Amphibian and benthic macroinvertebrate response to physical and chemical properties of Themi River, Arusha, Tanzania

Abstract

I hypothesized that variation in physical and chemical properties and habitat destruction of the Themi River as a result of human activities would affect abundance and diversity of amphibian and benthic macroinvertebrates. Variation in habitat physical and chemical conditions, and amphibian and benthic macroinvertebrate diversity and abundance were assessed in the Themi River of Arusha municipality. These physical, chemical and biological conditions were assessed at forty sampling stations across four river sections (monitoring sites) that were located above and below municipal discharges. Water chemistry was evaluated by measuring the concentrations of SO4, Cu2+, Cl-, Cr6+, NO3-, PO43-, NH4+, turbidity, dissolved oxygen, water hardness (CaCO3) and pH. Water velocity, depth, width, temperature and damaged area were also measured. Shannon-wiener (H’) diversity, abundance and habitat destruction varied significantly among sampling stations. Diversity of amphibia and benthic macroinvertebrates decreased with increased habitat destruction, and changes in the chemical and physical properties of the river. These changes corresponded to changes in land use and discharges associated with human activities. Fresh water is crucial resource for humans and freshwater organisms in the Themi River. This study suggests that benthic macroinvertebrates and amphibians can be used to monitor human impacts on the Themi River and other rivers in Tanzania.