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Description:
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Vibrio vulnificus is a human pathogen commonly found in coastal and estuarine
waters in temperate and subtropical regions across the world . The ecology of V .
vulnificus has been studied in these regions primarily using cultured -based methods for
enumeration of V . vulnificus from the environment . Optimal temperature and salinity
ranges have been established , but relationships with other environmental parameters
have not been studied as extensively . The primary objective of this study was to better
understand the ecology of V . vulnificus and how environmental parameters found in
south Texas bays and estuaries regulate its distribution .
A recently developed molecular biological technique for the direct enumeration
of V . vulnificus from estuarine water column samples was used to test three hypotheses :
1 ) V . vulnificus makes up a greater percentage of the total bacterial population in the
water column under low oxygen conditions ; 2 ) Powderhorn Lake serves as a pointsource
for V . vulnificus in Matagorda Bay ; 3 ) Higher V . vulnificus concentrations are
found in the water column when oyster reefs are present . These hypotheses were formed
to improve predictive models , identify potential hot -spots for V . vulnificus in the water
column , and to better inform stakeholders as to when and where risk of infection might
be greatest .
Dissolved oxygen was rarely low enough in the environment to stress aerobic
bacteria in the water column , so the first hypothesis could not be appropriately tested .
Neither higher concentrations nor detection frequencies of V . vulnificus were found in
Powderhorn Lake compared to the rest of the bay , so Powderhorn Lake was not
identified as a point -source for V . vulnificus . Higher concentrations and detection
frequencies of V . vulnificus were not found at sites with oyster beds , so oyster beds cannot be used as indicators of higher concentrations of V . vulnificus in the water
column .
Interestingly , patchiness of V . vulnificus was observed temporally and spatially
throughout the sampling region of Matagorda Bay , on a scale that has not been
frequently examined . Variation occurred between samples in close proximity to one
another , as well as between sampling dates . This distribution exhibited a small scale
patchiness not frequently reported in past studies . |