bandeau général

During the past century, most European lakes have undergone a phase of eutrophication that altered their trophic structure and subsequently led to a cascade of ecological changes. Efforts have been undertaken to stop the external cause of eutrophication but interactions between decreased phosphorus inputs to the lake and concurrent climate change or fisheries management practices may prevent recovery along a simple reciprocal pathway.

Pelagic cladoceran, of the genus Daphnia and Bosmina, are key-species in the plankton community of lakes as regards to energy transfer along the food chain. Because Daphnia and Bosmina carapace remains as well as Daphnia resting eggs accumulated in lake sediments, these subfossil remains represent a unique biological archive to unravel the trajectory of the pelagic cladoceran community in response to environmental changes over the long term, in terms of taxonomy, size structure and genetic architecture. Using a high-resolution paleolimnological approach, this study aimed at addressing the role of human-made changes (changes in nutrient level and fish communities in a context of climat changes) on the trajectory of the pelagic cladoceran community over the last 150 years in two French deep subalpine lakes, Lake Geneva and Lake Bourget. More specifically, this study investigates i) how ‘bottom-up’ and ‘top-down’ changes affected the cladoceran community structure ii) whether such changes in community structure arise from only phenotypic plasticity or came along with changes in cladoceran genetic architecture, through analysis of mitochondrial DNA of Daphnia resting eggs.

 Keywords: food web, cladoceran, top-down, bottom-up, genetic architecture.

Publications

1. Alric, B., Arnaud, F., Jenny, J.P., Perga, M.-E. Taxonomical, size structure and genetic responses of Cladoceran communities in subalpine lakes to 150 years of human perturbations. 7^th Symposium for European Freshwater Sciences, 2011, Girona, Spain, June 2011.

2. Alric, B., Arnaud, F., Jenny, J.P., Perga, M.-E. Taxonomical, size structure and genetic responses of Cladoceran communities in subalpine lakes to 150 years of human perturbations. Cladocera Symposium, 2011, Pallanza, Italy, October 2011.