Overfishing of urchin predators, in combination with natural disturbances, has been linked to an increase in the occurrence of urchin barrens. Marine reserves have been proposed as a means to re-establish the interactions between urchins and their predators in California kelp forests. Whether increased densities of lobsters and other predators in reserves are sufficient to convert barrens back to kelp forests depends on the degree to which predators avoid urchins from barren habitats.

Below the gently rolling waves off the Palos Verdes Peninsula, a spiny purple menace is ravaging what should be a thriving kelp forest.