Phytoplankton biomass and production in the river Meuse (Belgium)

The biomass and production of the phytoplankton in a relatively unpolluted reach of the River Meuse (Belgium) were followed through two years (1983 and 1984). Chlorophyll a varied from 0. 2 to about 120 mg m** minus **3, and production ranged between 0. 05 and 5. 78 gC m** minus **2 d** minus **1. The mean photosynthetic quotient (PQ) was 1. 25. The parameters of the light-photosynthesis relationship (P//o//p//t and l//k) were calculated and related to the variations of temperature and light in the water column. A simple model allowed calculations of the annual production, which was estimated to be 494 gC m** minus **2 yr** minus **1 in 1983 and 547 gC m** minus **2 yr** minus =U 1 in 1984. Finally, a simple model is developed, which explains the relationship between phytoplankton development and discharge.