square meter). The level of the extreme low tide was the only Kerguelen. Introduction écologique. (Comité National francais des Re- portion of the transect which had no bare rock surface. The cherches Antarctiques), 30, 1-66. Guille, A. 1977. Benthic bionomy of the continental shelf of the Ker- , lateralis, was found on exposed rock sur- faces from low tide to extreme high tide. Although these guelen Islands: Quantitative data on the echinoderms of the Mor- bihan Gulf. In Adaptations within antarctic ecosystems, Houston: Gulf may remain in certain locations for extended periods of time, Publishing Company. field experiments indicate that individuals may move considera- Lawrence, J. M., and A. Guille. 1982a. Numerical and caloric densities ble distances during a period of immersion. of ophiuroids and holothuroids (Echinodermata) form Kerguelen This research was supported by National Science Foundation (South Indian Ocean) and Banyuls (Mediterranean Sea). In J . M. grant DPP 82-12702 and by Territoires Australes et Antarctique Lawrence (Ed.), Echinoderms, Proceedings of the International Conference, Françaises. Tampa Bay. Rotterdam: A. A. Balkema. Lawrence, J. M., and A. Guille. 1982b. Organic composition of tropical, polar and temperate-water echinoderms. Com narative Biochemistry and Physiology, 7213, 283-287. References Strathmann, R. R., and M. F. Strathmann. 1982. The relationship be- tween adult size and brooding in marine invertebrates. American Arnaud, P. 1974. Contribution a la bionomie marine benthique des Naturalist, 119, 91-101. regions antarctiques et subantartiques. Tethys, 6, 465-656. Thorson, C. 1950. Reproductive and larval ecology of marine bottom Bellido, A. 1982. Les biocenoses du littorale rocheux aux iles Kerguelen. invertebrates. Biological Reviews, 25, 1-45. 51, 81-91. Comité National francais des Recherches Antarctiques, Turner, R. L., and J . H. Dearborn. 1979. Organic and inorganic com- Delephine, R. 1963. Un aspect des etudes de biologie marine dans les position of post-metamorphic growth stages of Ophionotus hexactis isles australes françaises. Comité National francais des Recherches Ant- (E. A. Smith) (Echinodermata: Ophiuroidea). Journal of Experimental arctiques, 3, 1-22. Marine Biology and Ecology, 36, 41-51. Chia, F S. 1974. Classification and adaptive significance of develop- Turner, R. L., and J. C. Rutherford. 1976. Organic, inorganic, and calor- mental patterns in marine invertebrates. Thalassia Jugoslavica, 10, ic composition of eggs, pentaculae, and adults of the brooding sea 121-130. cucumber Cucumaria curata Cowles (Echinodermata, Holothuroidea). Grua, P. 1971. Invertébrés de linfralittoral rocheux clans larchipel de Journal of Experimental Marine Biology and Ecology, 24, 49-60.

Echinoderm studies along the Antarctic Peninsula

JOHN H. DEARBORN, KELLY C. EDWARDS, DAVID B. FRATT, and WILLIAM E. ZAMER

Department of Zoology University of Maine at Orono I Orono, Maine 04469

During Wv Hero cruise 83-3, 25 February to 22 April 1983, University of Maine personnel K. Edwards, D. Fratt, and W. Zamer conducted field work along the Antarctic Peninsula as part of a study to clarify the trophic position of selected as- teroids and ophiuroids (sea stars and brittle stars) within the antarctic marine ecosystem. Several approaches have been used to address this problem, including detailed analyses of stomach contents, observation of feeding behaviors under laboratory conditions, and scanning electron microscope (sEM) studies of the morphology of feeding structures. Underwater photogra- phy with a Benthos (Benthos, Inc., North Falmouth, Mas- sachusetts 02556) model 371 underwater camera and model 381 underwater flash was used to observe asterozoans under natu- ral conditions. During this final field season, emphasis was placed on the collection of several asterozoan not pre- A euryalld brittle star Astrotoma agassizii (disc diameter 45 milli- viously found in sufficient numbers for reliable diet analysis. meters) clinging to the stand pipe in a laboratory holding tank at These included the asteroid Granaster nutrix and ophiuroids Palmer Station. This species uses its flexible arms to capture small Astrotoma agassizi (figure), Ophiosparte gigas, and Ophiurolepis zooplankton, primarily copepods. (Photo taken 15 March 1983 by ge/ida. Kelly C. Edwards.)

