.2 and 7.3. Due to failure of the Mytilus experiment at the reference locality, these results were compared with results from laboratory experiments. 7.4.3 Results and discussion The results from the three communities investigated show a typical picture with relatively low respiration at this time of the year (Novem- ber, Table 7.4.1). Only the Fucus communities at two oil polluted localities showed higher respiration than similar unpolluted localities (.Table 7.4.1). An increased respiration due to exposure to oil at increasing concentrations was found in outdoor experiments with F. vesiculosus from the northern Baltic (Canning and Billing, 1974). The shallow soft bottoms showed the same respiration at both localities. The same was found with Mytilus from oil polluted localities compared with mussels from unpolluted areas. At the oil polluted localities oil could be seen in the plastic bags after the incubation periods as it had floated up as small drops under the plexiglass covers of the plastic bags in all experiments. In June 1978 oil was still leaching out of the investigated sediments. Due to the low biological activity during the winter and the few replicates in each experiment, no significant difference in respiration could be found. As shown in Chapter 11 (Tables 11.1-11.4) and discussed in section 7.2.4, the "unpolluted" reference station was later found also to have been contaminated by the oil, even though not by visible slicks. Any effects which might influence the community respiration through changes in animal populations would therefore be expected to be found during the following summer and autumn. Notim (1978) found lower macrofauna populations at oil polluted Fucus communities of the northern Baltic compared to unpolluted communities. 162 50 cm Fig. 7.4.1 Plastic bag 1: buoy 2; plexiglass lid 3; stopper 4; upper ring 5; rubber band 6; plastic 7; lower ring (open) . 163 Table 7.4.1 In situ respiration of three oil polluted littoral communi- ties near the Tsesis oil spill compared with unpolluted communities in the same area. Reference station underlined. Locality (see Fig. 5.1.1) Date Temp. Respiration (°C) (mg 02 g dr.wt Biomass (g dr.wt) Fucus vesiculo- sus (1.5 m depth) D 1-2.11.77 8.0 D 2-3.11.77 8.0 G 2-3.11.77 8.0 B 14-15.11.77 6.8 B 14-15.11.77 6.8 G 14-15.11.77 6.8 0.29 0.38 0.16 0.07 0.17 0.04 79 Fucus 79 " 80 tt 43 ii 27 M 131 11 Mytilus edulis (2 m depth) D 1-2.11.77 8.0 0.10 237 Mytilus incl. shell D 2-3.11.77 8.0 0.06 72 B 9.11.77 7.8 0.09 176 Laboratc >ry 17.11.77 7.7 0.10 ± 0.0 n = 10 ind. (recalculated from Sec. 10.2) "Shallow so: ft mg _2 _ 1 0o m h Ind . m Macrofauna 2 (dr.wt. g m ) bottoms" (1 m depth) D 16-17.11.77 6.4 18. .4 4669 234 D 16-17.11.77 6.4 24 .5 14616 52 G 16-17.11.77 5-5 20 .9 7917 106 164 As oil is still present and is leaching out of the bottoms in- vestigated here, the respiration of these littoral communities is pro- bably influenced to some extent. 7.4.4 References Ganning B. and U. Billing. 1974. Effects on community metabolism of oil and chemically dispersed oil on Baltic bladder wrack Fucus vesiculosus . In: Beyon, L.R., and E.B. Cowell (eds.). Ecological aspects of the toxicity testing of oils and dispersants. Appl. Sci. Publ . Ltd. England. 53-61. Guterstam, B. 1977. An in situ study of the primary production and the metabolism of a Baltic Fucus vesiculosus L. community. In: Keegan, B.F., P. O'Ceidigh and P.J.S. Boaden (eds.). Biology of benthic organisms, Pergamon Press, Oxford, 311-319. Notini, M. , 1978. Long-term effects of an oil spill on Fucus macrofauna in a small Baltic bay. J. Fish. Res. Board Can. 35:745-753. 165 8. Impact of Oil on the Supralittoral Zone CHAPTER 8: IMPACT OF OIL ON THE SUPRALITTORAL ZONE 8.1 Damage to shore vegetation (Anders Lindhe) 8.1.1 Introduction This study was not begun until the middle of June and by then all the affected coastline including all the fine-grain sediment shores suitable for field study had been cleaned up. This was also true of the bay near Lisb'kalv which was supposed to be left undone. Accordingly, traces of damage by oil upon the vegetation were mostly masked by the mechanical effect of the cleanup. Any sites for studying the long-term effect of oil upon vegetation could, for the same reason, not be found. Since the cleanup on land was mostly mechanical, the effect of chemicals could not be studied. A rough estimate of the acute effects of oil on plants could, however, be gained by studying some non-cleaned areas in the Stockholm archipelago affected by oil from the ship Oktavius . The rest of the work was devoted to studies of the cleanup measures from a biological point of view. 8.1.2 Methods The field work consisted of visits to different oil-affected and cleaned-up areas during June, July and August. In early summer, sites in the Stockholm Archipelago (at Varmdolandet and some nearby islands), affected by oil from the Oktavius and Michail Kalinin oil spills, were studied. The Oktavius oil had been on the shore for about as long a time as the Tsesis oil, though it was of a slightly different type. The Michail Kalinin oil, thin diesel oil, had only been on the shore for a couple of weeks when the studies were made. Some fine-grain sand shores on Toro and Svardso, heavily affected by Tsesis oil, were also visited at this time. These sites were revisited at the end of summer when the entire coastline between Oren on southern Toro and Hoviksholmarna on Svardso were investigated on foot. The firm, "Sanerings Konsult", is thanked for valuable assistance with transport and information. 169 8.1.3 Results: Acute effects on vegetation In general the plants seemed to be astonishingly little affected by growing on or in close contact with heaps of oil on the shores. This impression is characteristic of all the areas and different types of oil studied. At places with a dense layer of oil, however, the plants showed frequent signs of abnormality or injury. It is, of course, impossible in any one instance to distinguish with certainty between effects caused by oil or, for example, by parasites or local variation in water supply. However, the following observations have been made several times and are, with fair reliability, oil-dependent. Filipendual ulmaria and Lysimachia vulgaris were very dwarfish when growing on soil heavily impregnated with oil. Seedlings of these grow- ing through a thick layer of oil also showed strong malformations. Deformities were also observed in Valriana officinalis and Tussilago farfara . Discoloration, reminiscent of water shortage, was noted in Festuca rubra , Agrostis stolonifera , Atriplix latifolia and Equisetum arvense when the plants were on or close to oil on the shore. Some specimens seemed less sensitive and Cirsium arvense was found on several occasions growing on thick heaps of oil without visible effects. 8.1.4 Some comments on the clean-up methods In the Torb'-Svardso area there are several different types of shore. Rocks, stone, gravel and sand, in places exposed to wave action, and fine-grain sediment shores with reeds in more sheltered bays. Rock dominated areas: The only vegetation are lichens and micro- scopic algae. No attempts were made to estimate how these were affected by oil. On these kinds of shores the oil, which soils the rocks with a more or less thick covering, is removed by spraying with water at high pressure, scrubbing with oil-dissolving chemicals or steam treatment, which makes the oil easy-flowing." All methods, however, only transfer the oil to the water. It is hardly possible to take care of and destroy all the oil on these shores and, instead take all possible measures to prevent the oil from reaching them. 170 Stones: These shores are less steep than the rocky ones and, for this reason, can hold more oil. The vegetation consists of sparse stands of plants rooted in the finer sediment between stones. The greater part of the oil can be collected by suction pump and spades after which a more careful cleanup takes place as described above for rocks. Stones, too contaminated for cleaning, can also be removed. One of the problems with this kind of shore is that some oil always per- colates to the gravel between the stones and is out of reach of cleaning. In time, this oil is likely to bleed and pollute the water below. Clean-up operations are difficult and very time consuming and so, if possible, the oil should be prevented from reaching these shores also. Gravel and sand: These shores are rare in the area. Stable parts often carry a complete covering of vegetation. If oil affects this, it is harvested and removed. Filthy sand and gravel are also dug up and carried away. A particular example of a sandy beach is Reveln near Oren on southern Toro. The entire point is made up of sand with gravel on the northern shore and fine sediment on the western side. The area is protected on account of the rich bird life in spring and autumn. The ground on the point is very sensitive to wear. Unfortunately, heavy vehicles have been used in connection with the cleanup operations and deep tracks, which will be slow to heal, have resulted. Also, the traffic across the point has not been properly channeled, which might have lessened the damage. It would have been best to arrange transport by boat. However, the cleaning of the beach proper is satisfactory and the re-visit in August showed that the shore vegetation was recovering quite nicely . Fine grain sediment: These shores are found in sheltered bays, and if ungrazed, are dominated by common reed. Being very level they can hold much oil. During the cleanup after the Tsesis accident, the oil was actively steered into such bays where it was collected by suction pump, and the oil saturated reeds were harvested and removed. Any remaining oil was raked together and destroyed. Several places like these were visited in June and re-visited in August. The impression was that the vegetation was very little damaged. The reeds recovering after 171 harvesting seemed completely normal and on re-visiting it was not always easy to distinguish oil affected and non-affected sites. Even the smaller species seemed to have recovered - for instance Myosotis palustuis and (.at Varmdo) the tiny annual Montia fontana . Thus clean-up operations on these shores seem to have worked very well. The oil was taken away from the area to be destroyed instead of being washed back into the sea and the cleaned areas seemed to recover fairly soon. 8.1.5 Concluding remarks No very significant oil-induced vegetation damage could be demon- strated in this study. One cannot however eliminate the possibility that some effects will show only after a considerable period has elapsed. What will happen to the oil that has been left in the soil despite the cleanup? How is it broken down and into what substances? Are any of these more toxic than the oil itself? Are some substances so slowly accumulated by roots and rhizomes that injuries will not show until much later? These and other important questions can only be answered by further studies including experimental field work. Cleaning operations must aim towards removal and destruction of the oil. Pollution of rocky and stony shores must for this reason be mini- mized by channeling the oil towards sheltered bays at an early stage when this is at all possible. This will also prove to be economically beneficial since cleaning of rocks and stones is very time consuming. Absorption of the oil using bark splinters and sowing of grass, which have been tried in some places, seem very doubtful methods from a bio- logical point of view since the oil will remain with unknown conse- quences. The results will at best give rise to unnatural systems with species poorly adapted to the gradients of shore salinity. 172 2 Effects on the supralittoral fauna (Maria Foberg) 2.1 Introduction The importance of having knowledge on the effects of an oil spill, not only in the water but also on the adjacent areas above the water- line, is quite obvious since few investigations have been carried out for this purpose, especially in the Baltic Sea. In order to obtain comparable samples the wrack bed was chosen as a sampling area as it was a biotope which occurred at several of the stations. 8.2.2 Materials and methods Three supralittoral stations situated close to stations B, C and D and one close to the reference station G (Fig. 7.2.1) were investigated during the first two weeks of August 1978, over nine months after the spill. On two occasions - August 2 and August 8 - six pit-fall traps containing water and detergent (used for decreasing the surface tension) were placed in the wrack bed at each station for 24 hours. At the same time two quantitative samples were randomly taken at each station with a frame (20 x 20 cm) so that 10-15 mm of the upper part of the ground material was included in the sample - making a total of 12 traps (10 at station G since two were lost) and 4 quantitative samples from each station. The samples were sorted (the quantitative first by hand and then with a Tullgren apparatus, as described in Backlund, 1945), determined to taxonomic group (family), in some cases to species, and counted. In those cases where a large number of spring-tails (Collembola) were found it was not possible to determine every individual. Instead a subsample was examined and the systematic groups recorded. A comparison between number of individuals and number of systematic groups at the different stations was made (Tables 8.2.1, 8.2.2). The number of individuals in the quantitative samples was recalcu- lated to 100 g wrack dry weight. All newly hatched isopods, which were presumably caught while still clinging to their mother, were left out of the calculations, but the numbers are given in Table 8.2.3 (and later in Table 8.2.6) . 