Complex analysis of the plankton community of two brown-water bog lakes in the European part of Russia.
The composition and vertical distribution of plankton of two polyhumic bog lakes on the territory of the Volga-Kama State Natural Biosphere Reserve were studied. It was found that the anaerobic conditions were formed in the water column at a depth deeper than 2 m due to stratification and lack of light. Phyto- and zooplankton (including ciliates) prevailed in the upper aerobic layers of water, heterotrophic bacteria and green sulfur bacteria (Chlorobiaceae) - in the anaerobic zone. Rotifers dominated the metazooplankton in the whole water column (>95% of the biomass); prevailing genera were Asplanchna, Polyarthra, and Bipalpus. Heterotrophic organisms formed 70 ± 10% of the plankton biomass in both lakes. A high proportion of ciliates (on average 3%, maximum up to 18%) and heterotrophic bacteria (on average 49 ± 25%) was also revealed. The invasive species algae Gonyostomum semen (Raphidophyta) was first registered in the lakes of the Republic of Tatarstan. It formed 28-80% of the phytoplankton biomass in the studied lakes. It was found that at least one of the ciliate species (Frontonia cf. leucas) is able to feed on G. semen cells in situ.