Caribbean king crabs are very efficient at removing seaweed from coral reefs because they eat all kinds of algae. Too much algae can kill corals because they block out the light. Photo Credit: Courtesy of A. Spadaro
Environment USAGiant Crabs to the Rescue of Corals in the Florida Keys
The overgrowth of algae has been suffocating coral reefs in the Florida Keys, United States, but the Caribbean king crab may help solve this crucial problem: the crustacean gobbles on algae and seaweed, helping to restore the natural balance and improve overall coral health.
“We’ve had a lot of experience raising these crabs for human consumption, but I started looking at what their ecological role was on coral reefs,” says Mark Butler from Florida International University, co-author on the study published in the journal Current Biology. “And they are like reef cows, or better yet, reef goats, because they will eat almost any type of algae, and they eat a lot of it.”
Two experiments were conducted in the Florida Keys, 14 km apart, where crabs were transplanted on several reefs. After a year, data were compared to see the efficiency of king crabs to clean the coral versus scrubbing them by hand. Thanks to the crabs, the seaweed cover was reduced by 50 to 80%. Since the native crabs reduced the algae overgrowth, more baby corals have settled on the reefs, and the fish community is more abundant and diverse.
