The annual flood regime as a regulatory mechanism for phytoplankton production in Kainji lake, Nigeria

Abstract

Phytoplankton production was measured ‘in situ’ in Kainji lake from December 1970 to September 1972 using the oxygen light and dark bottle technique. Seasonal variations in solar radiation, transparency, temperature, and composition of subsurface light were also measured. Oxygen production per unit area varied from 220 to 4500 mg O2 m−2 day−1, the maximum production rate from 95 to 400 mg O2 m−3 h−1. Seasonal mixing of lake water and river water of varying turbidity changed the optical properties of the lake water and consequently affected phytoplankton production. The annual flood pattern was found to be an important factor regulating phytoplankton production in the lake.