Patterns of fish diversity, community structure and ecological integrity of River Yamuna, India

Abstract

The Yamuna River, one of the most important and sacred rivers of the northern plains of India, is highly polluted. The river originates at the Yamunotri glacier, traverses 120 km to emerge onto the Indo-Gangetic plains at Dakpathar in Uttarakhand, and finally joins the Ganges River at Allahabad after traversing 1376 km. During 2007–2010 this study assessed the fish diversity, community structure, and ecological status in a 1200 km stretch of the river from Dakpathar to Allahabad. The waters were alkaline (pH 7.6–8.0). Dissolved oxygen was high at most sites (7.3–9.8 mg l⁻¹), except at Wazirabad and Agra (3.4–3.7 mg l⁻¹). A total of 143 fish species were recorded in the river. Cyprinidae was the most abundant family followed by Schilbeidae, Bagridae, and Sisoridae, respectively. The abundance was dominated by 48 species with = > 250 individuals caught. The highest intersite species similarities were recorded between Yamunanagar and Panipat, followed by Wazirabad and Hamirpur, and Yamunanagar and Allahabad. The middle stretch of the river was dominated by small-bodied erytopic, indigenous, and exotic fish species with periodic and opportunistic life history strategies, and had reduced abundances of the large–bodied, prized Indian Major Carps. A trophic shift towards dominance of carnivore catfish species was evident. Multivariate analysis indicated 83.50% of the total variability in species composition in the river could be attributed to gradients of the environmental variables: dissolved oxygen, turbidity, conductivity, total dissolved solids, stream velocity, and water temperature.

Insufficient flows in the middle stretch of the river have altered fish habitat availability, resulting in changes in fish composition and assemblage patterns. The study will aid efforts to conserve the aquatic communities and their habitats in the river.