Coastal marshes are vulnerable to erosion caused by rising seas, pounding waves, and tidal flows.
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.
Beheshti and her coauthors conducted a five-year field experiment to assess the effects of crabs on the vegetation and sediments along eroding creekbank edges. Using fencing and traps made of empty tennis-ball cans to exclude crabs from experimental enclosures, they found that reducing crab abundance led to increased growth of salt marsh vegetation and enhanced sediment density.
Read more at University of California - Santa Cruz
Image: 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. (Credit: K. Beheshti)