173 Table 8.2.1 Occurrence of systematic groups and number of individuals in the pit-fall traps at the four stations. Figures after ± are standard error of mean. Average No Number Average No of Total No of Stn of ind/trap of traps syst grp/trap syst grp B 20±b 12 8±2 28 D 30±5 12 9±1 29 C 39±8 12 10±1 30 G 57±9 10 12±2 33 174 Table 8.2.2 Percentual distribution of the different groups of animals found in pit-fall traps at the four stations. The column "other" includes Orthoptera, Thysanoptera (Insecta) and Myriapods. Stn B Stn D Stn C Stn G (Norr (Lind- (Tistel- (Fifing) Skotskar) holmen) holmen) 1 % 1 t Insecta : Collenibola 2.1 24.2 4.1 3.5 Hemiptera 0 4.5 0.4 8.5 Hetereptera 0 0.2 0.4 0 Coleoptera, adults 5.9 4.2 6.6 3.9 larvae 0.7 0 3.9 0.7 Hymenoptera : Paras i tie 1.3 0.8 0.4 2.3 Formicidae 24.4 18.5 0.9 5.7 Apidae 0.4 0 0 0 Diptera : Brachycera 21.0 6.2 17.4 21.2 Nematocera 3.8 4.2 3.2 1.4 Crustacea : Porcellio scaber 23.1 22.8 6.7 1.9 Orchestia gammarellus 0 0 0.2 10.4 Arachnoidea : Araneae 6.7 12.6 54.7 39.2 Arcarina 2.5 0 0 0 Opiliones 0 0.6 0 0 Other 2.1 0.6 1.1 1.2 175 Table 8.2.3 Total number of individuals (x) caught in the traps at the four stations and percent (%) frequency of occurrence. Number of Traps Stn B 12 x % Stn D 12 x % Stn C 12 x % Stn G 12 x 1 INSECTA Collembola fam. Entomobryidae Poduridae Isotomidae Sminthuridae larvae Hymenoptera fam. Thysanoptera fam. Thripsidae Hemiptera Homoptera fam. Aphididae M Cicadellidae Heteroptera fam. Lygaeidae 1! , Scolopostethus sp. Coleoptera fam. Carabidae n , Pterostichus niger 1 ii , Harpalus sp. ii , Metabletus sp. ii Hydrophilidae , Cercyon sp . n Staphylinidae 1 n Silphidae, Thanatophilus sp . 9 ii Ptiliidae ii Scarabaeidae , Geotrupes sp. Elateridae Nitidulidae Coccinellidae Curculionidae (mostly Pterostichus niger) Ichneumonidae Braconidae, Syncrasis fucicola , Pemphredon lugubris Proctotrupoidae, Basalys sp . , Tricopria sp . , Codus sp . , Trimorus sp . Diapriidae, Diapria sp. 2 Pteromalidae , Urolepis maritima Formicidae, Myrmica rubra 3 , Formica fusca 4 , F. ruf a 5 , F. ruginodes 1 , Lasius niger 45 , Camponotus herculeanuro Apidae, Bombus sp. 1 17 25 3 25 16 42 1 8 1 8 17 17 25 25 8 67 65 100 8 17 13 17 1 8 92 8 9 33 10 8 33 9 20 11 50 6 42 2 2 17 17 42 6 70 40 3 17 9 50 14 67 10 50 1 8 1 8 11 50 3 20 3 25 2 17 0 17 7 40 1 8 1 8 1 8 1 8 1 8 2 10 17 67 4 40 1 8 4 40 9 17 1 8 3 1 2 1 1 1 30 10 10 10 10 10 1 8 6 30 2 8 8 50 4 33 1 10 17 50 176 Table 8.2.3 (cont'd) Diptera Brachycera fain. Dolichopodidae Phoridae 4 17 8 42 Pipunculidae " Syrphidae Sciomyzidae Ephydridae 8 33 , Ephydra macellaria alandica 1 8 " Agromyzidae Chloropidae Tachinidae Muscidae , Coenosia mollicula , Dexiopsis lacteipennis , Lispe tentaculata Anthomyiidae Scatophagidae , Scatophaga litorea 1 Nematocera fani. Corethridae Chironomidae, adults , larvae Mycetophilidae Cecidomyidae unidentified Orthoptera fani. Acrididae CRUSTACEA Isopoda Porcellio scaber, adults , newly hatched Ainphipoda Orchestia ganiraarellus ARACHNOIDEA Aranae fam. Linyphiidae 8 33 Lycosidae 8 42 Gnaphosidae, Hicaria sp. Acarina fam. Ixidae, Ixodes ricinus 6 17 Opiliones MYRIAPODA Chilopoda fam. Lithobidae, Lithobius sp . Diplopoda fam. Iulidae 2 17 CASTROPODA Stylommatophora fam. Arionidae MAMMALIA Insectivora fam. Soricidae, Sorex sp. X /o X /0 X ^ 5 25 45 83 80 80 3 25 2 17 2 20 1 10 1 3 17 4 20 22 75 8 42 18 83 24 60 1 8 1 8 9 c 8 1 10 1 8 1 10 2 17 2 1 17 8 1 1 8 8 7 20 2 17 1 8 1 8 2 17 1 10 1 8 1 8 4 25 1 8 1 8 11 42 9 5 42 8 3 20 4 33 2 17 1 8 3 30 3 17 2 17 4 17 2 20 1 8 2 17 3 20 55 100 81 92 31 83 11 70 81 8 1 8 59 70 26 67 171 100 205 100 18 50 84 92 17 60 1 8 17 1 10 20 1 10 177 The orders found were: Insecta: Thysanoptera , Collembola, Orthop- tera, Hemiptera, Coleoptera, Hymenoptera and Diptera. Crustacea: Isopoda (Porcellio scaber) and Amphipoda (Orchestia gamma re llus) . Arachnoidea: Araneae, Arcarina and Opiliones. Myriapoda : Diplopoda and Chilopoda. Oligochaeta: Plesiopora and Gastropoda: Stylommato- phora . The genera Pachydrilus and Enchytraeus (Oligochaeta) have not been taken into consideration and were left out in all calculations. This was due to the difficulty of obtaining reliable abundance estimates for these highly contagiously distributed animals. The estimated numbers are given in Table 8.2.4 and percent distribution in Table 8.2.5. 8.2.3 Description of the stations At station B and D there was a small belt of totally dry wrack only a couple of centimeters deep and 15 cm wide, which, according to Backlund (1945), could be characterized as a wrack string. The wrack consisted almost exclusively of Fucus vesiculosus with some Cladophora . At these two stations a few oil slicks could be seen on some stones but not in the wrack. Station B, one of the most heavily contaminated stations, was subject to cleanup in the middle of June 1978, during which time parts of the ground were dug up and turned over. At station C, also heavily contaminated, a rather large slick of oil was found in one of the quantitative samples. Here, the wrack accumulation was much larger, about 10-15 cm deep and 50 cm wide, con- sisting of decaying wet wrack. At station G, the reference station, the wrack bed was similar in size to that at C and consisted of decaying wet wrack. At this station there was a bed of reed adjacent to the sampling area, and as a result the wrack contained much material from Phragmites australiensis . 8.2.4 Results 8.2.4.1 Pitfall traps At station G there were more individuals and systematic groups in each trap as well as a higher total number of systematic groups found 178 Table 8.2.4 Occurrence of systematic groups and number of individuals in the quantitative samples at the four stations. Figures after + are standard error of mean. Average No of ind/lOOg Number Average No Total No Estimated No of wrack (dry of of syst grp/ of syst Enchytr/Pachydr per sample 200 250 2000 4000 Stn weight) Samples sample grp B 85+23 4 7+1 11 D 57+31 4 6+3 13 C 175+93 4 8+2 13 G 162+25 4 10+2 13 179 Table 8.2.5 Percent distribution of the different groups of animals found in the quantitative samples at the four stations. Stn B Stn D (Norr (.Lind- Skb'tskar) holmen) 1 1 Stn C Stn G (Tistel- (FifSng) holmen) % % Insecta : Collembola Hemiptera Coleoptera, adults , larvae 2.2 1.5 5.1 0.7 12.8 0 2.4 0 30.9 0.4 2.4 0.4 42.9 0.2 6.7 0.5 Hymenoptera : parasitic Formicidae 0 0 0.8 0.8 0.2 0.2 Diptera : Brachycera, adults , larvae Nematocera 0.7 2.2 0.7 0 7.2 3.2 0.2 5.7 0.4 0 1.8 0 Crustacea : Porcellio scaber Orchestia gamma re 11 us 40.9 0 45.6 0 14.1 0 2.0 1.8 Arachnoidea : Araneae Acarina 2.2 33.6 2.4 23.2 10.8 34.8 6.3 37 Myriapeda 10.2 1.6 0 180 compared to the other stations. For more detailed data see Table 8.2.1 and Fig. 8.2.1. The percentual distribution of the different groups of animals (Table 8.2.2, Fig. 8.2.3) shows some similarity between station B and D and between station C and G, respectively. At station B and D, Formicidae (ants) and the species Porcellio scaber (woodlouse) dominated -- at B together with Diptera (flies and gnats) and at D with Collembola (spring- tails), while at station C and G, Araneae (spiders) were strikingly dominant, followed by Diptera. The gammarid Orchestia gammarellus was frequent only at station G where it comprised 10.5% (59 individuals) of the total number of individuals found, while at station C the corres- ponding figure was 0.2% (1 individual). No gammarid could be found at the other stations. At station G there also seemed to be more parasitic hymenopteras and cicadas (Homoptera) than at the other stations. The little wood- louse Porcellio scaber appeared in small numbers at station C and G compared to stations B and D. In one of the traps at station G a shrew (Sorex sp . ) was found in company with some fleas. These latter were not included in the calcu- lations . 8.2.4.2 Quantitative samples The average number of individuals/lOOg wrack dry weight at stations G and C was two to three times higher than at stations B and D (Table 8.2.6) The total number of systematic groups found was 11 at station B and 13 at each of the other stations (Table 8.2.4, Fig. 8.2.2). The percentual distribution of the systematic groups (Table 8.2.5 and Fig. 8.2.4) in this case also showed a similarity between stations B and D and stations C and G, respectively. Porcellio scaber was clearly dominant at station B and D, followed by Acarina (ticks), while Araneae seemed to be less frequent at these stations. Myriapoda (millepedes) made up 10.2% of the total number of individuals found at station B while at C and G this group could not be found either in the quanti- tative samples or in the traps. At station C and G Acarina and 161 mean No of ind/ trap 60- 50- 40- 30 20- 10- } total No of mean No of families ind/ lOOg wrack 250- -40 -30 -20 10 200- 150- 100- 50- 0 total No of families -16 -12 -8 -4 B B D Fig. 3.2.1 Average number of individuals (±standard error of mean) in the pit-fall traps (o) and total number of systematic groups (*) at the four stations . Fig. 8.2.2 Average number of individuals/ lOOg wrack, dry weight (o) (istandard error of mean) and total number of systematic groups (±) in the quantitative samples at the four stations. 182 Table 8.2.6 Total number of individuals (x) occurring in the four quanti- tative samples at the four stations and percent occurrence frequency (%) . Stn B Stn D Stn C Stn G X % X % X % X % INSECTA Collembola fain. Entomobryidae 3 25 9 75 Poduridae 4 50 5 50 Isotomidae 3 25 153 25 Hemiptera 399 75 Homoptera fam. Aphididae 2 25 1 25 2 50 Heteropotera unidentified 1 25 Coleoptera fam. Hydrophilidae 8 100 7 75 Staphylinidae 2 50 2 25 4 50 5 75 Ptiliidae 3 25 1 25 50 75 Nitidulidae 2 50 larvae 1 25 2 25 Hymenoptera fam. Ichneumonidae 1 25 Braconidae 1 25 Proctotrupoidae 1 25 Formicidae, Lasius niger 1 25 2 50 Diptera Brachycera " Agromyzidae 1 25 1 25 larvae 3 50 9 75 29 100 17 100 Nematocera " Chironomidae 3 50 1 25 Cecidomyidae 1 25 1 25 CRUSTACEA Isopoda Porcellio scaber, adults 56 100 57 75 72 100 19 100 ", newly hatched 79 50 44 50 4 25 10 25 Amphipoda Orchestia gammarellus , adults 17 75 , newly hatched 15 25 ARACHNOIDEA Aranae fam. Linyphiidae 3 75 3 25 52 100 59 100 " Lycosidae 3 50 Acarina fam. Ixidae, Ixodes ricinus 46 100 29 75 178 100 346 100 MYRIAP0DA Diplopoda fam. Iulidae 14 75 2 25 OLIGOCHAETA Plesiopora Pachydrilus sp. and Enchytraeus sp. (estimated numbers) 200 75 250 100 2000 100 4000 100 183 Insecta : I Collembola M Hemiptera l!*j Coleoptera S3 Hymenoptera El Diptera Crustacea : K3 Porcellio I ±J Orcliestia Arachnoidea : Araneae(Ar), Acarina D Other Fig. ,2.3 Percentual distribution of the different groups of animals in the pit-fall traps at the four stations. The area of the circles is correlated to average number of individuals per trap. B Fig. 8.2.4 Percentual distribution of the different groups of animals in the quantitative samples at the four stations. The area of the circles is correlated to average number of individual s/lOOg wrack, dry weight. 184 Collembola were the dominant groups. Station G showed a low number of Porcellio scaber, only 2.0% while the gammarid Orchestia gammarellus appeared at this station exclusively. 8.2.5 Discussion The result of the pit-fall trap study shows that the total number of systematic groups was somewhat higher at the reference station and that the average number of individuals caught was 1.5 to 3 times higher than at the other stations. The quantitative samples however, show that the total number of systematic groups was similar for all stations except station B, which had a slightly lower figure. The average number of individuals per 100 g wrack was clearly higher at station G compared to stations B and D, hut a little lower than at station C. This could be due to the wrack at G being too wet for some animals, which would explain the low number of Porcellio at this station (Backlund, 1945). The fact that the gammarid Orchestia was frequent only at G and absent at the contaminated stations might be a result of the oil spill, but it could also be a consequence of the humidity of the wrack at G (Backlund, 1945). This does not explain the almost complete absence of this species at C, where the wrack was as wet as at G. The differences in humidity of the wrack are clearly shown by the abundance of the group Plesiopora (Oligochaeta) which demands humidity for thriving (.Backlund 1945). This 2 2 group is much more frequent at G and C (about 27,000/m and 13,000/m 2 2 resp., estimated values) than at B and D (about i , 100/m and 1,300/m resp.). The largest part of this group was Pachydrilus sp . and the rest Enchytraeus sp. Pachydrilus is a typical animal of the seashore and abundant in wrack beds, being the main food source for many animals living there, e.g., spiders of the genus Erigone sp. and larvae of the coleopteran Cercyon sp . (Backlund, 1945). Most of the flies (Brachycera) in the quantitative samples were larvae because the adults are able to fly and thus escaped capture. The great number of flies in the traps could be due to their being attracted by the smell of the detergent, as most of them are not true inhabitants of the seashore (Chinery, 1976). Species which truly belong to this 185 biotope, for instance Lispe tentaculata (family Muscidae) , Dexiopsis lacteipennis (family Muscidae, according to Hugo Andersson, Lund, pers. comm. , not known in this county before), Scatophaga litorea (family Scatophagidae) , and Ephydra macellaria alandica (family Ephydridae) contribute only 10% of the total number of flies while Dolichopodidae and Agromyzidae made up the major parts (49% and 26%, resp.). Some of the flies are parasites on other insects, e.g., individuals of Phoridae (Chinery, 1976) and Tachinidae (Lindroth, 1967). One individual of the family Pipunculidae was found at Station G. Members of this group are known as parasites of cicadas (Homoptera) (Lindroth, 1967) and were found only at this station. Some of the parasitic hymenopteras are fly parasites, e.g., Tricopria sp. and Trimorus sp . These were also found at Station G where the greatest number of flies occurred. The only hymenoptera species which truly belongs to the shore is Urolepis maritima which appeared at Station G. Most of the Ichneumonidae would seem to have come from the woods (Cederholm, pers. comm.). Perhaps these were also attracted by the detergent. According to Backlund (1945) nearly every wrack bed contains parasitic hymenopteras living on dipterous larvae. The high number of ants (Formicidae) at Stations B and D could be explained by ant hills in the wood beyond the shores. A greater part of the spiders consisted of the species Oedothorax retusus, (family Linyphiidae) , small web-spinning spiders which are found especially in littoral vegetation and on the surface layer of wrack (Backlund, 1945). The genus Erigone (family Linyphiidae) was also found. One third of all the spiders was made up of Lycosidae, hunting spiders which probably live to a greater extent on flies (Backlund, 1945). The genus Arctosa , Trochosa and Pardosa were also found. All of the ticks found belonged to the species Ixodes ricinus , which