Coleopteran diversity and abundance in different habitats near Kihansi waterfall, in the Udzungwa Mountains, Tanzania

Abstract

Coleoptera diversity at the family level was investigated along the Kihansi gorge near a 700 m high waterfall system which will be taken to hydropower use, and the current river flow will be diverted due to dam construction. The coleopteran communities of three micro-habitats: spray zone, forest site and riverine site were compared by sweepnetting and pitfall trap methods. The highest Coleopteran family level diversity was found in the spray zone where the Shannon-Weaver index of diversity was 0.71 (forest site 0.31; riverine site 0.50). Coleopterans were most abundant in the forest site where 44% of all sampled individuals were found (spray zone 31%; riverine site 23%). Most of less frequently recorded families were found in the spray zone. Coleoptera families were found to be unequally partitioned in all three micro-habitats. The highest percentage similarity index (85%) was found between forest and riverine sites (spray/forest 76%; spray/riverine 79%). Distributions of abundances of coleopteran families were significantly different between all studied habitats. The study revealed that the spray generated by the waterfall provide a special micro-habitat for Coleoptera. It is suggested that conservation efforts and monitoring in the study area using selected taxonomic indicator Coleopteran groups should be carried out in order to help to adjust mitigation measures.