Three years of study as close as possible to the ocean currents. Three years during which Yann Ourmières, teacher-researcher at the University of Toulon and local manager of the European IMPACT project on the dispersion of pollutants at sea, regularly dropped buoys equipped with GPS and a transmission box in the harbor. their hull. Like his Italian colleges in Tuscany and Liguria but also in Corsica, he observed their drifts. "The idea of the project was to propose studies, on different sites in the Mediterranean, on the impact of the development of industrial ports on protected maritime areas", explains this fine connoisseur of the Port-Cros and Porquerolles national park.
The researchers did not only use buoys, they also measured currents thanks to the mesh of 200 km of coastline in high frequency radars, made possible by IMPACT. "They issue a real-time map of the current on the surface of the sea over a very large area," explains Yann Ourmières. The buoys allow for their finer vision. They can be put in the water between two islands, in very small places where radars do not necessarily manage to measure currents. To these two observation tools were added numerical models capable of forecasting the evolution of currents.
Lead, copper, etc. : a sporadic and exceptional impact
All zones combined, the study, and it is a nice surprise, rather puts the signals to the green: metallurgical contaminants (copper, lead ...) from port areas are indeed found little in marine protected areas. "Overall, in the four sites studied, there is nothing catastrophic," notes the researcher. Thus, if we take the example of Toulon, "we have high pollution rates in the small harbor, the industrial area of the port, and more and more diluted as we move away towards the large harbor then the Mediterranean ". Result: the impact is sporadic in the waters of Port-Cros and Porquerolles.
“It is a pure coincidence of the geography of the coast, which is due to the ocean circulation in the region, with a current from east to west, shade Yann Ourmières. And in certain weather conditions, due in particular to the Mistral, the small harbor can also contaminate the marine protected area, even if it remains rare. "
Plastic in ambush
Does this mean that the industrial ports of these zones can shamelessly continue to pollute? The researcher warns against a green reading of the Impact study. "The aim of the project is to identify possible interactions between port activities and marine protected areas, and to provide indications for their better management," he recalls.
For example, this data can be used to better think of the location of new developments in the bay. But above all, the study deals with chemical and invisible pollutants, not plastic pollution on the surface. This one is very present in Port-Cros and in the Mediterranean. Yann Ourmières can say it: this is one of his current research projects.
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