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thegurugyan_pib_environment_ecology_current_affairs

JUNE - 2020

Holocene extinction - The Sixth Mass Extinction

What is the Sixth Mass Extinction?

  • Mass extinction refers to a substantial increase in the degree of extinction or when the Earth loses more than three-quarters of its species in a geologically short period of time.
  • Researchers have described it as the “most serious environmental problem” since the loss of species will be irreversible.
  • Even though only an estimated 2% of all of the species that ever lived are alive today, the absolute number of species is greater now than ever before.
  • The research claims that this extinction is human-caused and is more immediate than climate destruction.
  • Significantly, the study calls for a complete ban on wildlife trade as many of the species currently endangered or on the brink of extinction are being decimated by legal and illegal wildlife trade.

 

Recent Research:

  • The ongoing sixth mass extinction may be one of the most serious environmental threats to the persistence of civilization, according to new research published in an American journal.
  • The study analysed 29,400 species of terrestrial vertebrates and determined which of these are on the brink of extinction because they have fewer than 1,000 individuals.
  • The disappearance of their component populations has been occurring since the 1800s.
  • Most of these 515 species are from South America (30 per cent), followed by Oceania (21 per cent), Asia (21 per cent) and Africa (16 per cent) among others.

 

What is Anthropocene/Holocene Extinction?

  • So far, during the entire history of the Earth, there have been five mass extinctions.
  • The sixth, which is ongoing, is referred to as the Anthropocene extinction or man-made extinction.
  • The five mass extinctions that took place in the last 450 million years have led to the destruction of 70-95 per cent of the species of plants, animals and microorganisms that existed earlier.
  • These five mass extinctions include the Ordovician Mass Extinction, Devonian Mass Extinction, Permian Mass Extinction, Triassic-Jurassic Mass Extinction, and Cretaceous-Tertiary (or the K-T) Mass Extinction.
  • These extinctions were caused by “catastrophic alterations” to the environment, such as massive volcanic eruptions, depletion of oceanic oxygen or collision with an asteroid.
  • After each of these extinctions, it took millions of years to regain species comparable to those that existed before the event.

 

What happens when species go extinct?

  • Fate of Environment is intertwined with every species, playing their exact role is important for survival of the surrounding.
  • When species go extinct, the impact can be tangible such as in the form of a loss in crop pollination and water purification.
  • Further, if a species has a specific function in an ecosystem, the loss can lead to consequences for other species by impacting the food chain.
  • The effects of extinction will worsen in the coming decades as the resulting genetic and cultural variability will change entire ecosystems.
  • If the number of individuals in a population or species drops, their contributions to ecosystem services become unimportant.

Dibru-Saikhowa National Park in Assam

Dibru-Saikhowa National Park:

  • The Oil India Ltd (OIL) leak in Assam has contaminated water bodies that flow into the Maguri Motapung Beel, a large wetland, and the Dibru-Saikhowa National Park (DSNP).
  • DSNP is a national park in Assam located in Dibrugarh and Tinsukia districts.
  • The park is bounded by the Brahmaputra and Lohit Rivers in the north and Dibru river in the south.
  • It mainly consists of moist mixed semi-evergreen forests, moist mixed deciduous forests, canebrakes and grasslands.
  • It is the largest Salix swamp forest in north-eastern India, with a tropical monsoon climate with a hot and wet summer and cool and usually dry winter.
  • It is known for Ferral horses, a total 36 species of mammals and above 400 species of birds have so far been recorded from the Dibru-Saikhowa National Park.
  • It is also identified as Important Bird Area (IBA) having more than 382 species of Birds, some of which are Greater Adjutant Stork, Lesser Adjutant Stork, Greater Crested Grebe.

Band-tail scorpionfish – A fish species found near Sethukarai coast in the Gulf of Mannar

Band-tail scorpionfish:

  • Researchers at the Central Marine Fisheries Research Institute (CMFRI) have found a rare fish from Sethukarai coast in the Gulf of Mannar.
  • The specimen has been deposited in the National Marine Biodiversity Museum of the CMFRI.
  • The band-tail scorpionfish (Scorpaenospsis neglecta) camouflages within the seagrass meadows.
  • The band-tail scorpionfish has spines which contain neurotoxic venom.
  • The fish get its name ‘scorpionfish’ because its spines contain neurotoxic venom.

MAY - 2020

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