Classification de l′état écologique du réservoir Marne via l′utilisation de 3 métriques : Chlorophylle a, indice planctonique lacustre et phosphore total

Abstract

Phytoplankton is a key element to assess ecosystem water quality in the context of the European water framework directive. The recent work of De Bortoli and Argillier (2008) allowed the construction of ecological status class boundaries for chlorophyll a and total phosphorus for national ponds and the lacustrian planktonic index of Barbe et al. (2003) is used to define the trophic level of lakes, reservoirs and ponds on the basis of the relative abundance of some algal classes. We used these three parameters from data obtained at 4 sampling stations of the reservoir Marne in 2006 and 2007. Our results highlight that, for the reference station called H and the station J (north-western basin), the ecological status is good to moderate and that the trophic status is mesotrophic. For stations G (Lake Champaubert) and K (south-eastern basin), however, waters are eutrophic and characterised by a moderate to bad ecological status. These results point out the difficulty to use these metrics to conclude on the ecological status of the whole reservoir Marne, owing to the ecosystem spatial heterogeneity. © 2011 EDP Sciences, SETE.