Crassostrea virginica
(the Eastern or American
oyster) bioaccumulates pollutants from the water column,
and therefore, its tissues can be used as bioindicators of
past and present estuarine health. In this pilot project, we
decided to investigate whether its tissues would be a suitable
medium for toxicity testing using tissues from a variety
of southern Texas locations of known and suspected
anthropogenically impacted and unimpacted areas. We also
conducted toxicity tests on sediments adjacent to oyster
reefs using standard protocols for sediment toxicity. We
tested the toxicity of tissues and sediments on the luminescent
bacteria
Vibrio fischeri
, whose bioassays are
commonly referred to by the trade name Microtox®. Microtox
tests are quick, relatively inexpensive and sensitive
to a range of contaminants. Evidence from this preliminary
study suggests that conducting toxicity tests on oyster tissues
may predict localized contamination better than when
conducting toxicity tests on subtidal sediment. The refinement
of these methods to use oyster tissues to detect
contamination may be especially useful for environmental
impact studies and/or studies where rapid and inexpensive
information is needed.