Photosynthetic production and irradiance-photosynthesis relationships of the phytoplankton from a shallow equatorial lake (Lake George, Uganda).

The photosynthesis-irradiance characteristics of the phytoplankton of the shallow but optically deep Lake George, Uganda, are discussed in relation to established models of integral photosynthetic production. The horizontal and diurnal variation of photosynthetic capacity (P max), and of other photosynthesis-irradiance characteristics, prevents an accurate estimate of photosynthetic production in Lake George. The diurnal studies showed that P max fell as light-saturation onset (I k ) values increased which, coupled with the reduction of chlorophyll a concentration within the euphotic zone, causes an asymmetrical distribution of daily photosynthetic production about mid-day.