Invasive crabs help Cape Cod marshes

Conquering hero

Just the sight of Carcinus maenas, the invasive green crab, sends marsh grass-eating Sesarma reticulatum crabs running for their lives. The marshes and their grasses slowly recover. Credit: Catherine Matassa/Northeastern University

Ecologists are wary of non-native species, but along the shores of Cape Cod where grass-eating crabs have been running amok and destroying the marsh, an invasion of a predatory green crabs has helped turn back the tide in favor of the grass. The counter-intuitive conclusions appear in a new paper in the journal Ecology.