Contribute to improving knowledge and diagnosis of the ecological status of Breton estuaries by developing biological and environmental markers for sustainable management of hydrosystems
Partenaires Du Projet
Projet Ecoest
Project objectives
The estuaries of Brittany play an essential role in the ecological functioning of coastal areas and in regional economic activities (shellfish farming, fishing, tourism). However, these environments are subject to significant agricultural, urban and industrial pressures, which alter water quality and biodiversity.
The ECOEST project, jointly led by LEMAR and CEDRE, with the support of the Loire-Bretagne Water Agency, aimed to provide a comprehensive assessment of the ecological status of eleven Breton estuaries, using a multidisciplinary approach combining geography, chemistry and biology.
This approach sought to identify the main environmental stress factors (eutrophication, contamination by organic and metallic pollutants, thermal and/or hypoxic stress) and their effects on aquatic organisms, in particular on a sentinel fish species in estuaries: the flounder (Platichthys flesus).
The results of this project made it possible to:
Better understand the interactions between anthropogenic pressures and water quality;
Produce biological markers that can be used for the diagnosis and biomonitoring of hydrosystems;
Provide managers (SAGE, local authorities, Water Agency) with decision-making tools for the restoration of estuarine ecosystems.
Methodology
The project was based on an integrated multidisciplinary approach, combining:
Geographical analysis of catchment areas (land use, agricultural and urban uses, hedgerow density);
Environmental chemistry (measurement of organic pollutants, pesticides and metals in water, sediments and fish);
Biology and proteomics of flounder, to detect physiological and molecular alterations linked to various stressors.
These cross-referenced data made it possible to classify Breton hydrosystems according to their degree of anthropisation and to define reference systems, less impacted, to support the sustainable management of estuaries.
Main findings
Ecological typology of Breton estuaries: A classification of hydrosystems has been established based on the level of anthropisation and water quality.
Identification of environmental stressors: Analyses revealed high levels of nitrates (up to 60 mg/L) and pesticides (up to 6.9 µg/L) in the most agricultural basins. Metal (lead, zinc, copper) and organic (PAHs, PCBs) contamination was also observed in sediments and fish.
Innovative biological approach: Monitoring of flounder, a sentinel fish species in estuaries, made it possible to link environmental pressures to physiological and molecular alterations measured by molecular biology (high-throughput proteomics). This work has led to the proposal of biological markers (liver proteins, lipid profiles in muscle, stable isotopes and trace elements in otoliths) for assessing the health of hydrosystems.
Management tools: ECOEST has produced a series of integrated geographical, chemical and biological metrics and indicators to support biomonitoring and restoration actions carried out by SAGEs and local authorities.
Outlook
The project results pave the way for a new generation of biomonitoring tools that integrate molecular biology with traditional environmental monitoring.
They will help refine the diagnoses of the Water Framework Directive (WFD) and improve the integrated management of Breton estuaries in the face of increasing anthropogenic and climatic pressures.
