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Proceedings Paper

Relationship between near-surface chlorophyll and solar-stimulated fluorescence: biological effects
Author(s): John J. Cullen; Aurea M. Ciotti; Richard F. Davis; Patrick J. Neale
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Paper Abstract

The fluorescence of chlorophyll a (Chl) nm can be detected in water leaving radiance and related quantitatively to the concentration of Chl. Solar-induced fluorescence has also been related to photosynthesis in deeper waters. However, little is known about the relationships between Chl, fluorescence, photosynthesis, and irradiance near the sea surface. Quantum yields of fluorescence and photosynthesis, as well as the ratio of fluorescence to photosynthesis, change during exposures to bright light. Several physiological processes are at play. Consequently, it is difficult to construct models of near-surface quantum yields. Experimentation and comprehensive sampling in the field are required for critical information. Some approaches are presented here. Radiometer buoys that measure downwelling irradiance at 490 nm, Ed(490), and upwelling spectral radiance, Lu(lambda) are good tools for measuring solar-stimulated fluorescence during studies of near-surface biology. Results can be compared with experimental measurements using a fluorometer with a very weak measuring beam that does not perturb the balance between fluorescence and photosynthesis. Comparisons indicate that relationships between near-surface Chl, fluorescence, photosynthesis and irradiance can vary widely for reasons that are not yet well resolved. Still, Lu(683), corrected for backscatter and normalized to Ed(490), is a useful measure of near-surface Chl in many environments.

Paper Details

Date Published: 6 February 1997
PDF: 6 pages
Proc. SPIE 2963, Ocean Optics XIII, (6 February 1997); doi: 10.1117/12.266454
Show Author Affiliations
John J. Cullen, Dalhousie University (Canada)
Aurea M. Ciotti, Dalhousie University (Canada)
Richard F. Davis, Dalhousie University (Canada)
Patrick J. Neale, Smithsonian Environmental Research Center (United States)

Published in SPIE Proceedings Vol. 2963:
Ocean Optics XIII
Steven G. Ackleson; Robert J. Frouin, Editor(s)

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