Ecological impacts of biological invasions

The invasion of vendace (Coregonus albula) to the Pasvik watercourse in northern Norway after introductions in the Finnish headwaters represents a well-documented example. The ecological impacts of this alien species have been followed by annual investigations since 1991.

The vendace is an efficient zooplankton predator and the invasion has had extensive effects on biological diversity, community structure and population and food web dynamics and in the watercourse. The impacts are related to strong ecological interactions, in particular competition and predation, which are addressed by long-term investigations of the fish and zooplankton communities.

The studies emphasis the population ecology and life history of the vendace during invasion and establishment, competitive interactions between vendace and whitefish, predation impacts on the zooplankton community and piscivore predation by brown trout on vendace and whitefish. Impacts on other fish species like perch and pike are also studied, and potential management efforts in terms of increased stockings of brown trout are evaluated.

Studies are carried out both in the Norwegian, Finnish and Russian parts of the watercourse and our research activities include comprehensive cooperation with Russian and Finnish scientists.