Impacts of Invading Centrarchids on Native Top Predators and Their Prey

The range limits of many fish species, including centrarchids, are shifting north with changes in climate. Species introductions related to shifting species distributions are expected to produce novel species assemblages and may significantly alter species interactions and lake community composition.  With future changes in climate, centrarchid introductions are expected to threaten thousands of cyprinid populations within Ontario.  It has been shown that centrarchid introductions can unevenly impact top predators in lakes with and without pelagic prey fish.  We used historical and contemporary data on fish species occurrences in Ontario lakes to examine the impacts of centrarchid introductions.  While controlling for environmental variation (including lake morphometry and location), we tested whether changes in community composition differ between lakes where species introductions have and have not occurred.  We find that centrarchid introductions, due to climate induced range shifts over ~30 years, appear to negatively impact both native top predators and their prey.