Oceans and climate

To study the relations between men, seas and climate

The oceans provide cheap food for many people around the world. As a result, the economic weight of fishing is considerable. However, for several years we have observed a stagnation of this seemingly inexhaustible manna, as well as a general decrease in the size of the fish. Is this situation the result of overexploitation of marine species, global warming or the combination of these two factors? What development can we predict today?
Scientists now have the means to answer these questions. To this end, the Eur-Oceans program has just been launched in Paris, supported by the European Union, whose scientific direction is provided by two French people: Paul Tréguer, director of the European University Institute of the Sea (Brest, Finistère) and Louis Legendre, head of the oceanographic laboratory in Villefranche-sur-Mer (Alpes-Maritimes). However, "to understand what will happen in the next fifty years, it is necessary to know what has happened over the past fifty years", explained Mr. Tréguer during the Eur-Oceans conference which took place. held in Paris on April 14 and 15, and which was opened by François d'Aubert, Minister responsible for research.
Indeed, marine ecosystems turn out to be much more complex to understand than their terrestrial counterparts, especially as they interact with each other. Their response to hydro-climate change will also be more brutal than on land. To apprehend them, it is therefore necessary to bring together technical means (satellites, ships, buoys, models) and skills that are now dissociated: marine physicists and chemists, biologists who are experts in the marine environment and specialists in a modern approach to fisheries. .
Studying the interactions between climate, oceans and marine ecosystems at the planetary level, Eur-Oceans will focus on certain key regions: the North Atlantic, coastal systems and the southern ocean. 160 scientists from 66 marine institutes from 25 countries are expected to work for this program. France participates in it through the CNRS, Ifremer, IRD, CEA and CNES. The project budget reaches 40 million euros over four years, of which 30 are provided by research organizations and 10 by the European Union. Eur-Oceans has the status of "network of excellence" whose main objective is to remedy the fragmentation of European research. It is also associated with the international Imber program (Integrated Marine Biogeochemistry and Ecosystem Research), headquartered in Brest. Collaborations are also planned with the United States, Canada, Australia, Japan and Namibia.
The disappearance of the cod off the coast of Canada has struck a lot of people and raised awareness. After a period of stability, the results of the cod fishery in 1992 collapsed sharply. The Canadian authorities banned its fishing for ten years, but the return of this fish to the region is still awaited. At the origin of the problem, a modification of a component of the ecosystem due to man. By a phenomenon of trophic cascades, we now find in the region a lot of shrimps and crabs. Seals, predators of cod, increased their catches, correspondingly reducing the number and size of cod, and therefore the quantity of eggs. However, "when you are small, you are eaten by everyone because the size of the mouth is linked to predation", explains Philippe Cury, director of the Mediterranean and Tropical Fisheries Research Center (Ifremer, Sète, Hérault). “Now,” he says, “we need to develop an ecosystem approach to marine resources, whereas previously the problem was studied sectorally. "

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Suite and source: Christiane Galus, The World, 15 / 04 / 05 LeMonde

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