All ETDs from UAB

Advisory Committee Chair

Dale A Dickinson

Advisory Committee Members

Julia M Gohlke

Stephen A Watts

Document Type

Thesis

Date of Award

2014

Degree Name by School

Master of Science in Public Health (MSPH) School of Public Health

Abstract

To reduce possible ecological impact from oil spill events, the chemical dispersant Corexit 9500A is approved for widespread application. Concerns about toxic effects of dispersant on aquatic fauna have prompted numerous recent toxicological studies. Few of these studies have considered possible interactive effects involving Corexit exposure at normative or high temperatures associated with normal breeding seasons of many aquatic organisms. We examined development, survival, and hatch success of teleost model Danio rerio embryos exposed to Corexit while maintained at various temperatures. Calculated LC25, 50, and 75 values at 24 h Corexit exposure for 3 hpf embryos reared at the standard husbandry temperature of 28.5°C were 71.0, 110.4, and 171.7 ppm, respectively (Probit analysis, n=5 trials of 10 individuals each). Another cohort of 3hpf embryos was exposed to concentrations of Corexit (0, 80, 125, and 150 ppm for 24 h) at varying temperatures (24.7, 27.0, 29.5, and 31.7oC), representing higher thermal limits. Following exposure for 8 or 24 hrs, embryos were transferred into control media and observed at 27, 57 and 75 hpf. Exposure to higher Corexit concentrations and temperatures resulted in decreased survivorship compared to the lower concentrations and temperatures below 28.5°C, with the outcomes affected primarily during the exposure period. The incidence of phenotypic abnormalities increased with increasing Corexit concentrations and temperature. For embryos surviving the 24 h exposure, successful hatching started by 27 hpf for all Corexit concentrations at 31.7°C. A cohort of 57 hpf early larvae were exposed to concentrations of Corexit (0-200 ppm for 24 h). Hatched larvae showed a greatly reduced sensitivity to Corexit exposure (LC50 > 200 ppm) as compared to embryos. These data suggest that high temperature, as an environmental stressor, can exacerbate the effects of Corexit 9500A. Presuming other fish have similar sensitivities, it is possible that Corexit, particularly if applied in the summer when temperatures are elevated, could affect fish population demographics and, as a consequence, community structure.

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