Comparison of macroinvertebrate assemblages and water quality between the channelized and unchannelized segment of Awetu stream, Jimma city, Southwestern Ethiopia

Abstract

Background: Freshwater ecosystems are increasingly modified worldwide by anthropogenic activities. Land cover change is one of the key factors responsible for stream ecosystem degradation. The most important impact on biodiversity and rivers around the world is the change in physical habitat due to channelization. Since 2020, Jimma city municipality is beautifying the city where one of the activities channelizing part of the Awetu stream crossing the city, where stream banks and riparian vegetation are being cleared. Therefore, the main aim of this study is to compare macroinvertebrate assemblages and water quality between the channelized and unchannelized segments of the Awetu stream . Methods: A cross-sectional study was employed from April 28 to May 02, 2022. Macroinvertebrates, water samples and habitat conditions were collected from 24 purposely selected sampling sites. Eleven of the sampling sites were located in the upstream unchannelized segment, eight sampling sites were from the channelized segment and five of the sampling sites were located in the downstream unchannelized segment of the Awetu stream . Samples were analyzed for different macroinvertebrate metrics and water quality parameters. Canonical Correspondence Analysis was used to examine the overall relationship between macroinvertebrate assemblages and water quality parameters. Result: Upstream site has better macroinvertebrate assemblages than channelized and downstream sites (p<0.05). The downstream site showed better assemblage though no significant variation was observed between the downstream and channelized site (p>0.05). Regarding water quality parameters (orthophosphate, total hardness, electrical conductivity, five-day biological oxygen demand, chloride and temperature) significant variation was observed between channelized and upstream sites (p<0.05). The habitat condition scores varied from 47 (poor) at channelization to 150 (suboptimal) at upstream. Conclusions: Upstream sites were found to have relatively high macroinvertebrate assemblages, better water quality and good habitat conditions. The downstream sites were lower macroinvertebrate assemblages, less habitat conditions, and poor water quality than upstream sites. The channelized sites were the poorest habitat condition, lower macroinvertebrate assemblages and poor water quality. Conservation of natural habitat conditions is a fundamental requirement for the species diversity and health of a strea