live in decaying organic material and lay their eggs in the ground vegetation (Ursing, 1971). At Station G there was more vegetation around the wrack bed, which could have influenced the number of aphides (Aphididae) which occurred here in larger numbers than at any other station. One species (Hyalopterus pruni) has for instance Phragmites as i summer host (Lindroth, 1967). It is possible that the individuals found belonged to this species, but no further examination was made. 186 The dominant group of Coleoptera (beetles) were carabides of the species Pterostichus niger followed by Hydrophilidae of the genus Cercyon, common in decaying wrack on shores (Chinery, 1976). These occurred only at Stations C and G, where the humidity was high, since they feed on even wetter wrack than Orchestia (Backlund, 1945). The family Ptilidae was also frequently found, some species of which are very common in wrack beds (Backlund, 1945). Staphylinides , of which many species live on shores and feed on Diptera larvae, also occurred in the samples as well as Nitidulidae, which lives on decaying material (Chinery, 1976). In all calculations the newly hatched individuals of Porcellio and Orchestia were omitted. At station B there were 81 newly hatched Porcellio (among 19 adults) still clinging to the mother adult in one trap, and in one quantitative sample there were 75 newly hatched individuals of the same species among 6 adults at the same station. If these had been taken into account, the average number of individuals in each trap would have increased to 27 (instead of 20), just a little less than at the other stations and the average number of individuals per 100 g wrai k would then become not 85 but 158. This would make the figure comparable to that at station G. In fact, fur the small amount of material examined the differences in number of individuals and systematic groups between the stations are not so large that they could not be explained by the natural variation caused by the environment. The wrack bed is a rela- tively variable environment, strongly affected by storms. Nevertheless it was of a similar nature throughout the whole area investigated during the sampling period, so that a comparison could be made between the s t iti'-ns. The humidity is a factor of great importance to the animals living in the wrack itself (Backlund, 1945). Water makes the wrack much softer and mure accessible and therefore easier to eat. Orchestia for example cannot eat hard and dry wrack (Backlund, 1945). Another important factor influencing the wrack fauna are the interactions over the "bound- aries" to adjacent biotopes (Backlund, 1945). At station G for example tin bed of reed comprises another biotope containing other types of animals supplying immigrants to thi rick fauna. Thus the surrounding biotopes influence wrack beds both quantitatively and qualitatively. 187 The low number of individuals at station B could be a result of the oil spill but it is more likely a result of the ground being turned over during the clean-up procedure, a measure which destroyed the wrack more or less completely. Since there were no storms during this period, when Fucus might have blown ashore, the remaining wrack bed became rather diminished, and this in turn influenced the animal life. 8.2.6 Conclusions Unfortunately no similar investigation had been made in this area either before or directly after the accident, which makes it difficult to draw firm conclusions. The present investigation indicates, however, that the oil spill from Tsesis has not had any great and long lasting negative effects on the fauna of the wrack belts of the shore. It seemed to recover rather quickly, due both to the short generation time and the vagility of the animals. Another important factor was the time of the accident . It took place in the late autumn when many animals had already left the upper, most affected part of the ground in preparation for hibernation. Had it happened in the early spring it is possible that the results would have been different and shown longer lasting effect . 8.2.7 Acknowledgements The following persons deserve thanks for great help with exam- ination of the animals: Dr. Carl-Cedric Coulianos (Brachycera and Coleoptera), Dr. Torbjorn Kronestedt (Araneae), Dr. Lennart Cederholm (Hymenoptera) and Dr. Hugo Andersson (Brachycera). 8.2.8 References Backlund, H.O. 1945. Wrack fauna of Sweden and Finland, Ecology and Chorology, Lund. Acad, diss., Opuscula entomologica Suppl. 5: 1-236. Chinery, M. 1976. Nordeuropas lnsekter, En Bestamningsbok. Handledning for bestamning av samtliga insektfamiljer i nordeuropa. Albert Bonniers fb'rlag AB , Stockholm. 1-371. (In Swedish). 188 Lindroth, CM. 1967. Entomologi, Biologi 7, AJmqvist and Wiksell, Stockholm. 1-236. (In Swedish). Lindroth, C.H. 1942. V9ra skalbaggar och hur man kanner igen dem, Del I-III, Albert Bonniers Fb'rlag AB, Stockholm. 1-222. (In Swedish) . Ursing, B. 1971. Ryggradslbsa djur, P. A. Norstedt och Sbner Fbrlag, Stockholm. 1-369 . (In Swedish). 189 9. Impact of Oil on Local Fish Fauna CHAPTER 9: IMPACT OF OIL ON LOCAL FISH FAUNA (Sture Nellbring, Sture Hansson, Gunnar Aneer and Lars Westin) 9.1 Introduction From earlier echo sounding surveys (Aneer et al., 1978) it is known that pelagic fish (herring, Clupea harengus membras , L. and sprat, Sprattus sprattus L.) are very abundant in the spill area during late autumn and winter. It is also known that herring spawn in the archi- pelago in the spring. In view of the not inconsiderable local com- mercial fishery, the following questions were of interest after the spill: Were the pelagic fish still present in the area and were the fish contaminated by the oil? Did the oil affect the spawning grounds and the hatching results (c.f. Linden, 1976)? 9.2 Material and methods To investigate the occurrence of pelagic fish in the polluted area, echo sounding surveys were carried out on four occasions (11 November 1977, 15 December 1977, 11 January 1978, and 12 April 1978). The survey routes are illustrated in Fig. 9.1. Herring were caught with gill-nets or by trawling. Organs (gills, stomachs) and whole fish from the reference and affected areas were deep-frozen for oil analysis. In order to investigate spawning grounds, 100 randomly chosen non-polluted stations and 20 polluted stations were visited in June 1978 (about seven months after the spill) by SCUBA divers to see if any spawning had taken place. At each station, the divers investigated the bottom from the shoreline down to a depth of about 10 m. At stations in the affected area where spawning had taken place and at four non-polluted reference stations, egg samples were taken for hatching in the laboratory. At each station two samples were taken by cutting and removing sections of algae with attached roe. In the labor- atory the two samples were mixed and ten sub-samples of about 50-100 193 TORO i — 2 km Fig. 9.1 Echosounding survey routes Qy = Tsesis -- ' = Survey routes (scale 1:50,000) 194 eggs each were placed in hatching chambers with a volume of about 100 ml (Fig. 9.2). These were kept in the hatching chamber system for 7-12 days. Two or three days after the appearance of hatched larvae in a chamber, the contents were removed and preserved in 4% formaldehyde for later examination. The temperature in the chamber system was between 10 and 14 C, corresponding to the in situ temperature for that time of year. The oxygen content of the water in the hatching chambers was almost saturated. 9.3 Results The echo sounding surveys did not indicate any decrease or disappear- ance of pelagic fish within the oil spill area. Furthermore, chemical analysis of herring organs and whole fish showed no indication of oil contamination (Boehm, pers. comm.). The frequency of spawning grounds was lower in the contaminated area than in the reference area (20%, n =20 and 45%, n =100). (Fig. 9.3 2 2 and 9.4). A x test was carried out (x = 3.3, d.f. = 1) and the result was found to be significant at the 7% level. There was no significant difference in the number of malformed larvae. Only two larvae with enlarged areas anterior to the yolk sac were found in two samples from the polluted area (picture, Linden, 1976). The hatching results are presented in Table 9.1. These are divided into two columns, representing two different counting methods. The first column (observed hatching) gives the percentage of hatched larvae. The second column (theoretical hatching) gives the percentage of hatched larvae plus the percentage of eggs with live nearly hatched larvae. The hatching of eggs from one reference station, Jutskar, was unsuccessful. This was probably due to a severe fungal infection, the causes of which are unknown. As can be seen in Table 9.1, the average hatching success was lower in the oil polluted areas. The hatching success of eggs from Tistelholmen, the most affected area, was extremely poor, about 20% (theoretical hatching). 195 W (X W Eh < I < En < M g w © * V^WAWW v\\\v>r ^yv^o,\\\^ t^ en ■H O aj c ■rl x) •h C CNl 00 •H 196 V * *« y & cr P > P 0.006, observed hatching, z = -2.96, 0.0032 > P > 0.0026). It is worth noting, however, that one of the polluted stations, Tistelholmen, gave highly variable results, with significant differences between the three sampling occasions (rank-sum test for several samples (Dixon and Massey 1969:345), H observed = 97.9, d.f. = 2, H theoretical 94.6, d.f. = 2, p << 0.01 in both cases). 9.4 Discussion The analysis of herring did not indicate any contamination by oil (Boehm, pers. comro.). However it would be of great interest to trace the path of the oil through the food chain by carrying out oil analyses on flounder (Pleuronectus flesus) . These fish feed mainly upon Macoma balthica and the blue mussel (Mytilus edulis) both of which have been shown to contain considerable amounts of oil. The low frequency of spawning by herring in the affected area may indicate effects of oil pollution. It may, however, also be due to the differences that undoubtedly exist between the polluted and reference areas as regards exposure and sediment type distribution on the fairly shallow bottoms, where herring spawn was found. On comparison, it is clear that the hatching of herring eggs was less successful in samples from the oil affected area. Significant differences also between samples from within the polluted area may, however, indicate that factors other than oil pollution may have in- fluenced hatching rate. One such factor, repeatedly observed in the hatching experiments, was fungal infection of the roe. From previous studies it is known that the presence of benthic crustaceans decreases the amount of fungal growth on fish roe (Oseid, 1977). In the spring after the oil spill, hardly any adult Gammarids were present in the polluted area. It is therefore possible that their absence led to increased fungal attack on fish roe. 200 9.5 References Aneer, G. , A. Lindquist and L. Westin. 1978. Winter concentrations of Baltic herring (Clupea harengus var . membras L.) Contrib. Asko Lab., Univ. Stockholm. No. 21. 1-16. Dixon and Massey. 1969. Introduction to statistical analysis. McGraw- Hill. Kogakusha, Tokyo. 1-638. Linden, 0. 1976. The influence of crude oil and mixtures of crude oil/ dispersants on the ontogenic development of the Baltic herring Clupea harengus membras. Ambio 5: 136-140. Oseid, D.M. 1977. Control of fungus growth on fish eggs by Asellus militaris and Gammarus pseudolimnaeus . Trans. Am. Fish. Soc. 106: 192-195. 201 10. Laboratory Studies Carried Out in Connection with the Spill CHAPTER 10: LABORATORY STUDIES CARRIED OUT IN CONNECTION WITH THE SPILL 10 . 1 Introduction In connection with the Tsesis oil spill some laboratory studies were carried out on animals brought to the Asko laboratory from the affected area. The reason for these investigations was to provide information on possible sublethal effects of the oil on organisms in the area . Three types of investigations were carried out: 10.2 Respiratory measurements on the mussel Mytilus edul is . 10.3 Measurements of byssus formation by Mytilus edulis . 10.4 Burrowing behavior in the clam Ma coma balthica . 10.2 Respiration measurements on the mussel Mytilus edulis (Sture Hansson) The rate of energy turnover in organisms is known to be affected by pollutants. One indication of oil-induced effects on the energy turnover would be changes in the respiration rate. However, measurements of the respiration rate alone cannot be used to determine how energy turnover is affected as a number of other components in the budget might also be affected, e.g., growth rate or food ingestion. 10.2.1 Materials and methods Mussels were collected by SCUBA diving from the upper 3 m at oil polluted littoral stations and from the same depth range at an unpolluted reference station by means of a dredge from the shore. The mussels and 2 liters of the surrounding water were collected in ethylene containers which were sealed underwater to avoid contamination by the surface oil slicks . In the laboratory the mussels were allowed to acclimatize for 2-4 hours before the start of the experiment. The temperature during the experiments did not differ by more than two degrees from that in situ, and field temperature and salinity varied negligibly between stations. 205 Animals from unpolluted localities were incubated in clean water, while those from polluted localities were incubated in water collected together with the mussels. The measurements were made on specimens with a mean shellfree dry-weight of 31 mg (S.D. = 8 mg, shell length = 17-22 mm). Single specimens were incubated for 50 to 150 minutes in syringes with a volume of 10 ml and a diameter of about 15 mm. In order to study the acute effects of high oil concentrations, fresh mussels were incubated in a laboratory prepared oil-in-water mixture. This mixture was prepared from 10 ml of Tsesis oil and 900 ml sea water which was mixed using a magnetic stirrer for 18 hours at 20 C. The water phase served as an incubation medium and was used both undi- luted and diluted (1:10) and was added fresh at the start of the incu- bation. Mussels incubated in uncontaminated Baltic sea water were used as a reference. The oxygen concentration was measured in control syringes with both polluted and unpolluted water which had been incubated as long as the syringes with animals present. These values were then subtracted from measurements with animals present, before the oxygen consumption of the mussels was calculated. Concentrations were determined with a Radiometer oxygen electrode (D 616) connected to a Radiometer PHM 716 with a P0 -module, PHA 930. 