Invasion
Invasion Description
1st Record: Narragansett/RI/Narrow River (Rhode Island Sound) (1994, McDermott 1998)
Geographic Extent
Narragansett/RI/Narrow River (Rhode Island Sound) (1994, McDermott 1998); Newport, Rhode Island Sound (1996, USGS Nonindigenous Aquatic Species Program 2008); Narragansett Bay Campus/RI/West Passage, Narragansett Bay (1997, Paul Fofonoff, personal observations); Cove Haven Marina, Barrington/RI/Narragansett Bay (2000, MIT Sea Grant 2002); Warwick Cove Marina, Warwick/RI/Narragansett Bay (2000, MIT Sea Grant 2002); Port Edgewood Marina, Cranston/RI/Providence River (2013, Wells et al. 2014); Savethe Bay Docks, Providence/RI/Providence River (2019, Pederson et al. 2021); Bristol/RI/Narragansett Bay (1998, O'Connor 2013); Fall River Battleship Cove, Fall River/MA/Taunton River (2000, MIT Sea Grant 2002)
Vectors
| Level | Vector |
|---|---|
| Alternate | Natural Dispersal |
| Alternate | Hull Fouling |
| Alternate | Ballast Water |
Regional Impacts
| Ecological Impact | Predation | |
| Concomitant with a steady increase in abundance of H. sanguineus, a decline in abundance of C. maenas (to 10-20% of initial abundance) and a scarcity or absence of small juveniles was seen at Point Judith in 1996-1999 (Lohrer and Whitlatch 2002).The replacement of C. maenas by H. sanguineus in rocky intertidal regions of Southern New England (Long Island to Cape Ann) has resulted in a likely increase in predation rates, due to much higher population densities of H. sanguineus (field survey results from Narragansett Bay, RI) (Griffen and Delaney 2007). | ||
| Ecological Impact | Competition | |
| Field sampling shows an overwhelming dominance of Hemigrapsus sanguineus over Carcinus maenas, both in numbers and biomass, in Narragansett Bay (Griffen and Delaney 2007). Hemigrapsus sanguineus, in experiments, accepted conspecific individuals in shelters, but excluded similarly sized Green Crabs (Carcinus maenas and native Rock Crabs (Cancer irroratus (Hobbs et al. 2017). Cobble beaches, in Narragansett Bay, stabilized by Saltmarsh Cordgrass Spartina alterniflora and Ribbed Mussels (Geukensia demissa) are dominated by H. sanguineus, while native mud crabs (mostly Eurypanopeus depressus). Hemigrapsus sanguineus has heavy successful recruitment in the cordgrass-mussel habitat, apperntly excluding mud crabs, and diffusing into the adjacent mud crab-dominated upper and lower cobble zones. Predation by mid crabs limits H. sanguineus in the 'pure' cobble zones (Altieri and Irving 2017). | ||