Modern Data on the Spatial Distribution of the Baikal Amphipods in the Yenisei River and Their Visualization in the Geoinformational Web System

The results of hydrobiological studies of expeditions conducted in 2015–2016 in several zones of the Yenisei River from its head to the mouth are presented. This work deals with the spatial dynamics of the amphipod community, in which the leading positions are occupied by invaders from Baikal. The invaders spread through the Angara River not only with the current but also against the current of the Yenisei. Eight species of amphipods were identified, and there were two representatives of native fauna (Pontoporeia affinis and Gammarus sp.) and six Baikal endemics among them. Throughout the river, Gmelinoides fasciatus dominated quantitatively among the gammarids; Philolimnogammarus viridis took second place. Only in the lower reaches and in the delta of the Yenisei were the leading positions surrendered to Pontoporeia affinis—a representative of the estuary-relic complex of organisms. Baikal endemics populated actively the Upper Yenisei section below the Sayano-Shushensky hydroelectric power station (HPS), especially in the areas of massive macrophyte distribution. The main vector of Baikal endemics spreading in the Yenisei is self-colonization through the Angara River, noticed by researchers in the 19th century. For G. fasciatus, its intentional introduction into the Krasnoyarsk Reservoir in the late 1960s with the aim of increasing the food supply was an additional stimulus for the growth of the population below and above the Krasnoyarsk HPS. Naturalization of Ph. viridis in the Upper Yenisei section was probably aided by an accidental introduction. There is a divergence of ecological niches in G. fasciatus and Ph. viridis in the Yenisei: the dominant prefers silty sand-and-shingle biotopes with a calm rate of speed; the subdominant tends to prefer stony-pebble bottom washed by a rapid current. Over the last 15 years, the density and proportion of crustaceans in the zoobenthos have increased in the Angara–Podkamennaya Tunguska section. The results of hydrobiological studies have been designed in the form a geospatial database in a geoportal, which makes it possible to visualize information as interactive thematic maps and which provides the direct access to data via web mapping services from the modern GIS software.