Kelp Forest

Kelp forests are among the world's most productive ecosystems, supporting 800+ species. The classic trophic cascade: sea otters eat sea urchins, sea urchins eat kelp holdfasts. When otters were hunted to near-extinction, urchin populations exploded and created urchin barrens — rocky seafloor stripped of all kelp. Reintroducing otters allowed kelp to recover, demonstrating top-down ecosystem control. Click the ocean to add disturbances; warm water events (El Niño) weaken kelp stipes.