Original Articles

THE ENERGY BASE OF AQUATIC SYSTEMS IN SOUTH AFRICA

DOI: 10.1080/03779688.1982.9633236
Author(s): B.R. AllansonInstitute for Freshwater Studies, Department of Zoology, and Entomology, South Africa

Abstract

The energy base of reservoirs and lakes is examined. There is considerable variation in specific productivity and photosynthetic capacity depending on trophic condition and whether algae or suspensoids reduced transparency. While limnetic production is important in freshwater, it is not the only energy source, and eveidence is produced to show the relative contribution of littoral zones. In this regard Lake le Roux, Lake Sibaya and Swartvlei form a series in which the littoral becomes increasingly dominant in energy fixation. The littoral of Swartvlei provides 90% of total lake production. These autochthonous resources are compared with allochthonous inputs via rivers to reservoirs or lakes. The input to Lake le Roux via the Orange River provides 90% of the organic carbon input, whereas into Swartvlei, a natural coastal lake, the inflow provides only 7%.

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