Sea urchin population explosions following the loss of predators are devastating kelp forests, affecting the millions of species that depend on these underwater ecosystems.
Fish and marine mammals that depend on kelp forest habitat for shelter, foraging, and breeding experience welfare impacts when kelp is replaced by urchin barrens. Rockfish that hide among kelp fronds from predators lose this protection. Sea otters that need kelp for anchoring while resting cannot do so in barren areas. The cascading welfare effects of urchin overgrazing extend to species throughout the food web. Individual sea urchins in barrens that survive for years without food represent a form of prolonged stress and resource deprivation that raises welfare questions about animals with pain responses.