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Tampa Bay Bioeffects
The objectives of the survey in Tampa Bay were to determine the spatial patterns and scales of toxicity, determine the severity and degree of toxicity, and identify the relationships between chemical contamination and toxicity.
The survey was conducted in two phases: 90 samples were collected in 1991; and 75 additional samples were collected in 1992. Three independent toxicity tests were performed, including: a 10-day amphipod survival test in using Ampelisca abdita; a 1-hour sea urchin egg fertilization test of pore water with Arbacia punctulata; and a 5-minute Microtox™ bioluminescence test with solvent extracts of the sediments. The concentrations of trace metals, polynuclear aromatic hydrocarbons (PAHs), and chlorinated organic compounds were also quantified.
Of the 165 undiluted sediment pore water samples that were tested with respect to urchin egg fertilization, 79% were significantly toxic relative to controls. In contrast, only 6% of the 165 samples were toxic in the amphipod tests.
In the Microtox™ tests, 27% of the 90 samples tested were significantly toxic. Overall, toxicity was most severe in northern Hillsborough Bay .
Also, relatively high toxicity was found in portions of Cross Bayou Canal, Bayboro Harbor, western Old Tampa Bay, St. Petersburg yacht basins, lower Boca Ciega Bay, and Bear Creek. Toxicity was least severe in Safety Harbor, central and eastern Old Tampa Bay, lower Tampa Bay, Big Bayou, Little Bayou, and Bayou Grande.
The sea urchin test was highly sensitive to the undiluted pore water samples, indicating that approximately 464 km2 were significantly toxic.
Collectively, the amphipod survival test, the Microtox™ bioluminescence test, and the sea urchin tests performed with the most diluted concentration of pore water tested (25%) indicated that about 0.5-0.6 km2 of this area was highly toxic. Concentrations of trace metals, pesticides, polychlorinated biphenyls (PCBs) congeners, PAHs, and ammonia were highly correlated with the measures of toxicity. Also, the concentrations of many substances, especially total DDTs, endrin, total PCBs, certain PAHs, lead, and zinc, occurred at concentrations in the toxic samples that equaled or exceeded concentrations that had been previously associated with toxicity.
Project Partners
Tampa Bay National Estuary Program