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SYMPOSIUM SERIES FOR UNDERSEA RESEARCH, NO A AS UNDERSEA RESEARCH PROGRAM
VOL. 2, NO. 2, 1987 ~~

Scientific Applications of Current Diving
Technology on the U.S. Continental Shelf

Results of a Symposium Sponsored by the Nationa
Undersea Research Program, University of
Connecticut at Avery Point, Groton, Connecticut,
May 1984

Edited by:

Richard A. Cooper

Andrew N. Shepard

National Undersea Research Program

University of Connecticut at Avery Point

Groton, CT 06340

Washington, DC
August 1987

U.S. DEPARTMENT
OF COMMERCE
National Oceanic and
Atmospheric Administration

SYMPOSIUM SERIES FOR UNDERSEA RESEARCH, NOAA'S UNDERSEA RESEARCH PROGRAM
VOL. 2, NO. 2, 1987

Scientific Applications of Current

Diving Technology on the

U.S. Continental Shelf

U.S. DEPARTMENT OF COMMERCE
Clarence J. Brown, Acting
Secretary of Commerce

National Oceanic and Atmospheric Administration
Anthony J. Calio, Under Secretary

Oceanic and Atmospheric Research
Joseph O. Fletcher, Assistant Administrator
Office of Undersea Research
Elliott Finkle, Director

U.S.Depr, -iter/ Copy

Symposium Series for Undersea Research

The National Oceanic and Atmospheric Administration's (NOAA)
Office of Undersea Research provides manned and unmanned undersea
facilities and other research support for investigations of
aquatic environments in the areas of biological, geological,
chemical, and ecological research. There are currently four
national undersea research programs which operate on grants from
NOAA to various universities. These programs are located at: the
West Indies Laboratory of Fairleigh Dickinson University, the
University of North Carolina at Wilmington, the University of
Connecticut at Avery Point, and the University of Hawaii.

NOAA's Office of Undersea Research provides facilities for
scientists to conduct research supporting NOAA's mission
objectives in the areas of: global oceanic processes, pathways
and fate of materials in the ocean and Great Lakes, coastal
oceanic and estuarine processes, ocean lithosphere and mineral
resources, biological productivity and living resources, and ocean
services.

Since its inception, NOAA also has encouraged and supported
the use of submersibles to perform in-situ underwater observations
and data gathering. Many shallow-water submersible missions have
been supported, including the use of the Johnson Sea-Link,
Nektons Beta and Gamma, Delta, and the Mermaid, as well as deep-
water missions using Alvin, and the Pisces 4, 5, and 6. The goals
of the submersible programs are to support the research
requirements of NOAA's major program elements and its Sea Grant
College System.

This Symposium Series for Undersea Research has been
developed specifically to provide a publishing medium for national
symposia whose contents have addressed topics related to undersea
research activities. Additional information concerning this
series and other activities of NOAA's Office of Undersea Research
may be obtained by contacting:

Director

NOAA's Office of Undersea Research

Mail Stop R/SE2

6010 Executive Boulevard, Room 805

Rockville, MD 20852

Suggested Citation Style (example):

Auster, P. J. 1987. The effect of current speed on the
small scale spatial distribution of fishes. In: R. A.
Cooper and A. N. Shepard (eds.), Science Applications
of Current Diving Technology on the U.S. Continental
Shelf. NOAA Symp. Ser. Undersea Res. 2(2):7-16. NOAA
Undersea Research Program, Rockville, MD.

Table of Contents

Page

CHAPTER I . INTRODUCTION Richard A. Cooper 1

CHAPTER II . FISHERIES 5

The effect of current speed on the small scale spatial
distribution of fishes. Peter J. Auster 7

Pre and post drilling benchmarks and monitoring data

of ocean floor fauna, habitats, and contaminant loads

on Georges Bank and its submarine canyons. Richard

A. Cooper, Andrew N. Shepard, Page Valentine, Joseph

R. Uzmann, Alan Hulbert 17

Studies on tilefish fishery biology, ecology, and

bioerosion on the Middle Atlantic and Southern New

England continental shelf. Churchill B. Grimes,

Ken W. Able, Robert S. Jones, David C. Twichell,

Steven C . Turner 49

Observations of gelatinous zooplankton and measure-
ments of vertical bioluminescence in the Gulf of
Maine and on Georges Bank. Carolyn A. Griswold,
Jon R . Losee 71

Direct observation in plankton ecology.

G. Richard Harbison 85

Biological and technical observations of halibut

longline gear from a submersible. William L. High 93

Long-term observations on the benthic biology and

ecology of an offshore dive site in the Gulf of Maine.

Ken Pecci, Alan W. Hulbert 101

Habitat and behavior of juvenile Pacific rockfish
(Sebastes spp. and Sebastolobus alascanus ) off south-
eastern Alaska. Richard R. Straty 109

CHAPTER III . POLLUTION 125

Levels of heavy metals, petrogenic hydrocarbons, and
polychlorinated biphenyls in selected marine samples
from the New England coast. Kenneth J. Pecci 127

Studies of the water column, sediments, and biota at

the New York Bight acid waste dumpsite and a control

area. William C. Phoel, Robert N. Reid, David J.

Radosh, Peter R. Kube, Steven A. Fromm 141

ill

Biomonitoring of deep ocean outfalls in Hawaii.

Anthony J . Russo 149

Water quality of newly discovered submarine ground

water discharge into a deep coral reef habitat.

George M. Simmons, Jr. , F. Gordon Love 155

CHAPTER IV. SEA FLOOR PROCESSES 165

Submerged evidence of Pleistocene low sea levels

on San Salvador, Bahamas. James L. Carew,

John E. Mylroie 167

The Blake Escarpment--a product of erosional

processes in the deep ocean. William P. Dillon,

Page C. Valentine, Charles K. Paull 177

Biological and geological processes at the shelf

edge investigated with submersibles. John K. Reed,

Charles M. Hoskin 191

Continental slope processes and morphology.

James M. Robb, John C. Hampson, Jr 201

Sediment texture and dynamics of outer shelf and

upper slope depths on the southern flank of

Georges Bank. Page C. Valentine 219

CHAPTER V . OCEAN SERVICES 237

A potential untethered ROV for ocean science.

D . Richard Blidberg 239

The MONITOR National Marine Sanctuary - in

perspective. Edward Miller 247

CHAPTER VI. DEFINITION OF NURP-UCAP SCIENCE PROGRAM 261

NOAA Symp. Ser. for Undersea Res. 2(2), 1987

CHAPTER I. INTRODUCTION

Dr. Richard A. Cooper
Program Director
NOAA's National Undersea Research Program
University of Connecticut at Avery Point

Groton, CT

This volume contains nineteen undersea research and
technology papers that summarize the current status of U.S.
continental shelf research supported by NOAA's Office of Undersea
Research during the late 1970 's and early 1980 's. Principal
investigators gave presentations on these research activities
during a NOAA -University of Connecticut sponsored symposium, May
22-24, 1984 with abstracts published in NOAA's Symposia Series for
Undersea Research, Vol. 2, No.l, 1984. Participants in the 1984
symposium were comprised of scientists (biologists, geologists,
chemists, physical oceanographers and archaeologists), operations
specialists, and program managers from all the regions of the
U.S.

Also included in this volume is a definition of the science
objectives and research themes of NOAA's National Undersea
Research Program, University of Connecticut, as discussed during
the 1984 symposium and subsequently refined through numerous
discussions with our northeast region scientists and coordinators
from New England, southern New England, and the Great Lakes.
These science objectives are to be re-examined in 1988 and re-
defined in the context of major research themes pertaining to each
of the three geographic regions for which the University of
Connecticut's program is responsible.

An overview of the papers presented herein clearly indicates
that NOAA supported underwater research conducted from manned
submersibles, and with SCUBA, is in a transitional phase. During
the 1960 's and early 1970 's "submersible science" was primarily a
qualitatively descriptive activity with participants mainly
concerned with observing and photographically documenting the
ecology of one or several species, animal-substrate relationships,
behavior of fishing and research sampling gear, physical and
biological characteristics of water column fauna, surficial
geology of selected environments, and the relationships of bottom
currents to the sediment-water interface and geological features.
In situ sampling in a replicated fashion and site revisitation was
difficult to achieve, if even attempted, given the relatively
ineffective science support capabilities of manned submersibles
that had been designed and outfitted to address commercial "oil
field" type tasks.

The research papers presented in this volume reflect this
transition from a purely descriptive (qualitative) science to one
that is beginning to quantitatively define, through calibrated
sampling and sensing hardware and replication, the various
phenomena and ecological relationships that currently are the
focus of much of our underwater research attention.

For example, submersible based studies of tilefish
populations, their habitats, and bioerosion by tilefish were
conducted by Grimes et al. in the Middle Atlantic - southern New
England region. Horizontal excavations in clay outcrops in the
walls of submarine canyons, scour depressions under rocks and
boulders and vertical, funnel-shaped burrows in compacted clay
substrata are the primary habitats occupied by tilefish. The
abundance and dimensions of these shelters are defined from
Lydonia, Veatch, and Hudson Canyons. Relatively warm stable
temperatures (9-14°C) and the availability of maleable substrates
for burrowing appear to be the major environmental factors
critical to establishing the burrow and excavation shelters.
Also, the rate and net effect of bioerosion as an active erosional
process on the Continental Shelf and Slope was measured around
the head of Hudson Canyon. Tilefish as large as 30 kg construct
funnel-shaped burrows as much as 5 m in diameter and 2 m deep.
Sidescan-sonar images show that the burrowed area corresponds
closely to an 800 km area of large irregularly spaced hummocks 1-
10 m high. The abundance of tilefish burrows and their clustered
distribution has led Grimes et al. to hypothesize that the
activity of tilefish during the Holocene may have created the
hummocky topography.

Fishing behavior of halibut longline gear and the
effectiveness of various types of bait and hooks were
quantitatively assessed by High using submersibles in coastal
waters of Alaska. Several bait types were tested for durability
on traditional "J" type hooks and newly introduced "circle" type
hooks in addition to defining escape rates as a function of hook
type. Half the halibut were hooked within the first two hours of
soak, and less than 10% of the catch were hooked after six hours
of soak, due to the rapid rate of bait loss. Circle hooks were
far superior to traditional hooks, permitting fewer fish to
escape; they captured 60% more halibut, 130% more rockfish, and
100% more miscellaneous species.

A five-year benchmark (baseline) of species abundance,
community structure, habitat associations and contaminant (heavy
metals, petrogenic hydrocarbons and PCB's) loads (surficial
sediments, scallops, lobsters, jonah crabs and tilefish) was
defined by Cooper et al. at site specific study locations on
Georges Bank and in several of the Georges Bank submarine canyons.
Two years of quantitative data collections prior to drilling for
gas and oil and three years after the onset of drilling have
demonstrated no measureable impacts to the megabenthic fauna or
their habitats, thus, a five-year data base exists against which
to judge future drilling activities on Georges Bank or within
the submarine canyons, which seem likely by the Canadians during
the 1990's.

Simmons and Love, in the process of studying the ecology of
deep water benthic algal mats in the Key Largo Marine Sanctuary
with submersibles made the first detection and water quality
measurements of submarine ground water discharge (SGWD) into a
deep coral reef habitat. The importance of the water quality to
perturbation of deep coral reef habitats and contributions to sea
floor processes is very significant. SGWD was measured in-situ

with seepage meters yielding flow rates of 3 1/hr. and 40 ml/hr.
Oxygen levels ranged from 0.30 to 2.32 mg/1. Numerous pesticide
peakes and heavy metal concentrations 100-10,000 times mean sea
water values were measured. These results suggest a high
potential for perturbation of benthic fauna.

Dillon et al . , using the deep diving submersible
Alvin, conducted three transects along the exposed face of the
Blake Escarpment, east of Florida at depths of 1400 to 4000 m.
Outcrops of horizontal strata known to extend westward beneath the
Blake Plateau were sampled. The vertical limestone cliff at the
northern end of the escarpment is maintained by erosion and
corrosion. To the south, broad slopes of rippled pteropod sand
lie between nearly vertical outcrops. The presence of a Mesozoic
reef is indicated. The escarpment's present configuration
resulted from kilometers of subsidence and kilometers of erosional
retreat.

Valentine, using submersibles on the outer shelf, in
a submarine canyon head, and on the gullied upper slope indicates
that sediment dynamics differ markedly in adjacent areas at the
same water depth (150-600 m) on the southern flanks of Georges
Bank. Strong tidal currents directed north and south dominate
flow up and down the canyon axis to 600 m. In contrast, tidal
currents on the upper slope are weak, and intermittent currents
related to Gulf Stream eddies flow eastward along the slope above
300 m. Major sea-floor processes in the energetic canyon head are
erosion and transport, whereas deposition is more likely in the
same depth interval on the more tranquil upper slope.

The above examples are representative of the transition that
NOAA supported undersea research is currently going through.
Research conducted under the auspices of the University of
Connecticut's Undersea Research Program during 1985 through 1987
is strongly geared towards quantitative, experimental, process
oriented studies that require site revisitation on an annual, if
not seasonal, basis. There will always be a need for purely
descriptive studies, especially in those areas that have received
relatively little attention to date. A blend of descriptive and
experimental process oriented research is the goal of the
Connecticut program.

Special thanks are due the reviewers who contributed valuable
time to these proceedings. We thank Marcia Collie, Staff
Assistant in NOAA's Office of Undersea Research (OUR), for her
expert editorial assistance in the final preparation of this
document. NOAA's OUR provided support for the publication.
Constance Fontaine, Jeanie Klemm, Hannah Goodale, and Sheryl
Windsor patiently typed and edited the numerous drafts. Lastly, we
would like to express our appreciation to the authors for their
patience and cooperation during the extended time required to
complete this document.

Digitized by the Internet Archive

in 2013

http://archive.org/details/scientificapplicOOcoop

CHAPTER II

FISHERIES

NOAA Symp. Ser. for Undersea Res. 2 (2) ,1987 7

THE EFFECT OF CURRENT SPEED ON THE SMALL SCALE SPATIAL

DISTRIBUTION OF FISHES

Peter J. Auster
National Undersea Research Program
The University of Connecticut at Avery Point
Groton, Connecticut 06340

ABSTRACT

Observations during the course of over 600 dives (0.5 to 33 m
depth) by biologist-divers at current dominated sites off southern
New England revealed that changing current velocity is a factor
limiting and shifting the small scale spatial distribution of
certain fish species by size class. Fluctuating current speeds
changed the size class composition of each species that foraged on
surfaces exposed to current or in the water column. Current exposed
areas represent continuously varying refuges for planktonic,
epifaunal and infaunal prey; such refuges are available to size
classes of fish which can maneuver under existing current
conditions. Shifts in distribution continuously changed the search
area for prey, hence predation by particular size classes changed
throughout each tidal stage. Physical and behavioral isolating
mechanisms were discerned that may allow fishes to utilize the same
prey resources while reducing instances of direct competition. I
suggest that cyclic changes in tidal current velocity may act on
fish communities in a manner similar to the way physical disturbance
and predation act on other communities in mediating coexistence.
Disturbance mechanisms may be important mediating factors
contributing to the maintenance of species diversity in temperate
marine fish communities where species exhibit high degrees of prey
overlap at the intraspecific and interspecific level.

INTRODUCTION

Studies of food habits and spatial resource partitioning in
marine fish communities have appeared with greater frequency in the
recent literature (Tyler, 1972; Smith and Tyler, 1972; Hobson and
Chess, 1976; Langton and Bowman, 1980; Hacunda, 1981; and others).
These studies reflect a broader ecological interest of how species
coexist. Resource utilization, such as how prey species are
partitioned by sympatric predatory species, has been studied to
determine community dynamics and develop hypotheses about community
structure in general (Schoener, 1974) .

Langton and Bowman (1980) and Hacunda (1981) found high degrees
of food overlap in studies of fish communities in the northwest
Atlantic. Percent similarity and overlap indices ranged as high as
0.75, indicating significant overlap in prey species utilization by
a variety of predators. For species to coexist and minimize inter
and intraspecific competition, slight differences in the foraging
behavior of predators have been proposed, including feeding on
different sizes of prey, feeding at different times, or in different
areas (Smith and Tyler, 1972; Tyler, 1972; Ross, 1977; Werner,
1977; Jones, 1978; Keast, 1978).

This line of reasoning implies a mechanism would be needed that
isolates one species from another, or one size class from another,
resulting in a reduction of direct competition for specific prey
resources. For example, Smith and Tyler (1972) described space
resource sharing in a coral reef fish assemblage and interpreted the
species specific behavior patterns as a mechanism to reduce competi-
tion.

In this paper, I hypothesize that current velocity constrains
the small scale distribution of temperate marine reef fishes. I
present observational data to support this hypothesis, discuss how
this process might reduce competition for prey resources, and apply
these assumptions to other temperate, demersal fish communities.

The hypothesis states that as current velocity increases or
decreases over the substrate, the small scale distribution of size
classes of different species contracts or expands respectively.
This process changes the size class composition of each species that
can forage in particular places in the water column or on current
exposed surfaces. Shifts in distribution continuously change the
search area, hence predation by particular size classes changes
throughout each tidal stage. This size class isolating mechanism
would allow different fish predators to share the same prey
resources on a small scale and reduce instances of direct
competition.

METHODS AND STUDY AREA

Direct underwater observations were made of common fish species
at temperate rocky reefs in southern New England between 1979 and
1983. Observational data consisted of immediate post-dive
debriefing of species-specific and interactive behaviors and under-
water photodocumentation of selected behavioral phenomena. This
data set from over 600 dives between 0.5 and 33 meters depths has
allowed me to develop a general chronology of activity at these reef
sites. Observations were made at many sites throughout New England,
but primarily at Latimer Reef and Ellis Reef in Fishers Island
Sound, off Wreck Island on the south shore of Fishers Island, and
off Bull Point on Conanicut Island in Narragansett Bay, Rhode
Island. Dives were made at all stages of the tidal cycle.

OBSERVATIONS

Gunner, Tautogolabrus adsperus, typically aggregated at various
heights of rocky reefs in loose foraging groups. Individuals were
often seen preying on planktonic, epibenthic or infaunal species in
a common scan and pick feeding mode (sensu Keenleyside, 1979) .

Observations of cunner aggregations, during various tidal
stages and in areas of significant tidal current velocity (the
velocity which begins to limit maneuverability) , demonstrated
distinct changes in height (see Table 1 and Figure 1 for example)
and distribution by size class of fish above and on the bottom.
Larger fish foraged further from the reef substrate and on current
exposed surfaces for longer periods of time. As current velocity

over the reef decreased, smaller size classes of cunner swam up into
the water column and out onto current exposed surfaces in search of
prey. In some areas, even young of the year individuals foraged in
reef sections previously exposed to currents. As current speeds
increased the process reversed itself.

For example, data from one observation period (Table 2a) show
distinct changes in size class composition over a current exposed
surface during part of a tidal cycle. A two-way analysis of
variance (Table 2b) shows that the interaction of both current speed
and size class of individuals have significant effects on the number
of fish foraging on current exposed surfaces. Figure 2 is a
schematic representation of the situation on a typical reef.

Individuals swimming into the fast current region generally
traveled in the downcurrent direction. Observations at the
downcurrent edge of Ellis Reef indicated that generally no animals
were lost from the reef at high current speeds. Since all size
classes occurred at the upcurrent edge of the reef at high current
speeds, it would seem that movement of the respective size classes
within the reef system is downcurrent above the reef and through the
reef infrastructure, but upcurrent only through the reef
infrastructure (Figure 3) . Individuals were occasionally followed
which demonstrated this complete behavioral sequence.

Feeding was observed during all stages of the tidal cycle.
Even at high current velocities, when no fish were above the reef or
on surfaces exposed to current, individuals were observed within
crevices and in low current areas of the reef continuing their scan
and pick feeding.

Other sympatric reef fish species were also observed to be
current-limited in the extent of their foraging area. Rock eel,
Pholis gunnellus, radiated shanny, Ulvaria subbifurcata, and grubby
sculpin, Myoxocephalus aenaeus, were all limited by size class to
areas of the reefs where they could effectively search for prey.
All three species were limited to low current areas of the reef
during high current periods, with some individuals searching at
current-exposed surfaces or over adjacent sand plains at slower
current speeds.

Semi-demersal migratory schooling species such as scup,
Stenotomus chrysops , and pelagic schooling species such as the
Atlantic silverside, Menidia menidia, have been observed to search
and take prey species through these reef areas during both slow and
fast current speed periods. Scup were observed to feed in a scan
and pick mode on adjacent sand plains around the reefs and rock
surfaces. Atlantic silversides preyed only on planktonic prey
species.

DISCUSSION

Observations at current-dominated rocky reef sites off southern
New England revealed that changing current velocity is a factor
limiting and shifting the spatial distribution of fishes by size
class. For example, as current velocity decreased, a species or
size class group with an overlapping prey preference with a
different species or size class group was able to extend its range
into prey refuge areas which were previously inaccessible due to
high current velocity.

Figure 1. A) An aggregation of cunner at slack current. All size
classes present on the reef are swimming above the reef
infrastructure. B) After the tide has turned (current velocity less
than 0.2 5 kt) many individuals and the smallest size classes have
moved closer to the substrate. C,D, and E on opposite page: C) At
higher current velocities ( in this photograph, approximately 0.75
kt) only the largest size class individuals are able to maneuver in
the current. Note the single large cunner (approximately 140 mm TL)
and how the macroalgae are bent over in the direction of flow. D) A
small cunner (approximately 50 mm TL) sheltered in a crevice from
the current. E) Cunner exhibiting the common scan and pick feeding
mode. Note the individual in the center biting at Tubularia sp.

. i

v;^?r v^j

1. 2.

Table 1. Height above reef of cunner shoal (Latimer Reef
6 August 1983) :

TIME

VISUALLY ESTIMATED
HEIGHT ABOVE REEF

ESTIMATED
CURRENT SPEED

1245
1300
1315
1330

< 1 m

1 m

> 3 m

1.5 kt.
0.75 kt,
0.25 kt,
O

1. - Observations of largest size class present,

2. - Depth approximately 10 m.

Table 2. Size class composition of cunner observed over current

exposed surface at different tidal current speeds (fn. 1) .

(a) Mean number of individuals (and standard deviation) over current
exposed surface (fns. 2,3):

Size Class

Current Velocity
1 kt. 1/2 kt. 0 kt.

Large

Medium

Small

0.33
(0.58)

0.00
(0.00)

3.33
(1.53)

3.67
(1.53)

0.00
(0.00)

7.33
(2.08)

10.33
(2.08)

9.00
(2.65)

Two-way analysis of variance:
Source df SS MS

Size class 2

Current

Speed 2

Interaction 4

Error
Total

18
26

14.52 7.26 3.16 significant at p .10

367.63 183.81 78.89 significant at p .005

23.93 5.98 2.57 significant at p .10

42.00 2.33
448.07

- Observations at Beebe Cove, Groton, Connecticut, on 10
December, 1983. Tidal stage observed was high slack to ebb.

- Data from three 1-minute observation periods per size class
at each current speed stage.

- Size class groupings for individuals was by visual
approximation (i.e., large 60 mm TL; Medium 40-60 mm TL;
small 40 mm TL) .

Current Direction
-»>1 kt

Adult

— 0+ Year Class

Length of horizontal line represents relative size class.

Figure 2. Schematic representation of the distribution of cunner in
relation to current speed on a typical reef.

CD
OC

Current Direction
>

Downcurrent
Movement

Foraging
I

Movement
Upcurrent
Through
Reef
J.

Figure 3 . The general chronology of movement over a reef of cunner
utilizing currents as a transport mechanism in the downcurrent
direction.

By moving, the pool of potential prey and search area increases,
while the density of potential competitors is reduced.

Blaxter (1969) reviewed data regarding endurance speeds and
burst speeds of some commercially important species and showed
significant differences between species and between size classes
within species. Studies by Howard (1980) and Howard and Nunny
(1983) showed that the distribution of lobster, Homarus gammarus , is
limited by tidal current and wave action to low current areas of the
seabed, also on a size selective basis. Differences in current speed
regimes at several coral reef sites have been found to effect the
distribution, abundance and diversity of diurnal and nocturnal
planktivorous fishes (Hobson and Chess, 1978; Thresher, 1983). These
studies are consistent with the observation that current velocity

can restrict the small scale distribution of fishes.

Fish species have developed behavioral mechanisms for coping
with current velocities which impair their ability to maneuver.
Cunner sometimes utilized currents as a means of transport over
reef surfaces, extending their search for prey. Cunners, grubby
sculpins, rock eels and radiated shannys all expanded and contracted
their distribution with changing current velocities and entered
shelter at the appropriate times.

These physical and behavioral isolating mechanisms may allow
predators to utilize the same prey resource while reducing direct
competition. Current dominated areas produce spatial and temporal
prey refuges from specific size classes of fish predators. An
individual's maneuverability in such an area increases the pool of
potential prey and at specific tidal stages reduces the density of
potential direct competitors.

If one were to make predictions from the stated hypothesis,
then some amount of consumptive and encounter competition, as
described by Schoener (1983) , probably occurs during periods of high
current speeds when there is maximum packing of individuals in the
reef infrastructure. Since cunner are the dominant species, have
limited home ranges (Green, 1975; 011a et al. , 1975) and have a
biomass exceeding values for some tropical reef fish communities
(Sand, 1982) , these interactions may be maximized (but not
necessarily extreme) at this point. Food habits data on an
assemblage from a simultaneous sample at this tidal stage might show
a maximum amount of partitioning of prey resources, both between and
within species. Conversely, at periods of lessening tidal current,
dispersion of individuals occurs and competitive interactions
should be reduced. Food habits data from a sample at these stages
should show a decreasing amount of prey resource partitioning owing
to the expanded potential prey pool.

It is difficult to assess the actual amount of prey species
overlap which occurs on a small scale since no high resolution food
habits studies have been conducted for northwest Atlantic coastal
reef fish communities. The previously cited studies of trawlable
demersal assemblages do indicate a significant amount of overlap in
specific species groups and within species on a large scale.
Bigelow and Schroeder (1953) show many common prey taxa for the
principle species discussed which suggests some amount of overlap
would occur. Simultaneous sampling of sympatric species which is
sensitive to spatial and temporal variations is essential in
determining how prey resources are utilized (Chess, 1979) .

The role of disturbance mechanisms in mediating coexistence in
a variety of assemblages has been well documented in the ecological
literature (Dayton, 1971; Weins, 1977; Caswell, 1978; and many
others) . I suggest that cyclic changes in tidal current velocity
may affect fish assemblages in a manner similar to the effects of
predation and physical disturbance on other faunal assemblages.

In the northwest Atlantic, an area with semidiurnal tides,
tidal heights vary from 3 to 4 m in the Gulf of Maine and 1 to 1.5 m
off the southern New England coast. Current velocities vary by area
depending upon the bottom topography. Many areas commonly have
maximum tidal velocities in excess of 1 knot. Therefore, fish
assemblages in this region are subject to varying degrees of
current-induced changes in small scale distribution. Changing

current velocities may be an important mediating factor contributing
to the maintenance of species diversity in temperate marine fish
communities where component species exhibit various degrees of prey
resource overlap at the intraspecif ic and interspecific level.

ACKNOWLEDGEMENTS

I would like to thank C. Lavett Smith, John P. Ebersole,
Stephen T. Tettelbach and Robert E. DeGoursey for reviewing various
drafts of this paper and Joyce Lorensen for expertly typing the
manuscript. The boat crew and staff of The University of
Connecticut, Marine Research Laboratory, provided indispensible ship
and facilities support. This is contribution No. 177 of the Marine
Research Laboratory, The University of Connecticut, Noank, CT.

REFERENCES

Bigelow, H.G. and W. Schroeder. 1953. Fishes of the Gulf of Maine.

U.S. Fish Wild. Serv. Fish. Bull. 74:1-577.
Blaxter, J.H.S. 1969. Swimming speeds of fish. In: Proceedings of

FAO conference on fish behaviour in relation to fishing

techniques and tactics, p. 69-100. FAO Fish. Rep. No. 62,

Vol . 2 .
Caswell, H. 1978. Predator-mediated coexistence: A nonequilibrium

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Chess, J.R. 1979. Some procedures for assessing organisms

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Simenstad (eds.). Fish Food Habit Studies. Proceedings of the

Second Northwest Technical Workshop, p. 25-28. Washington Sea

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organization: the provision and subsequent utilization of space

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a coastal area of the Gulf of Maine. Fish. Bull. 79:775-788.
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Fish. Bull. 74:567-598.
Hobson, E.S. and J.R. Chess. 1978. Trophic relationships among

fishes and plankton in the lagoon at Enewetak Atoll, Marshall

Islands. Fish. Bull. 76:133-153.
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distribution and behaviour of the lobster and edible crab.

Prog. Underwat. Sci. 52:165-169.
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speeds on the distribution and behaviour of the lobster,

Homarus gammarus (L.). J. Exp. Mar. Biol. Ecol. 71:27-42.

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reference to gadoid fish species. Rapp. P. -v. Reun. Cons. int.

Explor. Mer 172:292-300.
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species of an Ontario temperate lake. Environ. Biol. Fish. 3:7-

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behavior. Zoophysiol. Ecol. 11:208 p.
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and comparison of food habits with young tautog, Tautoga

onitis, off Long Island, New York. Fish. Bull. 73:895-900.
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NOAA Symp. Ser. for Undersea Res. 2(2), 1987 17

PRE AND POST DRILLING BENCHMARKS AND MONITORING DATA OF OCEAN
FLOOR FAUNA, HABITATS, AND CONTAMINANT LOADS ON GEORGES BANK AND

ITS SUBMARINE CANYONS

Dr. Richard A. Cooper, Director, National Undersea Research
Program, University of Connecticut, Groton, CT
Mr. Andrew Shepard, Assistant Science Director, National
Undersea Research Program, University of Connecticut, Groton, CT
Dr. Page Valentine, U.S. Geological Survey, Woods Hole, MA
Mr. Joseph R. Uzmann, Chief, Manned Undersea Research and
Fisheries Engineering, National Marine Fisheries
Service, Woods Hole, MA
Dr. Alan Hulbert, Director, National Undersea Research
Program, University of North Carolina, Wilmington, NC

ABSTRACT

Diver scientists from several New England research
institutions (NMFS, NURP, USGS) conducted a before, during and
post-drilling study of the species abundance, community structure,
animal-substrate relationships and body- substrate burdens of
trace metals, PCB's and hydrocarbons within and downstream of oil
and gas exploration areas on the south central portion of Georges
Bank. There was no evidence of impact from drilling on the
megabenthic fauna and the quality of their ocean floor habitats on
Georges Bank and within the Georges Bank Submarine Canyons. The
five (5) year (1980-1984) "benchmark" and monitoring study,
conducted from the research submersible Johnson-Sea-Link, was
supported by NOAA's Office of Undersea Research (OUR) and the
National Marine Fisheries Service, Woods Hole, MA.

INTRODUCTION

From 1971 through 1986 the Manned Undersea Research and
Technology (MURT) Program, NMFS, Woods Hole, MA, and the National
Undersea Research Program, University of Connecticut, Avery Point
(NURP-UCAP) conducted in situ studies of the megabenthic (large,
bottom dwelling) fauna and flora of the inner and outer
continental shelf, and upper slope from Cape Hatteras to eastern
Georges Bank and the Northeast Channel (Figure 1) . These studies
partially focused on (1) species abundance, habitat preference
and behavior of the megabenthic fauna of Georges Bank and the
Georges Bank Submarine Canyons, (2) community structure and (3)
variations in these community and species parameters/
characteristics over a 5 year period (1980-1984) . Various
publications (Cooper and Uzmann, 1971; Uzmann et al., 1978;
Valentine et al., 1980a, b; Cooper and Uzmann, 1980a, b, 1981;
Meyer et al., 1981; Able et al., 1982; Cooper et al., 1982;
Valentine et al., 1984a, b; Shepard et al., 1986; Cooper et al.,
1987) have reported the results of these studies. Included in this
research activity were studies directed towards calibrating and
assessing the effectiveness of conventional research survey and
commercial catch gear (lobster trap, gill nets, "ghost" nets and
traps, otter trawl, clam dredge, camera sled, etc.) and
documenting their impact on the ocean floor and its fauna.

v\j>

v>'

^ ^oc^ ( r

wy»j ^VnTTtinmTrh^v \ ^

9cj\ ^nlgeorges bk. \y \r \

/ /w >

NEW ENGLAND AND MID ATLANTIC BIGHT

CONTINENTAL SHELF

SO 100

NAUTICAL MILES

• Sub dives (dry)

o SCUBA, Surface supplied,
submarine look-out

Figure 1 - Undersea research sites of Manned Undersea Research and
Technology Program and the National Undersea Research Program,
University of Connecticut, for the period 1971 through 1986.

Most of the submersible work took place within the Gulf of
Maine, on Georges Bank and in or around the Georges Bank and
Middle Atlantic Bight submarine canyons (Corsair, Lydonia,
Gilbert, Oceanographer, Hydrographer, Veatch, Atlantis, Block,
Hudson, Baltimore, Washington and Norfolk; Figure 2) .
Approximately 600 manned submersible dives have been made in
support of this combined research effort, utilizing 10 different
dive systems. Several unmanned ROV's (Snoopy, Recon IV, Mini-
Rover Mark I and II, Phantom 300 and Super Phantom) have recently
been applied to this undersea research program.

In response to scheduled (July 1981-September 1982)
exploratory drilling (eight holes) for oil and natural gas on
south-central Georges Bank (Lease Sale Area 42, Figure 2), and
expected exploratory drilling along the continental slope south
and west of Georges Bank (Lease Sale Area 52, Figure 2), we began
a pre-drilling (benchmark) definition and monitoring
investigation to identify impact, or lack of impact, on the living
resources of the ocean floor and their habitats.

Figure 2 - Location of site specific "benchmark" and monitoring
stations revisited annually by the Johnson-Sea-Link II
submersible, 1980 through 1984. Sites of eight exploratory holes
drilled by oil companies from July, 1981 through September, 1982
are identified. Stations 5 and 6, 7 and 8, and 9 were located in
the heads of Lydonia, Oceanographer, and Veatch Canyons,
respectively .

Scientists from the U.S. Geological Survey, Woods Hole, MA.,
participated in this study. Twelve years of experience in
conducting in situ research and deep diving operations on the
continental shelf and slope was utilized in defining the sampling
design and operational procedures.

We began the benchmark and monitoring study in the summer of
1980 as part of NOAA's Northeast Monitoring Program (NEMP) . The
following sections of this article briefly summarize the results
of this five year study with emphasis placed on (1) the biology
and ocean floor habitat types of Georges Bank and its submarine

canyons, (2) benchmarks (species abundance, community
structure, and variations thereof) of megabenthic fauna and their
habitats, (3) benchmarks of body and habitat burdens of potential
contaminants, and (4) the uniqueness and productivity of
submarine canyon heads.

METHODS, RESULTS AND DISCUSSION

Biology and Habitats of Submarine Canyons

Our studies of the Georges Bank submarine canyons show that
these large geological features represent unique ecosystems,
largely because of their highly varied, three dimensional habitats
(Valentine et al., 1980a, b; Cooper et al., 1987). The species
abundance and community structure of the megabenthic fauna are
closely related to the surface geology and sedimentary features of
the canyon walls and axes, which in turn are related to the bottom
gradient and currents. The sedimentary features and surface
geology produce the following five habitat types (Cooper and
Uzmann, 1980b; Cooper et al., 1987), which encompasses the full
range of ocean-floor environments observed.

I Flat, featureless or mildly featured, mud/silt/clay substrate
with less than 5% overlay of gravel;

II Level or gradually sloping mud/silt/clay substrate with more
than a 5% overlay of gravel/rock/cobble;

III Level to steeply sloping (50°) sand/clay substrate with an
overlying boulder field;

IV Gradually (3°) to precipitously (70°) sloping exposed
silt/clay substrate (compacted) with biologically eroded
excavations of various shapes and sizes, which we call a
"Pueblo Village" (Figure 3) ; and

V Featured sand dunes/waves with overlying sand ripples.

We hypothesize that submarine canyons function as refugia for
many bottom-oriented species, where there is little, if any,
impact from active fishing gear (Valentine et al., 1980b). Both
species diversity and abundance are greater in canyons than in
noncanyon areas at comparable depths (Cooper et al., 1987).
Canyons also function as important nursery grounds for a wide
variety of bottom-oriented species such as shrimps, Cancer spp.
crabs, American lobster, white hake, cusk, ocean pout, conger eel,
tilef ish, blackbellied rosef ish, etc. , and provide three-
dimensional shelter, rarely occurring in noncanyon areas of the
outer shelf and slope, for the adults of some 2 0 species. The
highly significant animal-habitat associations observed within the
canyons were considered in designing our site-specific benchmark
and monitoring studies (Cooper and Uzmann, 1980b) , as discussed
below.

^'*^^

Figure 3 - Galatheid crabs, Cancer spp. crabs, cleaner shrimp,
American lobster, blackbellied rosefish, and tilefish, as actually
observed in "Pueblo Village" habitat at 200 m in Veatch Canyon.

Benchmarks of Mecrabenthic Fauna

MURT began defining quantitative and qualitative benchmarks
(pre-drilling) of species abundance, community structure, and
animal-substrate relationships in July 1980, at two stations on
Georges Bank and two stations in Lydonia Canyon (Figure 2)
thought to be potential reservoirs for bottom-carried sediments
and entrained contaminants. Revisitation to these monitoring
sites and estimation of selected species and community
parameters, in 1981 through 1984, provided estimates of parameter
variability from year to year as well as an assessment of impact
from exploratory drilling. Exploratory drilling occurred at eight
locations (Figure 2) on Georges Bank from August 1981 through
September 1982. In July 1981, we established two additional
stations in Oceanographer Canyon and a seventh station in Veatch
Canyon in July 1982. Thus, we have five consecutive years of data
from Georges Bank and Lydonia Canyon, four years of data from
Oceanographer Canyon and three years of data from Veatch Canyon.
For logistical and financial reasons, the month of July
represented the time of the year when each of these study sites
was initially examined and subsequently revisited.

Each study site was marked with a 37 khz pinger (5 year
battery) embedded in a pyramid-shaped cement block. We collected
our benchmark and monitoring data primarily through the use of the
Johnson-Sea-Link I and II submersibles. Dive systems were
chartered from the Harbor Branch Oceanographic Institution with
support from NOAA's Office of Undersea Research (OUR), Rockville,
Maryland, which has supported virtually all of our undersea
research since 1971. Four photographic transects (north, south,
east and west) were conducted at each station with the submersible
cruising 600 yards along the bottom at a fixed altitude (one to
two feet) over the bottom, radiating out from or in toward the
station marker. Using two externally mounted (forward and aft) ,
bulk-loaded cameras with 100 watt-second strobes, we took between
1500 and 2600 color photographs (35 mm, high speed Ektachrome
film), representing between 10,000 and 18,000 m2 of ocean floor,
at each study site. Frequency of camera "firing" was 8 to 12
seconds throughout the entire length of each transect.

At our laboratory, each 100 foot role of film was projected
and magnified (15 x) on a film reader. Judgements were made as to
the accuracy, resolution and proper imaging of each photographic
frame prior to analyzing the frame for species abundance and
community structure data. Improper altitude control of the
submersible over the bottom negated the calibration of the
photographic technique and resulted in the rejection of between 5
and 30% of the photographs taken at a given station. Each
"properly" taken photograph encompassed 7 m2 of the ocean floor.
Maintaining proper photographic procedures over a topographically
rugged bottom was relatively difficult to effect. Occasional
camera malfunctions resulted in additional losses of photographic
documentation. Other benchmark and monitoring data were collected
by (1) making direct observations and recording them on audio
tapes, (2) video recordings on 3/4 inch color tapes and (3)
sampling surface sediments and selected biota (e.g. anemones, sea
scallops and lobsters) in situ using the robotic arm of the
submersible. In addition, trapping, sediment grabs and "hook and
line" techniques were effectively used from the surface vessel
(mother ship to the submersible) to augment the in situ
collections.

We have generated a large inventory of species abundance,
community structure, animal-substrate association and animal-depth
distribution data, all categorized and analyzed as a function of
habitat type and station over a 3 to 5 year period. We have also
collected a considerable data base, through in situ observations
and video documentation, on the behavior and general ecology of
the megabenthic fauna of Georges Bank and its associated submarine
canyons (Cooper and Uzmann, 1980a; Valentine et al., 1980a, b;
Cooper et al., 1987). This report will present a brief summary of
the results of this benchmark and monitoring program. A more
detailed report is currently being prepared with the species
abundance data being subjected to appropriate transformations, and
further statistical analysis.

Following is a list of the megabenthic species most commonly
observed/ photographed at the Georges Bank, Lydonia Canyon,
Oceanographer Canyon, and Veatch Canyon study sites from 198 0
through 1984.

Common Name

Mud anemone
Rock anemone

Sea pens
Starfish

Cancer (Jonah) crab

Portunid crab
Hermit crab

Galatheid crab

Lobster

Sea scallop

Squirrel hake

White hake

Silver hake

Cod

Ocean pout

Sculpin

4-spot flounder

Skate

Conger eel

Goosef ish

Blackbellied rosefish

Tilefish

Cunner

Spiny dogfish shark

Scientific Name

Cerianthus borealis
Bolocera sp.
Tealia sp.
Pennatula aculeata
Astropecten sp.
Asterias vulgaris
Cancer borealis
Cancer irroratus
Bathynectes superba
Pagurus sp.
Catapagurus sp.
Munida sp.
Homarus americanus
Placopecten magellanicus
Urophvcis chuss
Urophvcis tenuis
Merluccius bilinearis
Gadus morhua
Macrozoarces americanus
Myoxocephalus sp.
Paralichthys dentatus
Raia sp.

Conger oceanicus
Lophius americanus
Helicolenus dactylopterus
Lophalatilus

chamaeleonticeps
Tautogolabrus adspersus
Squalus acanthias

Hereafter these species will be referred to by their common
names. Sometimes we could not distinguish between species of
the same genus from the photographs, thus the counts of
more than one species of mud anemones, starfish, cancer crabs and
hermit crabs were combined. It should also be noted that two
species demonstrated either a strong positive attraction (spiny
dogfish shark) or avoidance reaction (cod) to the submersible,
thus, these species were omitted from the analysis. All other
megabenthic fauna demonstrated little, if any, reaction to the
submersible, thus, their abundance estimates are considered
valid.

Annual abundance estimates for selected megabenthic species,
by habitat type, are presented in Appendix Tables 1 through 13 for
stations 2 and 3 (Georges Bank) , 5 and 6 (Lydonia Canyon) , 7 and 8
(Oceanographer Canyon) , and 9 (Veatch Canyon) . Stations 2
through 7, however, are considered to be the most important
locations with regard to potential impacts from drilling
operations and establishing a multi-year benchmark for
future commercial operations on Georges Bank.

Distribution of annual abundance estimates (numbers per
10,000 m2, Hectare) are presented in Figure 4 (stations 2 and 3 -
Habitat type I) , Figure 5 (station 5 -Habitat types I and II

combined; station 6 - Habitat type I) and Figure 6 (station 6 -
Habitat types II and III) . Distributions of abundance estimates
for stations with four years of data or less are not presented.
Ninety percent confidence limits are plotted about the grand mean
abundance values for those species that do not clearly demonstrate
an upward or downward trend in abundance over the time period in
question. For those species that appear to be undergoing a trend
in abundance, a least squares line of best fit has been fitted to
the data (e.g. galatheid crab, station 5; starfish, mud anemone,
and jonah crabs, station 6) in Figures 5 and 6.

Of the 3 0 or more megabenthic species that inhabit Georges
Bank and its canyons to depths of 350 m, 14 are likely candidates
for long-term monitoring as "key indicator" species reflecting
possible impact from drilling activity. The criteria (Cooper and
Uzmann, 1981) for key indicator species designation are: (1)
endemic to study area during summer, (2) specific habitat-type
association, (3) relatively long (4-5 years or more) life span,
(4) relatively high population level, (5) population level not
subject to large fluctuations through year-class input, and (6)
individuals easily counted from photographs. Any species that
meets or approximates five of these criteria have been designated
as key indicator species, such as the mud anemone, rock anemone,
starfish, sea pen, sea scallop, cancer crab, galatheid crab, ocean
pout, conger eel, white hake, squirrel hake, blackbellied
rosefish, tilefish and 4-spot flounder.

Examination of Appendix Tables 1-13 and Figures 4-6 suggests
the following with regard to the identification of "key indicator
species" by habitat type, and in some cases specific monitoring
sites:

1. Rock anemones, ocean pout, conger eels, white hake,
blackbellied rosefish and tilefish probably represent
the best key indicator species for a type III Habitat.

2. Sea scallops, starfish, cancer crabs, and squirrel hake
represent good monitoring species for the Type I
Habitats of Georges Bank, but not for the submarine
canyons .

3. Starfish, cancer crabs, and 4-spot flounder represent
good monitoring species for Habitat Types I and II for
the submarine canyons.

Further examination of the benchmark data on annual
variations in species abundance, specifically for the key
indicator species, suggests that no one species is likely to
reflect anything other than a major impact from production
drilling. We therefore suggest that a "community composition"
approach to defining faunal benchmarks and faunal monitoring be
considered in terms of future oil and gas explorations and
monitoring activities. Furthermore, we suggest that community
composition be examined by Habitat type and location (Georges
Bank, submarine canyon head and walls, etc.). For example, the
megabenthic communities described in this study, defined on the

STATION 2

STATION 3

8,000
6,000
4,000
2,000
40 h

0
800

400

80 p

40 -

80
40
0
80
40

—

•

STARFISH

• J

l l I

•
1

40,000
20,000

HERMIT. CRAB

•jEZSMEK

> SKATE

—

•

JONAH.CRAB

•

I I I

MUD ANEMONE

40 r
20

120 r

0
160 r

80 -

120
60

STARFI9H-

I I

_— hermTITr-aT-

• — .

I I I L

->-

SEA

SCALLOP

•

1 1

^^^SQUIRREL^yAKE^
I I I I '

JONAH CRAB

•

FOUR

• SPOT FLOUNDER

• * •

i i i i

1980 1982 1984 1980

Monitoring Year

1982

1984

Figure 4 - Distribution of annual abundance estimates (numbers per
10,000 m2 , i.e. hectare) of selected megabenthic fauna at stations
2 and 3, habitat Type I, from July 1980 through July 1984.
Siginificant trends in abundance were not identified for any
species; grand mean abundance with 90% confidence limits are
portrayed.

STATION 5 (HAB.I +E )

800

STATION 6 ( HAB. I )

40 p
20 -

80 r
40

BLACK •BELLIED •
ROSEFISH

OCEAN POUT •

— — — — — •
I l L

FOUR SPOT FLOUNDER •

1980

1982

1984

0
40

0
200 r

100 -

SILVER HAKE

FOUR SPOT FLOUNDER

1980

1982

1984

Monitoring Year

Figure 5 - Distribution of annual abundance estimates (numbers per
10,000 m2, i.e. hectare) of selected megabenthic fauna at station
5, habitat Types I and II combined, and station 6, habitat Type I,
from July 1980 through July 1984. Grand mean abundance, with 90%
confidence limits, are portrayed for all species, with the
exception of galatheid crabs (station 5) which demonstrated a
significant downward trend in abundance.

|
1

STATION 6 (HAB.H)

STATION 6 (HAB.m)

1980

1982

1984

1980

1984

Monitoring Year

Figure 6 - Distribution of annual abundance estimates (numbers per
10,000 m2, i.e. hectare) of selected megabenthic fauna at station
6, habitat Types II and III, from July 1980 through July 1984.
Grand mean abundance, with 90% confidence limits, are portrayed
from all species with the exception of starfish and mud anemones
(habitat Type II) , and starfish and Jonah crabs (habitat Type
III) , which all demonstrated significant downward trends in
abundance .

basis of numerical dominance and biomass could be described as
follows:

1. Station 2 - Georges Bank, primarily a starfish, cancer
crab, sea scallop and skate community.

2. Station 3 - Georges Bank, primarily a starfish, sea
scallop, squirrel hake and jonah crab community.

3 . Station 5 - Lydonia Canyon - Habitat Type I and II
(combined) , primarily a starfish, mud anemone, cancer
crab, hermit crab, galatheid crab, tilefish and 4-spot
flounder community.

4 . Station 6 - Lydonia Canyon - Habitat Type I , primarily a
starfish, cancer crab, galatheid crab, hermit crab
and, 4-spot flounder community.

5. Station 6 - Lydonia Canyon - Habitat Type II, primarily
a starfish, cancer crab, galatheid crab, hermit crab,
greeneye, and blackbellied rosefish community.

6. Station 6 - Lydonia Canyon - Habitat Type III, primarily
a starfish, galatheid crab, hermit crab, lobster,
blackbellied rosefish, conger eel, and tilefish
community.

Station 7 - Oceanographer Canyon - Habitat Type I,
primarily a mud anemone, starfish, and cancer crab
community.

Station 7 - Oceanographer Canyon - Habitat Type II,
primarily a mud anemone, rock anemone, starfish, and
cancer crab community.

Station 7 - Oceanographer Canyon - Habitat Type III,
primarily a rock anemone, starfish, cancer crab, white
hake, ocean pout, cunner community.

Station 8 - Oceanographer Canyon - Habitat Type I,

primarily a mud anemone, cancer crab, hermit crab,

shrimp, goosefish, 4-spot flounder, hagfish, and silver
hake community.

11. Station 8 - Oceanographer Canyon - Habitat Type III,
primarily a mud anemone, rock anemone, cancer crab,
portunid crab, hermit crab, starfish, blackbellied
rosefish, silver hake, and white hake community.

12. Station 9 - Veatch Canyon - Habitat Type I, primarily a
sea pen, starfish, cancer crab, hermit crab, galatheid
crab, 4-spot flounder, and blackbellied rosefish
community.

10.

13. Station 9 - Veatch Canyon - Habitat Type III, primarily
a sea pen, starfish, hermit crab, galatheid crab,
greeneye, and blackbellied rosefish community. Based
on extensive in situ observations made of the
megabenthic fauna at this station during the 1970s we
believe the tilefish is also a significant (biomass)
member of this community.

Contaminant Loads in Fauna and Sediments

In order to detect hydrocarbon and/or trace metal
contamination in the surface sediments and tissues of key
indicator species downstream of the exploratory drilling sites,
animal and sediment samples were collected by submersible and from
the surface vessel in July 1980, 1981, 1982 and 1983. Surface
sediments and several (4-2 0) specimens of selected megabenthic
species (Cancer crab and scallop - Georges Bank; Cancer crab,
lobster and tilefish -Lydonia Canyon) were collected: scallops
and sediments were collected in situ with the submersible, crabs
were captured in pots, lobsters were purchased from commercial
fishermen fishing at the study sites, and the tilefish were
readily taken with hook and line by the crew members of the
support vessel, R/V Johnson and submersible Johnson-Sea-Link.

The surficial sediments (2 cm below the sediment-water
interface) were collected for trace metal (Barium, Ba; Cadmium,
Cd; Copper, Cu; Chromium, Cr; Mercury, Hg; Lead, Pb; Zinc, Zn) ,
hydrocarbon (aromatic and aliphatic) , and PCB (several
components) analyses. Scallop (muscle and viscera) , cancer crabs
(hepatopancreas and claw muscle tissue) , lobster (hepatopancreas,
claw/tail, muscle tissue, and eggs), and tilefish (dorsal
musculature tissue) were subjected to the same analyses. Trace
metal and hydrocarbon analyses followed the protocols of the
Cambridge Analytical Associates (Cambridge, MA) .

The levels of PCB's from sediment, cancer crab, tilefish and
lobster samples collected from stations 2, 3, 5 and 6 in 1980 were
below the levels of detection (0.005 ppm) . Additional samples in
later years were not collected for PCB determinations.

The samples (sediment and fauna) collected in 1980 through
1983 for hydrocarbon analyses contained FI hydrocarbons considered
to be of biogenic origin and ranged from N.D. (non detectable) to
TR (trace) to 0.53 ppm (tail and claw meat of lobster - station
6) . The concentrations of petrogenic hydrocarbons (FI and FII)
were all N.D. for all sediment and animal samples for two years
prior to exploratory drilling and for two years after drilling had
commenced in August, 1981.

Concentrations of trace metals analyzed from sediment and
animal samples for 1980 through 1983 are presented in Appendix
Tables 14 (stations 2 and 3) and 15 (stations 5 and 6) . Each
trace metal concentration represents a composite sample. Based on
these trace metal concentrations the following conclusions have
been made:

1. Trace metal concentrations in the surficial sediments at
stations 2, 3, 5 and 6 remained relatively constant prior to
and after drilling commenced. Of particular note are the

Barium levels: Barium, in the form of Barite, comprises a
significant percentage, by weight, of drill muds. These
concentrations are similar for both the Georges Bank and
Lydonia Canyon stations

2 . Cancer crab tissue contained similar levels of trace metals
over a four year period, prior to and after the commencing of
drilling operations. Concentrations found in the Lydonia
Canyon samples were similar to those from Georges Bank.

3 Lobster claw and tail tissues were similar in levels of trace
metals over time. The levels of trace metals from tilefish
tissues were also constant over time and similar between
stations 5 and 6 .

Similar results were obtained by the U.S. Geological Survey
during a three-year study that began in July 1981 to establish the
concentrations of trace metals in sediments prior to drilling on
Georges Bank, and to monitor the changes in concentrations that
could be attributed to petroleum-exploration activities (Bothner
et al., 1983; Bothner et al., 1985). Of the 12 elements analyzed
in bulk (undifferentiated) sediments collected in the vicinity of
drilling rigs on Georges Bank, only barium was found to increase
in concentration after drilling commenced in July, 1981. One of
the U.S.G.S. study sites was adjacent to Block 312 (Mobil),
approximately 2 km northwest of our station No. 3. Bothner et al.
(1985) found, "the maximum barium concentration is within the
range of predrilling concentrations measured in various sediment
types from the regional stations of this program." They
determined that about 25 percent of the barite discharged at Block
312 was present in the sediments within 6 km of the drilling rig,
four weeks after drilling was completed at this location. The
barite discharged during the exploratory phase of drilling
was associated with the fine fraction of sediment and widely
distributed around the bank. Bothner et al. (1985) also found
evidence for Ba transport to Great South Channel , 115 km west of
the drilling area and as far east as 35 km, upstream from the
drilling sites. Relatively small increases in Ba, present in the
fine fraction of the sediment only, were detected 8 and 39 km
downstream (seaward) , in the heads of Lydonia and Oceanographer
Canyons. Our surficial sediment samples were not processed to
separate the fine grained sediments, thus our trace metal
detection procedures are probably less sensitive than those
reported by Bothner et al. For one year after completion of the
well at Block 312 the concentration of barite decreased rapidly,
probably a result of resuspension (up to 25 m above the sea
floor) , and sediment transport of barite-rich material present at
the sediment water interface.

Assessment of Faunal Habitats

Animal-substrate relationships are difficult, if not
impossible, to quantify, therefore, subjective interpretations
have been made concerning the three-dimensional characteristics of

animal shelters (bowl-shaped depressions, excavated tunnels, scour
basins around boulders and mud anemones, boulder fields, silt/clay
flats, etc.)/ based on direct observations and extensive video
documentation. Video documentation has been a powerful tool for
judging the nature of animal-substrate relationsips over the 5-
year period and as a qualitative benchmark. for future
considerations regarding commercial drilling operations. Using
the techniques described above, there has been no apparent change
in animal-substrate relationships at stations 2, 3, 5, 6, 7, 8 and
9 during the course of this study.

CONCLUSIONS

Exploratory drilling operations for gas and oil on the south-
central portion of Georges Bank during 1981 and 1982 had no
measurable impact on the abundance of the megabenthic fauna, their
habitats or contaminant loads on Georges Bank and three (3) of the
Georges Bank Submarine Canyons (Lydonia, Oceanographer and
Veatch) . Consequently, the 3-5 year data base, discussed in this
report, will be considered a benchmark against future commercial
drilling operations conducted on Georges Bank or its adjacent
outer continental shelf and submarine canyon regions.
Significantly, recently released information indicates that
Canadian petroleum companies may begin drilling operations on
eastern Georges Bank in the very near future, upstream from our
benchmark study sites.

ACKNOWLEDGEMENTS

This research was supported by NOAA's Office of Undersea
Research, Rockville, Maryland and the National Marine Fisheries
Service, Woods Hole, Massachusetts. The authors are especially
grateful to the operations crews of the R/V Johnson (now named the
R/V Edwin Link) and submersibles Johnson-Sea-Link I and II. owned
and operated by the Harbor Branch Oceanographic Institution, Fort
Pierce, Florida; the determination, professionalism and ingenuity
of these support and operations personnel contributed greatly to
the success of this program.

