marine ecological studies at palmer station and vicinity w. timm and david r. viglierchio department...

Shetland Islands, but in general the topography wasso rough that great care had to be exercised to avoidlosing the sampler.

This cruise yielded 19 samples. Half of these arefrom shallow South Shetland waters and contain arich soft-bottom fauna. Preliminary inspection of thesamples indicates that they are well suited for studiesof high-latitude emergence.

Marine Ecological Studiesat Palmer Station and Vicinity*

WILLIAM E. STOUT and STEVEN V. SHABICA

Marine Science CenterOregon State University

During the 1970 summer season, a study transectwas laid out near Palmer Station comprising 28 sta-tions from high tide level to 16 m below. At 13 sta-tions, experimental plots of 1 m 2 were cleared of plantand animal life, and the replacement and growth oforganisms are being studied on these plots throughoutthe year. Three distinct subtidal regions can be rec-ognized: (1) a gently sloping rock substrate withincreasing amounts of sediment with depth, charac-terized by the limpet Patinigera polaris, Hildenbran-dia, and other algae, and the sea urchin Sterechinusneulnayeri; (2) a relatively flat mud bottom charac-terized by the bivalve Laternula elliptica, algae, andoccasional clumps of the nemertean Lineus corruga-tus; and (3) a near-vertical rock face characterizedby brachiopods and a sponge-tubicolous polychaetecomplex in the lower reaches and limpets in theupper reaches.

Patinigera polaris occurs in concentrations of upto 123/m2 from 1-3 m below the low tide level, andless abundantly to 16 m, the limit of diving observa-tions. Approximately 500 specimens from variousdepths and habitats were collected, marked by at-taching fish tags with polyester resin to the shells,and returned to obtain monthly information regard-ing seasonal migration and the development of thealgal belt, temperature tolerance, growth and me-tabolism, nature of food, fecundity, and the effectsof ice on their position in the intertidal region.

The large infaunal bivalve Laternula elliptica oc-curs in concentrations of up to 75/m2 from 9 to 14 mbelow the low-tide level in semi-consolidated mud.

*This work was supported by grant GA-18348 from theNational Science Foundation.

The greatest densities were found in those areas hav-ing the least amount of surface cover. The sedimentat the site contained foraminiferans, cumaceans, poly-chaetes, small bivalves, gastropods, ostracods, isopods,and amphipods. No commensals were found associ-ated with the clam.

The food preferences of intertidal and subtidalpycnogonids were studied in laboratory aquaria. Theanimals were collected by bottom trawls from R/VHero and by scuba diving. Austrodecus sp. and Penta-nymphon antarcticum were found associated withsponge, Bryozoa, and hydroids. Both species preferredhydroids to Bryozoa and sponge. Colossendeis ro-busta, C. australis, and Ammothea carolinensis, thethree largest subtidal pycnogonids collected, werefound associated with brachiopods, tubicolous poly-chaetes, and encrusting red algae. Colossendeis ro-busta was observed to feed in soft sediments andC. australis preferred tubicolous polychaetes. Hedg-peth (personal communication) had suggested thatsome large Colossendeids might be feeders uponmeiobenthos in soft sediments. The food preferenceof Ammothea carolinensis was not determined. Theone specimen collected, an ovigerous male, was verysluggish and remained stationary with the proboscisresting in the mud. Colossendeis megalonyx mega-lonyx, Decolopoda australis, Pallenopsis cf. patagon-ica, and Nymphon sp. were collected by trawling inthe Port Lockroy area. Decolopoda and Pallenopsiswere observed to feed in the soft sediments. C. mega-lonyx preferred tubicolous polychaetes and Nymphonsp. preferred hydroids. Several specimens of Acheliasp. were collected in the intertidal zone at Port Lock-roy. All specimens were associated with hydroids andappeared to feed upon them.