10.2.2 Results Data from the respiration measurements are presented in Tables 10.2.1 and 10.2.2 and illustrated in Fig. 10.2.1. The respiration rates of M. edulis from different localities, and those from the experiments with different incubation water, were examined with Bartlett's test (Bailey 1976:189) and with analysis of variance (Dixon and Massey, 1969 : 156-162)* in order to determine whether variances or means were significantly different. When variances in the measure- ments from all stations (polluted and unpolluted) were compared no differences were found (x = 8.17, df = 6). However, in testing the means by analysis of variance, a p-value between 0.005 and 0.001 (F., = 4.098) was obtained rejecting the hypothesis that all the samples came from populations with the same respiration rates. 206 CM O 03 H 03 M - ^^ S CM O oo 4-1 03 o >> 01 c = S-i 4-1 01 01 01 c o 03 o u E 0 4-1 Sh c 01 S- •H — i 03 0) 0) 3 00 > 4-1 ••-I c V4 E Ol 03 M ■H o C v — ' — 4-1 O 01 -D T3 T3 ■H 4-> 03 a 01 d 4-1 js ~a 03 4-1 01 03 oo o> 03 4-1 ■H 4-1 WJ u 01 03 01 3 •H 4-1 -G 3 — 03 03 4-J 0) d — 03 3 o >» 03 O — i— 1 4-1 d S-i 0) ft 1 4-> . — I ■H 03 01 Sj Q s r— I X C 01 •H M 01 o 14-1 o ■H S-l 'l-l 01 oj 03 4-1 Sh d £ 3 03 o 1 03 S-i 01 Sh >^ 4-> 4-1 x: 4-1 S-i i—4 c H T3 a 01 Ph 03 03 u E u •H aj 01 d • OJ 0 i— < 01 S-l o i— 1 H a S-l o ■ ~ <4-4 0) CM oj 1 — c • 1— 1 H 01 r~ • I— 1 X 01 s 01 >> • 4-> JA X oo 03 <4-l w 01 o •H o o 03 1—1 03 c P*4 03 > 03 01 0) c Sh 0) 0) 4-1 o 01 E 01 03 4-1 S-l T3 a II ~ 0) •H 01 — d 01 CM c Ol o 01 01 o o 4-1 •r-l 11 CJ •H d 4-1 S-l d 3-9 4-) r— 1 03 — OJ 03 .— 1 S-i X -r 4-1 o •H 0) •i-H 01 — Ph M-l ■^ 01 01 G 01 01 1 — 1 CO S-l o 03 x; •H OS 03 CJ 3 4-1 3 d o 4-1 03 oj h t\i cn h m n 00 Ol r-4 CM IT) CO CM \c so — i cm c^ r- oo oo oo so i— i o N 1/1 vO 1/1 N N N oi oi oi r^ o> 0> 0"\ 01 Ol 3 3 3 o o o o o o 3 Cm Dj Qj Oh Ch Oh H r—t r^i r^i ^^ ?*% r^> ?^ O r— I r—{ rH ^H ^H rH Oh -r-l -H -H 4-1 -H 'H > > > XI > > 4-1 03 03 03 00 03 03 O 0) 0) 0) -H 0) 01 2SXI JXS d 4-1 CO 01 w o Pm o u ea o c c d d c CI d 0) o o o 0 o o Sh •H ■H • 1-1 •l-t •H •H 01 4-1 4-> 4-1 4J 4-1 4J 4H 03 03 03 03 CO 03 01 4-1 4-1 4-1 4-1 4-1 *J OS CO 00 CO CO 00 CO Sh 01 03 01 O Oh I ■—I •H O 03 •H CJ Sh 03 d 03 d 03 0) T3 01 4-> 03 — 3 CJ 3 /—\ •H — i 01 CM •H rH O 3 — -r 0) 0) r— 1 XI ~ 03 H 4h O 0> 0) 01 01 Ol 4-1 •• 03 03 S-l d o d •H o 4J •H 03 4-1 ■H 03 > Sh Ol ■H Sh a. — 01 — 0) < OS eg CM o XI d 03 X 01 ~ X N O . 4J oc c D- • H 01 i) CJ 4J d 03 Co Sh T3 •H d 4-| o d •H o 4-1 CJ 03 Sh s« ■H Ch U0 01 ~ 01 ■^ CM O at E • •— ^ > 0) 4-> ■a X! • X 01 ■H Ol 3 d >. 03 Sh OJ a ^. Ch E CJ 0) o H 03 Q 03 E-i Sh 01 4J 03 d o •H 4-1 03 x> 3 CJ C o i — i r~~ r~~ sO uO CO m CM 00 o oo U0 t/1 O i — so oo CO 00 CO 00 so 00 so r~- CM CM CO CM r— r~- 10 Sh 01 01 4J ^h 3 03 i— 1 3 -i Sh O 01 -O Ph -j o •• 03 4-) a 3 3 03 i—l 0) /— -* T3 Sh i—l r-4 ■—I 01 0l O U 4J 4-1 Oh c^ 3 03 0) i—l 3 >> Sh II ■ — i i-H 3 o 3 4-1 4-> Sh Ph 03 X! X 01 0) OO -H 4J i—l i—l ■h e CO •H CJ i-j -^ 3 c 207 500- - 100 Respiration ( jug 09/g-h ) Temp. = 9 UC o J- CD +-> in CD <_> c CD s_ CD <+- CD Qi B Temp. 8 UC -a CD +-> (T3 13 O C T3 CD S- CD +-> fO 3 c CD +-> r- E • • O CTi O ■l- s- O CD +-> • • fO 3 3 "O CD C +-> fO rt3 CD C <_> (_> E CD CD (0 e (0 +J E o C_) Fig. 10.2.1 Respiration rates (means with 95% confidence intervals) of Mytilus edulis from clean and oil-polluted localities(A) and of animals incubated in clean and artificially oil-contaminated water (B) 20* From Fitf. 10.2.1 it can be seen that animals from three of the stations (D, E, F) showed lower respiration rates than animals t rum other stations. This result can, however, be explained by the fact that M. edulis from stations D, E and F were incubated in water with lower oxygen contents than those from the reference station (Table 10.2.1). It is known that low oxygen concentrations depress the respiration of Myt i lus edul is (Bayne, Thompson and Widdows, 1976). If the remaining stations (B, C, G) and the reference station (.all had about the same oxygen content in the incubation water. Table 10.2.1 ) were compared no differences could be found between variances (\ = 1.93, df = 3) or between means (F .. = 0.85). (3: j9) The results from the experiment with Myt i lus incubated in water with different oil-concentrations (Table 10.2.2) also failed to show 2 statistically significant differences between variances (x = 1.44, df = 2) or means (F, , = 1.26). 10.2.3 Conclusions and discussion According to this study, oil contamination of the water did not significantly change the respiration of Myti lus edul is . However, due to the large variability in respiration, (mean values of approximately 650 |.ig 0 /g/h and standard deviations about 150 pg 0,-,/g/h ) , changes would have had to be large, in order to be detected. To detect, with a probability of 90%, a difference in respiration rate of about 20%, the sample size ought to be some 30 specimens (Dixon and Massey 1969, Table A-12a). 10.2.4 References Bailey, N.T.J. 1976. Statistical Methods in Biology. 10th ed. Hodder and Stoughton, London. 1-198. Bayne, B.L., R.J. Thompson and J. Widdows. 1976. Physiology I. In: Bayne, B.L. (ed.). Marine mussels. Their ecology and physiology. Cambridge University Press. Cambridge. 121-206. Dixon, W.J. and F.J. Massey. 1969. Introduction to Statistical Analysis. 3rd ed . , McGraw-Hill, Kogakusha, Tokyo, 1-638. 209 10.3 Measurements of byssus formation by the mussel Mytilus edulis (Olle Linden and Maria Foberg) Methods : Oil-affected mussels were collected in the littoral zone off Toro about one week after the grounding of the Tsesis . At this time large quantities of oil were floating on the surface. The mussels were collected by a diver at 4-5 m depth and brought to the laboratory in plastic bags. Care was taken to avoid contamination by the surface oil film. Reference mussels were collected close to the Asko laboratory in a similar but unpolluted biotope. In the laboratory the mussels were allowed to acclimatize for a couple of hours. After this period mussels of two length-classes (ju- veniles: up to 10 mm, adults: over 10 mm) were placed on petri-dishes which were immersed in unpolluted sea water. Twenty to 25 animals of each length-class from each locality were exposed to a continuous flow of sea water in ~10 litre plastic jars. The number of mussels byssally attached to the dish after 3, 4, 5 and 6 hours was noted. Results and discussion: Fig. 10.3.1 shows the percentage of mussels byssally attached during the course of the experiment. Indi- viduals from the impacted area showed decreased tendency to attach to the substrate. This tendency is more pronounced among adult individuals compared to juveniles. Reduction or absence of byssus thread production in mussels (Mytilus edulis) or related species under the influence of oil, has previously been observed under laboratory conditions (Smith 1968, Swedmark et al . 1973, Eisler 1973, Linden 1977). It is obvious that affected byssal activity under natural conditions must be considered a serious stress syndrome. Mussels incapable of byssal thread production will be unable to remain in their natural habitat as threads are used as mooring lines. They will consequently be washed away and their chances of reattachment at a suitable place are probably rather small. The experiments, although performed under laboratory conditions, indicate that the mussels in the impacted area were subjected to such effects. 210 Q UJ O CD ta cu 1-1 x: CO 3 CO CO >•■ E s-j o o a CU TJ C CU CO 4-1 4-1 i-H ^-x 3 CO T3 •H Cd i— 1 3 II ~ U T3 CO CO 3 "O ^H c •H CO l-l >. CO s CU *-s .-1 •H H C CU CU 'X > w 3 3 ■I- 1 £ II cu 3 > H 3 P3 CO O •H sav3dHi snssAa sNiwaod sivwinv 211 References Eisler, R. 1973. Latent effects of Iranian crude oil and a chemical oil dispersant on red sea molluscs. Israel Journ. Zool. 22: 97-105. Linden, 0. 1977. Sublethal effects of oil on molluscs species from the Baltic Sea. Wat. Air Soil Pollut. 8: 550-558. Smith, E. (ed.) 1968. Torrey Canyon, pollution and marine life. Cambridge Univ. Press. 1-196. Swedmark, M. , A. Grannio, and S. Kollberg. 1973. Effects of oil dis- persants and oil emulsions on marine animals. Water Res., 7(11): 1649-1672. 212 10.4 Burrowing behavior in the clam Macoma balthica (Olle Linden) Methods : Oil-affected clams were collected at 15-20 m depth off Toro about one week after the grounding of the ship. At this time large quantities of oil were floating on the surface. The clams were collected by a diver and brought to the laboratory in closed plastic jars. Refer- ence animals were collected off the Askci laboratory in an unpolluted area of similiar depth. After acclimatization in the laboratory for 2-3 hours, about 20 clams of each of three length-classes (3-4 mm, 4-9 mm, 10-15 mm) from each locality were spread out over the surface of a 5 cm thick, uncon- taminated sediment layer in several glass jars. The glass jars were immersed in basins containing unpolluted sea water. The number of clams that had buried themselves completely was counted at several time intervals . Results and discussions. The rates of burrowing of the bivalve are shown in Figure 10.4.1. On the whole the control animals showed the highest burrowing rate, and all individuals had buried completely within 60 min. The animals from the polluted area showed a clearly decreased burrowing rate. Affected burrowing behavior among clams under the influence of oil pollution has previously been reported by Shaw et al. (1976), Linden (1977) and Taylor and Karinen (1977). As this experiment was performed under laboratory conditions, the ecological consequences of the observed effects are still unproven. However, under natural conditions behavioral disturbances such as im- paired burrowing will most probably, in the long run, be unfavorable for this organism. Clams unable to burrow normally may have their food finding affected as they are deposit feeders. Furthermore, the impor- tance of burrowing behavior in the predator-prey relationship is obvious. The results reported here have demonstrated that the clam Macoma balthica during the Tsesis oil spill may have been subjected to such sublethal effects. 213 ex o > < X UJ CQ ID O tx ZD CQ ID % 100 ANIMALS FROM A CONTROL AREA 50- 0 % o " 100 CO • - 3-4 MM o = 8 " . = 10-15 " ANIMALS FROM A CONTAMINATED LOCALITY 60 105 mN Fig. 10.4.1 Macoma balthica burrowing behaviour 214 References Linden, 0. 1977. Sublethal effects of oil on molluscs species from the Baltic Sea. Wat. Air Soil Pollut. 8:550-558. Shaw, D.G., A.J. Paul, L.M. Cheek and H.N. Feder. 1976. Ma coma balthica: an indicator of oil pollution. Mar. Pollut. Bull. 7: 29-31. Taylor, T.L. and Karinen, J.F. 1977. Response of the clam Ma coma balthica exposed to Prudhoe Bay crude oil as unmixed oil, water- soluble fraction, and oil-contaminated sediment in the laboratory. In: Wolfe, D.A. (ed.): Fate and effects of petroleum hydrocarbons in marine organisms and ecosystems. Pergamon Press, Oxford. 229-237. 215 11. The Analytical Chemistry of Mytilus edulis, Mgcomg balthica Sediment Trap ana Surface Sediment Samples CHAPTER 11: THE ANALYTICAL CHEMISTRY OF MYTILUS EPULIS, MACOMA BALTHICA SEDIMENT TRAP AND SURFACE SEDIMENT SAMPLES- (Paul D. Boehm, Judith Barak, David Fiest and Adria Elskus) 11.1 Introduction It has become increasingly apparent in recent years that the tem- poral impacts of spilled oil in the marine environment become more prolonged when the fate of petroleum hydrocarbons includes transport into the sediment. Recent studies by Teal et al. (1978), Keizer et al. (1978), and Mayo et al. (1978) indicate that aromatic and aliphatic hydrocarbons from spilled petroleum persist in the sedimentary environ- ment for substantial periods of time (years). While degradative pro- cesses, both chemical and microbial, act to alter the composition of the oil in sediment, the toxicants and carcinogens may persist in the sed- iment depending on factors such as sediment grain size, wave energy (Owens, 1978), and oxidation state of the sediment (Anderson et al., 1978). There have been few field studies directly pertaining to the sedimentation of oil owing to natural processes. At least three pro- cesses can lead to the transport of petroleum from a positively buoyant state in the water column to negatively buoyant state reaching the sediment. First, some oils by virtue of an initial density close to that of water (e.g., Bunker C) can weather at sea, lose volatile or soluble components, and sink (Conomos, 1975). Such behavior was apparently observed after a Bunker C spill in cold water off the coast of Greenland (Mattson and Grose, 1978). Secondly, oil can adsorb to living particulate matter or detrital particles and sink due to sedi- mentation. This process is dependent on the availability of sediment particles as well as the nature of the particulate matter (National Academy of Sciences, 1975; Meyers and Quinn, 1973; Poirier and Thiel, 1941). Another route of transport to the benthos is by ingestion of oil by zooplankters followed by fecal pellet transport (Conover, 1971). A further indirect process is deposition after landfall by seaward trans- port of beach and intertidal sediment with associated petroleum. " Work carried out by Energy Resources Co., Inc. under Contract No. MO-A01-78-4178 to OCSEAP. 