LITERATURE CITED

Able, K.W. , C.B. Grimes, R.A. Cooper, and J.R. Uzmann. 1982.
Burrow construction and behavior of the tilefish,
Lopholatilus chamaeleonticeos . in Hudson Submarine Canyon.
Env. Biol. Fish. Vol. 7, No. 1.

Bothner, M.H. , Rendigs, R.R. , Campbell, Esma, Doughten, M.W. ,
Parmenter, CM., Pickering, M.J., Johnson, R.G. , and
Gillison, J.R. 1983. The Georges Bank Monitoring Program:
Analysis of trace metals in botton sediments. U.S.
Geological Survey Circular 915. Final report submitted to
U.S. Department of Interior, Minerals Management Service.
3 6 pp.

Bothner, M.H. , Rendigs, R.R. , Campbell, E.Y., Doughten, M.W. ,
Parmenter, CM., O'Dell, C.H. , Cott, D. ,Lisio, G.P.,
Johnson, R.G., Gillison, J.R., and H. Rait. 1985. The
Georges Bank Monitoring Program: Analysis of trace metals in
bottom sediments during the third year of monitoring. Final
report submitted to the U.S. Minerals Management Service.
99 pp.

Cooper, R.A. , and J.R. Uzmann. 1971. Migrations and growth of
deep-sea lobsters, Homarus americanus. Science 177: 288-
290.

Cooper, R.A. , and J.R. Uzmann. 1980a. Ecology of juvenile and
adult American, Homarus americanus, and European, Homarus
crammarus . lobsters. Chapter 13 in Biology of Lobsters. S.J.
Cobb and B.F. Philips, Eds. Academic Press.

Cooper, R.A. , and J.R. Uzmann. 1980b. NEMP 1980 annual report -
Georges Bank and submarine canyon living resources and
habitat baselines in oil and gas drilling areas. 37 pp.

Cooper, R.A. , and J.R. Uzmann. 1981. NEMP 1981 annual report -
Georges Bank and submarine canyon living resources and
habitat baselines in oil and gas drilling areas. 37 pp.

Cooper, R.A. , J.R. Uzmann, A. Shepard, P. Valentine, R. Cook, and
T. Askew. 1982. Pre-oil drilling baselines of ocean floor
fauna, habitats and contaminants of Georges Bank and
submarine canyons. Paper presented at Georges Bank Technical
Conference on Hydrocarbon Exploration and Development.
Nantucket Island, April 1982. Amer. Soc. Environ. Ed., W.H.
Tiffney and R.F. Hill (eds.), pp. 171-180.

Cooper, R.A. , P.C. Valentine, and J.R. Uzmann. 1987. Georges
Bank submarine canyons. Chapter 10 In: R. Backus (ed.),
Georges Bank. Massachusetts Institute of Technology Press.
29 ms pp., 23 figs. 3 tables. In press.

Meyer, T.L., R.A. Cooper and K.J. Pecci. 1981. The performance
and environmental effects of a hydraulic clam dredge. NOAA
Mar. Fish Rev., 43 (9): 14-22.

Shepard, A.N. , R.B. Theroux, R.A. Cooper and J.R. Uzmann. 1986.
Ecology of Ceriantharia (Coelenterata, Anthozoa) of the
Northwest Atlantic from Cape Hatteras to Nova Scotia. Fish.
Bull. 84(3) : 625-646.

Uzmann, J.R., R.A. Cooper, R. Wigley, W. Rath j en, and R. Theroux.
1978. Synoptic comparison of three sampling techniques for
estimating abundance and distribution of selected
megabenthos: submersible vs. camera sled vs. otter trawl.
NOAA Mar. Fish. Rev. Paper 1273, 39(12): 11-19.

Valentine, P., J.R. Uzmann, and R.A. Cooper. 1980a. Geological
and biological observations in Oceanographer Submarine Canyon
— descriptions of dives aboard the research submersible Alvin
(1967, 1978) and Nekton Gamma (1974). Geological Survey;
1979. Open File Report.

Valentine, P., J.R. Uzmann, and R.A. Cooper. 1980b. Geology and
biology of Oceanographer Submarine Canyon, N.W. Atlantic.
Marine Geology 38:283-312.

Valentine, P.C., R.A. Cooper, and J.R. Uzmann.
sand dunes and sedimentary environments
Canyon. Journal of Sedimentary Petrology,
figs.

1984a. Submarine

in Oceanographer

Vol. 54 (3), 9

Valentine, P.C., J.R. Uzmann, and R.A. Cooper. 1984b. Submarine
topography, surficial geology, and fauna of Oceanographer
Canyon, northern part. U.S. Geological Survey Miscellaneous
Field Studies Map MF 1531, 5 sheets, 38 fig.'s, 2 tables, and
pamphlet.

Appendix Table 1 - Annual abundance estimates for selected megabenthic species at station
2, habitat type I, for the period July, 1980 through July, 1984. Number photographic
frames analyzed = 856, 395, 1052, 643, and 420 for 1980 to 1984, respectively.

Species

Density - Numbers Per 10,000 m2 (Hectare)
(95% Confidence Limits)
1980 1981 1982 1983 1984

Grand Mean
(90% Conf. Limits).

Mud Anemone

45
(25-70)

62
(31-92)

14
(5-22)

58
(35-81)

(0-10)

36
(11-61)

Starfish

7,515

(7265-

7765)

5,139

(4843-

5435)

5,425

(5015-

5829)

6,941

(6679-

7203)

2,565

(2366-

2763)

5519
(3681-7357)

Cancer Crab

41
(31-51)

51
(25-77)

34
(21-47)

76
(51-101)

34
(13-55)

47
(30-64)

Hermit Crab

43
(23-63)

22
(5-39)

8
(2-15)

22
(8-36)

7
(0-16)

20
(6-34)

Sea Scallop

382
(360-404)

264
(202-326)

244
(212-277)

518
"52-584)

221
(168-274)

326
(208-444)

Squirrel Hake

144
(112-175)

Silver Hake

1
(0-4)

4
(0-11)

23
(11-35)

6
(0-26)

Ocean Pout

8
(2-14)

62
(31-92)

1
(0-4)

9
(0-18)

(0-10)

17
(0-41)

4-Spot Flounder

18
(12-24)

4
(0-11)

30
(18-42)

10
(0-33)

Skate

45
(33-57)

29
(9-49)

48
(45-50)

13
(2-24)

7
(0-16)

28
(11-46)

Appendix Table 2 - Annual abundance estimates for selected megabenthic species at station
3, habitat type I, for the period July, 1980 through July, 1984. Number photographic
frames analyzed = 890, 1572, 1398, 225 and 460 for 1980 to 1984, respectively.

Species

Density - Number Per 10,
(95% Confidence Limits)
1980 1981 1982

000 m2 (Hectare)
1983 1984

Grand Mean
(90% Conf. Limits)

Mud Anemone

8
(2-14)

6
(0-18)

Starfish

25,012

(24,577-

25,477)

27,840

(27,441-

28,238)

35,641

(35,022-

36,259)

25,911

(24,626-

27,196)

26,190

(25,152-

27,228)

28119

(23997-

32241)

Cancer Crab

133
(108-158)

91
(73-109)

59
(44-75)

32
(4-60)

62
(34-90)

75
(39-111)

Hermit Crab

13
(6-20)

25
(15-34)

9
(3-15)

6
(0-18)

9
(2-19)

12
(5-19)

Sea Scallop

73
(59-87)

69
(54-85)

41
(28-54)

32
(4-60)

62
(38-86)

55
(38-72)

Squirrel Hake

96
(74-118)

101
(76-126)

67
(50-85)

76
(27-125)

190
(136-244)

106
(59-153)

Silver Hake

24
(14-34)

10
(1-18)

38
(25-51)

6
(0-18)

15
(4-25)

19
(7-31)

Ocean Pout

54
(34-74)

22
(13-31)

7
(2-12)

32
(4-60)

87
(52-123)

40
(10-70)

4 -Spot Flounder

66
(38-94)

40
(28-52)

20
(8-31)

25
(0-50)

16
(2-29)

(14-52)

Skate

28
(20-36)

17
(10-25)

11
(5-18)

76
(34-118)

84
(55-114)

43
(11-75)

Appendix Table 3 - Annual abundance estimates for selected megabenthic species at
station 5, habitat types I and II combined, for the period July 1980 through
July, 1984. Number photographic frames analyzed = 660, 1651, 1511, 975, and 1525 for
1980 to 1984, respectively.

Density - Numbers Per 10,000 m2 (Hectare)
Species (95% Confidence Limits) Grand Mean
1980 1981 1982 1983 1984 (90% Conf. Limits)

Mud Anemone

327 344 347 485 551 411

Starfish (251-404) (293-394) (295-399) (428-542) (496-606) (315-507)

205 40 330 48 73 139

Cancer Crab (145-264) (24-56) (268-392) (31-65) (53-92) (19-259)

4159

5168

1760

1911

3533

3250

(2972-

(3700-

(1394-

(1480-

(3077-

(1644-4855)

5346)

6636

2125

2342

3987)

Hermit Crab

125
(72-178)

1437

(1111-

1763)

1646
(1466-
1826)

699
(574-824)

432
(372-492)

868
(247-14

Galatheid Crab

343
(175-512)

246
(186-305)

357

(274-440)

125
(84-166)

38
(21-55)

222

(90-354

Ocean Pout

14
(0-28)

21
(10-32)

22
(9-34)

9
(2-16)

19
(10-27)

17
(12-22)

Blackbellied
Rosef ish

11
(0-24)

5
(0-11)

7
(0-13)

(0-7)

4
(0-8)

6
(3-9)

Tilefish

9
(0-18)

6
(3-9)

5
(0-10)

6
(1-11)

5
(2-8)

6
(5-8)

36 23 72 32 46 42
4-Spot Flounder (13-60) (11-35) (48-96) (19-45) (32-61) (24-60)

Appendix Table 4 - Annual abundance estimates for selected megabenthic species at

station 6, habitat type I, for the period July 1980 through July, 1984. Number

photographic frames analyzed = 247, 375, 425, 351, and 319 for 1980 to 1984,
respectively.

Density - Numbers Per 10,000 nr (Hectare)

Species

(95% Confidence Limits)

Grand Mean

1980 1981 1982 1983 1984

(90% Conf. Limits)

243

Mud Anemone

...

(67-418)

(3-27)

(0-12)

(0-25)

(0-205)

567

1245

138

126

161

447

Starfish

(437-696)

(1005-
1485)

(89-187)

(82-170)

(96-227)

(0-907)

621

114

135

157

209

Cancer Crab

(398-844)

(74-154)

(89-180)

(2-38)

(66-247)

(0-434)

972

1245

1328

301

779

Galatheid Crab

(850-1093)

(777-1713) (1015-

(187-415)

(21-119)

(232-1325)

1640)

6889

2654

4309

2308

269

3286

Hermit Crab

(5464-

(2178-

(3750-

(1960-

(154-384)

(929-5643)

8314)

3130)

4868)

2656)

142

118

4 -Spot Flounder

(78-206)

(7-54)

(80-155)

(28-86)

(17-99)

(37-126)

128

370

105

Greeneye

(61-195)

(267-472)

(2-32)

...

(0-25)

(0-254)

Blackbellied

Rosef ish

(0-32)

(0-25)

(0-10)

(0-26)

...

(4-16)

Lobster

(0-77)

...

Appendix Table 5 - Annual abundance estimates for selected megabenthic species at
station 6, habitat type II, for the period July, 1980 through July, 1984. Number
photographic frames analyzed = 186, 534, 254, 448, and 448 for 1980 to 1984,
respectively.

Species

Density - Numbers Per 10,
(95% Confidence Limits)
1980 1981 1982

000 m2 (Hectare).
1983 1984 (90%

Grand Mean
Conf. Limits)

Mud Anemone

1828

(1099-

2557)

727
(320-
1133)

343
(210-476)

17
(0-50)

156
(7-255)

614
(0-1308)

Starfish

815
(639-992)

548
(430-666)

276
(206-345)

185
(106-264)

223
(169-277)

409
(154-664)

Cancer Crab

72
(27-126)

35
(16-54)

45
(14-76)

17
(0-40)

108
(54-163)

55
(22-89)

Galatheid Crab

38029

(38841 -

41216)

19236

(17565-

20908)

11755

(10672-

12837)

5681

(5015-

6347)

2765
(2437-
3092)

15,493
(2071-
28,915)

Hermit Crab

242
(116-368)

123
(71-175)

124
(50-197)

92
(34-150)

70
(36-104

130
(67-194)

4 -Spot Flounder

27
(0-57)

51
(18-83)

16
(2-30)

19
(0-39)

Greeneye

959
(596-1322)

560
(374-746)

394
(269-518)

134
(49-219)

3
(0-9)

410
(52-768)

Blackbellied
Rosef ish

117
(51-183)

238
(183-293)

135
(118-152)

445
(310-580)

421
(343-498)

271
(124-419)

Lobster

9
(0-24)

8
(0-17)

8
(0-18)

5
(0-10)

Appendix Table 6 - Annual abundance estimates for selected megabenthic species at
station 6, habitat type III, for the period July, 1980 through July, 1984. Number
photographic frames analyzed = 19, 95, 49, 53, and 101 for 1980 to 1984 respectively.

Density - Numbers Per 10,000 nr (Hectare).
Species (95% Confidence Limits) Grand Mean
1980 1981 1982 1983 1984 (90% Conf. Limits)

Mud Anemone

...

(0-88)

...

1491

872

991

458

311

Starfish

(458-

(587-

(539-

(248-668)

(176-446)

2524)

1157)

1444)

32456

13027

12682

6550

4201

Galatheid Crab

(16794-

(10382-

(11404-

(4836-

(3330-

48118)

15671)

13960)

8264)

5072)

263

Hermit Crab

(0-564)

(3-191)

(0-170)

(0-198)

(0-67)

4 -Spot Flounder

...

6
(0-18)

825
(379-1270)

13783
(3181-24385)

110
(24-195)

Greeneye

Blackbellied

439

Rosef ish

(0-889)

175

Conger Eel

(0-428)

614

Tilefish

(3-1225

601 466 863 863 646
(0-889) (409-794) (184-749) (492-1235) (646-1080) (449-844)

75 204 54 42 110
(9-141) (59-349) (0-128) (0-90) (39-181)

45 79 108 99 189
(0-112) (0-170) (5-211) (17-181) (0-417)

Lobster

263 60 79 54 14 94
(0-564) (2-119) (0-170) (2-106) (0-42) (1-187)

Appendix Table 7 - Annual abundance estimates for selected megabenthic species at
station 7, habitat type I, for the period July, 1981 through July, 1984. Number
photographic frames analyzed = 226, 148, 287, and 24 for 1981 to 1984 respectively.

Density - Numbers Per 10,000 nr (Hectare).

Species

(95% Confidence Limits) Grand Mean

1981 1982 1983 1984 (90% Conf. Limits)

Mud Anemone

145
(78-212)

(12-104)

348
(212-484)

119
(52-290)

168
(20-315)

Rock Anemone

40
(6-74)

1071
(270-1872)

278
(0-900)

Starfish

25
(1-50)

222
(0-497)

622
(406-838)

893
(464-1322)

441
(0-900)

Cancer Crab

405
(264-545)

425
(270-579)

244
(156-332)

238
(53-529)

328
(209-447)

Galatheid Crab

1024
(703-1345)

39
(0-85)

266
(0-861)

Hermit Crab

32
(4-59)

10
(0-29)

20
(1-39)

25
(3-47)

22
(11-33)

Sea Scallop

13
(0-30)

(0-11)

4 -Spot Flounder

19
(0-40)

10
(0-29)

7
(0-18)

Greeneye

13
(0-30)

48
(6-90)

10
(0-30)

24
(2-46)

24
(3-44)

Blackbellied
Rosef ish

White Hake

Ocean Pout

6
(0-19)

25
(3-47)

8
(0-22)

Cunner

Appendix Table 8 - Annual abundance estimates for selected megabenthic species at
station 7, habitat type II, for the period July, 1981 through July, 1984. Number
photographic frames analyzed = 397, 357, 191, and 198 for 1981 to 1984 respectively.

Species

Density - Numbers Per 10
(95% Confidence L
1981 1982

,000 m2 (Hectare)
imits)

1983 1984

Grand Mean
(90% Conf. Limits)

Mud Anemone

489
(378-601)

300
(212-389)

1055
(706-1404)

43
(4-83)

477
(0-979)

Rock Anemone

702
(487-917)

156
(91-221)

411
(255-567)

1061
(537-1584)

583

(125-1040)

Starfish

698
(579-825)

756
(623-889)

711
(544-878)

758
(589-926)

731
(695-767)

Cancer Crab

169
(119-219)

76
(41-111)

157
(93-221)

115
(61-170)

129
(79-179)

Hermit Crab

11
(0-23)

16
(0-32)

7
(0-22)

29
(1-57)

16
(4-27)

Galatheid Crab

4668
(3820-5517)

536
(481-592)

1301
(0-3959)

Sea Scallop

7
(0-17)

7
(0-21)

4
(0-8)

4-Spot Flounder

4
(0-12)

14
(0-34

5
(0-12)

Greeneye

14
(0-32)

7
(0-22)

5
(0-13)

Blackbellied
Rosef ish

47
(22-72)

16
(0-32)

16
(0-42)

White Hake

4
(0-12)

105
(38-172)

58
(18-97)

42
(0-100)

Ocean Pout

7
(0-17)

4
(0-12)

319
(274-364)

159
(90-228)

122
(0-298)

Cunner

Appendix Table 9 - Annual abundance estimates for selected megabenthic species at
station 7, habitat type III, for the period July, 1981 through July, 1984. Number
photographic frames analyzed = 316, 325, 333, and 318 for 1981 to 1984 respectively.

Density - Numbers Per 10,000 nr (Hectare)

Species

(95% Confidence Limits)

Grand Mean

1981 1982 1983 1984

(90% Conf. Limits)

Mud Anemone

(0-46)

4295

Rock Anemone

(3585-

5005)

696

Starfish

(564-829)

448

Cancer Crab

(364-549)

Galatheid Crab

...

Hermit Crab

...

Sea Scallop

...

4 -Spot Flounder

...

44 30 5 26

(14-74) (5-55) (0-13) (6-45)

2435 3822 1851 3101

(1961- (3094- (1400- (1751-4451)

2909) 4550) 2302)

1116 390 921 781

(956-1277) (288-492) (786-1056) (414-1148)

185 223 193 262

(122-247) (147-299) (134-252) (115-409)

92 34 9 34

(20-164) (0-346) (0-21) (0-82)

0 17 5 6

(0-34) (0-13) (0-15)

Greeneye

(0-21)

2
(0-8)

Blackbellied 50 26 21 18
Rosefish (21-79) (5-47) (2-40) (0-35)

29
(12-46)

White Hake

258 272 292 984 452

(177-338) (168-376) (219-365) (780-1187) (36-869)

Ocean Pout

646 400 1866 3086 1500

(521-772) (300-500) (1622- (2735-3437) (44-2956)

2110)

Cunner

68 35 52 38
(16-21) (11-59) (17-87) (15-61)

48
(30-66)

Appendix Table 10 - Annual abundance estimates for selected megabenthic species at
station 8, habitat type I, for period July, 1981 through July 1984. Number photo-
graphic frames analyzed = 1438, 663, 388, and 623 for 1981 to 1984 respectively.

Species

Density - Numbers Per 10,000 nr (Hectare)

(95% Confidence Limits) Grand Mean
1981 1982 1983 1984 (90% Conf. Limits)

Mud Anemone

73
(54-92)

185
(71-300)

15
(0-30)

21
(0-98)

74
(0-166)

Rock Anemone

7
(0-14)

(0-6)

Cancer Crab

315
(279-351)

347
(285-409)

596
(514-678)

757
(297-1216)

504
(256-751)

Lobster

2
(0-6)

1
(0-2)

Shrimp

2512
(2157-2866)

2659
(2281-3037)

784
(472-1096)

1489
(0-3027)

Portunid Crab

12
(5-19)

26
(9-43)

7
(0-15)

14
(0-71)

15
(5-24)

Hermit Crab

1951
(1726-2176)

4570
(4129-5011)

390
(298-482)

294
(0-599)

1801
(0-4150)

Starfish

10
(1-20)

24
(10-38)

44
(21-67)

(18-48)

28
(11-45)

Skate

4
(0-8)

9
(0-17)

7
(0-15)

7
(0-47)

7
(4-9)

Goosefish

10
(1-20)

30
(13-47)

41
(21-61)

5
(0-38)

22
(2-41)

4-Spot Flounder

7
(2-12)

30
(13-47)

59
(31-87)

76
(0-211)

43
(7-79)

Greeneye

71
(42-99)

11
(1-20)

7
(0-15)

22
(0-61)

Blackbellied
Rosef ish

8
(2-14)

(0-6)

7
(0-15)

2
(0-26)

5
(1-9)

Hagfish

112
(74-151)

82
(51-113)

96
(58-134)

16
(0-78)

77
(27-126)

Silver Hake

156
(119-193)

(0-11)

99
(64-134)

2
(0-26)

70
(0-153)

White Hake

4
(0-8)

4
(0-11)

37
(0-145)

11
(0-32)

Appendix Table 11 - Annual abundance estimates for selected megabenthic species at
station 8, habitat type III, for the period July, 1981 through July, 1984. Number
photographic frames analyzed = 112, 663, 120, and 318 for 1981 to 1984 respectively.

Density - Numbers Per 10,000 nr (Hectare)

Species

(95%) Confidence Limits)

Grand Mean

1981 1982 1983 1984

90% Conf. Limits)

Mud Anemone

459
(298-621)

179
(79-278)

536
(374-698)

23
(3-56)

299
(17-581)

Rock Anemone

38
(0-95)

336

(200-472)

202
(126-278)

245
(160-330)

205
(59-352)

Cancer Crab

587
(395-778)

305
(193-417)

429
(300-558)

2830
(2578-3088)

1038
(0-2450)

Lobster

26
(0-61)

9
(0-21)

9
(0-23)

Shrimp

64
(15-113)

137
(39-234)

12
(0-31)

(0-127)

Portunid Crab

42
(1-83)

36
(2-70)

54
(22-86)

(6-60)

Hermit Crab

295
(79-511)

179
(52-305)

119
(54-184)

31
(8-55)

156
(26-286)

Starfish

64
(8-119)

221
(123-318)

298
(194-402)

18
(0-35)

150
(0-305)

Skate

13
(0-38)

10
(0-22)

12
(0-31)

9
(2-16)

Goose fish

26
(0-61)

48
(9-87)

19
(0-46)

4 -Spot Flounder

11
(0-31)

24
(0-52)

23
(3-56)

15
(1-28)

Greeneye

Blackbellied

131

Rosef ish

(0-61)

(0-67)

(69-193)

(6-47)

(0-114)

Hagfish

...

(0-50)

(0-31)

(0-29)

(1-22)

Silver Hake

561

187

(399-723)

(13-113)

(24-118)

(15-93)

(0-481)

White Hake

(0-122)

(0-31)

(3-113)

(4-62)

Appendix Table 12 - Annual abundance estimates for selected megabenthic species at
station 9, habitat type I, for the period July 1982, through July 1984. Number
photographic frames analyzed = 695, 755, and 695 for 1982 to 1984 respectively.

Density - Numbers per 10,000 nr (Hectare)

Species

(95% Confidence Limits)

Grand Mean

1982 1983 1984

(90% Conf. Limits)

Mud Anemone

Sea Pens

4201

3527

3355

(3853-4550)

(3063-3991)

(3005-3705

Cancer Crab

197

263

(157-237)

(219-307)

(25-115)

3694
(2941-4448)

177
(11-342)

Lobster

Shrimp

6 208 0
(0-18) (134-282)

71
(0-271)

Hermit Crab 1484 747 904

(1358-1610) (653-841) (754-1154)

1045
(391-1699)

Galatheid Crab 84 255 29
(42-127) (196-1114) (4-54)

123
(0-321)

Scallop

Starfish

41
(23-59)

655
(527-783)

(4-66)

4 -Spot Flounder

60
(38-82)

51
(35-67)

12
(0-35)

Goosefish

6
(0-13)

38
(24-52)

Greeneye

4
(0-12)

106
(75-137)

72
(2-142)

Blackbellied
Rosef ish

14
(4-25)

40
(23-57)

41
(21-61)

Silver Hake

12
(3-22)

19
(9-29)

10
(0-28)

Skate

(0-11)

244
(0-844)

41
(0-84)

15
(0-49)

61
(0-148)

32
(6-57)

14
(6-22)

1
(0-3)

Appendix Table 13 - Annual abundance estimates for selected megabenthic species at
station 9, habitat type III, for the period July, 1982 through July, 1984. Number
photographic frames analyzed = 0, 45, and 259 for 1982 to 1984 respectively.

Density - Numbers per 10,000 nr (Hectare)

Species

(95% Confidence Limits)

Grand Mean

1982 1983 1984

(90% Conf. Limits)

Mud Anemone

Sea Pens

1397 629
(690-2104) (579-679)

1013
(0-3438)

Cancer Crab

95 6

(7-183) (0-18)

51
(0-331)

Lobster

635
(562-708)

6
(0-18)

321
(0-2306)

Shrimp

Hermit Crab

Galatheid Crab

Starfish

Greeneye

159

(25-293)

(0-47)

4444

287

(3441-5447)

(187-397)

190

(0-503)

(0-59)

286

(43-529)

(0-196)

91
(0-523)

2366
(0-15489)

109
(0-620)

176
(0-871)

Blackbellied
Rosef ish

857

794

(583-1131) (534-1054)

826
(816-835)

Conger Eel

(0-84)

6
(0-18)

19
(0-46)

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NOAA Symp. Ser. for Undersea Res. 2(2), 1987 49

STUDIES ON TILEFISH FISHERY BIOLOGY,
ECOLOGY AND BIOEROSION ON THE MIDDLE ATLANTIC
AND SOUTHERN NEW ENGLAND CONTINENTAL SHELF

Churchill B. Grimes
National Marine Fisheries Service, Panama City, FL 32407

Ken W. Able

Department of Zoology, Rutgers University

New Brunswick, NJ 08903

Robert S . Jones

Marine Sciences Institute, University of Texas

Port Aransas, TX 78373

David C. Twichell

United States Geological Survey, Woods Hole, MA 02543

Steven C. Turner
National Marine Fisheries Service, Miami, FL 33149

ABSTRACT

Manned submersibles were used in the vicinity of submarine
canyons of southern New England and the mid-Atlantic Bight during
the summers of 1979 through 1984 to evaluate the performance of
commercial bottom longline gear, document the abundance and
distribution of tilefish shelters and define the ocean floor fauna
associated with the tilefish shelters. Time-lapse photography
documented tilefish behavior relative to the shelters. Coordinated
submersible, sidescan sonar and seismic profiling operations were
conducted to define the role of bioerosion by tilefish in shaping
seafloor topography. Sidescan sonographs showed individual tilefish
burrows whose distribution were highly contagious. At Hudson Canyon,
tilefish had created an 800 km2 area of rough topography through
bioerosion which has probably been occurring over the past 12-13,000
years.

INTRODUCTION

Because of the major ecological and economic significance of
tilefish, we have studied them since 1979 using manned submersibles.
Our studies have provided information relevant to the rational
exploitation of their valuable fisheries, and discovered their im-
portant role in sea floor processes. In this paper we summarize the
results of these in situ studies; for further details refer to the
original papers on commercial fishing gear performance (Grimes et
al. 1982) ; behavior, community structure and habitat (Able et al.
1983; Grimes et al. 1986); the role of tilefish bioerosion in
shaping bottom topography (Twichell et al . 1985); and use of side-
scan sonar as a fishery tool (Able et al. in prep.).

Tilefish, Lopholatilus chamaeleonticeps , are large (to 120 cm
and 27 kg) demersal branchiostegid fishes found along the edge of
the continental shelf in 80-540 m depths from Nova Scotia to Surinam
(Dooley 1978; Markle et al. 1980). In the Middle Atlantic Bight
and Southern New England waters they have usually been found from
80-240 m. This species is long lived and slow growing, reaching at

least 112 cm FL and 35 years (Turner et al. 1983) . Batch spawning
occurs during summer, with females producing pelagic eggs;
reproduction is socially mediated (Grimes et al. in prep.).
Tilefish are benthic carnivores, the diet consisting mostly of
crustaceans and fishes and secondarily of polychaetes and
echinoderms (Turner and Freeman in prep.). In addition, the
investigations we summarize here suggest that tilefish are
"keystone" species, critical to the organization and maintenance of
their community.

Commercial exploitation of the Middle Atlantic-Southern New
England tilefish stock (Katz et al. 1983) began in 1915, and
landings have been reported nearly every year since. Annual
landings have fluctuated between a peak of 4,500 metric tons (t) in
1916 to 1 t for several years since. Landings have increased
dramatically since the 1970 's, due to the development of an
important longline fishery centered in New York and New Jersey.
Landings from 1977-1982 (2,000, 3,400, 3,800, 3,600, 3,200 and 1,900
t, respectively) exceeded all previous years for which information
is available except 1916 (Freeman and Turner 1977; U.S. Dept. Comm.
1980 a-c; Christensen pers. comm.). Tilefish have been the most
valuable finfish fishery in New Jersey and New York in most years
since 1978.

METHODS AND PROCEDURES

Study sites and submersibles used

We conducted a series of submersible cruises along the east
coast of the U.S. (Fig. 1) during the summers of 1979-1984 (Table
1) . In 1979 we used the two man submersible Nekton Gamma , a 4.9 m
long vessel that could operate to a depth of 300 m. Support for
Nekton Gamma was provided by the R/V Atlantic Twin. All other dives
reported here were conducted with the Harbor Branch Oceanographic
Institution's four-man submersible Johnson-Sea-Link, operated from
the support ship R/V Johnson.

Habitat, behavior and community structure

Dives were made along straight line transects (across or along
depth contours) , or in accordion shaped tracks for more detailed
mapping (see Grimes et al. 1986). On other dives, when specific
tasks (behavior observations, burrow measurement and dissection,
etc.) were planned, the submersible moved very little. During a
typical dive, physical (bottom temperature, depth, topography, visi-
bility, current speed and direction and substrate type) and biologi-
cal (tilefish abundance, size, sex, behavior, burrow number and
dimensions, and associated fish and macroinvertebrates) parameters
were recorded on audio tapes. Photographs were taken with one or
two externally mounted 35 mm cameras and a bow-mounted video camera
with the recorder located in the submersible.

Estimates of tilefish length, habitat dimensions and densities
of associated fish and macroinvertebrates were made from 3 5 mm
photographs projected onto grids of known dimensions. The grids were

rolina

ydonia Canyon

h Canyon
s Canyon

0 100 200 300 400 STATUE MILES
i i i 1 1

0 50 100 150 KILOMETERS

0 50 100 150 NAUTICAL MILES

Figure 1. Map of U.S. east coast showing study sites

Table 1. Summary of submersible operations for tilefish studies along the east coast
of the U.S. during 1979-84. See Figure 1 for locations. Major locations include
Lydonia (LC), Veatch (VC) and Hudson (HC) Canyons. Habitat types indicated as vertical
burrow (VB), Pueblo habitat (PH), boulder field (BF) or other (OH).

1979

1980

1981

1982

Locations

Hudson
Canyon

Lydonia , Veatch
Hudson Canyons

Lydonia, Veatch
Hudson Canyons

Hudson
Canyon

Cruise dates

23-27
August

6-18
August

23-28
July

22-30
July

Number of
dives

Depth range of
observations

85-299 m

LC =
VC =
HC =

139-192 m
117-229 m
146-156 m

LC = 134-268 m
VC = 122-213 m
HC = 144-241

129-227 m

Types of
habitats
observed

LC =
VC =
HC =

VB, PH, BF
VB, PV, BF
VB

same as 1980

1983

1984

Locations

Hudson

Baltimore

Norfolk

Middle Atlantis

Veatch

Canyon

Grounds Canyon

Canyon

Cruise dates

15
Au

-16
gust

17
August

18
August

July- 3 August

4 August

Number of

dives 4

Depth range of

observations 119-175 m 204-253 m 175-247 m

102-243 m 183-337 m

130-132 m

Types of
habitats
observed

originally photographed with the submersible ashore. Estimates for
the above measurements were then corrected to reflect the
differences in light transmission from air to water,
estimates were validated with in situ measurements of objects
Johnson-Sea-Link using rods and weighted lines marked in

checked against photographic estimates of the

increments and

objects. Density estimates for tilefish" and burrow abundance

These
from

known
same
were

determined using the numbers of fish and habitats seen, the length

of the submersible transects and the width observed along the tracks
(based on visibility estimates by the submersible pilot and the
observer) . Interpretation and description of habitat types,
tilef ish behavior, etc. , were aided by reviewing video tapes made
during the dives.

We collected small organisms and made additional observations
using equipment unique to Johnson-Sea-Link. Fishes and
macroinvertebrates associated with tilefish habitat were collected
by injecting rotenone directly into burrows. Fishes and macro-
invertebrates were sucked into a collecting box through a nozzle
attached to the end of the manipulator arm. Tilefish burrows were
dissected with the jaws of the manipulator arm or by blowing
sediments away with the submersible bow thruster.

A 35 mm camera and strobe, controlled by an intervalometer, was
mounted on a tripod and used to take time-lapse photographs of
tilefish and their burrows near Hudson Canyon. Photographs were
taken every 2.0 minutes over a 24 hour period.

Fishing Gear Performance

This study was conducted near Hudson Submarine Canyon (Fig. 1)
in cooperation with the commercial longline vessel Lori-L from
Barnegat Light, N.J. While longlines were being set, hooks were
marked with a series of colored ribbons and numbered plastic tags.
This made it possible to coordinate our in situ observations with
those made by colleagues and the Lori-L crew as the gear was
retrieved. The longline was observed using Nekton Gamma . To
determine the importance of bait predation we calculated the
percentage of hooks observed with predators and without baits at
successive time intervals (High 1980). See Grimes et al. (1982) for
additional details of this procedure.

Sea Floor Processes

In 1982, 1983 and 1984 we investigated the role of sea floor
bioerosion by tilefish in the formation of an area of rough
topography around Hudson Canyon. We employed coordinated
submersible, sidescan sonar and subbottom profiling operations.
Sidescan sonar images (sonographs) , 3.5 kHz subbottom profiles and
echo sounding profiles were collected from R/V Johnson between
dives. The Johnson-Sea-Link was used to "ground truth" features
observed on sonographs and to collect sediment samples for grain
size analysis. In selected areas we constructed detailed maps of
the bathymetry and burrow distribution using closely spaced
echo sounding profiles, sidescan sonographs, and many submersible
dives.

The extent of rough sea floor topography mapped with seismic
profiles was compared to the spatial distribution of commercial
fishing for tilefish. Data on the commercial fishery for tilefish
was obtained through cooperation with commercial longline fisherman
from Barnegat Light, N.J. and Montauk, N.Y. during a study of the
biological basis of management of the fishery (Grimes et al. 1980;
Turner et al. 198 3) . Cooperating fishermen maintained logs
providing necessary catch information (e.g., catch location and
date, and amount of gear fished) . We used these data to produce a
point distribution map of fishing locations (Robertson 1967; Cesney
1972) for comparison to the geological data.

RESULTS AND DISCUSSION

Performance of Commercial Fishing Gear

We made two daytime dives in August 1979 to observe baited
longlines (Grimes et al. 1982) and saw 42 hooked fish; most were
alive and in good condition. Only four tilefish were dead; two had
swallowed the bait and were hooked internally and two fish were
bitten off just behind the operculum, presumably by sharks (probably
the dusky shark, Carcharhinus obscurus) .

The burrowing behavior of tilefish may have caused loss of
catch. Seven (17%) of the 42 tilefish observed on marked longlines
on the bottom were not accounted for on the Lori-L. It is likely
that hooks were pulled free from fish partially in their burrows,
because we observed several attempts by hooked fish to enter
burrows .

Apparently baited longlines attracted tilefish from a wider
area than just the immediate vicinity of the longline. During five
dives made on tilefish grounds (but not along baited longlines) to
investigate behavior and ecology there was a strong positive
correlation (r = 0.91) between the number of tilefish seen and the
number of burrows encountered; few tilefish were away from burrows
(see Fig. 1 in Grimes et al. 1982) . Along a baited longline we
observed many more hooked tilefish (42) than would have been
predicted from the number of burrows sighted (3) , which suggested
that tilefish foraged some distance away from their burrows to take
a baited hook.

Benthic invertebrate predators on bait were an important factor
affecting catch and optimum soak time. Starfish (Astropecten sp.)
accounted for 70% of bait predators observed; the crabs Cancer sp.
and Acanthocarpus alexandri accounted for 26% and 6%, respectively.
Predation began soon after the longline was set and increased
linearly with soak time until all hooks observed were preyed upon
after 190 minutes (Fig. 2) . Complete removal of bait took longer;
all hooks had bait at 78 minutes, but the percent of hooks with bait
began to decrease, falling to 70% (excluding hooks with tilefish)
after 190 minutes. After 8 hours all hooks were bare (Fig. 2) .

We could not determine optimum soak time very precisely. No
fish were caught during the first 60 minutes of the longline set, so
the minimum soak time may be around 2 hours. When 42 tilefish were
caught, all baits were gone after 8 hours (and 90% gone after 7
hours) , which gives the maximum useful time.

Most of this assessment would not have been possible without
the submersible. Information on burrowing behavior and the
resulting catch loss, foraging behavior and its relevance to the
area fished by longlines, and the identification of bait predators
and the predation rate could only have been acquired by traversing a
baited longline with a submersible. The presumed rate of bait
loss from predation (because bait predators could not be directly
observed) and the rate of catch loss from predation could have been
determined from a commercial fishing vessel, the former only with
repeated longline settings and retrievals at time intervals.
Repeated longline settings would have required chartering the vessel
because normal fishing operations would have been precluded. We

believe these factors made the submersible a particularly effective
and efficient sampling platform.

o
o

h-
z
11)
o
or

LU
0-

100

•43

44 44

••

—

•10

—

o40
o40

o42

I I

•

62 „rt
# .7°

I 79,

Wj
DC

O
t-
<

Q
LU
Lt
Cl

LU
H

Lt
LU
Cl

60 120 180 240 300 360

TIME AFTER LONGLINE SET (MINUTES)

420

480

Figure 2. Predation on baited longline hooks by benthic
invertebrates and rate of bait loss. Numbers of hooks observed
between successive time intervals are shown above data points
(from Grimes et al. 1982) .

Sidescan Sonar As a Fishery Tool

Using sidescan sonar in conjunction with submersible operations
we determined that it was possible to identify individual tilefish
burrows on sidescan sonographs (see subsequent Sea Floor Processes
section) . This finding suggested to us that high resolution
sidescan sonar (100 kHz) might have more general utility as a
fishery tool. Because individual burrows were identified it could
be used to find new tilefish grounds, and determine abundance in
unfished areas. It may also be possible to identify critical
habitats of other fishery resources as well, for example boulder and
Pueblo habitats and rock outcroppings, etc. We conducted further

studies in 1984 to establish if some of these other habitats were
identifiable with sidescan sonar, and also determined that the lower
size limit of burrows that could be resolved on relatively flat
bottom was about 0.5 m diameter (Able et al. in prep.).

Habitat, Behavior and Community Structure

Observations from submersibles have shown that tilefish are
shelter seeking fishes that occupy a variety of habitats (Warme et
al. 1977; Uzmann et al. 1978; Valentine et al. 1980; Cooper and
Uzmann 1980; Able et al. 1982; Cooper et al. in press). We cur-
rently recognize three more or less distinct types along the
northeast coast of the U.S.: rocks and boulders, Pueblo habitats and
vertical burrows (Grimes et al. 1986) . These habitats have certain
characteristics in common. They were all found within the "warm
belt" (Verrill 1882) , a narrow zone of relatively warm 9-14° C water
which represents the interface between distinct continental slope
and continental shelf water masses (Christ and Chamberlain 1976) .
Temperature and salinity data obtained during our dives were in
agreement (Grimes et al. 1986). In addition, the presence of ex-
posed clay that provided a malleable substrate for burrowing was
critical to burrow construction and distribution (Able et al. 1983;
Twichell et al. 1985). However, the occurrence and utilization of
the different habitats varied with geological setting, latitude
and season. Fish behavior, residency, and community interactions
and structure differed both between and among habitat types.

Boulders and Rocks

The association of tilefish with large boulders was the
simplest type of tilefish habitat observed. The boulders, either
singly or in clumps, were observed on the rims and along the walls
of submarine canyons. The boulders were variable in size and shape
and ranged from 0.3 - 5 m in diameter. As described by Valentine et
al. (1980) boulders were often in shallow scour basins, probably of
combined physical and biological origin.

Tilefish have been observed utilizing this habitat in depths
from 149-242 m in Veatch, Lydonia, Hudson and Baltimore Canyons
(Able et al. 1982; Grimes et al. 1986) and in Oceanographer Canyon
(Valentine et al. 1980) . This habitat for tilefish appears to be
more common in the northern canyons which were closer to the late
Pleistocene glaciers, the source of these boulders (Valentine et al.
1980; Cooper et al. In press).

Tilefish evidently use boulders for shelter. Typically,
tilefish rested motionless against or, if possible, under a portion
of a boulder. In most instances a single adult tilefish was
observed at a boulder, but on occasion as many as three could be
seen simultaneously. Utilization of boulder habitats appears to be
random and temporary. On several occasions we chased tilefish away
from boulders with the submersible and followed them to note their
subsequent choice of habitats. Fish stopped at various other
boulders and showed no inclination to return to to the original
boulder. Furthermore, on later dives to the same boulder we could
not establish that the same fish was present.

We observed four tilefish occupying excavations under rock
slabs among anemone fields at a dive site along the southwest wall
of Baltimore Canyon. Numerous rock slabs about 1 x 2 m, with their

axes at varying angles to the slope, covered the bottom for a
distance of over 150 m on a steeply sloping (30° ) canyon wall from
2 04 to 2 53 m depth. Excavations in the grey sediment under and
adjacent to rock slabs were common and appeared to be of biological
origin. Fish appeared to orient to a particular habitat; they would
not leave their habitat when prodded with the manipulator arm of the
submarine, as they did at boulder habitats.

Certain crustaceans and other fishes were commonly
associated with rock and boulder habitats (Table 2) . Most of
these associates were ubiquitous with tilefish in these habitats,
except for Macrozoarces americanus and Brosme brosme which were
only observed at southern New England sites and Sebastes sp.
which was seen only at Baltimore and Norfolk Canyons.

Pueblo Habitats

These habitats have been illustrated and described (Warme et
al. 1977; Cooper and Uzmann 1977, 1980) by the former as "a
relatively localized area of submarine canyon wall where megabenthic
crustaceans and finfish have intensively bioeroded depressions and
borings into the substrate and have occupied these sites." Pueblo
habitat, occupied by tilefish, was commonly observed in Lydonia,
Veatch (the latter also by Warme et al. 1977) and Oceanographer
Canyons (Valentine et al. 1980). During our dives these habitats
were found from 170 to 245 m depth. We have never observed Pueblo
habitats around Hudson Canyon, even though we have made many more
dives there (Table 1). We observed, as did Warme et al. (1977) and
Valentine et al. (1980), that Pueblo habitats always occurred in the
stiff grey clay found as outcrops along the walls of many of the
submarine canyons in the study area. The excavations in the
substrate occupied by tilefish were variable in shape and size. The
smallest were just large enough to admit the girth of the tilefish,
while others were as much as 1 m wide by 3 m long, and 1 m deep.
They often had multiple openings into a single layer space (grotto) .
Dye marker experiments revealed that large and small openings into
the grottos from the substrate surface were common and numerous.
The openings not constructed by tilefish result from the burrowing
activity of several associated species (Table 2) .

The behavior of tilefish occupying Pueblo habitats was similar
to those in excavations under rock slabs, but different from
boulders. When approached by the submersible, tilefish always
entered head first, and then usually pressed themselves against the
back of the grotto and remained motionless. Exits from the grotto
were tail first or head first. Following acclimation to the
submersible, tilefish would leave the grotto but remained in the
immediate vicinity (within 2-3 m) . If disturbed, they moved
directly back into the grotto and became motionless again.

Individual tilefish may be long-term residents of the same
Pueblo habitat. We independently identified (using fish size and
various body scars and marks) the same two adult tilefish at the
same location approximately one year apart.

Habitat very similar to Pueblo habitat was observed on the
north wall of Norfolk Canyon between 175 and 247 m. This habitat
consisted of extensive, heavily bioeroded areas of stiff grey clay
that was topographically complex, with several large clay blocks
thrust up above the substrate with vertical walls and overhangs 25 m

Table 2 . Fishes and crustaceans observed at various tilef ish
habitats along the northeast coast of the U.S. during 1980-1983.
Each species was observed every year (see Table 1) unless otherwise
noted. HC = Hudson Canyon, VC = Veatch Canyon, LC = Lydonia Canyon,
BC = Baltimore Canyon, and NC = Norfolk Canyon (from Grimes et al.
1986) .

Species

Boulders

Pueblo

Vertical

and rocks

habitats

burrows

Crustaceans

Munida sp.a*

VC,LC

Munida longipes

—

Cancer sp.

VC,LC

VC,LC,HC

Acanthocarpus alexandria

—

Homarus americanus

VC,LC

VC,LC,HC

Bathynectes superba

goneplacid (possibly

—

VC,HC

Chacellus filiformis)

Fishes

Conger oceanicus

VC,LC

VC,HC

Macrozoarces americanus

VC,LC

—

Brosme brosme

VC,LC

—

Anthias nicholsi

VC,LC,

VC,LC,NC

VC,LC,HC

Helicolenus dactylopterus VC,LC,

VC , LC , NC

VC,LC,HC

Sebastes sp.

—

Urophycis sp.

—

Laemonema sp. (possibly

—

L. barbatum)

a. Three species have been

identified

from collected specimens: M.

iris, M. valida, and M.

forceps.

However, it is

not possible to

distinguish them from submersible sightings or photographs.

high. Tilef ish were observed inhabiting the largest of the grotto-
like excavations (up to 2 m greatest distance across the opening) .

Although these Norfolk Canyon habitats were physically very
similar to Pueblo habitats, they were quite different biologically
(Table 2) . Numerous anemones (Halcurias pilatus) living attached to
the burrowed clay characterized the community in Norfolk Canyon.
Anthias nicholsi was common, along with Sebastes sp. , the galatheid
crab Munida longipes and the portunid crab Bathynectes superba.

Vertical Burrows

We believe vertical burrows are the primary habitats of
tilefish in the Middle Atlantic and southern New England area (Able
et al. 1982; Grimes et al. 1986). Vertical burrows, especially
larger ones, were funnel-shaped and extensively secondarily burrowed
by associated species along the upper margin. The larger secondary
burrows located at the burrow margin were connected to the main
burrow shaft. Burrows were contagiously distributed. By compiling
the frequency distributions of distances between all adjacent

burrows observed on transect dives we determined that 27% of all
burrows seen at Hudson Canyon were less than 20 m apart (Grimes et
al. 1986).

Burrows were observed over greater depth ranges around Hudson
Canyon (120-225 m) and at the Middle Grounds (102-243 m) , than at
the two more northern submarine canyons (Veatch Canyon 12 0-165 m;
Lydonia Canyon 125-183 m) . At Veatch Canyon and Lydonia Canyons,
where boulder and Pueblo habitats also occurred, vertical burrows
were in shallower water. Largest burrows were observed at Hudson
Canyon (Table 3; mean depth = 1.7 m, range = 1.25-2.3 m, n = 6).
Burrows estimated to be up to 5.0 m in diameter were observed but
not measured because they were too large to appear entirely within

Table 3. Diameter (mean and range in m) of tilefish burrows near
submarine canyons in the Mid-Atlantic-Southern New England area; n =
number of burrows measured (from Grimes et al. in press).

Study Area

1980

1981

All

Hudson Canyon

1.57
(0.8-3.5)
n = 26

1.6
(0.3-3.0)
n = 25

1.6
(0.3-3.5)*
n = 51

Veatch Canyon

0.89
(0.4-2.0)
n = 20

0.84
(0.3-1.5)
n = 20

0.88
(0.3-2.0)*
n = 40

Lydonia Canyon

0.88
(0.5-1.2)
n = 6

*Mean burrow diameters for Hudson and Veatch
significantly different [t = 6.73, t(.05) = 0.99].

canyons

are

the photographic field of view. Burrows were generally smaller
(Table 3) , less secondarily bioeroded, less funnel shaped and less
dense (Table 4) at dive locations north of Hudson Canyon. In fact,
burrows at Hudson Canyon were on the average twice as large (upper
cone diameter) , over eight times more dense and much more complex
than burrows at Lydonia Canyon. We believe that geographic
differences in burrow habitats indicated that habitats at the more
northern dive locations were less temporally stable. The temporal
instability probably resulted from the greater seasonal variations
in bottom temperatures at more northern dive locations (Grimes et
al. 1986).

We hypothesized that the conical upper
burrows results from the combined activity of
associated species that inhabit burrow margins
which inhabit the smallest secondary burrows

portion of larger

tilefish and the

Galatheid crabs,

in burrow cones,

displace sediments into burrows and these sediments are forced out

(119-
n =

624
-1429)
= 6

(67-
n

145

-322)

= 3

Table 4. Density (mean and range) of tilefish burrows per km2 near
submarine canyons of the Mid-Atlantic-Southern New England area
based on submersible transects; n = number of transects (from Grimes
et al. in press) .

Study area 1980 1981 1982 All

Hudson Canyon 1815 1239 1132 1234

(952-2434) (1011-1548) (592-1646) (592-2434)
n = 4 n = 2 n=6 n = 12

Veatch Canyon 958 772

(119-1429) (748-798)
n = 4 n = 2

Lydonia Canyon 233 13 0

(67-164)
n = 1 n = 2

of the central shaft by tilefish swimming movements. Secondary
burrows that interconnect to the main burrow make the upper portion
of some tilefish burrows "honey combed" and prone to eventual
collapse. Additionally, we observed clay clumps near occupied
burrows that suggested to us that oral excavation by tilefish was an
important means of burrow construction. These mechanisms explain
the formation of conical shaped burrows, but do not account for the
larger diameter (estimated up to 9-10 m across) crater-like features
that we observed. These U-shaped features were secondarily eroded
like funnel-shaped burrows, and had as many as three individual
burrow shafts dug into their lower portions. Craters probably
formed by the coalescence of closely spaced vertical burrows that
widened and deepened.

Some burrows may be very old, if they are occupied by
successive generations of tilefish (individuals live in excess of 30
yrs, Turner et al. 1983, and the clay into which they are dug is
Pleistocene) . However, a recent experiment suggested that if a
burrow were unoccupied it would fill with sediment in maximum time
of one year. We removed the fish from a large burrow (2 m
diameter) , marked the burrow location with an acoustic transponder.
When we returned one year later the burrow was almost completely
silted in and unoccupied.

Species that are sparse over open bottom are concentrated in
and around burrows, forming a definite "tilefish community" (Table
2) . Approximately 60-80% of all galatheid crabs, cancrid crabs and
blackbellied rosefish counted in photographs were associated with
burrows. At times of peak activity as many as 2 galatheids, 5
goneplacids, 5 Anthias sp., 1 Urophycis sp. and 1 Helicolenus
dactylopterus were photographed at a single large (2 m diameter)
burrow.

Time-lapse photography revealed distinct activity patterns for
some associated species listed in Table 2 (Fig. 3) . Galatheid crabs
were more freguently photographed during the day, as were Anthias

nicholsi. H. dactylopterus may be crepuscular because they were
most frequently photographed during early morning and late after-
noon. Urophycis sp. activity showed no particular periodicity.
Goneplacid crabs were clearly nocturnal, never appearing in photo-
graphs exposed after 0810 hr and before 1910 hr.

Small crabs and fishes probably concentrate around burrows for
several reasons. They all appear to be shelter seeking and the
complex topography of the burrow provides that. The goneplacid and
galatheid crabs are also burrowers and the exposed clay in burrows
may be the best malleable substrate available. Also, the swimming
actions of tilefish probably keep their small secondary burrows at
least partially free of fine silt. Finally, if tilefish feeding and
excretion make the burrow a more resource rich environment, then
associated species may gain trophic rewards. Whatever the exact
nature of the benefits of burrows, the advantages gained must exceed
the disadvantages of danger from predation, because some associates
(in particular galatheid crabs, cancrid crabs and probably
Helicolenus dactylopterus ) are components of the diet of tilefish
(Turner and Freeman in prep.).

As in the case of Pueblo habitats, tilefish seemed to orient to
a particular burrow, especially around Hudson Canyon. In numerous
instances when rotenone was injected into burrows fish exited but
remained nearby, and in some instances attempted to re-enter the
burrow. These fish had not been incapacitated by the rotenone as
they quickly swam away when touched by the submersible manipulator
arm.

Most direct in situ observations have indicated single occupancy
of burrows. However, time-lapse photographs showed a male and
female (sexes distinguished by larger adipose crest in males)
utilizing the same burrow and displaying definite temporal activity
patterns (Fig. 3) . The female was seen repeatedly in photographs

1800 2000 2200 2400 0200 0400 0600 0800 1000 1200

400

100
80
60
40
20

i ' i i i i i 1 l 1 1 1 1 1 i i i i i i i i

20
10

: /a/^^M^

4
2

\„ * r^^^K^Ar^f\fT\

6
4
2

- AVaa . ^A.^./^-VV^aV

—\

4
2

: AaaV/n/ - "^-a^ Ayv-vr-yj\A

4
2

: ^-\/\ J\ . /^\A „ „

M u n i d a sp

Goneplacid crabs

Lopholatilus

chamaeleonticeps

Anthias nicholsi

Urophycis sp.

Hel i colenus
dactylopterus

Figure 3. Temporal activity of tilefish and several associated
species at a vertical burrow in Hudson Canyon, determined from
time lapse photographs (from Grimes et al. 1986).

from about 1630 to 2230 hr. mostly entering and/or exiting the
burrow, and seldom hovering above or around the burrow. At about
2230 hr the male appeared and was observed until 0700 hr, usually
above the burrow margin or central shaft. We do not know if the
female was in the burrow. However, because the male was not seen
entering or exiting the burrow may suggest this was so. From 0700
hr until 1500 hr the female was observed near the burrow in very few
photographs taken between 0900-1000 hr and 1100-1200 hr. This may
suggest that for the most part both sexes were away from the burrow
foraging during the day.

The non-corresponding temporal activity patterns of tilefish
and some associated species (galatheid crabs, A^ nicholsi, Urophycis
sp. and H^ dactylopterus ) and the knowledge that these species are
prey of tilefish (Turner and Freeman in prep.) suggested that
predation was a powerful organizing force in communities associated
with burrows, and probably Pueblo habitats as well. The burrow and
Pueblo village associated communities are complex ecological systems
featuring physical and biological interactions with tilefish acting
as a keystone (Paine 1966) species. They shape the habitat and
provide a physically suitable environment (perhaps trophically
advantageous as well) for other members of the community. They
interact with galatheid and goneplacid crabs to further structure
and develop the habitat. Finally, they enjoy a symbiosis (probably
mutualistic) with at least galatheid crabs, and through predation
probably influence community structure. Clearly, the exact nature
of the relationships between tilefish and associated species (i.e.
trophodynamics and the possibility of an unusually efficient flux of
nutrients through the community) are fertile areas for future
research.

Sea Floor Processes

Bioerosion is increasingly recognized as an important process
generating sediment and shaping bottom topography along the
continental margin (Warme and Marshall 1969; Dillon and Zimmerman
1970; Stanley 1971; Warme et al. 1971; Rowe et al. 19.74; Cacchione
et al. 1978; Ryan et al. 1978; Warme et al. 1978; Valentine et
al. 1980; Malahoff et al. 1981; Hecker 1982). On the outer
continental shelf tilefish play an active role in eroding the sea
floor as described in previous sections of this paper.

The outer continental shelf off New Jersey and Long Island is
mostly shaped by an evenly spaced linear northeast-southwest
trending ridge and swale topography. However, around Hudson Canyon
this regular topography is replaced by an irregular hummocky
topography (Fig. 4; Ewing et al. 1963; Knebel 1979). The area
covers about 800 km and occurs mostly at depths between 120 and 500
m. Hummocks are irregularly spaced and have 1-10 m relief. The
hummocks are clearly erosional because horizontal reflectors are
truncated at the flanks. Because of the proximity of the rough
topography to Hudson Canyon the features have been attributed to
canyon related processes (Ewing et al. 1963; Knebel 1979). Our
knowledge of tilefish, habitat, ecology and behavior has led us to
hypothesize that bioerosion by tilefish may be the cause of the
rough bottom topography (Twichell et al. 1985) .

