Yajnik, Kirit S., M.K. Sharada and P.S. Swathi

CSIR Centre for Mathematical Modelling and Computer Simulation, Wind Tunnel Road, Bangalore 560037, India, Tel: +91 (80) 227 6836, Fax: +91 (80) 227 9321, E-mail: ksy@postoffice.iisc.ernet.in

Uptake kinetics of phytoplankton in presence of nutrient interaction: lessons from JGOFS experiments in the Indian Ocean

Analysis of nitrogen dynamics experiments in the North Indian Ocean under JGOFS shows the properties of similarity and saturation of the inhibitory effect of ammonium on nitrate uptake. A general formulation will be presented for nutrient interaction relations on the basis of similarity and hyperbolicity and it will be applied to the ammonium-nitrate environment. The new relation will be shown to be more accurate than five relations proposed earlier. A new nonlinear least square method will be reported for the determination of the parameters of uptake kinetics. Implications on the f ratio will be discussed to bring out qualitative differences between the relations. The results of simulations of a 3D physical-biological model using different relations of ammonium-nitrogen interaction will be compared for the North Indian Ocean to point out the consequences of inaccuracies in the representation of kinetics of nutrient interaction.