Analysis of spatial variation of physico-chemical parameters and macro invertebrate metrics in relation to Shonga river water quality status in Mizan-Aman Town, South west Ethiopia”

Abstract

Fresh water ecosystems are used to monitor and evaluate water quality and macro invertebrate as a key component. The Physico-chemical parameters and macro invertebrate fauna of Shonga River were studied from August 2016 to December 2016. Surface water and benthic macro invertebrate samples were collected from five sampling stations along the river. This covers the area lying between 1363 m.a.s.l at SR1 to 1326 m.a.s.l at SR5. The Shonga river crosses a wide area of farmlands and MTU, Mizan campus territory especially from SR2 to SR4 sampling sites and is mostly exposed to frequent runoff from Mizan to Aman highway and both the left and right side of MTU, point and non-point sources of waste to river. The samples were collected along the flow of the river from five sampling sites. SR1 sites were taken as the reference based on USEPA protocol. Benthic macro invertebrates were sampled from riffle or pool areas of the river and were identified to the family level following the standard methods in the laboratory. Physico-chemical parameters listed below were analyzed on site by employing were determined using in standard methods for examination of wastewater using multi parameters analyzer instrument. SPPSS version.16 and Excel software were employed for statistical analysis of samples. The range values of Surface water temperature was 19.32 to 22.12°C, Dissolved Oxygen 4.19 to 7.55mg/l, Biological Oxygen Demand 4.24 to 7.75mg/l, Electro Conductivity 55.07 to 71.44 us/cm and Alkalinity 32.32 to 35.60 mg/l. Generally of eight taxa comprising of 1063 individual species were recorded. The aquatic Diptera Chironomidae were the most abundant accounts 14 %, followed by Elmidae which accounted for 7.53% while Ephemerilidae was 7.15% of the percentage number. Finally, FBI value were classified water quality both of the upstream sites SR1 and downstream SR5 are Excellent and very good respectively, while it classified all the rest midstream sites were good to fair water quality.