Annual measurement of solar UVB at a reef site using a polyphenylene oxide dosimeter

Annual measurement of solar UVB at a reef site using a polyphenylene oxide dosimeter

Numerous investigations detailed over the last thirty years have highlighted how solar UV (290-400 nm) can have a detrimental effect on coral health. It has also been postulated that coral bleaching is caused by a synergistic process between high water temperatures and increases in UV. As a consequence of its influence upon coral ecosystems, UV radiation must be monitored in underwater locations using an appropriate non-invasive measurement technique in order to better understand the damage it causes on both a macro and micro scale and provide solutions on how to adequately manage its impact. The high energy UVB waveband (290-320 nm) is believed to have the greatest negative influence on coral stress. This report details the employment of a simple, easily deployable UVB measuring dosimeter system based on polyphenylene oxide (PPO) at a coral reef location near Hervey Bay (25°17 S, 152°52′ E) over the interval of one year. Continual deployment of the PPO dosimeters measured a clear inverse correlation between tide level and UVB penetration, with the highest coral UVB exposures measured during the months of winter and spring (coinciding with typically lower tidal conditions during this time). This suggests that the UVB incident on Queensland coral reefs may not be strictly dependent on solar zenith angle (the Sun’s position in the sky), which is generally the primary factor in determining the extent of terrestrial UVB exposures. Further, this may mean that photo-damage incident on corals could be exacerbated in traditionally cooler months if current global warming trends continue.

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