219 Shaw et al. (1976) have suggested that Ma coma balthica represents an ideal organism to monitor exposure of the benthos to pollutant input due to its deposit feeding behavior, while others have suggested that filter feeders (e.g., mussels, Mytilus species) are good indicators of oil in the aqueous environment due to their manner of processing large volumes of water. Due to their widespread distribution in coastal waters, mussels (Mytilus sp.) have been closely studied in laboratory and field experi- ments for their responses to hydrocarbon pollutant exposures. Studies on the hydrocarbon chemical content of species of mussels have been performed relating to (1) background or chronic input levels in Mytilus galloprovincialis (Fossato and Siviero, 1974), M. edulis (Ehrhardt and Heinemann, 1975; Rudling, 1976), M. californianus and M. edulis (DiSalvo et al., 1975); (2) laboratory hydrocarbon uptake and depuration studies (Lee et al., 1972; Fossato and Canzonier, 1976; Kanter, 1974; Clark and Finley, 1975); (3) field transplantation (uptake and depuration) studies (DiSalvo et al., 1975; Fossato, 1975; (4) oil spills in the field (Grahl- Nielsen et al. , 1978; Clark et al., 1978, among others). Mytilus sp . is a suspension feeder which processes large volumes of water to obtain food and in doing so is exposed to hydrocarbon and other pollutant compounds dispersed in the water or adsorbed to particulates. Mytilus itself is a food source for many animals, but in the Baltic it is not utilized by man. Furthermore its sedentary nature within the littoral community makes Mytilus populations both excellent markers of pollutant exposure within this zone as well as indicators of temporal recovery of the littoral zone. This chapter concentrates on the extent of Tsesis oil exposure of the Mytilus edulis population and the long-term (1 year) tissue hydro- carbon burden of populations around the region affected by the Tsesis oil spills. For details on the spill, see section 1.2. Of particular interest were the changes in both the quantitative and qualitative nature of the aliphatic and aromatic hydrocarbon assemblages in the tissues. Ma coma balthica , a prominent resident of the soft-bottom community, was used as an indicator of pollutant input to the benthos. 220 A year-long study of these animals together with supportive measurements from surface sediment and sediment trap samples will be the means to determine the chemical fate of oil from this spill and propose a des- criptive model for the behavior of the oil after the spill. 11.2 Methods 11.2.1 Sampling Sampling was carried out by the Swedish scientists from the Asko Laboratory, University of Stockholm, and the Swedish Water and Air Pollution Research Institute (IVL) as part of their ecological impact study. Sampling of Mytilus were obtained periodically from eight of the stations in the study area indicated in Figure 11.1 (B, C, D, E, F, G, I, J). Baseline chemical information was obtained by sampling at stations C, D, and G prior to the oil's landfall. A reference station J adjacent to the biological laboratory on Asko Island was sampled in October of 1978 after it became apparent that the original reference site G was indeed impacted by the oil. Macoma samples were obtained in grab or dredge samples taken at nine soft-bottom stations shown in Fig. 11.1 (C, D, 2, 5, 6, 7, 8, 15, 20). Station 15 was chosen as the reference station not believed to be impacted by the Tsesis spill. At each station at least 5 grams wet weight of Mytilus and Macoma tissue were obtained. Individual specimens measured from 1 to 3 cm and each sample for analysis consisted of 10 to 60 individuals. Samples were frozen after collection and transported using dry ice for preser- vation. Sediment traps (see section 4.2.3.5 for details) were deployed at three stations in the area (II, IV, V). Sediment samples were collected as described in section 6.2.1. The collected material was stored frozen prior to analysis. 11.2.2 Sample Analysis Once in the laboratory the shells of the frozen samples were rinsed with distilled solvent. The specimens were then shucked, tissues com- bined and weighed and added to 50 ml Teflon capped centrifuge tubes. 221 Figure 11.1 Map o f St ud y k re a and Station Lo c a t io n s KEY Roman numerals (T , II, III, IV, V, VI) = pelagic sampling stations Arabic numerals (2, 5, 8, 15, 20, 21 ) = benthic sampling stations Capital letters (B - J, exc . H) = littoral sampling stations or benthic stations in the proximity of a littoral station. 222 58049.7'N — t^g^strMS 17043.8'E 223 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. Internal standards were added prior to digestion and carried through the entire procedure (f, = androstane; f„ = hexaethyl benzene). Standards were also added to sediment and sediment trap samples (see below). The digestate was extracted three times with distilled hexane in the centrifuge tube. The extracts were combined, concentrated to 0.5 ml, weighed on a Cahn electro- balance, and fractionated on an alumina over silica gel column (Boehm, 1978). Two fractions corresponding to the aliphatic or f, (hexane eluate) and the aromatic/olef inic or f0 (methylene chloride eluate) hydrocarbons were obtained for gas chromatographic analysis. Sediment samples were extracted using the method of Boehm and Quinn (1978) and fractionated as stated above. Sediment trap samples (~1 gram) were extracted in closed centrifuge tubes with a methanol-hexane solvent mix in a boiling water bath for 4 hours. The solvent was obtained, concentrated, and fractionated as stated. Chromatographic fractions were concentrated to 50 pi and a 1 pi subsample was injected into a Hewlett Packard Model 5840A gas chromato- graph equipped with a flame ionization detector. Samples were chromato- graphed in the splitless injection mode on a 15-m (0.25-mm i.d.) SE-30 glass capillary column (J and W Scientific; "^50,000 theoretical plates). The column oven was temperature programmed from 60 C to 275 C at 3 C per minute. The injection port and detector temperatures were 250 C and 300 C, respectively. Peak areas were obtained using a digital integration option which resets the baseline at every valley. Thus peak areas above the unresolved complex mixture (UCM) or hump were digitized. Peak area and retention time information for the sample peaks and the internal standard was transmitted using an HP 18861 digital interface to a PDP 10 computer which computed retention index and quantitative data according to programs developed at ERCO. 224 The unresolved complex mixture (UCM) was quantified using planimetry according to published procedures of Boehm and Quinn (1978) and Farrington and Quinn (1973), and relating its area to that of the internal standard through an integration unit to planimeter unit conversion factor. Combined glass capillary gas chromatography/mass spectrometry was performed on a Hewlett-Packard 5985 GC/MS/computer system for peak identifications and quantifications, using selected ion monitoring. GC/MS was used primarily as a tool for investigating aromatic (f~) hydrocarbon fraction contents of a selected set of tissue and sediment trap samples. Quantitative GC/MS was performed on selected aromatic hydrocarbon samples, GC/MS response factors were computed by examining the instru- mental response of a given amount of aromatic standard relative to that for the internal standard (hexaethyl benzene). Response factors for components for which no authentic standards were available (e.g. C^ phenanthrene, C and C fluorenes, C and C dibenzothiophenes) were computed by extrapolation from the factors for parent and monomethylated compounds. Total ion currents for parent (M ) peaks were obtained for each component of interest, relative response factors applied, and converted to concentration units by comparison to the internal standard amount . 11.3 Results 11.3.1 Mytilus edulis All of the stations in the littoral zone were sampled from the time of the spill event through early May 1978. In addition, two of the stations C and D, along the eastern shoreline, and one near the spill off Fifong Island (G) were sampled prior to landfall of the oil (base- line samples) and through October of 1978. Results of these analyses are presented in Tables 11.1 through 11.4. 11.3.1.1 Aliphatic Hydrocarbons The data in Table 11.1 document a very rapid uptake of Tsesis oil by the littoral bivalve Mytilus. Aliphatic hydrocarbon concentrations 225 TABLE 11.1 ALIPHATIC HYDROCARBON DATA ON MYTILUS EDULIS SAMPLES Fj ALIPHATICS ( yq/q ) DRY PRIS/ ALK/ ISO SAMPLE DATE WEIGHT RESOLVED UCM TOTAL PRIS PHY PHY (13-18 (C) 10-27-77 1.54 1.9 71.0 72.9 nd 0.08 - - 11-14-77 0.64 7,538.1 25,708.3 33,246.4 286.4 429.6 0.67 2.67 12-14-77 0.32 1,138.8 13,087.8 14,226.6 102.5 133.4 0.77 0.06 5-2-78 1.55 92.1 1,785.4 1,877.5 3.7 5.3 0.70 0.09 6-20-78 0.62 25.1 799.8 824.9 1.7 1.3 1.34 0.45 8-23-78 2.10 16.0 958.0 974.0 0.4 - - - 10-30-78 2.24 3.3 958.0 161.3 0.2 0.3 0.67 0.30 (D) 10-27-77 1.39 2.5 20.3 22.8 nd 0.2 - - 11-30-77 2.88 1,388.8 6,258.1 7,646.9 49.3 83.9 0.59 1.79 12-14-77 1.17 47.0 922.1 969.1 6.0 6.7 0.90 0.03 5-2-78 1.75 74.0 923.0 997.1 1.2 1.7 0.70 0.26 8-23-78 1.68 6.8 513.0 519.8 - - - - 10-30-78 1.79 2.5 65.5 67.0 - - - - (G) 10-27-77 1.89 2.7 79.7 82.4 0.2 0.05 3.5 - 11-09-77 1.17 706.7 2,002.0 2,708.7 14.2 43.9 0.32 1.6 12-14-77 0.96 86.5 688.8 775.3 5.6 7.0 0.80 0.3 5-02-78 0.39 53.9 1,399.5 1,453.4 4.2 6.3 0.66 0.06 8-23-78 1.71 66.0 687.0 753.0 6.6 10.1 0.65 0.16 10-30-78 2.12 1.9 50.5 52.4 0.1 - - 1.3 (B) 11-09-77 3.16 1,126.6 2,976.1 4,102.8 29.7 59.0 0.50 1.67 12-14-77 1.14 267.2 2,187.2 2,454.4 19.5 29.1 0.67 0.06 5-2-78 1.40 61.9 1,558.6 1,620.5 3.9 6.4 0.61 0.10 (E) 11-09-77 2.36 123.7 653.3 777.0 11.1 15.3 0.73 0.66 12-14-77 1.31 177.9 1,911.4 2,089.3 23.1 29.2 0.79 0.06 5-2-78 1.06 45.5 1,166.3 1,211.8 5.2 7.3 0.70 0.07 (F) 11-9-77 0.90 574.9 1,328.0 1,902.9 21.0 50.5 0.42 0.53 12-14-77 0.89 92.9 1,012.7 1,105.6 9.7 13.5 0.72 0.03 5-2-78 0.86 42.7 1,150.4 1,192.1 3.1 4.9 0.64 0.09 (I) 11-9-77 2.29 338.3 1,651.1 1,989.4 21.3 31.9 0.67 0.64 (J) 11-2-78 2.81 1.3 12.2 13.5 - - - - (Control ) TSESIS oil — — -., — — — "~ 0.54 7.0 UCM=unresolved complex mixture; PRIS=pristane; PHY=phytane; ALK/ ISO n-alkane-to- isoprenoid ratio over the range n-C,. no (see also Table 11.5). — 1 j— lo 226 TABLE 11.2 AROMATIC HYDROCARBON GROSS PARAMETER CONCENTRATIONS IN MYTILUS EDULIS DATE F2 (AROMATICS) SAMPLE RESOLVED UCM TOTAL (O 10-27-77 1.7 14.8 16.5 11-14-77 456.6 16,917.9 17,374.5 12-14-77 297.5 21,275.0 21 ,572.5 5-02-78 18.9 1,394.0 1,412.9 6-20-78 5.6 461.7 467.3 8-23-78 2.8 106.0 108.8 10-30-78 14.0 426.8 440.0 (D) 10-27-77 2.5 46.0 48.5 11-30-77 141.4 3,689.1 3,830.5 12-14-77 11.7 852.9 864.5 5-02-78 7.3 478.0 485.3 8-23-78 2.8 56.7 59.5 10-30-78 5.8 110.4 116.2 (G) 10-27-77 8.5 210.0 218.5 11-09-77 99.6 6,236.7 6,336.3 12-14-77 2.4 470.3 472.7 5-02-78 12.3 1,366.3 1,378.6 8-23-78 7.8 86.1 93.9 10-30-78 5.0 48.5 53.5 (B) 11-09-77 174.7 4,636.6 4,811.3 12-14-77 47.6 2,057.4 2,105.0 5-02-78 23.4 894.1 917.5 (E) 11-09-77 1.9 858.0 859.0 12-14-77 20.2 2,297.1 2,317.3 5-02-78 44.8 1,418.8 1,463.6 (F) 11-9-77 68.0 3,015.0 3,083.0 12-14-77 7.9 1,620.0 1,627.9 5-02-78 12.2 1,053.1 1,065.3 (I) 11-09-77 9.8 2,400.1 2,409.0 (J) 11-02-78 3.3 12.3 15.6 (Control) 227 TABLE 11. 3 CONCENTRATIONS OF AROMATIC HYDROCARBON COMPOUNDS IN MYTILUS EDULIS AS DETERMINED BY GC/MS NAPHTHA- PHENAN- DIBENZO- LENES THRENES THIOPHENES STATION DATE ( pq/g ) (yg/g) ( yg/g) (F) 11-09-77 32.3 24.5 _a 12-14-77 ndb 3.2 - 5-2-78 nd 1.6 - (D) 11-30-77 23.2 31.7 - 12-14-77 0.1 7.9 - 5-2-78 0.03 0.6 0.5 8-23-78 0.15 0.08 - 10-30-78 0.005 0.17 - (B) 11-09-77 79.2 61.3 34.3 12-14-77 3.4 14.0 14.1 5-2-78 0.3 1.7 1.0 (G) 10-27-77 (Baseline) nd 1.2 0.71 12-14-77 0.82 5.4 1.8 10-30-78 0.23 0.13 - (I) 11-09-77 0.7 16.91 - aNot searched . bNone ■ detected. 228 •J a < Eh O r c 50 i < a * i e u X en tn c o 4 o © o (- a a o p- a a o •» © © © © — in rt in rfi o -* © p* »n> q rt a r» r« c O O © © *0 c« to Quti«©ooo I ^^ctooTJ^inoo*P»'**PT3^pi -■ t c • • • • c e c.. U | r^ a o o o © o* — « o co ©in •» i»> © — ^ — ■OOOIS'O-*©* C • C • • C c r« o o oouto© ■-J CN ^ Z irt o ^ o *n p* p* p» pi I tj . "O is "o • t: • • • • "o • »3 tj o I co»cecocoo^oeoceo *> — as c* Z I Tar-^wooTJ — ©p»mp«o'3*5>^ <~> ' c • c c • • c ccc U i t o o o o — © o —i t as © 10 Z "0^-0^o,p}TJ'—o©p*,rJa»^^^ — ' CCCC • C C • • • • c -ccc CJ © o O r-t p* © I p» »■* ^ p- o> r* o © o •PJ^3000^^©OP*w1-*«rt^^^ ©OCT o a o o o < o f- c u > z a -J o u < o !- < m^uipii/ir^wir-mpiomowrtc* oo^moNi0o»r«<-t«M in h n r> in « — — c-. e •« I « as m so •» o © — « 01 QJ c G aj QJ i— i Xi ca ft .n O ■ M 4J •H 0) _n r" E p. ^J 01 CO o £\ C N c. c o -H QJ •H >.X) s: ' x: •H 4-1 u Tl o qj N E 1! C •H QJ U H -C 4-1 CO •H Q -a a i— i c QJ >> 0) c ~ i— i 01 w cO Sj 0) x: XI B 4-1 4-1 •H x: G S-l a. CO 4-1 crj c c QJ r. x: 0J rH a C L >> 01 ■z i— i G u >^ C^ cu j: o R 4-1 •H •H 0) ^C! X) i: 4J | •H o I S-J N QJ 4J a c QJ QJ *s XI 1—1 QJ •H cfl G XI J= 0) , 4-1 M i— 1 1 XI X! >, 1 P- 4J — 1 CO C 4J 1 C! CI) 0) g E • ^ 0) •H — 1 ! >-. -- T5 u • x c_ i-i ! u » CJ QJ i-H 0) 01 E >^ c 4-1 I X! 0J OJ i N 4-1 x: X) 1 QJ c. 1 <3 F^ o 0) c-OH •H c ! U XI g o i 4J G « •> o 3 0) N II CMC a CJ a QJ X) S-i ^3 c J ~ ^ •H ► *~7 4J •n • •1 ! ^c G CJ CO i—l 3 c >% )-i • ri QJ -C QJ g 4J w C ft 01 ^~* 1 0) B *-«. •»r.«o>ap«i-»or»«lo»oe.r.« |cO>^ll O J J r»" ei w? a.' r.' m' -' r>* rJ o p-' «' » I XI XI m " r.-w«w> — I4J4-JHC _ - ; x; o) cq -h ^ p: ! ct e q-x, lp» ojp^r^r-p-'p^ 'p* p* O I I P4 P« I I © O P» e> 1 c^ a O 7 - 1 1 ? o 1 CD 1 r. i o i II ft - o ZUffl IJ o •-, (-1 I ,_H r-M Q 01 « !N Jl •• ft CJ >■> CM 4J Q) t_3 - 0 /— N ^— V ^— N W H C CQ t^ H « CQ \~s ^— ' s_^ ft Q II CJ CJ -K 229 in living tissue exceed 30 mg/g at the most heavily impacted station C. Animals at the other shoreline stations D and E contain aliphatic hydro- carbon levels of 7.6 mg/g and 4.1 mg/g respectively during the November 1977 sampling. These values are 300 to 500 times the background hydro- carbon levels in tissues from these stations. Although depuration of aliphatic hydrocarbons appears to commence very soon after the initial impact in animals surviving the oil's landfall, it is not until 1 year after the event that tissue hydrocarbon levels appear to reapproach the background levels. However, examination of the detailed hydrocarbon composition of the tissues 1 year after the spill still reveals petro- leum hydrocarbon inputs at some stations. This will be discussed. High resolution gas chromatograms of the tissue hydrocarbon com- positions reveal a rapidly changing suite of hydrocarbons in the mus- sels. Initially, tissues from the most heavily impacted stations appear to have taken up hydrocarbons very similar in composition to the spilled oil (Fig. 11.2a and 11.2b). However, all samples obtained in December, 2 months after the spill, reveal GC patterns indicating substantial alteration of the cargo oil pattern, with n-alkanes being preferentially degraded compared with corresponding branched and isoprenoid compounds (Fig. 11.2c and 11. 