River Dolphins go missing in Sunderbans as water salinity rises

Note4students

Mains Paper 3: Environment | Conservation, environmental pollution and degradation, environmental impact assessment

From UPSC perspective, the following things are important:

Prelims level: Gangetic Dolphin and its Habitat

Mains level: Conservation of the national aquatic animal


News

  • Rise in salinity in the water system that makes the Indian Sunderbans has resulted in the decrease of population of the Ganges River Dolphins (GRDs) in the region.

Findings of the study

  1. A recent study covering 100 km of rivers and channels around the Sunderbans have revealed that the national aquatic animal is no longer sighted in the central and eastern parts of the archipelago.
  2. Only in the western part of Sunderbans, where the salinity is lower, could researchers find some evidence of the species.
  3. The hyper-saline zone in the central part of the Sunderbans, which includes areas such as Raidighi and Patharpratima has lost connectivity with the upstream freshwater flow.
  4. Though there is some fresh water connectivity and flow in the eastern part, salinity levels were still high and thus there was no evidence of the GRDs.

Implications

  1. The study is indicative of how natural changes including the phenomenon of climate change and human interventions in the Indian Sunderbans are having an adverse impact on the habitat of the species.
  2. Because of its unique body shape, it becomes difficult for the dolphin to remain submerged in waters with high salinity.
  3. Hence freshwater flow to the Sunderbans is crucial for the subsistence of these species.

Impact of Sea-Level Rise

  1. The rise in sea level, triggered by climate change, is one of the reasons for the increase in salinity of waters of rivers and channels.
  2. Hydrological modifications like water diversion and commission of large barrages upstream have had a great impact on the salinity profile of the rivers downstream in the Sunderbans.

Back2Basics

Gangetic Dolphin

  1. Gangetic river dolphins fall under Schedule I of the Indian Wildlife (Protection) Act.
  2. It has been declared an ‘endangered’ species by the International Union for Conservation of Nature (IUCN).
  3. The Gangetic river species found in India, Bangladesh and Nepal is almost completely blind.
  4. It finds its way and prey using echoes with sound being everything for them to navigate, feed, escape danger, find mates, breed, nurse babies and play.
  5. The Gangetic river dolphin is one of the four freshwater dolphin species in the world.
  6. The other three are found in the Yangtze river, the Indus river in Pakistan and the Amazon river.
Wildlife Conservation Efforts
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