Microbial flora of offshore relayed oysters, Crassostrea virginica, in Mobile Bay, Alabama

Oysters, Crassostrea virginica, were relayed from four acclimation sites with salinity and temperature ranges of 4.3 to 28 ppt and 26.5 to 38 degree C, respectively, to an offshore relay site with salinity and temperature ranges from 33 to 38 ppt and 24 to 30 degree C. This study was performed from July 22, 1996 through September 18, 1996. A total of three trials were performed in triplicate. These oyster groups were suspended at a depth of 6.5 m in mesh bags from a natural gas production platform. Oysters were primarily assayed for Vibrio vulnificus, fecal coliforms, Perkinsus marinus, and condition index at the end of each three week trial. Ten to twelve oysters collected during each trial were homogenized in a Waring blender for 1 to 2 min. Two hundred grams of homogenate was transferred to 200 g of phosphate buffered saline (w/w) followed by shaking. The resulting suspension was used for detection of V. vulnificus, fecal coliforms, and inoculated onto marine agar (MA) plates for total aerobic plate count. Oysters were sampled initially before being taken offshore and subsequently sampled for 3 weeks while at the relay site. This portion of the study looked at change in the microbial flora of oysters when taken to a different environment. Colonies were selected from MA plates and transferred to new MA plates to confirm isolation.