Understanding global climate change and agriculture impacts on freshwater ecosystems
Regime shifts in freshwater ecosystems exposed to multiple stressors
by increasing temperature, fertilizers and pesticides
Shallow freshwater lakes represent the most abundant lake type worldwide, and many of them occur in agricultural landscapes. Global climate change and local impacts can nonetheless severely affect their functioning, making them a major concern for scientists and stakeholders. In particular, shallow freshwater habitats, such as lakes and ditches, are highly vulnerable to agricultural run-off (ARO) composed of pesticides and fertilizers, additionally to heatwaves, due to their high surface-to-volume water ratios, large riparian interface and groundwater connectivity.
How would combined stressors interact on systems occurring in alternative stable states? Current state-of-art has not yet been able to predict it. Most studies primarily focused on either ecotoxicological approaches or functional community / ecosystem approaches. The overall effects of multiple stressors on complex links between different functional groups of benthic and pelagic primary producers, and associated consumers, requires therefore further investigation.
CLIMSHIFT’s ultimate objective is to actively contribute to a better mechanistic understanding of complex stressor interactions acting on shallow aquatic systems under global warming. The results of the ANR-DFG funded research project will notably contribute to the current state-of-the-art, which might be of great interest to draw the first outlines of safe operating spaces.
As specific objectives, CLIMSHIFT aims to understand and predict the response of the complex interactions of benthic and pelagic aquatic primary producers such as plants or algae, as well as their consumers, in these systems to the combined effects of global warming and agricultural run-off (ARO). Another target is to evaluate stressor interactions such as additive, synergistic or antagonistic effects based on organism physiology, community and ecosystem processes. Finally, CLIMSHIFT’s mission is to determine potential thresholds for shifts in ecosystem functions (e.g. ecosystem metabolism, energy transfer, flux of elements) for single and combined stressors.
CLIMSHIFT researchers will apply an unprecedented approach by combining both ecotoxicological stress indicators (e.g. growth and biomarkers of the different organisms) and functional community/ecosystem approaches (e.g. ecosystem metabolism and dynamics) at different temporal and spatial scales. Therefore, CLIMSHIFT will combine micro- and mesocosm studies to allow extrapolation between different levels of complexity. 4 different scenarios for the exposure of shallow aquatic systems to ARO will be tested through indoor microcosm experiments with a reduced community complexity. (cf. infographic).
Based on the results of those experiments, outdoor mesocosm experiments containing complex food webs will be established. Researchers will make benefit of data gathered in both micro- and mesocosm experiments to develop an innovative and integrative dynamical model. The latter will allow researchers to simulate other scenarios than those tested in the experiments, and thus determine critical ranges and thresholds, as well as predict potential stressor interactions.
First microcosm experiments / Dynamical model development Data analysis microcosms 2nd series of microcosm experiments /Mesocosm experiments in pond-like systems Models vs. experimental data confrontation Upscaling models from data retrieved in mesocosms Scheduled mesocosm experiments in shallow ditches – postponed because of covid-19 pandemia
First microcosm experiments / Dynamical model development
Data analysis microcosms
2nd series of microcosm experiments /Mesocosm experiments in pond-like systems
Models vs. experimental data confrontation
Upscaling models from data retrieved in mesocosms
Scheduled mesocosm experiments in shallow ditches – postponed because of covid-19 pandemia