HARTMAN, M.J.*; STANCYK, S.E.; LOHRER, A.M.; Univ. of South Carolina, Columbia; Univ. of South Carolina, Columbia; National Inst. for Water & Atmospheric Research, Hamilton, New Zealand: Native predators and the success of a newcomer, Petrolisthes armatus, the green porcelain crab to an oyster reef ecosystem in North Inlet, SC
Invasive species often experience large increases in population size after their arrival in a new locale. It has been postulated that this invasion success is due to a release from natural predators and/or parasites. Though this is often discussed in invasion ecology literature, it has rarely been experimentally tested. Petrolisthes armatus, the green porcelain crab, which is native to Brazil has been extending its range northward into the southeastern United States and has recently moved into South Carolina. P. armatus was first documented in North Inlet, SC located in the North Inlet-Winyah Bay National Estuarine Research Reserve in January of 1998 and by August of 2000 it had reached densities of > 200 individuals/m2 at several sampling sites. We directly tested the question of whether native predators influence the success of P. armatus in North Inlet by predator choice experiments in mesocosms in the laboratory in which the native xanthid crabs, Panopeus herbstii and Eurypanopeus depressus or the newcomer P. armatus were offered as prey to blue crabs, pinfish and toadfish. To mimic the changes in population density of P. armatus as it first entered North Inlet, the prey items of native xanthids to P. armatus were offered to the predators in the ratios of 4:1, 1:1, and 1:4. Preliminary analysis indicates that blue crabs preferentially prey upon the native species.
