Long-term dynamics of Asplanchna priodonta in Lake Windsborn with comments on the diet

Abstract

We evaluate trophic interactions between the rotifer Asplanchna priodonta and the plankton community of Lake Windsborn (Eifel District, Germany). The long-term population dynamics of this species and of the two most abundant zooplankton species, Keratella cochlearis and Bosmina longirostris, were analyzed in relation to hydrochemical and climatic variates. The maximum abundance of A. priodonta was limited to the summer months with temperature being the only significant predictor of abundance. Intrinsic rate of growth and abundance of the three species were independent from each other suggesting the absence of trophic interactions. In Lake Windsborn, A. priodonta was a grazer rather than a predator. Its diet included high proportions of colonial algae and cyanobacteria which cannot be ingested by the other abundant zooplankton species, whereas zooplanktonic food were rarely found. Thus, our study supports the hypothesis that A. priodonta is an opportunistic feeder whose trophic position entirely depends on the structure of the plankton community.