Phytoplankton of the lake Palanskoye: taxonomy, ecology, dynamics of quantitative characteristics
The plankton algae community of Palanskoye Lake consists of plankton cosmopolitan, cold-water, typically freshwater, alkali-prefer species. Among species able to indicate organic pollution the species of naturally pure waters predominate. Only a small group in the pool of 80 species identified in plankton is structure-forming. The species contributing maximally to the abundance are diatom <i>Aulacoseira subarctica </i>(42<i>%</i>) and blue-green algae (31<i>%</i>) of <i>Microcystis </i>genera. The main part in the phytoplankton biomass (59<i>%</i>) consists of <i>Aulacoseira subarctica. </i>The species to contribute to the biomass less are <i>Tabellaria flocculosa</i>, <i>Stephanodiscus alpinus</i>, <i>Asterionella formosa</i>, <i>Cyclotella tripartita, Synedra ulna, Synedra </i>cf. <i>actinastroides </i>and <i>Diatoma elongatum</i>. The part of <i>Microcystis </i>is miserable. The intraseasonal dynamics of the total abundance of phytoplankton typically demonstrates a consequent increase of the abundance from June to September suddenly changing into decrease in October. Although there is no observed a clear answer of phytoplankton biomass to the income of phosphorous from fish carcasses or mineral fertilizers, the long-term dynamics of phytoplankton abundance and biomass exhibits the tendency of growth since the second half of the 1990<sup>th</sup> to 2001-2005, which probably can be reckoned as an effect of the phosphorous accumulation in this lake system.