Reference: Biol. Bull. 181: 195-198. (August, 1991) A Breeding Population of the Western Pacific Crab Hemigrapsus sanguineus (Crustacea: Decapoda: Grapsidae) Established on the Atlantic Coast of North America JOHN J. McDERMOTT Department of Biology, Franklin and Marshall College. Lancaster, Pennsylvania 17604 The west Pacific grapsid crab Hemigrapsus sanguineus was found in the United States for the first time in 198S. Additional crabs were recovered in 1990 from Townsends Inlet and Cape May Harbor, New Jersey (22 males, 16 females), and four of the females collected from June through September were ovigerous. Thus, H. sanguineus has now established itself in southern New Jersey, the first well-documented case of an exotic brachyuran becoming established along the east coast of the United States. The marine grapsid crab Hemigrapsus sanguineus (de Haan, 1853), native to the western Pacific Ocean, was first recovered in the eastern United States in September 1988; a single ovigerous female was found in a rocky in-tertidal zone under a bridge at Townsends Inlet, Cape May County, New Jersey (1) (Fig. 1). The site was not reinvestigated until 20 months later (28 May 1990), and at that time an immature female H. sanguineus was re-covered [carapace width (CW) X carapace length (CL) = 12.8 X 10.8 mm]. This second finding suggested that the original record of the crab in New Jersey was not simply fortuitous, but that this Pacific brachyuran was established in Atlantic waters. The discovery also provided a rare opportunity to document a potentially major in-troduction. Subsequently, 36 additional mature and immature crabs (22 males and 14 females) (Fig. 2) were collected (26 June, 3 and 6 July, 22 August, 2 1 September, 1 5 and 28 October 1990) at the same site. Crabs were usually located in the mid to upper intertidal zone under rocks covered with Fucus vesiculosus, but at low tide some moved below the mid intertidal. As with many intertidal Received 15 November 1990; accepted 30 April 1991. grapsid crabs that live among rocks, individuals of H. sanguineus are secretive and swift, and one must turn rocks over rapidly and snatch them quickly in order to catch them; otherwise, they retreat among the lower in-accessible rocks. All crabs were transported to the Franklin and Marshall laboratory where they were easily main-tained individually in 2 cm of unaerated seawater (tem-perature 19C, salinity ~30%o); they subsisted on pieces of the macroscopic algae Enteromorpha sp. and Ulva lac-tuca. and otherwise required minimal care, except for a daily water change. Crabs were measured with a dial cal-ipers to the nearest 0.1 mm. The 22 males ranged from 8.3 to 24.1 mm CW (mean 17.2 4.6), and from 7.3 to 21.0 mm CL (mean 15.2 4.1); 15 females ranged from 3.6 to 24.4 mm CW (mean 17.6 5.1), and from 3.3 to 21.3 mm CL (mean 15.3 4.4). The greater range in females was due to one juvenile (3.6 mm), resulting from the 1990 spawning season, collected 15 October. The next smallest female was the 12.8 mm specimen collected 28 May; the smallest male (8.3 mm) was collected 26 June. These and other juveniles were probably from the 1989 spawning season. Ovigerous females (n == 4) were found from June through September (not in July collections). One oviger-ous crab, obtained on 26 June (CW X CL = 24.4 X 21.3 mm), carried embryos half filled with yolk but with no apparent pigment or eye development. The crab was pre-served three days later, and the embryos were counted (n = 28,702). Two ovigerous crabs (CW X CL = 1 5.2 X 1 3.2 mm, 23.2 X 19.8 mm) were collected on 22 August. The smaller of them released its zoeae (n = 6328) two days later, and on 27 August it had another brood. Although the crab aborted many undeveloped eggs from this brood. 195
A Breeding Population of the Western Pacific Crab Hemigrapsus sanguineus (Crustacea: Decapoda: Grapsidae) Established on the Atlantic Coast of North America
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