There is a close correspondence between the fishing grounds for
tilefish and the extent of the rough topography: Fig. 4 outlines the

39°45'N

39'30'N

39°I5'N

KILOMETERS
CONTOURS IN METERS

72045 W

72°30'W

72°I5'W

Figure 4. Comparison of the extent of the rough topography around
Hudson Canyon with the extent of the tile fish grounds (from
Twichell et al. in press).

location of 1634 individual longline sets made from 1978-1982, as
well as the extent of the rough topography.

Stratigraphic data supported our contention that the hummocky
topographic features were Holocene rather than Pleistocene in age.
Seismic profiling showed three distinct layers. The oldest layer,
an acoustically massive layer that was exposed north of Hudson
Canyon, consisted of medium to coarse sand. Overlying the massive
layer was a well laminated layer that observations from a
submersible showed to be stiff grey clay, and it was this layer that

was burrowed by tilefish. The uppermost layer was composed of
Holocene sand (13,000 yrs old) that was only seen shoreward of the
area of rough topography. The rough topography coincided with the
area where the laminated clay layer was exposed on the sea floor.
Where the clay was buried by Holocene sand, the upper surface of the
clay was smooth, indicating that the rough topography was younger
than 13,000 yrs, otherwise the clay surface that was buried would
also be rough (Twichell et al. 1985).

Grain size analysis of sediment samples taken across the three
stratigraphic layers indicated three distinct sediment populations.
The largest and smallest size fractions were medium to coarse sand
that characterized the Holocene sand sheet shoreward of the rough
topography, and silty-clay that characterized the burrowed
substrate. The third sediment type was a thin veneer (less than 1
m) of sediment that covered much of the rough topography away from
burrows; it was a mixture of the silt-clay excavated by tilefish,
and sand transported offshore from the Holocene sand sheet.

The basic process of burrow construction and maintenance
through the combined activities of tilefish and associated species
over time may provide the mechanism for forming the rough
topography. Considerable maintenance of the burrows is required;
the vacant burrow we revisited after one year was silted in. Thus,
sedimentation was considerable, and a fish must do considerable
work to maintain a burrow. Such a rapid .rate of filling suggests
that juveniles probably do not occupy large existing burrows because
they could not maintain them. Therefore, successive generations of
tilefish would mostly dig new burrows rather than occupy old ones.
Also, we frequently observed clouds of fine sediment coming from
burrows, and once suspended it was evidently transported away by the
current because there were not sediment mounds around burrows. Much
of the suspended sediment may have been lost to the upper
continental slope because mean drift in the area is 8 cm/sec to the
south.

Having identified a mechanism for sea floor bioerosion we
evaluated its extent by using sidescan sonar to determine the
spatial distribution of tilefish burrows. Sidescan sonographs
showed burrows only in areas where the clay layer was exposed at the
surface of the substrate (Fig. 5 - upper panel) . Our interpretation
of burrows seen on sonographs was validated by direct observation
during submersible dives.

We also used sidescan sonar to estimate mean burrow density
(2 500/km2 ) , and combined that information with the calculated
sediment volume in a 2 m diameter burrow (1.3 m assuming a perfect
conical shape 1.5 m deep) to estimate the amount of sediment removed
from the 800 km area; that amount was 2.6 million m3 Since each
generation of fish mostly dig their own burrows, rather than occupy
existing ones, the amount of sediment removed would be much more
than the amount removed to form the present burrows.

Thus, tilefish effectively remove large sediment volumes.
However, how can burrowing form large scale hummocky topography
given that individual burrows and the rough topography were of very
different scales? We believe that the larger scale hummocky
topography is a consequence of spatially differential erosion rates
over a long time period. Our analysis of the spatial distribution
of burrows, i.e., frequency distribution of the distances between

150-

Figure 5. Sidescan sonograph (upper panel) and 3.5 kHz profile
(lower panel) on the eastern side of the Hudson Canyon. On the
sonograph, tilefish burrows are evident as points of strong acoustic
reflectance with a shadow in front of them. The 3.5 kHz profile
shows the rough topography and laminated clay substrate on the left
portion of the record, its erosional truncation, and the exposure of
the underlying sand on the right part of the record. Note the
disappearance of tilefish burrows at the boundary of the clay
substrate (from Twichell et al. 1985).

adjacent burrows (taken from sidescan sonographs and from direct
measurements along submersible transects) , showed that burrows were
contagiously distributed (Twichell et al. 1985). In areas where
burrows were clustered, bioerosion should be more rapid than where
burrows were scarce. Furthermore, the dimensions of burrow clusters
(up to 200 m across) were similar to the size of the larger

depressions separating the hummocks.

In summary, we have proposed that tilefish are responsible for
the extensive bioerosion of bottom sediments around Hudson Canyon.
By burrowing (and individual burrows coalescing to form craters) in
clusters for the past 8 to 10 thousand years they have created the
large scale hummocky topography.

ACKNOWLEDGEMENTS

Tilefish research was initiated at the urgings of our friend
the late Lionel Walford. We would like to thank the following
individuals and institutions for their assistance in this research
effort: Dick Cooper and Joe Uzmann, National Marine Fisheries
Service, Northeast Fisheries Center, Woods Hole, Mass., introduced
the first two authors to the application of submersibles to science,
and later helped to identify potential dive sites in Veatch and
Lydonia Canyons. Barbara Hecker, Lamont Doherty Geological
Observatory, and Ken Sulak, Virginia Institute of Marine Science
suggested dive sites in Baltimore Canyon and Norfolk Canyon,
respectively. Austin Williams, National Marine Fisheries Service,
Systematics Laboratory, identified the galatheid and goneplacid
crabs. We thank the captains and the crews of the support ships R/V
Johnson and R/V Atlantic Twin, and the Johnson-Sea-Link and Nekton
Gamma submersible pilots and crews for their cooperation and
professionalism. Portions of this work would not have succeeded
without the cooperation of many commercial longline fishermen. In
particular, we thank captains John Larson, Louis Puskus, Ron Minor,
Mike Ciell and Angie Ciell. Support for this research was provided
by the National Oceanic and Atmospheric Administration, National Sea
Grant and Office of Undersea Research programs, New Jersey Sea Grant
and Harbor Branch Foundation. Additional assistance from the New
Jersey Agricultural Experiment Station (AES 12409) , Center for
Coastal and Environmental Studies, and Research Council, all of
Rutgers University is also acknowledged.

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habitat for fishery resources.
Cacchione, D.A. , G.T. Rowe, and A. Malahoff. 1978. Submersible

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Stanley, D. J., and Kelling, G. (eds.), Sedimentation in

Submarine Canyons, Fans, and Trenches. pp. 42-50. Dowden,

Hutchinson and Ross, Stroudsburg, Penn.
Cesney, J.W. 1972. Use of the SYMAP computer mapping program.

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Christ, W.R., and J.L. Chamberlain. 1979. Temperature structure

on the continental shelf and slope south of New England

during 1976. In: J. R. Goulet, Jr. and E.D. Haynes (eds.).

Ocean variability in the U.S. Fishery Conservation zone.

pp. 315-335. NOAA Tech. Rep. NMFS Circ. 427.
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adult clawed lobsters, Homarus americanus, Homarus

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no. 7, 300 p.
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(Perciformes: Branchiostegidae and Malacanthidae) , with

description of two new species. U.S. Dept. of Commerce,

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NEFC, Sandy Hook, NJ, Tech. Ser. Rep.
Grimes, C. B. , K. W. Able, and R. S.

Lopholatilus chamaeleonticeps

community structure in Middle

England waters. Env. Biol. Fish.
Grimes, C.B., K.W. Able, and S.C.

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Massachusetts Institute of

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5, 41 p.

Jones. 1986. Tilefish
habitat, behavior and
Atlantic and southern New
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Turner. 1980. A preliminary
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Grimes, C. B. , K. W. Able, and S. C. Turner,
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chamaeleonticeps ; evidence for social
reproduction .
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Soc. 111:94-98.

In prep. The

Lopholatilus

control of

Hecker, B. 1982. Possible benthic fauna and slope instability

relationships. In: S. Saxov, and J.K. Neiuwenhius (eds) .

Marine slides and other mass movements, pp. 3 35-34 0. Plenum

Press, N.Y.
High, W. L. 1980. Bait loss from halibut longline gear observed

from a submersible. U.S. NMFS, Mar. Fish. Rev. 42:2 6-29.
Katz, S. J., C. B. Grimes, and K. W. Able 1983. Identification of

tilefish stocks along the U. S. east coast and Gulf of

Mexico. U.S. Fish. Bull. 81(l):41-50.
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shelf around Hudson Canyon. Mar. Geol. 33:67-75.
Malahoff, A., R. W. Embley, and D. J. Fornari. 1982.

Geomorphology of Norfolk and Washington Canyons and the

surrounding continental slope and upper rise as observed

from DSRV ALVIN In: R. Scrutton (ed.), Ocean Floor: Bruce

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records of Canadian fishes and the influence of hydrography

on resident and non-resident Scotian shelf ichthyofauna. J.

Fish. Res. Board Can. 37:49-65.
Robertson, J. C. 1967. The SYMAP program for computer mapping.

Cartographic Journal 4:108-113.
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biological reworking of sediments in Hudson Submarine

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Ryan, W. B. F. , M. B. Cita, E. L. Miller, D. Hanselman, W.D.

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mortality, and age/size structure of the fisheries for

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Mid-Atlantic Fishery Management Council on the Rutgers

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Turner, S. C. , and B. L. Freeman. In prep. Food habits of

tilefish, Lopholatilus chaemaeleonticeps , in Mid-Atlantic

waters.
Twichell, D. C. , C. B. Grimes, R. S. Jones, and K.W. Able. 1985.

Bioerosion on the outer continental shelf near Hudson

Submarine Canyon. J. Sed. Pet. 55(5): 712-719.
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December 1979. NOAA, NMFS, Cur. Fish. Stat. 7973 1980b.

New York landings, December 1979. NOAA, NMFS, Cur. Fish.

Stat. 7979. 1980c. Rhode Island landings, December 1979.

NOAA, NMFS, Cur. Fish. Stat. 7975.

Uzmann, J. R. , R.A. Cooper, R. Wigley, W. Rathjen, and R. Theroux.

1978. Synoptic comparison of three sampling techniques for

estimating abundance and distribution of selected

megabenthos: submersible vs. camera sled vs. otter trawl.

NOAA Mar. Fish. Rev. Paper 1273, 39 (12) : 11-19 .
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and biology of Oceanographer submarine canyon. Mar. Geol.

38:283-312.
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occupying the outer banks off the southern coast of New

England and some additions to the fauna of Vineyard Sound.

Amer. J. of Sci. 24 (3) : 360-371.
Warme, J. E. and N. F. Marshall. 1969. Marine borers in

calcareous terrigenous rocks of the Pacific Coast. American

Zoologist 9:765-774.
Warme, J. E., T. B. Scanland, and N.F. Marshall. 1971. Submarine

canyon erosion: Contribution of marine rock burrowers.

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Warme, J. E., R. A. Slater, and R.A. Cooper. 1977. Bioerosion in

submarine canyons. Chapter 6. In: D. J. Stanley and G.

Kelling (eds) . Submarine Canyons, Fan and Trench

Sedimentation. pp. 65-70. Dowden, Hutchinson and Ross, Inc

Stroudsburg, Pennsylvania.

NOAA Symp. Ser. for Undersea Res. 2(2), 1987 71

OBSERVATIONS OF GELATINOUS ZOOPLANKTON AND MEASUREMENTS OF
VERTICAL BIOLUMINESCENCE IN THE GULF OF MAINE AND ON GEORGES BANK

Carolyn A. Griswold
National Marine Fisheries Service, Narragansett, RI 02882

Jon R. Losee
Naval Oceans Systems Center, San Diego, CA 92152

ABSTRACT

Gelatinous zooplankton, in particular the physonect
siphonophore Nanomia cara, have been implicated as gill net
fouling organisms in the Gulf of Maine. They are also considered
potential predators of larval fish. However, little is known of
these fragile organisms* natural history and behavior because
standard sampling methods provide little more than indices of
relative abundance and distribution. In response to the need to
learn more about gelatinous organisms and their impact on
fisheries, a cooperative project entitled "Water Column Ecology"
was initiated in 1982. As part of this program in situ
observations of behavior, size density, distribution, associated
species and environmental parameters were made using the research
submersibles Nekton Gamma and Johnson Sea-Link. This cooperative
project also included Naval Ocean Systems Center personnel who
made in situ measurements of vertical bioluminescence. These
profiles were later correlated with the observed plankton
community and samples collected throughout the water column.

INTRODUCTION

Gelatinous zooplankton, in particular the physonect
siphonophore Nanomia cara, have been implicated as gill net
fouling organisms in the Gulf of Maine. They have undergone two
population explosions in past years - one in the winter of 1975-76
and again in 1981-82. During those periods they reduced gill
net fishing efficiency by as much as 90%, which resulted in
substantial economic losses to fishermen of northern New England.

Siphonophores, an order of Coelenterata, are divided into
three suborders: The Calycophorae (Lenchart, 1854) which have no
nectophores and no float, the Cystonectae (Haechel, 1888) which
have a large float and no nectophores such as Physalia, the
Portuguese Man O'War, and the Physonectae (Haechel, 1888) which
have nectophores and a small float; Nanomia cara (Figure 1)
belongs to the latter (Totten, 1965) . Agassiz (1865) first
described N_j_ cara. including the juvenile stages, from specimens
he collected in Massachusetts Bay. Little about this organism's
biology has been added to the information Agassiz provided over
one hundred years ago. Bigelow (192 5) states that N_j_ cara is the
only siphonophore which is a regular inhabitant of the Gulf of
Maine. While it is common in the Gulf of Maine, he did not find
it along the south or west coasts of Cape Cod and only rarely on
Georges Bank during his two year sampling period.

NANOMIA CARA

V~"nectophore 7 X

GASTROZOOID

SCALE:

i 1 10mm = 2 5 mm, or 4X

ENLARGED STRUCTURES

i 1

10.5 mm = 1.5 mm, or 7 X

Figure 1. Nanomia cara is a physonect siphonophore endemic to the
Gulf of Maine.

Very little is known about this particular organism;
however, recent information (Purcell 1981a, b) has shown that many
siphonophores are either occasional or common predators on fish
larvae. Lough (1976) and Larson (Peter Larson, Bigelow
Laboratory, W. Boothbay Harbor, ME, personal communication) noted
an inverse relationship between siphonophores and fall spawned
herring larvae in the Georges Bank/ Gulf of Maine areas during the
periods of the two recent "blooms".

Because of the fishery implications of this organism, a
program was established in late 1975 in an attempt to learn more
of its natural history, if only to be able to predict years or
areas of bloom conditions as an aid to local fishermen.

METHODS AND RESULTS

Plankton Survey

The first approach was to look at zooplankton samples taken
in the Gulf of Maine and on Georges Bank during the fall and
winter of 1975 and spring of 1976. These samples were collected
as part of the Northeast Fisheries Center's (NEFC) MARMAP (Marine
Resources Monitoring, Assessment, and Prediction) program. We
used 61 cm paired bongo nets (0.505 and 0.333 mm) and did double
oblique tows from the surface to 2 m above the bottom or to a
maximum of 2 00 m.

These recent surveys of siphonophore distribution and
abundance bear out several of Bigelow' s (1924) suppositions. One
is that they are most abundant in fall and winter (Rogers -
Griswold nee Rogers, 1978) with decreasing abundance in spring
(Rogers, 1979) . Based on these studies and reports from local
fishermen in years of high abundance, one center of population
density appears to be the western Gulf of Maine, probably
representing a resident population.

MARMAP survey samples have also yielded
siphonophores, presumably N_j_ cara, in the Northeast Channel around
the Scotian Shelf and into the Bay of Fundy. Generally this
population is of smaller size and appears discontinuous with the
more western population. Sameoto (1982) found N_s_ cara was the
predominant siphonophore in shelf waters off southeastern Nova
Scotia. However, it was not found in slope waters of the same
area. It is likely therefore that some N_s_ cara enter the Gulf of
Maine through the Northeast Channel in the upper 75 m which is
Scotian Shelf water. Some of the population extends around the
southern coast of Nova Scotia, up into the Bay of Fundy and along
the eastern coast of Maine. Redfield (1936) followed a population
of Limacina retroversa as it entered through the Northeast Channel
area. The distribution of recent immigrants is somewhat similar
to what we found for N. cara (Rogers, 1979) .

Bigelow (1926) noted that N_;_ cara is rarely found on Georges
Bank. Our study (Rogers, 1978) corroborates this, although some
are found in the Great South Channel area. On a recent cruise
(Knorr 94, June 1982), SCUBA divers including myself, made a dive
at the edge of the shelf off southern New England (40°10.04'N,
70°59.97'W). Siphonophores were extremely abundant in the upper
30 m (10°C) . The predominant species was Agalma elegans, but N.
cara was also present. This indicates that N^ cara's southern

distribution may be restricted to shelf/slope water fronts rather
than more coastal waters south of Cape Cod. This organism is also
common off the U.K. (Fraser, 1967) .

Continuous Plankton Recorders

Monthly continuous plankton recorder (CPR) data for 1981 in
the Gulf of Maine from Boston, MA to near Cape Sable, NS indicated
that a swarm of siphonophores began in the central Gulf of Maine
in late June- July and spread across the Gulf from Cape Ann to Cape
Sable by September when estimates of abundance were highest. The
population either decreased or, more likely, was below the 10 m
CPR depth in November. An alternate explanation was that the
population sampled on the Scotian Shelf came from the east (Daniel
Smith, Atlantic Environmental Group, Narragansett, RI) . We have
continued to examine the MARMAP samples and CPR records for
siphonophores; in addition, we initiated two short cruises in fall
1982 and 1983 to conduct a special survey because of a second
bloom in the 1981-82 winter-spring period.

Ongoing MARMAP plankton surveys, special surveys and CPR
records can indicate presence or absence of these organisms.
However, these types of sampling programs provide only relative
information on areal distribution and seasonal abundance because
of the patchy horizontal and vertical distribution of N^ cara
populations, which are often at depths greater than is routinely
sampled, and the fact that parts of the organism most easily
recognized are readily fragmented and may not be sampled.

SCUBA

SCUBA can be used successfully for collections and
observations of many fragile gelatinous organisms (Hamner et al.,
1975; Harbison and Madin, 1979). However, its use is not
practical in the cold, deeper waters of the Gulf of Maine on a
regular basis.

Manned Submersible Studies

Gelatinous Zooplankton

In past studies, gelatinous zooplankton abundance, size and
distribution have been adequately estimated through the use of
manned submersibles (Barham, 1963, 1966). Therefore, in June 1976
following intensive MARMAP surveillance of the area (Rogers,
1979) , we conducted a number of submersible (Nekton Gamma ) dives
in Wilkinson Basin (Western Gulf of Maine) to estimate the
abundance and density of N^. cara and establish its daytime depth
distribution (Rogers et al, 1978). We found siphonophores only at
stations where the water depth was >72 m and only below the
thermocline in a temperature range of 5.5-7.5°C. Generally,
larger colonies were found at greater depths than the smaller
ones. Density ranged from <0.1 to 8/m3 . No salinities were taken
at the time so a profile of salinity preference and possible water
mass origin was not possible. These preliminary dives and the
subsequent (1981-82) "bloom" of these organisms indicated that
more needs to be known concerning the life history and
distribution of this important animal.

74°

42°-

40°-

VEATCH CANYON*

ANYON^ •a,^

7 v^ HYDROGRAPHER
CANYON

72°

I
70°

68°

66*

— A A°

44<

-42"

-40*

Figure 2. Location of dive sites for the 1983 Johnson-Sea-Link
Water Column Ecology cruise.

In the fall of 1982 we developed a submersible proposal
entitled "Water Column Ecology" . It was new type of proposal from
the NEFC in that it focused on water column communities and
environmental parameters rather than on the benthos. The proposal
was funded jointly by NOAA and the Harbor Branch Foundation (HBF)
which owns and operates the Johnson-Sea-Link submersible system.
The project was a cooperative effort between Dr. Marsh Youngbluth
of the Harbor Branch Foundation; the U.S. Navy, in particular Dr.
Jon Losee and David Lapota, Naval Ocean Systems Center (NOSC) ; and
Carolyn Griswold, NEFC, National Marine Fisheries Service. Dr.
Kurt Stehling, NOAA, acted as coordinator for the project. We had
three main areas of interest: marine snow (HBF) , vertical
distribution of bioluminescence (NOSC) , and gelatinous zooplankton
(NEFC) . Because of its possible impact on fisheries, N^. cara was
designated the target species for the 1983 Johnson-Sea-Link
mission.

We occupied 7 stations, 4 along a permanent MARMAP transect
in the Gulf of Maine and three in Hydrographer and Veatch Canyons
(Figure 2) from July 10-17, 1983. All dives were made during the
dark between 2 000 and 0500 hours. Three two-hour dives were made
each night.

A series of seven dives were made at depths ranging from 2 00
m in the Gulf of Maine to 600 m in Veatch and Hydrographer Canyons
during which observations and collections of gelatinous
zooplankton were made as well as observations of co-occurring
species. Vertical bioluminescence was measured during each of
these dives. Methods and combined results of bioluminescence and
species distribution observations will be described below.

N. cara was observed at each station although not on every
dive. Individual colonies ranged in size from 0.2 to 2.0 m in
length. This size range is considerably smaller than our previous
submersible observations where individuals up to 3.7 m were
observed. Maximum density on one dive was 3/m3 , but generally it
was orders of magnitude less during this mission and less than had
been reported earlier (Rogers et al., 1978).

Vertical distributions of siphonophores varied from a
relatively narrow band of 91 m on one dive to over 274 m. The
total vertical range for animals observed during all the dives was
27 m below the surface to 568 m. Most colonies occurred below the
thermocline at temperatures of approximately 6° C, however, on one
dive siphonophores were observed at 13.0° C. Although the
organisms were widely distributed vertically, it was difficult to
ascertain whether or not this was a result of diel migrations or a
normal distribution pattern. Our failure to verify whether or not
migrations were occurring lies in the fact that the animals were
so sparsely distributed that directed movement could not be
determined.

A total of 2 6 siphonophores were captured alive and intact
from the submersible, an impossible task using conventional net
gear. Each was preserved and later analysis of stomach contents
showed that dominant food items were copepods (Calanus
f inmarchicus. Acartia sp. , and Metridia lucens) followed by
euphausiids (Meganyctiphanes norvecrica and Thysanoessa spp.) and
amphipods (Parathemisto sp.). One arrow worm (Saqitta sp.) and
one house fly (Diptera sp.) also had been ingested.

Visual observations and identification of potential
zooplankton prey species from the submersible sphere correlated
well with that which was ingested by the siphonophores. Both the
size range and type of prey support the supposition that N_i_ cara
is an opportunistic feeder and an omnivore, so the hypothesis that
larval fish would be a likely prey in areas or times when
predator-prey densities are high seems a reasonable assumption.
On-board feeding studies using larval fish are planned for the
immediate future to verify the possibility of such a
relationship .

Vertical Bioluminescence

During each dive vertical bioluminescence was measured and
later correlated with recorded observations of zooplankton
community structure. Bioluminescence was measured using both open
and pumped detectors mounted on the outside of the submersible
forward of the sphere. Only the pumped or closed system detector
will be discussed here. The detector consists of a
photomultiplier tube (PMT) (RCA 857A) and the associated
electronics fitted in a Benthos pressure housing (12.7 cm O.D. x
56 cm length) which is pressure tested to 7000 m of seawater. The
housing is fitted with a 3 cm thick ultraviolet transmitting
acrylic pressure window. The intake is an S-band of 7.5 cm I.D.
black plastic pipe used as a light baffle which is mounted facing
downward. A turbulent volume of seawater is obtained by pulling
seawater through the PMT "viewing" chamber (60 ml volume) by a
pump at a constant flow rate of 1 liter/sec. The PMT is used in
photon counting mode, and the PMT pulses are recorded in the
diving compartment of the submersible in two ways: average count
data (counts/60 sec) are obtained by use of an Ortec 874 scaler,
and every 60 sec, 10 sec scans of the PMT data are obtained with
10 msec resolution, using two Davidson 1024 multichannel
analyzers. The scaler and analyzer are controlled and their data
recorded by an Otrona Attache microcomputer (Figure 3) . Examples
of the 10 msec data and the average count data vs. depth are shown
in Figure 4.

In addition to in situ measurements, organisms including N.
cara were collected throughout the water column. The organisms
were returned to shipboard, isolated and placed in 5 ml vials in
running filtered seawater. They were held in the dark for 24
hours then placed in a laboratory detector, which consists of two
PMT's which view the vial. Each organism is stimulated to flash
when the water is drawn off by means of a vacuum pump leaving the
organism dry on filter paper in the vial. After the flash is
recorded the organism is removed and preserved for later
identification. An example of flash response from 1L cara can be
seen in Figure 5. Since each organism type has a typical
signature, these signatures will be used eventually to
characterize community structure from in situ measurements such as
those seen in Figure 5.

Schematic Of Bioluminescence Sensors
On The JSL Submersible

DIVING COMPARTMENT

DIVING SPHERE

OPEN

BIOLUMINESCENCE

DETECTOR

AERYUC
WINDOW

2-CHANNEL SCALAR
(PMT CTS/60 mc)

□ 1024
MULTI-
CHANNEL
ANALYZER
(PMT CTS/10m»)

OTRONA MINI-
COMPUTER + DUAL
DISK DRIVES (DATA

STORAGE + CONTROL)

[

JOHNSON SEA LINK SUBMERSIBLE

PMT ELECTRONICS

BENTHOS
PRESSURE HOUSING

PUMPED BIOLUMINESCENCE DETECTOR
SEAWATER INTAKE

Figure 3 . Schematic of the bioluminescence sensors for the
Johnson-Sea-Link . Only the pumped detector results are discussed.

DISCUSSION

When observations of vertical zooplankton community structure
and bioluminescence are combined little correlation can be seen
(Figures 6, 7) . Bioluminescence is highest in the upper 100 m
with a maximum usually occurring right below the thermocline.
This area corresponds to the chlorophyll maxima layer where
biomass and productivity are high. Results from organisms
collected from areas of high bioluminescent activity and tested in
the onboard system bear out the conclusion that the upper layers

perm- 4».b«**

- 29

, lil n i dull

Rtt/tARE/D MK I DAT 2

Ij11.li.iH

t94St7tttt
TIME SEC CCONSCC It MSEC TIME BINS)

Derm- us. en

Nttt/BAHE/D DIVE I DAY 2

D - » • i •^>- ■ ■ ■

TIME SEC CCONtEC It MSEC TIME KM)

DKH DAT-2 KSCEMT 7/11/83 »-2 WKI> CTS/WEC

UGH! 0UM:COU(TS/68SEr

Figure 4. The vertical bioluminescence profile (C) from Station 2
with two 10 msec time bin individual flash records from depths of:
(A) 50 m, and (B) 114 m.

SAMPLE 35 *36 NECTOPHORE 48MSEC 1 .6E4 FIRST PEAK

48 _

N
CO

38 .

- 28

18 _

4 8 8 18 12 14
TIME SEC CCONSEC 48 MSEC TIME BINS)

Figure 5. The bioluminescent "signature"
Nanomia cara nectophore.

from an individual

are dominated by small organisms not easily seen or adequately
identified by an observer. The bioluminescing population includes
dinoflagellates, copepods, larval euphausiids and radiolarians.
The larger more easily recognized organisms are widely
distributed, but usually occur below the thermocline. Many of
these are luminescent such as siphonophores, ctenophores,
euphasiids, some fish, squid and so on, but the bioluminescent
depth curve does not reflect this, indicating that these
organisms are not uniformly distributed. By combining both types
of observations a somewhat more complete view of the water column
community emerges; however, even that is biased by attraction to
or avoidance by organisms of the white lights of the submersible.
The picture is further complicated by the fact that when the
submersible lights are off large strings and other configurations
of bioluminescence can be seen. They are difficult to identify
and when the lights are turned on nothing recognizable can be
detected.

UGH OUTPUT: COUNTS/60 SEC
2000000 4000000

TEMPERATURE (°C)

8 12 16 20 22

WILKINSON
BASIN,

GULF OF
MAINE

Figure 6. The measured vertical bioluminescent profile and
observed zooplankton community from Station 2 . Dark circles
represent observed presence of organisms only.

In order to try to further identify such organisms, we are
proposing to use red, black or ultraviolet (uv) lights mounted on
the submersible. Patterns of fluorescence which would show up
under the ultraviolet lights could be video taped and possible
identifications made using image analyzer techniques.

LIGHT OUTPUT: COUNTS/ 60 SEC

O 200000 400000 600000

I 1 I I I l_i

TEMPERATURE (*C)

8 10 12 14 16 18
111111

z
o

Q-

^ S i m

s ? i o

^, D 5 uj

<J LU < CO

O
u

i—

HYDROGRAPHER
CANYON

Figure 7. The measured vertical bioluminescence from Station 6.
Bioluminescent activity does not correlate well with the observed
zooplankton community.

CONCLUSIONS

In order to solve problems regarding the natural history of
fragile gelatinous organisms such as Nanomia cara, no one method
of observation and collection is sufficient. Standard plankton
surveys provide information on relative seasonal abundance and
distribution. Continuous plankton recorder information can add to
that and give indication of centers of population activity and to
some extent origins of the populations. Information from these
sources together with published distributional data establishes
local population centers and areas of immigration. SCUBA also can
be employed to establish distributional patterns and is useful in
making in situ observations and collections. However, this method
is of limited value in the deep waters of the Gulf of Maine.

Use of submersibles has provided us with the best specific
information on size, vertical distribution, density, swimming
speed, and co-occurring species. Collections of living, intact
organisms verified identification and allowed for onboard
experimentation and analyses of stomach contents. Such
collections indicate that N^ cara has bioluminescent properties
and that it is a non-specific or opportunistic feeder, possibly
a predator of larval fish.

Comparisons of observed organisms and bioluminescence
throughout the water column indicates that small organisms not
identifiable to an observer are responsible for most of the
measured bioluminescence and these organisms are most abundant in
the upper 100 m with a maximum around the thermocline which also
represents the area of the productive chlorophyll maxima layer.
Large luminous organisms which can be identified by the observer
are not being sampled by the pump system, probably because of
their ability to avoid gear and because they are less numerous
than the small organisms.

New techniques are proposed for characterizing bioluminescent
forms not sampled or observed using normal methods.

ACKNOWLEDGEMENT

Special thanks are due Richard Cooper for his continuing
encouragement and support. Marsh Youngbluth has been extremely
helpful in all aspects of this project. David Lapota provided the
figure of the N^. cara bioluminescent signature. This paper is
dedicated to Helen W. Connington.

LITERATURE CITED

Agassiz, A. 1865. North American Acalephae Mem. M.C.Z. 1(2). 234

pp.
Barham, E.G. 1963. Siphonophores and the deep scattering layer.

Science 140: 826-828.
Barham, E.G. 1966. Deep scattering layer migration and

composition: Observations from a diving saucer. Science

151:1399-1430.
Bigelow, H.B. 1924. Plankton of the offshore waters of the Gulf

of Maine. Bull. Bur. Fish. XI (II). 968 pp.

Fraser, J.H. 1967. Siphonophora in the plankton to the north and

west of the British Isles. Proc. Roy. Soc. Edin. Sec. B.

LXX - Part 1 (1) :l-30.
Hamner, W.M. , L.P. Madin, A.L. Alldredge, R.W. Gilmer, and P.P.

Hamner. 1975. Underwater observations of gelatinous

zooplankton: Sampling problems, feeding biology and

behavior. Limnol. Oceanogr. 20: 907-917.
Harbison, G.R., and L.P. Madin. 1979. Diving - a new view of

plankton biology. Oceanus 22: 18-27.
Losee, J., D. Lapota, and S. Lieberman. 1985. Chapter 11.

Biolumoinescence. A new tool for oceanography? In: A.

Zirino (ed.), Advances in Chemistry No. 209. Mapping

Strategies in Chemical Oceanography, p. 211-234. American

Chemistry Society, Washington, D.C..
Lough, R.G. 1976. The distribution and abundance, growth and

mortality of Georges Bank - Nantucket Shoals herring larvae

during the 1975-76 winter period. Int. Comm. Northwest Atl.

Fish. Res. Doc. 76/VII/33, 30 pp.
Purcell, J.E. 1981a. Feeding ecology of Rhizophvsa evesenhardti .

a siphonophore predator of fish larvae. Limnol. Oceanogr.

26: 424-432.
Purcell, J.E. 1981b. Dietary composition and diel feeding

patterns of epipelagic siphonophores. Mar. Biol. 65: 83-90.
Redfield, A.C. 1936. The history of a population of Limacina

retroversa during its drift across the Gulf of Maine. Biol.

Bull. 76(1): 26-47.
Rogers, C.A. 1978. Impact of autumn-winter swarming of a

siphonophore ("Lipo") on fishing in coastal waters of New

England. In: J.R. Goulet, Jr., and E.D. Haynes (eds.), Ocean

Variability: Effects on U.S. Marine Fishery Resources

- 1975. NOAA Tech. Rep. NMFS Circ. 416: 333-350.
Rogers, C.A. 1979. Siphonophore ("Lipo") swarming in New England

coastal waters - update, 1976. In: J.R. Goulet, Jr., and E.

D. Haynes (eds.), Ocean Variability in the U.S. Fishery

Conservation Zone. 1976. NOAA Tech. Rept. NMFS Circ. 427:

349-352.
Rogers, C.A. , D.C. Biggs, and R.A. Cooper. 1978. Aggregation of

the siphonophore Nanomia cara in the Gulf of Maine:

Observations from a submersible. Fish Bull. 76(1): 281-284.
Sameoto, D.D. 1982. Zooplankton and micronekton abundance in

acoutic scattering layers on the Nova Scotian slope. Can. J.

Fish. Aquat. Sci. 39: 760-777.
Totten, A.K. 1965. A synopsis of the Siphonophora. British

Museum (Natural History) , London, 23 0 pp.

NOAA Symp. Ser. for Undersea Res. 2(2), 1987 85

DIRECT OBSERVATION IN PLANKTON ECOLOGY

G. R. Harbison

Biology Department

Woods Hole Oceanographic Institution

Woods Hole, MA 02543

ABSTRACT

Until recently, most plankton ecologists have relied on blind
sampling, mainly with towed nets, to study distribution patterns,
to collect organisms for experiments, and to infer behavior and
trophic relationships. As a result, plankton ecology has lagged far
behind terrestrial and nearshore benthic ecology. With the develop-
ment of in situ techniques, it is possible to observe the behavior
of planktonic organisms directly, to collect them in good condition
for experiments, and to study distribution patterns at scales as
small as a centimeter. Most of this work has been with SCUBA, so
that only a minute fraction of the organisms in the open sea has
been studied. Limited work with submersibles has demonstrated that
there is an abundant, as yet undescribed, mesopelagic fauna, with
complex and interesting interrelationships. To develop an under-
standing of the open ocean as an environment, it is essential that
we observe planktonic animals directly, and study behavior in situ,
as well as in the laboratory. At present, observations and collec-
tions with submersibles are the methods of choice, but future plans
should include an undersea research vessel capable of spending long
periods of time at depth.

Although most people consider the great age of biological
exploration as essentially over, to those of us working on plank-
tonic animals it has just begun. Three-quarters of the Earth is
covered by water, at an average depth of more than two miles. All
of this volume is a suitable habitat for life, so that the deep
oceans provide more than two hundred times more space for animals to
live than the space on all the land masses put together (Childress,
1983) . This means that most of the Earth's creatures live in an
environment so different from the one we experience that we can only
dimly imagine what life there might be like. Sunlight penetrates to
only a few hundred meters and seasonal changes do not penetrate very
deeply, so that most of the animals in the sea live in a world of
total darkness and constant temperature. There are no physical
boundaries between the surface and the bottom; all of the surfaces
in the deep ocean are produced by the organisms themselves. Since
the animals living in the water column are moving with the currents,
the midwater world appears motionless and free from turbulence.
Over the period that life has existed on Earth, the land masses have
changed and moved, but the ocean basins have always been in con-
tinuous connection with one another. Thus the deep sea has remained
the same, at least in a physical sense, for as long as it has
existed, although the organisms inhabiting it may have changed. I
say "may have changed", since there are very few fossil remains of

open ocean plankton, and thus we cannot know what the organisms
inhabiting the deep sea in Precambrian times were like. We can be
fairly certain, however, that the physical structure of the deep
ocean was much the same then as today. This largest, most constant,
and most alien (to us) of all the different environments on Earth is
also the most poorly understood.

It is difficult for a scientist to talk about the things he
does not know, and how necessary it is that we continue to explore,
since science is expressed in terms of what is known. This leads to
the general impression that a great deal is known. But a comparison
of the kinds of things we know about animals living in the open sea
with the kinds of things we know about animals living on land re-
veals the ignorance of those of us in plankton biology. We know
virtually nothing about the way midwater organisms live — how they
capture prey, avoid predators, find mates, how long they live,
whether they have courtship rituals or other social interactions,
and all the other sorts of information that makes terrestrial bio-
logy so interesting. We need to try to learn these details about
the lives of midwater organisms simply because the deep ocean is so
different from the environments that we are familiar with that it is
the best comparative system we have until life is discovered on
another planet. A better understanding of how animals live in
midwater cannot help but teach us more about how animals live in
general, and how they interact with their environment. For example,
we take it for granted that animals should be opaque, with strong
skeletal supports, but many of the organisms living in midwater are
transparent, with gelatinous bodies and long tentacles. This leads
us to see that terrestrial animals are constructed the way they are
to deal with intense solar radiation and the effects of gravity on
bodies unsupported by water, two physical constraints that are
missing in the deep sea. Yet some plankton ecologists have proposed
the very opposite, saying that midwater animals are transparent to
avoid predators, and flimsily-constructed because food is so scarce
(see Marshall, 1971) . How then to explain "extraneous" pigment
spots on otherwise transparent animals (Figs. 1 and 2)? How then
can we explain the fact that diaphanous jellies are parasitized by
much more substantial crustaceans (Madin and Harbison, 1977;
Harbison et al., 1977)? A recognition of past misconceptions points
up the fact that we need to free our thinking from its land-based
biases, and enter the deep ocean environment and look around.

I have been working on a heterogeneous group of animals
gelatinous zooplankton — for the past fifteen years. Most of my
work has been with SCUBA, in the upper 3 0 meters of the open sea.
In 1975, I had my first dive in a submersible, the DSRV ALVIN (Woods
Hole Oceanographic Institution) , to look at animals in midwater.
Since then, I have used the ALVIN on other occasions, the DSRV
JOHNSON-SEA-LINK (Harbor Branch Oceanographic Institution) and the
WASP diving suit (Oceaneering) for a total of over 1000 hours obser-
ving gelatinous animals in their natural environment.

Gelatinous plankton comprise a large, generally unrelated group
of organisms whose body tissues are mostly water. This group
includes colonial radiolarians, jellyfish, siphonophores,
ctenophores, pteropods, salps, doliolids, and even some fish and

Figure 1. The solitary salp, Ihlea punctata, has three bands of
pigment spots surrounding the body. At night, the spots contract
(a, b) , and during the day they expand (c) . These chromatophores
make this otherwise transparent animal much more conspicuous, and
undoubtedly serve to attract or repel some animal with image-forming
eyes. All photos are of the same animal, which is about 6 cm long.

Figure 2. Examples of conspicuous pigmentation in salps: (a) The
eight aggregate Ritteriella amboinesis (each about 2 cm long) are
barely visible, but the yellow "tail" makes them stand out. (b) The
solitary Traustedtia multitentaculata has two "tails," while (c) the
aggregates are covered with yellow spots as well. Fifteen
aggregates are in Fig. 2c, each about the same size as the solitary
(ca 1.5 cm) .

squids. Although there are gelatinous organisms living in lakes and
near the shore, it is the open sea where these animals attain their
greatest abundance and diversity. Because of their fragility, they
do not take well to areas with much mechanical stress, so most of
the names I have listed are unfamiliar, even to biologists. Yet
these exotic animals are among the most abundant large animals on
Earth, and are exotic only because one must go to sea in order to
study them.

The first tools that were used to study life in the open sea
were towed nets, and the towed net is still the most popular
collecting device today among plankton biologists. Although nets
can give a great deal of information, especially about organisms
that are rugged enough to withstand mechanical stresses, they do not
work very well with the gelatinous forms. To give an example, in
May 1983, I had the opportunity to use the JOHNSON-SEA-LINK to
collect ctenophores. On a single 10-day cruise in the Bahamas, I
collected nine different species of ctenophores, living at a depth
of 2000 ft — one species had not been reported since its original
description, two species had been previously described from the deep
sea by L. P. Madin and myself, and five were altogether new (two of
these new species are new genera) . During this cruise to one small
area in the North Atlantic, the known deep-sea ctenophore fauna was
doubled! Based on these collections, I have come to the belief that
most ctenophores are probably inhabitants of the deep ocean, and are
yet to be described.

As far as ctenophores are concerned (and probably a number of
other gelatinous animals as well) , plankton ecology is entering a
period resembling that of the early Nineteenth Century. As we
explore the deep sea for the first time, we encounter a fauna whose
presence was previously unknown (Fig. 3, for example). Our first
task is to describe the diversity of life we encounter, so that we
can move on to the science of the Twentieth and Twenty-first
Centuries. For other animals, which have been collected with nets,
there has been little progress since the latter part of the
Nineteenth Century, because the nets that are used today, though
considerably improved with sophisticated electronic devices, are
still essentially the same as the gear used a century ago. The data
are better, and there is a lot more environmental information, but
the questions are still the same as those posed by Nineteenth
Century plankton biologists (see Haeckel, 1893; Murray and Hjort,
1912) . Areas of research that have remained essentially unchanged
after more than a century are such topics as the vertical
distribution of the plankton, the relationship of faunal composition
to water masses, plankton patchiness, and the significance of the
co-occurrence of various species in net collections. Field
observations, directed sampling, field experiments and, above all,
the study of the behavior of undisturbed animals in their own
environment, all of which have radically changed the nature of
terrestrial ecology, are just beginning to have an effect on the way
plankton biologists think about their field.

Since collecting with towed nets gives little information about
what the animals were doing prior to capture, most plankton
biologists are concerned with only the grossest aspects of behavior
(such as relating distributions of animals to temperature or food
abundance, or inferring feeding strategies from analysis of gut

contents) . Others try to reconstruct behavior in the field from
morphology and laboratory studies on those few animals hardy enough
to survive the net collection. A good analogy that might be used to
see the pitfalls in this approach is to imagine what an ecological
study on hummingbirds might be like if the sole means of studying
them were with nets towed from helicopters. First, since few hum-
mingbirds could be collected in such a way, obtaining statistically
significant counts would be difficult. Very few would be collected
in association with flowers, and the only recognizable material in
their stomachs would be insects, since the nectar could easily be
undetected. If some animals survived the collection technique, it

Figure 3. An animal photographed at about 600 m off San Diego,
California by the Edgerton camera of the DSRV ALVIN. Each
photograph is taken at 4-second intervals. This animal, about the
size of a basketball, could be the jellyfish Deepstaria enigmatica
Russell. When first seen, it resembled a lampshade, and
when it encountered the turbulence from the submersible, it pursed
its lower end, and a peristaltic wave of contraction moved up the
body. Note the five "hooks" hanging in the center of the animal,
and that there is no trace of tentacles on the margins of the bell.
It is extremely difficult to imagine how this animal captures prey
in midwater.

might be possible to feed them insects in the lab, and measure their
growth and metabolism, constucting a very plausible scenario about
how they live without any reference to flowers! Of course, we know
that such a scenario is absurd, and the reason we know this is that
we can directly observe both hummingbirds and flowers. Direct
observation on planktonic animals is not so easy, so we probably
still have many absurd ideas about the way these animals live, based
on methods similar to those in the analogy above.

To cite a few examples, direct observation quickly established
that the picture previous plankton biologists drew of the lives of
shallow-living hyperiid amphipods, while plausible, was wrong.
These animals had been regarded as free-swimming zooplankton, but in
actuality they are parasites of gelatinous zooplankton (often quite
specific parasites) . A good case in point, directly comparable to
the "hummingbird" analogy, is that of the hyperiid amphipod,
Vibilia, a specific parasite on salps. This amphipod eats the food
string of its filter-feeding host, so that the material in its gut
is identical to the gut contents of a salp (Madin and Harbison,
1977) . If we did not know, from direct observation, the way Vibilia
lives, we could be easily misled into thinking that it was a free-
living filter-feeder. In the same way, other hyperiid amphipods,
which steal food from predatory gelatinous hosts, such as jellyfish
and siphonophores, were previously considered as free-living preda-
tors, until direct observation showed the true state of affairs
(Harbison et al., 1977). By observing them in the field, it was also
easy to see that shelled pteropods feed with external mucous webs,
and are neutrally buoyant in the water, contrary to earlier specula-
tions (Gilmer and Harbison, 1986) . I could give a number of other
examples as to the way that direct observation has changed our
conceptions about other zooplankton, such as copepods, medusae,
siphonophores, salps, colonial radiolarians, larvaceans, phyto-
plankton, and even marine snow. It should be noted that the first
(and until recently, best) reports on marine snow were based on
direct observations from a submersible (Nishizawa et al., 1954).

Hoping that I have convinced you that direct observation holds
the key to changing the very nature of plankton biology, or at the
very least provides vitally-needed information about how planktonic
animals live, the question remains, how do we go forward in
exploring deeper parts of the ocean?

At present, the JOHNSON-SEA-LINK (JSL) is the best submersible
for plankton studies. It has unrivalled visibility and superb
collecting devices. Its major limitations are that it is large, and
uses powerful lights in order to see the animals living in midwater.
It is obvious that both of these factors could disturb many midwater
creatures, but it is also likely that many animals will not be
affected very much at all. While we should continue to develop
methods to decrease the disturbance caused by our techniques of
observation, by using smaller submersibles, night -viewing devices,
etc. , we should continue to study those animals we can with existing
technology.

For the future, the direction is clear, and that is to spend
more and more time in the field, at greater and greater depths. As
I have stated previously (Harbison, 1983) , the ultimate goal is an
undersea research vessel that will allow biologists to spend all of
their time while at sea conducting in situ research. Such a vessel

could lock out divers and small submersibles for collecting, close-
up observations and directed sampling. We have spent enormous sums on
close-up investigations of other planets, and it is now time to think
about how we can also make close-up observations in the largest and
most alien place we have here on our own planet, the open sea.

ACKNOWLEDGEMENTS

I thank Marsh Youngbluth for providing my first opportunity to
dive in the JOHNSON-SEA-LINK, and Ron Gilmer for photographic
assistance. Photo credits: Fig. la by L. Bibko; Figs. 2a, b, and c
by M. Jones. Research supported by NSF grants OCE77-22511 and
OCE82-9341 and the Australian Institute of Marine Science.

LITERATURE CITED

Childress, J.J. 1983. Oceanic biology: lost in space? In: P.G.

Brewer (ed.), Oceanography. The Present and Future, p. 127-

135. Springer-Verlag, New York.
Gilmer, R.W. and G.R. Harbison. 1986. Morphology and field

behavior of pteropod molluscs: feeding methods in the family

Cavoliniidae, Limacinidae and Peraclididae, (Gastropoda:

Thecosomata) . Mar. Biol. 91: 47-57.
Haeckel, E. 1893. Planktonic studies: a comparative investigation

of the importance and constitution of the pelagic fauna

and flora. Trans, by G. W. Field. U. S. Commission Fish

Fisheries Report of the Commissioner for 1889 - 1891.

17:565-641.
Harbison, G.R. 1983. The structure of planktonic communities. In:

P.G. Brewer (ed.), Oceanography, the Present and Future, p. 17-

33. Springer-Verlag, New York.
Harbison, G.R. , D.C. Biggs and L.P. Madin. 1977. The associations

of Amphipoda Hyperiidea with gelatinous zooplankton. II.

Associations with Cnidaria, Ctenophora and Radiolaria. Deep-

Sea Res. 24: 465-488.
Madin, L.P. and G.R. Harbison. 1977. The associations of

Amphipoda Hyperiidea with gelatinous zooplankton. I.

Associations with Salpidae. Deep-Sea Res. 24: 449-463.
Marshall, N.B. 1971. Animal ecology. In: P.J. Herring and M.R.

Clarke (eds.) Deep Oceans, p. 205-224. Praeger Publishers,

New York.
Murray, J. and J. Hjort. 1912. The Depths of the Ocean.

MacMillan & Co., London.
Nishizawa, S., M. Fukuda and N. Inoue. 1954. Photographic study

of suspended matter and plankton in the sea. Bull. Fac. Fish.

Hokkaido Univ. 5: 3 6-40.

NOAA Symp. Ser. for Undersea Res. 2(2), 1987 93

BIOLOGICAL AND TECHNICAL OBSERVATIONS OF HALIBUT LONGLINE GEAR

FROM A SUBMERSIBLE

William L. High

National Marine Fisheries Service

Northwest and Alaska Fisheries Center

7600 Sand Point Way, N.E.

Seattle, Washington 98115-0070

ABSTRACT

The submersible Nekton Gamma (1978, 1980, 1982) and Mermaid
II (1983) were used to conduct studies associated with halibut
longline gear in Alaska coastal waters. Several bait types were
tested for durability on hooks and attractiveness to fish.
Traditional "J" type hooks and newly introduced "circle" type
hooks were compared for catch and escape rates. Also, a wide
range of incidental observations on fish and crab behavior and
fish habitat were made. An initial review of the data has
produced the following results: a future report will include a
more comprehensive analysis. Less than 2 0% of herring bait
remained on hooks after 2 -hours while about 80% of octopus bait
remained. Salmon bait was superior to all others tested. Because
of rapid bait loss, half the halibut were hooked within the first
2-hours of soak and less than 10% of the catch were hooked after
6-hours of soak. Circle hooks were far superior to traditional
hooks partly because they permitted fewer fish to escape. Circle
hooks captured 60% more halibut, 13 0% more rockfish (Sebastes)
and 100% more miscellaneous species. Small synthetic plastic
floats placed near the baited hook to float it above bottom
dwelling predators did not provide sufficient buoyancy at fishing
depths .

INTRODUCTION

Catch per unit effort (CPUE) is one measure used to assess
resource condition and size. While it is a useful tool for
monitoring the Pacific coastal halibut fishery, it is recognized
that halibut demersal longline gear effectiveness is influenced by
such factors as how fishermen rig and set their gear, how the hook
types are baited and with what type of bait, how long the gear is
left on the bottom (soak) before it is retrieved, and other
parameters .

A submersible was chartered over several years by NOAA's
Office of Undersea Research (OUR) , and in cooperation with the
International Pacific Halibut Commission (IPHC) , the NMFS
conducted a series of experiments to learn more about halibut
longline gear (High, 1980) . Our objectives included:

1) A study of common baits used, their attractiveness and rate of
loss,

94
2)

3)
4)

a comparison of the catching and holding power of the
traditional "J" type hook and a newly introduced "circle"
type hook,

determining the effect of soak time,

in situ observations of fish and gear behavior, and

viewing the effectiveness of commercially made floats designed
to hold the gangion and baited hook off the sea floor.

METHODS

Operations over the four years were similar although
fishermen, some submersible crews, and investigators changed. Our
goal was to reach the demersal longline gear as quickly after it
was set as submersible launch and safety considerations allowed,
generally in 20 to 40 minutes. The gear was located by descending
adjacent to the buoyline or by tracking a self-contained battery-
powered acoustic transmitter attached to the groundline (Figure

1).

Investigators attempted to view each hook and voice record
its status on magnetic tape for later transfer to permanent data

LONGLINE FISHING SYSTEM (side view)

Flag and marker buoy

Anchor

Groundline

SEA FLOOR

Ganglion (leader with hook)

Figure 1. Schematic view of longline fishing system.

sheets. Reference numbers were attached to the groundline about
every 10 hooks. Upon reaching the end of the longline, the
submersible either retraced its trackline for short interval
observations or surfaced to allow additional soak time before
collecting the next data set.

Submersible Systems;

The submersible Nekton Gamma was leased in the years 1978,
1980 and 1982. Chartered commercial king crab fishing vessels F/V
Antares (1978) and F/V Gold N Cloud (1980, 1982) transported the
submersible on deck to dive sites. Launches and recoveries, using
deck-mounted hydraulic cranes, were made over the vessels' side.

During 1983, the submersible Mermaid II was supported by its
mothership, M/V Aloha which handled the submersible over its stern
on a large gantry. Although the M/V Aloha worked best because of
its permanent support status, both fishing vessels, each in excess
of 125 ft (38 m) , had ample open deck space for all operations
and they both had the additional advantage of routinely handling
king crab pots used during some underwater studies. Both Nekton
Gamma and Mermaid II operated to 1,000 ft (304 m) . However,
during portions of the cruises devoted to longline studies,
longline gear was generally observed on commercial fishing grounds
at depths less than 600 ft (183 m) .

Each submersible carried a single science observer in
addition to the pilot. The Nekton Gamma observer viewed the sea
floor and longline gear from either of two 4" (10 cm) diameter
flat ports located on the hull's side. Forward directed ports
were useless for viewing because of a permanent coating of
hydraulic fluid from leaking mechanical arm lines. The pilot's
view through numerous conning tower ports was essentially
independent of the scientists' view. Mermaid II, on the other
hand, utilized a forward directed 3 0" (76 cm) viewing hemisphere.
Both scientist and pilot lay side by side, sharing a wide view
forward and to each side.

Longline Gear;

Demersal longline fishing gear observed each study year from
different fishing vessels was similar since North Pacific U.S.
halibut gear has been fairly well standardized over many years.
The groundline was 9/32 inch (.6 cm) treated nylon. Three foot
long gangions (leaders) of No. 72 thread nylon were attached with
5 inch long (12.7 cm) gangion snaps to the groundline at about 12-
15 ft (3.6-4.6 m) intervals as the groundline was set over the
vessel's stern. Traditional "J" type hooks (Figure 2), Mustad
62831 were studied until 1983 when the newly introduced circle
hooks (Figure 2), Mustad 39965 ST-3 were included. Except for a
few traditional 250 fathom (458 m) groundline skates fished from
the R/V John N. Cobb in 1978 and the R/V Thor in 1982, all
observed gear was fished from the commercial snap gear longliners
F/V Crusader. F/V Tiffy and F/V China B. Bait size was selected
by the fishermen but type and sequence of set was prescribed by
the science team. Each hook was observed for appropriate data as

Use of brand name does not imply endorsement of the product.

the gear was retrieved. Halibut were
immediately upon landing and other species identified.

measured

Comparing Bait:

Most bait studies were carried out using the standard "J"
hook with test baits alternately placed along the groundline.
Although the method has limitations, including the possible
overlapping attractiveness of one bait type to the other, rapidly
changing bottom type with resulting change in abundance of fish
and predators impacted less with this method. Two baits, salmon
and octopus, were compared during 1983 on the more successful
circle type hook. Each bait in groups of 10 hooks were placed
alternately along a groundline (Finley, 1984) .

r°

-1

-2
-3
-4
-5
-6
-7
8

-9
-10 cm

CIRCLE TYPE
(Mustad 39965St-3)

TRADITIONAL "J" TYPE
(Mustad 6283)

Figure 2. Hook types compared for catch and escape.

RESULTS

Bait Loss:

Loss of bait from hooks with soak time varied widely between
bait types. Bait toughness, attractiveness, sea floor type and
type and abundance of predators all contributed to bait loss. Of
the baits tested, herring disappeared so rapidly it was difficult
to estimate the rate. If we assume, as other studies show (Skud
and Hamley, 1978) , bait loss from the gear setting process to be
low, then in general, 80 to 90% of herring baits were removed

(10 to 2 0% retained) within an hour by striking fish and the many
predators found on most bottom types. Salmon bait likewise was
aggressively attacked. Its tougher skin, fins and bones
contributed to a 60% retention rate after 1 hour and 4 0% after 2
hours.

Both Pacific gray cod and octopus baits remained on the hooks
for longer periods. Contributing to this retention was the
apparent lack of interest in the bait by invertebrates such as
snails, starfish, shrimp and crab. Herring and salmon baits by
contrast were commonly covered with feeding invertebrates. In
Frederick Sound, Alaska, in 1978, about 80% of the octopus baits
were present after nearly 3 hours in spite of the presence of many
predators. In 1983 near Sitka with many halibut present, 50% of
the octopus baits remained in the same time period.

Because of the rapid loss of bait, half the halibut observed
hooked during 1983 dives were taken within the first 2 hours of
soak and less than 10% of the catch were hooked after 6 hours of
soak.

