Fourth Mass Coral Bleaching

Context:

According to the U.S. NOAA, the world is on the verge of a fourth mass coral bleaching event which could see wide swathes of tropical reefs die, including parts of Australia’s Great Barrier Reef.

Relevance:

GS III: Environment and Ecology

Dimensions of the Article:

1. About Coral Reefs
2. Coral Bleaching and Its Implications
3. National Oceanic and Atmospheric Administration (NOAA) Findings

About Coral Reefs

• Indonesia has the largest coral reef area in the world and the Great Barrier Reef of the Queensland coast of Australia is the largest aggregation of coral reefs.
• India, Maldives, Sri Lanka and Chagos have the maximum coral reefs in South Asia.
• Coral Reefs protect humanity from natural calamities acting as a barrier, provide revenue and employment through tourism and recreation and also provide habitats for fishes, starfish and sea anemones.
• Coral blocks are used for buildings and road construction, the lime supplied by corals is used in cement industries and coral reefs may also be used in jewellery.
• India has four coral reef areas:
  • Gulf of Mannar,
  • Andaman and Nicobar Islands,
  • Lakshadweep islands
  • Gulf of Kutch.

Risks and threats to coral reefs

• Due to anthropogenic activities such as coastal development, destructive fishing methods and pollution from domestic and industrial sewage.
• Due to increased sedimentation, over-exploitation and recurring cyclones.
• Coral diseases such as black band and white band due to infectious microorganisms introduced by the human population that live on the coastal regions.

Coral Bleaching and Its Implications

Causes of Coral Bleaching:

• Exposure to stressful conditions, such as high temperatures, pollution, or changes in water chemistry, prompts corals to expel zooxanthellae.
• This expulsion leads to loss of color, resulting in the term “bleaching,” and, if prolonged, can be fatal for corals.

Concerns and Impact:

• Coral reefs, vital for marine ecosystems, provide habitats and sustenance for numerous fish species.
• They play a crucial role in coastline protection, storm prevention, and carbon dioxide absorption, contributing to climate regulation.
• The loss of coral reefs not only diminishes biodiversity and natural beauty but also impacts ecosystems and communities dependent on them.

National Oceanic and Atmospheric Administration (NOAA) Findings:

• The world is approaching a potential fourth mass coral bleaching event, following those in 1998, 2010, and 2014.
• Global significance requires widespread bleaching in the Atlantic, Pacific, and Indian Oceans.
• The last event (2014-2017) led to significant coral die-offs, with the Great Barrier Reef losing nearly a third of its corals.
• Preliminary data suggests that around 15% of the world’s reefs experienced substantial coral loss during that event.
• The current situation, exacerbated by climate change, is indicating a more severe scenario than the previous event.
• Factors include El Niño, leading to warmer ocean waters, and the Earth registering its first 12-month period with temperatures over 1.5 degrees Celsius above pre-industrial levels.
• Scientists believe a 1.5C rise is a critical threshold, estimating potential losses of 90% of the world’s coral reefs.

-Source: Down To Earth