Phytoplankton productivity in relation to light intensity: A simple equation

Estuarine, Coastal and Shelf Science
By: , and 


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A simple exponential equation is used to describe photosynthetic rate as a function of light intensity for a variety of unicellular algae and higher plants where photosynthesis is proportional to (1-e-??1). The parameter ?? (=Ik-1) is derived by a simultaneous curve-fitting method, where I is incident quantum-flux density. The exponential equation is tested against a wide range of data and is found to adequately describe P vs. I curves. The errors associated with photosynthetic parameters are calculated. A simplified statistical model (Poisson) of photon capture provides a biophysical basis for the equation and for its ability to fit a range of light intensities. The exponential equation provides a non-subjective simultaneous curve fitting estimate for photosynthetic efficiency (a) which is less ambiguous than subjective methods: subjective methods assume that a linear region of the P vs. I curve is readily identifiable. Photosynthetic parameters ?? and a are used widely in aquatic studies to define photosynthesis at low quantum flux. These parameters are particularly important in estuarine environments where high suspended-material concentrations and high diffuse-light extinction coefficients are commonly encountered. ?? 1987.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Phytoplankton productivity in relation to light intensity: A simple equation
Series title Estuarine, Coastal and Shelf Science
Volume 24
Issue 6
Year Published 1987
Language English
Contributing office(s) San Francisco Bay-Delta, Pacific Regional Director's Office
Larger Work Type Article
Larger Work Subtype Journal Article
Larger Work Title Estuarine, Coastal and Shelf Science
First page 813
Last page 832
Online Only (Y/N) N
Additional Online Files (Y/N) N
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