Study on waterbird assemblages of the Middle Ganga river

Abstract

The Ganga River, one of Asia's most biodiverse riverine systems, exemplifies this ecological significance, hosting a rich assemblage of aquatic species, including over 150 waterbird species, and threatened taxa such as the Gangetic River dolphin, gharial, and Indian skimmer. However, these ecosystems face severe threats from climate change, habitat degradation because of anthropogenic activities, including unsustainable development, and pollution, leading to an estimated 10,000– 20,000 freshwater species being extinct or at risk of extinction globally. In India, the Ganga River is significantly impacted by the over-extraction of water from dams and barrages, industrial and sewage effluents, sand mining and riverbed agriculture, resulting in significant biodiversity loss. Waterbirds are key indicators that reflect the health of wetland and riverine ecosystems, owing to their sensitivity to environmental changes. Their roles as pollinators, seed dispersers, predators, and nutrient cyclers emphasise their ecological importance. In the Gangetic plains, waterbirds rely on the dynamic hydrological processes of rivers and associated wetlands for feeding, breeding, and roosting. Yet, these habitats are under immense pressure from urbanisation, agriculture, and pollution, with up to 40% of India's wetlands lost over the past 50 years. The middle stretch of the Ganga River, supporting rich diversity of waterbirds and other aquatic fauna, remains understudied, with limited comprehensive data on waterbird assemblages and their responses to a range of environmental and anthropogenic factors. This PhD thesis investigates the spatio-temporal patterns of waterbird assemblages along the middle stretch of the Ganga River, aiming to address critical knowledge gaps in their status, distribution, and ecological dependencies. The study pursues four key objectives: (1) to determine the status, distribution, and assemblage patterns of waterbirds; (2) to identify habitat features governing waterbird assemblages; (3) to assess the impacts of anthropogenic pressures; and (4) to prioritise areas for waterbird conservation. Through systematic surveys and ecological assessments, this research seeks to generate comprehensive data on waterbird diversity and evaluate the influence of habitat characteristics, such as channel depth and width, bank features, and water quality, alongside anthropogenic stressors like sand mining, solid waste dumps, pollution, and habitat fragmentation.