Lundi 15 février à 11h, Aline Waterkeyn (Laboratory of Aquatic Ecology and Evolutionary Biology – Belgique) présentera à la Tour du Valat un séminaire intitulé « Community structuring factors in Mediterranean temporary wetlands » dont vous trouverez ci-dessous le résumé en anglais.
« Despite the recognized importance of Mediterranean temporary wetlands as priority habitat for biodiversity conservation and ecosystem services (Habitat Directive), our current understanding of diversity patterns, ecosystem functioning and community structuring processes in this habitat is still incomplete. We studied key environmental factors, biotic interactions and dispersal dynamics shaping invertebrate communities in temporary wetlands of the Camargue. Since these habitats are particularly susceptible to changes in the quantity and quality of their water supply, we discuss our results in the light of predicted scenarios of climate change and intensive water management.
Results from a field survey of 30 temporary wetlands showed that salinity and hydroperiod were the most important community structuring factors and that dispersal was probably not limiting. We then investigated the interacting and long-term effects of salinity and hydroregime on active and dormant crustacean communities using a large scale outdoor mesocosm experiment. The interacting effects of both stressors significantly influenced diversity, density, reproduction, succession and overall community structure (active and dormant). Although resting egg banks can temporarily buffer against unfavorable conditions, our results suggested that persisting bad conditions may lead to their exhaustion within four to ten years. Based on our results we conclude that predicted aridification may lead the loss of species that come late in the succession, while salinisation may lead to the loss of already fragile freshwater species. We also argue that predicting the effects of changing environmental factors is not always straightforward, since they are often complicated by unknown sublethal effects, indirect abiotic effects or changed biotic interactions, such as, in our case, the strong interactions between large branchiopods and zooplankton. »