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Correlation of measures of ambient toxicity and fish community diversity in Chesapeake Bay, USA, tributaries-urbanizing watersheds
| Author: |
Hartwell, S.Ian; Dawson, Celia E.; Durell, Eric Q. [and others] |
| Date: |
1997 |
| Periodical: |
Environmental Toxicology and Chemistry |
| Abstract: |
This study was performed to evaluate ambient toxicity conditions in Chesapeake Bay tidal tributaries whose watersheds are impacted by urban development and to further evaluate an existing toxicological risk ranking model. A battery of water-column and sediment bioassays were employed with animals and plants. The study was conducted in coordination with a fish community sampling program. Tests were conducted monthly from April through August 1994 at five sample sites in each of four tidal tributaries. Mortality, reproduction, and growth rates in the water-column assays did not consistently indicate chemical contamination in any system. Chemical analyses did not indicate elevated levels of contaminants in the water column. Sediment bioassays demonstrated greater responses than water-column assays. Sediment in the upstream reaches of the South River demonstrated significant toxicity. Toxicity was also observed at the uppermost Severn River station and the middle Patuxent River station. Chemical analyses of composite sediment samples indicated elevated metals levels in the South River. Some metals were above threshold values in the Patuxent and Wicomico rivers. The AVS/SEM ratios in pore water were below I in all cases. Organic analyses demonstrated low level polycyclicaromatic hydrocarbon contamination in all four systems. The toxicological risk ranking model ranked the South River as the most contaminant-impacted site. The Patuxent and Severn rivers were ranked below the South River; however, the ranking model identified specific locations in the Severn and Patuxent rivers that indicate sediment contamination. The Wicomico River had the lowest overall risk score. The Patuxent River requires more intense sampling due to its relatively larger size. The toxicological risk ranking results for sediment were significantly correlated with species diversity for fish communities sampled by bottom trawl. Results were consistent with data from previous years. Regression analysis of 2 years of data indicate that fish community impairment can be predicted with ambient toxicity results. |
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