Volume, abundance and biomass of sediment bacteria in the eastern mid Adriatic Sea

Bacterial abundance, biomass, cell volume, and morphological diversity were studied in sediment samples collected from the coastal area of the eastern mid Adriatic Sea. Samples from the topmost 10 cm of sediment were taken monthly from January to December 2002. The number of bacteria varied from 3.54 x 109 cells g–1 in July to 8.08 x 109 cells g–1 in September. Biomass was lowest in May (78 μg C g-1) and highest in December (378 μg C g-1). The volume of the bacteria varied markedly with season, fluctuating from 3.87 x 108 μm3 g-1 in May to 3.12 x 109 μm3 g-1 in December. Cells with a volume smaller than 0.1 μm3 accounted for the largest number of bacteria (62%) and cocci comprised 93% of these cells. More than 80% of all rod cells had a volume smaller than 0.5 μm3. The majority of filamentous cells (63%) belonged to the 0.32 μm3 volume class. Rodshaped cells were dominant in terms of volume (45-72%) and biomass (42-72%) and cocci in terms of abundance (52-70%). Cells smaller than 0.5 μm3 made up 88-94% of the bacteria and 68-84% of the biomass in the summer and 6-44% of the bacteria and and 21-81% biomass in the winter.