Meeting Abstract
The success of the invasive Asian shore crab, Hemigrapsus sanguineus, now commonly found along the rocky shores of the northwestern Atlantic and elsewhere, includes the ability to exclude other species from preferred rocky and cobble intertidal habitat. This study sought to test preference and competition for habitat types (cobble vs. sand) for H. sanguineus and two competitor species; the resident green crab, Carcinus maenas, and the native rock crab, Cancer irroratus. We paired similarly sized heterospecifics and conspecifics from each species, and also grouped combinations of C. maenas and H. sanguineus in sets of four, to test intra- and inter-specific competition at different densities. In individual controls, all three species significantly preferred cobble substrate. With paired conspecifics, both H. sanguineus individuals significantly preferred cobble, whereas Carcinus and Cancer individuals each excluded conspecifics from cobble. Similarly, H. sanguineus significantly excluded heterospecifics from cobble. In larger assemblages, H. sanguineus preferentially grouped under cobble, whereas C. maenas were more evenly distributed among habitat types. These patterns illustrate a clear mechanism for changes in distribution and habitat use among nearshore crab species following the introduction of Hemigrapsus in New England coastal systems.
