EVIDENCE FOR A MARINE MOLLUSCAN FAUNA BENEATH ICE SHELVES IN THE LAZAREV AND WEDDELL SEAS, ANTARCTICA, FROM SHELLS OF ADAMUSSIUM-COLBECKI AND NACELLA (PATINIGERA) CF CONCINNA

Only one living specimen of Adamussium colbecki was found amongst the shells of this species collected in the Lazarev and Weddell Seas, and those of the limpet Nacella cf. concinna from three locations in the s outhern Weddell Sea. In order to explain this peculiarity four hypothe ses are discussed. The possibility that the shells belong to living de ep-water populations is in contradiction to the high number of trawl s amples taken in the area and the abundance of empty shell material. C- 14 dates show the shells are recent, thus excluding the possibility th at the shells belong to autochthonous fossil populations exposed on th e seafloor. Lateral transport of living specimens or shells overlong d istances by marine currents or by ice is unlikely due to their state o f preservation and the water circulation pattern. The most likely expl anation is that the shells are allochthonous, transported only over sh ort distances by marine currents from adjacent areas underneath floati ng ice shelves where both species have living populations.