2d). At several stations, most notably I, even the November tissue samples already exhibit notable preferential n-alkane degradation throughout the entire boiling range of the oil (approxi- mately n-C,- through n-C„n). The GC of Fig. 11.2c illustrates such a case, where the isoprenoid hydrocarbons, having retention indices of 1370, 1460 (farnesane), 1560, 1650, 1710 (pristane), and 1812 (phytane), become chromatographically prominent due to their greater resistance to microbial degradative processes (Kator, 1973). The rapid alteration in the tissue hydrocarbon composition from an essentially unaltered oil to an n-alkane-depleted, isoprenoid-enriched assemblage is the single most important aspect of the changing hydro- carbon chemistry of Mytilus tissue. This change is expressed in Table 11.1 as the ALK/IS0 ratio, which is simply the ratio of n-alkane to isoprenoid hydrocarbons in the n-C10 to n-Clc, boiling range. In the 1 J lo spilled cargo oil the n-alkanes predominate (ALK/ISO = 7.0). The most 230 Figure 11.2 Representative Glass Capillary Gas Chroma tog rams of Mytilus edulis Aliphatic Hydrocarbons A - Baseline (pre-spill) B - TSESIS cargo C - November (Station B) D - November (Station I) E - December (Station B) F - May 1978 (Station B) G - October 1978 (Station C) CH = cholestane (internal standard); n- C^ = n-alkane having x carbon atoms; FA = farhesane; PR = pristane; PH = phytane; UCM = unresolved complex mixture; 1370, 1460, 1650 = retention indices of these peaks 231 910 HD-N A i 1 -f ■=»^ -** . > — ? 09»l T A ; 232 heavily oiled samples exhibit an ALK/ISO ratio from 1.7 at station B to 2.7 at C, both in early November. Thus, even at the earliest sampling period the petroleum hydrocarbons already exhibit an altered pattern. Hydrocarbon GC profiles from particulate material in the water column in the region obtained from sediment trap deployments (see sec- tion on sediment traps) indicate that the oil sampled in the water during the first week in November also has been dramatically altered (see Fig. 11.6), presumably due to microbial degradation. Even the earliest trap samples obtained exhibit a degraded pattern (ALK/ISO = 1.0) and within 10 days all of the remaining oil dispersed in the water column has been severely altered (ALK/ISO = 0.1). As previously mentioned, the gross hydrocarbon parameters indicate that Mytilus remaining in the region have eliminated most of the initial hydrocarbon burden 1 year after the spill and pre-spill levels are being approached (Table 11.1). However, GC profiles (Fig. 11. 2G) of samples taken from station C in October of 1978 still exhibit significant levels of petroleum hydrocarbons albeit a degraded assemblage consisting mainly of UCM material. 11.3.1.2 Aromatic Hydrocarbons After receiving an initial hydrocarbon tissue burden at levels of 5 mg/g to 20 mg/g at the most heavily oiled stations, levels in Mytilus decrease but remain at levels 100 times the background levels of the gross parameters (Table 11.2) 7 months after the spill. One year after the spill levels appear to approach background at all stations except the most heavily impacted station, C. However, a close examination of the gas chromatographic profiles of representative aromatic hydrocarbon fractions throughout the year reveals that residual petroleum material is still present in the tissues one year after the spill (Fig. 11.3). Therefore the gross hydrocarbon parameters (Table 11.2) can be mis- leading without a consideration of both the GC run and the detailed aromatic hydrocarbon composition. The latter was determined by sub- jecting a set of samples for combined gas chromatographic/mass spec- trometric analysis and quantifying individual aromatic compounds which are otherwise obscured in the GC run due to their low levels relative to the entire suite of aromatic compounds. 233 Figure 11. 3 Representative Glass Capillary Gas Chromatog rams of Mytilus edulis Aromatic Hydrocarbons A - Baseline (pre-spill, Station C) B - TSESIS cargo C - November 1977 (Station B) D - December 1977 (Station C) E - May 1978 (Station B) F - October 1978 (Station C) G - October 1978 (Station G) TMB = substituted trimethyl benzene HEB = hexaethyl benzene (internal standard; 234 J Bm — — «v, em — J em 7 J \ _> ■? / -t BWJ. — \ A j j j ; Nl= — ^^-^=~ *~ .. NJ3 *"* '^ kS INJ 3N3TWMlHdVN — / 235 As can be seen in Tables 11.3 and 11.4, levels of individual hydro- carbon compounds initially as high a UO fJg/g decrease rapidly to the 3 |jg/g to 10 pg/g level in December and to the 0.1 (Jg/g level in October of 1978. It is interesting to note that one of the baseline or pre- spill samples (station G) contains significant quantities of substituted phenanthrenes as well as the organo-sulphur compounds, the dibenzothio- phenes. These are probably the residual aromatics from previous pollu- tion events. The other baseline sample from station D also exhibits small quantities of substituted aromatics (see Fig. 11.3a) as well. After one year (October 30, 1978) it is apparent that pre-spill levels are being approached, although the detailed aromatic composition does not mirror the pre-spill composition; i.e., one year after the spill mussels still contain substituted naphthalenes whereas the pre-spill samples contained none. As was the case for the aliphatic uptake patterns, the aromatic uptake profiles reveal temporal changes. On an absolute basis all aromatic components appear to have decreased substantially during the first month of post-spill depuration (Tables 11.2 and 11.4). On a comparative basis consider Fig. 11.4. Samples obtained after the first two weeks, post-spill, exhibit a slightly altered aromatic composition vis-a-vis the spilled oil. Soon thereafter the biphenyl and fluorene compounds decrease to non-detectable levels (May 1978) in the tissues and remain so until biphenyl reappears in tissues and, with the naph- thalenes, assumes a prominent comparative importance one year after the spill. It should be noted that Fig. 11.4 presents the data on a com- parative basis with the absolute sum of the total components in Fig. 11.4 decreasing throughout the year from 165.4 (Jg/g to 0.7 M8/S- During the year there appears to be a greater comparative loss of the naphtha- lenes, fluorene, and biphenyl, the lower boiling compounds, in addition to the parent organo-sulphur compound dibenzothiophene . The substituted dibenzothiophenes and substituted phenanthrenes are less readily depurated on a comparative basis. The aromatic hydrocarbon gas chromatograms also reveal a series of substituted trimethylbenzene (TMB) compounds that are relatively long- 236 Figure 11.4 Comparative Plot of Aromatic Hydrocarbon Composition of TSESIS Oil and Mytilus edulis Normalized to Trimethyl Phenanthrene N, C]N, C2N, C3N = naphthalene (N), methyl N, dimethyl N, trimethyl N BP = biphenyl F = fluorene DBT, CiDBT, C2DBT = dibenzothiophene (DBT), methyl DBT, dimethyl DBT P, C]_P, C2P, C3P = phenanthrene (P), methyl P, dimethyl P, trimethyl P 237 O! — 01 o> a. cr D fv *S a 5> d <; *r =. — S^Sm U) N« * CI 0 * ™ V> > _ O E «» « W S 7 CD Z 2 OS - o5£5££ou C/i tr ** ** W5 tfl > .r >• _> > h K S H S S S 238 lived in the tissues. The structures of these compounds were examined by GC/MS. A selection search for m/e=133 (Fig. 11.5) shows that the series is present in the Tsesis oil although in relatively small amounts. However, the series emerges rapidly, presumably due to its retention by the organisms or due to difficulty in biotransformation, and persists until 1 year after the spill when analyses fail to reveal significant quantities of TMB compounds. 11.3.2 Sediment Traps The material collected in the sediment traps at Stations II, IV, and V contains large amounts of weathered Tsesis cargo oil. Concentra- tions of Tsesis oil in the traps are presented in Table 11.5 and illu- strate that the rate of deposition of oil through the water column is similar at the upwind station (IV), at the wreck site (II), and downwind in the direction of the movement of the visible slick (V). Thus, it appears that oil is dispersed in the water column, adsorbs to detrital material, is quickly weathered, and is redistributed by subsurface water movement through the study region. The petroleum hydrocarbon deposition rate was high during the second week after the spill (.November 1 to November 9) and presumably was as high or higher during the last week in October. Thereafter the amount of petroleum hydrocarbons in the sedimen- ted material decreased markedly and 1 to 2 months afterward the spill reached very low levels. At these low levels, petrogenic hydrocarbon inputs are non-detectable. Very significant in terms of interpreting benthic as well as inter- tidal bivalve uptake patterns, are the detailed gas chromatograms of the hydrocarbon material found in the traps. As illustrated in Fig. 11.6 and 11.7, the spilled Tsesis oil that is sedimented has been significant- ly altered as early as 1 week after the spill. In the aliphatic fraction (Fig. 11.6), the n-alkane degradation has altered in oil's composition, presumably by microbial agents, to the point where the ALK/ISO ratio is 0.3 to 1.0, down from an initial value of 7.0. In addition, the increased importance of the UCM in these early deposition samples is evident from Fig. 11.6. 239 Figure 11.5 GC/MS Searches for Substituted Trimethyl Benzenes (TMB) A - TMB (m/e 133) searches on respresentat ive Myt ilus and Macoma samples B - Display of m/e 133 search and total ion chromatogram !40 TRCTETHYL BENZENES TSESIS C*«GO OIL . IVi A..L -i. JiA^Lj ■ © 0 CH3 I RHjC — CH ■ CH3 -CH2 -0- CH. 1 R-H 2 R-CH3 3 rh:htch2 4 R-O^CHj-CHj m/t-133 1 1 1 1 11 1 11 1 »i 1 1 1 11 1 1 1 1 1 1 1 1 1 n 1 1 111 1 n 1 1 1 1 1 1 1 1 1 1 11 ii n I mi 11 in 1 1 1 11 u 1 s ia is aa ss 3e s & 4S 52 S SB S 241 TABLE 11.5 SEDIMENT TRAP HYDROCARBON DATA DATES ALIPHATIC HYDROCARBONS (lig/g) AROHATIC HYDROCARBONS (ug/g> STATION RESOLVED UNRESOLVED TOTAL CPIa AKL/ISOb RES. UNRESOLVED TOTAL V NOV 1 - NOV 9 333 3,276 3,609 0.9 1.0 32 3,624 3,656 NOV 9 - NOV 17 32 907 939 1.1 0.1 5 1,129 1,134 NOV 17 - DEC 4 20 396 416 1.4 <0.05 3 424 427 II NOV 2 - NOV 9 129 1,331 1,460 1.0 0.5 53 3,266 3,319 NOV 9 - NOV 17 94 1,35C 1,444 1.2 0.2 18 1,354 1,372 NOV 17 - DEC 21 5 106 111 2.7 <0.05 2 76 78 IV NOV 2 - NOV 9 102 1,783 1,185 1.0 0.3 24 2,730 2,754 NOV 9 - NOV 17 G 20 26 1.5 <0.05 3 34 37 NOV 17 - DEC 21 40 30 70 2.5 <0.05 6 28 34 aCPI - Carbon Preference 2( n-C27 + n-C„) Index - n_c 26 * 2n -C28 * nC30 h«, u normal alk anes n"C14 * n-C15 f n-C16 + n-C1? + n- C18 ' Isoprenoids 1470 + 1560 + 1650 + 1710 + 1812 whore 1470 » farneaane, 1710 - prlotane, and 1812 » phytane. 242 Figure 11.6 Representative Glass Capillary Gas Chromat ograms of Sediment Trap Aliphatic Hydrocarbons A - TSESIS oil (November 2 - November 9) B - Station IV (November 2 - November 9) C - Station V (November 1 - November 9) D - Station V (November 9 - November 17) 243 J ■y. cid-n Ot£t CID-N SJ 244 Figure 11.7 Representative Glass Capillary Gas Chromatograms of Sediment Trap Aromatic Hydrocarbons" A - TSESIS oil B - Station II (November 2 - November 9) C - Station V (November 9 - November 17) 245 246 Just as the ALK/ISO ratio describes the chromatographic composition of the ii— C , „ to n-C10 range, the carbon preference index (CPI) describes i j io the nature of the n-C , to n-Cor. range. Aikanes within this range can Zo jL) indicate a petrogenic input (CPI = 1.0) or, as the CPI increases above 1, it documents an increased input of terrigenous n-alkanes having their source in vascular plant waxes (Farrington and Meyers, 1975). With increasing time, the hydrocarbon material sedimented in the region more closely reflects these normal terrigenous inputs (Table 11.5), thus illustrating that direct petroleum deposition appears to occur only during the early post-spill period, perhaps on the order of 0 to 3 weeks. Thereafter, it is possible that deposition continues outside of the three station transects due to the slick movement. The changes in the character of the aromatic hydrocarbon composi- tion of the trap material are illustrated in Fig. 11.7 and 11.8. The GC profiles of the aromatic composition (Fig. 11.7) indicate that the amount of the resolved material decreases relative to the whole oil and, as was the case with the aliphatics, the UCM achieves a chromatographic significance. This was observed in the November Macoma and December Mytilus GC profiles as well. However, unlike the aliphatic hydrocarbon changes which appear to be microbially mediated, changes in the aro- matics appear to depend on solubility considerations, the lower boiling compounds being preferentially lost. The total amount of resolved material decreases rapidly (Tables 11.5 and 11.6). However, on a comparative basis, consider Fig. 11.8 which, like the corresponding consideration of the Mytilus and Macoma data, indicates preferential loss of the soluble naphthalenes, biphenyl , and fluorene compounds, and soon thereafter the dibenzothiophene parent compound (see also Table 11.6). Microbial activity would result instead in loss of or conversion of the methyl side chains in the various homo- logous series. The composition of the aromatic hydrocarbons in the traps is severely altered by the third week after the spill and consists mainly of the phenanthrene series and substituted dibenzothiophenes . 247 Figure 11.8 Comparative Plot of Aromatic Hydrocarbon Composition of Sediment Traps and TSESIS Oil Normalized to Trimethyl Phenanthrene N, C]N, C2N, C3N = naphthalene (N), methyl N, dimethyl N, trimethyl N BP = biphenyl F = fluorene DBT, CiDBT, C2DBT = dibenzothiophene (DBT), methyl DBT, dimethyl DBT P, CiP, C2P, C3P = phenanthrene (P), methyl P, dimethyl P, trimethyl P 248 249 CD < a, a. S! M cl col Ml I fa! 2' C °! si °! u! 21 O1 CD a i ! c i 2 CM u a CO a a a m a a. z O I r— r» r-i «h m m o i> CO -« O rH «-4 o ■ • • — i o — < — I o ■» *n n ^ ui o r» rs ^ -< o #-» o in r>t CM O O CO «— t o o o o u z Ul — J > t? < J v. f- O O- O in — t- w — BS to u < < o in o > O z a > O z > o z > o z > o z > o z > o z oi >. -' c JZ 41 CJ JJ E —1 a -m 03 g u £ ±> jj *o js M a •> e c 4J c c C OJ 41 w »H " JS >. Q..W JB 0 C JJ — * «J t> J= e E jj t> — * 0 .cc » N c. XI c «.' ^* » J3 > V — * JZ C -D aj 01 o »H «-» e C >. — * J3 .Z "0 U j-» JB n ~ a e 41 •3 e C ~ « CJ w .