Physicochemical conditions prevailing at each station were also measured during each collection period. These parameters included water temperature, water width, dissolved oxygen concentration, biochemical oxygen demand (Winkler method) and pH (Aqua Merck. D6100, pH meter). Stream velocity was found using a Sensa Z300 OTT, and stream depth was recorded utilizing a search tube depth. Measures for nitrate and phosphate were determined for the water samples from each site, using the procedures by Greenberg et al. (1992) [24]. The other components such as riparian vegetation and pollution were also considered based on field observations. A Surber sampler (area= 30×30 cm2, mesh size = 250 μm) was used to collect 3 samples of macrobenthos at each sampling site monthly from February 2013 to January 2014. Three replicates were used up from different sub sites, two near the banks and one in the center to cover all different microhabitats (pools and riffles). Qualitative collections were as well created by examining rocks, wood dust, leaf detritus, and other microhabitats by hand at each sampling site. All invertebrate collections were preserved in 4% formaldehyde in the theater and then submitted to the lab for further screening, recognition, and enumeration then the beings were placed under a stereoscopic microscope.
Three metrics were utilized to show the diversity of the studied tax in each sample: Margalef’s richness, Shannon-Weaver's diversity index (Ĥ) and evenness index (E). Species richness in a habitat is the main parameter of taxonomic diversity and is handled as a surrogate for biodiversity [25]. Shannon-Weaver index is the most commonly used richness-based index of diversity, while evenness index is the cadence of accountability. These indices were computed by following methods: