Application of the Lake Habitat Survey method on the tropical Malilangwe reservoir, south-eastern lowveld, Zimbabwe

Abstract

The Lake Habitat Survey (LHS) method was developed to assess the ecological integrity of the physical habitat around lake and reservoir ecosystems, as well as to determine the magnitude of human pressure on lake systems. The LHS method has not previously been applied to tropical lakes but could potentially be a useful tool. The LHS approach was applied on a tropical African reservoir, Malilangwe reservoir, in 2011. The application of this methodology included the calculation of summary metrics Lake Habitat Metric Survey (LHMS) and Lake Habitat Quality Assessment (LHQA). Results show that although Malilangwe reservoir is experiencing increasing human pressure, it does not appear to suffer from a major invasion of alien plants. Its LHQA score, 76 out of 112, and LHMS score, 16 out of 42, are indicative of relatively few human pressures such as water pumping structures and residential areas. We conclude that the use of LHS can directly enhance the quality and reliability of hydromorphological assessments and can lead to better lake conservation and rehabilitation. It is clear that, for conservation management, a holistic assessment of naturalness, representativeness and species rarity needs to be made in conjunction with scoring systems.