Disentangling food webs interactions in the littoral of temperate shallow lakes

Abstract

Elucidation of food web interactions provides better understanding of ecosystem functioning, indicates anthropogenic impacts which often cause alterations in environmental conditions and detoriorations in feeding network in terrestrial and aquatic ecosystems. The importance of microfauna and macroinvertebrates in littoral zones of shallow waters has poorly been studied regarding their trophic interactions. This study compares invertebrate assemblage and food web interactions among epiphyton, zooplankton and benthic macroinvertebrates across structural heterogeneity in the littoral zone of three temperate shallow water bodies. Submerged and structurally-complex stands of Ceratophyllum demersum inhabited higher abundance of cladocerans and supported higher diversity and biomass of epiphytic protozoans and invertebrates in comparison to floating-leaved Nuphar lutea stands. Analysis of the ecosystem functioning illustrated the increased biomass of macroinvertebrate predators and a preference of predation over planktonic crustaceans in more complex macrophyte stands. Food webs displayed higher complexity and size with habitat heterogeneity, while epiphyton and zooplankton shared the important fraction in food resources among the invertebrate trophic network. Results of food web modelling indicated zooplankton and epiphyton as more vulnerable to invertebrate predation in the complex submerged macrophytes than in floating-leaved macrophyte stands. Integrated community, ecosystem and food web approaches in explanation of complex trophic interactions in the littoral zones justified an increase in diversity and food-web functional complexity with structural heterogeneity of microhabitats.