Amphipods (Crustacea: Amphipoda) of Lake Ladoga

Abstract

Surveys conducted between 2019 and 2023 identified six out of the eight known amphipod species in Lake Ladoga, including two native (Monoporeia affinis and Pallaseopsis quadrispinosa) and four invasive taxa (Gmelinoides fasciatus, Micruropus possolskii, Pontogammarus robustoides, and Chelicorophium curvispinum). Two additional species (Gammaracanthus lacustris and Gammarus lacustris) remain rare in the lake and were not recorded in our samples during the study period. Spatial analysis highlighted distinct distribution patterns: native relict amphipods exhibited lower abundance in northern deep-water areas compared to southern regions, while invasive species dominated the littoral zone in terms of biomass. Monoporeia affinis reached densities of up to 21.26 g/m² in open waters, whereas Gmelinoides fasciatus prevailed in littoral habitats (31.32 g/m²). The Ponto-Caspian invaders Pontogammarus robustoides and Chelicorophium curvispinum remained restricted to Volkhov Bay, though C. curvispinum expanded its range within the bay. Notably, Micruropus possolskii demonstrated active northward and southward dispersal, with maximum biomass recorded along the western coast and Petrokrepost Bay (18.39 g/m²). These findings suggest that M. possolskii is likely to colonize the entire littoral zone of Lake Ladoga — Europe’s largest lake — and potentially spread to connected water bodies.