09/14/2026
A predator’s return did more than restore wildlife to one California estuary.
It helped rebuild the habitat itself.
Sea otters recolonized Elkhorn Slough in Monterey County in 1984, when nutrient pollution had pushed eelgrass to an all-time low of two hectares.
The comeback triggered a trophic cascade.
By eating crabs, otters freed small grazers such as sea slugs to consume algae that can smother eelgrass leaves.
A 2013 PNAS study found eelgrass area had expanded 600 percent since the otters returned, despite nutrient loading.
Their influence reached the marsh too.
A 2024 Nature study found otters suppressed burrowing crabs that eat marsh roots and weaken creekbanks.
Where otters were abundant, marsh-edge erosion slowed by an average of 69 percent as vegetation strengthened the banks.
One returning predator reshaped food webs, plant growth, and even the shoreline.
Elkhorn Slough shows how one restored predator can help an ecosystem recover.