Sediment and Vegetation as Reservoirs of Vibrio vulnificus in the Tampa Bay Estuary and Gulf of Mexico

Abstract

ABSTRACTThe opportunistic pathogenVibrio vulnificusoccurs naturally in estuarine habitats and is readily cultured from water and oysters under warm conditions but infrequently at ambient conditions of <15°C. The presence ofV. vulnificusin other habitats, such as sediments and aquatic vegetation, has been explored much less frequently. This study investigated the ecology ofV. vulnificusin water by culture and quantitative PCR (qPCR) and in sediment, oysters, and aquatic vegetation by culture.V. vulnificussamples were taken from five sites around Tampa Bay, FL. Levels determined by qPCR and culture were significantly correlated (P= 0.0006;r= 0.352); however,V. vulnificuswas detected significantly more frequently by qPCR (85% of all samples) compared to culture (43%). CulturableV. vulnificusbacteria were recovered most frequently from oyster samples (70%), followed by vegetation and sediment (∼50%) and water (43%). Water temperature, which ranged from 18.5 to 33.4°C, was positively correlated withV. vulnificusconcentrations in all matrices but sediments. Salinity, which ranged from 1 to 35 ppt, was negatively correlated withV. vulnificuslevels in water and sediments but not in other matrices. Significant interaction effects between matrix and temperature support the hypothesis that temperature affectsV. vulnificusconcentrations differently in different matrices and that sediment habitats may serve as seasonal reservoirs forV. vulnificus.V. vulnificuslevels in vegetation have not been previously measured and reveal an additional habitat for this autochthonous estuarine bacterium.