INVASION BY A NATIVE SPECIES: CONSEQUENCES FOR POPULATION DYNAMICS AND DIET OF A NON-NATIVE SPECIES.
Invasive species have become established in some aquatic communities and these altered communities can persist through time. However, altered communities can themselves be subject to invasion by regionally native species. In a small pond with a long-established population of non-native western mosquitofish (Gambusia affinis), I examined the consequences of a natural invasion by the native longear sunfish (Lepomis megalotis), on the population dynamics and diets of both fishes. In the two years post-invasion, mosquitofish declined as sunfish increased. Longear had a broader diet than mosquitofish; consuming crayfish, salamander larvae, mosquitofish, zooplankton, and macroinvertebrates. For prey items consumed by both fishes, cladocerans declined and chironomids increased in the diets of mosquitofish post-invasion. In contrast, the diets of longear showed no difference in cladoceran abundance between years, but chironomid abundance in the diets declined. Thus the invasion of the native longear sunfish had a negative effect on the abundance of the established non-native mosquitofish and altered their diet, suggesting that native longear have the potential to regulate populations of the non-native mosquitofish.
Jessica Rettig (Primary Presenter/Author), Denison University, firstname.lastname@example.org;