Eutrophication of peatbogs: consequences of P and N enrichment for microbial and metazoan communities in mesocosm experiments

Abstract

Complex interactions between bacteria and protists are essential to the ecosystem ecology of peatbogs. However, little is known about how short-term changes in environmental conditions may influence microbial and metazoan communities. Microbial processes and para - meters may be used as sensitive indicators of eutrophication. We address the hypothesis that an increase in the concentration of nutrients (in an experiment simulating eutrophication) will affect species richness and abundance of microorganisms and small metazoans and will cause changes in food web structure in different types of peatbogs. The experiments were performed in a Sphag- num peatland and a carbonate fen. Four experimental treatments were established (control and fertilised: +P, +N, P+N). An increase in habitat fertility was found to modify the taxonomic compo- sition and functioning of microbial communities. This was reflected in a decrease in the species richness of testate amoebae and a substantial increase in the abundance of bacteria, flagellates and ciliates in both types of peatbogs. A better understanding of which parameters regulate microbial populations in peatbogs is critical for more accurate prediction of how peatbogs will respond to global change or anthropogenic disturbances.