1983 REVIEW 193 Sampling localities ranged from the Argentine Islands in the made by hand or by traps set from zodiacs. One particular south, to the Bransfield Strait and Hope Bay (Bahia Esperanza) objective of this local work was the collection of the shallow- in the north. A total of 17 trawl stations were made at depths subtidal sea star Granaster nutrix. This little-known asteroid is ranging from 30 to 676 meters. At three of these stations, intact abundant on rocky substrates throughout Arthur Harbor, but sediment samples were obtained with a grab sampler. Analysis can be extremely difficult to collect because of its habit of wedg- of this sediment will provide information on bacterial and meio- ing itself into crevices and under rocks. Previous attempts at faunal abundance and on the composition of the diatom flora. dip-netting this sea star from zodiacs have met with little suc- Comparisons of environmental sediment with sediment from cess. This season a sufficient number of specimens was ob- stomachs of organisms taken at the same sites will help to tained by wading and SCUBA for reliable analysis of gut contents determine the diets of a number of deposit-feeding and morphological variation. echinoderms. We succeeded in measuring two fundamental physiological Eight camera stations were made at depths ranging from 52 to parameters of Granaster nutrix in the Palmer Station laboratory. 676 meters. A total of 15 rolls of film was used. These pho- Oxygen uptake rates were determined by Winkler titration on tographic data provide information on the distribution, orienta- that had been maintained at -0.50C ± 0.5 0, 34.5 % tion, and associations of echinoderms and other salinity and starved for 10 days. In two separate experiments 13 macroinvertebrates. animals of the available size range (0.20-0.94 grams whole ani- A total of 153 whole or dissected specimens of asteroids and mal wet weight) were used to determine the metabolism-size ophiuroids was taken for morphological study with SEM. Two relationship for this . Values of oxygen uptake ranged fixatives were used in processing these samples. Some spec- from 11 to 64 microliters per gram per hour. The equation imens were fixed in a phosphate buffered solution of 4 percent relating the logarithm of oxygen uptake (y) to the logarithm of formalin, 1 percent glutaraldehyde. Others were fixed in 2 whole animal weight (X) is y -0.9298X + 1.0898; r2 = 0.509. percent glutaraldehyde in 77 percent seawater. All specimens Ammonia excretion rates were measured using a spec- were retained in the fixative solutions for transport and subse- trophotometric method. Nine animals were incubated for 90 quent storage. minutes in 25 milliliters of sea water (34.5 %o salinity) main- At each trawl station, extensive collections of echinoderms tained at -0.5°C ± 0.5°; all animals were starved for 10 days. were preserved for later analysis of stomach contents. Some Ammonia excretion rates were 8.7-57.0 nanomoles per gram large asteroids such as Pilaster charcoti, Bat hybiaster loripes obesus, per hour. (Whole animal wet weight range was 0.38-0.94 and Diplasterias brucei were measured, sexed, and dissected grams.) From the oxygen uptake data and these ammonia excre- aboard ship. Stomach fullness was noted and gut contents pre- tion rates, oxygen-to-nitrogen atomic ratios have been calcu- served for complete analysis in Maine. Smaller asterozoans lated. Data were also obtained on the proximate biochemical were preserved whole. Representative collections of selected composition and ash content for this unusual asteroid. invertebrates were also preserved from most localities as part of We are indebted to Capt. Pieter J. Lenie and the crew of the a cooperative program with the Smithsonian Oceanographic RIv Hero for excellent field assistance and to personnel at Palmer Sorting Center. Station for laboratory support. Pat Mosier and Mark Olson In addition to the work conducted aboard IIv Hero, numerous carried out the SCUBA operations. This work was supported by shallow-water collections in the vicinity of Palmer Station were National Science Foundation grant DPP 79-21537.

Superswarms of antarctic krill krill swarm near Elephant Island, just off the tip of the Palmer Peninsula (figure 2). We located the swarm initially due to the (Euphausia superba Dana) presence of a very large Soviet trawler fleet which was harvest- ing the krill (we observed over 40 trawlers at one time, by unaided eye, from the Melvilles bridge). We located and map- ERIC SHULENBERGER ped the patch acoustically (Macaulay, Antarctic Journal, this is- sue): it was several kilometers wide in both horizontal dimen- San Diego Natural History Museum sions, up to several hundreds of meters thick, performed no San Diego, California 92112 diurnal vertical migration, and had no surface manifestation. The krill patch was nearshore, occurring near "shelf breaks" (figures 2 and 3). It had very sharp lateral and upper boundaries In February-March 1981 over 20 U.S. scientists participated (figure 3), and was persistent and mobile. We adopted the term in cruise Vulcan leg 7 (R/v Melville, Scripps Institution of "superswarm" to describe the phenomenon. Macaulays acous- Oceanography) to the Scotia Sea (figure 1). We originally in- tic estimates gave a total krill biomass for this superswarm of tended to do a statistical investigation of the open-sea patches of about 2-10 million tons: up to 10,000 animals (10 kilograms per krill (Euphausia superba Dana) which are well known in the cubic meter. If accurate, this is the largest collection of one popular literature, but about which there is disconcertingly species of animal tissue ever discovered on Earth. This super- little detailed information. We found no "ordinary" krill swarms swarm phenomenon had basically not been documented or but received reports (from the German R/V Meteor) of a massive reported before.

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