Spatial and temporal variation of zooplankton assemblage in the mining-impacted stretch of Ganga River, Uttarakhand, India

The spatial and temporal variation in the distribution, abundance and assemblage structure of zooplankton were examined in a mining-impacted stretch of river Ganga. The collection of samples has been done from three different sampling zones such as Z1 (Chandi Bridge Ghat) as reference zone, Z2 (Shyampur), and Z3 (Bisanpur) as mining-intruded area from May 2017 to April 2018. During the analysis, twenty-eight species of zooplankton kindred to four groups mainly Rotifera (ten species), Protozoa (five species), Cladocera (eight species), and Copepoda (five species) were identified. In the course of analysis, it was observed that Rotifera were dominant (43.49 %) followed by Cladocera (19.58 %), Protozoa (18.31 %), and Copepoda (18.62 %). The results showed that the distribution and abundance of zooplankton fluctuated more at Z1 (reference zone) as compared with Z2 and Z3 (mining-intruded zones). The diversity indices also indicated the higher richness, abundance, and evenness of zooplankton ranging from 3.145 to 3.180 at Z1, 3.081 to 3.129 at Z2, and 3.130 to 3.175 at Z3. The canonical correspondence analysis (CCA) showed positive and negative correlation between the zooplankton and water quality of the river Ganga. The present study shows that the anthropogenic activities such as river bed mining disturbed the water quality through enhancing the turbidity and nutrients load in the aquatic system. However, these changes in water quality significantly affected the distribution and abundance of zooplankton.