Science Diliman, Vol 18, No 1 (2006)

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Development Of A Simple Biological Model Of Vertical Phytoplankton Distribution

Karlo Primavera, Maria Lourdes San Diego-McGlone, Cesar Villanoy

Abstract


Phytoplankton in tropical waters aggregate and form a maxima below the surface where the common limiting materials for growth (light from the surface, nutrients from the depths) are at optimal levels. The location of optimum growth conditions is dependent on various physical, chemical and biological factors. The formation of phytoplankton maxima was simulated through a coupled physical and biological model for vertical chlorophyll distribution in Philippine waters. This paper evaluates biological models and the significance of 1) different forms of phytoplankton response to irradiance and nutrient uptake, 2) rate of nutrient uptake, and 3) light and/or nutrient limitation determining nutrient uptake. Phytoplankton response-to-irradiance form is less important than rate of light extinction in affecting the deep chlorophyll maximum (DCM) depth. The Michaelis-Menten form of nutrient uptake gives a bigger and deeper DCM but only under certain conditions. Temperature does not significantly affect nutrient uptake gives bigger and deeper DCMs. These findings will come in handy in future work of simulating empirical chlorophyll profiles.

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