EFFECTS OF DESICCATION PRACTICS ON Vibrio ABUNDANCES OF CULTURED OYSTERS, Crassostrea virginica.
The expansion of off-bottom aquaculture to the Gulf of Mexico has raised concerns for human health officials. The higher temperatures found in the Gulf of Mexico are associated with increased concentrations of Vibrio vulnificus and Vibrio parahaemolyticus. These bacterial pathogens, found in shellfish, are known to cause gastroenteritis and septicemia in humans. Due to the limited research that has been done on the length of time desiccated oysters need for vibrio concentrations to return to background levels. Currently, inadequate information is available to guide regulations that adequately protect human health while minimizing the burden on oyster farmers.
This study evaluated the amount of time needed to return vibrio concentrations to background levels in oysters that have been exposed to the following desiccation practices: 3 hour freshwater dip followed by 24 hour ambient air exposure 27 hour ambient air exposure and control All oysters were submerged at least 3 weeks prior to the beginning of each trial with control samples remaining submerged during the duration of each trial. Samples were collected on day 0, 1, 2, 3, 7, 10, and 14 and immediately put on ice. Vibrio levels were enumerated using MPN enrichment followed by BAX® PCR.
Preliminary analysis suggests that V. vulnificus and V. parahaemolyticus levels in desiccated (Air) and freshwater dipped samples (H2O) are greater than control samples (Sub), prior to re-submergence. By 2 days post re-submergence vibrio levels appear similar across all treatments. The results of this study provide scientific support in identifying the minimum length of time oyster farmers should to submerge their oysters prior to ffinal harvest.