The zoobenthic fauna of the Nhlabane coastal lake system, KwaZulu-Natal, South Africa, 20 years after construction of a barrage

Abstract

The zoobenthos of the Nhlabane coastal lake system in northern KwaZulu-Natal was sampled quarterly during 1992 in order to study the zoobenthic fauna of the Nhlabane lake and estuary. The ecology of the system was changed in 1977 when a barrage was constructed across the upper end of the estuary. Physico-chemical parameters revealed that the previously estuarine southern basin of the lake had become completely fresh. The estuary remained closed during the study period due to a drought, the presence of the barrage and water abstraction from the lake. Benthic composition of the lake was typical of a shallow subtropical coastal lake, comprising a dominant estuarine associated crustacean component and a typical freshwater component characterised by oligochaetes, insect larvae and molluscs. Benthic densities varied with sediment type, with highest densities in detrital mud. The benthic composition of the estuary, dominated by estuarine amphipods and polychaetes, differed from that of the lake.

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