PhD Position – Are ecological indicators climate-proof? Reassessing pressure–response relationships in estuarine fish communities in an era of global change

You will join the Aquatic Ecosystems and Global Change (EABX) research unit, which focuses on the responses of estuarine and freshwater biodiversity to global change. You will carry out your PhD within the Estuarine Ecosystem Functioning and Restoration and Amphihaline Migratory Fish Populations (FREEMA) research team, which investigates the functioning of estuarine ecosystems and the ecology of migratory fish species of conservation concern. The main objective of this PhD project is to assess the impact of environmental changes on the ecological status assessment of estuaries and explore potential adaptations to ensure the reliability of these assessments in the context of climate change. The project will build on fish community monitoring data collected since the early 2000s across several dozen estuaries in France. It will be structured around four complementary research objectives: Characterise changes in environmental conditions and anthropogenic pressures in the studied estuaries to identify factors that may influence ecological status assessments. Investigate changes in pressure-response relationships between anthropogenic pressures and fish community responses by comparing statistical relationships across different periods and assessing their implications for reference conditions and ecological status classifications. Explore ways to incorporate environmental changes into ecological assessment methods, particularly by including hydroclimatic variables in statistical models or introducing metrics sensitive to environmental changes. Assess the ecological relevance and operational suitability of the metrics used in the Estuarine and Lagoon Fish Index (ELFI), by examining their sensitivity to environmental changes and exploring the potential value of new metrics, particularly those derived from functional ecology. Expected outcomes This PhD project will provide a better understanding of how environmental changes influence the relationships between anthropogenic pressures and estuarine fish community responses. It will aim to identify potential biases associated with the use of historical reference conditions and propose improvements to the ELFI index to enhance the robustness and reliability of ecological status assessments and their relevance for the management of transitional waters under the European Water Framework Directive (WFD).