Rybinsk reservoir

SPECIFIC COMPOSITION AND ABUNDANCE OF THE WINTER ZOOPLANKTON IN THE RYBINSK RESERVOIR

Authors: Lazareva V. I., Sokolova E. A.

The specific composition, seasonal dynamics, vertical and horizontal zooplankton distribution were studied in the pelagic zone and littoral of the Rybinsk reservoir in the winters of 2008 – 2016. The zooplankton abundance was found to be low (the abundance < 10,000 ind./m3, the biomass < 0.1 g/m3), by an order of magnitude lower than the values recorded in the 1970 – 1980s. As earlier, the abundance peak was observed in March. The cryophilic Cyclops kolensis prevailed among the crustaceans. A reproducing population of C.

VIRAL INFECTION OF PICOCYANOBACTERIAE IN THE RYBINSK RESERVOIR DURING THE FREEZE-UP PERIOD

Authors: Kopylov A. I., Kosolapov D. B., Zabotkina E. A.

The virioplankton and planktonic picocyanobacteria abundances in the deep and shallow waters of the Rybinsk reservoir during the freeze-up period (the water temperature within 0.3 - 0.9°C) varied within (37.1 - 84.1)×106 ((57.3±2.1)×106 on the average) particles/ml and (13.5 - 75.0)×103 ((48.7±3.4)×103 on the average) cells/ml, respectively. The fraction of picocyanobacteria with viruses attached to their cell surface was 6.5 - 29.0% (12.0±0.8% on the average). The proportion of visible infected cells was 0.7 - 7.6% (2.2±0.3% on the average) of the numbers of picocyanobacteriae.