Influence of physico-chemical parameters on benthic macroinvertebrate community dynamics in Isiukhu River, Kenya

Abstract

The current study investigated the influence of physico-chemical parameters on macroinvertebrates distribution, abundance and diversity throughout the Isiukhu River. The sampling sites were selected along the Isiukhu River based on distinct land use types at the upstream, midstream and downstream sections. Sampling was done twice monthly from March 2018 to March 2019. The DO and %DO saturation decreased downstream; and an increase in temperature, conductivity, turbidity, salinity, pH and ORP downstream. A total of (N = 993) macroinvertebrate individuals made up of 21 families were found. Veliidae, Gerridae, Notonectidae and Heptageniidae families dominated. The diversity and taxon richness declined from upstream to downstream. Senyende’s upstream site had the highest taxon richness (11.4) while Mutono’s downstream site had the lowest (1.4). The Kimangeti site upstream had a higher Shannon diversity index (2.2), whilst the Ekero site downstream had the lowest (1.2). A regression analysis showed that physico-chemical water quality parameters accounted for 54.8% of the spatial variability of macroinvertebrates. The study identified DO and temperature as the main physico-chemical parameters affecting distribution patterns and abundance of macroinvertebrate communities. The results provide information for the management and conservation of streams and rivers in Africa.