SOME OBSERVATIONS ON THE DIET AND DISTRIBUTION OF NUDIBRANCHS AT SIGNY ISLAND, ANTARCTICA

Observations were made on the diet and distribution of eight species o f nudibranchs found in Borge Bay, Signy Island, Antarctica. Specimens from seven sites were examined in situ on four separate occasions duri ng 1992 and 1993 using SCUBA. A small collection for identification wa s also made. Six of the eight species present were identified, and the first ecological data for at least one species (Charcotia granulosa) were recorded. Notaeolidia gigas was feeding principally on hydroids o f the genus Tubularia over the entire depth range surveyed (3-36 m), a nd was most abundant in shallow water, whereas Tritoniella belli was o nly found at deeper sites, mostly on an octocoral of the genus Ascolep is. Charcotia granulosa and Pseudotritonia gracilidens appeared to be specialist bryozoan feeders and, as has been found at other locations, Austrodoris kerguelenesis specialised on the demosponge Dendrilla ant arctica. Two unidentified aeolid species occurred almost entirely on p articular hydroids and the prey of Tritonia antarctica was not apparen t. The physical size of Antarctic nudibranchs may have important impli cations to the type of prey and feeding strategy used by different spe cies.