Trophic characterization of Orestias (Teleostei: Cyprinodontidae) in the Lauca National Park

Abstract

Fish exhibit a wide diversity of feeding behaviors, sometimes associated with specific morphologies, which may reflect adaptations to exploit the resources depending upon where they live. In isolated aquatic systems, fish provide a good model to study species trophic relationships. The present study evaluates the diet of five species of Orestias which inhabit eight different sites of the Arica and Parinacota Region,Lauca National Park, Chile. We analyzed 177 stomachs of Orestias chungarensis, O.laucaensis, O.parinacotensis, O. piacotensis and Orestias cf agassii. For the analyses we used quantitative descriptors of number of prey items and frequency of occurrence. We analyzed the richness and abundance of prey,diet overlap by species and by location. We analyzed diet composition using an analysis of correspondence (DCA). The diet of Orestias consisted of zooplankton and macroinvertebrates associated with macrophytes such as Cladocera (Chydorus, Daphnia, Alonella), Ostracoda (Cyprinotus). Amphipoda (Hyalella), Mollusca (Biomphalaria) and Insecta (Chironomus). The variation in prey richness and diet amplitude observed among the studied populations of Orestias may reflect an opportunist trophic strategy of these species, consuming the prey species which are most frequent, thus no showing trophic differentiation among them.