Tierökologie

Food web ecology of aquatic detritus-based ecosystems: Including minute actors to complete the picture

Minute organisms are diverse, abundant and perform key functions in ecosystems. As such they can provide relevant empirical clues to feed and test general ecological theoretical framework. However, a small size does not ease manipulation and taxonomical assessment. Although new techniques such as metagenomics and stable isotopic probing have begun to open the 'microbial black box', research gaps still persist however, and it is becoming urgent to assess, not only the genuine role of bacteria, but also that of protozoans and micro-metazoans (e.g. aquatic meiofauna). Because decomposition of terrestrial detritus (e.g. plant litter) is a key function of forested stream ecosystems, this research project basically aims at 'completing the picture' of instream decomposition processes by including protozoans and meiofauna in a realistic and highly resolved food web. To challenge this aim, both in situ integrative and laboratory targeted approaches are planned, using cutting-edge methods such as compound specific stable isotope analysis and metagenomics. More specifically, outcomes of this project would shed light on so far neglected functional role of meiofauna and protozoans in the partitioning and trophic transfer of decomposition products. In an integrative context, this project will also concern predator-prey interactions &ndash in the widest sense &ndash by exploring direct and indirect pathways of predator controls on decomposition dynamics. This project is expected to help disentangle the strength of trophic versus non-trophic interactions &ndash especially at the smallest scale and in complex litter habitats, where predator foraging success is expected to be highly constrained by micro-habitat features and by antipredator responses of prey.

Research Expertise

• Design of ecological experiments in situ and in the laboratory
• Chemo-taxonomy, stable isotopic analyses and stable isotopic probing
• Multivariate analyses, path modeling