Partitioning of underwater direct and diffuse ultraviolet irradiance in a shallow water coral reef

Veal, Cameron J., Michael, Kelvin J. and Nunez, Manuel (2009) Partitioning of underwater direct and diffuse ultraviolet irradiance in a shallow water coral reef. Marine and Freshwater Research, 60 12: 1244-1253. doi:10.1071/MF08318


Author Veal, Cameron J.
Michael, Kelvin J.
Nunez, Manuel
Title Partitioning of underwater direct and diffuse ultraviolet irradiance in a shallow water coral reef
Journal name Marine and Freshwater Research   Check publisher's open access policy
ISSN 1323-1650
Publication date 2009
Sub-type Article (original research)
DOI 10.1071/MF08318
Volume 60
Issue 12
Start page 1244
End page 1253
Total pages 10
Place of publication Austraila
Publisher CSIRO Publishing
Language eng
Abstract In optically shallow waters of coral reefs, the contribution of both direct and diffuse ultraviolet irradiance is poorly documented yet its involvement in biological processes is highly significant. Here we present a new approach of partitioning the ultraviolet attenuation coefficient into direct and diffuse components in the top 5 m of waters surrounding Heron Reef, Queensland, Australia (23°27′S, 151°55′E), during the austral summer solstice from 11 to 21 December 2005. A commercial ultraviolet radiometer, which operated in selected spectral bands centred at 305, 313, 320, 340, 380 and 395 nm, was fitted with an aquatic shadow-band that allowed the measurement of both global and diffuse irradiances. Direct irradiance was estimated by subtracting diffuse irradiance from global irradiance. Results revealed that direct irradiance was attenuated more quickly than diffuse irradiance, with stronger attenuation in the shorter wavelengths. Attenuation coefficients for the global, diffuse and direct components of irradiance were significantly different, justifying their separate treatment through partitioning. A significant dependence on turbidity explained more than 70% of the variation in attenuation of ultraviolet irradiance at the shorter wavelengths. The direct ultraviolet irradiance can exceed 50% of the global ultraviolet irradiance in shallow waters (05 m), a significant result that is generally overlooked in optical and biological studies.
Keyword Great Barrier Reef
Heron Island
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collection: Centre for Marine Studies Publications
 
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Created: Sun, 10 Jan 2010, 00:03:40 EST