Original Articles

THE INTERRELATIONSHIPS BETWEEN THE BIOLOGICAL AND PHYSICO-CHEMICAL PARAMETERS IN THE WATER PHASE OF SESHEGO DAM, NORTHERN TRANSVAAL


Abstract

Seshego Dam, Lebowa, was investigated over a period of 15 months (1974 – 1975). The interrelationships between biological parameters such as Biological Growth Potential (BGP), anaerobic fecal and coliform bacteria, Cladocera and Copepoda were established by means of factor and cluster analyses. Cladocera production is lower than Copepoda production. Parameters which may play a role in Cladocera production are: dissolved oxygen, BOD, PO4−P concentration and N/PO4−P ratios. Probable sources of nutrition for Cladocera are the phytoplankton (of which BGP may serve as an indication) and coliform bacteria. The production of the Copepoda is influenced by temperature, turbidity, conductivity, NO2−N, total nitrogen, SO4 and the N/PO4−P ratio. Food sources of the latter may be anaerobic bacteria and suspended particulate matter. The Cladocera and Copepoda do not appear to compete.

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