Benthic Fauna and Sediments in the Newly Created Lake Kariba (Central Africa)

McLachlan, A. J.; McLachlan, S. M.

Benthic Fauna and Sediments in the Newly Created Lake Kariba (Central Africa)

1971

McLachlan, A. J. | McLachlan, S. M.

The development of bottom depostis and the distribution of the associated fauna were studied over a 2—year period in a drowned river "estuary" of the newly created Lake Kariba. The lake bottom was initially made up of submerged soil, the chemical characteristics of which could be related to the parent rock. However, the soil was found to be rapidly changing under the influence of shoreline erosion, river sediment, and the accumulation of organic debris. These factors also affected the distribution of bottom fauna, in which chironomid larvae predominated. Faunal biomass was positively correlated with the amount of organic carbon in the profundal zone and inversely associated with the quantity of coarse sand in the littoral. Superimposed on this pattern was a response to water depth. In the littoral zone, faunal biomass decreased with increasing depth. In the profundal region, benthos was absent when the lake was thermally stratified during the hot season. The annual regime of water—level fluctuation affected shoreline processes, for example by interrupting the development of barrier beaches and coastal erosion. Since these processes were fundamental to the development of sediment patterns, changes in water level influenced the distribution of bottom fauna as well.

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