Kurzfassung

The breakdown of allochthonous coarse particulate organic matter like leaf litter is a fundamental function in freshwater ecosystems providing energy for local but also downstream communities. Although the importance of the microbial conditioning process on this leaf litter is well known, implications of antimicrobials in this process and a potential transfer to leaf shredding organisms is largely unknown. Single studies indicate that antibiotics may positively affect the feeding preference...The breakdown of allochthonous coarse particulate organic matter like leaf litter is a fundamental function in freshwater ecosystems providing energy for local but also downstream communities. Although the importance of the microbial conditioning process on this leaf litter is well known, implications of antimicrobials in this process and a potential transfer to leaf shredding organisms is largely unknown. Single studies indicate that antibiotics may positively affect the feeding preference of leaf shredding amphipods, while the opposite is true for fungicides. However, mixtures of antibiotics and fungicides were not yet assessed, albeit they may occur together in the field. Moreover, it is still unknown, whether an altered feeding preferences is indicative for implications in the physiology of shredders at the level of individuals and even populations. Therefore, the present proposal suggests a tripartite experimental set-up. First, an antibiotic, a fungicide and a mixture of both will be applied at various concentrations during conditioning of leaf discs. These leaf discs will subsequently be offered amphipods allowing for differentiation among those conditioned in the control or in one of the antimicrobial treatments. Constitutively, a two-factorial test design will assess the contribution of food quality related effects as well as the implications of direct exposure via the water phase on the combined exposure scenario considering both exposure pathways on the physiology of shredders over multiple weeks. A final experiment will investigate whether the implications on the level of individuals translate into population level effects. All experiment will be accompanied by the characterisation of the leaf associated microbial community and its nutritious value allowing for inferences of the food quality and the observed effects. » weiterlesen» einklappen