Current state and forecast of changing hydrobiont communities in the construction zone of the Nizhny Novgorod low-pressure hydrounit

The authors of the paper think that it is necessary to study the structural and functional changes of hydrobiocenoses in case of river runoff regulation and new reservoir creation to make competent, ecologically correct management decisions. The widespread use of the analogy method for the ecological forecasts of reservoirs state is shown. At the present time, the issue of diagnostics of ecological systems which falls into the zone of impact of the planned construction of the Nizhny Novgorod low-pressure hydrounit (NNPG) in the river hydraulics zone of the Cheboksary water reservoir has been actualized. The authors characterize the current state of the species structure of phyto-, zooplanktonocenosis and zoobenthocoenoses of this zone, including species richness, the ratio of quantitative indicators of the main systematic groups and dominant species. The paper shows hydrobiocenoses formation sources and types of anthropogenic impact on them. The authors forecast changes in the structural and functional characteristics of the communities of hydrobionts of the «Sormovsky» reservoir, taking into account the expected ecological situation after the construction of the Nizhny Novgorod low-pressure hydrounit, including the main limiting factors. As an analogue of a new reservoir, the Cheboksary reservoir in the first years of its existence was chosen. The possibility of spreading new invasive species (Kellicottia bostoniensis (Rousselet, 1908), Diaphanosoma orghidani (Negrea, 1982) and Gmelinoides fasciatus (Stebbing, 1899)) is considered in the paper. In conclusion the authors suggest permanent monitoring of the new reservoir.