THE WESTERN PACIFIC BRACHYURAN (HEMIGRAPSUS-SANGUINEUS, GRAPSIDAE), IN ITS NEW HABITAT ALONG THE ATLANTIC COAST OF THE UNITED-STATES - GEOGRAPHIC-DISTRIBUTION AND ECOLOGY

The Asian shore crab, Hemigrapsus sanguineus (de Haan, 1853), discover ed on the coast of New Jersey in 1988, is now known to be distributed in the western Atlantic from Massachusetts (south of Boston) to Oregon Inlet, North Carolina. Living in the mid to upper rocky intertidal zo ne, it exploits a niche mostly unoccupied by native brachyurans. In th e northern part of its range there is some mid-intertidal overlap with the green crab, Carcinus maenas. In North Carolina H. sanguineus beco mes sympatric in the high intertidal with another grapsid, the wharf c rab, Armases cinereum. Distributional evidence indicates that H. sangu ineus was probably introduced via ballast water at one or more major s hipping centres south of Cape Cod (i.e. the New York Eight, Delaware B ay, Chesapeake Bay), perhaps in the early 1980s. Its present latitudin al range in the western Atlantic is only about one-fifth of that in th e western Pacific. H. sanguineus is now the most abundant brachyuran a t the intertidal monitoring site in southern New Jersey, and apparentl y in some areas of Long Island Sound to the north. In New Jersey, crab s range in carapace width from 2.3 to 43.9 mm. The breeding season is from late April through September, and recruitment to the intertidal p opulation begins in June and continues through the fall and winter. So me crabs become subtidal, particularly during the winter months, as ev idenced by the growth of bryozoans, mussels and barnacles on their car apaces. There is no evidence in this population of parasitism with met acercariae, nemerteans, rhizocephalans or bopyrid and entoniscid isopo ds. (C) 1998 International Council for the Exploration of the Sea.