Relations between planktivorous fish and zooplankton in two very shallow lakes of the Pampa Plain

Abstract

Introduction It is widely accepted that predation plays a critical role in determining zooplankton community structure in ponds and lakes. The relationship between fish planktivory and zooplankton species composition has been discussed since the early work of HRBACEK et al. (1961) and BROOKS & DODSON (1965). Size-selective predation by fish may produce changes in zooplankton community structure. Phenomena frequently attributed to heavy planktivory include the small individual size of cladocerans and the reduced representation of the vulnerable Daphnia sp. (BROOKS & DODSON 1965). A strong relationship between fish assemblage and zooplankton was proposed from results from a large set of Argentinean lakes (QUIRS 1995). Fish assemblage was stated as the principal factor affecting phytoplankton and macrozooplankton biomass, once nutrient concentration has been taken into account. Lakes with planktivores, but without piscivores, had the lowest macrozooplankton biomass (QUIRS 1998). The m