Meeting Abstract

P3.105  Jan. 6  Influence of water quality on immune function in the Eastern oyster, Crassostrea virginica MACEY, B.M.**; MILLER, T.E.; WILLIAMS, H.; RATHBURN, C.K.; BURNETT, L.E.; BURNETT, K.G.; College of Charleston, SC maceyb@cofc.edu

Variation in water quality, due to natural and anthropogenic factors, may alter the ability of marine organisms to defend themselves against pathogens. We have developed a bacterial clearance assay to assess overall immune function of the oyster Crassostrea virginica. This assay quantifies the ability of oysters to inactivate and degrade the bacterium Vibrio campbellii injected into adductor muscle. In laboratory experiments, we have used this assay to show that exposing oysters to hypercapnic hypoxia (2% CO₂, 19-20% air-saturation, pH 6.2-6.5) for 4 h significantly reduces their ability to inactivate bacteria. After 60 min 18% (SEM=2, n=10) of injected Vibrio could be cultured from the tissues of oysters exposed to normoxia (98% air-saturation, pH 7.8-8.0), while 36% could still be cultured from hypoxic oysters (SEM=7.5, n=7). In field experiments, we have used this assay to assess overall immune function of oysters collected from tidal creeks with different contaminant loads. Bacterial clearance and total hemocyte counts were determined in oysters within 3 days after field collection. There was a strong negative correlation (r=0.893, p<0.001) between the total hemocyte counts and the ability of oysters to inactivate bacteria. Preliminary analysis of field data also indicates that oysters from less contaminated sites clear bacteria more rapidly than those from highly contaminated sites. We suggest that poor water quality can increase the risk that oysters will harbor and transmit bacterial pathogens hazardous to human and ecosystem health. (Supported by the OHH Center of Excellence at the Hollings Marine Laboratory).