ON THE REPLENISHMENT OF SOME PLANT NUTRIENTS DURING THE UPWELLING PERIOD ON THE EAST COAST OFF INDIA

Abstract

The replenishment of the plant nutrients which get depleted in the euphotic zone due to the active growth of phytoplankton may be brought about by the decaying and dissolving of organic matter. However, as the dead organisms sink through the water, only a small amount dissolves in the euphotic zone. The remainder dissolves at greater depths in the sea, where, in the absence of light, it cannot be utilized by plants, and a means of adequate replenishment of the upper layers is for this nutrient-rich deepwater to be displaced upwards, as in upwelling. An example of this type of replenishment occurs on the East Coast of India during the upwelling period (La Fond, 1955).