Gangetic dolphin

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  • 1.GANGETIC DOLPHIN (INDIAS NATIONAL AQUATIC ANIMAL) - BY SUDIP MITRA ( student of Msc. Environmental Science 4th sem. University of kalyani, department of environmental science). 1

2. Key Facts Common Name- Susu/ susuk. Scientific Name- Platanista gangetica. Geographic Habitat- Ganga, Brahamputra, Meghna river system of India, Bangladesh and Nepal, pakisthan. Length- 2.70 meter (Male), 2.12 meter (Female). Population- less than 2000 in India. Weight- 150-170 Kg. Status - endangered species. Distribution in india- it spread over seven state in india :- assam, u.p, m.p, rajasthan, bihar, jharkhand, west bengal. 2 3. CHARACTERISTICS OF GANGETIC DOLPHIN It is a blind species. It has low triangular dorsal fin. The claves are chocolate brown at birth and become greyish brown in adulthood with a smooth and hairless skin. Female attain sexual maturity at an 10-12 years, while males mature earlier( 6- 10 years.) Female are larger than male. They use ultrasonic sound for communication. In order to navigate the river and find food this dolphin uses echolocation which allows it to use echos to find objects in the environment and determine its size, distance, direction and density. The gestation period is 9-11 months and a female give birth to only one calf, once in 2-3 years. They have a long tapered body with a small fin located on the lower back and a long but narrow beak used for capturing food that may be hidden in narrow places or mud banks. 3 4. DIET The Ganges river dolphin can be found hunting a variety of freshwater fish and invertebrate such as catfish, clams and prawns. Some researchers believe that these dolphins may also consume birds, small turtles and small freshwater sharks. When it comes to hunting for food they generally hunt for prey living in shallow waters near the surface or in mud banks. Although they have a large beak used for finding hidden and burrowed prey they are unable to chew the food they capture and only use their beak to grab onto their prey swallowing their food whole. 4 5. Social Structure Due to their small population size the Ganges river dolphin can usually be found traveling alone or in small groups. In order to communicate with one another these dolphins use a series of clicks and whistles and each dolphin produces a unique frequency allowing one dolphin to determine who is speaking in the group. While not much is currently known about this species social structure in the past their species was much more abundant and affluent. Before the rivers become largely populated by humans these dolphins could be found swimming together in large schools or pods, which appears to indicate that social hierarchy and family may have played an important role in their survival and day-to-day living. 5 6. Platanista gangetica 6 7. GANGETIC DOLPHIN 7 8. Conservation status The Ganges River Dolphin is at the apex of the aquatic food chain and its presence in adequate numbers is an indication of great biodiversity in the river systems and helps keep a balanced ecosystem (Behera, 2007). It is categorized as endangered by IUCN, the World Conservation Union in the IUCN Red Data Book in 2002 (IUCN, 2004). The World Wildlife Fund-WWF recognizes this species as a flagship species for freshwater ecosystems. The Convention on International Trade in Endangered Species of Wild Flora and Fauna-CITES has listed this species as a species endangered by trade in Appendix I (CITES, 2005). The Ganges River Dolphin is legally protected throughout its range in South-East Asia. Government of india declared the animal as NATIONAL AQUATIC ANIMAL on 5th oct. 2009. 8 9. IMPORTANCE OF GANGA RIVER Flowing for 2,525 kilometres from the Himalayas to the Bay of Bengal, the Ganga is at the heart of the 800,000 square kilometre basin which supports around 300 million people in India, Nepal and Bangladesh. This cradle of the 5,000-year-old Indo-Gangetic civilisation is also Indias richest basin in terms of fish species a World Bank study published in 1996 had estimated around 350 species, while a 1991 study by P.K. Talwar of the Zoological Survey of India had reported 375. This diversity is at its richest at the myriad mouths of the Ganga, where it forms the worlds largest mangrove forest, the Sundarbans. Upstream, estimates of freshwater fish species vary between 104 and 161. The Ganga basin is the second richest in Asia in terms of biodiversity, following the Mekong. With a length 60% of that of the Mekong, it has 74 types (or genera) of fish, whereas the Mekong has 77. 