Carcinus maenas Linnaeus, 1758

In Sweden, Carcinus maenas was observed to displace shrimp and other crabs from mussel flesh set out as bait (Eriksson et al. 1975b). C. maenas grows larger than the common existing shorecrabs in San Francisco Bay, and could compete vigorously for food with the native Hemigrapsus oregonensis, H. nudus and Pachygrapsus crassipes, and with the introduced Atlantic brackish-water crab Rhithropanopeus harrisii in the more saline part of R. harrisii' s range. Where abundant subtidally, C. maenas could compete with several Cancer species in the Bay. Competition is also possible with other benthic predators including invertebrates, fish and birds. Competition with H. oregonensis and R. harrisii for space under rocks on mudflats at low tide seems likely. (Cohen et al., 1995)

In United States Exclusive Economic Zone (EEZ) : It is a major predator of Mercenaria mercenaria (Quahog or Hard Clam) in southern New England (Walton et al. 2001). On the West Coast, Carcinus maenas is regarded as a potential predator on commercially important clams, including introduced Softshell Clams, Japanese Littlenecks (Venerupis philippinarum), and the Mediterranean Mussel (Mytilus galloprovincialis), as well as the native Pacific Littleneck (Leukoma staminea) (Grosholz et al. 2011); In Australian part of the Exclusive Econmic Zone (EEZ) : On the East and West coasts of North America, and in Australia Carcinus maenas has had serious impacts on shore communities; primarily as one of the chief predators of the intertidal zone. It can affect the survival and recruitment of gastropods, bivalves, other crabs, and probably a wide range of other invertebrates (Vermeij 1982a; Vermeij 1982b; Williams 1984; Grosholz and Ruiz 2002). Source: Fofonoff, P.W.; Ruiz, G.M.; Steves, B.; Carlton, J.T. (2014). National Exotic Marine and Estuarine Species Information System (NEMESIS) available online at http://invasions.si.edu/nemesis (WoRMS, acesso 02/06/2021)

C. maenas can degrade habitats. Its omnivorous diet can significantly impact the structure of intertidal and shallow subtidal communities (Cohen et al., 1995). Klassen and Locke (2007) suggest that C. maenas and other factors have decreased the abundance of eelgrass (Zostera marina) in the southern Gulf of St. Lawrence, Canada, but further studies are needed to better document and understand these interactions and impacts on the survivorship of Z. marina (Davis and Short, 1997; Davis et al., 1998) and degradation to other habitats. C. maenas is a voracious omnivore that will affect biodiversity, given that it feeds on species from at least 104 families, 158 genera in 5 plant and protist and 14 animal phyla, it could possibly cause extinctions, extirpations and reductions in abundance of native species (Cohen et al., 1995). (CABI, acesso em 02/06/2021)

C. maenas can degrade habitats. Its omnivorous diet can significantly impact the structure of intertidal and shallow subtidal communities (Cohen et al., 1995). Klassen and Locke (2007) suggest that C. maenas and other factors have decreased the abundance of eelgrass (Zostera marina) in the southern Gulf of St. Lawrence, Canada, but further studies are needed to better document and understand these interactions and impacts on the survivorship of Z. marina (Davis and Short, 1997; Davis et al., 1998) and degradation to other habitats. C. maenas is a voracious omnivore that will affect biodiversity, given that it feeds on species from at least 104 families, 158 genera in 5 plant and protist and 14 animal phyla, it could possibly cause extinctions, extirpations and reductions in abundance of native species (Cohen et al., 1995).

The green crab also carries a parasitic worm that can infect birds that prey on the crabs. This can have a potentially devastating effect by throwing off the food chain, and on the ecosystem as a whole in these areas. (Washington Sea 1998, Washington Dept.1997, Jaquette 1998, Holden 1997). (Tutt, 2000).

C. maenas is a voracious omnivore that will affect biodiversity, given that it feeds on species from at least 104 families, 158 genera in 5 plant and protist and 14 animal phyla, it could possibly cause extinctions, extirpations and reductions in abundance of native species (Cohen et al., 1995). (CABI, acesso em 02/06/2021)