a worrying wave of mortality hits a species of coral

With their dazzling colours, gorgonians are a signature of the Mediterranean seabed. They are a species of coral, a refuge for other animals. For a month, they have been withering away. In a few days, the colorful forest disappeared. Only white skeletons remain. In Marseille (Bouches-du-Rhone)the diving clubs issued the alert first. At the end of August, they discovered their devastated emblematic site. Faced with the emergency, scientists are increasing observation missions off the creeks.

Every day, marine biologists from Northern Environment, a research institute, dive to document the mortality of gorgoniansconcentrated in 10 and 30 meters depth. Near the island of Riou (Bouches-du-Rhone)close to 90% of gorgonians are dead, necrotic. “We risk seeing fewer and fewer gorgonians in Marseille on the depth section greater than 30 meters, but the species is not in danger”reassures Tristan estaquemarine biologist at Septentrion Environnement.

During the summer, the heat wave did not spare the underwater world. The sea temperature sometimes rises at 28°C at 30 meters depth, from never seen. “We know that heat is one of the major factors that explain mortality. Most likely combined with other elements. And these are the ones we seek to study”explains Solène Basthard-Bogaindeputy director of the research institute.