• ICAR-Central Marine Fisheries Research Institute (CMFRI) has found that Lakshadweep has been affected by MHWs since October 2023, resulting in coral bleaching. 
  • Primary causes of these MHWs are changes in ocean currents and excessive heat transfer into atmosphere, which results in abnormally high water temperatures.
  • Coral bleaching happens when corals lose their vibrant colors and turn white. It is mainly caused due to changes in temperature, light, or nutrients. 

About MHWs

• It is defined when seawater temperatures exceed a seasonally-varying threshold (usually the 90th percentile) for at least 5 consecutive days.

• MHWs can last for weeks, months or even years.

Impacts of MHWs

• MHWs can cause extreme weather events such as tropical storms and hurricanes.
• Reduction in monsoon rainfall over Central India.
• Native species are forced to migrate to cooler waters, and invasive species such as sea urchins, jellyfish etc. thrive.
• Higher temperatures, combined with water de-oxygenation, can lead to toxic algal bloom.
• Livelihood loss due to increased mortality of economically important species.
• Biodiversity and Habitat loss due to food web disruption.