Features of the Spatial Distribution of Invasive Amphipod Species in the Littoral of Lake Ladoga

The modern distribution of invasive amphipods of Baikal (Gmelinoides fasciatus (Stebbing, 1899), Micruropus possolskii Sowinsky, 1915) and Ponto-Caspian origin (Pontogammarus robustoides Sars, 1894, Chelicorophium curvispinum (Sars, 1895)) in Lake Ladoga is described. The heterogeneity of the distribution of quantitative indicators of amphipods in different parts of the lake was established. The most widespread species in the littoral zone was G. fasciatus. A decrease in the contribution of G. fasciatus in the bottom communities of macrozoobenthos was noted. The dominant role of G. fasciatus was observed only in those parts of the lake where other species of invasive amphipods were not established yet. The range of Ponto-Caspian amphipods is limited by the boundaries of the Volkhov Bay. A significant increase in the quantitative development of P. robustoides and active southward spread of M. possolskii along the west coast of the lake indicate the ongoing restructuring of littoral biocenoses.