Sea otters nature engineers

Sea otters, with their voracious appetite, play a crucial role in erosion control and the restoration of coastal wetlands. Once on the brink of extinction along the California Central Coast, USA, sea otters have made a significant comeback thanks to an extensive reintroduction program. They have recolonized Elkhorn Slough, California's second-largest estuary. Currently, about 100 sea otters inhabit the slough, where they feed, nest, and nurse. Now researchers have found that their insatiable appetite for plant-eating marsh crabs has contributed to stabilizing the area's marshlands. Since the reintroduction of otters, they have effectively controlled the crab population, which helps maintain the stability of the salt marshes and creek banks. The accompanying images depict the researchers, the studies, the environment, and the species involved in this intricate web. Published in BBC Wildlife, May 2025.

Kathryn Beheshti, a UCSC doctoral candidate shows samples of tidal marsh vegetation. The pickleweed showed in the right is very important for the overal health of the marsh and for bank stabilization. Elkhorn Slough National Estuarine Research Reserve. Watsonville, California, USA, September 18, 2019.

A sea otter feeds in the slough while her pup rests next to her. Elkhorn Slough National Estuarine Research Reserve. Watsonville, California, USA. July 8, 2024.

A shore crab hides in its burrow in the banks of the Elkhorn Slough. These crabs burrow along creek margins and are abundant in some areas of the slough. Elkhorn Slough National Estuarine Research Reserve, Moss Landing, California. July 8, 2024.

Kathryn Beheshti, UCSC doctoral candidate, in the field with Alexandra Thomsen, CSUMB graduate student. They are performing measurements in the tidal marsh vegetation in Elkhorn Slough National Estuarine Research Reserve. Watsonville, California, USA, September 18, 2019.

A shore crab eating algae. Elkhorn Slough, Moss Landing, California, USA.

Kathryn Beheshti, a UCSC doctoral candidate, researches plant-invertrebate interaction within the tidal marshes of Elkhorn Slough. In this picture she checks a predator-exclusion experiment for shore crab burrows. The results of the experiment are that without sea otters crab population and burrowing increased while plant cover decreased significantly. Elkhorn Slough National Estuarine Research Reserve. Watsonville, California, USA, September 18, 2019.

View overlooking the slough, Moss Landing Power Plant and the Harbor from Jetty Road in Moss Landing State Beach. Moss Landing, California, USA, September 19, 2019. The slough is the United States first estuarine sanctuary and is a RAMSAR wetland.