For years, lush forests of kelp lined the rocky underwater reefs along the California coast. But now, these areas are barren. The reason: kelp-devouring purple sea urchins.
Sea urchins began taking over the California waters a few years ago when disease wiped out their main predator, sea stars. With the sea stars gone, urchins left their rocky refuges to roam the reefs in search of food. The hungry urchins began eating the kelp forests faster than they could grow back.
“The kelp forests will not recover without a drastic reduction of sea urchins,” explains Mark Carr, a biologist at University of California, Santa Cruz. “Releasing sea stars back into the water may help keep them under control.”