Abundance, Biomass and Production of Heterotrophic Bacteria in a Large Plain Reservoir During the Ice-Covered Period
D. B. KOSOLAPOV, A. I. KOPYLOV
Papanin Institute for Biology of Inland Waters, RAS, 152742, Borok, Nekouz, Yaroslavl
Keywords: гетеротрофные бактерии, планктонное сообщество, период ледостава, крупное равнинное водохранилище, heterotrophic bacteria, plankton community, ice-covered period, large plain reservoir
Abstract
Abundance, biomass, production and size-morphological structure of heterotrophic bacteria were determined and their contribution to the total plankton biomass was evaluated in the Rybinsk reservoir (the Upper Volga) during the ice-covered period. Structural and functional characteristics of bacteria, except for their cell sizes in winter were lower than those in the growing season. However, heterotrophic bacteria contributed mainly (89.3 %) to the total biomass of plankton community in winter. During the growing season phytoplankton was a major component of the plankton (48.8 %), while the bacteria averaged 36.5 %. The total plankton biomass under the ice averaged 148 mg C/m3 that was 2.6 times lower than in the period of open water. During the ice-covered period the number of protists was small and they consumed an insignificant part of the bacterial production, and the viral lysis was the main reason of the bacterial mortality.
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