Salt marsh resilience compromised by crabs along tidal creek edges

by Tim Stephens, UC Santa Cruz
August 9, 2021

Coastal marshes are vulnerable to erosion caused by rising seas, pounding waves, and tidal flows. In Elkhorn Slough, these vulnerabilities are made worse by superabundant crabs found at their highest densities along the estuary’s tidal creeks, according to a new study published August 8 in Ecosphere.

The striped shore crab (Pachygrapsus crassipes) is a small crab found all along the West Coast of North America, and it is extremely abundant in Elkhorn Slough. The study demonstrated the dual role of these crabs as both consumers of salt marsh vegetation and as ecosystem engineers.

“Their burrowing weakens the creekbank edges, so that whole chunks of marsh will sometimes calve off, and by lowering biomass they are reducing the ability of marsh plants to prevent erosion,” said lead author Kathryn Beheshti, who earned her Ph.D. in ecology and evolutionary biology at UC Santa Cruz in 2021 and is currently a California Sea Grant State Fellow at the Ocean Protection Council’s Climate Change Program.

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