In the Mediterranean, the warming waters have brought with it several invasive species. Among them, a tropical fish, the Siganus or rabbitfish: a plague for algae and seagrass, essential resources for local species.
Bad omen fish: among the concrete examples of global warming, there is the appearance in the Mediterranean Sea of hundreds of tropical species. And they are wreaking havoc. It is estimated that more than a hundred tropical fish have settled there, threatening biodiversity with their presence.
This is the case, for example, of Siganus, a small fish native to the Red Sea, which is also called the rabbitfish. Not as cool as the name might suggest. Off the Turkish coast, in Antalya, diving enthusiasts have followed the installation of the rabbitfish. And its devastation. “All the rocks are bare because they are eating all the algae that grow, laments Murat Draman, head of a diving club. It’s a bit like the surface of the Moon, everything is white in the first 15-20 meters. They are turning these areas into desert.”
For the moment the rabbitfish is established in the northeast of the Mediterranean, its territory stops in the south of Sicily. It was even seen on the Marseille coast thirteen years ago, but it is not yet established in France.
Arrival via the Suez Canal
Several factors explain the species’ journey from the Red Sea to the Mediterranean. Its arrival was first favored by the opening of the Suez Canal, which created a link between the Red Sea and the Mediterranean, then by the effects of climate change: the Mediterranean is the sea that heats up the fastest. And that’s kind of a green light given to these rabbitfish. ” For a very long time they were confined to the east of the Mediterranean, and since the beginning of the 2000s, we have started to see it spreading a little more to the North, to the West “, explains Christophe Lejeusne, researcher at the Mediterranean Institute of Biodiversity and Marine Ecology.
With global warming, the entire Mediterranean is warming up. Warm waters move and this opens up more and more ecological niches for species that love warm waters.
Christophe Lejeusne, researcher at IMBE
This presence and colonization endanger the biodiversity of the sea. It is sort of the burned earth policy: for because of her diet, fish-rabbit destroys the habitat and species of local resources, attacking algae and seagrass, according to Sébastien Villager, a researcher at CNRS: ” All invertebrates, in particular certain crustaceans but also fish, need these habitats, for there at least juvenile stage, to feed themselves, hiding in what are called nurseries. There is a two-fold decrease in the number of species, both invertebrates, and fish, in areas where Siganus are very abundant.”
In a study published this summer, WWF warns about the impact of invasive species and the state of the Mediterranean. On the one hand, warming is paving the way, on the other hand, overfishing weakens the predators of these exotic fish. For Ludovic-Frère Escoffier, head of the Ocean Life program at WWF, it is an explosive cocktail: “There is a 40% reduction in the number of native species in this region. So we are really facing a problem of biodiversity and climate.”
A situation that will get worse?
According to WWF, nearly 1,000 species, including 126 fish, have migrated from the Red Sea to the Mediterranean. On their way, Bela Galil is on the front line. She lives in Israel and has worked on the subject for half a century at the Tel Aviv Museum of Natural History. “We have 460 invasive species along 190 km of coastline, explains Bella Galil. 90% of them have passed through the Suez Canal. They have spread faster and faster and further and further into the Mediterranean.”
The solution to trying to support native species would include restoring ecosystems and more targeted fishing, according to WWF. The rabbitfish is not the most disturbing exotic species. Lionfish, for example, are poisonous and attack other fish directly, not just their environment.