9 10. SAND MINING:- sand mining increases turbidity and sedimentation , which reduce the suitability of the habitat for aquatic fauna and also dolphin. PESTICIDES USED IN AGRICULTURAL FIELD:- pesticides and fertilizer that used in agricultural field causes pollution. Untrated industrial waste. Sewage run-off into river and dam construction. There is high level of conflict between fisherman and river dolphin as they both concentrate in areas where most fish occur. OVERFISHING ACTIVITY AND BRICK KLIN. 10 11. Fishing activity in hooghly 11 12. THREATS 12 13. Dam construction and waste disposal 13 14. POACHING 14 15. KEY FACTS ABOUT POACHING River dolphins are poached for their oil and meat by some local communities. Dolphin oil is used either as a lure to catch catfishes or as a medicine for rheumatism. It is essential that the use of dolphin oil is banned. It is important that dolphin oil fishermen are given an alternative bait so that illegal poaching and trade does not continue. 15 16. SAND MINING 16 17. EFFECT OF SAND MINING Sand mining increase turbidity and sedimentation , which reduce the suitability of the habitat for aquatic fauna and also dolphin. 17 18. Sand mining in mangal dip(payradanga) 18 19. WHY RIVER DOLPHIN ARE POACHED? Dolphin oil is used either as a lure to catch catfish or as a medicine for rheumatism. River dolphin are poached for their oil and meat by some local community. 19 20. Brick manufactoring unit in around ganga river It causes huge air pollution( carbon mono- oxide, sox, Nox pollution). It causes arsenic pollution when they use underground water. The unhygenic living of brick klin worker causes negative impact on their lives and also pollute ganga river. It create child labour problem. 20 21. Picture of brick manufactoring unit in around payradanga- chakdaha 21 22. Picture of brick manufactoring unit in around payradanga- chakdaha 22 23. Ground water exploitation and AS pollution in surface water-body(Nadia) 23 24. Brick- klin in Nadia district 24 25. CREMATION SITE AROUND GANGA RIVER IT CAUSES WATER POLLUTION . IT HELP TO SPREAD DIESESES THROUGH DOG AND FOX. 25 26. CREMATION SITE PICTURE 26 27. GILL NET AND MOSQUITO NET GILL NET AND MOSQUITO NET KILLS DOLPHIN IN MONSOON AND PRE- MONSOON IN THEIR LOCALISE MIGRATION PERIOD. 27 28. MOSQUITO NET 28 29. GILL NET 29 30. What is overfishing? Overfishing is simply a situation where humans catch too much fish from the oceans (and also water bodies) in such massive quantities and fast pace than nature can naturally replenish. In other words, it is when we take out more fish than the fish can naturally replace. This leads to a degradation of our oceans, making it a non-sustainable use of the worlds river. 30 31. Other sources of pollution 31 32. Unknown fact about Ganga 1) Higher Dissolved Oxygen Content of Ganga: An Indian environmental engineer, D.S. Bhargava after three years of thorough study of Ganga concluded that Ganga is able to reduce its biochemical oxygen demand level much faster than other rivers. Bhargava says, organic materials usually exhaust a rivers available oxygen and starts putrefying. But in the Ganges, an unknown substance acts on organic materials and bacteria and kills them. He further adds Gangas self-purifying quality leads to oxygen levels 25 times higher than any other river in the world. 32 33. 2) Antibacterial Nature of Ganga Jal (Ganges Water):- Hindus have always believed Ganga Jal to be pure, pious and drinkable no matter what. Much reverence is given to Ganga water during Hindu rituals (from birth to death). But is there really any scientific validity to prove it? In 1896, Ernest Hanbury Hankin (a British bacteriologist) after testing the water from Ganga wrote a paper that was published in French Journal describing that the bacterium Vibrio Cholerae that causes the deadly cholera, when put into the waters of Ganga died within three hours. The same bacteria continued to thrive in distilled water even after 48 hours. He also suggested that the water of this river and its tributary Yamuna were responsible for containing the spread of deadly cholera in the region in those days. Similarly in 1927, Flix dHerelle (a French-Canadian microbiologist) was amazed to find no germs at all in water collected just few feet below the floating bodies of people who died of cholera and dysentery. The presence of bacteriophages (viruses that kill bacteria) in the water of Ganges is considered as the reason behind this quality and its purity. 33 34. 3) Antiputrefaction Properties of Ganga:- River waters usually tend to putrefy when the lack of oxygen promotes the growth of anaerobic bacteria that lends the water a distinct smell and stale taste. The water of Ganga though considered one of the dirtiest, does not tend to putrefy over longer periods of storage. In fact, British Physician, C.E. Nelson, observed that the Ganga water taken from Hooghly river (one of its dirtiest mouths) by returning ships to England remained fresh throughout the voyage. This was the reason East India Company ships only used water from Ganges for drinking purposes on their 3-month long voyage back to England because it stayed sweet and fresh. In a study conducted by Malaria Research Center in New Delhi it was observed that water from upper ambits of Ganga did not host mosquito breeding, and also pr