Newt-fish interactions in a small forest lake

Abstract

AbstractFishes and newts may play similar roles at the same trophic level in freshwater lakes and ponds. Although a great deal is known about the predatory and competitive impact of fish on most freshwater groups, very little is known about fish-newt interactions. In the present work we have studied the influence of a fish population on the distribution and structure of a Triturus vulgaris population. The roach, Rutilus rutilus (L.), in a small forest lake were eliminated experimentally and were reintroduced after six years. Newts appeared in the lake and showed a rapid population increase after the elimination of fish. After the reintroduction offish, the recruitment of young newts virtually ceased and the population decreased. The most probable explanation is that fish prey upon newt larvae, this being supported by our field and laboratory results. Access to water bodies without significant predators and competitors is thus of vital importance for newt populations.