On the occasion of Ifremer's 40th anniversary, find in Var-morningevery last Friday of the month, our series on marine sciences and research issues. A monthly episode, from September 2024 to June 2025, date of the United Nations Conference on the Ocean (Unoc), organized in Nice and preceded by an international scientific congress, co-organized by the CNRS and Ifremer.
In the Mediterranean, the structuring species of the seabed are posidonia, “cymodocea”, “eelgrass”… These little-known seagrass beds are a bit like our sea meadows.
“Each of these species constitutes habitats”explains Marc Bouchoucha, ecologist and doctor in ecology at Ifremer. Macro-algae in front of Nice or “cystoseires” along the main pier of Toulon… the experiments are flourishing.
Successfully reintroducing them allows “create small forests in which organisms can settle. Restoring an engineering species makes it possible to reestablish the functions associated with a habitat.”
Shaped by humans for centuries, the Toulon coastline has become an experimental site. Many artificial reefs are submerged in ports and support biodiversity.
“Today, the biggest project that exists is 50 meters long. in the harbor of Toulon, along the Ifremer quay.”
“It would take kilometers of reefs”
Located in La Seyne, in the Brégaillon area, this quay sees populations of fish swimming that had deserted the surrounding area.. A fragile balance between human activities, inevitable pollution and recreational fishing.
“The future of fishermen is linked to the quality of eco-systems, warns Marc Bouchoucha. If we degrade them completely, the planet will recover, but there will be no more fishing.”
Preservation is not the opposite of human activity, it all depends on how it is carried out. “We see this with marine protected areas, continues the researcher. Several are popular with fishermen who request their maintenance.”
Because the fishery wealth is richer nearby. Because living things can reconnect with virtuous mechanisms, naturally.
But are the larger-scale effects measurable? “We are working on just that. The development of models in order to transpose what we know to the French Mediterranean and quantify their effects.”
A common fish from the sea bream family, the sea bream lends itself to this type of analysis. Although it is not in danger, it is under very strong fishing pressure.
“We are observing an increase in the sea bream population, yes. But to start having a significant effect, we would need to install at least 6 km of continuous habitat. Even 60 km for a large-scale effect…”
Changing scale will be necessary, whether in restoration or preservation.
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