Fish Diversity and Water Quality in Different Zones of Upper River Indus Basin, Pakistan

Water quality assessment and freshwater fish diversity of cold-water Indus River, along a 400-kilometer stretch from Raikot (upstream) to Tarbela (downstream) was examined during 2019. The river channel was divided into five zones such as Raikot-Basha, Basha-Dasu, Dasu-Pattan, Pattan-Thakot and Thakot-Tarbela. The mean water quality of study site was as follows: pH 7.32, air temperature 21.15 degrees C, water temperature 15.9 degrees C, dissolved oxygen (DO) 6.41 mg/L, Total Dissolved Solids (TDS) 125.62 mg/L total hardness 77.50 mg/L, alkalinity 72.17 mg/L (as CaCO3) and conductivity 129.04 mu s/cm. Planktonic study revealed the presence of variety of phytoplankton (n=31) and zooplankton (n=3) species in study area. In total, 37 fish species were found in the study area, with species richness rising from zone one (n =10) to zone five (n =33). Altogether, the fish diversity represents 25 genera and 13 families. To analyze the data, principal component analysis (PCA) was done by using XLSTAT and excel 2019 to study the factors affecting the water quality. The eigenvalues obtained after PCA from zone 1 to zone 5 were 5.40, 2.40, 1.90, 0.28 and <0.28, respectively. The higher eigenvalue of zone 1 suggests large dispersion of data in this region. Furthermore, the findings in the study indicate that warm water, higher conductivity, DO, high nitrate concentration, and high salinity manifested to be the best habitat conditions downstream of Thakot area. To conserve the richness and integrity of fish communities, it is recommended that instream flow evaluations to include target species that occupy flow-sensitive habitat categories.