— > C JZ > u JJ g JZ c JJ a. a HJ 0 c E — « CJ — * J= jz "C 4J 0 a c b t/i ! U O 1 u. > ►- m o c >. c OJ JZ CJ — JJ « ^j e u i > jr oj cf< c cagi COW >• c JC . « *J H C OJ CD ft! e q j= -iO. CJ I c « 4J r- O. « a u .c cj a. a c oi u c u o » i 3 a. »-i ^^ z >~> o n u » » 03 .J C 2 £«. - 3 r* OJ w (J — C — 01 » >iX • ;cu -<4> 0 C ur- » C= 1- » 0 jj j: Z — O JJ (V J2 N C C H) II Oi C — 0J a — ■ jz a t c 250 11.3.3 Surface Sediments Initially 15 sediment samples covering the entire region were analyzed by glass capillary gas chromatography and several subjected to GC/MS analysis for detailed aromatic hydrocarbon determinations. Al- though several different suites of hydrocarbons were observed in the extracts (see Fig. 11.9 and 11.10), no petrogenic inputs were observed that related to the spilled Tsesis oil. The UCM was a prominent feature in most of the chromatogranis . The UCM material is generally ascribed to anthropogenic inputs from several possible sources, including urban particulates (Hauser and Pattison, 1972) and weathered petroleum from storm runoff, municipal sewage, and chronic oil spills (Van Vleet and Quinn, 1978; Boehm and Quinn, 197S; Famngton et al., 1978) and is observed in most silt/clay surface sediment in the region (Rudling, 197b) . The dominant feature other than the UCM, in the GC traces, was the terrigenous n-alkanes n-C0 , n-C , n-C0Q, n-C,,,, and their dom- inance over their even carbon number neighbors, yielding CPI values from 2.5 to 5.4 (Table 11.7). The absence of significant quantities of petrogenic hydrocarbons in the surface sediment (0 cm to 2 cm) was puzzling. It was hypothesized that the gravity corer used in the initial sampling might, on impact, blow away the fine floe layer, just on the sediment water interface, where newly deposited material resides. Also the depth of the sediment sampled (2 cm) might cause background levels of hydrocarbons (50 pg/g to 1,000 pg/g, Table 11.7) to obscure smaller quantities of petrogenic hydrocarbons (see also section 6.4.1). A careful resampling was performed at Station 20 with a wide-bore corer which presumably disturbed the surface layer less. In addition, two sections, the 0 cm to 0.5 cm and 0.5 cm to 1.0 cm layers, were obtained for analysis. Again, the analytical results indicate no petro- leum in the sediment, with the possible exception of one 0.5 to 1.0 cm section, which indicates an input of lower boiling n-alkanes to the terrigenous assemblage (Fig. 11.9a). If this is Tsesis-related hydro- carbon material, then it has been significantly altered. 251 Figure 11 . 9 Representative Glass Capillary Gas Chromatograms of Surface Sediment Aliphatic Hydrocarbons A - Station 20 (0.5-1.0 cm) - 1, 29 November 1978 B - Station C, 20 December 1977 C - Station 20 (0.5-1.0 cm) - 2, 29 November 1978 !52 u I z u I z U o I ID 2 l 1 >i J U Ll li A i J \J^ b* >~~ L* ^ N U\ta^ u I z o n u w^U^W ilL «'. ! 253 Figure 11.10 Representative Glass Capillary Gas Chromatograms of Surface Sediment Aromatic Hydrocarbons Station 20, 8 March 1978 !54 a X jJWU-d Lt> Vu mi] UCM V 255 TABLE 11.7 HYDROCARBON CONCENTRATIONS IN SURFACE SEDIMENTS AS DETERMINED BY GC [ON DATE DRY WEIGHT ALIPHATIC HYDROCARBONS (yg/g) AROMATIC HYDROCARBONS (yg/g) stat: RESOLVED UCM TOTAL CPI RESOLVED UCM TOTAL (C) 11-24-77 3.02 3.3 23.0 26.0 3.3 1.0 21.8 22.8 12-20-77 2.37 9.4 71.2 80.6 3.3 2.8 78.4 81.2 (2) 11-24-77 2.43 3.1 72.5 75.6 2.9 0.9 12.9 13.8 (D) 11-24-77 5.02 2.7 24.2 26.9 3.2 0.4 3.1 3.5 12-20-77 2.58 4.1 20.2 24.3 2.9 0.4 9.4 9.8 (G) 11-24-77 1.32 7.0 16.3 23.3 5.4 2.6 38.9 41.5 (5) 11-24-77 4.97 3.1 39.6 42.7 3.8 2.2 25.4 27.6 12-20-77 4.53 2.1 35.8 37.9 3.5 0.9 6.8 7.7 (6) 11-24-77 2.31 3.8 28.4 32.2 3.8 1.3 6.8 8.1 12-20-77 4.33 2.7 6.2 8.9 4.3 - - - (7) 11-24-77 1.99 8.1 97.4 105.5 3.1 2.3 33.3 35.6 12-20-77 9.06 1.8 3.2 5.0 4.9 0.4 7.3 7.7 (8) 12-20-77 4.64 3.6 0.9 4.5 5.2 0.8 3.7 4.5 (20) 3-8-78 25.04 5.3 63.0 68.3 4.4 5.2 29.0 34.2 6-6-78 7.45 6.8 79.0 85.8 4.1 8.8 44.0 52.8 12-4-78 (0-0.5 cm) 2.59 4.3 56.9 61.2 3.2 11.7 68.3 80.0 12-4-78 (0-0. 5 cm) 1.09 9.8 155.5 165.3 3.3 28.0 75.1 103.1 12-4-78 (0.5-1.0 cm) 0.40 81.2 396.3 477.5 2.6 96.5 553.4 649.9 12-4-78 (0.5-1.0 cm) 2.22 18.6 105.0 123.6 3.2 17.5 44.2 61.7 12-4-78 (0-0.5 cm) 1.89 6.3 64.3 70.6 3.5 10.2 58.9 69.1 (15) 11-29-78 (0-1.0 cm) 1.66 5.0 20.5 25.5 2.5 4.5 16.8 21.3 256 The aromatic hydrocarbon GC ami GC/MS runs fail to indicate a chemical relation between either the spilled oil or the sediment trap material to the surface sediment. The GC trace of a typical surface sediment aromatic fraction is presented in Fig. 11.10 and shows mainly a series of large, unidentified biogenic peaks and some indication of a weathered petroleum input, as evidenced by small quantities of members of the phenanthrene homologous series (phenanthrene = 0.03 Mg/g> methyl phenanthrenes = 0.07 Hg/g, dimethylphenanthrenes = 0.03 Mg/g> triethyl- phenanthrenes = 0.02 (Jg/g) . 11.3.4 Macoma balthica Macoma balthica samples were obtained from the soft bottom at 8 Stations indicated in Fig. 11.1 and at a control station 15 located south of Asko Island. In contrast to the Mytilus edulis hydrocarbon contents, which show dramatic increases and rapid and near complete depuration over the course of a year, concentrations in this benthic deposit feeder show a rapid but modest concentration increase to the 500 to 900 pg/g level in the aliphatic fraction and 500 to 1,700 Mg/g level in the aromatic fraction. The initial uptake appears to be location- specific in contrast to the initial Mytilus behavior which is similar over the entire study area (see Table 11.1). The concentration infor- mation in Tables 11.8 and 11.9 indicates that while depletion of tissue hydrocarbon burdens may be occurring at stations D and 20 between November and December, for the most part Macoma continues to take up petroleum hydrocarbons with aliphatic hydrocarbon tissue levels clearly on the increase at stations 20 and 7 (.Table 11.8) and aromatic levels increasing at stations D and 20 after a winter decrease (.Table 11.9). Whether the depuration and re-uptake phenomenon is a function of reintroduction of petroleum-bearing particulates to these stations or can be attributed to aspects of the animals feeding rate and metabolic state is not apparent from the Macoma data or from sediment trap data which characterize sedimented material only through mid-December. The hydrocarbon levels in Tables 11.8 and 11.9 should be viewed in relation to the control (.station 15) levels. Furthermore, the August 257 o co M r- cn CXi 00 rr o o o o o o o CN ex i— IOi— lOOOOOr— I r» vd o o o cn i< joooooooooooooooooooooooooo < ! < u •J < I x)cor-ioLnoLnvDcOLrivor~cN r^aDi/iLno>v£)vrirHLr)oocDrHr^r~c^cNcocrNrHinir)Ocoinc3in^r~cocNcocNr^co''*rco >-h ] OC 'rovorooLD"*'— lOTLnr^^HfNirrc^Lna^tNOCNmaooc^i— (O cu ! -n CM CN CN (N X J CQ < Eh CO 2 O h-4 e-" < a! Eh X ° O! < xi Ql XI = l HI EH < a: ex •J < cr \ CT I ° ! ■= ! fa < Eh o Eh £ CJ D r~LOLnuococNuoco^cxcNr~r~cxuor~Lnv£>cor^ocor-~'3'r--co CO w X Eh XX-— eu tn Q M — W 3 Ed Eh < Q X X s: < CO iH r- o cn •"s- r^ cr\ cn rr in co CN-^r— ITCNf-OCXCOUDCN coHQMoininm^'*^ voincNoo^LnLnxs'rocNCN cn r» cn o -^ nn i— i ld CN cr\ cn o tn cn V£> r- *3- VD i-4 CN CO >>o r-i r~ r~ vo r- oo co co ra- in r-» r- cn i— i cor-cNOLncor^r^-TtncoLn CN CN O "=r CN r~ I O *X> rH o io^POCNr~vx>''3,vooocO'3,cNi— ir~-Lnr"> CJirHCTNOVOCOr^Or- I i— loe'ocnOrHf— i in co mrHCNCNinvCi'3,r- I i— ' CNCNrr-TOinncocri m o co t r~ CN "3" CN [*«■ v£> CN 00 VO rH O rHCOrHcr.inr~coLninocO'mcoinr~-incNcors-invo o co cn o o co rH r~ i— i co r~ vd o~\ co in cn l^> LD cNCTiLncooococoLncNCNCNr-rvivDoo^r moTfoocrir-if— icNr~-cNr»r- i^Tro^rvc ,— i (— i -^> rH CO r> I l CN VO r- l o co cn I I co I r- i CN V£> r- r~ i o r- l o m cn I l I o r- i o r- l p» o I m cn co I I l H (N VD r- I o r- co t I O CN ao oo I I CO 00 CO CO r- r- r~ r^ I i I n (N (N co vo I I I I I I I CN I r-i r-\ kD rH r-t rHCNCNmvOCDCOCOCN CO o CN o u c o 258 TABLE 11.9 AROMATIC HYDROCARBON GROSS PARAMETER CONCENTRATIONS IN MACOMA BALTHICA DATE F2 (AROMATICS) (iig/g) SAMPLE RESOLVED UCM TOTAL (C) 11-30-77 69.3 979.5 1,04b. 8 (7) 11-30-77 7.3 358.6 365.9 12-20-77 20.8 424.3 455.1 6-7-73 21.5 401.2 422.7 (D) 11-30-77 14.4 1,692.9 1,707.3 12-20-77 0.9 987. 2 988.1 6-7-78 40.8 1,031.9 1,072.7 (3) 11-30-77 33.0 721.9 754.9 12-20-77 7.2 397.3 404.5 6-7-78 35.7 385.6 421.3 (6) 11-30-77 37.5 763.4 800.9 12-20-77 29.5 940.8 970.3 (2) 11-10-77 5.9 530.2 536.1 6-7-78 16.3 140.8 157.1 (5) 11-30-77 11.6 759.1 770.7 12-20-77 34.5 1,259.9 1,294.4 6-8-78 22.0 526.1 548.1 (20) 11-30-77 28.1 1,248.5 1,276.6 12-20-77 55.5 1,123.4 1,178.9 2-22-78 13.1 595.5 608.6 3-8-78 28.1 458.5 486.6 6-6-78 31.4 344.8 376.2 8-17-78(a) 503.7 1,081.2 1,584.9 8-17-78(b) 282.9 1,382.4 1,665.3 8-17-78(c) 178.7 1,786.2 1,964.9 (15) 2-21-78 34.1 84.8 118.9 (control ) 259 1978 Ma coma sampling afforded the opportunity to determine the variation of gross parameter hydrocarbon levels within the population through triplicate analyses. In the aromatic fraction the resolved components exhibit a coefficient of variation of ± 51.6 percent (x = 321.8 |.ig/g ± 165.9) but the total concentrations varied by ±11.5 percent (x = 1,738.4 |jg/g ± 200.3). The corresponding aliphatic hydrocarbon data yield values of ±17.7 percent (x = 165.6 fjg/g ±27.1) and ±16.4 percent (x = 1,618.8 |.ig/g ± 287.0) for the resolved and total gross parameters. The apparent reintroduction of petroleum hydrocarbons to the ben- thic environment is dramatically seen in the station 20 Macoma values. Initially, the Macoma population at this station received a petroleum input. This is shown in the high pristane and phytane levels in the tissue (Table 11.8) as well as the high levels of naphthalene and phenanthrene compounds (Tables 11.9 and 11.10) in the tissues. However, by the time of the first sampling (November 20 to November 30) what remains in the tissue has taken on the degraded oil composition, featuring relatively enhanced levels of the isoprenoids (Table 11.8, ALK/IS0 ratio; Fig. 11.11) and the branched alkanes. Indeed this alkane-depleted GC pattern, common both to the second Mytilus sampling (December 14) and to some extent even the November Mytilus group (see Fig. 11.1b), as well as the sediment trap material (Fig. 11.6b), is also common to the Macoma populations in the entire impacted region. Samples from the control station 15 do not exhibit this profile but instead reveal indications of weathered petroleum in a higher boiling UCM over- ridden by small resolved components. It is not known whether an earlier Macoma sampling (e.g., early November) would have yielded a fresher, less degraded petroleum input. However, judging from the sediment trap chromatrograhic profiles, which indicate that sedimented material col- lected in early November already showed that the aliphatic hydrocarbon composition had been drastically altered, it can be hypothesized that little or no unweathered petroleum reached the benthos. By contrast, relatively unweathered petroleum impacted the littoral zone, but ex- posure to fresh oil even in this zone was short-lived. 260 TABLE 11.10 CONCENTRATIONS OF AROMATIC HYDROCARBON COMPOUNDS IN MACOMA BALTHICA AS DETERMINED BY GC/MS NAPHTHA- PHENAM- DIBENZO- LENES THRENES THIOPHENES STATION DATE ( ug/g ) ( ug/g ) ( yg/g) (20) 11-30-77 3.0 22.0 7.4 12-20-77 1.3 24.6 _a 03-08-78 0.2 3.9 5.1 06-06-78 ndb 0.8 - 08-17-78 0.5 2.7 2.3 (5) 11-30-77 2.7 15.0 7.8 12-20-77 3.6 10.8 2.5 06-08-78 nd 1.6 - (2) 11-10-77 0.4 2.1 - aNot searched . bNone detected • 261 Figure 11.11 Representative Glass Capillary Gas Chromatograms of Macoma balthica Aliphatic Hydrocarbons (Station 2C ) A - TSESIS oil B - November C - December D - March 1978 E - June 1978 F - August 1978 262 3 2 O091 -% * ~ !fe- 263 Hydrocarbon levels in Ha coma first increase relative to control values, then decrease, and in June through August begin to increase again. Throughout the entire study period the aliphatic hydrocarbon compositions, as revealed by GC profiles, remain more or less the same with the branched alkane, isoprenoid compounds and unresolved complex dominating. This is true through August. That fact, coupled with the increase in absolute concentrations, indicates that weathered petroleum remains in the benthic system and is apparently resistant to further rapid degradation. Thus the chromatograms in Fig. 11.11 reflect this constancy in aliphatic hydrocarbon composition. Data on the aromatic hydrocarbon levels at Station 20 (Table 11.10) also reveal a winter decrease followed by a summer reintroduction. Chromatographic profiles (Fig. 11.12 and 11.13) illustrate that the lower boiling compounds naphthalenes, biphenyl, and fluorene are de- pleted initially in tissue relative to the spilled oil, but in winter the relative aromatic composition is most like the sediment trap samples (Fig. 11.13) with the lighter end being more weathered. Although lower in absolute concentrations by August, the aromatic composition in the tissues remains generally constant throughout the study period (Fig. 11.12). As was the case in the Mytilus samples the presence of the tri- methyl benzene (TMB) series plays a prominent minor role in the aromatic hydrocarbon chemistry of Macoma throughout the study (Fig. 11.12). Buried in the overall Tsesis oil chromatograms, the TMB series emerges as other resolved components weather, indicating an interesting resis- tance to degradation both within the animals and in particulate or sedimented material comprising their food. As was the case for Mytilus , the TMB series is not present in the pre-spill or control environments. 11.4 Discussion From the previous presentation of the analytical results of this year-long study one can piece together the chemical fate and effects of the Tsesis oil spill on the marine environment in the region. 264 Figure 11.12 Representative Glass Capillary Gas Chromatograms of Macoma balthica Aromatic Hydrocarbons (Station 20 ) A - TSESIS oil B - November 1977 C - December 1977 D - March 1978 E - June 1978 F - August 1978 265 / ■*» J -^ .1 y ■* > D *2* (N)3N3TVM1M<(VN ~^.