Bait Attraction:

Obviously some baits were more attractive than others to fish
and unwanted invertebrates. Bait loss rates reflect this as do
fish catch rates. Both salmon and herring baits, while on the
hook, caught more halibut than did either Pacific gray cod or
octopus. Few Pacific gray cod or octopus baits were observed
under attack by invertebrate predators.

Salmon bait was clearly superior to octopus when over 500
circle hooks having each of these baits were compared in alternate
groups of 10 baits along the groundline. Thirty-three percent of
those hooks with octopus bait had halibut as did 39% of salmon
baited hooks. Importantly, the difference in proportion of these
catches is 20% greater for salmon, a bait far less durable than
octopus .

Rockfish (mostly Sebastes ruberrimus) taken incidentally
during the salmon and octopus bait experiment occupied 15% of each
bait type hook, thus this species seemed to have no preference
between the two baits. Surprisingly, other species, mostly ling
cod (Ophiodon elongatus) occupied 1% and 2.8% respectively, of the
octopus and salmon baited hooks, a proportional increase for
salmon of 180%.

Comparing Circle and J Type Hooks:

Nearly 1,400 circle and J hooks were set alternately and
compared for catch. All baits (herring, salmon and octopus) and
soak times were combined. Results are shown in Table 1.

Halibut Escape from Hooks:

The submersible clearly was an excellent means to observe
escape of fish from hooks. Once observed hooked, the presence or
absence of a fish was confirmed on later dives or when the
appropriate hook was retrieved aboard the fishing vessel. Prior
to 1983, halibut escape rates from J hooks varied between 5 and
50% with an average of about 19%.

Table 1. Comparison of longline catch from 1,387 circle and
1,394 J type hooks.

Catch

% Increase

Circle

% Total

Catch

% Total

Proportion on

Species

Hook

C Hooks

J Hook

J Hooks

Circle Hooks

Halibut

256

18.5

157

11.3

63.7

Rockf ish

252

18.2

109

7.8

133.3

Other fish

2.2

1.1

100.0

Total Hooks
Occupied by
Fish 538

38.9

282

20.2

92.6

In 1983, nearly 1,400 circle and J type hooks were compared
for halibut escape. Of the 276 halibut which occupied circle
hooks, 20 (7.2%) escaped. Of the 1975 halibut which occupied J
hooks, 18 (10.3%) escaped. These escape rates although somewhat
lower than the average in prior years show the escape rate of
halibut to be 47% higher from J hooks than from circle hooks.
Obviously, this difference contributes to the overall better
performance of circle hooks.

Size of Fish by Hook Type;

Investigators, most of whom had scuba diving experience,
developed a moderate skill at estimating the size of halibut
viewed through the flat ports of Nekton Gamma. Initial efforts to
estimate halibut size through the large hemisphere port of Mermaid
II in 1983 were unsuccessful. Distortion caused fish to appear
much smaller than actual size.

Although we were not able to accurately estimate the size
of those which escaped from hooks in 1983, thereby learning if
escape was related to size, Steve Hoag, IPHC, was able to measure
all hooked halibut which came aboard the fishing vessel (Figure
3) . It appears somewhat smaller fish were taken by the circle
hook.

Incidental Observations:

Initially, at 200 to 500 ft depths, the commercially made
plastic gangion floats were not sufficiently buoyant to lift
either hook or bait above the sea floor. After several exposures
to these fishing depths, the floats lay useless on the bottom.

Hooked fish frequently had others of the same or different
species hovering nearby. Sometimes a rockf ish attempted to steal
the partially exposed hook or bait from a hooked fish and also
became hooked. This attraction to hooked fish may contribute to

80 r

DISTRIBUTION OF HALIBUT CATCH
by length for circle and J type hooks
alternately placed on groundline

Circle hook catch

55 75 95 115 135 155 175 195 +

Length of halibut (midpoint of 10 cm groups)

Figure 3. Distribution of halibut catch by length for circle and
"J" type hooks alternately placed on groundline.

the observation that halibut are not hooked randomly along the
groundline.

From time to time in each study year, halibut were
occasionally observed on hooks previously observed to be on the
sea floor without bait. We had no explanation but considered
errors in data collection were unlikely at the observed frequency.
Fortunately, in 1983 one investigator observed a halibut attack an
empty hook, thus becoming hooked.

Ken Parker, IPHC, documented on cine film most aspects of the
1983 research effort. From this footage, a descriptive 15 minute
sound film was produced by NOAA. Copies in 16 mm and VHS video
cassette formats are available from Camera One Productions,
Seattle, WA.

CONCLUSIONS

Herring is an adequate halibut bait only for very short

period soaks. Salmon bait is probably superior to all others

during soak times up to 3 hours. Octopus should be one of the
baits used when long soaks are necessary.

100

Circle hooks produce many more, although somewhat smaller
halibut. Some of this increase results from reduced escape from
the new hook. Since escape on both hooks is significant, the gear
should be retrieved when bait is mostly gone.

It is estimated that in the 6-month period after August 1983
when our preliminary study results on the circle hook performance
became generally known, more than 90% of the U.S. halibut longline
fishermen converted to the new hook in preparation for the 1984
spring fishing season.

Small commercially made plastic floats intended to lift the
baited hooks above the sea floor predators were not effective.

LITERATURE CITED

Finley, C. 1984. Halibut experiment finds circle hooks land more

fish. The Fisherman's News 40(4): 18.
High, W.L. 1980. Bait loss from halibut longline gear observed

from a submersible. Marine Fisheries Review 42(2): 26-29.
Skud, B.E., and J.M. Hamley. 1978. Factors affecting longline

catch and effort. I. General reviews, II. Hook spacing,

III, Bait loss and competition. Int. Pac. Halibut Comm. ,

Sci. Rept. 64,, 66 pp.

NOAA Symp. Ser. for Undersea Res. 2(2), 1987 101

LONG-TERM OBSERVATIONS ON THE BENTHIC BIOLOGY AND ECOLOGY
OF AN OFFSHORE DIVE SITE IN THE GULF OF MAINE

Ken Pecci
Northeast Fisheries Center Woods Hole Laboratory
Woods Hole, Massachusetts 02543

Alan Hulbert
National Undersea Research Program

University of North Carolina
Wilmington, North Carolina 28403

ABSTRACT

This paper presents the results from a long-term study of a
boreal hard bottom benthic community. The community population
structure was first described by disruptive collection of 0.25
m2 areas of benthic flora and fauna. Dominant species, analyzed
from photographs, were selected for long-term monitoring.
Population densities of ascidians, sea stars, and brachiopods have
been determined yearly from 1978 to 1983 by the use of in situ
photography. Ascidians have had a fluctuating population of 3 to
2 3/. 25 m2 , sea stars have increased from 4 to 39 and brachiopods
have decreased from 44 to less than 1.

INTRODUCTION

A program to monitor the health of the continental shelf
environment, namely the Northeast Monitoring Program (NEMP) , was
established by the National Marine Fisheries Service (NMFS) in
1978. This program used a variety of scientific disciplines to
assess the nature and extent to which our marine environment has
been or may be affected by pollution. As part of this program the
Manned Undersea Research and Technology (MURT) program of the
Northeast Fisheries Center (NEFC) began a research project in 1978
using in situ diving techniques to determine benchmark population
densities and pollutant body burdens of dominant macrobenthic
species at sites along the New England coast, on Georges Bank and
the Georges Bank submarine canyons (Figure 1) . The MURT sites
were complementary to the overall NEMP coverage and represent
areas difficult to sample with conventional surface techniques.
Nearshore hard bottom substrates, with attached flora and fauna
that can be most effectively studied and sampled in situ by divers
are the subject of this paper.

Pigeon Hill (Figure 1, Station 1) on Jeffreys Ledge in the
western Gulf of Maine was selected as a study area for its
pristine nature, accessibility by scuba, and background of study.
The biology and geology of Jeffreys Ledge (major herring spawning
grounds) has been a subject of study by us and other scientists
since 1971. Surveys of herring spawning areas there have been
discussed by Cooper et al. (1975) and the biology and geology by
McCarthy et al. (1979), Sears and Cooper (1978), Witman et al.
(1980), Pecci and Hulbert (1981), Hulbert et al. (1982), and
Witman and Cooper (1983) . Pigeon Hill is a hard substrate
undersea knoll at a depth of 33 meters with a complex community

102

- 45°

»Nft> J/

,2COU

GEORGES BANK

•5

'lydonia canyon

---^ *"——<%

H^_

j^s-''vCEANOGRAPHER CANYON

._«»*—

40°

Figure 1. Chart of the New England Continental Shelf showing
inshore and offshore Northeast Monitoring Program study sites
revisited annually by the NMFS dive team.

of flora and fauna typical of boreal benthic communities north of
Cape Cod, and because of its isolation the benthic community is
relatively unimpacted by pollution sources.

Three numerically dominant species are discussed, using long-
term (1978-83) population estimates: ascidians (Ascidia callosa) ,
sea stars (Henricia sanquinolenta) and the brachiopod
Terebratul ina septentrionalis . We will discuss a precipitous
decline in the density of Terebratul ina f a corresponding increase
in sea star density, and the association between brachiopods and
the encrusting sponge Iophon nigricans.

MATERIAL AND METHODS

We began the Pigeon Hill monitoring study by defining a
quantitative baseline of benthic inhabitants from in situ
photographic transects made from 1978 to 1983. With these

103

photographs we monitor the density of "indicator species" selected
for their numerical abundance, photographic affinities, and
trophic level. Information on the indicator species is then
considered as reflective of the dynamics within the ecosystem
(biotic and physical environments) (Paine, 1976; Hulbert 1980a,
1980b, 1981) . Additionally, indicator species were analyzed for
body burdens of heavy metals, petrogenic hydrocarbons, and
polychlorinated biphenyls.

The initial site descriptions were obtained from disruptive
collections of 0.25 m2 of ocean floor. Random 0.25 m2 quadrats on
both horizontal and vertical substrate surfaces were first
photographed, then disruptively sampled and subsequently re-
photographed. The work surfaces were scraped with a putty knife
and the organisms collected with an airlift into a 1-mm mesh bag,
brought to the surface, labeled and preserved. Subsequently
samples were sorted by species, and data on density,
size, and biomass were recorded.

Permanent transects 3 0 meters in length were established on
both horizontal and vertical surfaces at Pigeon Hill in 1978.
These sites have been revisited by scuba divers yearly for
rephotography of the benthic community by consecutive 0.25 m2
quadrats. From these photographs we derive counts of indicator
species and note changes in the ecological components of the
benthic community.

Sequential 0.25 m2 quadrats of bottom were photographed by
divers using a Nikonos underwater 35 mm camera equipped with a 15
mm lens. The camera is positioned 0.5 m off the bottom in an
aluminum frame, and records the area within a 0.5 m by 0.5 m
square. This non-destructive sampling allows resampling of sites
not disturbed by previous study.

RESULTS AND DISCUSSION

A total of 149 benthic species have been identified from the
Pigeon Hill disruptive samples. The species comprise two
ecologically distinct benthic communities: an algal-polychaete
community and a sponge-tunicate community. The local
distribution of the two major communities is determined by
substrate angle. The algal-polychaete community is dominant
horizontal rock surfaces and the sponge-tunicate community is
restricted to vertical rock walls.

The common species of the algal-polychaete community are the
red algae Ptilota serrata, the sabellid polychaete Chone
infundibuliformis and the terebellid polychaete Thelepus
cincinnatus. Ptilota averaged 66% coverage of horizontal
surfaces, and the mean densities of Chone and Thelepus were 254
and 164 individuals/0.25 m2 , respectively. Ptilota, Chone, and
Thelepus form an important three dimensional habitat providing a
secondary substrate on horizontal rock surfaces. Ptilota is an
upright algae with a branching form and both Chone and Thelepus
are tube dwellers that construct a matrix of tubes several
centimeters thick. The tubiculous amphipods Corophium
crassicorne. Ischvrocerus anquipes and Haploops tubicola also form

104

part of this tube matrix. A diverse invertebrate fauna inhabits
the tube matrix complex including amphipods, caprellids, small
asteroids, ophiuroids, brachiopods, and ectoprocts. Ophiuroids
are a common group associated with the horizontal surface
community; Qphiura robusta had a mean density of 447/0.25 m2 and
Qphioholis aculeata a density of 137/0.25 m2 . Crustose
coralline algae also occur on horizontal rock surfaces.

The vertical substrate is virtually free of sediment.
Ptilota is nearly absent from the sponge-tunicate dominated
vertical community. Crustose coralline algae are common on
vertical surfaces in conjunction with sponges, tunicates and
brachiopods. The sponge component of the community is represented
by at least nine species, although the actual number of species
that occur at Pigeon Hill is probably several times greater. The
sponge colonies have several major growth forms: (1) the thin,
sheetlike encrustations of Hymedesmia sp. and Halichondria
panicea, (2) the rounded globose form of Myxilla f imbricata.
Plocaminonida ambicrua and Iophon pattersoni, and (3) the upright
branching form of Haliclona palmata and Haliclona oculata. The
mean percent cover by sponges was 17.3% and tunicates covered 6%
of vertical surfaces. The tunicate fauna is represented by at
least seven species with the most common being Ascidia callosa.

In summary, the horizontal communities are dominated by
fleshy algae and a polychaete tube matrix which provide vertical
structure, secondary substrate and trap sediment. Vertical
communities are dominated by the colonial growth forms of sponges
and tunicates which trap little sediment and have few secondary
encrustations .

The long-term monitoring of indicator species by
rephotographing transects has been done for six years (1978-83) .
The abundances of the indicator species, asteroids (Asterias
vulgaris . Henricia sanquinolenta , Leptasterias sp., and
Stephanasterias albula) , ascidians (Ascidia callosa) , and
brachiopods (Terebratulina septemtr ional is ) , on our permanent
vertical transects are given in Table 1 and, on horizontal
transects in Table 2. Asteroid density increased between 1978 and
1981, then stabilized at about 40/O.25 m2 on vertical surfaces and
10-20/O.25 m2 on horizontal surfaces. The vertical surfaces
reflect a more accurate count of individuals present since the
absence of an algal mat aids in detectability. Ascidians, common
residents of vertical surfaces, had a fluctuation in population
but have ranged from 5-20/0.25 m2 with an increase in 1983 to
22/0.25 m2 . The 1983 increase was due to juveniles. Brachiopods,
dominant on vertical walls, continued to decline from a 1978 level
of 44.2 to 0.3/0.25 m2 in 1983 and are now nearly absent from the
permanent transects. There was less than 2% fleshy algal cover on
vertical transect surfaces, although coralline algae covered
significant amounts of area.

The densities of brachiopods and sea stars on the vertical
transects have had an inverse relationship throughout the period
of study (1978-83). Asteroids had an average density of 3.7/0.25
m2 in 1978, increased to 14.7 in 1979 and 37.6 in 1980, then
dropped in 1981 to 14.0 and rose to 38.9 in 1982 and 39.2 in 1983.
At the same time brachiopod densities demonstrated a steady
decline from 44.2 in 1978 to 0.3 in 1983.

105

Table 1. Abundance of indicator organisms from 0.2 5 m2
quantitative photographs along permanent transects on vertical
surfaces at Pigeon Hill.

Asteroids (#/.2 5 m2)

Date

S.D.

9/78

3.7

2.5

9/79

14.7

8.5

6/80

37.6

17.9

3/82

40.3

10.3

6/82

38.9

17.5

6/83

39.2

10.4

Ascidians

(Colonies/. 25

m2)

Date

S.D.

9/78

5.0

6.9

9/79

14.1

8.0

6/80

3.0

1.2

6/81

7.8

4.5

3/82

16.1

12.8

6/83

22.8

17,3

Brachiopods (#/.2 5 m2)

Date

S.D.

9/78

44.2

19.2

9/79

56.1

20.2

6/80

28.7

16.3

6/81

5.9

6.0

3/82

5.6

4.4

6/82

1.5

2.2

6/83

0.3

0.7

N
53
50
51
43
27
62

N
53
50
51
43
27
36
62

The reason, at least in part, for the precipitous decline in
the density of Terebratul ina is due to predation by sea stars.
Diver observations and in situ photographs confirm Terebratul ina
is a food source for asteroids. Asterias vulgaris was observed by
divers in a typical hunched feeding posture on a brachiopod at our
transect. Witman and Cooper (1983) state from their diving
observations and collections at Pigeon Hill, that cod (Gadus
morhua) and haddock (Melanogrammus aecrlef inus) were never observed
feeding on vertical rock wall benthos. They also conclude that
Terebratul ina living on rock walls were not affected by drilling
predators, but they did observe Leptasterias sp. feeding on
Terebratul ina . In view of these observations, combined with ours,
sea star predation may be the major cause of predator-induced
mortality of brachiopods at our study site.

Terebratul ina has one major epibiotic, the encrusting sponge
Iophon nigricans. Our initial survey in 1978 found 57% of

106

Table 2. Abundance of indicator organisms from 0.25 m2
quantitative photographs along permanent transects on horizontal
surfaces at Pigeon Hill.

Asteroids (#/.25 m2)

Date X S.D. N

9/78 0.6 0.9 55

9/79 2.1 1.8 61

6/80 4.6 3.2 60

6/81 10.8 4.5 68

9/81 27.0 9.9 26

3/82 19.7 7.5 34

6/82 13.5 7.3 64

6/83 10.7 4.6 63

Ascidians (Colonies/. 25 m2)

Date X S.D. N_

9/78 0.0 0.0 55

9/79 0.5 0.9 61

6/80 0.2 0.5 60

6/81 1.0 1.2 68

9/81 0.2 0.6 26

3/82 0.2 0.4 34

6/82 0.2 * 64

6/83 0.1 0.9 63

Brachiooods (#/.25 m2)

Date X S.D. N

9/78 3.0 3.0 55

9/79 4.7 5.9 61

6/80 3.7 3.6 60

6/81 0.4 1.1 68

9/81 0.5 0.8 26

3/82 0.4 1.0 34

6/82 0.3 0.7 64

6/83 0.0 0.1 63

Terebratul ina to be associated with Iophon. Encrusted and
nonencrusted individuals often resided adjacent to each other.
During our most recent survey (1983) , only 19 Terebratul ina
remained on the transect and, all were covered by sponge material.
This high observed proportion (X2 - test, P <0.01) of encrusted
individuals may be due in part to a protective advantage gained by
having epibiotic growth. Vance (1978) observed the shell of the
jewel box clam, Chama pellucida, to "normally be covered by a
dense growth of sessile plants and animals of phyla. Removal of
these epibionts seems to make detection and/or attack of Chama by
the predatory starfish Pisaster criqonteus more often successful in
the laboratory and substantially increases Chama mortality through
Pisaster predation in the field." Bloom (1975) found sponge

107

covering on scallop shells to be a protection from predatory
starfish by altering the surface texture of the shell and
decreasing the adhesive abilities of asteroid tube feet. We feel
the survival of the limited number of encrusted brachiopods at our
site may have also been due to the protective advantage of
sponge encrusting material.

CONCLUSIONS

Natural populations of marine organisms have two causes
of fluctuations in their densities: (1) the effect of their own
natural environment on reproduction and mortality and (2) man's
effect on their numbers either directly by harvesting or
indirectly by environmental changes such as temperature,
disruption of habitat or, the introduction of pollutants. To
assess the extent of population changes from man's influence, the
extent of changes from natural causes must be taken into account.
One purpose of this benchmark/monitoring study was to determine
this natural variability in a resident benthic population.

In our case there was an extensive decline in the brachiopod
population (probably from sea star predation) , a rise in sea star
density and a yearly variability in ascidian abundance. The
natural dynamics of this marine environment complicate the ability
to estimate the effects of man's influence over a long term, but,
if a yearly photo-survey is done, any immediate impact can be
determined.

LITERATURE CITED

Bloom, S.A. 1975. The motile escape response of a sessile prey:
a sponge-scallop mutualism. J. Exp. Mar. Biol. Ecol. 17:
311-321.

Cooper, R.A., J.R. Uzmann, R.A. Clifford, and K.J. Pecci.1975.
Direct observations of herring (Clupea harengus harenaus L. )
egg beds on Jeffreys Ledge, Gulf of Maine, in 1974. ICNAF
Res. Doc. 75/93.

Hulbert, A.W. 1980a. The ecological role of Asterias vulgaris in
three subtidal communities. In: M. Janquox (ed.),
Echinoderms: Past and Present. A. A. Balkema, Rotterdam.

Hulbert, A.W. 1980b. The functional role of Asterias vulgaris
Verrill (1866) in three subtidal communities. Ph.D. Thesis,
University of New Hampshire. 183 pp.

Hulbert, A.W. 1981. Size-limited predation by the northern
seastar, Asterias vulgaris. American Zoologist. 20(4).
Abstract.

Hulbert, A.W. , K.J. Pecci, J.D. Witman, L.G. Harris, J.R. Sears,
and R.A. Cooper. 1982. Ecosystem Definition and Community
Structure of the Macrobenthos of the NEMP Monitoring Station
at Pigeon Hill in the Gulf of Maine. NOAA Tech. Memo. NMFS-
F/NEC-14. 143 pp.

McCarthy, K. , C. Gross, R. Cooper, R. Langton, K. Pecci, and J.
Uzmann. 1979. Biology and Geology of Jeffreys Ledge and
Adjacent Basins: an Unpolluted Inshore Fishing Area, Gulf of
Maine. NW Atlantic. ICES, CM. 1979/E: 44. 12 pp.

108

Paine, R.T. 1976. Size-limited predation: An observational and
experimental approach with Mvtilus and Pisaster interaction.
Ecology 57(5): 858-873.

Pecci, K.J., and A.W. Hulbert. 1981. An interim report on the
Pigeon Hill dive site. Coastal Ocean Pollution Assessment
News 1(3) .

Sears, J.R., and R.A. Cooper. 1978. Descriptive ecology of
offshore, deepwater, benthic algae in the temperate western
North Atlantic Ocean. Marine Biology 44: 309-314.

Vance, R.R. 1978. A mutualistic interaction between a sessile
marine clam and its epibionts. Ecology, 59(4), pp. 679-685.

Witman, J.D., A.W. Hulbert, L.G. Harris, K.J. Pecci, K. McCarthy,
and R.A. Cooper. 1980. Community structure of the
macrobenthos of Pigeon Hill in the Gulf of Maine. University
of New Hampshire - National Marine Fisheries Service
Technical Report. ,Univ. New Hampshire, Durham, N.H. 83 pp.

Witman, J.D., and R.A. Cooper. 1983. Disturbance and contrasting
patterns of population structure in the brachiopod
Terebratul ina septemtr ional is (Couthouy) from two subtidal
habitats. J. Exp. Mar. Biol. Ecol. 73: 57-79.

NOAA Symp. Ser. for Undersea Res. 2(2), 1987 109

HABITAT AND BEHAVIOR OF JUVENILE PACIFIC ROCKFISH
fSEBASTES SPP. AND SEBASTOLOBUS ALASCANUS) OFF SOUTHEASTERN

ALASKA

Richard R. Straty
Northwest and Alaska Fisheries Center Auke Bay Laboratory
National Marine Fisheries Service, NOAA
Box 210155, Auke Bay, AK 99821

ABSTRACT

Nursery grounds of Pacific ocean perch (Sebastes alutus) off
Alaska must be located so that the feasibility of indexing their
abundance before recruitment to the fishery can be assessed.
Trawl catches of foreign fishing and U.S. research vessels on the
fishing grounds have contained only a few older juveniles (4- to
5-yr olds) and no 1- to 3-yr-old Pacific ocean perch; however,
small juveniles have been captured in a few coastal bays and
fiords of southeastern Alaska. Biologists have hypothesized that
the extremely uneven and virtually unsampled rocky bottom
between 20 and 80 fathoms is the nursery grounds for this species.
Because this area cannot be sampled by conventional fishing
methods, we used the submersibles Nekton Gamma and Mermaid II to
visually locate and sample juvenile rockfish and describe their
habitat and behavior. Large compact schools and solitary small
red rockfish (Scorpaenidae) were observed in 1978 and 1980. In
1983, five species of juvenile rockfish, including Pacific ocean
perch, were captured, identified, and aged. Juvenile rockfish,
particularly Pacific ocean perch and sharpchin rockfish (S.
z_acentrus) , sought refuge in crevices between rocks and along
the side of boulders when frightened. For this reason, juvenile
rockfish are difficult to sample by conventional methods, even in
areas with smooth bottom, which are amenable to trawling.

INTRODUCTION

During the 1960's and early 1970 's, Pacific ocean perch
(Sebastes alutus) made up most of the foreign groundfish catch in
the eastern Gulf of Alaska; however, by 1979, catches of Pacific
ocean perch had declined, and the stocks were considered to be
overfished (Ito, 1982) . The United States now prohibits foreign
trawling in the eastern Gulf of Alaska east of 140°W longitude so
that Pacific ocean perch stocks can rebuild and be profitably
harvested by U.S. fishermen.

Eliminating foreign fishing in the eastern Gulf of Alaska
also eliminated the main data base used by fishery managers to
monitor stock abundance. As a result, the National Marine
Fisheries Service now conducts triennial research trawl surveys in
this region. Catches of Pacific ocean perch in these surveys have
been mainly adults (6- to 8-yr-olds and older) . Four- and five-
year-old Pacific ocean perch are caught occasionally in catches of
U.S. research vessels and foreign trawlers; 1-to 3-yr-olds are

110

not. Subsequently, any effect of prohibiting foreign fishing on
the rebuilding of Pacific ocean perch stocks is not measurable
until a year class enters the adult population at 6-8 yr.

If the location of nursery grounds for Pacific ocean perch
were known and juveniles could be effectively sampled, trends in
stock abundance could be measured several years before the year
class is recruited to the fishery. Small juvenile Pacific ocean
perch have been captured in a few coastal bays and fiords in
southeastern Alaska over steep slopes and ledges near rocky areas
(Carlson and Haight, 1976) . The lack of juveniles in offshore
catches and their occurrence in catches in coastal bays and fiords
led these authors to hypothesize that the extremely uneven rocky
bottom areas nearer the coast than the area occupied by the adults
are nursery grounds for Pacific ocean perch. Juvenile demersal
fish inhabiting these areas have not been extensively sampled
because rugged bottom and strong tidal currents preclude
deployment of conventional fishing gear (e.g., trawls, traps, gill
nets) .

In 1978, Carlson and Straty (1981) used the two-man
submersible Nekton Gamma to visually search for young Pacific
ocean perch in two rocky-bottom coastal areas and in an adjacent
bay and strait protected from open-sea conditions in the northern
part of southeastern Alaska. They observed large schools of
"reddish rockfish" that they believed to be Pacific ocean perch;
however, they were unable to verify the identification.

In an extension of Carlson and Straty 's (1981) work, we used
the submersibles Nekton Gamma and Mermaid II to locate, observe,
and capture small juvenile red rockfish off the coast of
southeastern Alaska in 1980 and 1983. The primary objectives of
these surveys were to describe and photograph the habitat and
behavior of juvenile rockfish and secure specimens of them for
identification. Pacific ocean perch was the target of our
investigations because of its former commercial abundance and
potential value to U.S. fishermen. In this paper, I present our
observations of the habitat and behavior of young rockfish of
those species successfully captured and identified during the 1983
submersible survey and discuss some possible implications of this
new information.

METHODS

Fourteen locations off the coast of southeastern Alaska
between Cape Cross and Cape Muzon were surveyed with a submersible
in 1980 (Fig. 1) . Sixteen coastal locations in the same area were
surveyed in 1983. The selected coastal sites had the type of
habitat where Carlson and Straty (1981) observed large
concentrations of small juvenile red rockfish. In addition, two
bays on the east side near the southern tip of Baranof Island were
surveyed in 1983. Juvenile Pacific ocean perch were captured by
trawl in these bays by Carlson and Haight (1976) . Depth of the
survey sites ranged between 37 and 223 m. Sites with hard bottoms
ranging from almost flat to extremely steep with frequent changes
in relief (Fig. 2) were preferred.

Ill

0 20 no

1 1 1 1 1

MILES

•

1980 SURVEY LOCATIONS
1983 SURVEY LOCATIONS

ALASKA

J CANADA

«^

..>

f SURVEY
1

'AREA

CAPE MUZON

INDEX MAP

135c

133

131

-b

Figure 1. Location of submersible surveys for juvenile rockfish
off southeastern Alaska, August 1980 and 1983.

112

Observations of juvenile rockfish behavior and habitat at
each location were recorded on 35-mm colored film and on color
video tape. A 35-mm camera and attached synchronized strobe light
(1980 and 1983) and video camera (1983) were externally mounted on
the submersibles. In addition, a hand-held 16-mm movie camera was
used from inside the Mermaid II in 1983 to record observations in
color taken through the forward port.

Figure 2 . Typical bottom topography of areas surveyed for
juvenile rockfish off southeastern Alaska, August 1980 and 1983.

113

In 1980, we unsuccessfully tried to collect small juvenile
rockfish with baited minnow traps and small variable-mesh
monofilament nylon gill nets deployed from the submersible. In
1983, we used an electric motor- and pump-driven slurp gun (Fig.
3) and a sedative to capture juvenile rockfish. The slurp gun,
attached to the left manipulator of the Mermaid II, was fabricated
from 13-cm diameter aluminum pipe open at one end and was fitted
at the other end with a 0.64-cm mesh net collecting bag. Suction
at the open end of the pipe was created when water was pumped
under pressure (60 gal/min [227 1/min] at 80 lb/ in.2 [5.6 kg/cm2])
through the pipe toward the net bag. Water was pumped to the
pipe through 2 . 5-cm plastic hose by a vane pump attached near the

Figure 3. Slurp gun attached to the manipulator of submersible
Mermaid l£ and used to capture juvenile rockfish off southeastern
Alaska, August 1983.

114

stern of the submersible and driven by a 7-hp electric motor.
When the batteries of the submersible were fully charged, the
suction created at the open end of the slurp gun by this venturi
design was sufficient to capture small (<60 mm in length) sedated
fish at a distance of 30 cm. At closer distances, fish up to 20
cm could be captured. The sedative, quinaldine (2-
methylquinoline) , was placed in an air-charged scuba bottle and
was dispensed into the water through a plastic hose connected to a
nozzle attached to the same manipulator as the slurp gun.
Quinaldine was premixed with ethyl alcohol to give a 20%
quinaldine solution. Fish exposed to this concentration became
sedated within 15-30 s; however, bottom currents and buoyancy of
quinaldine solution made it difficult to expose fish for this
time. In most instances, juvenile rockfish were collected with
the slurp gun without the quinaldine solution.

RESULTS
Collection and species identification of juvenile rockfish

We were unable to collect juvenile rockfish in 1980 with the
baited minnow traps and variable-mesh gill nets because juvenile
rockfish, although present in large numbers, were driven off when
adult rockfish appeared. These large fish, apparently attracted
by the plankton, bait in the minnow traps and the noise and lights
of the submersible, attacked the traps to get at the bait. This
disturbance kept small rockfish away. Large rockfish also became
entangled in the small-mesh gill nets and created a disturbance
that again kept small rockfish away.

In 1983, 83 juvenile red rockfish of five species were
captured with the slurp gun at 12 of the 16 locations surveyed by
submersible off the outer coast of Baranof and Chichagof Islands
(Fig. 1) . These rockfish represent only a fraction of the total
number of juvenile red rockfish observed during the surveys, and
most are species that sought refuge between or near rocks
when alarmed by the movement of the submersible and slurp gun. We
were unable to capture juvenile red rockfish that were in large
schools above the substrate, near the upper slopes of rocky
pinnacles and over them (see Figs. 5, 6, 9, and 11 of Carlson and
Straty, 1981) . Some method of dispensing a directed jet of large
quantities of quinaldine a distance of >1 m from the submersible
could probably be used to sedate these fish so they could be
captured with the slurp gun.

Juvenile rockfish collected in our studies were identified
from counts of anal, pectoral, and soft dorsal fin rays, gill
rakers, lateral-line scales or pores, scale rows below the lateral
line, the presence or absence of an extra head spine, and the
length of the second anal-fin spine. All juvenile rockfish were
measured (standard and fork lengths) , and the age of most species
was determined from otoliths and scales (Table 1) . Otolith ages
were determined by the "break-and-burn" technique (Chilton and
Beamish, 1982) .

115

Table 1. Age, size and depth of occurrence of juvenile rockfish,
Sebastes spp. and Sebastolobus sp. , captured during submersible
surveys off southeastern Alaska, 5-13 August, 1983. Ages of
shortspine thornyheads were estimated from length-age
relationships (P. Miller, NMFS Auke Bay Laboratory, pers. comm.
1984) .

Species

Age in
years

Number
at each
age

Range
in fork
length

(mm)

Depth
range of
capture
(m)

1
2
3

1
2
2

78
104-115
151-164

146-149

134
146-171

1
2
3
4
5

12
9
4
2
2

44-75

83-106

141-170

176-197

205-206

116-171
116-131
134-149
143-171
171

1
2
3

12
14
13

47-81
81-120
125-173

81-143
81-143
85-143

1
2

70-89
121

81
81

1
3
5
7
11

1
1
2
1
2

110
134-150

174
220-226

222
171
222
171
171-222

Pacific ocean perch,
(Sebastes alutus)

Sharpchin rockfish,
(Sebastes zacentrus)

Pygmy rockfish,
(Sebastes wilsoni)

Puget Sound rockfish,
(Sebastes emphaeus)

Shortspine thornyhead,
( Sebastolobus alascanus)

Unidentified Sebastes sp,

106

115

Juvenile Pacific ocean perch and sharpchin rockfish Sebastes
zacentrus were captured at similar depths (Table 1) in similar
habitat (Fig. 4) . Both species have barred blotches on the back
and upper lateral surfaces. This marking generally extends below
the lateral line of juvenile sharpchin rockfish but not below the
lateral line of juvenile Pacific ocean perch (Fig. 5) . The
consistency of this difference, however, cannot be determined
without examination of many specimens collected from various parts
of the range of the two species. If consistent, the difference in
color pattern could be used to identify these species visually
from a submersible and from photographs.

116

Juvenile pygmy rockfish, Sebastes wilsoni. which were more
prevalent at shallower depths than juvenile Pacific ocean perch
and sharpchin rockfish (Table 1) , have less distinct blotches than
sharpchin rockfish and Pacific ocean perch. Furthermore, pygmy
rockfish have a reddish back and white belly, coloration
sufficiently different from juvenile Pacific ocean perch and
sharpchin rockfish to distinguish between these species from the
submersible even though the identity of pygmy rockfish was not
known when collected.

Figure 4. Juvenile Pacific ocean perch or sharpchin rockfish in
typical habitat off southeastern Alaska, August, 1983.

One Puget Sound rockfish, Sebastes emphaeus, was positively
identified and two were tentatively identified. Puget Sound
rockfish were captured at the shallowest location surveyed (Table
1) . Juvenile shortspine thornyheads, Sebastolobus alascanus,
could be easily identified from the submersible (Fig. 6) . They
lack the barred blotches of juvenile Pacific ocean perch,
sharpchin rockfish, and pygmy rockfish and have the distinctive
shape and dark-orange uniform coloration of the adults.

117

3 POP

3SH

•::nmtfA

AQ12P0P

" • • ■:--JS::jjj::;:::::::::::

D/V£ 3C|

S&L 1 POP

,v/a*Jv.v.v.v

Figure 5. Three juvenile Pacific ocean perch (POP) age 1, 2, and
3 years and an age-3 sharpchin rockfish (SH) captured with a
submersible slurp gun off southeastern Alaska, August 1983.

The color of the blotches on juvenile rockfish changed
between the time they were captured with the slurp gun and the
time they were later examined on the surface. The change was
particularly noticeable in juvenile Pacific ocean perch and
sharpchin rockfish. When observed from the submersible, the
barred blotches on the back and upper lateral surfaces of these
species appeared to be made up of alternating dark and almost
white markings (Figs. 4, 7 and 8) . When examined later on the
surface, the white markings had changed to the reddish-orange of
the rest of the body. This change was so striking, it was
difficult to believe we were looking at the same fish we had
collected.

118

■ - ' 1 1 1 H i

lLfl|Sa

■

■ h "■■- mm 1 " 1 J

- . ■ i

■

Kki w

(

Bj^Hf

L ***

■

Figure 6 . Juvenile shortspine thornyhead seeking refuge near a
boulder off southeastern Alaska, August 1983.

The ability to change color quickly was observed in situ when
an apparently alarmed juvenile red rockfish changed color on its
back from a uniform to a barred blotched pattern. This
observation was made at the shallowest depths surveyed (81 m) and
would exclude Pacific ocean perch and sharpchin rockfish as the
likely species observed.

Depth distribution and age of juvenile rockfish

With the exception of the shortspine thornyheads, most
juvenile rockfish were 1- to 3-yr-old (Table 1) . Larger,
presumably older juvenile red rockfish with the coloration pattern
of those captured were observed and photographed but were too
elusive to be captured with the slurp gun. Too few juvenile

119

Figure 7. Juvenile Pacific ocean perch or sharpchin rockfish
seeking refuge between boulders off southeastern Alaska, August
1983.

Figure 8. Juvenile Pacific ocean perch or sharpchin rockfish
seeking refuge near a cobble off southeastern Alaska, August 1983.

120

rockfish of each species were collected to show a depth preference
by age. Shortspine thornyheads had the deepest distribution, and
the pygmy rockfish and Puget Sound rockfish had the shallowest
distribution (Table 1) . Pacific ocean perch and sharpchin
rockfish had an intermediate and similar depth distribution.

Habitat and behavior of juvenile rockfish

The 1- to 3-yr-old Pacific ocean perch and 1- to 5-yr old
sharpchin rockfish were observed and captured in similar habitat.
Individuals or groups of two to three fish separated by 0.5-1.0 m
or more were observed over bare to lightly silt-covered cobble
(64-256 mm in diameter) interspersed with frequent boulders (256
mm and larger) (Figs. 4, 7 , 8) . The shallower habitat of 1- to 3-
yr-old pygmy rockfish and Puget Sound rockfish was also bare or
lightly silt-covered but contained more large boulders,
boulder piles and solid rock outcrops. The habitat of 1- to 11-
yr-old shortspine thornyheads captured at the deepest locations
(Table 1) was bare to lightly silt-covered cobble (64-256 mm in
diameter) with fewer large boulders than the habitats of other
species of juvenile rockfish (Fig. 6) (shortspine thornyheads at
Cape Ommaney mature between age 6 and 13; P. Miller, NMFS Auke Bay
Laboratory, M.S. Thesis, in preparation) . Individual or groups of
two or three juvenile shortspine thornyheads separated by 0.5 m or
more were captured in areas with few abrupt changes in bottom
relief and no solid rock outcrops.

Juvenile red rockfish were observed in areas having stands of
large white anemones, Metridium senile, on the upper slopes and
tops of rock outcrops or pinnacles at depths <171 m (see Fig. 11
in Carlson and Straty, 1981). In 1983, we collected pygmy
rockfish and Puget Sound rockfish from this type of habitat but no
juvenile Pacific ocean perch, sharpchin rockfish, or shortspine
thornyheads .

Small juvenile Pacific ocean perch, sharpchin rockfish, pygmy
rockfish, and shortspine thornyheads sought refuge in the spaces
between and along the side of cobbles and rocks when alarmed by
movement of the submersible and slurp gun (Figs. 7 and 8) . They
placed one side against a cobble or boulder, assumed the curvature
of the rock (Figs. 6 and 8) , then ceased moving (species
verification based on colored video tape recordings of captured
fish, which were later identified) . This behavior made these
rockfish easier to capture with the slurp gun than continuously
moving species in large schools 0.5-1 m or more above the
substrate (see Figs. 5, 6, 9 and 11 of Carlson and Straty, 1981) .

DISCUSSION

The barred blotches of 1- to 3-yr-old Pacific ocean perch and
their behavior of remaining near or in frequent contact with the
substrate casts doubt on speculation by Carlson and Straty (1981)
that the "clouds of 6-8 cm reddish rockfish" they observed near
and on the top of rocky pinnacles are juvenile Pacific ocean
perch. We observed many similar schools of small reddish rockfish

121

in the same habitat during the 1980 and 1983 submersible surveys.
In colored photographs taken of these schools in 1978, 1980, and
1983 during submersible surveys, the small rockfish either lacked
the prominent barred blotches of juvenile Pacific ocean perch and
sharpchin rockfish or the blotches were much less prominent.
Photographs taken in 1978 at depths deeper than areas where these
large schools were found had small rockfish with the prominent
barred blotches characteristic of Pacific ocean perch and
sharpchin rockfish, and the habitat was the same as the habitat
where we found Pacific ocean perch and sharpchin rockfish in
1983.

Habitat of 1- to 3-yr-old Pacific ocean perch off the outer
coast of southeastern Alaska recorded in the submersible surveys
is markedly different from the habitat described and photographed
for this species inside several adjacent coastal bays and fiords
(Carlson and Haight, 1976) : the substrate off the coast has less
silt cover and many more cobbles and large boulders. The
substrate inside coastal bays has many shell fragments, whereas
none were observed in photographs and colored video recordings of
the substrate at offshore locations.

Two of the bays surveyed with a bottom trawl by Carlson and
Haight (1976) , Big Port Walter and Port Conclusion, near the
southern tip of Baranof Island (Fig. 1) , were surveyed by
submersible in 1983. We were unable to capture juvenile rockfish
in these bays although some were observed that had the appearance
of Pacific ocean perch or sharpchin rockfish. The fish were not
nearly as abundant in these bays as at offshore locations possibly
because of differences in substrate composition between offshore
and bay locations. The cobble and boulders noted at offshore
locations and resulting spaces between them probably offered more
refuge than substrate inside bays.

Although more small juvenile rockfish were observed offshore
than inside the bays, the offshore locations did not appear to
have nearly as many fish as could be accommodated by the amount of
refuge between boulders and cobbles. If available refuge is a
factor limiting the abundance of small juvenile rockfish in an
area, the offshore areas surveyed appeared to be underutilized and
may reflect the present low abundance of Pacific ocean perch off
southeastern Alaska.

Differences in the substrate composition between bays and
offshore locations, the behavior of 1- to 3-yr-old Pacific ocean
perch when alarmed, and the types of fishing gear used by
commercial and research fishing vessels to capture adult and
juvenile perch may explain why small juvenile Pacific ocean perch
have only been previously captured inside bays and not offshore.
Off the coast of southeastern Alaska, bottom trawls of foreign
commercial fishing and U.S. research vessels are fitted with
rubber rollers to keep the net off bottom and avoid snagging it on
frequent large boulders. Trawls used by U.S. research vessels
engaged in sampling groundfish off the coast of southeastern
Alaska use 14-in. (36 cm) diameter rollers in the wings and 18-in.
(46 cm) diameter rollers in the middle of the net (Fred Wathne,
NMFS Laboratory, Seattle, Washington, pers. commun. 1984) . The
bottom of the trawl entrance is 7-9 in. (18-23 cm) , off the

122

bottom. Foreign trawlers previously fishing for Pacific ocean
perch off southeastern Alaska used larger nets and rollers than
U.S. fishing vessles. The behavior of 1- to 3-yr-old Pacific
ocean perch and other juvenile rockfish species when alarmed keeps
them close to the bottom, well below the entrance to these trawls.
Carlson and Haight (1976) did not use rubber rollers on trawls
used to sample fish inside bays in 1976 (H.R. Carlson, NMFS Auke
Bay Labaoratory , pers. commun. 1984) . The entrance of the trawl
thus remained on a bottom that had fewer cobbles and boulders than
the bottom offshore; thus, more small juvenile Pacific ocean perch
could be captured. The trawls used by these authors also had
smaller mesh, which retain more small fish than trawls fished
offshore.

Because large juvenile and adult Pacific ocean perch,
sharpchin rockfish, and shortspine thornyheads off the coast of
southeastern Alaska are caught in trawls, these species probably
venture farther above the bottom with increasing age and size, as
our observations and photographs show. Larger juvenile rockfish
in the same habitat as small juveniles would also be more
vulnerable to capture by trawls with rollers than small juveniles.

Although adult Pacific ocean perch form schools (see Major
and Shippen, 1970) , 1- to 3-yr-old Pacific ocean perch apparently
do not form schools as Carlson and Haight implied (1976) .
Individual or loose aggregations of juveniles were observed in
close contact with the bottom and separated by >0.5 m, rather than
in schools. Pacific ocean perch and probably sharpchin rockfish
and other Sebastes spp. whose juveniles have a distribution
similar to Pacific ocean perch probably form larger, more compact
schools with increasing age and size.

Although only a few of each species of 1- to 3-yr-old
juvenile rockfish were captured during submersible surveys, many
more of the same size, coloration, and behavior, and in the same
or similar habitats were observed and documented on colored, video
tape and 35-mm film. This type of information could have only
been obtained with a manned, maneuverable underwater vehicle in
regions like those off the coast of southeastern Alaska. Although
the offshore areas appear to be more important than bays as
nursery grounds for 1- to 3-yr-old Pacific ocean perch and other
rockfish species, it is unlikely that offshore areas can be
effectively and economically sampled by present fishing
techniques. Trawl sampling of these age groups in coastal bays
over smoother bottom may provide the only effective means of
measuring trends in the abundance of Pacific ocean perch during
the early juvenile stage of their life history.

ACKNOWLEDGEMENTS

The author gratefully acknowledges the contributions made to
this study by the following individuals: Robert Budke, Fishery
Technician at the NMFS Auke Bay Laboratory, served as an observer
aboard the submersible Mermaid II and assisted in all aspects of
the study; Alex Peden, Curator of Aquatic Zoology at the British
Columbia Provincial Museum in Victoria, British Columbia, Canada,

123

also served as an observer aboard Mermaid II and identified the
species of juvenile rockfish collected; Richard Rosenthal,
Cinematographer/Marine Biologist, served as an observer aboard
Mermaid II and provided excellent colored 16-mm movies of marine
life observed during surveys; H. Richard Carlson, Fishery
Biologist at the Auke Bay Laboratory, provided the age
determinations for juvenile rockfish collected, and Patricia
Miller, Technical Publications Editor at the Auke Bay Laboratory,
provided information on the age of shortspine thornyheads from her
thesis on this species.

Special thanks are due to Booker T. Washington and his
support crew and pilots of Mermaid II for fabrication and
successful operation of the slurp gun and their extra efforts to
ensure maximum use of the submersible during the time allotted for
this study. Finally, I am deeply indebted to NOAA's Office of
Undersea Research (OUR) in Rockville, Maryland, for making
submersibles available in 1978, 1980, and 1983 to conduct this
study .

LITERATURE CITED

Carlson, H.R., and R.E. Haight. 1976. Juvenile life of Pacific
ocean perch, Sebastes alutus, in coastal fiords of
southeastern Alaska: their environment, growth, food
habits, and schooling behavior. Trans. Am. Fish. Soc. 105:
191-201.

Carlson, H.R. , and R.R. Straty. 1981. Habitat and nursery
grounds of Pacific rockfish, Sebastes spp. , in rocky coastal
areas of southeastern Alaska. Mar. Fish. Rev. 43(7): 13-19.

Chilton, D.E., and R.J. Beamish. 1982. Age determination methods
for fish studies by the groundfish program at the Pacific
Biological Station. Can. Spec. Publ. Fish. Aquat. Sci. 60,
102 pp.

Ito, D.H. 1982. A cohort analysis of Pacific ocean perch stocks
from the gulf of Alaska and Bering Sea regions. M.S. thesis,
Univ. Washington, Seattle, Wash., 157 pp.

Major, R.L., and H.H. Shippen. 1970. Synopsis of biological
data on Pacific ocean perch, Sebastodes alutus. FAO Species
Synopsis No. 79. U.S. Dep. of Commer. , Natl. Mar. Fish.
Serv. Circular 3 47, 3 8 pp.

CHAPTER III

POLLUTION

NOAA Symp. Ser. for Undersea Res. 2(2), 1987 127

LEVELS OF HEAVY METALS, PETROGENIC HYDROCARBONS,
AND POLYCHLORINATED BIPHENYLS IN SELECTED MARINE SAMPLES

FROM THE NEW ENGLAND COAST

K.J. Pecci
Northeast Fisheries Center Woods Hole Laboratory
National Marine Fisheries Service, NOAA
Woods Hole, Massachusetts 02543

ABSTRACT

The levels of seven heavy metals (Ba, Cr, Cd, Pb, Hg, Zn) ,
petrogenic hydrocarbons, and polychlorinated biphenyls were
determined for two marine algae, eight marine animals, and
sediment collected in situ during 1980 and 1981. Faunal samples
were taken of prominent endemic species at eight sites.
Collection areas were: Northern New England coast, Southern New
England coast, Georges Bank, and Georges Bank submarine canyons.

This report presents the results from sample analyses.
Levels of metals were within expected ranges, although particular
organs or particular specimens seemed to concentrate certain
metals. Petrogenic hydrocarbons and polychlorinated biphenyls
were at very low levels or nonexistent.

INTRODUCTION

A program to monitor the health of the coastal marine
environment, namely the Northeast Monitoring Program (NEMP) , was
established by the National Marine Fisheries Service (NMFS) in
1978. This program is a multifaceted approach, using a variety of
scientific disciplines, to assess the extent to which our marine
environment has been or may be affected "by pollution. As part of
this program the Manned Undersea Research and Technology (MURT)
program of the Northeast Fisheries Center (NEFC) began a research
project in 1978 using in situ diving techniques to determine
benchmark population densities of selected species and pollutant
body burdens of dominant macrobenthic species at sites along the
New England coast, on Georges Bank and offshore submarine canyons
(Figure 1) . The MURT sites are complementary to the overall NEMP
coverage and represent areas difficult to sample with conventional
surface techniques. Nearshore areas are hard bottom substrates
with attached flora and fauna that can be most effectively studied
and collected by divers. The offshore study sites are
biologically rich canyons with ocean floor fauna and substrates
most accurately censused by manned submersibles. This paper will
present the levels of heavy metals (barium, cadmium, copper,
chromium, lead, mercury, zinc) , petrogenic hydrocarbons, and
polychlorinated biphenyls found in our array of samples.

The three general areas selected for study were: 1)
Jeffreys Ledge, Gulf of Maine, 2) Block Island, Rhode Island
Sound, and 3) Georges Bank and adjacent Lydonia and Oceanographer
submarine canyons. Each represents a different and distinct
marine environment. The locations and depth of each station is
presented in Table 1. Samples for analysis were collected from
Jeffreys Ledge and Block Island in 1980 and from the remaining

128

sites in 1980 and 1981.

Pigeon Hill at Jeffreys Ledge in the Gulf of Maine was
selected for its pristine nature, accessibility by scuba, and
background of study. The biology and geology of Jeffreys Ledge
has been a subject of study by us and other scientists since 1971.
Surveys of herring spawning areas there have been discussed by
Cooper at al. (1975), the biology and geology by McCarthy et al.
(1979), Sears and Cooper (1978), Witman et al. (1980), Pecci and
Hulbert (1981a, 1981b)

Hulbert
This hard bottom
complex community
communities north

Cooper (1983) .

meters has a

boreal benthic

isolation the benthic community

pollution sources. Three dominant

trophic levels were selected from
algae (Ptilota serrata) , ascidians
stars (Henricia sanquinolenta) .

et al. (1982), and Witman and

undersea knoll at a depth of 3 3

of flora and fauna typical of

of Cape Cod, and because of its

is relatively unimpacted by

species representing different

this site
(Ascidia

for analysis: red
callosa) , and sea

/-200M

45°

J^^LYDONIA CANYON
^s-.-'VCEANOGRAPHER CANYON

40"

Figure 1. Location of collection sites of samples for pollutant
analysis.

129

Table 1.
analysis

Location and depth of sampling sites for contaminant

Station

Depth

Number

Location

( fathoms)

Jeffreys Ledge

42°

46.5'N

70°

14.5'W

Block Island

41°

07.7'N

71°

34.2'W

Mud Patch

40°

29.7'N

70°

12.2 'W

Georges

Bank

40°
67°

42.5'N
27.5'W

Georges

Bank

40°
67°

37.2'N
44.7'W

Lydonia

Canyon

40°
67°

32.2 'N
42.5'W

Lydonia

Canyon

40°
67°

27.6'N
41.5'W

Oceanographer

Canyon

40°
68°

29.6'N
09.2'W

100

Oceanographer

Canyon

40°
68°

25.5'N
09.2 'W

130

The second inshore area we sampled was off Block Island,
Rhode Island Sound. This collection site is a boulder mount
rising from a sand ocean floor at 20 meters to within 8 meters of
the surface. This topographically irregular rocky area supports a
biological assemblage dominated by red algae (Phycodrys rubens) ,
anemones (Metridium dianthus) , and sea stars (Asterias vulgaris)
(Pecci and Hulbert, 1982) . These three species were collected for
pollutant analysis. The Block Island site is impacted
by nearby population and industrial centers, thus the potential
for increased effects from human and industrial wastes.

Our third general area of study is the outer continental
shelf, including oil lease tracts, nearby submarine canyons, and
the "mud patch", an area of reduced current and sedimentation.
Sampling was conducted at seven sites, two each at Oceanographer
and Lydonia submarine canyons, one in the mud patch, and two on
Georges Bank. These stations are located in areas which support
a prolific commercial fishery. Amidst this fishing area, tracts
of ocean bottom have been leased for exploration of oil and gas,
posing some potential for environmental impact from the drilling
activity itself or from the loss of organic compounds. A
background of submersible research on the geology and biology has
been done by Valentine et al. (1980), Cooper and Uzmann (1982)
and Cooper et al. (1983). At each sampling site we selected
endemic species for benchmark evaluations of pollutant body
burdens. The selected samples vary by station but encompass the
American lobster (Homarus americanus) , Jonah crab (Cancer
borealis) , tilefish (Lopholatilus chamaeleonticeps) , sea scallop
(Placopecten maqellanicus) , and surficial sediment.

130

These offshore sites vary topographically as well as
biologically. Station 3, known as the mud patch, is in an area of
reduced current movement resulting in a settling area for
particulate matter from the Georges Bank gyre. Stations 4 and 5
are on tracts leased for petroleum exploration. Stations 6, 7, and
8 are located downstream from lease tracts and are within the
heads of major submarine canyons. The canyon areas have a
background of research effort, are important commercial fishing
areas, and the canyons themselves act as conduits of waterborne
material moving seaward from adjacent shelf areas (Valentine et
al. , 1980) .

MATERIALS AND METHODS

Fish, invertebrates, algae, and sediment were collected for
examination during this study. Sample type and collection method
varied by study site and specimen, while sample preservation,
preparation for analysis, and analytical technique were consistent
by sample and by year.

Collection of specimens from the two inshore sites (Pigeon
Hill and Block Island) were made in situ by scuba divers
concurrent with other studies. Samples were collected from
Jeffreys Ledge (Pigeon Hill) in July, 1980, and from Block Island
in June, 1981, by divers detaching material from bedrock and
placing it in appropriate containers. Upon return to the surface
collected material was frozen until analysis time.

Collections of offshore samples from the Georges Bank,
canyon, and mud patch areas were made during July of 1980 and
1981 concurrent with a manned submersible (JOHNSON-SEA-LINK)
photographic survey. Collection techniques for the offshore
samples were as follows: lobster and crabs were trapped at each
site by use of standard commercial traps. Adult specimens of
both species were used for analysis. Adult tilefish (60-100 cm
total length) were procured by hook and line from the research
vessel R/V JOHNSON and immediately frozen whole. Adult scallop
and sediment samples were collected using the hydraulic arm of the
submersible. They were placed in external containers for return to
the surface where they were transferred to appropriate containers
and frozen until analysis time.

Chemical analysis of our samples was done by Cambridge
Analytical Associates of Watertown, Massachusetts. A minimum of
100 grams of material for analysis (wet weight) was delivered to
them in a frozen condition. Dissections of lobster, crab,
scallop, and tilefish were done to procure the desired flesh for
study. Crab tissue was a composite of seven to ten individuals,
with flesh from walking legs and pincer claws combined for an
edible meat sample and, hepatopancreas combined for an internal
organ sample. Lobster tissue (edible portion of chelipeds and
abdomen combined) was a composite of ten specimens; the lobster
egg sample was the combined eggs from seven berried females.
Flesh from each tilefish was dissected from the right dorsal
musculature just posterior to the head, excluding skin and scales.
The remaining samples (algae, tunicates, sea stars, sediment) were
subsamples from about 100 grams of composited material.

131

Analysis for heavy metals was performed by flame atomic
absorption, furnace absorption, or manual cold vapor. Organic
components of samples were detected by gas chromatograph with
a flame ionization detector. Protocols were taken from the EPA
document, Methods for the Chemical Analysis of Water and Waste
(EPA 600 479-200) . Analysis of samples was generally completed
within six weeks of delivery.

