Abundance and diversity of benthic macroinvertebrates as bioindicators of water quality in Kuliya River at Areka Town Southern Ethiopia

Abstract In most aquatic environments, macroinvertebrates are used as biological tools to assess the impact of anthropogenic activities and pollutant levels. The present investigate was conductedon Kuliya River of Areka town in the southern Ethiopia between January to June 2023 to study thequality of water by using the distribution and abundance of benthic macroinvertebrates along with their physico chemical parameters.Three sampling sites were selected across the river, each differ from the other at least by 5 km apart based on their anthropogenic activities. Water samples were collected for both benthic macroinvertebratesby using kick and multi-habitat sampling methodswhereasselected physicochemical parameters including DO, temperature, pH, TDS, phosphates, nitrates, nitrites BOD, COD were measured according to protocols. Most of the selected physicochemical parameters except ammonia and ammonium showed a significant difference.A total of 1082 macroinvertebrate individuals, belonging to 18 families, 7 orders, and 1 class were identified. The 533 families from the pollution-tolerant order Diptera were found at site 3 indicating they were highly abundant there. In contrast, 244 families from the EPT (Ephemeroptera, Plecoptera, and Trichoptera) order were found at site 1, suggesting they were more abundant at site 1 than at site 3. This indicates that site 3 was highly impacted by anthropogenic activities. The Hilsenhoff Family biotic index values were 3.80, 7.04, and 8.18 at sites 1, 2, and 3, respectively, indicating possible slight organic pollution, significant organic pollution, and highly significant organic pollution. The distribution of macroinvertebrates had showed a significant difference. Similarly, the Shannon-Wiener diversity index values were 2.35, 1.72, and 0.99 at Sites 1, 2, and 3.The association between macroinvertebrates and physicochemical parameters was demonstrated by canonical correspondence analysis showing a negative correlation with most-pollution sensitive macroinvertebrates. This indicated that the Kuliya River is under anthropogenic stress for whichproper water quality management and continuous monitoring is to be made.