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Diurnal variability in turbidity and coral fluorescence on a fringing reef flat: Southern Molokai, Hawaii

January 1, 2008

Terrigenous sediment in the nearshore environment can pose both acute and chronic stresses to coral reefs. The reef flat off southern Molokai, Hawaii, typically experiences daily turbidity events, in which trade winds and tides combine to resuspend terrigenous sediment and transport it alongshore. These chronic turbidity events could play a role in restricting coral distribution on the reef flat by reducing the light available for photosynthesis. This study describes the effects of these turbidity events on the Hawaiian reef coral Montipora capitata using in situ diurnal measurements of turbidity, light levels, and chlorophyll fluorescence yield via pulse-amplitude-modulated (PAM) fluorometry. Average surface irradiance was similar in the morning and the afternoon, while increased afternoon turbidity resulted in lower subsurface irradiance, higher fluorescence yield (??F/Fm???), and lower relative electron transport rates (rETR). Model calculations based on observed light extinction coeffecients suggest that in the absence of turbidity events, afternoon subsurface irradiances would be 1.43 times higher than observed, resulting in rETR for M. capitata that are 1.40 times higher.

Citation Information

Publication Year 2008
Title Diurnal variability in turbidity and coral fluorescence on a fringing reef flat: Southern Molokai, Hawaii
DOI 10.1016/j.ecss.2007.08.023
Authors G.A. Piniak, C. D. Storlazzi
Publication Type Article
Publication Subtype Journal Article
Series Title Estuarine, Coastal and Shelf Science
Series Number
Index ID 70033469
Record Source USGS Publications Warehouse
USGS Organization