In the April issue of Ecology Letters, Chevaldonné and Lejeusne found the first convincing illustration that climate change is directly affecting marine organisms. They monitored two species of endemic cave mysids (small shrimp-like crustaceans) near Marseille, France, and demonstrated that they have different tolerances to temperature.
During recent episodes of unusually warm weather, populations of the cold-loving species were replaced by congeners of warmer affinities. However, the geographical context of the Mediterranean makes it impossible for such "cold-water" species already trapped in the northernmost, coldest parts of this sea to migrate northward. A significant component of the Mediterranean biodiversity is clearly already under the threat of global warming.
Ecology Letters