Morphology and ecology of bivalve molluscs from Admiralty Bay, King GeorgeIsland, Antarctica

Bivalve species were collected from shallow coastal areas of King George Is land (Martel, Mackellar and Ezcurra inlets of Amiralty Bay). Twenty one spe cies belonging to 16 genera and 12 families were identified and their morph ometric and morphological shell characteristics were described. Three main characteristics were found to be common to the majority of the bivalve spec ies sampled: 1) thin fragile shells; 2) small size of individuals (76%), an d 3) the lack of true cardinal teeth (72%). Comparison of calcium data from a tropical estuary and a subantarctic coastal shallow area suggested that the calcium in the sea water was not a constraint to shell building but she ll thickness could be an adaptation to the efficiency of energy partitionin g. Small individual size and the lack of true cardinal teeth are discussed in relation to a high deposition environment and widespread mud bottoms.