The potential use of chironomids (Insecta: Diptera) as bioindicators in streams and rivers around Sebeta, Ethiopia

Abstract

The impact of human activities on streams and rivers of Ethiopia was assessed using the Dipteran family Chironomidae. Different stressors originating from industries and agricultural activities were assessed to see their effect on Chironomidae taxa. Chironomidae larvae were collected using a square frame handnet with frame dimensions of 25 × 25 cm and a mesh size of 500 μm. Six chironomid taxa were identified from nine sampling sites in four streams. Based on physico-chemical parameters, the sampling sites were clustered into four categories (minimally polluted, moderately polluted, highly polluted and extremely polluted). Chironomus alluaudi and Chironomus imicola were the dominant species in the highly polluted sites and were considered indicators of highly polluted streams and rivers. Abundances of Polypedilum wittei, Polypedilum bipustulatem and Dicrotendipus septemmaculatus, however, were relatively higher in moderately impacted sites and therefore described as indicators of moderately polluted sites. The genus Conchapelopia was mostly found in less impacted sampling sites and can be considered as an indicator of excellent water quality. Extremely polluted sites support low numbers of chironomid taxa in general and, as such, larval Chironomidae assemblages are important tools in assessing human impact on rivers when identified to genes/species level.