Fatty acid analysis in an estuarine fish species to assess the health status of hydrosystems impacted by eutrophication and multistressors

The originality of this research lies in the use of fish lipid markers, which highlights the importance of fatty acid profiles as biomarkers to evaluate the health status of estuarine systems subject to eutrophication or multistress. In the present paper, we developed an approach combining lipid class and fatty acid analyses on juvenile European flounder muscle, watershed geographic metrics and pollutant levels in sediments, to assess the ecological status of seven small estuaries mainly impacted by agricultural activities in the watersheds. The estuaries showed contrasted fatty acids compositions in flounder muscle. Marked differences in polyunsaturated fatty acid (PUFA) proportions, particularly docosahexaenoic acid (DHA) and docosapentaenoic acid (DPA), reflected not only the state of cell membranes but also variations in the quality of food sources. High levels of PUFA were associated with better ecological conditions, while reduced PUFA availability was clearly linked to eutrophication and multistress. In addition, higher flounder lipid reserve content was clearly identified in the system highly impacted by fish farming, reflecting a contamination of the entire trophic chain by aquaculture waste.