Assessment of the Water Quality of Chole River, Ethiopia using Benthic Macroinvertebrates and Selected Physicochemical Parameters

Abstract

The water quality of Chole River was assessed based oninsitu measurements and laboratory analyses of water and benthic macroinvertebrates samples collected for three rounds from January - April, 2017 once every two months from three sites coded S1, S2 and S3 using standard procedures. Laboratory analyses of benthic macroinvertebrates samples yielded5712 specimens belonging to 26 families and 9 Orders. Percentage of sensitive taxa (Ephemeroptera, Plecoptera and Trichoptera) (%EPT), Shannon diversity (H’), ETHbios score, Average Score Per Taxon and family richness decreased with increasing level of impacts from S1 through S3 to S2 in contrast to percentage of the tolerant Chironomidae (%Chiro.), percentage of dominant taxon (%DT) and Hilsonhoff’s Family Biotic Index (H-FBI).Mean %EPT was maximum at S1 (77.7%), followed by S3 (16.4%) and lowest at S2 (9.3%) whereas red Chironomidae dominated at S2 (84.6%) and S3 (91.8%). Family richness was maximum at S1 (25) and minimum at S2 (22). The lowest dissolved oxygen (4.29±1.85 mg/l) and maximum total phosphorus (6.09 ± 0.09) were determined at S2indicating organic and detergent pollutions, respectively. Electrical conductivity (609 ±169), Ammonium Nitrogen (0.091 ±0.067mg/l), Nitrate nitrogen (NO₃^-N) and (2.02 ± 0.141mg/l) picked at S3and remained relatively higher at S2.The heavy solid and liquid wastes loaded from Ambo University campus at S2 and common stressors at S3 including solid waste disposal, cattle watering, bathing, washing clothes and car washing might be responsible for the spatial variation in benthic macroinvertebrates indices/metrics and physicochemical parameterswhich indicateddeterioration in the water quality of Chole River at downstream sites.

Keywords: Biomonitoring, Ethiopia, macroinvertebrates, physicochemical parameters, Water Quality

DOI: 10.7176/JRDM/73-02

Publication date: February 28^th 2021