When sea otter, sunflower sea star, and other predator populations collapse, sea urchin populations can explode and overgraze kelp forests.
Fish and invertebrate communities dependent on kelp forests experience severe welfare impacts when urchin barrens replace productive kelp habitat. Fish lose shelter and feeding areas, driving population declines. The ecological cascade from predator loss through urchin boom to habitat destruction demonstrates how individual animal welfare is embedded in ecosystem health.