European green crab

European green crab
Hans Hillewaert · CC BY-SA 4.0 · source
Name	European green crab
Status	Invasive in many regions
Regnum	Animalia
Phylum	Arthropoda
Classis	Malacostraca
Ordo	Decapoda
Familia	Portunidae
Genus	Carcinus
Species	C. maenas

European green crab is a small coastal arthropod originally native to the Atlantic Ocean coasts of Europe and North Africa. It has become a globally distributed invasive species, establishing populations in the Atlantic and Pacific basins and radically altering many estuarine and coastal wetland ecosystems. Notable impacts have drawn attention from organizations such as the International Union for Conservation of Nature and national agencies including the United States Fish and Wildlife Service, the Canadian Wildlife Service, and the Australian Department of Agriculture, Fisheries and Forestry.

Taxonomy and Description

Taxonomically placed in the family Portunidae and described in early 19th-century European zoological literature, the species was recognized in works contemporaneous with taxonomists like Carl Linnaeus and later catalogues produced by institutions such as the Natural History Museum, London. Adult carapace width typically reaches 60 mm, with five marginal teeth on the anterolateral carapace and three spines on the dorsal carapace region used for identification in keys held by museums like the Smithsonian Institution. Coloration varies from olive-green to reddish-brown with pale spots; sexual dimorphism is evident in abdomen shape, a trait referenced in comparative morphology studies at universities including University of Cambridge and University of Oxford.

Distribution and Habitat

Native distribution spans the northeastern Atlantic Ocean from Bergen and the North Sea coasts to Morocco and the Mediterranean Sea. Introduced ranges include the east and west coasts of North America, the west coast of South America, southern Africa, Australia, and parts of Asia such as Japan. Habitats occupied include rocky intertidal zones, mudflats in estuaries like the Chesapeake Bay, and vegetated saltmarshes such as those found in San Francisco Bay. Shipping routes tied to ports including Rotterdam, New York Harbor, Sydney Harbour, and Valparaíso have been implicated in transport via ballast water and hull fouling in reports by agencies like the International Maritime Organization.

Ecology and Life History

Feeding ecology is opportunistic; diets documented in field studies from the Gulf of Maine and Bay of Fundy include bivalves such as Mytilus edulis and Mercenaria mercenaria, gastropods, polychaetes, and small crustaceans. Predation pressure varies with native predators including European green crab's shared predators like European cod in native waters and Dungeness crab and American lobster in invaded regions, though alternative prey dynamics have been observed in estuaries such as Puget Sound. Reproductive cycles are linked to sea surface temperature regimes monitored by institutions like National Oceanic and Atmospheric Administration and CSIRO; females can produce multiple broods per year with planktotrophic larvae dispersing in coastal currents influenced by systems such as the Gulf Stream and the California Current.

Invasive Spread and Impacts

Introductions have caused measurable declines in commercially important shellfish stocks in regions associated with fisheries authorities like the National Oceanic and Atmospheric Administration Fisheries and the Department of Fisheries and Oceans (Canada). Impacts include predation on native bivalves in the Gulf of St. Lawrence, alteration of saltmarsh plant communities in the Wadden Sea and Delaware Bay, and competition with native crab species recorded by regional agencies including the California Department of Fish and Wildlife and the Marine Management Organisation (UK). Economic assessments by entities such as the World Bank-linked studies and regional governments have highlighted costs to aquaculture operations in areas managed by companies regulated under laws like the Magnuson-Stevens Fishery Conservation and Management Act.

Management and Control

Management strategies range from mechanical removal programs coordinated by local conservation groups and agencies such as NOAA and the Canadian Department of Fisheries and Oceans to policy measures addressing ballast water under the International Maritime Organization's Ballast Water Management Convention. Experimental biocontrol research has engaged institutions such as Cornell University and University of California, Davis to evaluate targeted trapping, pheromone lures, and novel exclusion techniques used in hatcheries overseen by agencies like the National Marine Fisheries Service. Restoration of native predators and habitat recovery projects have been implemented in collaboration with organizations including The Nature Conservancy and governmental bodies like the Environment Agency (England).

Research and Monitoring Methods

Monitoring employs standardized protocols developed by consortia including the Global Invasive Species Programme and regional networks coordinated by the North Pacific Marine Science Organization and the Atlantic Cooperative on Invasive Species. Methods include intertidal quadrat surveys used by universities such as Dalhousie University and University of Washington, genetic population analyses performed in laboratories at institutions like University of British Columbia and the Scripps Institution of Oceanography, and larval sampling tied to oceanographic programs run by NOAA and CSIRO. Citizen science initiatives coordinated with NGOs such as iNaturalist and the Audubon Society complement formal monitoring and have contributed occurrence records used in models by research centers like the Pew Charitable Trusts.

Category:Invasive crustaceans