The authors consider the long-term succession of phytoplankton of the middle reach of the trans border Irtysh River (Russia, Omsk) for 1998–2016. The abundance and biomass of the phytoplankton remained at the same level in the 2014–2015. Statistically significant changes established in the structure of phytoplankton: the increase of Euglenophyta in the total abundance and biomass of the phytoplankton in the relative proportion in the spring time, and the decline of Chlorophyta in the total number of phytoplankton in the relative proportion in spring and summer times. The composition of phytoplankton has identified by 88 new specific and infraspecific taxa, where are dominated Chlorophyta (31) and Euglenophyta (21). Taxonomic structure and abundance of species of the phytoplankton remained at the level of 1998–2003, that corresponds to the ecological modulation state. Qualitative changes in the species composition of the phytoplankton have negative character traits and collectively point to strengthening the eutrophication process and the pollution increase of the river water with organic matter.
Full text: PDF (Rus) 211K