Limnology of reservoirs in the Southeastern part of São Paulo State, Brazil. VI. Primary Production.

Abstract

The phytoplankton primary production was measured at selected depths of the euphotic zone, in seventeen reservoirs of São Paulo State, by the "in situ" application of ¹⁴C technique. The study was carried out in quarterly samplings during 1979, in order to find the seasonal pattern. The studied reservoirs are located at different hydrographic basins and are submitted to a varied degree of human activity influence. The values of primary production ranged from 50.08 mgC.m^-2.day^-1 to 1,913.86 mgC.m^-2.day^-l (average values) allowing to differentiate reservoirs from low to high primary production levels. The results show that in most cases the production was higher in the hot period especially in November-December, and is probably related to the nutrients concentration. The variation along the year was best observed at the most productive reservoirs.