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Hollebone, A.L. and M.E. Hay, 2003. An Invasive Crab in the South Atlantic Bight: Friend or Foe? Georgia Institute of Technology. Proceedings of the Third International Conference on Marine Bioinvasions, La Jolla, California, March 16-19, 2003, p. 67. An Invasive Crab in the South Atlantic Bight: Friend or Foe?Biological invasions can threaten natural communities by altering the forces determining ecosystem structure and function. The green porcelain crab, Petrolisthes armatus, recently invaded oyster reefs of the South Atlantic Bight in densities of up to several thousand crabs/m2, but the effects of this invasion remain undetermined. Therefore, the focus of our research addresses the ecological implications of this invasion. In order to perform experiments relative to our concerns at the local, regional, and community-wide scales, we “recreated” oyster reefs in independently treated and replicated baskets within ten flow-through mesocosm tanks at the Skidaway Institute of Oceanography, Savannah, GA. The treatments included oysters from which all organisms were removed and combinations of locally dominant crab species at realistic densities. The combinations were: (1) no crabs, (2) mud crabs (Panopeus herbstii), (3) mean June density of porcelain crabs + mud crabs, and (4) 3x mean June density of porcelain crabs + mud crabs. These “communities” were maintained for several months. The sediments and growth on the oysters were monitored over time, and at completion all organisms were documented, assessed for growth and survivorship, physical and reproductive condition, and recruitment success. Preliminary data suggest that oyster settlement was more successful when there were no crabs and that mud crabs caused considerable damage to oysters and mussels when no porcelain crabs were available as an alternate food source. Contact: Amanda Hollebone, Skidaway Institute of Oceanography, Georgia
Institute of Technology, 10 Ocean Science Circle, Savannah, GA 31411, USA |