Sea otters returned to a California estuary; eelgrass expanded 600%, marsh-edge erosion slowed 69%

Sea otters returned to California’s Elkhorn Slough in 1984 when pollution had severely affected its ecosystem. Their recovery triggered changes across the food web, helping eelgrass beds expand by 600%. A later study found marsh-edge erosion slowed by an average of 69%, as otters reduced populations of root-eating crabs.