Nitrate - phosphate relationship in a tropical estuarine environment

379-381Relationship between NO3 -N and PO4 -P and seasonal variation of N:P in different zones of Vellar Estuary in relation to phytoplankton stock were analysed using the data collected during August 1970 to July 1972. Both the ratio of the concentration of the two nutrients (N:P) and the ratio of change in NO3 and PO4 (Δ N: Δ P) widely fluctuated due to monsoon floods and phytoplankton blooms during post monsoon and summer seasons. Relationship between N:P and the phytoplankton stock revealed some interesting facts as to the limiting nutrient in this shallow tropical estuary