Department of Antarctic Biology, Polish Academy of Sciences
Abstract
Bacterial numbers at standard depths (10/50, 100, 200, 300, and 400 m) in Admiralty Bay, King George Island, South Shetland Islands, were determined from April 1990 to January 1991. Neither CPU (Colony Forming Units on nutrient media, ca. 10^3/l), nor total bacteria (AODC-Acridine Orange Direct Count, ca. 10^7/l) numbers varied significantly over the 400 m water column; temporal variation was low, and means and ranges decreased with depth. Significantly more CPU were isolated from 100 m and 200 m after incubation at 15℃ than 1℃ (p<0.05). Close inshore in Half Moon Cove, bacterial numbers at 5 and 10 m depth were similar to those at the bay\u27s centre; significantly more CPU were also isolated here after incubation at 15℃. Mean cell volume and biomass in the upper 100 m was 0.228 μm^3 (n=1636), and 50.63 fg C/cell respectively. Bacterial carbon in the upper 100 m (mean 3.415 μg C/l) ranged widely (August, 0.338 μg/l; January, 37.321 μg/l). Rods dominated the total bacteria in most samples. Values of a number of these parameters to levels below those usually reported here during offshore summer cruises, underline the importance of long-term inshore bacteriological studies in the Southern Ocean, particularly over the austral winter