The Effect of The Polycyclic Aromatic Hydrocarbon Naphthalene on Porites divaricata

Coral reefs are vital to marine ecosystems. Reefs provide a habitat for more than one million species of plants and animals, support lucrative fishing and tourism industries, and help to protect against beach erosion. Corals are threatened by a multitude of stress-inducing environmental factors, such as changes in temperature, salinity, pH, and pollutants in the water. Unfortunately, a frequent ocean pollutant is oil. Crude oil can exist in marine habitats naturally through petroleum seeps; however, the most detrimental effects of oil on reefs have been found to arise from the large, acute exposures caused from anthropogenic pollution events.

Research regarding the effects of oil pollution on coral health is limited, due to the fact that exposure methods are not standardized and therefore difficult to compare, and that each crude oil contains a varying composition of hydrocarbons. It has been previously recognized that the toxicity of a petroleum mixture results from the additive toxicities of its constituent hydrocarbons, so studying the effects of the individual hydrocarbons can be valuable in building a complex toxicity model that can be applied to any oil pollution event. The purpose of this study is to assess the effect of the hydrocarbon naphthalene on the coral Porites divaricata. This study also explores a novel passive dosing method, which allows for a consistent and steady concentration of naphthalene throughout experimentation.

The results of this study suggest the existence of a significant treatment effect of naphthalene on the coral, most prominently identified at concentrations of 8 ppm and 16 ppm. Coral health was assessed quantitatively using PAM (Pulse Amplitude Modulation) Fluorometry, and visually using both a condition score rubric and percent mortality analysis. The findings in this study could prove vital in predicting the toxicity of future oil pollution events, and ultimately serve to aid ecosystem biologists in mitigating the potential damage to reefs from future spills.