Abundance and biomass of bacterioplankton in waters of the Kara Sea and the Ob and Yenisey Rivers

Bacterial cell number in the water column of the Kara Sea and estuary areas of the Ob and Yenisey Rivers was determined in water samples collected at 32 stations at depths from the surface to 200 m. The samples were analyzed by direct microscopy. In most parts of the sea microorganism concentrations ranged generally from 103 to 104 cells per ml and their biomasses from milligrams to tens of mg/m**3. Bacterioplankton concentration of river waters was much higher than in the open sea, especially in Ob waters. The highest bacteria concentrations, hundreds of thousands cells per ml with biomass exceeding 200 mg/m**3, were found in the southern part of the Ob section. Minimal concentrations were observed in the northeastern part and near the southeastern part of the Ob section and the southeastern coast of Novaya Zemlya. Dark CO2 fixation rates determined at some stations indicated low bacteria biomass production

Bacterial methane oxidation rates in waters and sediments of the Kara Sea and the Yenisey River estuary

Abundance of methane oxidizing bacteria and CH4 oxidation rates were studied in water and sediments of the Yenisey estuary, the Bay of Yenisey, and the adjacent region of the Kara Sea. Number of methanotrophs reached 7900 cells/ml. CH4 oxidation rate in water was 0.4-200 nl/l/day and in 1 kg of sediments it was 4-3300 nl of CH4 per day. Maximal rates of this process were recorded in water and bottom sediments of the river part of the section and minimal rates were recorded in the marine part of the section