Embargo Period

8-7-2025

Degree Name

MA in Climate Change and Global Sustainability

First Advisor

Jill Welter, PhD

Abstract

This study seeks to determine whether the level of human-impact, and in particular sunscreen use, influences the health of coral reefs on the island of Kauaʻi. Six paired sites in different regions of Kauaʻi were identified, each having a human-impacted site and an isolated counterpart site. By obtaining quantitative data on the coral reef at each site using 25-meter video transects, the overall health of the reef was assessed by measuring live coral cover, coral species abundance, prevalence of coral bleaching, and fish abundance. The level of human-impact in the form of number of people present and type of sunscreen used was obtained through structured interviews with beachgoers. One site (Nōmilu, isolated, West) was unable to be surveyed so two pairs of study sites were analyzed. There was no significant difference in the percentage of live coral cover between the human-impacted and isolated sites; there was significantly higher live coral cover at Anini (human-impacted, North) and Prince Kuhio (isolated, South) when compared with their counterpart paired study sites. Only at Prince Kuhio were sun protection choices fully reef-safe (defined as using mineral sunscreen or no sunscreen). All other sites had between 15% - 33% of beachgoers using sunscreen with banned chemical UV filters (oxybenzone and/or octinoxate). Residents of Kauaʻi not only chose reef-safe sun protection significantly more than visitors to the island but also tended to have stronger opinions on the use of reef-safe sunscreen in the Archipelago. The prevalence of visitors without knowledge of the harm their non reef-safe sun protection choices could cause to coral reefs is concerning and an issue which must be addressed. The correlations found in this study showing that there is both chemical sunscreen use and coral degradation at Anini as well as “reef-safe” sun protection use and healthier coral at Prince Kuhio shows that further research is needed to assess the level of damage to corals that chemical sunscreens are causing in Kauaʻi. It is recommended to continue this research with water sampling to determine concentration of UV filters in Kauaʻi’s waters It is also recommended to commence visitor education and sunscreen checkpoints at the Lihue airport to raise awareness of the harm chemical sunscreens with oxybenzone and/or octinoxate cause to coral reefs and decrease as much as possible the chemical sunscreens brought by visitors to the island.

Disciplines

Environmental Health and Protection | Environmental Sciences | Environmental Studies

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