Bacterioplankton in the lower Amur River

The main microbiological characteristics of the waters of the lower Amur Ri ver are presented: the total abundance of bacterioplankton (TAB) and its bi omass, the number of aquatic fungi and bacteria belonging to certain physio logical groups, the intensities of CO2 dark assimilation (DA), methane oxid ation (MO), and organic matter decomposition (D), and also the rates of gro wth and production of bacterioplankton. Spatial and seasonal heterogeneity of bacterioplankton is shown. River water zones subjected to a heavy anthro pogenic load were revealed, where the number and physiological activity of bacteria increased 10-10(3)-fold. TAB increased to 7-8 x 10(6) cells/ml wit h the numbers of saprophytic and cellulolytic bacteria amounting to 5-6 x 1 0(3) and 2 x 10(3) cells/ml, respectively, and coli-index increasing to 250 0. The daily intensities of the processes also increased: DA-up to 15 mu g C/l, MO-up to 5 mu l CH4/l, and D-up to 0.5 mg C/l.