Published on: April 12, 2022



Yamada NEWS

Pollutants like microplastics may be causing growth defects in fish, including skeletal deformities, in the Cauvery river, a new study by IISC has revealed


  • Department of Molecular Reproduction, Development and Genetics conducted a comprehensive study of pollution at the KRS Dam and its potential effects on fish
  • Dissolved oxygen (DO) levels were much lower than they needed to be in samples collected from the slow-flowing and stagnant sites
  • Water from these sites also had microbes such as Cyclops, Daphnia, Spirogyra, Spirochaeta and E. coli, well-known bio-indicators of water contamination
  • Using a technique called Raman spectroscopy, the researchers detected microplastics – minute pieces of plastic often invisible to the naked eye – and toxic chemicals containing the cyclohexyl functional group (a functional group refers to atoms in a compound that determine its chemical properties).
  • Microplastics are found in several household and industrial products, and chemicals containing the cyclohexyl group, such as cyclohexyl isocyanate, are commonly used in agriculture and the pharmaceutical industry.
  • The team treated embryos of the well-known model organism, zebrafish, with water samples collected from the three sites, and found that those exposed to water from the slow-flowing and stagnant sites experienced skeletal deformities, DNA damage, early cell death, heart damage, and increased mortality
  • These defects were seen even after microbes were filtered out, suggesting that microplastics and the cyclohexyl functional groups are responsible for the ailments in the fish.
  • Unstable molecules called ROS (Reactive Oxygen Species) in the cells of the fish that developed abnormally was found. ROS build-up is known to damage DNA and affect animals