In-situ measurements of solar exposure distribution on a coral reef: preliminary findings relating to reef aspect, water turbidity and dosimeter design
Thin film dosimeters have been used for the measurement of solar radiation since the 1970s. Their application includes personal exposure measurement and environmental exposure monitoring. Polyphenylene oxide (PPO) films have recently been developed for use in various underwater environments. These dosimeters are capable of measuring solar ultraviolet-B (UVB, 290 – 315 nm), which is a recognized physical stressor of corals when combined with elevated water temperatures occurring within the irregular structure of a coral reef. We present preliminary findings employing a newly developed PPO dosimeter clamp deployed upon reef building corals situated within turbid inshore waters of the Great Sandy Marine Park, Southern Queensland, Australia. UVB exposures measured over a 24 hour period during peak summer exposure conditions ranged from 12.11 kJ m-2 to 21.13 kJ m-2. This preliminary data showed a clear dependence on reef aspect with the highest exposures incident upon north facing (Southern Hemisphere) reef surfaces. We conclude that exposure stress to corals may still occur in shallow turbid water with UVB exposure being strongly associated with reef aspect