< 1 26' Figure 11.13 Comparative Plot of Aromatic Hydrocarbon Composition of TSESIS Oil and Macoma balthica Normalized to Trimethyl Phenanthrene N, C]N, C2N, C3N = naphthalene (N), methyl N, dimethyl N, trimethyl N BP = biphenyl F = fluorene DBT, CiDBT, C2DBT = dibenzothiophene (DBT), methyl DBT, dimethyl DBT P, CiP, C2Pf C3P = phenanthrene (P), methyl P, dimethyl P, trimethyl P 267 268 About 1,100 metric tons of oil were spilled in the region and about 700 tons were recovered during cleanup operations. The oil was driven by the prevailing winds to the northeast and, as a largely unweathered oil slick, impacted the coastline at stations D, B, C, and F. Here the littoral zone was severely impacted from a community standpoint (section 7). Concentrations of petroleum hydrocarbons in tissues were as high as 20,000 to 50,000 (Jg/g and at this level mortalities seem to have occur- red (section 7.2). As the slick passed through the region, significant quantities of petrogenic hydrocarbons were mixed into the water column and concentra- tions in the water as high as 50 \\g/ S. (greater than 100 times the back- ground levels) were observed (Boehm and Fiest, 1978). In addition, oil dispersed in the water column was sedimented to the bottom presumably through (1) adsorption to detrital material and sinking and/or (2) ingestion of oil droplets by zooplankters followed by fecal pellet transport to the benthos. Visual scrutiny of zooplankters obtained during the early stages of the spill demonstrated that oil had been in- gested by zooplankters in the water column (see section 4.3.4). Oil remaining at the water's surface apparently underwent only slow degradation due to chemical and microbial weathering until landfall occurred. However, petroleum material dispersed in the water column underwent rapid bacterial degradation of the aliphatic hydrocarbons with n-alkanes being rapidly depleted relative to the isoprenoid compounds and rapid removal of the lighter aromatic fraction due to dissolution. Measurements of the bacterial populations following the spill indicate an increase in the bacterial population in the water column possibly due in part to the availability of oil as a carbon source (see section 4.3.3). Those stations receiving secondary impacts of the spilled oil (i.e., those receiving a secondary landfall of oil), most notably sta- tion G (at first this was designated as a control station due to no obvious landfall of the spilled oil), received a degraded oil as seen in the Mytilus tissues due to the longer residence of this petroleum mater- ial in the water. 269 Uptake patterns of the hydrocarbon material indicate that rapid depuration of fresh oil characterized the Mytilus samples during the early months of the spill and throughout the following year degraded Tsesis petroleum was present in Mytilus tissues. One year after the spill, much of the petroleum was gone from mussel tissue except at station C from which samples continued to exhibit aliphatic and aromatic petroleum hydrocarbons in their tissues. This was presumably due to the greater initial exposure of the Mytilus population to oil at this station. Macoma, on the other hand, received a sizeable petroleum impact during the early stages of the spill probably due to direct sedimentation of the oil. After apparent depuration occurred during the winter, a secon- dary impact was observed, especially at station 20. The transport path of this secondary oil might include (1) landfall, (2) sinking at the shoreline with age, and (3) transport and redistribution throughout the 30-meter-depth basin of which station 20 is at the bottom. It is possi- ble that as the water temperature increased and pumping rates of both Mytilus and Macoma increased, the increased activity aided in the depura- tion of the former and recontamination of the latter. The station 20 location appears to be at the focus of the benthic impact of the spill which is observed at all benthic stations (station 2 west of Fifong Island included) except for station 15, the control station south of the island of Askb*. Macoma balthica appears to be an excellent indicator of pollutant input to the benthos. As was previous- ly suggested by Shaw et al. (1976), Macoma apparently receives material identical in composition to that captured in the sediment traps. It is puzzling why, even with careful sampling of surface sediment, the direct confirmation of the presence of oil in sediment is ambiguous at best. Bieri and Stamoudis (1977) were also unable to directly confirm the presence of fuel oil in sediment in their experimental oil spill in spite of its obvious presence in benthic organisms. The hydrocarbon material present in the fine floe at the sediment/water interface is difficult to sample even with careful grab or core sampling. Thus, the sedimented hydrocarbons from the Tsesis spill may reside at this diffi- cultly sampled, highly mobile pseudo-surface from which Macoma obtains 270 its food. This fact may also account for the drastic elimination of the important sensitive benthic crustacean, Pontoporeia spp . , from station 20, and its failure to reoccupy the station as of August 1978 (see section 6.3.2). The apparent contrasting behavior of Mytilus and Macoma vis-a-vis ingested oil may reflect more the duration of exposure and source trans- port route of the petroleum than any intrinsic differences in the two bivalve species. Depuration of acutely acquired hydrocarbons by Mytilus is apparently accomplished through flushing of water through the animal's gills. Other studies have shown that depuration of acutely acquired petroleum is fairly rapid though perhaps not complete (Fossato and Conzonier, 1976; Anderson, 1975; Kanter, 1974; Stegeman and Teal, 1973; Lee et al., 1972; among others). However, Boehm and Quinn (1978) and DiSalvo et al. (1975) have shown that chronically accumulated hydro- carbons are slow to be eliminated from bivalve tissues, thus suggesting that the duration of exposure is critical to the post-spill chemical recovery of a particular bivalve community. The transport and reintro- duction to and long resistance time of petroleum in the benthic environ- ment in the regions of the Tsesis spill may result in the much slower recovery of Macoma and the entire soft-bottom community from the effects of this spill, and in general points to the environmental complications caused by transport of petroleum to the benthos. 271 11.5 References Anderson, J.W. 1975. Laboratory studies on the effects of oil on marine organisms: an overview. Publication of the American Petroleum Institute 4249:1-70. Anderson, J.W., R.G. Riley, and R.M. Bean. 1978. Recruitment of benthic animals as a function of petroleum hydrocarbon concentrations in sediment. J. Fish Res. Bd. Canada 35:776-790. Bieri, R.H. and V.C. Stamoudis. 1977. The fate of petroleum hydro- carbons from a No. 2 fuel oil spill in a seminatural estuarine en- vironment, in D.A. Wolfe (ed.), Fate and effects of petroleum hydrocarbons in marine organisms and ecosystems. Pergamon Press, Inc. , New York, 332-334. Boehm, P.D. 1978. Hydrocarbon chemistry of Georges Bank and Nantucket Shoals, Inc. Final Report North Atlantic Benchmark Program, Bureau of Land Management, New York. Boehm, P.D. and J.G. Quinn. 1978a. Benthic hydrocarbons of Rhode Island Sound. Est. and Coast. Mar. Sci. 6:471-494. Boehm, P.D. and J.G. Quinn. 1978b. The persistence of chemically accumulated hydrocarbons in the hard shell clam, Mercenaria mercenaria , Mar. Biol. 44:227-233. Boehm, P.D. and D.L. Fiest. 1978. Analyses of water samples from the Tsesis oil spill and laboratory experiments on the use of the Niskin bacteriological sterile bag samples. National Oceanic and Atmospheric Administration Report Contract 03-A01-8-4178 , Boulder, Colorado. Clark, R.C., Jr. and J.S. Finley. 1974. Uptake and loss of petroleum hydrocarbons by the mussel, Mytilus edulis , in laboratory experi- ments. Fish. Bull. 73:508-515. Clark, R.C., B. Patten, and E.E. De Nike. 1978. Observations of a cold water intertidal community after 5 years of a low level, per- sistent oil spill from the General M.C. Meigs, J. Fish. Res. Bd . Canada 35:754-765. Conomos, T.J. 1975. Movement of spilled oil as predicted by estuarine non-tidal drift. Limnol. Oceanog. 20:159-173. Conover, R.J. 1971. Some relations between zooplankton and Bunker C oil in Chedabucto Bay following the wreck of the tanker Arrow. J. Fish. Res. Board Can. 28: 1327-1330. 272 DiSalvo, L.H., H.E. Guard, and L. Hunter. 1975. Tissue hydrocarbon burden of mussels as potential monitor of environmental hydrocarbon insult. Env. Sci. and Tech. 9:247-251. Erhardt, M. and J. Heinemann. 1975. Hydrocarbons in blue mussels from the Kiel Bight. Env. Poll. 9:263-281. Farrington, J.W. and P. A. Meyers. 1975. Hydrocarbons in the marine environment. In G. Eglinton (ed.), Environmental Chemistry, Vol. 1, The Chemical Society Special Report No. 35, London. Farrington, J.W. and J.G. Quinn. 1973. Petroleum hydrocarbons in Narragansett Bay I. Survey of hydrocarbons in sediments and clams (Mercenaria mercenaria) . Est. and Coast. Mar. Sci. 1:71-79. Farrington, J.W., N.M. Frew, P.M. Oschwend, and B.W. Tripp. 1978. Hydrocarbons in cores of Northwestern Atlantic coastal and continental margin sediments. Est. and Coast Mar. Sci. 5:793-808. Fossato, V.U. 1975. Elimination of hvdrocarbons by mussels. Mar. Poll. Bull. 6:7-10. Fossato, V.U. and E. Siviero. 1974. Oil pollution monitoring in the Gulf of Venice using the mussel Mytilus galloprovincialis . Mar. Biol. 25:1-6. Fossato, V.U. and W.J. Canzonier. 1976. Hydrocarbon uptake and loss by the mussel Mytilus edulis. Mar. Biol. 36:243-250. Grahl-Nielsen, 0., J.T. Staveland, and S. Wilhelmsen. 1978. Aromatic hydrocarbons in benthic organisms from coastal areas polluted by Iranian crude oil. J. Fish. Res. Bd . Canada 35:615-623. Hauser, T.R. and J.N. Pattison. 1972. Analysis of aliphatic fraction of air particulate matter. Env. Sci. and Tech. 6:549-555. Kanter, R. 1974. Susceptibility to crude oil with respect to size, season, and geographic location in Mytilus californianus (Bivalvia). University of Southern California Sea Grant Report, USC-SG-4-74: 1-43 . Kator, H. 1973. Utilization of crude oil hydrocarbons by mixed cultures of marine bacteria. In D.G. Ahearn and S.P. Meyers (eds.), The microbial degradation of oil pollutants. Publication No. LSU-SG- 73-01, Louisiana State University, Baton Rouge. Keizer, P.D., T.P. Ahern, J. Dale, and J.H. Vandermeulen. 1978. Residues of Bunker C oil in Chedabucto Bay, Nova Scotia, 6 years after the Arrow spill. J. Fish. Res. Bd. Canada 35:528-535. 273 Lee, R.F., R. Sauerheber, and A. A. Benson. 1972. Petroleum hydrocarbons: uptake and discharge by the marine mussel Mytilus edulis . Science 177:344-346. Mattson, J. and P. Grose. 1978. Impact assessment of the USNS Potomac oil spill. Interim final report, NOAA. Mayo, D.W. , D.S. Page, J. Cooley, E. Sorenson, F. Bradley, E.S. Gilfillan, and S.A. Hanson. 1978. Weathering characteristics of petroleum hydrocarbons deposited in fineclay marine sediments, Searsport, Maine, J. Fish. Res. Bd. Canada 35:552-567. Meyers, P. A. and J.G. Quinn. 1973. Association of hydrocarbons and mineral particles in saline solutions. Nature 244:23-24. National Academy of Sciences. 1975. Petroleum hydrocarbons in the marine environment. NAS , Washington, D.C., 1-107. Owens, E.H. 1978. Mechanical dispersal of oil stranded in the littoral zone. J. Fish. Res. Bd. Canada 35:563-572. Poirier, O.A. , and G.A. Thiel. 1941. Deposition of free oil by sediments settling in seawater. Bull. Amer. Assoc. Petr. Geol. 25:2170-2180. Rudling, L. 1976. Oil pollution in the Baltic Sea. A chemical analytical search for monitoring methods. Statens NaturvSrdsverk (Sweden) PM 783:1-80. Shaw, D.G., A.J. Paul, L.M. Clark, and H.M. Feder. 1976. Macoma balthica : an indicator of oil pollution. Mar. Poll. Bull. 7:29-31. Stegeman, J.J. and J.M. Teal. 1973. Accumulation, release, and retention of petroleum hydrocarbons by the oyster Crassostrea virginica . Mar. Biol. 22:37-44. Teal, J.M. , K. Burns, and J. Farrington. 1978. Analyses of aromatic hydrocarbons in intertidal sediments resulting from two spills of No. 2 fuel oil in Buzzards Bay, Massachusetts. J. Fish. Res. Bd. Canada 35:510-520. Van Vleet, E.S. and J.G. Quinn. 1978. Contribution of chronic petroleum inputs to Narragansett Bay and Rhode Island Sound sediments. J. Fish. Res. Bd. Canada 35:536-543. , Warner, J.S. 1976. Determination of aliphatic and aromatic hydrocarbons in marine organisms. Anal. Chem. 48:578-583. 274 Appendix 1 Investigations Appendix 1: Investigations PELAGIC INVESTIGATION l Station Date Depth Samples Samples for Degree of initial (1977) oil analyses oil impact 2 Pp Ph Z B S S I (ref) Oct 25 50 0 Nov 22 Nov 22-Dec 14 II Oct 28 23-25 Oct 29 Oct 30 Oct 31 Nov 02 Nov 02-09 Nov 09-17 Nov 17-Dec 21 III Oct 31 ++ IV: + V: + + + X X X X X X X X X X X X X X X X X X X IV & V Nov 01 IV: X Nov 02 30-32 X Nov 05 V : X X X X Nov 07 X X X Nov 09 25 X X X X Nov 11 X X X X Nov 14 X X X X Nov 17 X X X Nov 24 X Nov 02- -09 X X Nov 09- •17 X X Nov 17- -Dec 21 X X VI (ref.) Oct 26 36 X X X X Nov 09 X X X X Nov 23 X X X X Nov 09- -23 X Nov 23- -Dec 14 X Echosounding for fish in Svardsf jarden was also undertaken on Nov 11 and Dec 15 1977, and Jan 11 and Apr 12, 1978. During the period 13-29/6, 1978, herring eggs were collected in the impacted area for laboratory experiments on hatching success and compared with eggs collected between 13/6-6/7 from an unpolluted area west of Asko Laboratory. Pp = Primary production 0 = none Ph = Phytoplankton + = light Z = Zooplankton ++ = moderate B = Bacteria +++ = heavy S = Sedimentation 277 PHYTAL INVESTIGATION Station Date Depth Sampli 2S Samples for Degree of initial (m) en 3 oil analyses oil impact u 3 En C •H CJ ctf g T3 D u ffl £> R) i.J CD 6 a, a Cfl 4J C CO cr to ■H ■-I 3 T3 01 a ■u c e ■H s analyses ■u C 0) e • H •3 01 CO oil impact D (cont) May Jun Jun Aug Aug Oct 02 13 20 23 28 30 '78 M II II II 11 P 1-2 rof ile 1-2 II ti 11 X X X X X X X X +++ E Nov Nov Dec May Aug 09 10 14 02 28 '77 II It '78 II P 1-2 rof ile 1-2 II 11 X X X X X X X X F Nov Nov Dec May Aug Oct 09 10 14 02 28 30 '77 II 11 '78 11 II P 2 rof ile 2 tl H It X X X X X X X X X + G Oct Nov Nov Nov Nov Nov Nov Dec May Jun Jun Jul Aug Aug Oct 27 02 02- 09 14- 16- 24 14 02 14 20 05 23 28 30 03 15 17 '77 II 1! 11 i; it i < '78 11 II t? 11 II P P P 1-2 rof ile 1.5 1-2 1.5 1 11 1-2 ti rof ile 1-2 rof ile 1-2 It It X X X X X X X X X X X X X X X X X X X X I Nov 09 '77 2 X J Nov 02 '78 1-2 X mac. in Fucus = macrofauna in Fucus metabolism studies quantitative sampling Mytilus edulis 279 me :tab stud. quant samp M . ed ilis BENTHAL INVESTIGATION Station Date epth Samples Samples for Degree of initial (m) cfl oil analyses oil impact o o u u •H -r-l CJ CJ CD c 0) 01 cO CO u cOi a; o o o ■3 CD O -CI 10 c: o 01 "H >H OJ 5; 291 A! :o V) Ms O XJ ■u U o R 0) o 292 293 w H R 0) is :os A! to to o O r M •■H 0 Mh O O, 3 tu o i-H 1 X W V T* ,r 'a R to 4 H • A R «. 1 1 QJ ll ■ in ^W A! to ? :0 .1 to •H 0 4h M O 3: 0) ■;.: -■ j ■H i-H U 'H •U In 03 fe5 c 03 to H R 0) in :m a; to :0 to o 'a 03 0 -Q R 03 ■H O «H O a; : 0 a: o ■u :0 W 'a (h :nj t> o in 0 O a) HJ c M O •c: to ^ •H t> *( : O a: <0 0) -u CD -H c H 295 . ^ 0 Is Q, •■H 1 ^ Q) ■C H 0) £5 s •-H u R c H <4 •H -3