ECOLOGY OF VIBRIO-VULNIFICUS IN GALVESTON BAY OYSTERS, SUSPENDED PARTICULATE MATTER, SEDIMENT AND SEAWATER - DETECTION BY MONOCLONAL-ANTIBODY IMMUNOASSAY MOST PROBABLE NUMBER PROCEDURES

Oysters, suspended particulate matter (SPM), sediment and seawater samples were collected from West Galveston Bay, Texas over a 16-month period and analyzed for the presence of Vibrio vulnificus, a naturally-occurring human marine pathogen. Detection and enumeration of V. vulnificus was performed using a species-specific monoclonal antibody (mAb FRBT37) in an enzyme immunoassay (EIA)-most probable number (MPN) procedure capable of detecting as few as 2000 target organisms. V. vulnificus was not detected in seawater, oyster or SPM samples during the cold weather months, but was detected at low levels in several sediment samples during this time period. Increased levels of the organism were first observed in early spring in the sediment, and then in SPM and oysters. The major increase in V. vulnificus occurred only after the seawater temperature had increased above 20-degrees-C and the winter-spring rainfall had lowered the salinity below 16 parts per thousand. The highest V. vulnificus levels at each site were associated with suspended particulate matter. These results are consistent with the hypothesis that (1) V. vulnificus over-winters in a floc zone present at the sediment-water interface, (2) is resuspended into the water column in early spring following changes in climatic conditions, (3) colonizes the surfaces of zooplankton which are also blooming during early spring and (4) are ingested by oysters during their normal feeding process.