Water quality assessment using benthic macroinvertebrates as bioindicators in streams and rivers around Sebeta, Ethiopia

Abstract

The increasing impact of human activities on the freshwater-bodies of Ethiopia requires an efficient and cost-effective method for ecological health assessment. In the current study, benthic macroinvertebrates were used to assess the impact of different stressors originating from industries and agricultural activities on streams and rivers around Sebeta. A total of 20 benthic macroinvertebrate taxa were collected from nine sampling sites in four streams, representing the different levels of degradation. Human activities, such as laundry (GR1), livestock watering (MT1), and crop cultivation (KR2) minimally affect the receiving rivers and streams with a dissolved oxygen concentration of 5.01–7.86 mg l^-1, which helps to support 9–13 benthic macroinvertebrate taxa. Wastes and effluents from tannery (AB3), textile (GR2), brewery (MT2) and liquor (AB2) factories, however, greatly impact the receiving streams and rivers resulting in high loads of total phosphorus (up to 35.14 mg l⁻¹) and very low dissolved oxygen concentrations (up to 1.54 mg l⁻¹), which supports only 5 to 8 benthic macroinvertebrate taxa. Streams and rivers flowing through Sebeta town are highly degraded, because of industries established in the vicinity and research should focus primarily on waste minimisation and treatment technologies to maintain healthy river ecology.

Keywords: anthropogenic activities, aquatic ecosystems, ecological health assessment, stressors