RESULTS AND DISCUSSION

Heavy Metals

The concentration of metals (ppm wet weight) found in our
samples is presented in Tables 2, 3, 4, and 5, with each table
representing a collection location (Jeffreys Ledge, Block Island,
and offshore) and year. Samples from Pigeon Hill were collected
in 1980 and from Block Island in 1981. Those from offshore were
collected from five sites in 1980 and six in 1981.

Inshore

The prominent benthic species collected from Pigeon Hill were
sea stars, tunicates, and algae. The results of their analyses
for heavy metals are presented in Table 2. Of the two animals
analyzed, sea stars were consistently higher in metal content
(with the exception of zinc) than ascidians. This relative
elevation of metal levels may be due to a magnification
associated with a higher trophic level of sea stars.

Table 2. Heavy metal concentrations found in samples from Pigeon
Hill, Jeffreys Ledge, 1980.

Metal Concentration (ppm wet weight)
Species Ba Cd Cu Cr Hg Pb Zn

Sea star 48.1 1.04 1.84 0.9 0.034 0.46 11.1

(Henricia

sanquinolenta)

Algae 46.4 0.04 1.77 2.3 0.027 1.31 16.2

(Ptilota serrata)

Tunicates 29.1 0.06 0.76 0.7 0.009 0.18 34.2

(Ascidia callosa)

The results of the analysis of Block Island samples (sea
stars, algae, and anemones) is presented in Table 3. Again, sea
stars contained higher levels of most metals. An exception was
the elevated concentration of lead found in the red algae

132

Phycodrys, which may have been due to analytical error
or contamination by a lead fishing sinker nearby at sampling time.
The anemone Metridium had lower levels of all metals.

Samples at Block Island were chosen because of their
numerical importance in the benthic community and also for their
similarity to those collected at Pigeon Hill. Algae from both
sites are small, erect, red forms growing on horizontal oriented
hard substrate. Anemones and ascidians attach to hard bottom
substrate and feed on suspended material. Sea stars collected for
analysis are predatory and represent a higher trophic level. The
trophic equivalence of species between the two inshore sites
gives an opportunity for closer comparison between sites.

Barium levels were apparently elevated at both inshore sites.
The apparent reason for this will be discussed later.

Offshore

Samples were collected from offshore in both 1980 and 1981
with five sites sampled in 1980 and six in 1981. Four stations
were common to both years.

In 1980 samples of tilefish (station 7) , Jonah crab
(stations, 3, 4, 5, 6, and 7), American lobster (station 7), sea
scallop (stations 4 and 5), and surficial sediment (stations 4,
5, and 6) were collected for analysis (Table 4). Edible flesh and
viscera of crab, scallop, and lobster were tested; only edible
musculature of tilefish was analyzed. In addition, newly extruded
eggs from lobsters captured at station 7 were tested.

Table 3 . Heavy metal concentrations found in samples from Block
Island, Rhode Island, 1981.

Species

Metal Concentration (ppm wet weight)

Sea stars
(Asterias
vulgaris)

22.7 0.86

4.1 1.0 0.01 9.4 51.1

Algae
(Phycodrys
rubens)

123.9 0.34

1.65 0.6 0.006 78.6 15.2

Anemones
(Metridium
senile)

1.9 0.08

0.61 ND* 0.01 ND* 13.1

* ND = None detectable.

Jonah crabs were common to all sampling stations and their
metal levels in edible flesh were similar between stations. A
composite sample of crab hepatopancreas from station 7 was tested
to determine metal levels in an internal organ. The
hepatopancreas had elevated levels of all metals when compared to
edible flesh, generally an order of magnitude higher, except for

133

zinc which was similar in concentration to that found in
musculature. Zinc levels were higher for crab edible flesh than
in other species. Also at station 7, lobsters were collected and
their metal concentration in musculature was similar to crab with
the exception of lobster having elevated levels of mercury (0.244
vs. 0.006 ppm). Concentrations of metals in lobster
hepatopancreas were generally not elevated above muscle tissue
with the exception of lead and cadmium (0.62 vs. 0.05 and 19.5 vs.
0.18, respectively). The eggs from berried lobsters at station 7
had similar levels of metals as flesh, with the exception of
mercury (lower) and copper (higher) , both by a factor of ten.
Both the edible adductor muscle and viscera from sea scallops were
analyzed from stations 4 and 5. Variability is evident but, note
that scallop viscera had elevated levels of cadmium. Tilefish
musculature had metal levels within the range of that found in
other flesh with the exception being pronounced lower levels of
cadmium, generally by a factor of 100. Our final samples during
1980 were sediment from stations 4, 5, and 6. In general, when
sediment is compared to living tissue, barium and chromium were
higher, copper was lower, and other metals were similar.

In the following year (1981) and the same month (July) a
second round of sampling was completed at six offshore locations.
There were four stations common to both years (4, 5, 6, and 7);
stations 8 and 9 at Oceanographer were new to the study and
station 3 was omitted. Again Jonah crabs were common to all
stations; lobsters were sampled at stations 7, 8, and 9; scallops
at 4 and 5; tilefish at 6; and surficial sediment at 4,
5, 6, 8, and 9 (Table 5).

As in 1980, crabs had similar metal levels between stations
and again zinc levels were elevated when compared to that in other
flesh samples. Lobster samples of edible flesh had metal levels
in agreement with those of crab, including mercury. Crab values
for mercury were low in 1980 compared to lobster, but were similar
in the following year. This may be due to natural variability or
a sampling artifact. Sea scallops again had high levels of
cadmium in comparison to other samples, although viscera had the
most pronounced elevation (29.65 and 21.75 for viscera vs. 7.56
and 1.54 ppm for adductor muscle ). Tilefish flesh had low levels
of cadmium (0.002 ppm), zinc (4.75 ppm), and copper (0.45 ppm)
when compared to the other samples. Sediment samples had higher
barium, higher chromium, higher lead, and lower zinc
concentrations than the living tissue samples.

Hall et.al. (1978) determined trace element levels in tissue
of a wide variety of commercial marine species from the American
coast. Included were rock crab (Cancer irroratus) , American
lobster (Homarus americanus) , tilefish (Lopholatilus
chamaeleonticeps) , and sea scallop (Placopecten maqellanicus) .
The areas of collection and muscle tissue used for analysis are in
agreement with our methods and location. A comparison of metal
levels between reports shows all in relatively close agreement
with the exception of lead. Hall et al . consistently found lead
levels an order of magnitude higher than our data.

134

Table 4. Metal concentrations in offshore samples collected in
1980. Values in ppm wet weight (ND = non detectable).

Station

Metal

PISCES
Tilefish
musculature

MOLLUSCA
Sea Scallops
adductor viscera

4
5
6

Barium

0.21

0.17
0.12

0.59
0.16

4
5
6

Cadmium

0.0002

4.92
0.50

77.0
41.7

4
5
6

Copper

1.79

0.25
1.30

22.2
2.52

4
5
6

Chromium

0.09

0.53
0.39

0.60
0.24

3
4
5
6

Mercury

0.19

0.222
0.014

0.019
0.013

3
4
5
6

Lead

0.90

0.04
1.174

0.38
0.277

Zinc

3.7

11.3
13.7

12.9
24.2

135

Table 4. (cont.) Metal concentration in offshore samples collected
in 1980. Values in ppm wet weight (ND = none detectable).

CRUSTACEA
Jonah crab American lobster

hepato- Sedi-

Station Metal leg pancreas claw tail pancreas eggs ments

3 Barium 0.14

4 0.11 40.3

5 0.13 39.4

6 0.08 58.9

7 0.06 0.50 0.07 0.12 0.04 0.23

3 Cadmium 0 . 14

4 0.49 0.02

5 0.50 0.01

6 0.33 0. 07

7 1.18 17.3 0.18 0.12 19.5 0.13

3 Copper 9 . 8

4 11.8 1.03

5 10.9 0.25

6 7.7 2.15

7 9.7 40.8 7.38 10.6 18.3 62.0

3 Chromium 0.98

4 0.18 3.1

5 0.22 3.8

6 0.47 11.3

7 0.07 0.92 0.05 0.06 0.07 0.24

3 Mercury 0.03 4

4 0.063 ND

5 0.050 ND

6 0.011 ND

7 0.006 0.064 0.218 0.270 0.087 0.035

3 Lead 0.05

4 0.94 0.40

5 0.08 0.38

6 0.06 0.52

7 0.78 0.23 0.05 0.07 0.62 0.07

3 Zinc 95.6

4 102.6 40.5

5 84.8 1.6

6 77.0 13.6

7 87.1 56.5 37.0 25.9 37.3 39.8

136

Table 5. Metal concentration in offshore samples collected in
1981. Values in ppm wet weight. (ND = non detectable, replicate
sediment samples taken at Stations 8 and 9) .

PISCES

MOLLUSCA

Tilefish

Sea Seal

lops

Station

Metal

musculature

adductor

viscera

Barium

0.39

0.10

0.21

0.16

0.18

Cadmium

7.56

29.65

1.54

21.75

0.002

Copper

10.10

12.06

8.93

17.48

0.45

Chromium

0.20

1.15

0.02

0.66

Mercury

0.40

0.10

0.27

0.22

0.29

Lead

0.06

0.42

0.09

0.06

Zinc

9.14

11.97

23.62

13.11

4.75

137

Table 5 (cont.) Metal concentrations in offshore samples
collected in 1981. Values in ppm wet weight. (ND = none
detectable, replicate sediment samples taken at Stations 8 and 9)

CRUSTACEA

Metal

Jonah crab
lea muscle

American lobster

Station

claw

tail muscle

Sediment

Barium

0.12

8.08

0.25

3.15

0.04

8.27

0.09

0.18

0.17

0.06

7.32,

23.60

0.13

0.14

9.34,

6.81

Cadmium

0.26

0. 19

0.03

0.12

0.07

0.24

0.05

0.01

0.12

0.03

0.15,

0.32

0.13

0.11

0.15,

0.32

Copper

14.70

1.08

16.25

0.62

15.18

1.57

15.95

22.82

14.42

5.02

0.75,

0.71

12.24

28.22

2.16

0.85

Chromium

0.04

4.23

0.04

5.06

0.16

7.28

0.02

5.84,

3.16

0.08

0.17

11.00,

4.81

Mercury

0.88

0.34

0.95

0.23

0.51

0.40

0.33

0.27

0.89

0.57

0.45,

0.95

0.59

0.87

0.08,

0.59

Lead

0.18

5.77

0.04

2.72

0.14

4.33

0.02

0.15

0.12

0.05

3.39,

3.56

0.06

0.04

5.41,

4.62

Zinc

66.44

9.12

69.17

3.25

73.68

10.94

63.92

19.05

89.29

23.23

5.09,

2.49

62.65

18.70

12.32,

3 .54

138

Hydrocarbons

Many of the samples contained straight chain hydrocarbons,
but the presence of interfacing biogenic hydrocarbons (fatty
acids, etc.) made it impossible to identify petroleum
contamination at such low levels. The flame ionization detector
detects not only hydrocarbons but also the fatty acid makeup of
the sample.

Straight chain hydrocarbons typically showed a series of
dominant peaks at retention times between 25 and 38 minutes. This
series of peaks accounted for 40-80 percent of the total peak
areas in the samples, whereas, in the Crude Oil Standard it
accounted for only 9 percent of the total peak area. There were
no straight chain hydrocarbons detected in any of the sediment
samples, nor was the 25-38 minute series of peaks detected. This
suggests that these compounds are of biogenic origin and not from
a petroleum source.

Aromatic hydrocarbons did not show a crude oil pattern. The
lobster egg samples did not appear to contain aromatic
hydrocarbons, but biogenic olefins which also appear, make the
determination of trace amounts of aromatics very difficult.
Aromatics were dominated by a group of three peaks at retention
times between 20 and 24 minutes. These peaks accounted for 3-90
percent of the total peak area for different samples. There was
also a predominant peak at a retention time of 29-30 minutes with
an area percent between 3 and 82. These peaks were not present in
aromatic fractions of the Crude Oil Standard, therefore they are
not from a petroleum input.

Polychlorinated Biphenyls

All samples submitted in 1980 were tested for PCB content by
gas chromatography. No polychlorinated biphenyls were detected in
the sediment samples. However, in crab muscle, lobster tail, and
tilefish, trace levels (20 ppb) were found which may be due to the
presence of interfering compounds of biological origin. Because
of the questionable presence of PCB's we assume they were not
present or were present at very low levels.

Boehm (1978) found PCB's in scallop (1), rock crab (1), and
American lobster (2) from samples collected during a survey for
organic pollutants from Cape Hatteras to the Gulf of Maine. The
crab was collected near the Delaware coast, the scallop and one
lobster near the continental shelf off New Jersey and the other
lobster south of Block Island, Rhode Island. The PCB levels he
found (converted to a wet weight ratio by assuming an 85% weight
loss during dessication) , in the scallop, crab, and two lobsters
were 0.0001, 0.0065, 0.225, and 0.0143 ppm, respectively.

CONCLUSION

The samples collected were for determination of metal and
organic compound concentrations in localized species. The ambient
levels found of metals were within the range anticipated. An
exception was the high barium values found in Pigeon Hill, Block
Island, and offshore sediment samples, which were
disproportionally high. The apparent reason for this was a

139

complicating effect of calcium present in these samples. Small
calcarious worm tubes were attached externally on both algae and
tunicates and calcium compounds are present in sea stars resulting
in an overestimation of barium. Consequently, these abnormally
high values should be viewed with some skepticism. Petrogenic
hydrocarbons and PCB's were at low or nonexistent levels.

The flesh or organs of some species seem to accumulate
specific metals at a high level (Table 6) . The association of
these metals with specific tissues may offer a "watchdog"
relationship for checking a selected tissue to follow a particular
ambient metal level.

Table 6. Potential sentinal body portions for metal contamination
monitoring at Georges Bank and offshore canyon areas.

Sample

Metals with elevated levels

Crab muscle

Crab hepatopancreas

Lobster hepatopancreas

Lobster eggs

Scallop adductor muscle

Scallop viscera

Zn
Ba, Cd, Cu

Cd
Ba, Cd, Cr

Compounds of petrogenic origin were not present in any
appreciable level in our samples. Although interfering biogenic
organic compounds complicated sample analysis, there was no
apparent petrogenic contamination at sampling times. Also, PCB's
were extremely low or nonexistent in our samples.
Anthropomorphic contamination of our samples was minimal.

LITERATURE CITED

Boehm, P.D. 1978. New England OCS Environmental Benchmark Draft
Final Report - Chap. 4. Energy Res. Co., Inc., 185 Alwife
Brook Parkway, Cambridge, Ma. 628 pp.

Cooper, R.A. , J.R. Uzmann, R.A. Clifford, and K.J.Pecci. 1975.
Direct observations of herring (Clupea harengus harengus L.)
egg beds on Jeffreys Ledge, Gulf of Maine, in 1974. ICNAF
Res. Doc. 75/93.

Cooper, R.A. and J.R. Uzmann. 1982. Manned Undersea Research and
Technology Program Fiscal 1981 NEMP Report. Northeast
Monitoring Program. Annual Report, NOAA-NMFS, Sandy Hook,
N.J. 44 pp .

Cooper, R.A., P. Valentine, J. Uzmann, R. Clifford, A. Shepard,
and A. Hulbert. 1983. Manned Undersea Research and
Technology Program, Fiscal 1982 NEMP Report. Northeast
Monitoring Program Annual Report, NOAA-NMFS, Sandy Hook, N.J.
51 pp.

140

Hall, R.A. , E.G. Zook, and G.M. Meaburn. 1978. National Marine
Fisheries Service Survey of Trace Elements in the Fishery
Resource. NOAA Technical Report NMFS SSRF-721. 313 pp.

McCarthy, L. , C. Gross, R. Cooper, R. Langton, K. Pecci, and J.
Uzmann. 1979. Biology and Geology of Jeffreys Ledge and
Adjacent Basins: an Unpolluted Inshore Fishing Area, Gulf of
Maine, NW Atlantic. ICES, CM. 1979/E:44. 12 pp.

Pecci, K.J. and A. W. Hulbert. 1981a. An interim report on the
Pigeon Hill dive site. Coastal Ocean Pollution Assessment
News, Vol. 1(3) .

Pecci, K.J. and A.W. Hulbert. 1981b. Manned Undersea Research and
Technology diving activity results at Pigeon Hill 1980.
Northeast Monitoring Program Annual Report, NOAA-NMFS, Sandy
Hook, N.J. 21 pp.

Pecci, K.J. and A.W. Hulbert. 1982. Manned Undersea Research and
Technology diving activity results at Pigeon Hill and Block
Island, 1981. Northeast Monitoring Program Annual Report,
NOAA-NMFS, Sandy Hook, N.J. 15 pp.

Sears, J.R. , and R.A. Cooper. 1978. Descriptive ecology of
offshore, deepwater, benthic algae in the temperate western
North Atlantic Ocean. Mar. Biol. 44: 309-314.

Valentine, P.C., J.R. Uzmann, and R.A. Cooper. 1980. Geology
and biology of Oceanographer submarine canyon. Mar. Geol. 38:
283-312.

Witman, J.D., and R.A. Cooper. 1983. Disturbance and contrasting
patterns of population structure in the brachiopod
Terebratulina septemtrionalis (Couthouy) from two subtidal
habitats. J. Exp. Mar. Biol. Ecol. 73: 57-79.

NOAA Symp. Ser. for Undersea Res. 2(2), 1987 141

STUDIES OF THE WATER COLUMN, SEDIMENTS, AND BIOTA AT THE
NEW YORK BIGHT ACID WASTE DUMPS ITE AND A CONTROL AREA

William C. Phoel

Robert N. Reid
David J. Radosh

Peter R. Kube
Steven A. Fromm

U.S. Department of Commerce

National Oceanic and Atmospheric Administration

National Marine Fisheries Service

Northeast Fisheries Center

Sandy Hook Laboratory

Highlands, New Jersey 07732

ABSTRACT

In situ studies of the New York Bight acid waste disposal
site and a control site on the Cholera Bank 10 km to the north-
northeast were carried out in August, 1982. Visual observations,
sediment samples for infaunal analyses, and color videotape were
taken to determine if there were differences between the two
sites. Visual observations revealed no obvious differences in the
condition of the animals at each site, and only minor differences
in abundance. Core samples from the disposal site had slightly
lower species diversity and numbers of polychaetes and crustaceans
than did control samples. The water column and sediments at the
disposal site were quite different from those at the control area
in that the dumpsite had high concentrations of floe and
aggregates of this floe. No material of this kind was observed at
the control site.

INTRODUCTION

The New York Bight acid waste disposal site, located
approximately 2 8 km due east of Long Branch, NJ (Figure 1) ,
received for 33 years (1950-1982) the by-product from the
manufacture of titanium dioxide at a rate of up to 2 million wet
tons per year. The principal component of this waste is sulfuric
acid, containing ferrous sulfate, residual ilmenite ore and some
titanium dioxide, which when dumped, created a ferrous hydroxide
flocculate which colors the water yellowish-green (Bermingham,
1982).

The dumpsite, known locally as the acid stain, has been in
the past an area frequented by sport fishermen. Environmental
groups have campaigned to have the dumping ended, claiming
environmental degradation due to the dumped acid waste material.
The U.S. Environmental Protection Agency (EPA) at the same time
made a decision to permit the continuation of this dumping, based
in part on NOAA data. Most acid waste disposal ended in 1982 when
National Lead Industries, the major dumper, closed its Sayreville,
NJ plant.

142

LOWER
BAY

SANDY
HOOK

AMBROSE*

40°40-

JONES
BEACH

40°30-

•SEWAGE
SLUDGE

DREDGE*
SPOIL

CHOLERA
BANK

7400

• CELLAR
DIRT

•

a r\°r\r\-

•

ACID
WASTE

-•-..> ,■••-

V& <5,

: "* - '•

c'....

-......_

*" -•..'." ^ "

) :m WRECKS

73°50

73°40

Figure 1. Sampling sites in the acid waste disposal area and
Cholera Bank are designated by dots in the respective areas.

In spite of the arguments, pro and con, over the effect of
the acid waste on the biota in the water column and sediments
there has been little direct observation or photodocumentation to
substantiate either position. We therefore decided to visually
inspect the dumpsite, record these observations on video tape and
collect sediment samples for analyses.

MATERIALS AND METHODS

On 3 August 1982, the R/V KYMA was moored fore and aft in the
greenish-yellow stain from a dump we observed approximately one

143

hour before. The site was at 40°18.55'N, 073°38.80'W, based on
Loran C readings, in 26 m of water. Diving operations began
approximately two hours after the dump was completed using
techniques and equipment designed for environments contaminated by
hazardous materials (Phoel, 1978) . Besides the direct visual
observations of the six divers taking part in the investigation,
about one hour of color video tape and five random sediment cores
(78.5 cm2 by 7 . 5 cm) were taken for infaunal analysis.

The next day the ship was moored at a site 10 km bearing
035°T from the dumpsite in 25 m of water (40°23.18'N, 073°34.70'W)
in an area known as Cholera Bank. After videotaping and sediment
sampling as previously described, the ship was remoored at the
dumpsite where another dive was made for observations and
videotaping.

One dive was made at each site to obtain the sediment
samples, and five dives, covering about 3 60 m2 of bottom each,
were made for videotaping: three at the dumpsite and two at the
Cholera Bank control site. Two additional dives were made at the
dumpsite for visual observations only. The total dumpsite and
control site dive times were 3.0 and 1.5 man hours, respectively.
Video tapes were used to confirm observations, which were reported
back to the ship by underwater communication rather than being
obtained at post-dive debrief ings.

The sediment samples for infaunal analysis were sieved to 0.5
mm, fixed in formalin and preserved in alcohol. Organisms from
the cores were later sorted and identified using dissecting
microscopes.

RESULTS

As the research ship approached the dumpsite, which was
marked by light green waters, its propeller churned up water which
was a bright yellow-green in color. Divers observed fairly clear
water just under the surface with visibility about 2 m. A
whitish, stringy gelatinous material, commonly observed
throughout the New York Bight, was seen above the thermocline.
Visibility diminished gradually to the thermocline where it was
less than 2 0 cm due to a very fine, bright yellow floe. At 8 m
the thermocline was strong and about 2 m thick. Under the
thermocline the water was dark but very clear (visibility ~4 m)
with pea-sized yellow-orange aggregates uniformly distributed at
10-20 m"3 throughout (Figure 2) . Figure 2 illustrates the patch
covering of the bottom by these aggregates which the current
gently shifted and which tended to concentrate in troughs of sand
ripples. Sediments were of a yellow-brown, medium/fine sand with
large numbers of burrowing sea anemone, Ceriantheopsis americanus
(see Table 1) .

Observations in the acid dumpsite the following day, when no
new dumps were observed, showed the water just under the surface
to be clearer and the floe at the thermocline made up of larger
particles. Under the thermocline the water was again dark and
clear but the yellow-orange aggregates, while uniformly
distributed, were less numerous in the water. The number of

144

aggregates on the bottom, however, had substantially increased to
almost cover the bottom.

The control site, out of the direct influence of dumping
activity, also had a similar strong thermocline at 8 m with
surface and bottom temperatures of 2 4.6°C and 10.3°C respectively.
The visibility just under the surface was about 3 m and remained
the same down to the bottom where it was just slightly darker.
Visually, the only indication of the thermocline was a light

Thermocline

DC
LU

LLI

Q_
LU
Q

10-

? 15

m^.

teSS

Figure 2 . Conceptual drawing of the water column and seabed in the
acid waste disposal site approximately two hours after a dump. The
shading depicts an increased concentration of fine flocculant
material on the thermocline. Below the thermocline the water is
clear but dark with a uniform distribution of floe aggregates to
the bottom. Numerous aggregates are depicted rolling on the seabed
with high concentrations in the troughs of sand ripples. Rock
crabs and the numerous anemone-like Ceriantheopsis are shown.

145

accumulation of the common stringy gelatinous material above it.
The sediments were of brown fine sand with some dark brown organic
material on the surface.

Table 1. Relative abundance of pelagic and epibenthic animals at
the control and acid waste disposal sites.

Species

Acid Site

Control Site

Ceriantheopsis americanus

Cancer irroratus (adults)

Asterias forbesi

Cliona celata

Paqurus sp.

Flounder (unidentified)

Ctenophores (unidentified)

Juvenile fish (unidentified)

Shark (unidentified)

Skate (unidentified)

High High

Moderate Moderate

Rare and small Occasional; larger

Occasional Occasional

None

One

Occasional

One

High

Low

One

None

Table 1 compares the relative abundance of biota observed at
each site. With the exception of the stringy gelatinous material
present above the thermocline at both sites, no material, living
or otherwise, was observed in the water column at the control
site. At the dumpsite a 1.5 m unidentified shark was noted
swimming slowly at the surface, ctenophores were common above the
thermocline where visibility permitted observation. Juvenile
fishes, 3-4 cm in length, were seen near the surface and small
juveniles (1-2 cm in length) were observed among the floe
particles at the thermocline. One flounder and one skate, both
unidentified, were observed at the sea floor of the dump and
control sites respectively. At both sites Ceriantheopsis
americanus was the most abundant (ca. 20/m2) benthic species
observed. Most of the C. americanus at the dumpsite had an area
of 10-15 cm in diameter which was clear of aggregates around the
stalk. The stalks also appeared to be higher than those at the
control site. Rock crabs, identified as Cancer irroratus, and an
occasional sulfur sponge, Cliona celata, were observed to be of
the same size and abundance at both sites; however, only at the
control site were numerous small (about 0.5 cm in length) crabs,

146

possibly C. irroratus, observed. Starfish, Asterias forbesi. were
observed at both sites but those at the dumpsite were smaller and
much less abundant than those at the control. The dumpsite had an
occasional hermit crab (Pagurus sp.) whereas none were seen at the
control.

Results of macrofauna analyses in core samples are summarized
in Table 2. Number of species, number of individuals and species
diversity (Shannon-Weaver) were all higher at the control site
than at the acid dumpsite. Two-thirds of the difference between
sites in number of individuals was due to polychaetes. Relative
differences in numbers of individuals and species between sites
were greatest for crustaceans.

Table 2 . Summary statistics for macrofauna of acid and control
sites, with numbers of individuals and species of most abundant
major taxa. Data are means (+ standard error) of five 78.5 cm2
core samples.

Acid Site Control Site

Number of species (S) 7.6+0.6 11.4+0.9

Number of individuals (N) 11.2+1.4 26.0+3.3

Species diversity (H1) 1.90+0.09 2.15+0.12

Equitability (J1) 0.94+0.02 0.89+0.03

Polychaetes S 4.4+0.7 6.8+0.6

N 5.8 + 1.2 16.4 + 2.5

Crustaceans S 0.2+0.2 2.4+0.8

N 0.2 ± 0.2 6.2 + 2.5

Molluscs S 2.0+0.3 1.6+0.5

N 4.2 + 1.0 2.6 + 1.0

DISCUSSION

During the summer, when a strong thermocline exists, the
precipitated floe of ferrous and ferric hydroxides is
concentrated at the thermocline. Aggregates of the floe, and
probably other material, are formed and become dense enough to
pass through the thermocline into the bottom waters, eventually
accumulating on the sediments. The substantially higher
concentrations of aggregates on the sediments compared to
concentrations in the sub-thermocline waters indicate that the
aggregates settle slowly onto the sediments. Without renewed
input, the water column should be cleared of aggregates within a

147

few days; however, the persistence of the aggregates on the bottom
would be determined by the direction and speed of bottom currents
as well as dissolution of the aggregates. It is speculated that
in the absence of a thermocline, if the density of a floe is
greater than the density of water, there would be a gradual
increase in floe concentration with depth and aggregate formation
would take place on the bottom. If the density of the floe is not
greater than that of the water the floe would remain at the
surface and be rapidly dispersed by tidal currents and the rougher
winter seas.

A strong north-northwesterly surface tidal current had
negligible effects on the floe at the thermocline and aggregates
on the bottom except for slight oscillations. As no net transport
of the aggregates was observed during this period of near maximum
tidal current velocity and no floe or aggregates were observed at
the control site to the north-northeast, it is our tentative
conclusion that storms are required to disperse the aggregates to
any considerable degree, at least when a strong thermocline is
present.

Table 1 indicates only small differences in abundance and
size of the animals observed at each site suggesting that, for
these species at least, there are no major effects of the acid
wastes. A possible explanation for juvenile fish being more
abundant at the dumpsite, if indeed they are, is that their
predators avoid the wastes and/or cannot find prey as effectively
in the floe. The latter effect could also account for the higher
numbers of hermit crabs at the dumpsite; the skate, a principal
predator of these crabs, was seen at the control site but not the
dumpsite. The greater size or extension above the sediment
observed in Ceriantheopsis at the dumpsite could be another effect
of reduced predation. Obviously, more observations would be
required to determine whether abundances at the two sites are
statistically different.

The data in Table 2 may indicate minor effects of acid
dumping on benthic macrofauna, especially crustaceans.
Crustaceans as a rule are thought to be sensitive to contaminants,
and apparently have been excluded from much of nearby
Christiaenson Basin by pollution (Boesch, 1982) . Contaminant
stress could also be limiting populations of these at the acid
dumpsite. Again, the small size and number of samples collected,
and the lack of corresponding information on sediment grain sizes
and other variables influencing benthic distributions, precludes
rigorous analysis and definitive statements on differences between
sites.

CONCLUSION

From our observations there generally were no obvious
differences in the condition of the biota at the acid waste
disposal site and the Cholera Bank control site, which is in
agreement with conclusions reached by Vaccaro et al. (1972) and
Arnold & Royce (1950) . Only minor differences in the abundance of
animals at the two sites were seen and, as the observations were
temporally and spatially limited, these differences cannot be

148

ascribed to dumping of acid wastes. There were, however,
significant differences between the sites with regard to the
presence and absence of materials related to the dumped acid
wastes, i.e. floe and aggregates, and an associated decrease of
sunlight to the bottom of the dumps ite.

ACKNOWLEDGEMENTS

The authors wish to acknowledge the support of the NOAA
Diving Office, Rockville, MD and Paul Pegnato and Steve Urick of
that office for their assistance.

LITERATURE CITED

Arnold, E.L., & W.F. Royce. 1950. Observations of the effect of
acid-iron waste disposal at sea on animal populations.
Special Scientific Report: Fisheries No. 11, Fish and
Wildlife Service, U.S. Dept. of the Interior: 12.

Bermingham, P.E. Regional Hearing Officer, EPA. 1982.
[Memorandum to J.E. Schafer, Regional Administrator, EPA].
May 13.

Boesch, D.F. 1982. Ecosystem conseguences of alterations of
benthic community structure and function in the New York
Bight region. In: G.F. Mayer (ed.), Ecological stress and
the New York Bight: Science and management, p. 54 3-568.
Estuarine Research Federation, Columbia, SC.

Phoel, W.C. 1978. A diving system for polluted waters. In: The
Working Diver 1978 Symposium Proceedings, p. 232-237.
Columbus, OH.

Vaccaro, R.F., G.D. Grice, G.T. Rowe, & P.H. Wiebe. 1972. Acid-
iron waste disposal and the summer distribution of standing
crops in the New York Bight. Water Res. 6: 231-256.

NOAA Symp. Ser. for Undersea Res. 2(2), 1987 149

BIOMONITORING OF DEEP OCEAN OUTFALLS IN HAWAII

Anthony R. Russo
Water Resources Research Center
University of Hawaii, Honolulu

ABSTRACT

In the process of seeking waivers (for secondary to
primary treatment) from EPA, the City and County of Honolulu has
implemented a biomonitoring program on its deep (200') ocean
outfalls using the two man submersible Makalii . The purpose of
the monitoring program is to evaluate the impact of sewage
effluent discharge on the indigenous populations of marine biota
in the vicinity of the deep ocean outfall diff users. From the
submersible, visual counts of fish were made along a pre-
determined length of pipe, videotapes and 35 mm slides were taken
of any biota living on or near the outfall pipe for further
analysis, and sediment samples were taken for organic content and
microfaunal analysis. Results have shown that vigorous water
motion removes suspended and dissolved matter rapidly and that the
new ocean outfalls have acted as artificial reefs, attracting
large numbers of fish, algae and invertebrates of different
species. There are large aggregations of the snapper Lutjanus
kasmira. This fish is of potential commercial value, and deep
ocean outfalls may be future fishing sites.

INTRODUCTION

As part of a biomonitoring program required of the City and
County of Honolulu by the Environmental Protection Agency deep
ocean outfalls (200 ' ) are surveyed using the two man submersible
Makalii, originally built as the Star II by General Dynamics. The
submersible operation is funded by the National Oceanic and
Atmospheric Administration (NOAA). In 1981, 1982, and 1984, field
work was done to examine the effects of effluent discharge from
the Sand Island outfall located off Honolulu, and the Barber's
Point outfall located about 18 miles west of Pearl Harbor. The
Mokapu outfall was surveyed in 1978 and 1979 (Figure 1) . Specific
goals were to: 1) conduct preliminary assessments of the
hydraulic performance of the outfall and 2) conduct periodic
assessments of the environmental impact of the discharge. In
order to qualify for a waiver from secondary to primary treatment,
the City and County of Honolulu maintains an intensive
biomonitoring program which, consistent with goal 2, includes
monitoring of benthic communities and fish populations and the
analysis of infauna of the surrounding sediments.

METHODS

The submersible Makalii was used to descend to the diffuser
depth. Two visual and photographic transects (both video and 3 5
mm) were made, one on each side of the outfall pipe down a fixed
length of pipe. A species list was made of all macroinvertebrates,

150

Waianae

Mokapu

Barbers Pt

Figure 1. Sewer outfall locations, Oahu, Hawaii.

fish were counted and identified, and samples of flora and fauna
were collected using the remote controlled sampling arm (arm
performance was recorded on videotape and 3 5 mm photographs) .
Three replicate samples were taken of sediment for micromollusk
analysis.

RESULTS AND DISCUSSION

At the Sand Island diffuser, during the 1982 dive, up to one-
fourth of the visible diffuser ports appeared to be blocked or
clogged with debris. Operational diffuser ports at the proximal
(east) end of the pipe appeared to be discharging significantly
greater quantities of effluent than ports toward the terminal end
of the pipe. These qualitative differences were noted from the
size and shape of effluent streams that were visible in the water
column. Some ports still remained clogged during the 1984 dive.
Visible effluent streams extended approximately 1 to 3 m from the
diffuser port. All effluent particles and discolored water masses
emanating from the diffuser ports were observed to disperse
horizontally, with the prevailing current, or in an upward
vertical direction. In 1981, 1982 and 1984, no effluent
particles were ever observed settling on the ocean floor.

During all dives the effects on benthic sand dynamics due to
the outfall structure were observed. A net seaward flow of sand
appeared to be down slope in the area of the outfall pipe.
Approximately half of the outfall structure (distal end) is acting
as a dam to this flow of sand, with a resulting accumulation of
sand on the shoreward side of the pipe and loss of sand on the
seaward side. An additional observation was that the outfall pipe
appeared to be rotated toward the south, perhaps from the weight
of the accumulated sand pushing in that direction. The City and
County of Honolulu, in order to alleviate the blockage of the
discharge ports, is considering the installation of telescopic
ports which rise above and discharge 6' above the pipe. Other
remedies are under study.

At the Barbers Point outfall, no adverse hydrodynamic
performance was observed. During dives in 1981, 1982 and 1984 all
ports were discharging vigorously. No sand drift build up was

151

observed.

The environmental effects of the outfalls can be divided into
two broad categories: alteration of the physical habitat; and
alteration of the physico-chemical components of the water column
and benthic surface, which in turn affects the metabolic
functioning of the benthic community. At Barbers Point and Sand
Island, the outfall pipe and base of armor rock provide a complex
of hard substratum that is qualitatively very different from the
flat carbonate sand bottom characteristic of the 200 ■ depth. The
solid surface provides attachment surfaces for sessile benthic
species, while the spaces between armor rocks provides shelter for
small fish and motile invertebrates. At Sand Island and Barbers
Point, juvenile damsel fish (Chromis leucurus) are present in
large numbers. Sea urchins and sea cucumbers abound, especially
adjacent to and on top of the pipes. The continuous flow of
effluent material provides a supply of organic particulates to
organisms residing in the pipe-rock community. Thus, sessile
filter feeders that have attached to the hard surfaces and
particulate feeding fish have a continuous and easily accessible
food supply.

At the Mokapu outfall on the North Shore of Oahu, bryozoans
have been seen (Russo et al. 1981) which indicates a moderate
flux of organic material settling to the bottom. These organisms
cannot exist in heavy particulate fluxes since they die by
smothering. The presence of these filter feeders may be good
indicators of an outfall environment with light particulate
buildup (Russo et al. 1982). Bryozoans were not seen at Sand
Island. During the May 1984 dive on Sand Island, large
aggregations of white sponge were observed for the first time.
Being filter feeders, they seem to thrive in high particulate
loads.

There appeared to be no significant deleterious effects on
the benthic surface from the sewage discharge at the Barbers Point
and Sand Island outfalls. There is some discoloration of the
sediments near the diffuser ports at Sand Island, but, sediment
micromollusk analysis showed no anomalous or deleterious effects
of the effluent. The sediments near the Barbers Point outfall
diffuser were white, but, aggregations of sludge particles are
accumulating and should persist until primary treatment begins in
December 1984.

The combination of increased habitat complexity and shelter
and a continual source of food may initially provide an ideal
environment for populations of fish. Figure 2 shows that there
was an increase in the total fishes at the Mokapu diffuser in
1979, mainly due to the appearance of the snapper taape, Lutianus
kasmira. The number of herbivorous fishes decreased in deference
to the taape at both outfalls. Results of dives on the Mokapu
outfall also showed a slight increase in species richness from
1978 to 1979, as the diffuser was approached. Eighty percent of
the fish counted were the carnivore Lutianus kasmira. Large
numbers of surgeonf ish (Acanthuridae) , goatf ish (Mullidae) and
wrasses (Labridae) were also seen.

In 1984, conditions at Barbers Point changed dramatically:
The outfall which was previously discharging at 13% of its rated
plant capacity (25 mgd) , began discharging raw sewage at 60%

152

600

f 1 1978

C\J

%?A 1979

( ) Number of species

o
z

X
CO

400

—

U-
O

o
o

200

2
<

(16)

(ID

(7)

(18
(13)17

(12)

(7)

(14)

(DIFFUSER)

DEPTH (m)

Figure 2 . Relative abundance of fish at Station B on the Mokapu
outfall. Ninety per cent of the fish counted at 3 0 m in 1979 were
of one species, Lutianus kasmira.

of its capacity. There was a noticeable decrease in fish
populations, especially in the large aggregations of the yellow
snapper Luti anus kasmira. During the 1984 dive, none were seen,
whereas in 1981 and 1982, they dominated the outfall fish
populations (Table 1). In December 1984, primary treatment will
commence and an increase in fish populations are expected in 1985.
The yellow snapper (taape) may or may not recolonize the outfall
environment.

The snapper taape (Lutianus kasmira) was introduced to Hawaii
in the mid '50s essentially as a potential food fish. This fish
seems to disperse rapidly and to quickly exploit new habitat
space. There have been dramatic increases in sightings by divers,
and fishermen report significantly higher catches in recent years
than normal. The total landings of taape from all the islands
have increased from 1000 pounds in 1967 to 100,000 pounds in 1981,
netting about $70,000 (Tabata 1981).

Being a predator of small free swimming prey (Hobson 1974) ,
taape may put great pressure on the juvenile fish stocks of other
species seen at the diffuser, and could cause a sharp decline in
diversity and abundance of fish there. Increases in taape have
been reported by local fishermen, in areas where they also
complain of declines in preferred species such as goatfish
(Mulloidichthys and Parupeneus) , big eye (Priacanthus) , and
squirrelf ish (Myripristus) . There is no scientific evidence to
indicate that taape is outcompeting or overlapping in niche with
these other species, however, stomach contents do indicate that
the taape may be a general carnivore taking, along with

153

Table 1. Fish species abundance from Barbers Pt. deep dives
(visual counts from the submersible Makalii)

Family: Acanthuridae (Surgeon fish)
Naso literatus
Naso hexacanthus
Acanthurus niqoris
A. niqrofuscus
Zanclus cornutus
Total

Dec. 1981

March 1982

Mav 1984

i fish)

Family: Pomacentridae (Damsel fish)

Dascvllus albisella

> 50

Chromis leucurus

>100

>150

>100

C. verator

>200

Total

>350

>370

>112

Family: Chaetodontidae (Butte

rfly fish)

Chaetodon miliaris

>100

C. multicinitus

C. auricfa

C. fremblii

Forcipiaer flavissimus

Holacanthus arcuatus

Heniochus acuminatus

Total

>114

Family: Mullidae (Goat fish)

Mulloidichthys f lavolineatus >100

Parupeneus multifasciatus
P. cyclostomus
P. porphyreus
Total

>110

> 50
11

3
9_

> 78

>20
6
0
0

>26

Family: Labridae (Wrasses)

Labroides phthirophacrus

Family: Balistidae (Trigger fish)
Balistes spp.
Melichthys niqer
Total

Family: Scaridae (Parrot fish)
Scarus spp.

Family: Lutjanidae (Snappers)
Lutianus kasmira

>500

Family: Holocentridae (Squirrel fish)
Mvripristis murdjan 8

TOTAL

>1083

>500

>20
>1117

0
>189

154

crustaceans, juveniles of the above mentioned species. There is
no indication that taape is eaten by its cohabitors (Tabata 1981) .
Whether or not there is a reciprocal density dependent
relationship between taape and its cohabitors is not clear, but, a
definite increase in abundance of this fish over the last 20 years
and its rapid dispersal to all islands is well documented.

Even though taape is fished, it is considered of secondary
importance as a commercially valuable fish. It is only taken when
other more commercially valuable fish are absent. The low demand
for taape by consumers and fishermen simply lies in the fact that
it is a colorful yellow fish with pale flesh. Local fish
consumers traditionally prefer "red" fish. Most consumers who try
taape consider it as tasty as the other commercially valuable reef
and shore fish. The University of Hawaii Sea Grant Program has
begun a campaign to "re-educate" fishermen and consumers about
the palatability and market value of taape. Progress is slow;
traditions die hard as most fishermen still consider the taape as
a "junk" fish (Tabata 1981) . If these cultural biases can be
removed and the demand for taape increased, along with its price
per pound, the culling of this species will not only be of
commercial value, but also ecologically efficacious since it will
insure the stability and diversity of the fish community. Since
sewer outfalls attract large aggregations of taape and its
cohabitors, these areas could be used as fishing grounds (Russo et
al. 1979). Taape are readily caught with gill nets and purse
seines and, since Hawaiian sewer outfalls are presently at
depths between 30 and 60 meters (100-200 ft) , the outfalls are
easily accessible to fishermen.

LITERATURE CITED

Hobson, E.S. 1974. Feeding relationships of Teleostan fishes on

coral reefs in Hawaii, Fish. Bull. 72:95.
Russo, A.R., S. Dollar, and E.A. Kay 1979. Ecological

observations off the Mokapu ocean outfall. WRRC, University

of Hawaii No. 122.
Russo, A.R. , S. Dollar and E.A. Kay. 1981. Benthic ecosystem and

fish populations off the Mokapu Outfall, Water Resources

Research Center, University of Hawaii Tech. Memo 65 (June) .
Russo, A.R. , S. Dollar and E.A. Kay 1982. Ecological

observations on benthic and fish populations at a marine

sewer outfall: a second post installation study. WRRC,

University of Hawaii No. 132.
Tabata, R.S. 1981. Taape: What needs to be done. Paper No. 46,

Sea Grant Program, University of Hawaii.

NOAA Symp. Ser. for Undersea Res. 2(2), 1987 155

WATER QUALITY OF NEWLY DISCOVERED SUBMARINE GROUND WATER
DISCHARGE INTO A DEEP CORAL REEF HABITAT

George M. Simmons, Jr.

Department of Biology

Virginia Polytechnic Institute and State University

Blacksburg, Virginia 24061

F. Gordon Love
Department of Geology
Virginia Polytechnic Institute and State University
Blacksburg, Virginia 24061

ABSTRACT

The detection and measurement of water quality from submarine
ground water discharge (SGWD) into a deep coral reef habitat was
made in the Key Largo National Marine Sanctuary. The significance
of this discovery is the importance of the water quality to
perturbation and productivity of deep coral reef habitats and the
contributions to sea floor processes at the sediment/water
interface. SGWD was collected at 35 m in two localities in the
sanctuary between November 29 and December 3, 1983 using seepage
meters. Flow rates were- 3 1/hr at the first site and -40 ml/hr
at the second site. Water sampled directly from the meters at
both sites showed oxygen values of 0.30 and 2.32 mg/1,
respectively; and, 10 ppt salinity at the first site. Analyses of
the water from both sites showed numerous pesticide peaks and
heavy metal concentrations 100 -10,000X above mean sea water
values. These results indicate a high potential for perturbation
of benthic organisms that exist at the sediment/water interface
where SGWD may exist.

INTRODUCTION

This is the first report of submarine ground water discharge
into a deep coral reef habitat, and into the Key Largo
National Marine Sanctuary specifically. The significance of this
discovery is important because of the implications to the
productivity and perturbation of coral reef ecosystems. Localized
submarine ground water discharges along the southeastern Atlantic
coast have been known for some time (Manheim, 19 67) . However,
most studies have dealt with localized inputs from seepages or
springs in shallow water, or ground water discharges that have
been detected in deep water (> 2 00 m ) and as far as 12 0 km
offshore. There appears to be no research on inshore discharges
(< 50 m) between these two extremes, particularly in reference to
discharges which may enter the ocean bottom through unconfirmed
aquifers over a large area. The data reported by Manheim (1967)
contained salinity measurements, as evidence of fresh water
presence, but did not contain information regarding pollutants and
nutrients which would be important to benthic ecologists.

Kohout (1966) and Kohout and Kolipinski (1967) appear to be
the first investigators to study the importance of fresh water
seepage to marine ecosystems. Their studies were conducted in

156

south Florida along the shore of Biscayne Bay. After studying the
relationship between biological zonation and ground water
discharge in Biscayne Bay, they concluded "... the distribution of
the organisms correlates so closely with the underlying
hydrological factors that a conclusion appears justified: the
distribution of the organisms is primarily a function of salinity
related to ground water discharge."

Johannes (1980) presented the most definitive work on the
ecological significance of submarine ground water discharge.
While Johannes (1980) acknowledged the fact that ground water
discharge to the sea is widespread, he pointed out that
"...overlooking the fact could lead to serious
misinterpretations of ecological data in studies of coastal
pollution, of benthic zonation and productivity, and of the flux
of dissolved substances between bottom sediments and overlying
water." Johannes studied the shallow water areas off Perth,
Australia and found the submarine ground water discharge delivered
several times as much nitrate to coastal water as did river
discharge. In his concluding statements, Johannes emphasized the
need for additional research examining the influence of ground
water discharge on benthic communities.

Ground water entering a marine habitat can have two different
effects. It could either stimulate the productivity of benthic
communities through nutrient influx, or it could be toxic due to
contaminant influx. The prevailing quality of submarine
ground water could be an important factor in affecting the health
of benthic communities and the prevailing zonation of organisms.

METHODS AND MATERIAL

Ground water discharge was collected at 3 5 m in two
localities in the Key Largo Marine Sanctuary (Fig. 1) between
November 29 and December 3, 1983 using seepage meters as described
by Lee and Cherry (1978) and Lee (1980) . At the first site off
French Reef, two 55 gal metal drum heads, located approximately
10 m apart, were used as seepage meters. The drum heads were 56.5
cm in diameter and had a 15.2 cm wall. They were worked into the
sand/coral bottom until the side opposite the collection port
touched the bottom. The top was tilted slightly so the collection
port side was elevated approximately 2.5 cm. On December 3, we
moved to a site off Carysfort Reef where a plexiglass dome was
used as a seepage meter. The dome was 3 0.5 cm in diameter and was
worked into the sediment approximately 5.0 cm. Water samples
discharging from the seepage meters were collected in 1000 ml
Nalgene bags.

Water samples from the seepage meters were sorted in BOD
bottles that had been rinsed in concentrated HC1, acetone, and
deionized distilled water. Samples were refrigerated, kept on
ice, and returned to Virginia Tech for analyses.

The water samples were filtered to remove the heavy
precipitate of iron oxides. They were then treated with enough
phosphoric acid to lower the pH to 2.0. Pesticides were extracted
with ethyl ether for phenoxy herbicides; 90% hexane and 10%
benzene for general chlorinated hydrocarbons and organic
phosphates; and, chloroform for triazine herbicides. Extracts

157

were analyzed by flame photometric detection (Tracor Model MT
220) , by electron capture using a nickel 63 detector (Tracor Model
MT 220) , and/or by flame ionization using a nitrogen/phosphorus
detector (Hewlett Packard Model 583 08) . Methods of analyses
followed Environmental Protection Agency Manual of Analytical
Methods (1980) with specific modifications by the Virginia Tech
Pesticide Residue Laboratory.

Water samples were analyzed for heavy metals on a Perkin
Elmer (Model 4 60) atomic absorption spectrophotometer. Oxygen was
measured using a microwinkler technique based upon the oxygen
method of Strickland and Parsons (1972) . Salinity was measured
with a calibrated YSI S/C/T meter (Model 33) .

OfWV. V * fwJ§T I , jLThe Elbow
*/-S '^/— French Reef

Key Largo Coral Reef /c^° r— ^ • Research Site

/Marine Soncfuary /o Sy1 £

John Morasses
Pemekamp Reef
° Coral Reef State
*^ Park

Figure 1. Research sites in the Key Largo National Marine
Sanctuary.

RESULTS

By direct observation, we measured 400 ml in eight minutes or
50 ml/min issuing from one of the seepage meters off French Reef
at our first site. This represented 199.2 ml/m2/min or 286.8
L/m2/day. The lowest salinity measured in the latter aliquots
issuing from this meter decreased to 10 ppt and oxygen decreased
to 0.3 mg/1. Ambient salinity of the Gulf Stream was
approximately 3 3 ppt and ambient oxygen at 35 m was ~ 6.0 mg/1.

158

At the Carysfort site, the bottom was a fine-grained depositional
area with no evidence of shells or coral fragments. A thin film
of cyanobacteria covered the bottom and were the only visible sign
of life. No seepage canals were evident in the bottom. Here we
collected 600 ml in 15 hrs after the plexiglass dome was allowed
to flush for 2 hrs. This discharge volume represented 13.2
l/m2/day. Water sampled directly from the dome was found to
contain 2.32 mg/1 of oxygen; whereas, ambient sea water contained
5.8 mg/1 of oxygen.

The nematocide MoCap (O-Ethyl S, S-dipropyl
phosphorodithioate) was the only pesticide clearly identifiable.
The concentration in the submarine ground water was 0.061 ug/1.
There were at least seven other peaks in the hexane/benzene
extraction used for organophosphate and chlorinated hydrocarbons
that cannot be identified at this time. Also several phthalates
were isolated in the hexane/benzene extraction. Five peaks were
isolated in the chloroform extraction (triazines) from the ground
water sample off French Reef and eight peaks from the water sample
off Carysfort. There were also approximately eight peaks in the
ethyl ether extraction from samples at both sites
(phenoxyherbicides) , and one peak suggestive of Tordan (Picloran) .
It is not possible to be more precise about the identification
until more material is collected. Moreover, many of the detected
peaks are probably derivatives of the original compounds which
makes the task of identification even more difficult.

The concentration of heavy metals measured in the submarine
ground water samples is listed in Table 1. The average
concentration of these ions found in sea water is also listed for
comparative purposes. These data show the submarine ground water
discharge had concentrations of heavy metals 100-10, 000X the
average value for sea water. The values presented here are
probably lower than the original levels because the water samples
were filtered prior to analyses. All water samples, when poured
into the B.O.D. bottles contained a red floe which appeared to be
an iron oxide. This was expected from the metal seepage meters,
but it was also characteristic of the water samples from the
plexiglass meter as well. Filtration of the iron oxides certainly
reduced the iron levels and probably some of the other metals as
well .

Table 1. Concentration of Heavy Metals in Ground Water off Key
Largo and an Average Value for Sea Water (Brewer, 1975) .

Copper

Cadmium

Chromium

Iron

Zinc

Lead

Mercury

French Reef
0.199 mg/1
0.171 mg/1
0.04 3 mg/1
3.740 mg/1
0.703 mg/1
0.592 mg/1
0.596 ug/1

Carysfort
0.221 mg/ 1
0.228 mg/ 1
0.067 mg/1
0.840 mg/1
0.57 0 mg/1
0.592 mg/1
0.247 ug/1

Sea Water

.05 ug/1
.10 ug/1
.3 ug/1
2 . 0 ug/ 1
4.9 ug/1
.03 ug/1
.03 ug/1

.00005 mg/1
.00010 mg/1
.0003 mg/1
.002 mg/1
.0049 mg/1
.00003 mg/1

159

The submarine ground water discharges also were analyzed for
dissolved nitrate (Table 2) . The nitrate values show that
submarine ground water discharge can be an important source of
fixed nitrogen compounds in the area. We measured 0.100 mg/1 off
French Reef and 0.103 mg/1 off Carysfort Reef.

Table 2 . Concentration of nitrate in ground water off Key Largo
and a comparison with values form other known submarine
ground water sources .

Nitrate cone.
0.100 mg/1

Source

French Reef

Simmons, 1983 cruise

Carysfort

0.103 mg/1

Simmons, 1983 cruise

Discovery Bay, Jamaica:

Undiluted spring water

1.12 0 mg/1

D'Elia et al. (1981)

Average ground water

8.750 mg/1

D'Elia et al. (1981)

Guam

0.113 mg/1

Marsh (1977)

Caves off St. Croix

0.058 mg/1

Szmant-Froelich (1983)

Coastline, Perth,

1.610-

Australia

5.320 mg/1

Johannes (1980)

Tropical Inorganic

Nitrogen in Tropical

0.014-

Surface Sea Water

0.028 mg/1

Spencer (1975)

DISCUSSION

There are many ways that ground water can become contaminated
(Pye and Patrick, 1983) . Some of these include land disposal of
solid and liquid waste, industrial and domestic wastewater
impoundments, the agricultural use of pesticides, sewage disposal
systems, and deep-well disposal of liquid wastes. The problem is
compounded by the fact that when the constituents of such wastes
interact in the ground water environment, new compounds may be
formed which will vary in their toxicity. Due to the nature of
the slow movement of ground water, the contaminants may remain
localized over long time periods and may not be diluted as rapidly
as they would be in a surface water supply. Many contaminants
have been found in higher concentrations in ground water than in
surface water.

Ground water contamination is an insidious type of water
quality degradation because it occurs underground, unobserved, and
unrecorded. The sources of contamination are not easily
identified, and the contaminants go undetected until the damage is
done. Once detected, the effects are often irreversible and
little can be done to correct the ground water quality problem.

Florida is one of ten states reviewed in detail by Pye and
Patrick (1983). They site 92 known contamination incidents, 58 of
which affected or threatened water supplies. Florida also was one
of three states that reported problems arising from agricultural
practices. Given the charge by Johannes (1980) and the review by
Pye and Patrick (1983), it is interesting that Duursma and Smies
(1982) reviewed the processes related to pollutant transfer
through marine sediments and did not mention submarine ground
water influence, which again probably reflects the lack of

160

research on this topic.

Even though coral reefs are highly productive and generally
resilient ecosystems, they are easily perturbed by natural and
man-made disturbances (Endean, 1976; Pearson, 1981). Endean
(1976) listed the major factors of human activity known to
adversely affect coral reefs and all dealt with surface
activities. Admittedly, many activities such as sewage disposal,
dredging, mining, and land clearing cause adverse effects, but no
mention was made of ground water effects. Pearson (1981) stated
that it may take coral communities several decades to recover from
a natural disturbance (hurricane, cold weather, fresh water
dilution) , and the picture is even less clear in man-made
disturbances where the environment may have undergone permanent
change. Endean (1976) also pointed out how little was known about
the effects of pesticides on coral reef ecosystems.

In the case of coral reef ecosystems, perturbation could be
magnified through the dual effect of pesticides (chlorinated
hydrocarbons and related toxins) and herbicides (photosynthetic
inhibitors) . If the concentration of photosynthetic inhibitors
was high enough in the ground water to kill symbiotic
zooxanthellae, corals could die as guickly as if the pesticide
level was high enough to kill the coelenterate component. The
persistent and continuous demise of Florida's coral reefs could
possibly be explained, in part, by the chronic influx of
pesticide contaminated ground water over past decades.

