Development Of A Simple Biological Model Of Vertical Phytoplankton Distribution

Abstract

Phytoplankton in tropical waters aggregate and form a maxima below the surface where the commonlimiting 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 biologicalfactors. The formation of phytoplankton maxima was simulated through a coupled physical and biologicalmodel for vertical chlorophyll distribution in Philippine waters. This paper evaluates biological modelsand 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 thedeep chlorophyll maximum (DCM) depth. The Michaelis-Menten form of nutrient uptake gives a biggerand deeper DCM but only under certain conditions. Temperature does not significantly affect nutrientuptake gives bigger and deeper DCMs. These findings will come in handy in future work of simulatingempirical chlorophyll profiles.

Keywords

• Phytoplankton
• Philippine waters
• deep chlorophyll maximum