Eutrophication process: alkaline phosphatase activity of microplankton in the moroccan mesotrophic reservoir (Allal El Fassi)
Bacterial and phytoplanktonic alkaline phosphatase activity (APA) was measured from march to December 1998 in the mesotrophic Allal El Fassi reservoir located in the semi-arid zone (Morocco). The total APA varied between 0.107-1.780 mmol PNP·L-1·h-1. In epilimnion, the bacterioplankton contributed significantly (> 60%) to total APA. In the meta and hypolimnion, the APA was predominantly algal (> 58%). No correlation between APA and orthophosphates indicate that the hydrolysis by this enzyme was not a significant process in recycling of phosphorus in Allal El Fassi reservoir. Consequently, the APA was not a valid test of phosphorus deficiency.