Wastewater Discharge, Seagrass Decline and Algal Proliferation on the Cote d'Azure

In certain regions of the northwestern Mediterranean Sea, areas that once were dominated by the seagrass Posidonia oceanica have experienced massive proliferations of the green alga Caulerpa taxifolia. In these regions of alga proliferation, sediments exhibited high rates of exoenzyme activity, increased NH sub(4) super(+) concentrations, and elevated production rates. Sediments in these regions are also characterized by low capacities for transforming organic N into NH sub(4) super(+) with respect to the amount of organic material available. High phosphorus concentrations were also detected in the sediments. These symptoms are characteristic of waters that have been polluted with urban wastewaters. Potential sources of the wastewaters causing problems in this region are identified.