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Magnitude and Extent of Sediment Toxicity in Four Bays of the Florida Panhandle: Pensacola, Choctawhatchee, St. Andrew and Apalachicola

The toxicity of sediments in Pensacola, Choctawhatchee, St. Andrew and Apalachicola bays and Bayou Chico was determined as part of a bioeffects assessment.

The objectives of the survey were to determine:

  1. the spatial patterns in toxicity throughout each bay;
  2. the spatial extent of toxicity throughout and among the bays;
  3. the severity or degree of toxicity; and
  4. the relationships between chemical contamination and toxicity.

The surveys were conducted over two years: Pensacola Bay and St. Andrew Bay were sampled in 1993; and Choctawhatchee Bay, Apalachicola Bay and Bayou Chico were sampled during 1994.

Surficial sediment samples were collected from 123 randomly-chosen locations throughout the five areas. Toxicological tests were conducted to determine survival, reproductive success, morphological development, metabolic activity, and genotoxicity. All bays showed toxicity in at least some of the samples. Toxicity was most severe in Bayou Chico, an industrialized basin adjoining Pensacola Bay . Other developed bayous, adjoining Pensacola Bay and the other bays, also showed relatively severe toxicity. The different toxicity tests, however, indicated differences in severity, incidence, spatial patterns, and spatial extent in toxicity. The most sensitive test, a bioassay of metabolic activity of bioluminescent bacteria, indicated toxicity was pervasive throughout the entire study area. The least sensitive test, an acute bioassay performed with a benthic amphipod, indicated toxicity was restricted to a very small portion of the area.