CONSERVING DRAGONFLY (ODONATA) ASSEMBLAGES RELATIVE TO RIVER DYNAMICSIN AN AFRICAN SAVANNA GAME RESERVE

Adult male dragonflies were sampled from 42 sites on four variously di sturbed rivers and three reservoirs in Kruger National park,South Afri ca. Fifty-one species and 2671 individuals were recorded. Large flow f luctuations resulted in a high species turnover during sampling. Drago nfly species richness mostly conformed with th intermediate-disturbanc e hypothesis, with species richness high on the rivers with moderate d isturbance and low on the most disturbed ones. Ordination of dragonfly species data separated rivers into clear groups, indicating that the dragonfly assemblages reflected the distinct plant physiognomic and ph ysical environmental conditions of each river system. Species that wer e abundant on any particular river had biotope preferences that reflec ted the overall environmental conditions of that river. Aquatic macrop hytes, including two exotic invasive species,promoted dragonfly specie s richness. These species, however, were not rare or threatened. Highl y disturbed rivers were characterized by species that preferred highly exposed situations with broad environmental conditions. In contrast, long grass or shady trees were important for some species because they buffered larger-scale, unpredictable environmental changes. Biotic di sturbance was also important because trampling by buffalo reduced loca l species richness and composition. Dragonfly assemblages were highly visible and sensitive indicators of aspects of long-term environmental conditions of the water body. Management recommendations for dragonfl ies and other aquatic invertebrates include maintaining water and ripa rian biotope heterogeneity, maintaining constant flow rates and water levels, and allowing some macrophyte cover. A little natural and anthr opogenic disturbance encourages much greater species richness than mor e extreme disturbance. The Sabie River is a major subject for conserva tion action in the premier protected area of Kruger National Park.