Chronic toxicity of pesticides to reef-building corals: Physiological, biochemical, cellular and developmental effects

Date of Award




Degree Name

Doctor of Philosophy (Ph.D.)


Marine Biology and Fisheries

First Committee Member

Peter W. Glynn - Committee Chair


This study examined the effects of long-term sublethal pesticide exposure to adult colonies and larvae of the scleractinian coral, Montastraea faveolata. The acute toxicity of chlordane to M. faveolata, another scleractinian coral, Porites divaricata, and a zooxanthellate tropical anemone were also examined. Corals were very tolerant of chlordane in short term tests (96 h LC50 P. divaricata = 15.3 mg/l; 96 h LC50 M. faveolata = 17.8 mg/l), but sensitive to long term exposures (sublethal effects were seen at concentrations as low as 1 $\mu$g/l). The anemone, Aiptasia pallida, was even more tolerant of short term chlordane exposure than the corals, and cannot serve as a model system for toxicity studies in corals. A 90 day exposure to 10 $\mu$g/l chlordane depressed photosynthesis, respiration, and P/R, caused bleaching by impacting algal densities and chlorophyll content, resulted in a significant induction of GST, and caused death for half of the exposed corals. Cytochrome P450 and EROD activity were not detected. This may explain the lack of metabolism of chlordane and long half life of the pesticide in this coral. The bioconcentration factor for chlordane in M. faveolata was lower than expected, and the pesticide was more concentrated in the coral tissue than in the alga. Histopathological examination revealed a proliferation of mucus secretory cells. Corals exposed to the pesticide produced large amounts of mucus, which may have caused the low bioconcentration factor by absorbing the pesticide before it could reach the coral tissue. Exposure to 10 $\mu$g/l also caused developmental abnormalities in larvae of M. faveolata.


Health Sciences, Toxicology; Biology, Oceanography; Environmental Sciences

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