The coral reefs of Guadeloupe, and more broadly of the northern Antilles, have just been placed on maximum alert by the American Oceanic and Atmospheric Observation Agency (NOAA), for “severe bleaching and risk of probable mortality”, according to its bulletin dated Wednesday, September 13.
Coral bleaching is a phenomenon that occurs when water temperature increases, which can lead to the death of reefs.
The latter “are undergoing accelerated degradation linked to the increase in surface temperatures and the acidification of the oceans, while already being weakened by human disturbances associated with frequentation of the sites and diffuse pollution (sanitation systems which do not are not up to standard, in particular),” wrote the Guadeloupe Regional Climate Observatory in a report in 2020.
A phenomenon which “must increase with warming”
At the end of July, when the archipelago suffered unprecedented temperatures, particularly during the night, the local Météo-France organization affirmed that “the abnormally [high] temperatures of the surface of the Atlantic Ocean” were responsible. suffocating nights. The ocean surface temperature measured near the tip of Grande Vigie (north coast of the archipelago) “approached 30°C, a positive anomaly of around 1°C”, underlined Météo-France .
“[Friday] morning, when I came out of the water, I noticed that out of the twenty species present on the site, eighteen were affected by bleaching, and this affects corals up to 40 meters”, testified, after a reef monitoring dive, Claude Bouchon, professor emeritus in marine biology at the University of the Antilles. “Mortality depends on how long the water stays very warm,” he also said.
This wave of bleaching follows “two years of coral disease, which had already damaged the reef,” warned the scientist. According to him, one of the previous waves, in 2005, led to the loss of 40 to 45% of the reefs in Saint-Martin, in particular. “This wave is the third since that date, and the phenomenon must increase with global warming. »
According to NOAA’s Coral Reef Monitoring Service, coral reefs “provide significant ecological, economic and societal benefits, valued globally at approximately $9.8 trillion per year,” or approximately $9.192 billion. euros. Among these services, their breakwater effect, which reduces the risk of submersion, but also the shelter they represent for fish, beneficial to biodiversity and fishing activity.
