Benthic megafauna of the nearshore zone of Martel Inlet (King George Island, South Shetland Islands, Antarctica): Depth zonation and underwater observations

The benthic megafauna from the soft bottoms of the shallow coastal zone of Martel Inlet (Admiralty Bay, King George Island, South Shetland Islands, An tarctica) was studied during three austral summers (1989/1990, 1990/1991 an d 1994/1995) in relation to the bathymetric features. Surveying and samplin g, based on specimen counting and underwater observations, were undertaken by scuba-diving at depths down to 25 m. The depth zonation appears to be in fluenced by the nature of the substrate and especially by the action of the ice. The multiple action of ice flows prevents the occurrence of sessile f orms in the shallower areas, where a low-diversity community, dominated by motile animals, was found. In the area around Is m in depth, the action of icebergs generated faunistic and sedimentary patches of impacted and non-im pacted areas. The more stable conditions prevailing below depths of 20-25 m allowed the establishment of a more diversified epifauna, including many s essile forms. The interannual differences observed in the densities of the mobile isopod Serolis polita may be associated with the summer period when the sampling was undertaken.