DOES IT IS POSSIBLE TO EVALUATE THE EFFECTS OF CREATION OF ESTUARINE INTERTIDAL MUDFLAT THROUGH THE MACROBENTHOS?
Last infrastructure developments along Seine estuary (Normandy Bridge and Port 2000) have generated creation of mudflat to balance long term decrease of intertidal zone. North mudflat plays important role as nursery for several fishes, and is essential for shorebirds and waterfowl. Macrobenthic data (1987 to 2006) show very strong intra and inter annual variability’s. Nevertheless, trends show a decrease for N. diversicolor suggesting a relationship between its occurrence and the sedimentology with two successive periods (1987-1997 and 2000-2006) correlated within the annual river flow. Similar trends were identified for C. volutator and M. balthica which are sensitive to mudflat surface changes and to meteorological variables: freshwater input, sediment change from mud to sandy mud due to decrease of freshwater flow. No relationship was observed for S. plana. This study illustrates the difficulty to identify relevant indicators to determine the effects of restoring estuarine functions