The lack of information on heavy metal effects is egually
apparent (Endean, 1976) . Perhaps this stems from the fact that
most investigators have ignored the possible significance of
submarine ground water influx.

Coral reef ecosystems stand in stark contrast to all factors
which influence coastal productivity. They generally exist on the
fringes of tropical islands which produce little fresh water run-
off; they are flushed by surface ocean waters usually depleted in
nutrients (Stoddart, 1969) ; and, their associated sediments are
coarse, calcareous, and have little silt or organic matter
(Sepkoski, 1971; Patriquin, 1971). In spite of these factors,
coral reef ecosystems are regarded as one of the more productive
and diverse ecosystems on our planet (Odum, 1971) . Such high
productivity could not exist without mechanisms to conserve,
cycle, and replenish nutrients (Welsh, et. al. , 1979) .

A number of such mechanisms are known. While it is beyond
the scope of this paper to include all mechanisms, some of the
more recent and major processes include such examples as the
association of the coral coelenterate and their symbiotic algae
(Goreau et al . , 1971; Taylor 1973; Muscatine and Porter, 1977);
the role of seagrasses and their decompositional products (Welsh,
et al. , 1979; Zieman et al . , 1979); the role of bacterial
colonization on the mucus nets of coral and the subsequent use of
such mucus strands as food (Sorokin, 1973; Lewis, 1977a, 1977b;
Ducklow and Mitchell, 1979); the role of fish utilization of
seagrass and nutrient transfer through waste products to corals
(Meyer et aJL. , 1983), and the transfer of nutrients from
sediments and feces trapped in reef holes and crevices (Szmant-
Froelich, 1983) . In spite of these conservative cycling

161

processes, the search for nutrient sources and methods of
conservation are still important paradigms in coral reef research
(Szmant-Froelich, 1983) .

Even though fixed nitrogen compounds appear to be the most
frequently limiting nutrient in the marine environment (Muscatine
and D'Elia, 1978), several investigators have reported the
contribution of such compounds by SGWD. Marsh (1977) studied the
nutrient content of ground water input to a shallow reef flat on
Guam and found that ground water seepage had a major influence on
nutrient levels. D'Elia et al. (1981) also studied shallow ground
water inputs (» 2 i) to Discovery Bay, Jamaica and found that such
seepage provided a significant enrichment of nitrogen to the bay.
Johannes (1980) found nitrate levels between 1.610-5.320 mg/1
along a 5 km strip of coastline bordering Perth, Australia. Meyer
et al. (1983) found 0.016 mg/1 and 0.004 mg/1 of NH4+ adjacent to
reefs with and without fish, respectively. Szmant-Froelich
(1983) recently reported high nitrate levels "burping" from coral
caves where she believes nutrients are being regenerated from
decompositional processes. There appears to be little doubt that
submarine ground water discharges will contain fixed nitrogen
compounds that can have a beneficial effect on associated benthic
communities. The prevalence of such contributions by SGWD and the
importance of fixed nitrogen compounds to the nitrogen budget of
coral reef ecosystems deserves additional study.

SUMMARY

Ground water can be a double-edged sword, particularly in
areas like the Florida Keys. In remote coral reef areas,
submarine ground water influx may be the source of nutrients,
particularly phosphate and fixed nitrogen compounds, which would
be beneficial to the coral reef ecosystem. In highly
industrialized and populated areas, submarine ground water
discharge may cause perturbation of coral reefs and contribute to
their eventual demise.

Because the coral reefs of Florida are economically important
to the state and are part of state and national sanctuaries, it is
of the utmost importance to know the quantity and quality of
existing submarine ground water discharges.

ACKNOWLEDGEMENTS

The authors appreciate financial support from Dr. Nancy
Foster, Chief, Sanctuary Program Division, National Marine
Sanctuary Program, NOAA; the NOAA National Undersea Research
Program at the University of North Carolina, Wilmington for
ship time; and Professor R.W. Young and John Burroughs,
Biochemistry and Nutrition Department, Virginia Tech Pesticide
Residue Laboratory, Department of Biology, Virginia Tech for heavy
metal analyses. The authors also acknowledge the help of Dr. Buck
Cox and Mr. Dale Andersen, Environmental Technology, Inc.,
Culpepper, Va. for assistance in collecting and analyzing the
samples. Dr. E.F. Benfield, Biology Department, Virginia Tech
reviewed the manuscript.

162

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415-496. Second Edition. Vol. 2. Academic Press, NY.
D'Elia, C.F., K.L. Webb, and J.W. Porter. 1981. Nitrate-rich

ground water inputs to Discovery Bay, Jamaica: a significant

source of N to local coral reefs? Bull. Mar. Science 31:903-

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Ducklow, H.W. and R. Mitchell. 1979. Bacterial populations and

adaptations in the mucus layers on living corals. Limnol.

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Environmental Protection Agency. 198 0. Manual of analytical

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autotrophs or heterotrophs? Biol. Bull. 141:247-260.
Johannes, R.E. 1980. The ecological significance of the

submarine discharge of ground water. Mar. Ecol. Prog. Ser.

3:365-373.
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Turkey. Feb. 7-12, 1966. pp. 391-413.
Kohout, F.A. and M.C. Kolipinski. 1967. Biological zonation

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Conf. on Estuaries, Jekyll Island, GA.
Lee, D.R. and J. A. Cherry. 1978. A field exercise on ground

water flow using seepage meters and mini-piezometers. Jour.

Geol. Ed. 27:6-10.
Lee, D.R. 1980. Ground water - solute influx. Limnol.

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Lewis, J.B. 1977a. Processes of organic production in coral

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Lewis, J.B. 1977b. Suspension feeding in Atlantic reef corals

and the importance of suspended particulate matter as a food

source. Third International Coral Reef Symposium, Proc. ,

Rosenstiel School of Marine and Atmospheric Science, Univ. of

Miami, Fl. pp. 405-408.
Manheim, F.T. 1967. Evidence for submarine discharge of water on

the Atlantic continental slope of the southern United States,

and suggestions for further search. Trans. N.Y. Acad. Sci.

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163

Marsh, J. A. 1977. Terrestrial inputs of nitrogen and phosphorus

on fringing reefs of Guam. In: D.L. Taylor (ed.), Proc.

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Miami, Miami, FL.
Meyer, J.L., E.T. Shultz, G.S. Helfman. 1983. Fish schools: an

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Muscatine, L. and J.W. Porter. 1977. Reef corals: mutualistic

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27:454-460.
Muscatine, L. and C.F. D'Elia. 1978. The uptake, retention, and

release of ammonium by reef corals. Limnol. Oceanogr.

23:725-734.
Odum, E.P. 1971. Fundamentals of Ecology. Saunders,

Philadelphia, PA.
Patriquin, D.G. 1971. The origin of nitrogen and phosphorus for

growth of the marine angiosperm, Thalassia testudinum, Konig.

Ph.D. Thesis, McGill Univ. 193 pp.
Pearson, R.G. 1981. Recovery and recolonization of coral reefs.

Mar. Ecol. Prog. Ser. 4:105-122.
Pye, V.I. and R. Patrick. 1983. Ground water contamination in

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Sepkoski, J. 1971. Carbonate sands of the Tobacco Bay area.

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(eds.). Seminar on Organism-sediment Interrelationships, pp.

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Sorokin, Y.I. 1973. Microbiological aspects of the productivity

of reef corals. In: O.A. Jones and R. Endean (eds.), Biology

and Geology of Coral Reefs, pp. 17-45. Vol. II, Biol. 1.

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and G. Skirrow (eds.), Chemical Oceanography, Chap. 11, pp.

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Strickland, J.D. and T.R. Parsons. 1972. A practical handbook

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Szmant-Froelich, A.S. 1983. Functional aspects of nutrient

cycling on coral reefs. In: M.L. Reaka (ed.), The Ecology of

Deep and Shallow Coral Reefs, pp. 133-139. Workshop on coral

Reef Ecology, Amer. Soc. Zool., Philadelphia, PA. NOAA Symp.

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Taylor, D.L. 1973. Symbiotic pathways of carbon in coral reef

ecosystems. Helgolander, MS. Meeresunters 24:276-283.
Welsh, B.L., D. Bessette, J. P. Herring, and L.M. Read. 1979.

Mechanisms for detrital cycling in nearshore waters at

Bermuda. Bull. Mar. Sci. 29:125-139.
Zieman, J.C., G.W. Thayer, B. Robblee, and R.T. Zieman. 1979.

Production and export of seagrasses from a tropical bay.

In:R.J. Livingston (ed.), Ecological Processes in Coastal

and Marine Environments, pp. 21-33. Mar. Sci., Vol. 10.

Plenum Press, NY.

CHAPTER IV

SEA FLOOR PROCESSES

NOAA Symp.Ser. for Undersea Res. 2(2), 1987 167

SUBMERGED EVIDENCE OF PLEISTOCENE LOW SEA LEVELS
ON SAN SALVADOR, BAHAMAS

James L. Carew
Department of Geology
The College of Charleston
Charleston, South Carolina 29424

John E. Mylroie
Department of Geology and Geography
Box 2194, Mississippi State University
Mississippi State, MS 39762

ABSTRACT

On a carbonate island such as San Salvador, Bahamas, there
are several prominent geologic features that are indicative of
past sea level positions: reef terraces, wave-cut benches and
notches, and horizontal solution conduit systems. Work on the
subaerial geology of the island has provided evidence for several
episodes of high sea level positions during the past 130,000
years. Use of the Johnson-Sea-Link I research submersible to
investigate portions of the submarine geology of San Salvador has
led to the recognition of several prominent indicators of low
stands of sea level. A preferred horizon for bench or platform
development has been found at -55 m. It can be speculated that
these represent reef-constructive and/or wave-cut features formed
during a sea level stillstand at -55 to -50 m. Additionally,
wave-cut notches and overhangs and horizontal solution conduits
that open onto the island wall occur at a preferred elevation of
-105 m. One large solution conduit was also located at -125 m.
Horizontal solution conduits at preferred horizons in a uniform
lithology argue for a stillstand in sea level at those elevations
for a time period of at least a few thousand, to tens of
thousands of years. These features are documented evidence for
low sea level stillstands at those elevations, but as yet their
chronology has not been established.

INTRODUCTION

Limestone bedrock is vulnerable to solution by acidic
meteoric and ground waters. The presence of carbon dioxide in the
atmosphere and within the soil produces carbonic acid, which
provides the acidity to drive the solution of limestone on a large
scale in natural environments. The landscape produced by
solutional processes is unique and is called a "karst" landscape,
after the type locality in Yugoslavia (Jennings, 1971) .

Karst landscapes are characterized by sinking streams,
springs, closed depressions of a variety of sizes and shapes, and
caves. It is the internal drainage of all or part of the
landscape by solution conduits (or caves) that allow the unusual
surface topography to occur. Contained within the mass of the

168

landscape, caves are protected from the weathering that
obliterates evidence of past conditions on the surface. The
size, shape, flow markings, sediments and mineral deposits of
caves are a direct measure of the conditions on the surface.
Valleys, as they widen and deepen, often remove the features of
earlier times. Caves, however, adjust to new lower levels and
leave behind abandoned upper levels with all their included
information preserved.

When surface waters in karst areas sink, they travel downward
until a barrier to their flow is reached. This barrier is usually
an insoluable lithology or the water table. The position of the
water table, in turn, is controlled by local and regional base
levels. In a situation of abundant and uniform limestone rocks
free of insoluble layers, the elevation of abandoned cave passages
is a measure of past base levels. Conduit size can be measured,
and paleowater velocities can be estimated from flow markings
called ablation scallops on the walls. This yields an estimate of
conduit discharge (cross sectional area x velocity = discharge) .
Sediments in the cave passage provide relative dates, provenance
and fossil material. Calcite deposits such as stalagmites can be
dated by U/Th techniques. From such accumulated data the nature
of change on the surface, and the chronology of the changes can be
established. Throughout the world, detailed studies of caves and
their deposits have provided a wealth of information about the
Pleistocene Epoch.

San Salvador Island, Bahamas (Figure 1) has been examined for
caves to piece together a picture of the Pleistocene climatic
variations and sea level positions. The island offers unique
advantages that allow a maximum data return for effort expended.

MATERIALS AND METHODS

San Salvador Island was selected for this research for many
reasons. First, it has an established field station with access
to the necessary research tools. Second, it is an isolated, small
platform that remains discrete during glacial eustatic sea level
changes. Third, it is a tectonically stable platform subsiding
isostatically at a known rate, so tectonic noise is filtered out
of estimations of sea level change. Fourth, the island is
uniformly limestone to a great depth, so an excellent karst
landscape is developed, and base level is tied to sea level.
Fifth, the surface rocks are all Pleistocene or Holocene in age,
providing boundary conditions for the genesis dates of any feature
found within the rock.

The accessible solution conduits on the island have been
studied in detail, and substantial information on Late Pleistocene
sea level highstands has been gathered. This has been reported in
detail elsewhere (Carew and Mylroie, 1983; Carew et al., 1984),
and will only be summarized here.

As the island is tectonically stable (Mullins and Lynts,
1977) , marine lithologies, such as fossil reefs, exposed
subaerially today must have formed at an earlier, higher sea
level. Solution conduits found above sea level today must have
formed in a fresh water lens positioned by a highstand in sea
level. The island contains numerous outcrops of marine rock, the

169

most notable being the Cockburntown fossil reef on the west side
of the island (Figure 1) . The reef extends for over 700 m as a
ridge rising to 3.5 m above current sea level. Uranium/Thorium
age dating of corals in the reef fix the age of the reef at
approximately 125 ka. Amino acid racemization age dates on shell
material from the reef also fit this time frame, and provide
calibration for amino acid racemization elsewhere on the island.
Sea level 12 5 ka ago is thought to have been at +6 m (Bloom et
al., 1974), and the San Salvador data is in basic agreement.
Numerous solution conduits or caves on the island contain phreatic
(or water table) solution features that have an upper limit of +6
to +7 m. This requires that the water table be in this range at
past times; placed at this elevation by a high sea level. Dating
of the wall rock, an eolian calcarenite, enclosing the conduits at
Lighthouse Cave (Figure 1) by amino acid racemization shows the
rock to have an age of approximately 85 ka. Sea level had to drop
below present levels at 85 ka for the eolian calcarenite (which
extends down to -2 m) to form, then rise to approximately +6 m to
develop the solution conduit, probably during the 80 to 70 ka time
span (Boardman - et al., 1983; Cronin et al., 1981).
Uranium/Thorium dates from stalagmites within the cave show air-
filled conditions at 50 ka. Sea level was below -1 m at 50 ka as

MIAMI

150

miles

( ) NASSAU SS,

u D

VJ o ° SAN SALVADOR ISLAND

BAHAMAS

Figure 1. Location map of the Bahama Islands showing San Salvador
Island and features discussed in the text: A = Lighthouse Cave;
I, II, III, IV = dive sites; xxx = fossil reef.

170

the stalagmite, a subaerial feature, began to form. Stalagmite
growth ceased and a marine layer, indicative of a return to
present sea level, occurred sometime between 47 and 3 5 ka.
Stalagmite growth resumed after 3 5 ka, indicating a sea level
below present until the Holocene. The sea level curve produced
from interpretation of this data is shown in Figure 2 .

-no

+ 5 ■

SEA
LEVEL o-

IN METERS

- - -

t T:_.

^ f t

-5

-10

120

100 80 60 40

TIME

IN THOUSANDS OF YEARS BEFORE PRESENT

Figure 2. Constraints on sea level position over the last 130,000
years. Lines with upward pointing arrows indicate high sea level
at or near the displayed elevation. Lines with downward pointing
arrows indicate sea level somewhere below the displayed
elevation. Data collected by submersible indicates stillstands
at -55, -105, and -125 m, as yet undated.

The data described above has helped refine the Late
Pleistocene sea level curve, but by necessity has been restricted
to identifying and dating high sea level stands. Investigation of
low sea level stands has necessitated examination of tectonically
uplifted areas, such as Barbados and New Guinea (Bloom et al.,
1974) . This requires assumptions about rates of uplift that are
difficult to establish. An alternative is to search for markers
of low sea level beneath the ocean on tectonically stable
platforms, such as San Salvador Island. Solution conduits can be
expected to have formed within the island at a variety of sea
level stillstands during the Pleistocene, as shown diagramatically
in Figure 3. Scuba divers elsewhere in the Bahamas (Williams,
1979; Palmer, 1982, 1984) have entered conduits at depths of up to
-50 m, but deeper penetration is difficult and dangerous. Prior
to 1982 little information was available on solution conduit
development below normal scuba range.

Exploration for solution conduits over the entire Pleistocene

171

eustatic sea level range requires the use of a submersible. This
allows descent to the lowest probable sea levels (-125 to -150 m) ,
and detailed examination upward from that depth. The submersible
used needs to be maneuverable and provide optimum visual
reconnaissance capability. Through the Harbor Branch Oceanographic
Institution and the College Center of the Finger Lakes Bahamian
Field Station, access was gained to the Johnson-Sea-Link I
submersible. A preliminary reconnnaissance was done on the west
wall of San Salvador Island in October 1982, and a broader search
was done at adjacent locations on the island's wall in October
1983.

The search pattern involved dropping directly to -18 0 m then
working upward. If a favorable depth could be determined, a
horizontal search would check for additional conduits. A 35 mm
slide and videotape record was kept of the dives. Videotapes of
dives off San Salvador during other research projects were
examined to see if conduits could be identified.

RESULTS

One dive was made in October of 1982 in order to assess the
feasibility of the program. No solution conduits were found, but
the exceptional capabilities of the Johnson-Sea-Link I for this
type of search were clearly demonstrated. The dive was done on
the west side of San Salvador Island in southern Fernandez Bay
(Dive I, Figure 1), from a depth of -300 m to the surface. The
starting depth was well below the expected depth of any conduits,
but by starting deep, cavities and voids produced by depositional
or non-solution processes could be characterized. This allowed
true solution conduits to be accurately identified on later dives.
The dive also demonstrated that at depths shallower than -60 m to
-75 m, recent coral growth and other biologic activity made
conduits difficult to locate. This depth range is at the lower
limit of scuba capability, and data at these shallower depths can
be obtained from cave diving in Blue Holes. A clearly defined
bench was located at -55 m on this dive.

In October 1983, three dives were conducted (Figure 1) .
Additional data from dating the Cockburntown fossil reef had
indicated that isostatic subsidence was minimal, and conduits
developed by low sea level stands would not be expected below
-150 m. The dives were therefore begun in the -170 to -180 m
depth range and continued upward on the wall with horizontal
traverses at depths that showed promise, because surface work on
subaerially exposed conduits showed that they often clustered
along the base level horizon formed by past high sea level.
Detailed examination of conduits exposed on the sea cliffs
provided an excellent model of what to look for at depth. These
conduits were in the 0.5 m to 1.0 m diameter size range.

Dive II was done in southern Fernandez Bay, south of the
previous year's (Dive I) site. Dive III was done in French Bay,
near Sandy Point, an area of proven conduit development at past
high sea levels (Mylroie, 1983) . Dive IV was done just off Grotto
Beach, another area associated with high sea level conduit
development. The dive site locations are shown in Figure 1.

172

STAGE ONE

STAGE THREE

STAGE TWO

STAGE FOUR

Figure 3. History of Pleistocene cave development in the Bahamas:
A = present sea level; B = solution conduits; C and D = sea level
stillstands during Pleistocene glaciations; E = lowest Pleistocene
sea level; F = interglacial high sea level; G = Blue Hole; dots =
freshwater lens; x = reef.

Stage one: Stable, preglacial conditions (sea level arbitrarily
placed at present levels) . Cave development as solution conduits
is dependent on land being available to support a fresh-water
lens.

Stage two: Falling sea level due to glaciation promotes increased
formation of eolian calcarenite dunes as the entire platform is
subaerially exposed. The freshwater lens drops with each lowering
of sea level producing solution conduits preferentially at
elevations of sea level stillstands.

Stage three: Interglacial high sea level stands produce solution
conduits at elevations above present sea level. Lower conduits
become flooded with marine water, depending on the size and
configuration of the freshwater lens.

173

Figure 3 (cont.) . Stage four; Present conditions. Blue Holes
provide access directly into the island solution conduit system.
Reefs produced during previous sea level highstands are
subaerially exposed. As each glacial cycle is repeated, the
solution conduit system becomes increasingly complex.

Dive IV located two conduits at -125 m. One conduit was less
than 0.5 m in diameter, the other was approximately 1 m in
diameter. Dives II, III and IV all located numerous conduits,
many 1 m or greater in diameter, at a specific depth of -105 m.
This depth was also characterized by notches and overhangs similar
to what is seen on existing wave cut cliffs on the island. During
Dives II and IV, a prominent bench was located in the -50 to -55 m
depth range. The benches were of variable width from 5 to 100+ m,
and often included adjacent pinnacles that ended at the same
depth.

A preliminary examination of eight previous dive videotapes
run during other research projects revealed two additional
solution conduits both at -105 m. One of these dives was
in Fernandez Bay, the other on a seamount north of the island.

DISCUSSION

Data from four dives aboard the Johnson-Sea-Link I on San
Salvador Island, plus review of eight videotapes from other dives,
is a fairly meager data set when compared to the length of the
coast of the entire island. Despite this, definite horizons of
probable past lower sea level stillstands have been identified at
two depths, and a third depth has been implicated (see Figure 2).
Three of the four dives encountered a flat bench at -50 to -55 m.
This can be interpreted either as a wave-cut erosional feature, or
as a reef depositional feature. Either interpretation places wave
activity in the vicinity of -50 m. Biological overgrowth obscures
possible conduits at this shallow depth, and none were observed.
The absence of wave-cut benches at greater depths is
problematical. Evidence of an apparent former subaerial sea cliff
exists at -105 m. We did not look for benches shallower than
-50 m.

Solution conduits were located on three of four dives at
-105 m. Videotapes of two other dives also show conduits at this
depth. This depth coincides with an apparent drowned sea cliff,
and large number of conduits were formed, within a very narrow
vertical range of no more than a few meters. No current was
observed in any of the conduits, but as they relate to an
abandoned freshwater regime, this is not surprising. The presence
of these solution conduits at a preferred horizon in a uniformly
soluble lithology argues for a stillstand in sea level at -105 m
for a minimum of a few thousand to tens of thousands of years.
The abundance of the conduits suggests high discharges in a
competitive manner, and this has implications for rainfall volumes
during the time of conduit formation. Unlike the larger platforms
to the west, San Salvador experiences a minimal increase in
meteoric catchment area as sea level falls, thus allowing boundary
conditions to be placed on the source of the discharge of the
conduits.

174

The location of two conduits at -12 5 m on Dive IV has the
same implications as conduits at -105 m. The paucity of the data
prevents a conclusive argument for a low sea level stillstand at
-125 m.

The preliminary reconnaissance made with the Johnson-Sea-Link
I is very encouraging. Conduits have been located, and at
apparently preferred depths. Two goals remain to be addressed:
first, to continue reconnaissance and prove that the -105 m and
-125 m levels persist, and to look for other possible levels;
second, while past low sea level elevations have been identified,
they haven't been placed in a chronological framework. The
surficial work on San Salvador was able to date the high sea level
solution conduits by forming a time window between wall rock age
on one hand, and subaerial precipitate (stalagmites) age on the
other. A submersible based sampling capability needs to be
developed that would allow the collection of submerged conduit
wall rock and conduit contents for dating purposes.

Manned undersea reconnaissance has proven feasible for the
location of solution conduits produced at past lower sea levels.
Further work should resolve the preferred conduit positions, and
locate conduits that would be prime sites for sample collection
for dating purposes. Submersibles allow access to the lower
ranges of Pleistocene sea level fluctuations that are difficult to
reach through SCUBA diving.

ACKNOWLEDGEMENTS

The authors wish to acknowledge the support of the Harbor
Branch Foundation during this work, especially the staff and crew
of the R/V Johnson and the Johnson-Sea-Link I. The College Center
of the Finger Lakes Bahamian Field Station, Dr. Donald T. Gerace,
Director, provided critical access and services for the research
program. The College of Charleston and Murray State University
provided additional logistical support and services.

LITERATURE CITED

Bloom, A.L., W.S. Broecker, J.M.A. Chappel, R.K. Matthews, and
J.K. Mesolella. 1974. Quaternary sea level fluctuations on
a tectonic coast: New U/Th dates from the Huon Peninsula,
New Guinea. Quat. Res. 4: 184-205.

Boardman, M.R., L.A. Dulin, and R.J. Kenter. 1983. High stands
of sea level: Rhythmic deposition of bank-derived carbonate
sediment in the deep periplatform environment. Geol. Soc.
Amer. Abstr. Prog. 15: 528.

Carew, J.L., and J.E. Mylroie. 1983. New estimates of late
Pleistocene sea level from San Salvador, Bahamas. Geol.
Soc. Amer. Abstr. Prog. 15:538.

Carew, J.L., J.E. Mylroie, J.F. Wehmiller, and R.S. Lively. 1984.
Estimates of late Pleistocene sea level from San Salvador,
Bahamas. In: J.W. Teeter (ed.), Proc. of the 2nd Symp.
of the Geology of the CCFL Bahamian Field Station, p.
153-175. San Salvador Island, Bahamas.

175

Cronin, T.M. , B.J. Szabo, T.A. Ager, J.E. Hazel, and J. P. Owens.

1981. Quaternary climate and sea levels of the U.S.

Atlantic coastal plain. Science. 211: 233.
Jennings, J.N. 1971. Karst. MIT Press, Cambridge, MA.
Mullins, H.T., and G.W. Lynts. 1977. Origin of the northwest

Bahama platform. Geol. Soc. Amer. Bull. 79: 993-1006.
Mylroie, J.E. 1983. Caves and karst of San Salvador. In: D.T.

Gerace (ed.), Field Guide Geol. of San Salvador Island, p.

67-96. CCFL Bahamian Field Station, San Salvador Island.
Palmer, R. 1982. Blue Holes '81, The preliminary report of the

British cave diving expedition. Bahamas Natur. 6: 7-14.
Palmer, R. 1984. Grand Bahama '83, Blue Hole diving in eastern

Grand Bahama. Caves and Caving 23: 10-13.
Williams, D.W. 1979. Nature's reversing siphons. Bahamas

Natur., Winter 1978: 6-7.

NOAA Symp.Ser. for Undersea Res. 2(2), 1987 177

THE BLAKE ESCARPMENT — A PRODUCT OF
EROSIONAL PROCESSES IN THE DEEP OCEAN

William P. Dillon and Page C. Valentine

U. S. Geological Survey

Woods Hole, Massachusetts 02543

Charles K. Paull
Scripps Institute of Oceanography
La Jolla, California 92037

ABSTRACT

The Blake Escarpment, east of Florida, is a steep submarine
cliff that extends from water depths of about 1000 to 5000 m and
forms the eastern boundary of the Blake Plateau. An initial
hypothesis that the modern escarpment was formed by accretion and
erosional retreat was based solely on interpretations of seismic
profiles. However, diffractions in the seismic record obscured
the morphology of the cliff face. Dives in the submersible DSRV
ALVIN, at locations where multichannel seismic reflection profiles
cross the escarpment, have resulted in a new understanding of the
feature's development. Observations from the submersible
indicated that the slope of the escarpment approached 80°-90° in
many areas, and that exposed rocks are Lower Cretaceous limestone
that was deposited in the quiet interior of a carbonate bank.
Erosional agents that presently are modifying the cliff face
include strong currents, abrasion by biogenic sand, and unloading
that results in extensive jointing and fragmenting of the rock.
It is estimated that the cliff face has retreated as much as 15 km
since its formation by accretion through reefal upbuilding.

INTRODUCTION

The work described here represents an effort to use a
research submersible, DSRV ALVIN, to confirm or deny a hypothesis
based on geophysical data concerning the formation of the Blake
Escarpment, a steep cliff on the sea floor east of Florida (Figure
1) . The typical continental margin is characterized by a
relatively flat continental shelf and, to seaward, a somewhat
steeper continental slope and gently sloping rise. Off the
southeastern United States, the continental slope (Florida-
Hatteras slope; Figure 1) is interrupted at about 600-m depth by
the broad, flat Blake Plateau. The plateau is terminated to
seaward by the Blake Escarpment, which descends steeply from about
1000 m down to almost 5000 m. This escarpment, if exposed, would
be one of the most spectacular mountain fronts on earth.

The origin of the Blake Escarpment has been a puzzle.
Naturally, its steep, linear nature might suggest a possible
structural (faulted) origin in some tectonic settings, but this is
inconsistent with our knowledge of development of trailing-edge

178

Figure 1. Bathymetry of the continental margin off the
southeastern United States and locations of dive sites shown by
circles. Depths are in meters.

179

continental margins, such as the U.S. eastern margin, where broad
regional subsidence without much active faulting is the dominant
tectonic style. Recent interpretations have focused on two
alternatives: (1) a simple accretional model, in which the
escarpment is formed dominantly by reefal upbuilding (Dillon et
al., 1979; Sheridan et al., 1981); or (2) an accretional-
erosional model, in which the escarpment is formed by major
accumulation of carbonate platform rocks followed by extensive
erosional retreat (Paull and Dillon, 1981) .

To help resolve the problem, we made ten submersible dives
from the top of the escarpment down to ALVTN's maximum dive depth
of 4,000 meters, completing three transects of the escarpment at
sites A, B and C (Figure 1) . Seismic-reflection profiles along
these three transects and extending to the east and west are shown
in Figures 2, 3, and 4, respectively.

METHODS

The multichannel seismic reflection profiles were collected
by Teledyne Exploration Company, under contract to the U.S.
Geological Survey. The seismic source consisted of four 540-in
(8850-cm3) airguns fired simultaneously. The seismic streamer was
3 600 m long and contained 48 recording sections; the 24 sections
nearest the ship were each 100 m long. The data from each section
were recorded separately and subseguently were computer-processed
and stacked to create the profiles (Figures 2, 3, and 4).

The submersible, DSRV ALVIN, is highly maneuverable and, at
the time we used it, had a maximum operating depth of 4000 m.
Observation is afforded by three ports, one for the pilot and one
each for the two scientific observers. Internal observer-hand-
held cameras are connected to external strobe lights (Figures 9
and 11) and external automatic cameras take photographs at
selected intervals (Figures 5, 6, 7, 8 and 10). An external video
camera was used to tape the entire dive. Samples of rock were
obtained using the submersible 's two mechanical arms with claws,
one electrically powered (more maneuverable) and one hydraulically
powered (more powerful) . The claws were also used to hold small
corers and scoop samplers for sediment sampling.

RESULTS

Geophysical Data and Interpretations

Prior to diving onto the escarpment, hypotheses explaining
the escarpment's development were based on geophysical data and a
few scattered samples of dredged rock. The geophysical studies
were based on acoustic data (echo sounder and sidescan-sonar data
and seismic-reflection profiles) as well as on magnetics and
gravity data. The acoustic data are extremely difficult to
interpret in an area of steep slopes such as the Blake Escarpment,
as shown by Figure 2, which illustrates the difficulty of
identifying escarpment features in a seismic profile (and in most
echo sounder profiles, as well) . The profile shows the outer
Blake Plateau on the left and the deep sea floor to the right.

180

¥RQFIL_£ ?D^

Figure 2. Multichannel seismic reflection profile passing east-
west through dive site A (Figure 1) . Four dives were made here.
The vertical scale is in travel time of sound and therefore the
vertical scale varies, depending on velocity of media. A depth
scale based on water velocity is shown on right side of figure.
Vertical exaggeration, based on water velocity, is 4:1.

The steep escarpment is hidden behind a set of hyperbolic
reflections that appear because the profiling system does not
focus its sound rays downward, but rather records echo returns
from many directions. The first return comes from the nearest
reflecting point, whether it is directly beneath the ship in
front, behind, or off to the side. If the ship is slightly to
seaward of a steep cliff, the acoustic returns from the cliff will
obscure the sea floor beneath the ship and echoes from the upper
part of the escarpment will obscure the lower part. Therefore, it
is impossible to examine a steep slope by seismic means using
ordinary surface-towed equipment. In order to see the Blake
Escarpment, we had to dive and, in effect, maneuver the sub inside
the displayed hyperbolic envelope of echoes. Despite the
difficulties in interpretation, the seismic profiles do provide
evidence that suggests major erosional retreat of the Blake

181

Escarpment. First, even though we could not make exact
measurements, it was clear to us that the steepness of the slope
exceeded values that could possibly be created by reefbuilding or
any other accretionary process over such a vertical range (4 000
m) . We also discovered a buried bench within the sediments
seaward of the base of the escarpment (Figures 2 and 3) . The top
of the bench was continuous with an erosional horizon in the
deepsea deposits, and strata are truncated at the bench surface.
These facts suggest that the bench represents a cut into the old
platform edge that removed a triangular section of rock and that
the toe of the slope has retreated at least 12 km at the site of
Figure 2, suggesting that erosion is active now, as well as having
operated in the Oligocene (the probable age of the bench;
Tucholke, 1979) . The profiles also show no pile of debris at the

m^n

REEF

PROFILE TD-4

Figure 3. Multichannel seismic reflection profile passing east-
west through dive site B (Figure 1) . Three dives were made here.
Vertical exaggeration in water is 4:1.

foot of the escarpment (Figures 2, 3, 4), but rather a deepening
toward the escarpment, again suggesting active erosion. Finally,
structures are truncated at the escarpment. The profile in Figure
4 is somewhat less difficult to interpret because the slope is
less steep. It shows a truncated reef (inferred from seismic
pattern) at the top of the escarpment and truncated reflectors
part way down.

182

Observations from Deep Dives

Dive observations showed that much of the escarpment was
nearly vertical, particularly at site A where the escarpment
slope appeared to average about 80° over the depth range of the
dives (Figure 2). This is illustrated by Figure 5, which is a
photograph taken along a near-vertical outcrop that shows
octocorals growing horizontally outward from the wall.

The environments of deposition that are indicated by studies
of rocks sampled by ALVIN from the cliff provide support for the
hypothesis of major erosional retreat. These rocks have been
formed from sediments that were deposited in quiet waters of a
carbonate bank interior, like the present Bahama Banks, commonly
in shallow, in some cases, intertidal depths. Rocks that are
formed in reefs or bank-edge structures, built where wave activity
is at the perimeter of a carbonate bank, show the effect of a
turbulent environment. No doubt, the seaward side of the
carbonate platform was characterized by such bankedge features,
and the presence of bank interior facies, sampled at the present
cliff, implies that considerable rock was removed by erosion.

TRUNCATED REEF

PROFILE TD-3
5 KM

Figure 4. Multichannel seismic reflection profile passing east-
west through dive site C (Figure 1) . Three dives were made here.
Vertical exaggeration in water is 4:1.

Rocks in the cliff face were found to be extensively jointed
(Figures 6 and 7) , probably resulting from an uneven release of
load (Nichols, 1980) . In this case, an uneven release of pressure
apparently is being caused by removal of rock to seaward of the
present cliff. Thus, development of joints is the product of

183

erosion, but it also facilitates erosion by causing fragmentation
of the massive rock. Figure 6, is a horizontal view of an outcrop
face, whereas Figure 7 is a downward view of stratum that has been
exposed by erosion, and fractured into flagstones along joints.
Often, joint blocks collapse after erosion has removed support,
and jointing and erosion produce a stepped cliff face (Figures 8
and 9) .

In some cases, erosion is facilitated by large variations in
lithification. For example, Figure 10 shows several layers of
light-colored, soft, Cretaceous lime mud interlayered with hard,
brittle, dark-coated limestone rock of the same age. The soft
layers can be eroded away easily, removing support for rock above
them, and resulting in collapse.

Erosion by mechanical means reguires currents and abrasives
to grind away the rock. We experienced currents up to
approximately two knots along the cliff face, which caused
considerable difficulties in maneuvering ALVIN and damage to the
sub when it was swept into outcrops. The strong currents
apparently employ as abrasive the modern biogenic sand, commonly
formed of pteropod remains, that accumulates in areas of reduced
current (note lower part of Figure 9) .

Figure 5. Photograph along a vertical face at dive site A.
Height of cliff is about one meter.

184

In addition to the erosion by mechanical processes resulting
from water currents, erosion by chemical and biological processes
may be active. Because the solubility of calcium carbonate
increases with increasing water depth, the lack of a pile of
debris at the foot of the escarpment, suggested by seismic
profiles, may be related to chemical corrosion, which would be
enhanced by the high current speeds. The foot of the escarpment

"* /%

"w"

Figure 6. Photograph showing jointed vertical outcrop. Width of
photograph is about 2-3 meters.

(at 5 km depth) was below the diving capability of ALVIN.
However, where we observed the cliff above 4 km, the rock
fragments did not show rounded edges, as would be expected with
chemical solution, but rather very angular corners, more
consistent with a mechanical breakdown (Figure 6, 7, 8, 9, 10).
Grooves, pits and borings in the rock face (Figure 11) may be
caused by activity of modern organisms, particularly sponges, or
they possibly might result from exhuming of burrows formed during
sediment deposition and initially filled with less resistant
sediment.

185

S 6. C 0

6a is

Figure 7. Photograph looking down on a horizontal stratum jointed
into flagstones. Width of outcrop is about 2 meters.

se.o

00. '

s ->

Figure 8. Photograph along a stepped outcrop. Height of outcrop
is about one meter.

186

Figure 9. Collapsed joint-bounded block about one meter in
length. Note pteropod sand at bottom of photograph. Block is
about one meter long.

Figure 10. Alternating layers of hard, lithified limestone coated
with dark ferromanganese and light unlithified lime mud of the
same age. The mud is relatively easily eroded. Photograph shows
about one meter, vertically.

187

Figure 11. Close-up photograph of a small reentrant in cliff
taken through observer's port while ALVIN was in contact with the
face of the Blake Escarpment. Borings in rock and grooves in
upper part of figure are about one centimeter in diameter. White
objects are siliceous sponges. Width of photograph approximately
1/2 meter.

SUMMARY

By combining the echo-sounder, seismic profiling, and
sidescan-sonar data with our observations from the submersible, we
now have a very precise concept of the appearance of the Blake
Escarpment. This represents a considerable advance in our
knowledge of the nature of the sea floor and it has been
summarized in a physiographic diagram (Figure 12).

Our initial hypothesis that the Blake Escarpment was formed
by extensive erosional retreat of a submarine cliff face is
strongly supported by observations and samples that were provided
by submersible dives. Furthermore, these were results that only
could be obtained by submersible operations.

Some of the evidence that supports the hypothesis of erosion
and cliff retreat of the Blake Escarpment is summarized in Figure
13. Seismic data show the buried bench, the truncated strata at

188

Physiographic diagram of the Blake Escarpment
off Southeastern United States

Tau Rho Alpha. William P Dillon, Patricia Forrestel, Jeff Zwinakis
1981

Figure 12. Physiographic drawing of the Blake Escarpment. This
is a presentation of the appearance of the escarpment on the basis
of echo-sounder profiles, seismic-reflection profiles, a sidescan-
sonar survey, and observations from a submersible. Diagram
created by Tau Rho Alpha, Patricia Forrestel and Jeff Zwinakis.

the sea floor and escarpment, and the moat at the foot of the
escarpment, and give some impression of the steepness of the
cliff. Submersible work confirmed the steepness of the face and
showed that it actually is much steeper than we had estimated.

189

KILOMETERS

6 8 10 12 14 16 18

i 1 1 1 1 1 1-

—r-

-J

LAG00NAL

FACIES

EXPOSED

EVIDENCE FOR EROSION AT BLAKE ESCARPMENT

-TRUNCATED PLATFORM STRATA
/ /-STEEPNESS -ANGLE OF REPOSE
* / /-HO TALUS SLOPE
/ /^MOAT AT FOOT OF ESCARPMENT

TRUNCATED STRATA NEAR SEA FLOOR
(SECOND MAJOR PHASE OF EROSION)

BURIED BENCH WITH TRUNCATED STRATA -\
CONTINUOUS WITH MAJOR DEEP-SEA UNCONFORMITY J

Figure 13.
Escarpment.

Summary of evidence for erosion of the Blake

Submersible sampling revealed the presence of rocks representative
of deposition in the quiet interior of a carbonate bank. Perhaps
most important, diving to the escarpment presented evidence on the
processes of deep-sea erosion. We experienced currents much
stronger than anticipated, observed modern biogenic sand which
could provide the abrasive to erode rock, and saw the very
extensive jointing that clearly is having a significant effect by
fragmenting the rock. We have emphasized the role of physical
erosion because evidence for that type seems to be the most
obvious in the observations. Chemical corrosion of limestone,
which becomes progressively more significant as depth increases,
may be dominant below our range of observations. The blocky,
angular nature of the rock fragments suggests that solution, which
would tend to round the corners of blocks, is not dominant down to
4000 m depth. However, the steepness of the escarpment and moat
at its base suggest that erosion may be concentrated at the base
of the cliff, where chemical effects may become more significant.
Obviously, we need to work at these depths, beyond the 4000 m
operating limit of ALVIN.

Two major questions remain: (1) If erosion is more effective
at greater depths, as it seems to be, how do the processes change
with depth? (2) What are the relative importance of physical,
chemical and biological erosion at all depths?

190

LITERATURE CITED

Dillon, W. P., C.K. Paull, R.T. Buffler, and J. P. Fail. 1979.

Structure and development of the southeast Georgia Embayment

and northern Blake Plateau: Preliminary analysis. In: J.S.

Watkins, L. Montadert, and P.W. Dickerson (eds) , Geological

and Geophysical Investigations of Continental Margins.

American Association of Petroleum Geologists, Memoir 29:27-

41.
Nichols, T.C., Jr., 1980. Rebound, its nature and effect on

engineering works. Quarterly Journal of Engineering Geology

13:133-152.
Paull, C.K., and W.P. Dillon. 1980. Erosional origin of the

Blake Escarpment: An alternative hypothesis. Geology 8: 53 8

-542.
Paull, C.K. and W.P. Dillon. 1981. Erosional origin of the Blake

Escarpment: An alternative hypothesis — Reply. Geology

9: 339-341.
Sheridan, R.E. 1981. Erosional origin of the Blake Escarpment:

An alternative hypothesis — Comment. Geology 9: 338-339.
Sheridan, R.E., J.T. Crosby, K.M. Kent. W.P. Dillon, and C.K.

Paull. 1981. The geology of the Blake Plateau and Bahamas

region. In: The Geologic Atlas of the North American

Borderlands. Canadian Society of Petroleum Geologists,

Memoir 7:487-502.
Tucholke, B.E. 1979. Relationships between acoustic stratigraphy

and lithostratigraphy in the western North Atlantic Basin.

In: B. E. Tucholke, P.R. Vogt, et al . (eds.), Initial

Reports of the Deep Sea Drilling Project, Vol. XLIII: 827-

846.

NOAA Symp. Ser. for Undersea Res. 2(2), 1987 191

BIOLOGICAL AND GEOLOGICAL PROCESSES AT THE SHELF EDGE
INVESTIGATED WITH SUBMERSIBLES

John K. Reed and Charles M. Hoskin
Harbor Branch Oceanographic Institution
5600 Old Dixie Highway
Fort Pierce, Florida 33450 USA

ABSTRACT

Studies of living reefs along the shelf edge off eastern
Florida and the Bahamas suggest the interrelation of physical,
biological, and geological processes. JOHNSON-SEA-LINK
submersibles were used to sample corals and sediment with a
manipulator or by lock-out diving. Videotape and 3 5 mm cameras,
CTD system, and transmissometer were used to document the dives.
Sediment traps, light meters, time-lapse camera, thermographs, and
current meters were deployed and recovered. A 222 km long reef
system of discontinuous pinnacles capped with living and dead
Oculina coral was studied off Florida. Upwelling may contribute to
growth and community structure of the reef system. Growth rates of
the coral averaged 1.6 cm/yr and the coral harbors diverse faunal
assemblages. Each pinnacle produces carbonate sediment and traps
mud sized particles. Sand and gravel particles are not transported
far from the reefs. On the margin of Little Bahama Bank sediment
traps were also deployed to study sediment transport through reef
notches from shallow to deep water. Average sediment flux over the
edge of the wall was 1.34 kg notch-1 yr-1.

INTRODUCTION

Within the last decade, the submersible has proved to be an
invaluable research tool for the study of biological, geological,
and physical processes on the continental shelf and slope, in
midwater, and in the deep sea. These vehicles enable the
investigator to observe directly and to sample discrete
microhabitats; this is not possible with remote sampling from
surface vessels.

Studies of living reefs along the shelf margin off eastern
Florida and in the Bahamas suggest the interrelationships among
physical, geological, and biological processes. This paper
provides a summary of some of these studies on the shelf edge
utilizing the JOHNSON-SEA-LINK submersibles.

MATERIALS AND METHODS

One study area was the Oculina coral banks at the shelf edge
off central eastern Florida. This high latitude reef system
consists of discontinuous prominences that are capped with living
and dead colonies of the scleractinian Oculina varicosa Lesueur,
1820. Published data on these reefs which will be summarized
herein consist of research concerning the structure and
distribution of the Oculina banks, their associated fauna, the
physical environment, and sedimentary processes. One particular

192

study site within this area was Jeff's Reef (27°32'N, 79°58'W), a
16-m high bank, approximately 1000 m in circumference, that has an
extensive cover of contiguous, living coral.

Study areas in the Bahamas were at the shelf margin off Black
Rock, Little Bahama Bank and San Salvador Island. Objectives at
the Bahamian sites were to determine rates of sediment production
by various biogenic sources, to identify sediment transport
pathways, and to determine rates of sediment flux from the shelf
to the slope.

The JOHNSON-SEA-LINK (J-S-L) I and II submersibles were used
for sampling, deploying experiments and recorders, lockout diving,
and photographic reconnaissance. These submersibles are capable
of diving to 800 m for a duration of 3 to 5 hours and consist of
1.5-m diameter acrylic sphere, which carries a pilot and one
scientist, and an aluminum dive chamber, which carries one
scientist and a dive tender. The J-S-L1 s were fitted with some or
all of the following equipment: two Benthos cameras (each with
30-m rolls of 35 mm film) ; 3/4 inch color video tape recorder with
pan and tilt; manipulator arm with 19x19 cm clamshell grab, jaws
and suction collecting tube; 12-bucket rotating sample basket;
fish poison dispenser; conductivity-temperature-depth (CTD)
recorder; transmissometer ; current meter; and scanning sonar.
Precision tracking of the submersible is presently plotted on the
mother ship (R/V JOHNSON or R/V SEA DIVER) with a Honeywell
digital acoustic positioning system and an Epsco plotter. Loran C
and satellite navigation are used for ship positioning.

RESULTS AND DISCUSSION

Distribution of Oculina Banks

An initial determination of the distribution of the shelf-
edge Oculina banks off eastern Florida was compiled from
transcripts and film from over 13 5 submersible dives, 57 dredge
and trawl records, and numerous echo-sounder and side-scan-sonar
recordings (Avent et al., 1977; Reed, 1980; Thompson and
Gilliland, 1980) . This bank system roughly parallels the 70-80 m
bathymetric contour from approximately 27°32'N to at least
28°59'N and possibly as far north as 30°. It consists of dozens
and possibly hundreds of isolated prominences.

The prominences are steep-sloped (30-45°) structures, with
maximum relief of 25 m and bases a few hundred meters in
diameter. Numerous knolls with less than 5-m relief also occur in
this region. Some of the prominences are covered with massive
thickets of contiguous, living colonies of Oculina varicosa which
grow 1-2 m in height. Maximum coral growth is usually on the
south side of the prominences, facing into the Gulf Stream. Other
prominences are covered completely with dead coral rubble or
standing, dead colonies of Oculina. Prominences with all dead
coral have been found within a few hundred meters of those with
living coral, and the causes of death are unknown. Isolated
colonies and thickets of living Oculina also occur on relatively
flat sandy bottom among the prominences. A 92 nm2 area of the
Oculina bank system bounded by 27°30'N and 27°53'N has been
designated as a protected habitat within the Coral and Coral Reefs
Fishery Management Plan (Gulf of Mexico and South Atlantic Fishery

193

Management Councils, 1982) .

Although echo-sounder records are useful to document the
physiographic features of the shelf, and side-scan-sonar can
detect hard bottom versus sand, neither technique can
differentiate between living and dead Oculina. Thus it is
necessary for direct observation with submersibles to determine
the extent and distribution of the Oculina banks.

Physical Environment

A one to two year data base of near-bottom temperatures,
currents, light levels, and sedimentation rates were collected at
Jeff's Reef (80 m) with equipment deployed and recovered from the
submersibles. The shelf-edge Oculina banks occur in a region of
cold-water upwelling. Yoder et al. (1983) reported that upwelling
occurred along the southeast U.S. 50% of the time from November to
April. Our thermographs recorded a range of temperature from
7.4°C to 26.7°C and an average of 16.2°C (Reed, 1981). Cold water
upwelled periodically from the Florida Straits with each event
lasting 1-4 weeks and temperatures rapidly dropped below 10°C.
During upwelling periods, levels of nitrates, phosphates and
chlorophyll a increased by nearly an order of magnitude (R.M.
Gibson, personal communication) .

Although surface currents are usually strong and northerly
from the Gulf Stream, the bottom currents have strong E-W, north,
and south components (Hoskin et al., in press). Average near-
bottom current speed was 8.6 cm sec-1 but occasionally was in
excess of 75 cm sec-1 (Hoskin et al., 1983). Salinity was stable,
ranging from 35.7 to 36.4 ppt (Reed, 1981).

Licor light meters recorded less than 1% of surface light at
the 80-m reef. Most living Oculina on the banks lack
zooxanthellae but some of this algae is present in the coral near
the crest of the higher prominences. Turbid bottom water often
inundates the Oculina banks reducing visibility to less than 1 m.
This turbidity appears to be caused both by resuspension of shelf
sediment and by plankton blooms resultant from the upwelling.
Sedimentation rates averaged 53 mg cm"2 day _1 (Reed, 1981) .

Ecological Studies

The Oculina biotope supports dense and diverse invertebrate
and fish communities. A preliminary assessment of the
macroinvertebrates (>0.5 mm) was made during a one year study in
which 2-4 coral colonies (147-2715 g dry weight) were collected by
scuba and lockout scientist-divers every 2-3 months at four reef
sites (6, 27, 42 and 80 m) . A total of 42 Oculina samples yielded
over 2 0,000 individual invertebrates and were species-rich in
mollusks (230 spp.), decapods (50 spp .), amphipods (47 spp.),
echinoderms (21 spp.), and polychaete worms (23 families). Also
common were nemertine and sipunculan worms, pycnogonids, tanaids,
isopods, ostracods and copepods.

The shelf-edge Oculina (80 m) had a greater diversity of both
decapods (Reed et al., 1982) and mollusks (Reed, 1983) than the
inner and midshelf reef sites. The macroinvertebrate community
composition and structure was distinctly different between the
inner- and outer-shelf reef sites. Detritivores were the most
abundant type of decapod at the shelf edge, whereas for the

194

inner and midshelf sites, mollusks, carnivores and coral-eating
species dominated. Upwelling may provide an essential supply of
nutrients and plankton to the shelf -edge Oculina community (Reed,
1983) .

Other studies utilizing J-S-L submersibles on the Oculina
banks resulted in descriptions of new species, subspecies, and in
situ behavioral patterns of echinoderms (Miller and Pawson, 1979;
Pawson et al., 1981; Pawson and Miller, 1983; Miller, 1984;
Hendler and Miller, 1984a, b) .

Dense populations of commercially and recreationally
important fishes occur on the Oculina banks (Figure IB) . Over 7 0
species of fishes have been identified (R.S. Jones and R.G.
Gilmore, personal communication, Marine Science Institute,
University of Texas, Port Aransas , TX 78373) including scamp,
gag, speckled hind, snowy grouper, black sea bass, porgies, and
snappers.

Figure 1. A) Lockout diver-scientist measures growth of Oculina
coral at shelf-edge reef (80 m) . B) Aggregation of fishes (scamp,
snowy grouper, and drums) at base of Oculina reef (75 m) . C)
Sedimentation trap deployed with submersible ' s manipulator arm at
base of wall (90 m) off Little Bahama Bank. D) Coral debris and
Halimeda sand and gravel in groove of steep slope (464 m) off
Little Bahama Bank.

195

Dense schools of anthiids (Hemanthias vivanus) congregate
over and in the coral. Although H. vivanus is considered
planktivorous, they have been observed (JKR) picking small food
items from among the branches of Oculina. Schools of amber jack
commonly travel among the banks. Spawning by the squid (Illex
oxvgonius) and mating by the roughtail stingray (Dasyatis
centroura) have also been observed (Reed and Gilmore, 1981) .

From submersible observations, grouper and snapper
populations do not appear stable on any one reef but apparently
travel among the banks and tend to prefer areas with living coral
rather than dead coral rubble. Atkinson and Targett (1983)
reported that greater fish densities were found on the outer shelf
between Cape Canaveral, Florida, and Cape Hatteras, North
Carolina, in zones of upwelling. The exact relationship and
importance of the coral-associated invertebrate community to the
fish community remains unknown. The influence of upwelling upon
the entire Oculina bank system is also unknown.

Geological Processes - Oculina Banks

The substrate on which the Oculina banks have developed may
be relict oolitic limestone ridges formed during the Holocene
transgression (Macintyre and Milliman, 1970) . The thickness of
the coral rubble, sand and mud matrix which has built upon the
rock base of the prominences is unknown. A lockout diver (JKR)
was able to probe the sediment near the crest of Jeff's Reef with
a 1/4 inch rod to a depth of 3.7 m without hitting bedrock. Rock
outcrops are not visible on the majority of the prominences on
which we have dived; however, rock pavement is often visible in
small patches in the flat bottom surrounding the reefs. Rocks that
we have collected from the base of several reefs consisted of
oolitic, conquinoid, and pelletoid limestone. In addition, one
sample collected at a reef base (88 m) was an Oculina biolithite,
consisting of lithified coral rubble and mud.

Although we know from in situ measurements that the linear
growth rate of Oculina branches averaged only 1.6 cm yr-1 at 80 m
(Reed, 1981) , the accretion rate of the banks is unknown (Figure
1A) . One piece of Oculina rubble that was recovered from a depth
of 8-12 cm in a short core taken by a lockout diver near the crest
of Jeff's Reef was radiocarbon dated at 480 + 70 yr B.P. (Hoskin
et al., in press). Unfortunately, standard sub-bottom profiling
is not suitable and deeper coring is not economically practical to
determine the thickness of the coral and mud matrix on these
prominences.

A detailed study was made of the surficial sediments at
Jeff's Reef and the surrounding shelf and slope (Hoskin et al., in
press) . Non-reef samples were collected with a Smith-Mclntyre
grab from a surface vessel and the reef samples were collected
with a clam-shell grab attached to the manipulator arm of the
J-S-L submersible. The surficial reef sediments consisted of
modern carbonate mixed with relict carbonate and quartz. There
was more gravel in reef sediments (mean % = 2 3.8) than surrounding
non-reef sediments (0.9-8.5%) and reef gravel consisted mostly of
Oculina branches. Reef sand was mostly quartz (26.8%), mollusk
shells (23.6%), foraminiferans (12.2%), barnacles (7.3%), and
pellets (6.7%), along with carbonate rock fragments, echinoderm

196

fragments, coral, and coralline algae. In general, the reef sand
contained significantly more barnacles and coral, and less ooids
and pellets than surrounding non-reef sediments.

The reef sediment also contained a greater percentage of mud
(14.3%) than nearby shelf sediments (4-8%). Some of this mud may
be trapped by the reef from the water column through a baffling
effect, and part is generated by microborers. Preliminary studies
by the authors on bioerosion of Oculina indicate that attack is
dominated by clionid sponges, 7 species of bivalves, eunicid
polychaetes, sipunculans, and a boring cirriped. When weakened by
bioerosion, the Oculina colonies become more susceptable to
breakage by peak currents. In a tow-tank test, Oculina branches
showed breakage at current speeds of 14 0 cm sec-1 (Hoskin et al.,
in press) . The coral rubble is then subject to mechanical
abrasion resulting in further production of gravel, sand, and mud
size particles (Hoskin et al., 1983).

Shelf Margin Sediment Transport

Studies on the Oculina banks showed that currents may not be
strong enough to transport coral gravel far from the reefs but
export of coral sand is detectable (Hoskin et al., in press).
These studies have not yet addressed whether the Oculina banks act
as a barrier to the transport of sediment from the shelf to the
slope as suggested by Emery (1968) . However, transport of shelf
sediment is part of several on-going studies in the Bahamas.
Rates of erosion by chemical solution, physical abrasion, and
bioerosion on the shelf have been measured by CMH. Bioerosion was
found to be 2 0 times more intense than the other processes. One
study showed that a population of 92 x 103 boring echinoderms
(Echinometra lucunter) off Black Rock (400-m long) produced 9 tons
of sediment per year; associated rock infauna produced an
additional 6 tons yr-1 (Hoskin and Reed, 1985) . The transport of
the shelf sediment to deeper environments occurs by two main
modes: 1) mud is transported in suspension over the shelf break,
and 2) sediment moves through notches that cut through the shelf -
edge reefs which otherwise act as barriers to sediment transport.
This carbonate sediment is deposited in submarine aprons which is,
recently, of interest to petroleum geologists.

