Macroinvertebrates associated with two submerged macrophytes,Lagarosiphon ilicifolius and Vallisneria aethiopica, in the Sanyati Basin, Lake Kariba, Zimbabwe: effect of plant morphological complexity

摘要

Vallisneria aethiopica and Lagarosiphon ilicifolius are common and abundant submerged macrophytes in LakeKariba, Zimbabwe. The two species have distinct structural morphologies, with Vallisneria consisting of long ribbonlikeleaves, while Lagarosiphon has filiform stems with numerous small alternate leaves. This study investigatedthe effect of these architectural differences between the two plant species on their epiphytic macroinvertebrateassemblages in the shallow inshore waters of Lake Kariba. Ten sites were sampled on three occasions between Mayand July 2005. A total of 56 macroinvertebrate taxa was collected, 48 from Lagarosiphon and 45 from Vallisneria.Generally, the two plant species were associated with similar macroinvertebrate communities, but the averageabundances of most taxa, and thus the overall macroinvertebrate abundances, were significantly greater onLagarosiphon. The main macroinvertebrate functional feeding groups found on both plant species were collectorgatherers,grazers and predators, all of which were significantly more abundant on Lagarosiphon. Although themacroinvertebrate assemblages associated with Vallisneria and Lagarosiphon generally consisted of the same taxa,there were distinct and significant differences between them, probably due to the architectural differences betweenthe two submerged macrophytes.