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International Journal of Ecology
Volume 2012 (2012), Article ID 813016, 10 pages
Research Article

Specific Niche Characteristics Facilitate the Invasion of an Alien Fish Invader in Boreal Streams

1Finnish Game and Fisheries Research Institute, Manamansalontie 90, 88300 Paltamo, Finland
2Biodiversity Change Group, Ecosystem Change Unit, Natural Environment Centre, Finnish Environment Institute, University of Oulu, P.O. Box 413, FI-90014, Finland
3Department of Biology, University of Oulu, P.O. Box 3000, 90014 Oulu, Finland

Received 4 August 2011; Revised 17 November 2011; Accepted 19 November 2011

Academic Editor: Andrew Sih

Copyright © 2012 Kai Korsu et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


We studied the ecological niche relations of native stream fish and an alien invader, brook trout (Salvelinus fontinalis), to examine if brook trout had located an underused environmental niche in our boreal study system. In both study years (1994 versus 2004), we found brook trout to have the most marginal niche position of all the fish species examined. The most important environmental variable affecting the distribution of brook trout was pH, with acid headwater sites being dominated by this species. Brown trout, in contrast, had relatively nonmarginal niche, occurring in average conditions across the sampled sites. Other fish species had niche positions between the two salmonids. Our results show that fish invasions may be strongly facilitated by the presence of suboptimally occupied environmental niche space in the recipient river system.