We measured the rate of sediment transport over the shelf
margin by deploying sediment traps with the submersibles in
notches at the top of the shelf break (38-45 m) , on ledges near
the base of the vertical wall (80-90 m) (Figure 1C) , and on inter-
groove areas on the slope (464 m) (Hoskin et al., 1986 ). Initial
results indicate that there is a decrease in sediment flux rates
between the shelf margin and the base of the wall, indicating that
some of the sediment is lost from surficial transport and is
deposited as internal sediment. Average sediment flux through the
bank margin was 1.34 kg notch _1 yr -1. The grooves on the deep
slope contained much coarse grained sediment of shallow water
origin, primarily Halimeda plates and also dead coral colonies up
to 1 m diameter (Figure ID) . This downslope transport undoubtedly
produced these grooves in the bedrock of the slope.

197

Future Studies

The above studies begin to unravel the complexities of the
interrelationships among physical, geological, and biological
processes. Physical factors such as current and wave surge are
important for sedimentary processes such as bedload transport,
sedimentation, abrasion, and breakage of coral. Other physical
factors such as upwelling may be crucial for the maintenance of
the shelf -edge Oculina banks and associated fauna by supplying
nutrients and the concommitant plankton blooms. The physiographic
features on the shelf-edge reefs affect sedimentary processes by
trapping suspended sediment and damming sediment, which restricts
transport off the shelf. The diversity of the faunal community at
the shelf edge is also related to these geological features.

Some objectives for future submersible studies are:

1) What is the extent of the living versus dead Oculina
reefs at Florida's shelf edge?

2) What agent (s) have caused the extensive areas of dead
Oculina?

3) Is upwelling a major source of nutrients supporting the

Oculina reefs and associated fauna, and what are the
pathways of energy transfer?

4) What densities of commercially and recreationally
important fish populations occur on the Oculina banks,
and how are these fishes distributed in relation to live
versus dead reefs?

5) Are the physiographic features of the Oculina banks
primarily due to a buildup of coral debris and mud matrix
or a result of antecedent rock structures capped with
only a thin veneer of coral rubble and mud?

6) What are the pathways and processes of deep-sea apron

formation at the margin of carbonate banks, and what is
their potential as hydrocarbon reservoirs?

ACKNOWLEDGEMENTS

We thank the officers and crews of R/V JOHNSON, R/V SEA

DIVER, and JOHNSON SEA-LINK I and II for their invaluable

assistance at sea. This is Contribution No. 395 from Harbor
Branch Oceanographic Institution, Inc.

LITERATURE CITED

Atkinson, L.P., and T.E. Targett. 1983. Upwelling along the
60-m isobath from Cape Canaveral to Cape Hatteras and its
relationship to fish distribution. Deep-Sea Res. 30: 211-
226.

198

Avent, R.M. , M.E. King, and R.H. Gore. 1977. Topographic and
faunal studies of shelf-edge prominences off the central
eastern Florida coast. Int. Revue ges. Hydrobiol. 62: 185-
208.

Emery, K.O. 1968. Shallow structure of continental shelves and
slopes. Southeastern Geol . 9: 173-194.

Gulf of Mexico and South Atlantic Fishery Management Councils.
1982. Fishery management plan, final environmental impact
statement for coral and coral reefs of the Gulf of Mexico and
South Atlantic. NOAA, Dept. of Commerce.

Hendler, G., and J.E. Miller. 1984a. Ophioderma devanevi and
Ophioderma ensiferum. new brittlestar species from the
western Atlantic (Echinodermata: Ophiuroidea) . Proc. Biol.
Soc. Wash. 97: 442-461.

Hendler, G., and J.E. Miller. 1984b. Feeding behavior of
Asteroporpa annulata, a gorgonocephalid brittlestar with
unbranched arms. Bull. Mar. Sci. 34: 449-460.

Hoskin, CM., and J.K. Reed. 1985. Carbonate sediment
production by the rock-boring urchin Echinometra lucunter and
associated endolithic infauna at Black Rock, Little Bahama
Bank. In: M.L. Reaka (ed.), The Ecology of Deep and
Shallow Coral Reefs, pp. 151-161. NOAA Symp. Ser. Undersea
Res. 3(1).

Hoskin, CM., J.C Geier, and J.K. Reed. 1983. Sediment produced
from abrasion of the branching stony coral Oculina
varicosa. J. Sed. Petrol. 53: 779-786.

Hoskin, CM., J.K. Reed, and D.H. Mook. 1986. Production and
off bank transport of carbonate sediment, Black Rock,
southwest Little Bahama Bank. Mar. Geol. 73 125-144.

Hoskin, CM., J.K. Reed, and D.H. Mook. In press. Sediments from
a living shelf-edge coral reef and adjacent area off central
eastern Florida. Symp. S. Fla. Geol., Miami Geol. Soc.

Macintyre, I.G., and J.D. Milliman. 1970. Physiographic
features on the outer-shelf and upper continental slope,
Atlantic continental margin, southeastern United States.
Bull. Amer. Geol. Soc. 81: 2577-2598.

Miller, J.E. 1984. Systematics of the ophidiasterid sea stars
Copidaster lymani A.H. Clark, and Hacelia superba H.L.Clark
(Echinodermata: Asteroidea) with a key to species of
Ophidiasteridae from the western Atlantic. Proc. Biol. Soc.
Wash. 97: 194-208.

Miller, J.E., and D.L. Pawson. 1979. A new subspecies of
Holothuria lentiqinosa Marenzeller from the Western Atlantic
Ocean (Echinodermata: Holothuroidea) . Proc. Biol. Soc.
Wash. 91: 912-922.

Pawson, D.L., and J.E. Miller. 1983. Systematics and ecology of
the sea urchin genus Centrostephanus (Echinodermata:
Echinoidea) from the Atlantic and Eastern Pacific Oceans.
Smithsonian Contrib. Mar. Sci. 20, 15 pp.

Pawson, D.L., J.E. Miller and CM. Hoskin. 1981. Distribution
of Holothuria lentiqinosa enodis Miller and Pawson in
relation to a deep-water Oculina coral reef off Fort Pierce,
Florida. In: J.J. Lawrence (ed.), Inter. Echinoderms
Conf., p. 321, Tampa, Fl .

199

Reed, J.K. 1980. Distribution and structure of deep-water
Oculina varicosa coral reefs off central eastern Florida.
Bull. Mar. Sci. 30: 667-677.

Reed, J.K. 1981. In-situ growth rates of the scleractinian
coral Oculina varicosa occurring with zooxanthellae on 6-m
reefs, and without on 80-m banks. Proc. 4th Int. Coral Reef
Symp. 2: 201-206.

Reed, J.K. 1983. Nearshore and shelf-edge Oculina coral reefs:
the effects of upwelling on coral growth and on the
associated faunal communities. In: M. L. Reaka (ed.), The
Ecology of Deep and Shallow Coral Reefs, pp. 119-124. NOAA
Symp. Ser. for Undersea Res. 1(1).

Reed, J.K., and R.G. Gilmore. 1981. Inshore occurrence and
nuptial behavior of the roughtail stingray, Dasyatis
centroura (Dasyatidae) , on the continental shelf, east
central Florida. N.E. Gulf Sci. 5: 59-62.

Reed, J.K., R.H. Gore, L.E. Scotto, and K.A. Wilson. 1982.
Community composition, structure, areal and trophic
relationships of decapods associated with shallow- and deep-
water Oculina varicosa coral reefs. Bull. Mar. Sci. 32:761-
786.

Thompson, M. J. , and L.E. Gilliland. 1980. Topographic mapping of
shelf edge prominences off southeastern Florida.
Southeastern Geol . 21: 155-164.

Yoder, J. A. , L.P. Atkinson, S.S. Bishop, E.E. Hofmann, and T.N.
Lee. 1983. Effect of upwelling on phytoplankton
productivity on the outer southeastern United States
continental shelf. Continental Shelf Res. 1: 385-404.

NOAA Symp. Ser. for Undersea Res. 2(2), 1987 201

CONTINENTAL SLOPE PROCESSES AND MORPHOLOGY

James M. Robb and John C. Hampson, Jr,
U.S. Geological Survey
Woods Hole, MA 02543

ABSTRACT

Studies of geologic processes that shaped the Continental
Slope offshore New Jersey are based on detailed bathymetric and
geologic mapping, using conventional single-channel seismic-
reflection profiles and core samples, followed by Sea-MARC
sidescan-sonar surveys and observations from submersibles. Fine-
grained sediments were deposited during the Pleistocene over
eroded tertiary sediments and rocks. Turbidity currents left
overbank deposits in the form of intercanyon ridges and, also
canyon floors. Eocene rocks appear to have been continuously
exposed on the lower slope since the Miocene, because deposition
has been slight and episodic slides and debris flows have shed
sediments to the upper rise. Less volumetrically important
erosional processes probably include bioerosion, groundwater
sapping, and solution of carbonates. Jointing has played an
important role in structurally controlling topography of Tertiary
outcrops by guiding mass wasting and other erosional
processes.

INTRODUCTION

The nature and vigor of bottom processes are exceedingly
important to well-conceived exploitation of offshore areas, and to
oil and gas leasing in particular. In cooperation with the Bureau
of Land Management, we investigated the geologic processes that
act on the Continental Slope in an area about 45 x 45 km between
Lindenkohl and Toms Canyons (Figure 1) (Robb et al., 1981a, b,
1982; Kirby et al., 1982; Hampson and Robb, 1984).

The area is crossed by several USGS multi-channel seismic
lines (Grow et al., 1979). Eighty piston cores and several
stratigraphic test wells provided ages and lithologies that we
could use with our 900 x 1700 m grid of single-channel seismic-
reflection profiles. We obtained nearly complete coverage of mid-
range sidescan-sonar images using the Sea-MARC-1 system that
belongs to the Lamont-Doherty Geological Observatory. The Sea-
MARC 1 is a deeply-towed sidescan-sonar device that produces
acoustic images of a 5-km wide swath of sea floor. Direct
observations of the sea bottom were made during 14 dives in
research submersibles.

This paper discusses the geologic background of a segment of
the slope and the processes that formed the present surface. We
point out that the landscape has resulted from many processes
whose rates have varied with time, and that any description of
those processes must be understood in terms of geologic history as
well as present-day rates of activity.

202

HUDSON
CANYON

AREA OF STUDY

TOMS CANYON
SOUTH TOMS CANYON

BERKELEY CANYON

40°

CARTERET

CANYON
LINDEN KOHL

WILMINGTON
CANYON

BALTIMORE
CANYON

75c

74°

73°

72°

Figure 1. Location of study area on Continental Slope off New
Jersey. Depths are in meters.

GEOLOGIC BACKGROUND

The continental shelfbreak in this area lies at about 140 m
water depth. The transition between the Continental Slope and
Continental Rise is near 2150 m (Figure 2) . Between Lindenkohl
and Carteret Canyons the slope surface is relatively smooth, but
from Carteret Canyon to Toms Canyon, the slope surface is very
complex, cut by Berkeley, South Toms, and Middle Toms Canyons. A
number of canyons or valleys head on the Continental Slope, below
the shelf break, and some, like Berkeley Canyon, do not extend to
the Continental Rise. Relief on the rise is primarily in broad
swales, in contrast to the canyons on the slope, but those swales
do not necessarily link with features on the slope.

Profiles across the slope to the upper rise, show that
slightly seaward dipping, sub-shelf Tertiary strata are truncated
at the slope and covered by Pleistocene deposits (Figure 3) . An
area of exposed Eocene rocks on the lower slope represents the
deep-sea unconformity Au (Tucholke and Mountain, 1979) . Eocene
rocks, topped by the Au unconformity, dip under the onlapping,
later-Tertiary and Pleistocene sediments of the upper rise.

203

20 KM

Figure 2. Bathymetric map. Contour interval 50 m.

Seismic profiles parallel to the contours near the middle of
the slope show the topography of canyons, smaller valleys, and
ridges (Figure 4) , and demonstrate the sedimentary framework that
creates the pattern of outcrops on the geologic map (Figure 5) .
Downslope-trending, mainly depositional, fingerlike ridges of
Pleistocene sediments separate outcrops of Tertiary strata in the
channel axes of the canyons and valleys.

204

AMCOR
,602

TWO-WAY TRAVEL TIME
0.4 SEC

WATER DEPTH
600 m

1.2 SEC

1200 m

1800m

'■aV5J .

^:Ei—

■■■■■■: •' -i ■ ■/■i'. • • ■:" ? :': ■ -l"?>>> r^V;V>. " @>:

Figure 3. Single-channel seismic-reflection profile of the
Continental Slope near Berkeley Canyon showing stratigraphic
relations and well control. B shows where profile of Figure 4
crosses. Vertical exaggeration about 12:1.

OLDER HISTORY AND PROCESSES

Whereas the early Tertiary strata are generally planar,
having been deposited on a surface of low relief, deposition since
the late Miocene appears to have emphasized surficial
irregularities rather than to have smoothed them (Figure 4) . We

205

suggest that the ridges bordering the canyons may be levees,
probably created by large turbidity currents that spilled out of
the canyons. Note the thinning-away from the canyon axes of the
ridges along a valley northeast of Carteret Canyon, and at
Berkeley and South Toms Canyons (Figure 4) . In some places these
canyons show as much as several hundred meters relief. Large
turbidity currents were probably created by storms and waves that
eroded and suspended fine-grained, glacially derived sediments at
a shoreline near the shelf edge during low sea-level stands.
Profiles along the lower slope (Figure 6) show clearly the
depositional nature of the canyon-bordering ridges in that
Pleistocene sediment is deposited locally over a nearly planar
unconformity on Eocene strata.

1450m

Figure 4. Seismic profile along the continental slope showing
shallow structure beneath present topography. SW to left, NE to
right. The two canyons to the NE are Berkeley and South Toms.

Seismic profiles across deeper, steeper places in the canyon
axes show truncations of once continuous beds; erosional deepening
has also taken place. Areally, there were several periods of
canyon cutting. Profiles along the upper slope between
Lindenkohl and Carteret Canyons show a number of buried valleys
within Miocene strata. Several filled and partially reexcavated
canyons also are present in the Pleistocene sediments of the upper
slope along the northeast sides of present canyons.

On the lower slope, less erosional deepening of canyons
occurred. However, there are great differences in the history or
stage of development of individual canyons. For example, whereas
Berkeley Canyon shows little erosional incision, Carteret shows
more, and South Toms Canyon is deeply excavated (Figure 6) .

206

20 KM

Figure 5. Geological map. Contour interval 50 m.

Excavation of channels also took place in the deep water of
the uppermost rise, creating the relief on the Au unconformity
(Figure 7) . The topography on that unconformity is probably of
Oligocene or early Miocene age. Buried valleys there are similar
in size to channels of the larger present-day canyons where they
cross the rise. The buried valleys are not expressed in the
present-day bathymetric surface. One of the buried channels was
drilled by the Deep Sea Drilling Project (DSDP) hole 604, and
clasts of Eocene rocks in a matrix of Miocene-aged fill were

207

LINE 92

Figure 6. Seismic profile along lower slope.

LINE 170

Figure 7. Seismic profile along upper Continental Rise. PL =
Pleistocene, P = Pliocene, M = Miocene, E = Eocene.

recovered (C.W. Poag, pers. commun. , 1983), showing that Eocene
rocks have been exposed for a long time on the lower slope.

SURFICIAL EROSIONAL FEATURES

The present surface of the Continental Slope is covered
nearly everywhere by as much as several meters of fine-grained

208

sediment which has been dated to be as old as 30,000 ybp (Prior et
al., 1984). Consequently, it is inferred that erosion of this
part of the slope has generally been minimal in post-Pleistocene
time, although extensive erosion of Pleistocene strata suggest
that erosional activity was great during the late Pleistocene.
Sea-MARC sidescan-sonar images of the heads of the canyons show
traces of truncated late-Pleistocene strata (Figure 8) . In those
areas, erosion appears to have acted in small bites. Individually
identifiable slump or slide scars are present on the upper and
middle slope, but they are not as common as we had expected when
we began this mapping project. Submersible observations revealed
meter-sized slumped blocks from place to place in the canyon heads
(Slater et al., 1981). One probable slide scar several hundred
meters long on the side of a small valley on the upper slope at
about 900 m water depth is shown in Figure 9.

44-

-I Km

5111

0011

Qt>OI

0£0I

50€HVK)EPW

,:.,,.,: \ |

Figure 8. Sea-MARC sidescan-sonar image of truncations of
Pleistocene strata near head of Berkeley Canyon. The sidescan-
sonar images in this paper display darkness in areas of returned
echoes. Areas where echoes were not received, usually because
they lie in an acoustic shadow, are white. In this image, the
sidescan fish was towed horizontally across the photograph at the
level of the zero on the distance scale. Sound was projected in
an upslope direction, toward the upper part of the image, and the
downhill-facing scarplets caused by differential erosion of the
Pleistocene strata reflected the acoustic signal more strongly
than their surroundings.

209

100

if 200

^300

I Km

Figure 9. Sidescan-sonar image of small slide on upper
Continental Slope in Pleistocene deposits. Water depth about 900
m. Fish location for this image is similar to Figure 8. Upslope
is to the upper left. The wall of a small valley that runs from
upper left to lower right is cut by a slide scar.

210

There is evidence for episodic mass transport. Linear mounds
of sediment overlie Pleistocene sediments along the present slope-
rise boundary. Piston cores show Eocene clasts in Pleistocene
matrix, suggesting that the mounds are debris-flow deposits from
the lower slope. Profiles show similar structure in strata as
old as Miocene. Sea-MARC images show a debris deposit on the
upper rise at the mouth of South Toms canyon (Figure 10) , and
observations of the area from Alvin show clasts of Eocene rocks
like those that crop out on the lower slope. This material
probably originated in a rockfall within the canyon and was
transported to the rise by debris flow. We observed places in
other canyons or valleys of the lower slope where cliffs showed
fissures along their rimrocks that portend future rockfalls. Our
sidescan-sonar coverage of South Toms Canyon is incomplete, and we
do not know the site from which this particular material came or
when the event occurred.

SOUTH TOMS CANYON
SLOPE /RISE BOUNDARY \

Figure 10. Sidescan-sonar image of debris on upper Continental
Rise near mouth of South Toms Canyon. There are marked
differences in this area in the acoustic backscattering qualities
of the slope and rise that create distinct tonal changes at the
slope/rise boundary. Much of the roughness on the rise shown here
is caused by meter-sized blocks of Eocene rocks deposited by a
debris flow or rockslide.

Steep-walled basins (Figure 11) are found in a number of
valleys that cut the lower slope and in the lower reaches of
Carteret Canyon. Some resemble slump scars; others are terraced

211

Figure 11. Valley basin on lower Continental Slope. Water depth
about 2000 m. Sidescan fish was towed across the middle of this
image. Upslope to upper right. Note shape of valley, and
terraces at bedding surfaces. Smaller basin at left.

and appear to have been eroded along bedding planes in
consolidated chalks and mudstones. The basins are found along the

212

slope, from valley to valley, in places that appear to correspond
to certain stratigraphic intervals. Observations from Alvin in
two of the basins show that their cliffed walls are undercut in
many places, and that cliff and valley orientation is controlled
by joints. In two locations sandstone dikes were observed,
projecting from valley walls or floors (Figure 12) . Arched
recesses were also observed in cliff faces. Several recesses
expose 8- to 10-cm diameter tubes that we believe to be fossil
burrows of Miocene cerianthid anemones (Figure 13) .

Figure 12. Sandstone dike in a cliff-walled valley observed from
Alvin. Image spans about 5 m. Water depth about 1500 m.
Fragile, easily broken dike and abrupt, clean projection from
cliff on both sides implies lack of landslide and some other
process than current erosion for wall retreat.

It has been suggested (Robb et al., 1982b; Robb, 1984) that
these steep-walled valley basins may have been created by what
Douglas Johnson (1939) , in an early paper on the origin of
submarine canyons, called artesian spring sapping. Excess pore
pressure could result from the differential head between now-
subaerial parts of the Coastal Plain and the sediment below the
Continental Shelf and Slope during periods of low sea level. The
concept is supported by digital hydrologic modelling, using modern

213

Figure 13. Alcove in valley wall observed from Alvin.
Cylindrical features (about 10 cm in diameter) are believed to be
fossilized tubes of Miocene cerianthid anemones. Tubes are
fragile. Erosion has been slow, localized, and not by landslide.
Water depth about 1500 m. Similar appearing alcoves in Colorado
Plateau area are attributed to groundwater sapping along bedding
planes.

seismic-reflection profiles and permeability data from the
Continental Offshore Stratigraphic Test (COST) well B-2 on the
Continental Shelf (Leahy and Meisler, 1982) .

Steep-headed basins having undercut walls are characteristic
of spring-sapped features (Higgins, 1982) . The sandstone dikes
observed from Alvin are fragile, and protrude from the cliff face
by as much as one meter (Figure 12) . One such dike was easily
sampled using Alvin1 s manipulator. Its preservation implies slow
erosion of that cliff face, consistent with erosion by groundwater
discharge, but inconsistent with mass movement. Similarly, the
arched recesses with exposed, fragile trace fossil simply slow,
particle by particle erosion (Figure 13) . Arched recesses in
canyons in the southwestern United States are attributed to
groundwater seepage (Robinson, 1970) .

Another process that may have acted on the lower slope is
solution of calcareous rocks and cements. Should fresh

214

groundwater be discharged into seawater, a mixture is created that
is more corrosive than either of the components. Bays on the
coast of Yucatan, for example, are attributed to rapid erosion by
discharging groundwater mixing with seawater (Hanshaw and Back,
1980) . Reticulate linear depressions in the lower slope resemble
fissures along joints that are a common karst phenomenon (Figure
14) . Although specific reticulate linear depressions were not
directly observed from a submersible, we did observe gaping
fissures along joints elsewhere in cliff faces.

T1"

•a* •.'

'5b.

I^te^jfr — ■-. ,...;,■,. ■-..■. '.^.V.)

Wfcl

Figure 14. Sidescan-sonar image of reticulate sea-floor fissures
located near Berkeley Canyon. Water depth about 17 00 m.
Probably Miocene terrain. Arrows at the top of this image show
the direction of sidescan view. Here, the sidescan fish was towed
along the top of the photograph, and linear fissures appear as
white shadowed areas.

There are features of the faces of outcrops that may also be
products of solution. Figure 15 shows some small depressions that
look like solution pits along the near-horizontal outcrop of a
bedding plane. We speculate that the vertical grooves above those
pits may be analogous to rill lapies, or rillenkarren, karst
features thought to be formed by rainwater running down an
outcrop. If freshwater were expelled along a bedding plane,
would it rise through the denser seawater and create an "upside-
down" lapies pattern?

215

Figure 15. Outcrop observed from Alvin in lower slope valley.
Note solution pits (?) along bedding plane, and rilled surface.
See text. Image spans about 3 m. Water depth about 2000 m.

SUMMARY

On the Continental Slope, deposition and erosion have
operated at different rates in different times and in different
places on the slope. Much of the present surface is old. The
upper slope topography, including the canyons, is cut in late
Pleistocene deposits. Intercanyon ridges on the middle slope are
of Pleistocene age, and result primarily from deposition on a pre-
Pleistocene erosional surface, although some of the larger ridges
were initiated during the late Miocene. The lower slope features,
of smaller dimensions, are primarily erosional, and were created
by many processes over a long time. Overall, the present
geomorphic picture is of deposition sculpted by erosion, and
finally covered by thin recent sediment. Because there is
evidence of geologically recent slides or rockfalls whose historic
age is not known, in a terrain having steep slopes and cliffed
outcrops, common prudence would dictate caution and pre-placement
investigation for any engineering effort.

216

ACKNOWLE DGEMENTS

Investigations reported in this paper were funded by the U.S.
Bureau of Land Management under Memoranda of Understanding
AS551MU821, AA551MU94, AA851MU018, and Interagency Agreements
AA851IA117, and AA851IA226, between the BLM and the U.S.
Geological Survey.

LITERATURE CITED

Grow, J. A., R.E. Mattick, and J.S. Schlee. 1979. Multichannel
seismic depth sections and interval velocities over outer
Continental Shelf and upper Continental Slope between Cape
Hatteras and Cape Cod. American Association of Petroleum
Geologists Memoir 28: 65-83.

Hampson, J.C, Jr., and J.M. Robb. 1984. Geologic map of the
Continental Slope between Lindenkohl and South Toms Canyons,
offshore New Jersey. U.S. Geological Survey
Miscellaneous Investigation, 1-1608, scale 1:50,000.

Hanshaw, B.B., and W. Back. 1980. Chemical mass-wasting of the
northern Yucatan Peninsula by groundwater dissolution.
Geology 8: 222-224.

Higgins, C.G. 1982. Drainage systems developed by sapping on
Earth and Mars. Geology 10: 147-152.

Johnson, D. 1939. The origin of submarine canyons, a critical
review of hypotheses. Columbia University Press, New York,
126 p.

Kirby, J.R., J.M. Robb, and J.C. Hampson Jr. 1982. Detailed
bathymetry of the United States Continental Slope between
Lindenkohl and South Toms Canyons, offshore New Jersey.
U.S. Geological Survey Miscellaneous Field Investigations,
MF-1443, scale 1:50,000, 1 sheet.

Leahy, P., and H. Meisler. 1982. An analysis of fresh and
saline groundwater in the New Jersey Coastal Plain and
Continental Shelf (abs) . EOS, Transactions American
Geophysical Union 63: 322.

Poag, C.W. , pers. comm. , 1983. U.S. Geological Survey, Woods Hole,
MA 02543.

Prior, D.B., J.M. Coleman, and E.H. Doyle. 1984. Antiquity of
the continental slope along the Middle Atlantic margin of
the United States. Science 223: 926-928.

Robb, J.M. , J.C. Hampson Jr., J.R. Kirby, and D.C. Twichell.
1981a. Geology and potential hazards of the Continental
Slope between Lindenkohl and South Toms Canyons offshore
Mid-Atlantic United States. U.S. Geological Survey Open-
file Report 81-600, 21 p., 22 figs., 3 maps.

Robb, J.M., J.C. Hampson Jr., and D.C. Twichell. 1981b.
Geomorphology and sediment stability of a segment of the
U.S. Continental Slope off New Jersey. Science 211: 935-
937.

Robb, J.M., J.C. Hampson Jr., and J.R. Kirby. 1982a. Surficial
geologic studies of the Continental Slope in the northern
Baltimore Canyon trough area — techniques and findings.
1982 Offshore Technology Conference Proceedings 1: 39-59.

217

Robb, J.M., D.W. O'Leary, J.S. Booth, and F.A. Kohout. 1982b.
Submarine spring sapping as a geomorphic agent on the east
coast continental slope (abs) . Geological Society of
America, Abstracts with Programs 14(7) :600.

Robb, J.M., J.C. Hampson Jr., J.R. Kirby, P.C. Gibson, and B.
Hecker. 1983. Furrowed outcrops of Eocene chalk on the lower
Continental Slope offshore New Jersey. Geology 11: 182-
186.

Robb, J.M. 1984. Spring sapping on the lower continental slope,
offshore New Jersey. Geology 12: 278-282.

Robinson, E.S. 1970. Mechanical disintegration of the Navajo
sandstone in Zion Canyon, Utah. Geological Society of
America Bulletin 8: 2799-2806.

Slater, R.A. , D.C. Twichell, and J.M. Robb. 1981. Submersible
observations of possible geologic hazards along the Mid-
Atlantic Continental Shelf and upper Slope. U.S. Geological
Survey Open-File Report 81-968, 57 p., 22 figs.

Tucholke, B.E., and G.S. Mountain. 1979. Seismic stratigraphy,
lithostratigraphy, and paleosedimentation patterns in the
North American basin. In: M. Talwani, W. Hay, and W.B.F.
Ryan (eds) , Maurice Ewing Series 3: Deep Drilling Results in
Atlantic Ocean; Continental Margins and Paleoenvironment,
pp. 58-8 6. American Geophysical Union, Washington, D.C.

NOAA Symp. Ser. for Undersea Res. 2(2), 1987 219

SEDIMENT TEXTURE AND DYNAMICS OF OUTER SHELF AND
UPPER SLOPE DEPTHS ON THE SOUTHERN FLANK OF GEORGES BANK

Page C. Valentine
U.S. Geological Survey
Woods Hole, MA 02543

ABSTRACT

Observations from submersible dives on the outer shelf, in
the head of Oceanographer Canyon, and on the nearby gullied upper
slope indicate that sediment dynamics differ markedly in adjacent
areas at the same water depth (150-650 m) on the southern
flank of Georges Bank. Sediment types in Oceanographer Canyon
are immobile gravel on the rim, firm bioeroded silt exposed on the
lower walls, and rippled and duned medium to coarse sand on the
walls and floor. Upper slope sediment is unrippled, finer grained
sand. Shelf currents transport sand onto both the canyon wall and
upper slope; contrasts in the texture of the mobile sediment in
the two areas are directly related to the strength and orientation
of bottom currents. Current observations are based on results of
long-term deployments of current meters by other workers, and on
in situ observations from submersibles. Along-shelf currents of
unknown origin flow westward across the canyon rim. Strong north-
south tidal currents dominate flow up and down the canyon axis to
at least 630 m, and their strength is related to canyon size and
shape. In contrast, tidal currents on the upper slope are weak,
but strong currents related to Gulf Stream eddies flow eastward
along the slope above 300 m. Major sea floor processes in the
energetic canyon head are erosion and transport out of the canyon
of fine-grained sediment accompanied by accumulation of shelf sand
on the canyon floor; whereas deposition of fine sediment as well
as sand is more likely to occur in the same depth interval on the
more tranquil upper slope.

INTRODUCTION

Recent investigations of the geology and biology on the
southern flank of Georges Bank in the vicinity of Oceanographer
and Lydonia Canyons have focused on sediment texture and
transport, the distribution of sediment types, and the description
of the faunal assemblages and habitats (Valentine et al., 1980,
1984a, b; Twichell, 1983; Cooper et al . , in press). During the same
period, hydrodynamic studies have identified the major current
patterns in the region (Keller and Shepard, 1978; Butman et al.,
1982, 1983, in press; Butman and Beardsley, in press). In
particular, the Lydonia Canyon hydrodynamic experiment done by
Butman and his colleagues has contributed greatly to the
explanation of sediment transport patterns that previously had
been inferred from textural analyses, from sedimentary features,
and from a few observations of current speed and direction made
from submersibles.

The outer shelf and upper slope is a transitional sedimentary
province characterized by an increase in the steepness of the sea

220

floor. The study areas (Figure 1) exhibit a wide variation in
sedimentary environments that are related to sea floor morphology,
to sediment sources and to current patterns. In water depths
between 150 and 650 m, a relatively smooth, seaward-facing outer
shelf and upper slope, oriented approximately east-west, is
incised at about 350 m by narrow, steep-walled gullies that extend
far downslope (Figures 2 and 3b) . By contrast, in the same depth
interval, the shelf edge is incised by canyons of varying size
that are oriented approximately north-south.

Georges Bank is isolated from continental sediment sources by
the Gulf of Maine. On the southern flank of the bank, bottom
sediment varies in texture from cobble and boulder gravel pavement
on the canyon rims to silty sand on the upper slope. Excluding
the presently immobile cobbles and boulders and the extensive
deposits of bioeroded, semiconsolidated Pleistocene silt exposed

40°I0-

Figure 1. Location of study areas on southern flank of Georges
Bank. Most samples from outer shelf-upper slope are from area to
east of Oceanographer Canyon (Figure 3B) ; 5 samples from shelf-
slope transition to west of Heel Tapper Canyon are included in
textural analyses (Figures 6 and 7) .

221

on the lower canyon walls, the principal source of sediment for
both the canyons and the upper slope is relict Pleistocene sand on
the shelf.

mm DUNES ON CANYON FLOOR
EH GRAVEL PAVEMENT

EXPLANATION

EE3 GULF STREAM EDDY ON BOTTOM

Figure 2 . Current patterns and sediment dynamics on the southern
flank of Georges Bank. Study areas in Oceanographer Canyon and
outer shelf-upper slope to east outlined (Figure 3). Width of
arrows represent relative current strength. Two-headed arrows
represent major axis of semidiurnal tidal ellipse; arrows in
Lydonia Canyon area represent stations of Butman et al. (1983).
Tidal currents are strong on shelf and on canyon floors, most
energetic in Oceanographer Canyon and diminished on upper slope.
West-facing arrows represent strong current on east rim of
canyons. East-facing dashed arrows schematically represent strong
current associated with Gulf Stream eddies. Mean current is to
southwest in this region with a weak off -shelf component near the
sea floor (not shown) .

Although the region is hydrodynamically complex, recent
studies have made it possible to identify several factors that
have a major influence on sedimentary processes (Butman et al.,
1982, 1983, in press). The seasonal mean circulation flows
clockwise around Georges Bank, and its cause has been attributed

222

to several forcing mechanisms including surface wind-
stress, horizontal density gradients such as the shelf water-
slope water front, rectification of tidal currents, and regional
pressure gradients. On the southern flank of Georges Bank mean
flow generally is to the southeast at about 5 to 10 cm/s.
However, there is an off -bank component flowing at about 3 to 8
cm/s near the sea floor in the Lydonia Canyon region (Butman et
al., 1983, Figure 8-18). The mean current is too weak to move
shelf and upper slope sediment as bed load, but it is strong
enough to transport silt and clay particles off the bank once they
are suspended by more vigorous currents produced by storms, tides,
and Gulf Stream eddies.

Strong semidiurnal tidal currents are oriented approximately
north-south, parallel to the canyons but normal to the trend of
the seaward-facing upper slope. Preliminary results of the
Lydonia Canyon experiment show that the strongest flow along the
canyon floor reverses direction each day at the semidiurnal tidal
period (Butman et al., 1983, Figures 8-25c, d, 8-26c) . At
present, it is unclear whether this motion is a semidiurnal
barotropic tide (M2) or an internal tide, and an analysis of its
internal structure is required to answer this question. In this
paper, the reversing flow within the canyons is referred to as the
semidiurnal tide. In addition to the tidal currents within the
canyons, a strong current of uncertain origin flows westward
across the canyon rims. Gulf Stream eddies occasionally impinge
on the southern flank of the bank; circulation within the eddies
is clockwise and produces strong bottom currents that flow
eastward along the upper slope.

The purpose of this paper is to describe sediment textures
that lie within the same depth interval in Oceanographer Canyon
and on the adjacent outer shelf and upper slope (Figure 1) and to
relate sediment dynamics in the two areas, and on the southern
flank of Georges Band in general, to sea floor morphology and to
prevailing current systems. Observations and sampling of the sea
floor were carried out by submersible and supplemented by grab
sampling and bathymetric surveys from a surface ship (Figure 3) .
In a study of this nature, the use of a submersible is necessary
for sampling areas such as steep walls, narrow canyon and gully
floors, and localized sedimentary environments that are
inaccessible to grab samplers or difficult to locate from a
surface ship.

SEDIMENT TRANSPORT AND CURRENTS

Oceanographer Canyon

Oceanographer Canyon, the largest of the Georges Bank
canyons, incises the shelf some 22 km and exhibits many different
bottom types. The surficial geology of the northern part of this
canyon has been treated elsewhere and only a brief description is
presented here (Valentine et al., 1980, 1984a, b) . Coarse to fine
rippled shelf sand is present around the canyon to about 150 m
where it gives way to gravel and gravelly sand on the rim (Figure
4) . The upper walls are generally covered by a thin veneer of
rippled silty sand; the silt is incorporated into the sand from

223

OUTER SHELF /UPPER SLOPE

Figure 3. A) Oceanographer Canyon, northern part, showing dive
tracks and locations of sediment samples; dot pattern
represents canyon floor where strong tidal currents flow and where
rippled sand and dunes are present. B) Outer shelf -upper slope
east of Oceanographer Canyon showing dive tracks and locations of
sediment samples. Textures of samples from canyon floor and from
outer shelf-upper slope presented in Figures 6 and 7.

below by burrowing infaunal organisms, chiefly annelid worms. The
lower canyon walls exhibit broad exposures of semiconsolidated
silt of Pleistocene age that is often burrowed by crustaceans.
The canyon floor is covered by dunes of coarse to medium rippled
sand.

Bed forms and sediment textures indicate that bottom currents
are very energetic within the canyon and on the shelf around it
(Figure 2) . The canyon is oriented approximately north-south,
parallel to the strong semidiurnal tide which is the strongest
current flowing along the axis here and in adjacent Lydonia Canyon
(Butman et al., 1983). Ripples in sand on the canyon walls are
generally aligned normal to the tidal flow as are large
asymmetrical dunes on the canyon floor that range up to 3 m in

224

height. The size of the bed forms and the fact that the sand on
the canyon floor is almost free of silt and clay (even though
bioerosion of the Pleistocene silt on the lower walls is
extensive) are evidence that tidal flow is very strong along the
axis. During several dives in Oceanographer Canyon, currents on
the canyon floor have been observed to flow at speeds of 50 to 100
cm/s, and Butman et al. (1983) recorded maximum speeds of 73 cm/s
and 96 cm/s at two current meter stations in the axis at 227 m and
560 m, respectively.

Another major flow pattern is present on the eastern canyon
rim where a large area of cobble and boulder pavement is present
between 150 and 275 m. Dives up the east wall encountered a
strong current of at least 50 cm/s flowing westward across the
gravel. This current transports shelf sand onto the canyon wall.

Figure 4. Oceanographer Canyon; schematic oblique view of east
(right) and west (left) walls looking north, upcanyon; no scale.
West wall: rippled shelf sand and gravelly sand transported down
wall (small arrows) by tidal currents aided by gravity; annelid
burrows into underlying silt (elongate symbols) ; sand probably
overlies gravel deposits similar to those exposed on east wall;
Pleistocene silt exposed on lower wall and burrowed by crustaceans
(oval symbols) ; solid triangles at base of wall represent eroded
silt fragments; large, asymmetrical, rippled sand dunes migrate
up- and downcanyon floor in response to strong tidal flow (two-
headed arrows) and fine sediment winnowed. East wall: strong
westward current (one-headed arrow) transports shelf sand onto
wall and exposes ice-rafted glacial deposits.

225

The gravel layer is interpreted to be ice-rafted debris deposited
during the late Pleistocene. It is probably also present on the
western rim, but there it is partly buried by shelf sand to form
gravelly sand. The westward flow across the eastern rim is strong
enough to winnow and transport sand through the gravel downslope
into the canyon, but is ineffective in transporting sand up-slope
onto the shelf to expose the gravel on the western rim. The
current may be discontinuous, or in its passage across the canyon
its speed may be reduced, or at full strength it simply may not be
capable of moving sand back onto the shelf.

A similar current has been observed on the east rim of
Lydonia Canyon (Butman et al., 1983). The current is oscillatory,
and major flow directions are east and west. However, the current
is unusual because eastward flow is much weaker than westward flow
which reaches hour-averaged speeds of 50 cm/s or more, similar to
speeds observed from submersibles on the east rim of Oceanographer
Canyon. The origin and extent of this distinctive current is not
known, although the sparse data available suggest that it may be a
local phenomenon in part related to tidal effects and to changes
in bottom morphology and water depth at the canyon edge (B.
Butman, personal commun., 1984).

Textural analyses, bedform orientation, and current patterns
suggest that storm currents and strong semidiurnal tidal currents
transport sand off the shelf onto the canyon walls. Tidal
currents move it up- and downcanyon along the wall and eventually
onto the canyon floor; subsequently, the sand is transported up-
and downcanyon along the floor, formed into ripples and dunes, and
the fine sediment derived from bioerosion of the canyon walls is
removed. Superimposed on this north-south transport pattern is
the strong current that flows westward across the east rim and
transports shelf sand onto the canyon wall.

Outer Shelf and Upper Slope

The principal outer shelf-upper slope area under study is
located about 9 km east of the mouth of Oceanographer Canyon
(Figures 1, 3B) . In addition, a suite of 5 samples from a similar
setting to the west of Oceanographer Canyon is included in the
study (Figure 1) . The sea floor from the outer shelf down to
about 650 m on the upper slope is a relatively homogeneous sheet
of sand that becomes increasingly silty with depth (Figures 5 and
6) . Sand present from 175 m to about 300 m contains 5% or less
silt and clay and is typical of shelf sand around the canyons, but
silt and clay increase in weight to about 3 6% at 64 0 m on the
gullied upper slope. Scattered patches of gravel are present in
the shelf-slope transitional area, suggesting that ice-rafted
gravel deposits are present but have been buried to a large extent
by the layer of sand. The gullies that "head" at about 350 m have
walls that are inclined at 35° to 40°. However, the underlying
Pleistocene silt that is so extensively exposed in Oceanographer
Canyon is rarely observed. Ripples are rare at outer shelf depths
greater than about 190 m, and the gully floors are covered by a
smooth layer of silty sand. Gravity slides initiated by contact
of the submersible with the gully walls suggest that the silty
sand is at or near its angle of repose.

226

These observations indicate that the outer shelf -upper slope
region experiences weaker currents than does the nearby canyon
within the same depth interval (Figure 5) . The upper slope is
oriented normal to the semidiurnal tide, and Butman et al. (1983,
Figures 8-24a, 8-24b) have shown that semidiurnal tidal currents
become weaker with depth at two stations located at 250 m and 571
m on the slope east of Lydonia Canyon, about 3 5 km east of the
present study area (Figure 2) . The most vigorous currents on the
upper slope are associated with Gulf Stream eddies and flow
eastward at hour-averaged speeds up to 4 5 cm/s at about 2 50 m
(Butman et al., 1983). It is apparent that storm currents
transport shelf sand onto the upper slope where it becomes mixed
with an increasing amount of silt and clay through the activities

170m

SHELF

*??+&*

2 — S — S t — » — «.»» * * » »* # »

SEM/COA/s.

SHELF

600 m

200 -600 m

WEST

Figure 5. Oceanographer Canyon and adjacent outer shelf-upper
slopes; schematic oblique view of canyon west wall looking north,
upcanyon, and of outer shelf-upper slope looking east, along
slope; no scale. West wall: (as in Figure 4). Outer shelf-upper
slope: rippled shelf sand transported to outer shelf (solid
arrows) chiefly by storm currents; annelid burrows into
underlying silt (elongate symbols) ; along-slope transport to east
above 250-300 m by Gulf Stream eddy currents (dashed arrow) ;
bedforms rare or absent ort upper slope, and not observed on gully
floors; crustacean burrows in Pleistocene silt rare (oval
symbol) ; silty sand on steep gully walls at angle of repose.

227

OCEANOGRAPHER CANYON
o Canyon floor (36)

OUTER SHELE-UPPER SLOPE
• East of canyon (24)

® •

U
2

ir
<

0
0

°* • o

0
G G

G* "
G

G G

• •

G ©

G °

G o

100

200

300 400 500

WATER DEPTH, METERS

600

700

Figure 6. Mean grain size (phi) versus depth for sediment samples
from the floor of Oceanographer Canyon and from the adjacent outer
shelf-upper slope. Note that upper slope samples are finer
grained than canyon samples in water depths greater than about 3 00
m. Sediment from floor of slope gullies is no coarser than other
slope sediment at equivalent depths.

of small organisms that burrow into the underlying silt and
through deposition from suspension. Bioerosion of Pleistocene silt
by crustaceans is minor because the relatively weak currents on
the slope cannot remove the veneer of sand from even the steep
gully walls.

Sediment Texture and Current Strength

Keeping in mind that the shelf is the source of sand for both
the canyon and the slope, a comparison of the mean grain size of
sediment collected from the floor of Oceanographer Canyon and from
the same depth interval on the outer shelf-upper slope region

228

illustrates the differences in the strength of bottom currents in
the two sedimentary provinces (Figure 6) . Medium to coarse sand
is present from 135 m in the canyon head down to 630 m on the
canyon floor, whereas the outer shelf -upper slope is covered by
fine to medium sand from 175 m to about 300 m. Between 300 m and
640 m, the upper slope sediment becomes increasingly finer-grained
with coarse silt dominating below 600 m.

Another measure of relative current strength is the weight
percent of silt and clay in samples from the canyon and upper
slope (Figure 7) . On Georges Bank, shelf sand is constantly
reworked by tidal and storm currents and commonly contains 5% or
less silt and clay. The coarse sediment on the floor of
Oceanographer Canyon typically exhibits similar values of silt and
clay content that result from the winnowing by tidal flows of
fine-grained sediment eroded from the silt exposed on lower canyon

_i
o

Q
<

OCEANOGRAPHER CANYON
O Canyon floor (36)

OUTER SHELF -UPPER SLOPE
• East of canyon (24)

• •

®*

CD
LlI

• •

300 400 500

WATER DEPTH, METERS

600

Figure 7. Silt and clay weight percent versus depth for sediment
samples from the floor of Oceanographer Canyon and from the
adjacent outer shelf-upper slope. Silt and clay content of
Georges Bank shelf samples at depths to 200 m typically 5% or
less. Note increase of silt and clay in upper slope sediment
below 300 m. Sediment from floor of slope gullies also contains
large percentages of silt and clay.

229

walls. By contrast, samples from the outer shelf -upper slope
transition contain an increasing amount of silt and clay with
depth below about 300 m. Even sediment collected from the floors
of the gullies on the upper slope does not depart from this trend.
The low percentages of silt and clay above 300 m may result from
the winnowing activity of the relatively strong currents
associated with Gulf Stream eddies (Figure 2) . The eddies
observed during the Lydonia Canyon experiment were shallow
phenomena, and the strong currents at their base did not affect
the slope below about 250 m (Butman et al., 1983). The increase
in fine sediment on the upper slope below 3 00 m can be attributed
to a general weakening of tidal and storm currents with
depth.

INFLUENCE OF CANYON SIZE AND SHAPE ON CURRENTS

The sedimentary deposits on the floor of Oceanographer Canyon
and the upper slope are very different texturally, yet the bulk of
the sediment found in both areas is derived from shelf sand, and
the two sedimentary provinces are located adjacent to one another
in the same depth interval (150-650 m) . Both areas experience the
north-south semidiurnal tide, and maximum tidal currents along the
floor of the canyon reach speeds of 50 to 100 cm/s. In
comparison, on the upper slope near Lydonia Canyon all 5 principal
semidiurnal and diurnal tides combine to produce maximum currents
of only about 12 cm/s at 245 m (5 meters above bottom) and 5 cm/s
at 471 m (100 mab) (Moody et al., 1984). The strongest currents
on the slope are associated with Gulf Stream eddies and reach
maximum hour-averaged speeds of about 4 5 cm/s directed along
slope. Tidal forces are aligned parallel to the axis of
Oceanographer Canyon, suggesting that its size and shape may
constrain flow direction and enhance flow speed.

The canyons on the southwestern flank of Georges Bank vary
greatly in size. Although they share the same physiographic
setting, the differences in bedforms, sediment texture, and
maximum current speeds observed so far indicate that current
energy levels also differ in these canyons. Sand dunes of medium
to coarse sand up to 3 m in height are present on the floor of
Oceanographer Canyon, the largest of 12 canyons that incise the
shelf in this region. Dunes also have been reported from the
floor of Hydrographer Canyon, the second largest canyon (Southard
and Stanley, 1976, p. 368; Keller and Shepard, 1978, p. 30). The
floor of Lydonia Canyon, the fourth largest canyon, is covered by
fine to medium rippled sand (Twichell, 1983; Butman, et al., 1983)
and for the most part it is finer grained than that found in
Oceanographer Canyon. However, a dive along the axis of Lydonia
Canyon traversed an area of rippled sand and low dunes at a depth
of about 600 m (B. Butman, personal commun. , 1984). Sediment
collected from this area is the coarsest found on the canyon floor
and contains only about 10% silt and clay (Butman et al., 1983,
Figures 8-lla, b, c) . The floors of other canyons have not
been surveyed or sampled thoroughly. Bottom photographs obtained
on dives by scientists of the U.S. Geological Survey and the
National Marine Fisheries Service reveal the presence of fine-
grained sediment and ripple marks on the floor of Veatch Canyon,

230

the fifth largest canyon. Atlantis Canyon, the second smallest of
the 12 canyons considered here, exhibits a locally rippled floor
of fine-grained sediment.

If sediment dynamics differ in canyons that share a common
sediment source and a similar hydrodynamic setting, there should
be a correlation between canyon size or shape and the speed of the
dominant current, the semidiurnal tidal flow. It is not yet
known whether the strong bottom currents in the canyon are caused
by the semidiurnal barotropic tide (M2) or by a semidiurnal
internal tide that is set up by the interaction of the M2 tide
with the canyon walls and floor. Hotchkiss and Wunsch (1982)
studied internal tides in Hudson Canyon and the effect of canyon
shape on current strength. They concluded that the strength of
the internal tide depends in a complex way on the strength of the
surface tide, canyon length, cross-sectional area,
and the slope of canyon walls and floor.

The present study does not have the hydrodynamic data to
determine quantitatively the effect of canyon shape on current
strength. However, it is possible to make a qualitative
determination by comparing the sedimentary environments observed
in the Georges Bank canyons with canyon morphology. The volume,
axial length, mouth height and mouth width were calculated from
the 12 canyons that incise Georges Bank shelf from Powell Canyon
in the east to Alvin Canyon in the west (Figure 8) . These
measurements were arbitrarily limited to the region between the
canyon head and the shelf edge at the 200 m isobath, because the
most active currents are found there [based on sediment texture
and bedform analysis and on current speeds measured by Butman et
al. (1983)].

The largest canyon considered here (Oceanographer) is more
than 50 times larger than the smallest (Shallop) , and there is a
strong positive correlation between axis length and canyon volume
(r = 0.88) and between mouth height and canyon volume (r = 0.92).
However, the width of the canyon mouths does not vary in a
systematic way with volume (r = 0.10). Oceanographer and
Hydrographer Canyon are larger, longer, and deeper than the
others, and based on the evidence presented above, they are the
most energetic of all the canyons. It is difficult to ascertain
whether the "energy level" of a canyon depends on its volume or is
related to a combination of volume, axial length, and mouth
height. Gilbert and Lydonia are the third and fourth largest
canyons, respectively. Gilbert has the higher mouth of the two,
but Lydonia is longer. Further study of Gilbert and some other
canyons is needed to resolve this issue. At present, canyon
volume is inferred to be an important factor, and based on volume
alone, the 12 canyons are categorized preliminarily into groups
representing high, moderate, and low energy levels.

Oceanographer and Lydonia Canyons are the best known canyons
with regard to sediment textures, bedforms, and bottom currents.
Oceanographer is almost five times larger than Lydonia, and this
difference in volume apparently affects the strength of currents
on the canyon floors. Bottom currents in Oceanographer and
Lydonia reach maximum speeds of about 100 cm/s and 50 to 60 cm/s,
respectively, and produce quite different sedimentary environments
in canyons that are located only 4 0 km apart. Heel Tapper Canyon

231

401-

GEORGES BANK CANYONS
ENERGY LEVEL

Low

a r

Moderate

A / \

High

MOUTH WIDTH %/*

•

| CANYON
VOLUME

| AXIS
LENGTH

4 MOUTH
HEIGHT

SHI All DB HI Ail/ PWL WEL VCH LYD GIL

HYD OCG

1.0

Figure 8. Dimensions and energy levels of 12 Georges Bank
canyons. Dimension measured from bathymetry by Carpenter et al.
(1982) . Canyons arranged left to right in order of increasing
volume. Canyon names: SHL, Shallop, ATL, Atlantis; DB, Dogbody;
HT, Heel Tapper; ALV Alvin; PWL, Powell; WEL, Welker; VCH, Veatch;
LYD, Lydonia; GIL, Gilbert; HYD, Hydrographer, OCG,
Oceanographer .

is a small canyon that lies adjacent to Oceanographer Canyon and
shares the same environmental setting (Figures 1 and 8) . This
canyon has not been visited with a submersible or sampled, but
based on size alone, one would infer from the foregoing discussion
that its energy level is low, perhaps more similar to that of the
upper slope than to that of its large energetic neighbor.

SUMMARY

The major geologic and hydrodynamic factors that shape the
sedimentary environments present in the Georges Bank canyons and
on the intervening upper slope include the current regime, the
sediment source, and the physiographic setting of the southern
flank of the bank (Fig. 2) . The bottom-current systems most
important in eroding and transporting sediment in this region are:
a. storm currents on the shelf; b. north-south semidiurnal tidal
currents on the shelf and in the canyons; c. the westward-flowing

232

current on the east rims of the canyons; and d. the eastward-
flowing current on the outer shelf and upper slope that is part of
the circulation of Gulf Stream eddies. The chief sediment source
for the canyons and upper slope is shelf sand; a secondary source
is the Pleistocene silt that is exposed on the lower canyon walls
and covered by a thin layer of sand on the upper slope. The upper
slope is oriented east-west whereas the canyons are aligned north-
south, and canyon shape and size has an important influence on the
strength of tidal currents flowing along the canyon floors.

A comparison between canyon and outer shelf -upper slope
sedimentary environments areas follows:

Canyon
(135-630 m)

Outer Shelf-Upper Slope
(175-640 m)

Semidiurnal tidal
currents flow
parallel to canyon
axis; canyon size and
shape intensify tidal
flow speeds, and the
largest canyons are
most energetic-
speeds reach 100 cm/s
in Oceanographer
Canyon.

Semidiurnal tidal
currents flow normal
to the trend of the
slope; flow speed is
weak and diminishes
with depth and, based
on sediment texture,
is not intensified in
slope gullies.

Westward flow of 50
cm/s of unknown
origin exposes gravel
on east rims of
Oceanographer and
Lydonia Canyons and
transports shelf sand
onto east wall.

No equivalent
westward flow.

Gulf Stream eddy
circulation is not
present below about
250 m and is not a
major factor
influencing bottom
flow in canyon.

Eastward currents
with speeds up to 45
cm/s are associated
with warm Gulf Stream
eddies and affect
outer shelf and upper
slope sediment to
about 2 50 m.

Oceanographer
Canyon: shelf sand
is transported onto
canyon walls by
storms and tidal
currents and onto
east wall by westward
along-shelf current;
tidal currents move
sand along and down

Shelf sand is trans-
ported onto gullied
upper slope princi-
pally by storm cur-
rents; along-slope
transport to east is
by Gulf Stream eddy
currents; ripples are
rare below about 190
m; no bedforms on

233

walls onto floor and
then up and down
canyon along floor
winnowing fine
sediment; floor is
covered by rippled
sand dunes.

Lydonia Canyon;
similar to
Oceanographer, but
axial currents are
weaker and canyon
floor sediment
contains more silt
and clay; rippled
sand and low dunes on
floor at 600 m.

gully floors. Sand
contains an in-
creasing amount of
silt and clay with
depth. Sediment lies
at angle of repose on
steep gully walls and
moves onto gully
floor by creep and
gravity slides.

Pleistocene silt
rarely exposed and
few crustacean
burrows; widespread
sand sheet makes
burrow openings
difficult to
maintain.

5. Bioerosion by 5
crustaceans of
Pleistocene silt
exposed on lower
canyon walls is major
erosional process in
canyons; fine
sediment is most
thoroughly winnowed
from canyon sand in
larger canyons.

6. Large canyons: 6
bioerosion of lower
walls; accumulation
of mobile sand on
floor and winnowing
of fine sediment.

Small canyons: walls
draped with sand from
shelf, sand on floor
is less mobile and
contains more silt
and clay; similar in
some respects to
sedimentary
environment of upper
slope.

These observations suggest that within the outer shelf -upper
slope transition region the large canyons are chiefly sites of
erosion and transport of fine-grained sediment and of accumulation
of sand on the canyon floor, whereas deposition of both fine
sediment and sand is the most important process in the less
energetic, small canyons and on the seaward-facing upper slope.

Principally an
environment of
deposition; old
gullies incised into
Pleistocene silt are
draped with sand from
shelf; fine-grained
sediment increases
with depth.

