10th Symposium on Cladocera location:Lednice, Czech Republic date:28 September-3 October 2014
Environmental changes often weaken hosts or induce host responses, which may result in a severe disease outcome. We investigated if the interaction between toxic cyanobacteria and parasite exposure depends on the host population response with respect to its eutrophic history. We exposed Daphnia magna clones to the toxic cyanobacterium Microcystis aeruginosa and a virulent parasite that causes White Bacterial Disease. Our results show that a Daphnia population with eutrophic history is more susceptible to the disease upon exposure to toxic M. aeruginosa than a Daphnia population with oligotrophic history. This observation can be mechanistically linked to a difference in feeding rate with respect to the toxic cyanobacteria. These results show that the interaction between parasites and cyanobacteria is context dependent and that trait-mediated indirect effects (TMIEs) evolve upon exposure to natural occurring toxicants, which in turn affect disease outcome in Daphnia.