TWENTY-FOURTH ANNUAL EASTERN FISH HEALTH WORKSHOP Royal Pavilion Resort, Atlantic Beach, NC MARCH 9-11, 1999 Susceptibility Of Shrimp To Vibrio parahaemolyticus Under Hypoxic Conditions Christina M. Mikulski1, L.E. Burnett1 and K.G. Burnett2 1Grice Marine Laboratory, University of Charleston, SC; 2Department of Microbiology and Immunology, Medical University of South Carolina, Charleston, SC Environmental conditions such as hypoxia suppress the production of reactive oxygen intermediates (ROIs) by phagocytes of invertebrate and vertebrate species, however, it is unclear that suppression of ROI production under hypoxic conditions will enhance susceptibility to infectious disease. We have developed a challenge model to test the importance of changes in water pH, CO2, and O2 on disease susceptibility in penaeid and palaemonid shrimp. Specific pathogen-free juvenile shrimp, Penaeus vannamei, were acquired from the Waddell Mariculture Center in Bluffton, South Carolina. Grass shrimp, Palaemonetes pugio, were collected from local tidal creeks in Charleston. Both species were acclimated to test conditions in the laboratory. Animals were injected intramuscularly with a previously determined LD50 dose of a known pathogenic strain of Vibrio parahaemolyticus. The shrimp were challenged under two levels of hypoxia (6% O2 saturation and 4% O2 saturation) in filtered artificial seawater kept at 30 ppt. Both the juvenile P. vannamei and the P. pugio held under 4% O2 (with 2% CO2 and pH of 6.8-6.9) displayed lower 48hr survival (15.7% and 3.1%, respectively) than animals held in well-aerated water (21% O2 saturation, pH of 7.7) (28.7% and 29.4%, respectively). Experiments are now underway to determine if the bactericidal activity of the shrimp hemocytes is equally susceptible to hypoxia. Supported by EPA Agreement R-826399. Return to 24th Annual Eastern Fish Health Workshop Return to Leetown Science Center Home Page