Sea otters are saving California's coast from erosion. Here's how

The marine mammals are doing millions of dollars’ worth of conservation work by rebuilding saltmarshes in Elkhorn Slough estuary. Since the mid-1980s, conservation work has seen otters rebound. And by taking a big bite out of the marsh crab infestation they’ve reduced erosion by up to 90% in the past decade, a new study found.