234

ACKNOWLEDGEMENTS

This study was undertaken in cooperation with the National
Marine Fisheries Service. My colleagues and I appreciate the
efforts of the crews of the JOHNSON SEA-LINK submersibles (I and
II) and support ship R.V. EDWIN LINK, Harbor Branch
Oceanographic Institute, 1980-84; the NEKTON GAMMA and support
ship ATLANTIC TWIN, General Oceanographies, 1973-74; and the ALVIN
and support ship R.V. LULU, Woods Hole Oceanographic Institution,
1978, 1980, and 1982. Special thanks are given to NOAA's Office
of Undersea Research (OUR) , Rockville, Maryland, for their
continued support of our (National Marine Fisheries Service,
Northeast Fisheries Center) outer continental shelf living
resources and habitat programs, 1973-1985. I am grateful to Brad
Butman of the U.S. Geological Survey for sharing the results of
the Lydonia Canyon experiment with me.

LITERATURE CITED

Butman, B. , R.C. Beardsley, B. Magnell, D. Frye, J. A. Vermersch,
R. Schlitz, R. Limeburner, W.R. Wright, and M.A. Noble.
1982. Recent observations of the mean circulation on Georges
Bank. J. Phys. Oceanog. 12: 569-591.

Butman, B. , M.A. Noble, J. A. Moody, and M.H. Bothner. 1983.
Lydonia Canyon dynamics experiment: preliminary results.
In: B.A. McGregor (ed.), Environmental geologic studies on
the United States mid- and north Atlantic outer continental
shelf area, 1980-1982, vol. 3, North Atlantic region, chapter
8, p. 8-1 — 8-93. Final report to U.S. Bureau of Land
Management, U.S. Dept. of Interior.

Butman, B. , Pers. Comm. , 1984. U.S. Geol. Survey, Woods Hole, MA
02543.

Butman, B. , and R.C. Beardsley. In press. An introduction to the
physical oceanography of Georges Bank. In: R.H. Backus
(ed.), Georges Bank. Massachusetts Institute of Technology
Press, Cambridge, Mass.

Butman, B. , J.W. Loder, and R.C. Beardsley. In press. The seasonal
mean circulation: observation and theory. In: R. Backus
(ed.), Georges Bank. Massachusetts Institute of Technology
Press, Cambridge, Mass.

Carpenter, G.B., A. P. Cardinell, D.K. Francois, L.K. Good, R.L.
Lewis, and N.T. Stiles. 1982. Potential hazards and
constraints for blocks in proposed north Atlantic OCS oil and
gas lease sale 52. Minerals Management Service and U.S.
Geol. Survey Open-File Report 82-3 6, 51 p.

Cooper, R.A., P.C. Valentine, J.R. Uzmann, and R.A. Slater. In
press. Georges Bank submarine canyons. In: R.H. Backus
(ed.), Georges Bank. Massachusetts Institute of Technology
Press, Cambridge, MA.

Hotchkiss, F.S. and C. Wunsch. 1982. Internal waves in Hudson
Canyon with possible geological implications. Deep-Sea Res.
29: 415-442.

235

Keller, G.H. , and
processes in
States. In:
Sedimentation
chapter 2 , p

F.P. Shepard. 1978. Currents and sedimentary
submarine canyons off the northeast United
D.J. Stanley and G. Kelling (eds.),
in submarine canyons , fans, and trenches,
15-32. Dowden, Hutchinson, and Ross, Inc.,
Stroudsburg, Pa.
Moody, J., B. Butman, R.C. Beardsley, W. Brown, P. Daifuku, .D.
Irish, D.A. Mayer, H.O. Mofjeld, B. Petrie, S. Ramp, P.
Smith, and W.R. Wright. 1984. Atlas of tidal elevation and
current observations on the northeast American Continental
Shelf and Slope. U.S. Geol . Survey Bull. 1611, 122 p.
Southard, J.B., and D.J. Stanley. 1976. Shelf-break processes
and sedimentation. In: D.J. Stanley and D.J. P. Swift
(eds.), Marine sediment transport and environmental
management, chapter 16, p. 351-377. John Wiley and Sons,
N . Y .
Twichell, D.C. 1983. Geology of the head of Lydonia Canyon, U.S.
Atlantic Outer Continental Shelf. Mar. Geol. 54: 91-
108.

J.R. Uzmann, and R.A. Cooper. 1980. Geology and
Oceanographer Submarine Canyon. Mar. Geol. 38:

Valentine, P.C.,
biology of
283-312.

Valentine, P.C.,
topography,

J.R. Uzmann, and R.A. Cooper. 1984a. Submarine

surficial geology, and fauna of Oceanographer

Canyon, northern part. U.S. Geol. Survey Misc. Field

Studies Map MF 1531, 5 sheets.

Valentine, P.C., R.A. Cooper, and J.R. Uzmann. 1984b. Submarine

sand dunes and sedimentary environments in Oceanographer

Canyon. J. Sed. Petrol. 54: 704-715.

CHAPTER V

OCEAN SERVICES

NOAA Symp. Ser. for Undersea Res. 2(2), 1987 239

A POTENTIAL UNTETHERED ROV FOR OCEAN SCIENCE

D. Richard Blidberg
Marine Systems Engineering Laboratory
University of New Hampshire
Durham, NH

ABSTRACT

Untethered (autonomous) vehicles are not typically designed
to replace conventional tethered (remotely-operated vehicles) ,
however, freedom from the tether offers distinct advantages which
will allow free-swimming vehicles to serve as alternatives to
ROV's and manned submersibles. Advantages include, minimal
handling system reguirements, increased horizontal and vertical
range of operations, and reduced energy expenditure (no cable
drag) . Recent technology which has facilitated tether removal
includes the development of microprocessors, robotics, high
energy-density batteries, optical fibers, acoustic communication
(including telemetry) links, and strong lightweight materials.
Five autonomous vehicles in use and/or under development are
described: SPURV II. Epaulard. AUSS, EAVE-East. and ARCS.
Finally, a preliminary autonomous vehicle system concept,
formulated by the University of New Hampshire's Marine Systems
Engineering Laboratory (MSEL) , is presented. This system will be
designed to meet the needs of ocean scientists working
from small support vessels, at water depths of less than 500 m.

INTRODUCTION

Intelligent free swimming vehicles are the subject of
research and development efforts in at least 11 laboratories
throughout the United States and Europe. The research efforts are
focused on developing technology and prototype vehicles to perform
underwater inspection and light work tasks.

Remotely operating vehicles (ROV) , controlled from the end of
power and communication tethers, have proved to be successful in
many offshore applications. The vehicle carries sensors, imaging
sensors in particular, to convey information to a remote operator,
while manipulators serve as an extension of his hands. Some on
board computation is usually provided in the form of controllers.
An enviable record of success has been achieved with tethered
ROVs, and indeed, one may ask why attempts should be made to
remove the tether. Obviously an untethered vehicle has no access
to external power, and must carry the energy for the entire
mission on board. The mission duration is thus restricted and
only limited power is available for physical work. The
communication link, deprived of direct connection, becomes limited
indeed. Without access to an operator, the vehicle must itself
make crucial decisions to ensure its safety, and the success of
its mission.

It is apparent that the conventional ROV will continue to
serve with distinction in its prime areas of application.
However, as the range of operation becomes longer, and water
depth increases, the drag exerted by the tether becomes a major

240

limiting factor to operational effectiveness. The thrusters, and
therefore the vehicle, must become larger, the cable thicker, and
the energy that will go into overcoming cable drag will become a
limiting factor. Surface ship handling facilities must become
massive and the situation becomes self-limiting.

An untethered vehicle needs the same power at any depth.
Entanglement of the tether, a common concern in ROVs, is
eliminated. Surface ship handling systems become almost trivial.
Moreover, many classes of untethered missions have been recognized
which are essentially inspection and information gathering
functions where manipulation and heavy work are not required.
Many of the requirements of ocean science also do not demand
tethered systems. In addition, they offer relief from the expense
of the manned submersibles currently in use. In most of these
missions, the constraints of on board energy sources, therefore,
are not limiting factors, and all represent desirable applications
for an intelligent untethered robotic submersible.

Any considerations of removing the tether would have been
quite impossible before the advent of the microcomputer. Within
the past few years, however, new technologies have appeared which
offer much promise for greatly reducing the need for on-line
operator control. This technology — robotics — someday will
allow machines to be programmed in advance to perform specified
tasks, to reason, to communicate and to handle many complex
problems with on board intelligence.

At the root of this technology are microprocessors, chip-
sized computers, which can be arranged in large scale integrated
circuits to perform the various necessary computations and to make
key decisions. Together with other new developments, such as high
energy-density batteries, optical fibers, acoustic communication
links and strong lightweight materials, robotic submersible
development can begin in earnest. The successful development of
such vehicles (variously referred to as unmanned, untethered
vehicles, unmanned free swimmers, supervisory controlled vehicles,
or even autonomous vehicles) will provide alternative solutions to
the increasingly perplexing problems regarding effective
underwater inspection and work at minimum cost, improved
reliability, greater range and unlimited depth.

Following are capsule descriptions of some ongoing autonomous
vehicle developments:

SPURV II

Applied Physics Laboratory (APL) , University of Washington,
Seattle, Washington, has pioneered in the field of autonomous
vehicle systems since 1959 with the UARS (Undersea Arctic Research
Submersible) development in the 1960s and subsequent SPURV (self-
propelled underwater research vehicle) of the early 1970s. The
latest, called SPURV II, is an instrumentation platform for
oceanographic research. It became operational in 1975 and was
extensively modified in 1979.

241

Specifications :

Length - 4.57 m (15 ft)
Weight - 454 kg (1300 lbs)
Diameter - 50.89 cm (1.67 ft)
Maximum depth - 1500 m
Speed - to 3.0 m/s
Endurance - to 7 hrs
Propulsion - single 1 hp motor
Power - 2 3.25 kWh silver zinc battery

Payload - temperature, pressure, conductivity, sensors and
f luorometer

Navigation and control is provided by a shipboard operator
aided by an acoustic link. On-board operational sensors include
heading, depth and speed.

Epaulard

CNEXO (Centre National pour 1 ' exploitation des Oceans), La
Seyne sur Mer, France, has led the development of an operational
vehicle, the Epaulard, with a superb success record. The mission
is to conduct deep water bottom photography, and topographic
profiling studies. From its launch in 1979 to mid-1981, Epaulard
had 72 dives, 40 of them to depths of between 1000 and 5300
meters. The vehicle descends with a dive weight which is
discarded on the bottom, maintains altitude with a drag chain, and
discards an ascent weight to reach the surface. Its course is
controlled by an acoustic link from the surface.

Epaulard specifications include:

Depth - 6,000 m

Speed - up to 2.5 knots

Duration - 10 hours

Range - 12 nmi

Hull material - titanium

Length - 4 m (13.12 ft)

Beam - 1.1 m (3.6 ft)

Weight in air - 3 tons (2.730 kg)

Propulsion - 1 thruster with rudder steering

Power source - 18 kWh lead acid batteries

Command control - internal heading follower, acoustic command and

measurement
Computer - two 8080 and three UP141 microprocessors
Instrumentation - 35 mm, 5000 exposure still camera, temperature,

altitude, depth and heading.
Launch/Retrieval - A-frame or crane.

AUSS

Naval Ocean Systems Center (NOSV) San Diego, California, has
been developing the AUSS (advanced unmanned search system) . It
has four objectives relative to autonomous vehicle development.
They include:

242

Analysis to determine optimal means of conducting deep

ocean search.

A testbed for verification of deep ocean search

technologies .

Component and subsystem test and evaluation.

Development of a data acquisition system which explores

the optimal data gathering instrumentation.

The specifications of the AUSS include:

Hull - graphite cylinder with titanium endbells.

Length - 14 ft (4.27 m)

Diameter - 3 0 in (.7 6 m)

Displacement - 2000 lbs (969 kg)

Operating depth - to 20,000 ft.

Power - silver zinc batteries

Navigation - dead reckoning with doppler sonar transponder

positioning
Propulsion - two stern thrusters for foward motion and yaw

(turning) , two vertical thrusters for heave
Communication - vertical acoustic link, 4800 bits/sec. up link,

1200 bits/sec down link, bit error rate 1 in 100,000

EAVE-East

The EAVE-East (Experimental Autonomous Vehicle) is a testbed
for technology development. It has completed tests to demonstrate
the ability to autonomously follow an underwater pipeline and
maneuver inside an underwater structure using an on board, high
resolution (±10 cm) , acoustic navigation system. The current
emphasis is to develop a knowledge-based guidance and control
system.

EAVE-East Specifications include:

Size - 4 ' x 4 ' x 4 '

Weight - 750 lbs

Maximum depth - 1000 ft.

Speed - 2 knots

Endurance - 8 hrs

Propulsion - 6 - 0.25 hp thrusters

Power source - 2kWh (24, 16Vdc)

Payload - 50 lbs

Computer system - 2 - 6100, 2 - 68000, 1 - 9511

Navigation - short baseline/long baseline

Data storage - 2 56Kbyte magnetic bubble memory

ARCS

Bedford Institute of Oceanography (BIO) , Dartmouth, Nova
Scotia, Canada, has contracted with International Submarine
Engineers of Port Moody, British Columbia, to construct the ARCS
vehicle (autonomous remotely controlled submersible) . The diving
mission of the ARCS is to conduct bathymetric surveys in ice-
covered waters.

243

System specifications include:

Endurance - 100 nmi

Design depth - 1200 ft (366 m)

Speed - 5 knots for 2 0 hours

Maximum distance from a control station - 10 mi (16 km)

Torpedo shaped - length 15 ft (4.4 m)

diameter 21 in (53.3 cm)
Displacement -2200 lbs (1000 kg)
Sensors - bathymetric and ultimately seismic and sidescan sonar.

Sperry Cll gyroscope, depth, Doppler sonar.
Navigation - acoustic beaconry, accuracy of 5 m Oceano long

baseline system
Thruster - 1/2 hp electric motor
Battery - 110 Ah, 12 0 V nickel cadmium
Controllable - out to 5 miles in 100 feet of water
Status - prototype sea trials planned in late 1983.

These programs are by no means the only efforts directed at
the utilization of unmanned untethered submersible vehicles. The
Marine Systems Engineering Laboratory at the University of New
Hampshire has held a series of symposia directed at this
technology. Most of the other programs are described in the
proceedings from these symposia (the third was held June 6-9,
1983) .

The Marine Systems Engineering Laboratory (MSEL) has been
considering an unmanned untethered system which would be directed
at the needs of the ocean scientist using a small support ship
working in relatively shallow water (500 meters) similar to many
of the programs in the Gulf of Maine. Much of the research and
development program at MSEL over the past eight years has been
directed toward the robotic sciences and technologies as applied
to underwater and oceanic systems. The EAVE-East vehicle system
described above has been used as a testbed for the development of
technologies pacing the utilization of unmanned untethered
submersible systems. Current efforts have addressed the problems
of placing interactive intelligence on the vehicle. As this level
of intelligence increases, the potential of unmanned untethered
vehicle systems will increase dramatically.

Building on the experience gained from the development of the
EAVE-East vehicle, a preliminary vehicle system concept for
coastal and continental shelf missions (0-500 m) has been bounded.
This system is meant to compliment the capabilities provided to
ocean science by systems such as manned submersibles and remotely
operated, tethered vehicles.

The proposed untethered vehicle system would address the
following constraints:

Suitability for use on small support ships

The system would be usable from a support ship no larger than
40-50 feet. It would require only a simple A-frame capable of
placing 1000 lbs into the water. The control console for the
system must be small enough to be easily placed on the support
ship.

244

Easily transportable to a user location

In order to minimize the logistics problems which limit the
use of ROVs and, more substantially, manned submersibles, the
proposed system must be easily transported. The entire system,
with its support equipment and a reasonable inventory of spare
parts must fit into a van or similar container.

Reprogrammed in high level languages

It is important that much of the system software be
transparent to a user. Modification of the system to specifically
meet the user's specific needs is, however, very important. This
can be accomplished by incorporating into the system software,
high level language commands which drive specific vehicle system
functions. Experience with the EAVE-East vehicle has proven the
effectiveness of this concept (i.e. "hover", "go to point
x,y,z", "take 10 pictures", etc.).

Simple Sensors/Tools

There are many tasks which can be accomplished with
relatively simple/standard sensors or tools. It is felt that a
camera system (35 mm, CCD) and a 1 or 2 function manipulator will
offer substantial capabilities without complicating an initial
system design. Future enhancements to the sensor/tool suite are
anticipated, however, initial design efforts must emphasize
simplicity and reliability. Operational experience with such a
system will define and justify future changes. Within the
constraints imposed on this system it is possible to consider some
generic tasks which may well be addressed by an autonomous
system.

Sensor Driven Search/Survey

There is much interest in the small scale spatial patterns of
plants and animals if we are to understand the fundamentals of
ocean productivity. Also of concern to chemical and physical
oceanographers is the question of discontinuities and three
dimensional gradients. This time-varying data is estimated only
poorly by scattered vertical casts. It is possible to consider an
untethered vehicle mapping such parameters in three dimensional
space using on board sensors to determine its search. As the
parameter of interest decreases along a specific path, a decision
would be made to follow a different path which, from on board
sensor data, is determined to be within the volume
containing the parameter of interest.

Long term bottom monitoring

Without a tether it is possible to direct a submersible to a
specific location on the bottom. Once at that location it would
be possible to turn off the power consuming system components in
order to become a long term, precisely positioned, instrument
package.

Midwater studies

Again, due to the lack of a tether it is possible to maintain
a relatively stable position in midwater, offering opportunities
for midwater observation and sampling.

245

Visual Inspection

Much work recently has led to the ability to transmit video
images through an acoustic telemetry link. This technology allows
an untethered vehicle to be used as an observation tool. Although
a normal TV picture (30 frames/sec) will not be available, it is
possible to obtain reasonably real-time TV pictures (4 frames/sec)
from an acoustic telemetry link.

Instrument recovery, implantment, maintenance

The man-years of wasted effort and loss of much desired data
due to lost instruments are devastating to a program's goals. An
untethered vehicle with its accurate manuevering capability
(unhampered by tether drag forces) could home in on a mooring
(instrumented with a simple beacon) and aid in instrument
recovery. Some estimates place the cost of instruments lost in a
single year above the cost for development of an untethered
vehicle.

These tasks are meant only as a sample of the uses for an
untethered system. They are certainly not meant to be all
inclusive, however, they do help to bound the conceptual design of
two versions of an untethered vehicle which supports ocean
science.

An untethered unmanned submersible for ocean science

The following system characteristics are being considered as
a conceptual starting point for a vehicle system.

Vehicle — open space-frame structure (crab-like)

Weight — approximately 1000 lbs.

Characteristic dimensions — 3-4 ft

Duration — 10 hours

Navigation — +4" over 500' range, +l-3m over 5 km

Sensors/tools :

acoustically transmitted video

35 mm camera remotely or automatically controlled

simple tool (1-2 function claw)
Major system components:

shipboard control station

dockside support van

vehicle system

The driving purpose for considering an untethered system lies
with its potentially low cost, its ease of handling and limited
burden placed on the supporting vessel. The extraordinary
advances in subminiature computers, in practical applications of
artificial intelligence, and the improvements in the acoustic
link, open substantial potential for achieving relatively
sophisticated missions. This technology, though in its infancy,
shows potentially wide application as a tool for the ocean science
community.

NOAA Symp. Ser. for Undersea Res. 2(2), 1987 247

THE MONITOR NATIONAL MARINE SANCTUARY - IN PERSPECTIVE1

Mr. Edward Miller
NOAA Sanctuary Programs Division, Office of Ocean and Coastal
Resource Management, National Oceanic and Atmospheric
Administration, Washington, D.C.

ABSTRACT

Experience gained in the management of the MONITOR National
Marine Sanctuary has assisted the Sanctuary Programs Division of
the National Oceanic and Atmospheric Administration (NOAA) in
development of a Management model that recognizes historic
shipwrecks as an irreplaceable and non-renewable marine resource.

Building upon the data base of previous ship recovery
projects, and similar to the framework used for other fragile
"living" marine resources such as coral reefs and fish habitats,
the model focuses on the decision making process that emphasizes a
balance between the protection and wise use of the resource for
the maximum benefit of the American public.

INTRODUCTION

The announcement in 1974 that the wreck site of the USS
MONITOR had finally been located some sixteen miles south-
southeast of Cape Hatteras, North Carolina concluded more than 2 5
years of intrigue surrounding the whereabouts of the famous
ironclad. Due to the MONITOR'S legendary engagement with the
MERRIMACK (CSS VIRGINIA) in the first battle between ironclad
warships during the American Civil War, and it's subsequent loss
in the "Graveyard of the Atlantic" a short while afterwards, the
discovery of the wreck was generally regarded as some sort of
"prize" by the various search groups looking for it. In 1953,
The U.S. Navy had formally abandoned the vessel, relinquishing all
claims to the wreck so as not to impede private interests in the
search and eventual salvage of the vessel should the wreck be
located (Fogler, 1953) . As a result, numerous competing groups
sought to locate the ironclad in what the Navy Supervisor of
Salvage referred to as the "Great MONITOR Sweepstakes" (Searle,
1968) .

It should not have been surprising, therefore, that the
relentless enthusiasm for the MONITOR spilled over into the
ensuing intense and sometimes heated debate over what would be
done with the wreck now that it had been found. The arguments
spanned a spectrum from those calling for immediate recovery by
some eager to assert their "salvage" claim, to those calling for
the wreck to be left undisturbed in the natural environment.

1. NOAA Management Rep. Series, July 1984.

248

NATIONAL MARINE SANCTUARY PROGRAM

The question of what would be done with the wreck, and in
particular the issue of the desirability of salvage, had remained
moot as long as efforts to locate the wreck were unsuccessful.
However, with the wreck's discovery, the natural shroud of
protection had been stripped away and an immediate concern arose
as to the best method to protect it from relic hunters and
disjointed recovery efforts.

Soon after discovery, a meeting in Washington, D.C.
(Department of the Interior, 13 May 1974) between concerned
government agencies and universities determined that due to the
site location 16 miles S.S.E. of Cape Hatteras,it was beyond the
jurisdiction of the State of North Carolina and that other
existent federal laws did not adequately protect the site. The
need for such protection was dramatically underscored by a press
report of a dredging incident in an attempt to recover artifacts
that same month (Ringle, 1974) .

As a result, it was the concensus that provisions under a
newly established law, Title III of the Marine Protection,
Research, and Sanctuaries Act of 1972 afforded the best protection
for the wreck. Subsequently, the site was nominated by the
Governor of North Carolina and after a process of review and
public hearings, was designated as the nation's first marine
sanctuary by the Secretary of Commerce on January 30, 1975, the
113th anniversary of the vessel's launching.

Title III of the Marine Protection, Research and Sanctuaries
Act of 1972 authorizes the Secretary of Commerce, with
Presidential approval, to designate ocean waters from the
shoreline to the edge of the continental shelf, including the
Great Lakes, as marine sanctuaries for the purpose of preserving
their distinctive conservation, recreational, ecological,
cultural, and esthetic values. This was interpreted to include
historic or cultural remains of widespread public interest such as
the MONITOR. The National Marine Sanctuary Program is managed by
the Sanctuary Programs Division of the National Oceanic and
Atmospheric Administration (NOAA) .

The mission of the program is to establish a system of
national marine sanctuaries based on the identification,
designation, and comprehensive management of special marine areas
for the long-term benefit and enjoyment of the public.

The overall goals of the National Marine Sanctuary Program
are to:

1. Enhance resource protection through the implementation of
a comprehensive, long-term management plan tailored to the
specific resources.

2. Promote and coordinate research to expand scientific
knowledge of significant marine resources and improve management
decision making.

3. Enhance public awareness, understanding, and wise use of
the marine environment through public interpretive and
recreational programs.

4. Provide for maximum compatible public and private use
(NOAA, 1982A,B) .

249

The program ensures a balanced and comprehensive approach to
the protection and wise use of selected marine areas. The program
is not limited to regulating particular marine-related activities
or protecting singular resources, but includes non-regulatory
provisions for identifying and comprehensively managing marine
areas based on their various resource and human use qualities.
The focus is on developing coordinated research programs to
evaluate and monitor the overall condition of the resources and to
assess the cumulative impacts of all activities affecting them.
The program also provides an educational and informational service
to increase public awareness and understanding of the value and
importance of marine resources (General Accounting Office, 1981) .

The program represents an innovative approach to ocean
management; one based on planning, analysis, and decision making
that promotes multiple use of resources while offering protection
by recognizing the interplay of human activities and the natural
environment. When conflicts are identified between conservation
and resource use, a management strategy is developed that assures
a decision that produces the maximum social benefit.

For nearly 100 years the United States has recognized the
importance of special areas of it's public lands. Yet these
efforts have been directed almost exclusively to terrestrial areas
above the high water mark of the oceans and Great Lakes, largely
ignoring the more than 4 3 percent of the nation's public lands
which lie offshore (Blumm and Blumstien, 1978) .

The Program represents a mechanism for reversing this "out-
of-sight, out-of-mind" attitude toward the marine environment and
for actively promoting marine resource management. It provides a
means to protect marine resources and promote comprehensive
management in a manner similar to that used for our land-based
resources. From the standpoint of resource protection, public
use, and public awareness, the program mission offers a corollary
to well-established terrestrial programs in that special marine
areas are managed for public use and benefit in concert with
resource protection (NOAA, 1982A) . The protection of a historic
shipwreck within the same general management framework used for
other fragile, "living" marine resources such as coral reefs and
fish habitats provides a sound scientific basis for learning how
to treat this important, yet little understood, marine resource.

HISTORIC SHIPWRECKS AS MARINE RESOURCES

Throughout history, the ship has traditionally been one of
the largest and most complex machines produced by man. As such,
the ship and it's contents present a discernable "finger print" of
the society that produced it and can reveal a great deal of
information about the people who constructed it.

A ship is built for a specific purpose at a distinct point in
time. The ship and it's contents were specifically selected for a
narrowly defined purpose and designed to be self-sufficient and to
maintain a shipboard community for extended periods of time
(Lenihan, 1983) . The decisions made by the builders with regard
tothe design, selection of materials, and method of construction
paints an accurate picture of their technology and industry, while

250

the ship's contents reveal a great deal about their economy,
society, and culture.

Normally, this transient record is dispersed at the end of
the last voyage when the cargo is sold, the crew returns to their
homes, and the ship is eventually broken up. It is only with the
event of a shipwreck that the whole unit - ship, cargo, and
shipboard community - is deposited on the seafloor, creating a
material record that is archaeologically recoverable (Muckelroy,
1978) .

The value of the archaeological record is that it is a more
direct source of evidence about a specific ship than any other
form of historical data. While it is subject to the
interpretations of the archaeologist, other sources such as the
documentary or the pictorial are subject to two such filters, that
of the contemporary recorder and that of the modern interpreter.
The fact that the deposition was totally accidental and
unintentional increases the significance in that the remains show
what actually existed, rather than what was thought to be there,
or should have been there at a somewhat random point in time
(Muckelroy, 1978) . The study of a shipwreck provides an
invaluable opportunity from several disciplinary perspectives to
study the physical remains of man's activities on the sea, in many
instances, remarkably well preserved and relatively undisturbed by
the marine environment.

The scope of the science of marine archaeology is inherently
linked to the potential and to the limitations of the marine
environment, both as a medium for the preservation of remains, and
as the physical setting in which fieldwork is undertaken
(Muckelroy, 1978) .

The potential for the preservation of material beneath marine
sediments was recognized as early as 1832 when Charles Lyell, a
pioneer in geology, concluded that "it is probable that a greater
number of monuments to the skill and industry of man will in the
course of the ages be collected together in the bed of the ocean,
than will exist at any one time on the surface of the Continents"
(Muckelroy, 1978) .

The physical limitations posed by the marine environment are
directly related to man's development of the necessary technology
for it's exploration, beginning with the invention of SCUBA in
1942, and the development of the proper tools and methodology to
conduct archaeology at depth, beginning with the pioneering work
of Dr. George Bass in 1960.

A historic shipwreck should be viewed as a valuable marine
resource of primary source data on man's maritime activities that
is not available elsewhere. The potential of this resource is
restrained only by our technology and our attitudes towards it's
value and use. The study of this marine resource will constitute
an important element in the search for a greater understanding of
man's past and merits careful management to assure maximum benefit
from it's utilization.

An undisturbed shipwreck has been described by archaeologists
as a "time capsule" containing a microcosm of historical and
cultural information frozen in time at the instant the sinking
occurred. The excavation of a submerged site has been likened to

251

"an irreversible and unrepeatable scientific experiment" that is
inherently destructive of the resource and justified only with
thorough documentation and reporting (Morrison, 1981) . The
awareness that a submerged archaeological site is an irreplaceable
and non-renewable marine resource fosters the recognition that the
"prize" of discovery is, in reality, a burden of responsibility to
properly protect and preserve the resource and to assure it's wise
use.

The act of discovery of historic shipwrecks in the past has
all too often resulted in their eventual destruction. Whether
this has been due to the lack of knowledge on how to deal with
submerged sites or due to misplaced motivations toward some sort
of "reward" for the often-times considerable effort required to
locate a wreck, is of little consequence when one considers the
loss of information in archaeological or historical terms.

Should excavation and the recovery of submerged material be
selected as the appropriate option, then there must be a keen
awareness of the extent of the responsibility to provide for the
proper documentation, conservation, publication of results, and
perpetual care of the artifact collection, if there is to be any
lasting value to the project.

To a very large extent, the effectiveness of the conservation
effort will determine how the success of the entire project is
perceived. If recovery of material is undertaken, the project
must be sustained through the lengthy conservation and display
phases. However, if financial support wanes due to unforeseen
costs or decreased public interest and the conservation is stopped
due to lack of funds or inadequate technical capability, the
entire project may be placed in jeopardy. There must be no
hesitation in the commitment to follow through with the
conservation, interpretation , final reporting, and long-term
curation once excavation begins, if maximum value is to be derived
from the resource.

If a ship can be described as a microcosm of a past society
that produced it and warrant meticulous documentation in it's
study and preservation as a shipwreck, then it is not superficial
to suggest that a project to study, excavate, and possibly recover
a shipwreck represents a microcosm of the society conducting it in
terms of it's human values, cultural behavior, and allocation of
resources and, therefore, merits equal consideration. In the
final analysis, the manner in which the resource is managed and
the solutions offered will determine the ultimate value of a
project, and to a large extent, the quality of the endowment in
cultural heritage left to succeeding generations.

Few individuals can fully appreciate the type of commitment
and the level of investment in terms of time, effort, knowledge,
and money often required to record, excavate, and secure the
physical recovery, conservation, and long-term curation of
material from underwater sites. Any project considering the
recovery of an historic shipwreck should carefully study the
Scandanavian experience with the WASA and the recent British
experience with the MARY ROSE in comparison to the U.S.
experience with the Cairo.

The WASA is a remarkably well-preserved 1628 Swedish warship
recovered intact from Stockholm Harbor in 1961. This project

252

serves as a primary model for all other ship recovery projects.
It was the first project of this type and scale ever attempted and
as a result, much of the present technology for the conservation
of submerged materials was developed during this project.
Since there was no previous experience of the same scale with
which to compare, many decisions were made without the full
knowledge of what the consequences would be in terms of results or
final costs. Several important lessons can be learned from this
project.

First, once the decision is made to recover, there must be
total commitment to conservation in terms of stable and sufficient
financing. Economic factors should not be allowed to determine
when the conservation process is complete. Second, an
internationally significant project of this magnitude requires
support from the general public as well as government
institutions. Lastly, the preservation of the ship equates to
perpetual care and maintenance, if the ship is to be a lasting
artifact. The WASA has been undergoing conservation treatment for
over 2 5 years (Barkman, 1978) .

A more recent example is the 1545 Tudor warship MARY ROSE
recovered in 1982 from 40 feet of water near Portsmouth, England.
What started in 19 65 as archaeological explorations to survey,
record, and, if possible, identify an unknown anomaly using
amateur divers turned into a seventeen year effort to completely
document, excavate, and finally recover the remaining ship
structure at a cost of nearly $7 million, supported largely by
private donation (Rule, 1982) .

The MARY ROSE Project is a management model from the
standpoint that it reveals the intricate multi-disciplinary nature
of ship recovery projects that transcends normal disciplinary
boundaries. The project demonstrated the essential requirement
for strong management closely controlling all aspects of the
project encompassing archaeology, conservation, engineering,
museology, and a host of other supporting disciplines and
specializations, the most important being fund raising.
The highly publicized and exciting work of the discovery of
artifacts and the recovery of the hull is completed. Now efforts
are concentrated on sustaining the project through the lengthy
conservation and display phases estimated to take another 2 0 years
(Clark, 1983) .

From the archaeological perspective, it seems unfortunate
that only the relatively short, high-risk recovery phase is
sufficiently spectacular to generate the crucial money and
enthusiasm. In comparison, the slow toil, long-term effort, and
considerable expense of adequate recording, conservation, and
formal publication appear lackluster and as a result receive
little public attention and, in many cases, lack the necessary
planning and support (Morrison, 1981) .

A lamentable example is the case of the USS CAIRO, a Civil
War gunboat discovered virtually intact and well-preserved in 1956
near Vicksburg, Mississippi. The best intentions motivated by
local pride, enthusiasm over the find, and lack of continuity of
personnel combined to create a catastrophic loss of information
and material in archaeological and historical terms (McGrath,
1981) . Poor planning for the recovery resulted in the wreck being

253

virtually torn apart during the lifting operations. This was
later compounded by the complete absence of any planning for
conservation and the lack of anticipated funding to support the
project (McGrath, 1981) . Although the National Park Service has
done an admirable job of "salvaging" what otherwise would have
been a complete loss, the "Hardluck Ironclad" is a mute reminder
of what can happen to an ill-conceived and hastily executed ship
recovery project.

The principle danger to the surviving archaeological record,
in most instances, is from excavators and salvors who in the
process of uncovering material, disrupt the tenuous equilibrium
between preservation and deterioration. This awareness places
great emphasis on the need for planning that encompasses not only
the engineering of recovery, but also the conservation, curat ion,
and display of recovered artifact collections. It has too often
been the case, that the damage in the recovery and the subsequent
treatment of material has exceeded all previous damage suffered
by the object during it's entire existence (Peterson, 1978).

The greatest benefit from studying previous projects is that
they formulate an essential data base of collective knowledge,
maturing attitudes and developing experience on how to properly
treat historic shipwrecks. A shipwreck should not be excavated
just because it is discovered (Bass, 1978) and most certainly,
recovery is not the proper answer in every case. How is this
decision made? Who should be involved? What minimum standards of
historical and archaeological documentation should be required?
How should the projects be financed?

The MARY ROSE example clearly shows that the successful
project includes many diverse elements and requires the careful
cross-pollination of numerous disciplines. How the essential
cooperation between various government agencies, different
professionals and amateurs is elicited, and the crucial outside
support is orchestrated, so that the collective "project"
succeeds, is a harmonious melody that has so far eluded the United
States, the difference between the CAIRO Project and the MARY
ROSE Project was not a matter of luck, but rather of design
through policy, management, and planning.

The National Marine Sanctuary Program is building upon the
experience of past projects, hoping to provide similar elements of
success for the management of the MONITOR National Marine
Sanctuary, both as a suitable requiem to the "little cheesebox-on-
a-raft" and to serve as a national model for the treatment of
historic shipwrecks, thus adding another first to the already
long list of firsts for this famous ironclad. As such, the
concentration is not on the question of the recovery of the vessel
per se, but on the process of arriving at the decision of what
should be done with the shipwreck, recognizing that the answer to
the first question lies in the understanding of the second.

MONITOR NATIONAL MARINE SANCTUARY

Since the discovery of the MONITOR in 1973 and it's
subsequent designation in 1975 as the nation's first National
Marine Sanctuary, an abundance of conflicting viewpoints have been

254

expressed about the ultimate disposition of the wreck.

Due to the interaction of a great number of people, a
philosophical basis has emerged on how to deal with the site. The
fundamental premise is that the MONITOR is an archaeological site,
and due to the ship's historical significance, and the high public
interest in it, the project warrants careful and deliberate
planning so that a maximum return and benefit can be derived for
the American public (Smithsonian Institution, 1976) . In addition
to maintaining site integrity for scientific research, equal
emphasis was placed on maintaining recovered artifacts,
documentation, and other MONITOR-related materials intact as a
single collection to be made available to researchers and the
public (NOAA, 1974) .

At a National Conference held in 1978, the focus was set on
the fundamental question of what should be done with MONITOR, in
contrast to what we can or want to do. Thus a significant
emphasis was placed on the process of decision making in order to
insure the maximum benefit for the American people, without
degrading the historical and archaeological value of the site.
This same approach was recommended for other historic shipwrecks
including the USS TECUMSEH, BROWN'S FERRY, and other historic
vessels whether currently known or yet to be discovered (National
Conference, 1978) .

Additionally, there was general consensus that more research
and information about the environment and it's impact on the
material condition of the wreck were necessary before any decision
could be made about the ultimate disposition of the MONITOR, if it
is to be treated in a scientific and technologically sound manner
(National Conference, 1978) .

It was recommended that the decision concerning what should
be done with the MONITOR is ongoing, accompanied by a research
program consisting of assessments and evaluations structured to
determine the technical and fiscal feasibility of management
options ranging from non-disturbance of the site to complete
recovery of the wreck. The objective of research is to determine
as far as technologically possible, what is fact concerning the
actual condition of the wreck, to avoid decisions based on
speculation.

The understanding of what is, and not what we hope or would
like to to be, is the fundamental issue underlying the development
of any responsible and appropriate management option concerning
what, if anything, should be done at the MONITOR site.

The following goals have been established for the Sanctuary:

To protect and preserve the MONITOR and all it's associated
records, documents, and archaeological collections.

To insure the scientific recovery and dissemination of the
historical and cultural information preserved at the MONITOR
site; and to preserve and develop the physical remains of the
MONITOR in a manner which appropriately enhances both the
significance and interpretive potential of the vessel.

255

To enhance public awareness and understanding of the MONITOR
as a historic and cultural resource by providing interpretive
educational services and materials (NOAA, 1982A,B).

Future proposals for on-site work will be evaluated for their
potential adverse impact on the resource by using the
following criteria:

SUITABLE - Does the proposal support the goals of the
Sanctuary?

FEASIBLE - Are the available resources adequate and do they
provide assurance for the proper documentation,
recovery, conservation, reporting, display, and
perpetual care of any recovered artifacts?

ACCEPTABLE - Is the cost of accomplishing it worth the

expected results?

Since the designation in 1975, NOAA has sponsored three major
expeditions to the Sanctuary. The most extensive investigation
occurred in 1979 when a team of archaeologists conducted 49 dives
in 2 6 days from a lock-out submersible. The major accomplishment
was the completion of a test excavation to collect archaeological
samples and engineering data to evaluate the extent of the
archaeological record and the condition of structural members
buried by bottom sediments. The explorations were also history
making, being the deepest archaeological excavation conducted by
archaeologists to date in the United States.

The experience gained in developing the proper methodology
and new techniques for working in 22 0 f.s.w. has been extremely
rewarding in developing new approaches and tools for deep water
archaeology. Additionally, the information collected by the
diver/archaeologists first hand is vastly superior to the quality
and quantity of other substitute remote methods currently
available today.

Perhaps most germane to our understanding of the interaction
of the wreck with the environment have been the results of the
static equilibrium analysis. This study concluded that sections
of the armor belt and adjacent exterior hull may be stressed close
to their ultimate strength, and have already shown indications of
plastic yielding (Muga, 1982) .

A corollary study that compiled and analyzed what is
presently known about the effects of the environment on the rate
of deterioration concluded that the MONITOR is continuing to
deteriorate from natural galvanic corrosion due to it's continued
exposure to the marine environment. Unlike other historic
shipwrecks that have been well-preserved due to a protective
covering of marine sediments, the MONITOR (Figure 1) has, in all
likelihood, been exposed most of it's history as a shipwreck to an
environment characterized as highly corrosive due to the
temperature, oxygen content, and current velocity (Miller, 1984) .

This dynamic type of environment, as opposed to one that is
static and anoxic and therefore conducive to preservation of
materials, adversely affects the structural fabric due to two

256

Figure 1. The hull of the MONITOR lies inverted and resting upon
the displaced turret, placing severe stress on the major
longitudinal support member, the port armor belt.

primary mechanisms. The relatively high velocity bottom currents
transport abrasive bottom sediments which effectively erode the
protective encrustation built-up by corrosion by-products that
normally tend to gradually decrease deterioration over time. As a
consequence, exposed material surfaces have received less
protection from the insulating effect of corrosion by-products
than would be expected compared to other sites.

This adverse mechanism is compounded by the continuous flow
of relatively warm, highly oxygenated sea water which supplies a
virtually infinite supply of ions which "feed" the corrosion
reaction with the detrimental effect of accelerating the rate of
corrosion of exposed material compared to similar material buried
by bottom sediments. Thus, the natural environment has been a
major factor in the extensive structural deterioration recorded as
a result of over 120 years of submersion in sea water (Miller,
1984) .

The analysis of these finding identifies a significant threat
of collapse to the remaining historic structure of the vessel due
to the unequal and highly stressed support provided by the
displaced turret. Over one-half of the existing structure is
presently being supported above the bottom by the turret (Watts,

257

1982) . Due to the structural loadings imposed on the
longitudinal members, there is a high probability that the
structure will fail and collapse in the near-term (Miller, 1984) .

This eventuality will adversely impact the resource by
substantially increasing the rate of deterioration of the
remaining ship fabric by exposing newly fractured material
surfaces to the corrosive environment. Additionally, the collapse
of the intact structure will seriously degrade the archaeological
and historical value of the site by disrupting the engineering
spaces of the ship which are a high interest/value area for future
investigations (Miller, 1984) .

The full impact of this threat is being further evaluated and
future research efforts will attempt to refine and better quantify
the measurement of residual strength and degree of strain in
critical structural members. The report concludes; "The
management option of 'no action' does not appear to be justifiable
for the MONITOR National Marine Sanctuary as it risks the eventual
loss, rather than assuring preservation, of the valuable cultural
resource it was established to protect" (Miller 1984).

Whether or not any reasonable action can be taken to mitigate
this threat is presently unknown. Several alternative management
options are being assessed. Regardless of the outcome, however,
this methodical scientific approach to the management of the
resource has facilitated a quantum leap in our appreciation and
understanding of a historic shipwreck as a valuable marine
resource.

The management framework developed for the MONITOR provides a
suitable safeguard to assure that the MONITOR question is
approached in a scientifically sound manner and also provides
sufficient latitude for the opportunity to develop the necessary
research and management tools to preserve and properly utilize the
MONITOR within the context of a management model for submerged
cultural resources. The strategy to date has been successful in
that the MONITOR still lies intact and protected within the
Sanctuary.

Future strategies will insure decisions based, not on
speculation and emotion, but on scientific method and research,
building upon the existent data base on how to treat historic
shipwrecks and assure the adoption of a plan that fulfills the
promise of establishing a national cultural policy for historic
shipwrecks in the United States.

LITERATURE CITED

Barkman, Lars, 1978. The Management of the Historic Shipwreck
Recovery and Conservation as Experienced from the WASA. In:
National Conference. The Monitor, it's Meaning and Future,
p. 101-112, National Trust for Historic Preservation,
Washington, D.C.

Bass, G.F., 1978. The MONITOR, An Archaeological Venture. In:
National Conference, The MONITOR, It's Meaning and Future, p.
123-125, National Trust for Historic Preservation,
Washington, D.C.

258

Blumm, M.C. and J.G. Blumstein, 1978. The Marine Sanctuaries

Program: A Framework for Critical Area Management in the

Sea, 8 Envt'l Law Rep 50016-50018.
Clark, J., 1983. The MARY ROSE Project, Personal Communication

Department of the Interior, May 13, 1974. Meeting of Federal

Agencies on Legal Status and Protection of MONITOR.
Fogler, R.H. Sept. 30, 1953. Recommendation for Abandonment of

USS MONITOR, Official Correspondence, Secretary of the Navy.
General Accounting Office, 1981. Marine Sanctuaries Program

Offers Environmental Protection and Benefits Other Laws Do

Not, Report by Comptroller General of the United States, CED-

81-37.
Lenihan, D. J. , 1983. Rethinking Shipwreck Archaeology: A

History of Ideas and Considerations for New Directions.

Shipwreck Anthropology, p 37-64. School of American

Research, New Mexico.
McGrath, H.T., 1981. The Eventual Preservation and Stabilization

of the USS CAIRO. International Journal of Nautical

Archaeology. (2):79-94.
Miller, E.M. 1984. The Rate of Deterioration of the USS MONITOR,

it's Measurement and Impact. Technical Report Series,

Division of Archives and History, Raleigh, N.C. (in press).
Morrison, I. A., 1981. International Journal of Nautical

Archaeology (2) .
Muckelroy, K. 1978. Maritime Archaeology, Cambridge University,

Press, London, U.K.
Muga, B. J. , 1982. Engineering Investigation of the USS MONITOR.

Technical Report Series, Division of Archives and History,

Raleigh, N.C.
National Conference, 1978. The MONITOR, It's Meaning and Future,

Conference Resolution, National Trust for Historic

Preservation, Washington, D.C.
National Oceanic and Atmospheric Administration, 1974. MONITOR

National Marine Sanctuary Final Environmental Impact

Statement. Sanctuary Program Division, NOAA, Washington,

D.C.
National Oceanic and Atmospheric Administration, 1982A. National

Marine Sanctuary Program Development Plan. Sanctuary

Programs Division, NOAA, Washington, D.C.
National Oceanic and Atmospheric Administration, 1982B. MONITOR

National Marine Sanctuary Management Plan. Sanctuary

Programs Division, NOAA, Washington, D.C.
Peterson, C.E., 1978. Conservation Systems. In: National

Conference, the MONITOR, It's Meaning and Future, p. 91-98.

National Trust for Historic Preservation, Washington, D.C.
Ringle, K. , 1974. MONITOR'S SOS Unheeded, Geologist Tears Into

Sunken Wreck of Ironclad. Washington Post, Washington, D.C.

(Aug. 25) .
Rule, M. , 1982. The Raising of the MARY ROSE, The Illustrated

London News, London, U.K. (Oct.): 4 3-46.
Searle, W.F., 1968. Ltr. to Vadm. Eller, Historian of the Navy,

Official Correspondence, Dept. of the Navy.

259

Smithsonian Institution, 1976. National Conference to Develop
Philosophical Basis for Managing the MONITOR National Marine
Sanctuary, Adopted Resolution, Jan. 16, 197 6, Washington,
D.C.

Watts, G.P. 1982. Investigating the Remains of the USS MONITOR,
Final Report on 1979 Site Testing in the MONITOR National
Marine Sanctuary, Division of Archives and History, Raleigh,
N.C.

NOAA Symp. Ser. for Undersea Res. 2(2), 1987 261

CHAPTER VI. DEFINITION OF
NURP-UCAP SCIENCE PROGRAM

The following outline presents the missions, objectives, and
milestones of NURP-UCAP. This science program was defined during
the course of several workshops and many seminar-discussions with
scientists, regional coordinators, and program managers for
the northern New England (Region I) , southern New England (Region
II) and Great Lakes (Region III) areas of the northeast during
1984, 1985, and 1986. Mission and objective inputs come from
academic, government, foundation and industry participants in the
NURP-UCAP program, representing 12 states, 18 universities, 5
government agencies and a commercial-recreational fishing industry
valued at approximately $5 billion annually. A major
organizational and philosophical goal of NURP-UCAP is to maintain
a science program that demonstrates a blend of basic and applied
research that is multidisciplinary in scope and long term. A
rapidly increasing portion of the NURP-UCAP science program is
being directed towards experimental/process oriented research.

I . Mission - Conduct Biological, Geological, and Technical
Research to Improve Living Resource (Stock) Assessment
for Fisheries Conservation and Management.

A. Objective - Evaluation, refinement, and calibration of
sampling survey gear (trap, gillnet, trawl, dredge) used
for stock assessment.

Milestones

1. Evaluation of gillnet fishing behavior

2. Evaluation of scallop and clam dredge behavior

3. Evaluation of otter trawl ("rock hopper" and
"standard") behavior

4 . Evaluation of camera sled

5. Evaluation of remote operated vehicles (ROV's)

B. Objective - Greater information on distribution, habitat
preference, abundance, migratory behavior, feeding
behavior, predator-prey relationships, inter-specific
competition for food and shelter, reproduction and nursery
ground identification.

Milestones

1. Produce "Pictorial Atlas" on ecology, behavior, and
habitat preference for western North Atlantic
(continental shelf of New England, southern New
England and Mid-Atlantic Bight) . Summarize 25 years
of research (state, federal and academic) on the
northeast continental shelf.

262

2. Identify feeding, spawning, and nursery grounds
important to survival of selected marine and fresh
water species (cod, haddock, hake, herring, sea
lamprey, lake trout, lobster, shrimp, etc.) including
several apex predators (tuna, marine mammals) .

3. Produce basic life history information on selected
marine and fresh water species that cannot be studied
effectively from surface research vessels. Included
are in-situ depth and site specific studies directed
at predator-prey relationships and inter-specific
competition for food and shelter.

4. Water column ecology - identification of pelagic
fauna characteristic of water masses, vertical
migrations, predation on fish eggs and larvae,
delivery of organics to the benthic boundary layer,
mechanisms of survival and reproduction, etc.

5. Identify environmental factors governing shellfish
(quahog, surf clam, scallop, lobster) recruitment
(survival, growth), with the initial emphasis directed
towards the coastal and estuarine environments.

C. Objective - Improve monitoring techniques which measure
the response of marine organisms and ecosystems to
stress, natural and man-made.

Milestones

1. Improve capability to revisit site specific
monitoring stations with manned and unmanned
dive systems on a time series basis.

2. Improve quantitative techniques for assessing
faunal abundance - sampling and photographic
documentation (i.e. acoustic imaging, laser scaling).

II. Mission - Conduct In-Situ Studies to Understand Ecosystem
(Marine and Fresh Water) Response to Stress, Natural and Man-
Made.

A. Objective - Determine present status (geologically,
chemically and biologically) of pre-selected fishery
habitats (Great Lakes, fishing banks, basins, submarine
canyons, Long Island Sound, etc.), including designated
disposal, mining and oil/gas exploration sites.

B. Objective - Identify population and community norms
(behavioral, ecological, physiological, morphological)
that are indicative of the well-being of living marine
resources indigenous to these pre-selected habitats.

C. Objective - Conduct in-situ, site specific monitoring
of selected fauna and habitats, that are impossible to
study undisturbed, from surface vessels, in response to
disposal, mining, oil/gas exploration and habitat
enhancement (artificial reefs) activities.

263

D. Objective - Assess the fishing behavior of fixed (trap,
gillnet) and mobile (trawl, dredge) fishing gear and
assess their impact on ocean floor fauna and habitats,
including "ghost11 fishing gear. Special emphasis will be
given to the impact of mobile (dredge, trawl) gear on
inshore hard bottom (rocky) habitats, important as
nursery and juvenile habitats for lobster and other
economically valuable species.

III. Mission - Conduct In-Situ Studies to Understand the
Ecological/Environmental Factors Responsible for High
Productivity on Hard and Soft Substrates in the Gulf of
Maine. Selected Estuarine Environments and the Great Lakes

A. Objective - Determine patterns in the distribution and
abundance of benthic/epibenthic organisms.

Milestones

1. Conduct quantitative surveys, in pre-selected loca-
tions of benthic-epibenthic organisms to define
community dominance, species diversity, and
abundance in large (fishing banks, knolls, coastal
estuarine habitats) and small (ledge, boulder field,
mud patch, etc.) scale areas.

2. Relate the above to geological features, substrate
type and oceanographic/limnological conditions.

B. Objective - Define processes important to determining
the observed biotic (flora and fauna) patterns,
involving experimental manipulations and high resolu-
tion time-series monitoring.

Milestones

1. Conduct in situ experiments on the effects of
sedimentation, chemistry, and currents on biotic
patterns.

2. Conduct in situ experiments on the rate of organic
delivery to the "benthic boundary layer" versus
consumption by organisms.

3. Assess the distribution of functional groups of
organisms based on feeding types (suspension
feeders, surface deposit feeders, and macrophagous
feeders) .

4. Study in situ the interactions between organisms,
such as predation, or competition for food and
space.

5. Define "food webs" in the benthic-epibenthic
communities.

264

C. Objective - Determine the mechanisms affecting benthic-
epibenthic processes. The focus (milestones) of this
objective will be determined by the results of the above
surveys and experiments.

Milestones

1. Define energy transfer through the food web.

2 . Determine nature of environment-biota interactions and
how they effect various stages in the life cycle of
the dominant biota in the community.

IV. Mission - Conduct In Situ Studies of the Geological and
Sedimentary Features on the Ocean Floor and Great Lakes
Bottom and the Processes That Shape These Environments.

A. Objective - Assess and guantify dynamic sediment
transport mechanisms which alter habitat, including the
mechanisms of sediment erosion an deposition, and the
effects of current patterns and water masses on sediment

transport.

Milestones

1. Study in situ the effects of bioturbation (bio-
erosion) on seafloor and lake floor sediments.

2. Study in situ sediment transport mechanisms, i.e.
current patterns, water masses, and the pathways of
sediment-bound pollutants/contaminants .

3. Study in situ erosion of submarine canyon, upper slope
and shelf environments.

4 . Define distribution patterns for various sediments and
their load of trace metals.

B. Objective - Evaluate suitability of pre-selected seafloor
sites for the disposal of dredge spoils and other wastes.

Milestones

1. Apply certain key criteria for designating deep ocean
target disposal areas: avoid productive seafloor
habitat, select containment basins and chart shape and
mass balance of mound on soft-flat sediment terraine.

2. Determine mechanisms of sediment containment, chart
shape and microtopographic features of mound surface,
define peripheral limits and plot frontal boundary
change with time.

3. Determine fishery impact effects (attraction or
repulsion) at the disposal sites and long-term
recolonization trends of benthic organisms.

4. Identify and monitor key indicator species for
behavior response, and bio-accumulation burden of
contaminants (heavy metals, hydrocarbons or PCB
derivatives. ) .

265

5. Test and describe management procedures to reduce
pollutant load impacts (point disposal, sequential
coverage, capping and burrow pit) .

C. Objective - Investigate in situ the processes and
properties associated with the fluff layer and nepheloid
layer at the sediment-water interface.

Milestones

1. Implace fine-scale instrumentation (i.e. cycloidal
current meter arrays) in precise locations to
determine hydrodynamic forces producing geological
seafloor structures (i.e. furrow fields, ripple zones,
sand dunes) .

2. Quantify the mechanisms responsible for benthic flux
of biochemically active compounds (i.e. nutrients, C,
N, P) and trace metals across the benthic boundary
layer.

3. Document gradients of sediment fabric and bio-
geochemical state by sediment profile photography
(REMOTS system) and computer image analysis.

4. Determine turnover rates of surficial sediments by in
situ tracer and x-radiography experiments.

V. Mission - Provide "Ocean Services" Assistance to State,
Federal and Academic Research Institutions.

A. Objective - Support research activities designed to
establish, survey, and assess potential and existing
marine sanctuaries within the U.S. Extended Economic Zone,
including qualitative and quantitative surveys of the
biota and habitat types.

B. Objective - Calibrate, groundtruth, and evaluate remote
sensing instruments (side scan sonar, high resolution
bathymetry) .

C. Objective - Provide on-site training of marine and fresh
water scientists (including students) in the use of manned
and unmanned diving systems and their complement of
sensing, sampling, and photographic devices.

D. Objective - Conduct technical sessions with ROV research
and development engineering groups to provide biological/
oceanographic recommendations for priority tasks and
specific designs to achieve the maximum performance
potential of "low cost" ROV systems (e.g. Mini-Rover, Sea
Rover, Super Phantom) . Field test fisheries/pollution/
monitoring capabilities of a range of new generation ROV
systems currently available to support undersea research.
Continue to interact with principal submersible/ROV
contractors in the design and perfection of innovative
scientific devices to accomplish a greater range of in

266

situ tasks (i.e. parallel laser beam scaling system,
nepheloid-f luf f layer sampler, box and punch cores, cages,
electrosampler, plankton-suction sampler) .

VI . Mission - Conduct Biological and Geological Studies In-Situ
on the Environmental Mechanisms Affecting the Survival and
Growth of Selected Species Targeted for Agriculture.

A. Objective - Determine the effect of increasing east-to-
west Long Island Sound nutrient/phytoplankton and
pollution gradients on recruitment and growth of a prime
shellfish species (Mercenaria) .

B. Objective - Evaluate, by in situ methods, the
environmental influences on growth and survival of post
set clams (water quality, predation, substrate, density
dependence) at eight geographically spaced stations
throughout Long Island Sound.

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Full text of "Scientific applications of current diving technology on the U.S. continental shelf : results of a symposium sponsored by the National Undersea Research Program, University of Connecticut at Avery Point, Groton, Connecticut, May 1984 / edited by Richard A. Cooper, Andrew N. Shepard"

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