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Introduction:

Coral reefs are among the most biologically diverse marine ecosystems on Earth, having existed for around 200 million years.

They are essential to marine life, offering habitat for a wide variety of species, similar to tropical rainforests in terms of species richness and biological productivity.

Coral reefs support the formation of interconnected ecosystems, providing crucial habitats, fisheries, and livelihoods.

Body:

Coral Bleaching:

  • Occurs when water temperatures rise, causing corals to expel the symbiotic algae living in their tissues.
  • Without these algae, corals lose their color and turn white, a condition known as coral bleaching.
  • Although bleached corals are not dead, they become vulnerable to malnutrition and disease.
  • Corals can survive without algae for about two weeks, but prolonged stress can lead to mortality.

Thermal Stress:

  • Corals experience thermal stress when sea surface temperatures exceed 1°C above the average maximum temperature.
  • The Degree Heating Week (DHW) indicator measures accumulated heat stress over 12 weeks, tracking temperatures that exceed the bleaching threshold.

Marine Heatwaves:

  • The western Indian Ocean experienced the highest increase in marine heatwaves, approximately 1.5 events per decade.
  • The north Bay of Bengal followed with about 0.5 events per decade.
  • An underwater assessment in May 2020 showed that 85% of corals in the Gulf of Mannar, near the Tamil Nadu coast, bleached following a marine heatwave.

Conclusion:

Impact on Livelihoods and Ecosystems:

  • Heatwaves threaten the livelihoods of coastal communities, tourism, and the fisheries sector, and damage critical marine habitats like seagrass meadows.
  • Similar to corals, seagrass meadows and kelp forests face adverse effects such as impaired photosynthesis, reduced growth, and hindered reproduction due to heatwaves.

Indian Coral Reef Locations:

  • Coral reefs are found in the Gulf of Kutch, Gulf of Mannar, Andaman & Nicobar Islands, Lakshadweep Islands, and Malvan. These regions are vital for maintaining marine biodiversity and supporting local communities.
Legacy Editor Changed status to publish July 16, 2024