Invasion
Invasion Description
1st Record: Milford/CT/Long Island Sound (1993, McDermott 1998)
Geographic Extent
Bronx/NY/Pelham Bay (1994, McDermott 1998); Rye/NY/Long Island Sound (1994, Kraemer et al. 2007); Milford/CT/Long Island Sound (1993, McDermott 1998); East Haven/CT/Long Island Sound (1995, USGS Nonindigenous Aquatic Species Program 2008); Millstone (Waterford)/CT/Long Island Sound (1995, USGS Nonindigenous Aquatic Species Program 2008); Groton/CT/Long Island Sound (2015, Lord and Williams 2016, 41.3170 -72.0616); Crane Point, Long Island/NY/Long Island Sound (1997, Gerard et al. 1999)
Vectors
Level | Vector |
---|---|
Alternate | Ballast Water |
Alternate | Hull Fouling |
Alternate | Natural Dispersal |
Regional Impacts
Ecological Impact | Predation | |
Field and experimental studies support the occurrence of strong impacts of Hemigrapsus sanguineus predation on small shore fauna (mussels, snails, etc.), and juvenile crabs, paticularly Carcinus maenas. Enclosure studies in Long Island Sound found a measurable effect of H. sanguineus on recruitment of barnacles during larval settlement, but this effect was short-lived (Brousseau and Goldberg 2007). The replacement of C. maenas by H. sanguineus in rocky intertidal regions of southern New England waters (Long Island to Cape Ann) has resulted in a likely increase in predation rates, due to higher population densities of H. sanguineus (Lohrer and Whitlach 2002a; Griffen and Delaney 2007). In an 8-year field survey in Rye, New York, by 2005 L. littorea had declined to 25% of its 1998 density, and was negatively correlated with the abundance of H. sanguineus (Kraemer et al. 2005). Enclosure experiments at Black Rock Harbor, Connecticut, indicated that H. sanguineus predation accounted for up to 25% of mortality of Blue Mussels (Mytilus edulis (Brousseau et al. 2014). Field sampling at Crane Pt., New York, in 1997-1998 indicated that H. sanguineus outnumbered C. maenas by ~100 to 1 at sites where juvenile C. maenas had been formerly abundant in intertidal rocky habitats (Gerard et al. 1999). Similar declines, to 10-20% of initial abundance, and a scarcity or absence of small juvenile C. maenas were seen at New Haven and Millstone Point, Connecticut (Lohrer and Whitlatch 2002b). A survey of crab abundance at Rye, New York, from 1998 to 2005, found that C. maenas was only 1% of the crab population in 1998, and was not seen at all after 2000. Eurypanopeus depressus went from 45% of the population to 0%, and in 2005, H. sanguineus comprised 100% of the intertidal crabs (Kraemer et al. 2007). Field enclosure experiments indicated that predation by adult H. sanguineus on juvenile C. maenas was a major cause for the decline in the Green Crab population (Lohrer and Whitlatch 2002b). In a study of Littorina saxatilis (Rough Periwinkle, native) from 3 populations near Stony Brook NY, one population showed morphogical responses in shellll proportions to H. sanguineus, while two populations did not.repond. None of the populations showed shell growth reponses to the native Dyspanopeus sayi (Hooks and Padilla 2020). | ||
Ecological Impact | Competition | |
Field observations indicate that Hemigrapsus sanguineus has largely displaced Carcinus maenas from rocky intertidal habitats in Long Island Sound (Gerard et al. 1999; Jensen et al. 2002; Lohrer and Whitlatch 2002b; Kraemer et al. 2007). The native Dyspanopeus sayi (Say's Mud Crab) and Eurypanopeus depressus have also declined sharply from intertidal habitats in Long Island Sound, although they remain abundant in subtidal waters (Gerard et al. 1999; Kraemer et al. 2007). In comparison with Panopeus herbstii, the native Black-Fingered Mud Crab), in Long Island Sound, H. sanguineus had higher fecundity, multiple broods, a longer reproductive season, and more rapid dispersal (Brousseau and McSweeney 2016). | ||