Invasion
Invasion Description
1st Record: Point Judith/RI/ Block Island Sound (1994, McDermott 1998)
Geographic Extent
Weekapaug/RI/Block Island Sound (1997, Whitlach and Osman 2000); Point Jusith Pond Marina, Wakefield/RI/Point Judith Pond (2019, Pederson et al. 2019); Matunuck/RI/Block Island Sound (1997, Whitlatch and Osman 2000); Point Judith/RI/Block Island Sound (1994, McDermott 1998; 1997, Whitlatch and Osman 2000; Griffen and Delaney 2007); Block Island/RI/Block Island Sound (USGS Nonindigenous Aquatic Species Program 2008)
Vectors
| Level | Vector |
|---|---|
| Alternate | Ballast Water |
| Alternate | Hull Fouling |
| Alternate | Natural Dispersal |
Regional Impacts
| Ecological Impact | Predation | |
| Concomitant with a steady increase in the abundance of H. sanguineus, a decline in abundance of C. maenas (up 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 one site near Point Judith, 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, at a site near Point Judith (Griffen and Delaney 2007). | ||