Defense Date

12-7-2022

Document Type

Thesis

Degree Type

Master of Science

Degree Name

Marine Science

First Advisor

Dr. D. Abigail Renegar

Second Advisor

Dr. Jose V. Lopez

Third Advisor

Dr. Nicholas R. Turner

Keywords

Atlantic staghorn coral, sunscreen, acute, toxicity, static renewal exposure assay

Abstract

Reports of the environmental effects of organic UV filters such as oxybenzone have led to the marketing of “reef-safe” sunscreen ingredients, including avobenzone and homosalate. Avobenzone provides broad-spectrum UV protection which blocks higher wavelength UV rays, the leading cause of aging and skin cancer. However, as polycyclic aromatic hydrocarbons (PAHs), organic UV filters have similar structures to crude oil and estrogens, some of which have been labeled endocrine disrupters. Common in personal care products, UV filters enter marine ecosystems via wastewater effluent and swimmers. Significant stress and mortality have been observed in juvenile and some adult scleractinian corals after exposure to several UV filters, leading to bans in some coastal regions. This study evaluated the individual effects of avobenzone and homosalate on the Atlantic staghorn coral Acropora cervicornis using 96 h assays in a static renewal exposure system. Acropora cervicornis exposed to avobenzone exhibited severe responses, including tissue attenuation, reduced growth rates, hypertrophied mucocytes, and mortality with an EC50 of 324.5 μg/L and an LC50 of 407.6 μg/L. Acropora cervicornis exposed to homosalate also showed tissue attenuation and hypertrophied mucocytes but to a lesser degree, with an EC10 of 629.9 μg/L. Avobenzone exhibited higher acute toxicity levels to adult coral than the previously banned organic UV filters, including oxybenzone and octinoxate. However, toxicity threshold concentrations were above the estimated solubility of each UV filter and quantified levels detected in coastal waters. Additional research is needed regarding chronic exposure to lower concentrations present in marine environments.

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