Valérie Derolez, Béatrice Bec, Dominique Munaron, Annie Fiandrino, Romain Pete, Monique Simier, Philippe Souchu, Thierry Laugier, Catherine Aliaume, Nathalie Malet
French Mediterranean coastal lagoons have been subject to huge inputs of urban nutrients for decades leading to their eutrophication. In response to new environmental regulations, some of the lagoons have recently been the subject of large-scale management actions targeting the waste water treatment systems located on their watersheds. To assess the rapidity and the extent of the effect of the remediation actions, we analysed data from a 14-year time series resulting from the monitoring of nutrients, biomass and the abundance of phytoplankton in the water of French Mediterranean coastal lagoons covering the whole anthropogenic eutrophication gradient. Following a 50% to 80% reduction in total phosphorus (TP) and total nitrogen (TN) urban loadings from the watershed of hypertrophic and eutrophic ecosystems, our results evidenced a rapid response (1 to 3 years) and an almost complete recovery, suggesting no hysteresis for the eutrophic lagoon. However, our findings also show that recovery patterns depend on the eutrophication status before remediation and may include feedback responses. The different responses revealed by our results should help stakeholders prioritise remediation actions and identify appropriate restoration goals.
Relevance for the Short Term Action Plan on Ecosystem
The different responses revealed by our results should help stakeholders prioritise remediation actions and identify appropriate restoration goals, especially in light of the targets of the Water Framework Directive (WFD).
- D1: Assess the efficacy and effects of implementing the ecosystem restoration plan
- D3: Share lessons learned from planning, financing, implementing and monitoring ecosystem restoration plans
Ocean & Coastal Management