CHANGES IN THE BENTHIC FAUNA OF LAKE CHIVERO, ZIMBABWE, OVER THIRTY YEARS

Abstract

Lake Chivero is a eutrophic Zimbabwean reservoir and data on its benthic fauna are available over a period of about thirty years. The levels of organic carbon are higher than in many other southern African reservoirs but have not increased since 1974. The numbers of chironomid larvae appeared to have decreased but this was a consequence of the very low level of the lake at the time of sampling. Other changes included a decrease in the number of mussels but a large increase in the population of prosobranch snails. This may be a consequence of both the lake's eutrophic state and a three-fold increase in calcium in the lake's water over the last twenty years.