| An analysis of tropical upwelling systems shows a great range in the rate of increase of the standing stock expressed in terms of the water column chlorophyll content. Grazing appears to be the main factor responsible for lowering the rate of increase, especially in moderate and strong High Nutrient-Low Chlorophyll (HNLC) waters. A simple model comparing Net Community Production (NCP) rates with observed chlorophyll increase rates, leads us to conclude that phytoplankton population must present high specific growth rates on a daily rhythm in order to overcome grazing. Maximum specific growth rates (V(max)) calculated for daily total production (TP) are, in the two main upwelling areas, 137 d-1 off NW Africa and 1.04 d-1 off Peru. For extreme HNLC... |
