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USGS · 70015311

Phytoplankton productivity in relation to light intensity: A simple equation

D. H. Peterson·M.J. Perry·K.E. Bencala·M.C. Talbot
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Abstract

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 −β1 ). The parameter β ( =I k −1 "> =I k −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 β 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.

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D. H. Peterson, M.J. Perry, K.E. Bencala, M.C. Talbot. 1987. Phytoplankton productivity in relation to light intensity: A simple equation. https://doi.org/10.1016/0272-7714(87)90154-5

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