Original paper

Food web properties in aquatic microcosms with litter mixtures are predictable from component species

Schädler, Martin; Rottstock, Tanja; Brandl, Roland

Abstract

Many aquatic systems depend on allochthonous organic matter. Quality of litter differs between plant species. Therefore, the composition of the surrounding vegetation may influence litter decomposition and other processes in aquatic food webs. We recorded the abundance of insect larvae, as well as the diversity of cultivable fungi and bacteria, the metabolic diversity of the microflora, and leaf litter decomposition rates in aquatic outdoor microcosms, using litter from four broad-leaved tree species and a mixture of the four litter types. Diversity of fungi, abundance of bacteria and functional diversity of the microflora and decomposition differed between microcosms with litter from each of the four tree species. For microcosms with the mixture of litter, observed values of all measured variables did not differ from the expectations derived from microcosms with litter from only one tree species. We conclude that specific traits of the component litter species (e.g. C/N ratio) outweigh possible non-additive effects in mixtures. Our results contrast with findings in terrestrial systems where decomposition rates of mixtures are not always predictable from the rates measured for the component species.

Keywords

allochthonous litterlitter decompositionmicroflorainsect larvaetemporary ponds