BACTERIA IN THE SEA-ICE ZONE BETWEEN ELEPHANT-ISLAND AND THE SOUTH-ORKNEYS DURING THE POLISH SEA-ICE ZONE EXPEDITION, (DECEMBER 1988 TO JANUARY 1989)

During austral summer 1988/89, total bacterial Acridine Orange Direct Counts (AODC) in seawater, mean 6.0 x 1O(6) l-1, were three to ten tim es lower than generally reported for the Bransfield Strait to north We ddell Sea area. In contrast, numbers of viable bacteria (Colony Formin g Units, CFU), mean 10.6 x 10(3) l-1, were two to three times higher t han reported. Bacterial abundance here shows large seasonal and spatia l changes. On the basis of bacterial, diatom, detritus, and amino acid data from this study, two main regions were defined: 'Cold winter wat er' in the west with high salinity and low CFU, AODC, and other parame ters. In the east, lower salinity and higher values for all parameters were found in warmer meltwater at the surface. CFU and AODC values in ice were respectively six and 85 times higher than in surrounding sea water. Taxonomic studies indicate considerable diversity in genera and nutritional requirements of isolated bacteria. Sea-ice and water colu mn bacterial communities differed. Many isolated strains, however, wer e found in both habitats. Sea-ice seems to be important in regulating surrounding bacterioplankton.