Cumulative impacts of future climate conditions and heavy fuel oil on corals By Mikaela Nordborg James Cook University/AIMS
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oral reef health and resilience are affected by both global (e.g. climate change) and local stressors such as oil pollution. As the impacts of climate change on coral reef ecosystems continue to increase1 management and risk assessments relating to reef environments will have to account for the potential interactions between local stressors and climate change. Oil pollution remains a substantial threat to reef environments due to its interactions with environmental factors in reef
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REEF IN REVIEW
environments (e.g. ultraviolet light; UV)2, the often long recovery times following spill events3 and the projected future increases in shipping in reef areas of high importance (e.g. the Great Barrier Reef region)4. The phototoxicity of petroleum oils (i.e. an increase in toxicity in the presence of UV light) is well documented5 and illustrates the potential for cumulative impacts between oil pollution and environmental stressors. Increasing water temperature due to climate change may also affect the toxicity of petroleum oils but this remains largely untested. For reef-associated organisms, sensitivity to oil exposure has been most extensively studied in reefbuilding corals (Nordborg et al. in prep.). However, the vast majority of studies have not accounted for potential interactions with environmental factors, such as UV or increasing temperature, and no studies have combined all three stressors (Nordborg et al. in prep.). While methodological
differences generally prevent direct comparisons between studies it appears that larval settlement and survival may be among the most sensitive endpoints for coral6.
“The vast majority of studies have not accounted for potential interactions with environmental factors.� Additionally, many broadcast spawning coral larvae spend a substantial amount of time at or near the surface during early development where exposure to both oil and UV can be expected to be highest. Therefore, to investigate the potential interactions between heavy fuel oil toxicity, UV and high temperature (marine heatwave conditions and projected future increases), chronic exposures of Acropora millepora larvae were performed in the National Sea
