Table 3: Comparison of freshwater species in Ob and Yenisei during the 1997 cruise@en

Phytoplankton biomass distribution (chlorophyll a, chl. a) and species composition (cell numbers) were investigated during three expeditions to the Kara Sea with \"Akademik Boris Petrov\" (BP) in 1997, 1999, and 2000. The distribution of biomass in the estuaries of Ob and Yenisei showed a similar range in 1997 (0.2 to 3.2 µg/l) and 2000 (0.4 to 3.5 ug/l); higher chl. a concentrations during these two years were found in Yenisei than in Ob. In 1999, phytoplankton biomass in the Ob and Ob Estuary was much higher than in 1997 and 2000, with maximum values above 10.0 ug chl. a/l. In 1999, biomass in Yenisei was lower (1.5 to ~5 ug/l) than in Ob but slightly higher than in 1997 and in 2000. During the expedition in 2000, the research area extended farther to the north, here, lowest phytoplankton biomass during all three years was found. Typical summer values for integrated chl.a biomass (surface to bottom) ranged between 6 and 20 mg m**-2. […]