Warkineh, Bikila(PhD)Minas, Haileyesus2018-07-232023-11-092018-07-232023-11-092017-08http://etd.aau.edu.et/handle/123456789/9663Gulla River is one of the rivers impacted by anthropogenic activities. The most important factors affecting the river were land use modification, small scale irrigation system, town runoff, dumping of household wastes and organic debris. Data were gathered two times in December and May to observe the seasonal effects on macro invertebrates. Three sampling sites were selected to gather data through habitat, physicochemical and biological assessments. The habitat scores showed differences between the impacted and reference sites. The scores 52.92 and 51.25 put site-3 and site-2 into very poor category while the score 72.5 puts the reference site into good. There were significant differences (p<0.05) in most of the physicochemical parameters between stressed and reference sites. However, the value of EC, NO3 and DO were within the permissible limit set by WHO (1996) and Ethiopia EPA (2003). In this study the value of H-FBI also showed differences among the three sampling sites -Site-1(good), site-2(fair) and site-3(very poor) categories. A total of 297 macro invertebrates belonging to 25 families were collected and identified to compare the stressed sites to the reference site. The highest taxa were recorded in the reference (site-1) whereas the least was recorded in site-3.The BMI, percent EPT and percent Coleopterans tend to decrease as perturbation increased downstream in site-3 and site-2, but they increased in the reference site. On the other hand percent Chironomidae, Diptera, Oligochaeta, non-insect taxa, CLI and dominant taxa increased downstream as perturbation increased. Thus, macro invertebrates are good indicators of anthropogenic perturbation. Keywords: Macro invertebrates, Water pollution, physicochemical parameters, Aquatic ecosystem, anthropogenic activities.enMacro InvertebratesWater PollutionPhysicochemical ParametersAquatic EcosystemAnthropogenic ActivitiesThesis