Approximately 4,000 specimens of the small vivi-parous clam Lasaea consan guinea were collected inFebruary and March from the intertidal region atPort Lockroy and transferred to the laboratory atPalmer Station, where they are being maintained inaquaria for monthly observations on various aspectsof their reproductive biology. A study of the inter-tidal association was made. In the intertidal zone,L. consanguinea is confined to the mid-tide levelwithin a very narrow vertical range. The clams werecollected on rocks covered by hydroids and algae.Close examination revealed that the byssal threadsof the clams were not attached directly to the rocksbut rather to the hydroids and algae. The entangledmass of byssal threads, hydroids, and algae provides ahabitat for numerous organisms, e.g., turbellarians,gastropods, polychaetes, amphipods, copepods, ostra-cods, nematodes, and pycnogonids. Turbellarians andamphipods were the most conspicuous members ofthis association. Many of the clams had epizoic folli-culinids on them. From a total population of 895

134 ANTARCTIC JOURNAL

clams collected in February, a sample of 76 was ex-amined. Of these 76, 39 bore young. The largestyoung measured while still in the parent ranged from0.15 to 0.40 mm. Generally, it was found that thelarger individuals tended to produce more youngthan the smaller ones. The size of the smallest indi-viduals brooding young is not known, but no youngwere found in clams 2.5 mm in length or smaller. Inaddition, in the larger specimens, there were clamshaving no young; however, these clams may havebeen dead, since the valves were reflexed. The meannumber of young brooded per specimen ranged fromzero to 75.2. The greatest number of young broodedby a single adult was 132. The stomach contents ofmany specimens were examined and consisted ofdetritus.

Studies of Antarctic Nematodes

RICHARD W. TIMM and DAVID R. VIGLIERCHIO

Department of NematologyUniversity of California, Davis

This study, carried out during the 1969-1970 sea-son, consisted of two parts—one concerned withtaxonomy and the other with physiology. Nematodesof the Antarctic have not been well studied. The col-lections obtained by the early expeditions, around theturn of the century, and the resulting specimen de-scriptions were less than satisfactory for taxonomicpurposes. To confirm these earlier findings, to im-prove the old descriptions, and to add new informa-tion, nematodes were collected over a wide area ofRoss Island and the coast of Victoria Land. Six spe-cies of soil and freshwater nematodes were obtained,including one new genus and two new species.Dredging for marine nematodes was carried outthrough ice holes near McMurdo Station and ScottBase at six different depths and from the icebreakerUSCGC Burton Island off Cape Royds at two dif-ferent depths. So far, 190 species of marine nema-todes, including two new genera, have been mountedon slides.

The other part of the project concerned theosmoregulatory mechanisms of free-living nematodes,i.e., their ability to take up or release cations oranions. Several large marine nematodes reportedfrom McMurdo Sound are especially suitable forsuch physiological studies because they can be easilyhandled and measured. Experiments were carried outon freshly collected live animals to assess their re-sponses to hypertonic and hypotonic solutions. These

determinations were made directly on two large ma-rine nematodes with the aid of an ocular micrometerin a dissecting microscope. With this experience asbackground, the experimentation was expanded toinclude a small free-living marine nematode and afree-living soil-inhabiting form. The responses wererecorded photographically. Nematodes regulating incertain hypo- and hypertonic solutions were selected,freeze-dried, and returned to the Department ofNematology, University of California, Davis for ionanalysis.

Limnological Investigationsof Algal Communities

BRUCE C. PARKER and GENE SAMSEL

Department of BiologyVirginia Polytechnic Institute

During the austral summer of 1969-1970, we stud-ied a series of meltwater ponds in the vicinity ofAnvers Island, off the western coast of the AntarcticPeninsula, making field trips by boat from PalmerStation to nearby islands and peninsulas. Our studieswere aimed at understanding biological conditions inantarctic fresh waters. We conducted a preliminarylimnological survey of six lakes and meltwater pools,two of the larger and more contrasting of which werelocated on Humble Island ("Humble Island Lake")and behind the old British station at Norsel Point("Skua Lake"), respectively. Environmental param-eters such as light, temperature, pH, nutrients, chlo-rophyll, photosynthetic rates of phytoplankton popu-lations (by the in situ C 4 method), etc. were meas-ured, and algae were collected for identification.

"Skua Lake" and "Humble Island Lake" possessstrikingly different trophic levels, there being no over-lap in their diurnal rates of C 14 uptake. Both pondsderive input meltwater from glacial ice and snowdrifts, with their output channeled toward ArthurHarbor. Located only one-quarter mile apart, theywere both partially ice-covered during the entire sea-son. Both lakes were underlain by a quartz-rich dio-rite containing small amounts of biotite and muchNa plagioclase.

With the exception of Cl, NH 3–N, and totalPO4 , nutrient concentrations in oligiotrophic"Skua Lake" were similar to those found in eutrophic"Humble Island Lake." Concentrations of Cl-,NH3–N, and PO 4 E in "Humble Island Lake" weremany times those in "Skua Lake." Total chlorophyll

July–August 1970 135