EcoTeBo

Human activities induce rapid climate change that poses major threats to global biodiversity, ecosystem functions, and ultimately to the fate of mankind. Forecasting and mitigating these detrimental effects is thus an urgent challenge. Warming not only increases the speed of biochemical reactions but also influences the phenotype of species trough plastic or selective processes. One ubiquitous phenotypic response to climate change is the reduction of ectotherm body size with temperature—the warmer it is, the smaller they get—. This temperature-induced body size shift has been proposed as the third universal species response to global warming altogether with shifts in phenology and species geographical distribution. However, the ecological consequences of temperature-induced body size shift on communities remain largely unexplored. This is an important gap, both for fundamental and applied research, as body size determines many ecological properties such as fecundity, growth rate, trophic position and community stability. Thus, knowledge of how temperature-induced body size shift modulates species interactions is important for understanding and predicting climate change impacts on ecological systems. The project EcoTeBo combines modelling and experimental approaches to investigate the ecological consequences of warming and body size shift on trophic interactions, community dynamics and ecosystem functions. EcoTeBo focuses on top predator body size reduction because (i) body size reductions appear to be stronger at high trophic levels and (ii) top predator body size is an important determinant of food web stability, especially in aquatic food webs that are strongly size-structured and top-down regulated. To achieve this ambitious objective, EcoTeBo brings together researchers with highly complementary expertise on trophic interactions, community ecology, ecosystem functioning, aquatic ecosystems, ecological models and management of large experimental infrastructures. By simultaneously manipulating temperature and top predator body size in simple and complex freshwater systems, we will provide: (1) A unique experimental test of the ecological impacts of temperature-induced body size shifts on the strength of trophic interaction, community dynamics, and ecosystem functions. (2) An unprecedented assessment of the relative effects of temperature and top predator body size on trophic interactions and community dynamics by combining modelling and experiments at different levels of complexity (i.e. food chain and whole community). (3) Novel food web models accounting for phenotypic responses to temperature with predictions connected to the stability of freshwater ecosystems, in terms of both their temporal variability and persistence. To our knowledge, EcoTeBo would be one of the first project to investigate the consequences of temperature-induced body size shifts on different components of trophic interactions, community dynamics and ecosystem functions. By exploiting the synergies between new theories and experimental tests in simple and more complex freshwater systems, we will disentangle the relative effects of temperature and body size shift on various ecological features and identify the mechanisms driving these effects. In addition to novel and important scientific results, EcoTeBo will facilitate the integration of trait based approach into climate change research and ease the detection and mitigation of climate change impacts by developing predictive models and using body size as a bio-indicator of ecosystem functioning.