VANN: Long-term effects of a biological invasion

Exotic species represent an increasing global threat resulting in ecological disturbance and biodiversity loss in natural ecosystems. In spite of recent emphasis on these problems, several aspects of introductions and invasions are still poorly understood . The present project relates to a non-native fish species (vendace, Coregonus albula) that has invaded the subarctic Pasvik watercourse (Norway, Russia and Finland) after introductions into the Finnish headwaters. The project concludes a unique long-term study, following the invasion progress and impacts by annual studies over a total time span of 20 years (1991-2010). Investigations cover the developments of both the invader and the receiving community, including studies of ecological and evolutionary e ffects as well as a large-scale field experiment addressing the possibility of biocontrol by predator enhancement. Ecological impacts of the invasion involve large changes in population dynamics of the invading species, dramatic population decline of nati ve species, and major changes in food web structure and dynamics of the receiving ecosystem. The time-series facilitates an unparalleled model study of invader success and adaptations, long-term invasion impacts, management implications and the exploratio n of potential alleviation means after a biological invasion in a northern ecosystem.