The association between invertebrates and macrophytes in a tropical reservoir, Lake Kariba, Zimbabwe: a preliminary survey

Abstract

The invertebrate fauna associated with aquatic macrophytes in the littoral of Lake Kariba was studied over a three-month period in 2002. Animals from seven classes — Hirudinea, Oligochaeta, Turbellaria, Insecta, Crustacea, Bivalvia and Gastropoda — were collected. Two hirudineans, Placobdella sp. and Haemopsis sp., and a turbellarian, Dugesia sp., were the most abundant taxa in the shoreline zone where Eichhornia crassipes was the most important macrophyte. The invertebrate community on other macrophytes was very different from that on Eichhornia, being dominated by gastropods and the shrimp Caridina nilotica. This community was similar to that found on macrophytes in Lake Kariba between 1964 and 1976, although the diversity of taxa was generally lower. The density of invertebrates was about four times higher at depths >1m, but the reasons for this are not known although it may reflect the relative abundance of macrophytes or the effects of wave action.

Keywords: abundance; dominant organisms; Eichhornia crassipes; littoral zone; species composition; water depths

African Journal of Aquatic Science 2006, 31(2): 271–274