The effects of the pesticides atrazine and brodifacoum on two Hawaiian corals

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2022

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Coral reefs are threatened by the effects of multiple anthropogenic stressors, including land-based runoff of sediments and toxicants. My dissertation focuses on determining the sublethal effects of exposure to two pesticides on two common species of Hawaiian corals. Atrazine is a restricted use herbicide that is still frequently found in stream samples around the Hawaiian Islands. In Chapter 1, I present data demonstrating sublethal effects in the lobe coral Porites lobata after exposure to 1 ppb and 10 ppb atrazine, through increased expression of stress response proteins. In Chapter 2, I present results of a dose-response experiment confirming that exposure to increasing concentrations of atrazine depresses photosynthetic efficiency rapidly and reversibly in the algal symbionts of Porites lobata. Brodifacoum is commonly used to eradicate populations of invasive rodents. Data presented in the third chapter identifies decreased fertilization success and larval survival in Montipora capitata after exposure to high concentrations of cereal bait pellets, regardless of whether the pellets contained the active ingredient brodifacoum. In Chapter 4, I describe decreases in dissolved oxygen and pH in cereal bait pellet solutions. Upregulation of citrate metabolism was observed in Porites lobata corals exposed to the brodifacoum treated pellets. Increased expression of glutathione S-transferase, an enzyme associated with detoxification, was observed in coral exposed to both brodifacoum treated and inert pellet solutions. The herbicide atrazine and rodenticide brodifacoum had sublethal impacts on corals at multiple life stages. Efforts to prevent pesticide contamination of nearshore waters can reduce threats to coral health. Managers should increase the use of tools such as proteomics that assess sublethal indicators of stress in corals to inform management decisions and monitor the effectiveness of interventions while moving away from death as an indicator of stress on a reef.

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Biology, Zoology, atrazine, brodifacoum, ecotoxicology, Montipora capitata, Porites lobata, proteomics

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200 pages

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