Sea Urchin Population Explosion in Southern California Coastal Waters

The alleged population "explosion" of coral-eating sea stars (Acanthaster planci) in the west tropical Pacific (1) be comparable to the apparent population "explosion" of herbivorous sea urchins (Strongylocentrotus franciscanus S. purpuratus) along the coast of southern California. Many luxuriant kelp beds, supporting a rich association of other organisms, have all but disappeared during the past few decades, and in the place of the holdluxuriant holdfasts barren areas supporting extremely dense populations of the urchins (2).