Guardians of the Ganges: Celebrating the Ganga River Dolphin on Ganga River Dolphin Day

Introduction:

Ganga River Dolphins, or "Susu", are a symbol of the Ganges riverine ecosystem, and stand as an epitome of India's rich biodiversity, embodying both cultural and ecological importance. Ganga River Dolphin Day celebrates this fascinating species, emphasizing the importance of conservation and research. This article unravels and explores the strides made in understanding their intelligence, behavior, and habitat through the lens of biology.

Biological Significance & Impact on Local Ecosystem:

Ganges River Dolphins, Platanista gangetica, serve as biological indicators of water quality and river health, as they are sensitive to water quality and habitat conditions. Their presence is an ecological barometer, reflecting the ecological integrity of the Ganges. As apex predators, they help regulate fish populations, contributing to the balance of the aquatic food web and promoting biodiversity. By rooting through riverbed sediments, they also stir up nutrients, benefiting aquatic plants and invertebrates. Their unique habitat requirements make them vital guardians of the river's biodiversity.

Survival and Endangerment:

Despite their importance, Ganga River Dolphins face numerous survival challenges, including habitat degradation, water pollution, accidental entanglement in fishing nets, and declining prey population. As a result, they are classified as Endangered on the IUCN Red List. Urgent Conservation efforts are crucial to prevent their extinction and preserve the Ganges riverine ecosystem.

Evolutionary and Genetic Lineage:

The Ganges River dolphin (Platanista gangetica) holds a unique evolutionary position among cetaceans. It is the last surviving species of the Platanistidae family, with a lineage dating back approximately 25 million years. Unlike its marine counterparts, this species has adapted to freshwater ecosystems over millions of years. Its striking features include a long, slender body, lack of a dorsal fin, and a flexible neck that facilitates navigating through the river's complex channels. Their eyes lack lenses, suggesting reliance on echolocation. This evolutionary distinctiveness highlights their importance in the aquatic ecosystems of the Ganges and Brahmaputra rivers (Braulik et al., 2018).

Genetically, Ganges River dolphins have shown distinct mitochondrial DNA variations, suggesting their separation from marine dolphin lineages millions of years ago. The Platanista gangetica represents an ancient lineage of toothed whales adapted to freshwater, with distinct morphological features for aquatic life. It's the only freshwater cetacean species found in the Ganges-Brahmaputra-Meghna River system.

Prominent Scientific Discoveries:

Studies by renowned biologist Dr. R.K. Sinha have significantly advanced our knowledge of Ganga River Dolphins. His research has shed light on their behavior, population dynamics, and conservation needs, guiding conservation efforts in India (Sinha et al., 2014). He conducted extensive field studies in the Vikramshila Gangetic Dolphin Sanctuary in Bihar, India. His work included observations on the social structure, feeding habits, and ecological significance of these dolphins. Sinha's research helped establish the importance of protecting the Vikramshila Sanctuary as a crucial habitat for the endangered Ganga River dolphins.

Scientific discoveries, like the analysis of Ganges River Dolphin vocalizations, have shed light on their communication methods. Their studies in the Chambal River revealed distinctive vocalizations, enhancing our understanding of dolphin behavior and social interactions (Sinha et al., 2014).

Indian scientists like Dr. A.K. Das's work on dolphin genetics has implications for conservation and understanding the species' evolutionary history (Das, A.K.). His work has focused on the biology and ecology of these dolphins, particularly in the Brahmaputra River of Assam, India. He has conducted research on the influence of environmental variables on the habitat and distribution of Ganga River dolphins in the Brahmaputra River. His studies have shed light on the specific environmental conditions that are critical for the survival of these dolphins, including water quality and habitat features. This research has highlighted the complex ecological relationships between the dolphins, their prey, and their habitat. Understanding these dynamics is crucial for devising effective conservation and management strategies.

Another scientist Dr. Sandeep Behera has been at the forefront of Ganga river dolphin research. He has conducted in-depth assessments of the habitat conditions, studying factors like water quality, flow patterns, and anthropogenic influences. Such studies provide vital inputs for habitat restoration initiatives. Dr. Behera's work includes collaborative efforts with communities living near riverine habitats to promote sustainable practices, reduce threats to the dolphins and emphasize the need for habitat conservation and sustainable fishing practices to protect these charismatic creatures (Behera et al., 2013).

Latest Advancements in Research:

State-of-the-art research employs non-invasive techniques such as underwater acoustics* to study Ganges River Dolphins. These advancements provide insights into their communication patterns and habitat preferences, aiding conservation strategies.

Modern research tools employ non-invasive techniques such as bioacoustics** and satellite tagging, that are revolutionizing Ganges River Dolphin research. These technologies provide real-time data on their behavior, communication patterns, movement patterns, and habitat preferences. Collaborative efforts are underway to utilize these advancements for effective conservation strategies.

Conclusion:

On Ganga River Dolphin Day, we celebrate these remarkable creatures, the biological sentinels of the Ganges. Their significance extends beyond biology, encompassing culture and conservation. By recognizing the pioneering work of Indian scientists and embracing the latest research advancements, we can ensure the survival and thriving of these invaluable river guardians and the rich biodiversity of the Ganges riverine ecosystem.

*Underwater acoustics (also known as hydro acoustics) is the study of the propagation of sound in water and the interaction of the mechanical waves that constitute sound with the water, its contents and its boundaries. In this case being used for mapping dolphin's migratory pattern and behaviour.

**The branch of acoustics concerned with sounds produced by or affecting living organisms, especially as relating to communication.

Written and researched by Harsiddhi A

References:

1. Braulik, Gill & Smith, Brian. (2018). Platanista gangetica, South Asian River Dolphin THE IUCN RED LIST OF THREATENED SPECIES?.

2. Sinha RK, Kannan K. Ganges River dolphin: an overview of biology, ecology, and conservation status in India. Ambio. 2014 Dec;43(8):1029-46. doi: 10.1007/s13280-014-0534-7. Epub 2014 Jun 13. PMID: 24924188; PMCID: PMC4235892.

3. Verma SK, Sinha RK, Singh L. Phylogenetic position of Platanista gangetica: insights from the mitochondrial cytochrome b and nuclear interphotoreceptor retinoid-binding protein gene sequences. Mol Phylogenet Evol. 2004 Nov;33(2):280-8. doi: 10.1016/j.ympev.2004.06.018. Erratum in: Mol Phylogenet Evol. 2005 Feb;34(2):456. PMID: 15336663.

4. Behera, Sandeep & Singh, Hari & Sagar, Viveksheel. (2013). Status of Ganges River Dolphin (Platanista gangetica gangetica) in the Ganga River Basin, India: A review. Aquatic Ecosystem Health & Management. 16. 10.1080/14634988.2013.845069.

5. Behera, Sandeep Kumar, Hari Singh, and Viveksheel Sagar. "Status of Ganges River dolphin (Platanista gangetica gangetica) in the Ganga River basin, India: A review." Aquatic ecosystem health & management 16.4 (2013): 425-432.

6. Tiwari, Nitish Kumar, Subhadeep Das Gupta, Himanshu Sekhar Swain, Dharm Nath Jha, Srikanta Samanta, Ranjan Kumar Manna, Archan Kanti Das, and Basanta Kumar Das. "Water quality assessment in the ecologically stressed lower and estuarine stretches of river Ganga using multivariate statistical tool." Environmental Monitoring and Assessment 194, no. 7 (2022): 469.