The Coral Bleaching: Threat to marine ecosystem

Recently the Australia’s Great Barrier Reef system has confirmed that the reef is experiencing a mass coral bleaching event.

• It happened for the fourth time in six years now denoting frequent bleaching events causing threat to marine ecosystem.
  

• The first time coral bleaching event was caused in 1998. The EL NINO effect weather had caused the sea surface temperature to rise in the Pacific Ocean.
  • This event has caused 8%of the world’s corals to die.
  • Corals can survive bleaching effects but stressed to more temperature changes and can subject to mortality.
• Second time it took place in 2002.
  • Similarly in 2010, In Florida coral bleaching took place due to excessive cold water.
  • One of the major events took place between 2014 and 2017, which has affected 14% of the world’s corals.

Coral bleaching happens when corals experience stress in their environment due to changes in temperature, pollution or high levels of ocean acidity.

• Healthy corals- Coral and algae depend on each other to survive. Corals have a symbiotic relationship with microscopic algae called zooxanthellae that live in their tissues.
• These algae are the coral’s primary food source and give them their colour.
• Stressed Coral: if the corals are stressed then algae leaves the coral. When the symbiotic relationship becomes stressed due to increased ocean temperature or pollution, the algae leave the coral's tissue.
• Bleached coral: Coral is left bleached and vulnerable. Without the algae, the coral loses its major source of food, turns white or very pale, and is more susceptible to disease.
  

• Climate Change: The leading cause of coral bleaching is climate change.
• Increased temperature: Changes in ocean temperature or increased ocean temperature are the leading causes of coral bleaching.
• Pollution: Runoff and pollution Storm generated precipitation can rapidly dilute ocean water and runoff can carry pollutants — these can bleach near-shore corals.
• Overexposure: Overexposure to sunlight can make temperatures high and high solar irradiance contributes to bleaching in shallow-water corals.

• On Biodiversity- coral reefs support over 25% of the marine biodiversity, including fish, turtles and lobsters. They make up 1% of the sea floor.
  • The marine life supported by the reefs helps the fishing industry.
  • Even giant whales also depend on reefs to live.
• On Economy- corals reef system generates 7 trillion dollar in annual economic value through goods and services trade and tourism.
  • In Australia, coral reef system generates6 billion dollar worth trade annually.
  • It provides employment to 60000 people including divers and guides.
• On environment- it helps to maintain flora and fauna in marine ecosystem
  • It helps to prevent storm waves in oceans.

Present condition of the coral reef system

• According to the report of intergovernmental panel on climate change( IPCC)
• It has warned the life of Great Barrier Reef is in grave danger.
• Current bleaching effect has caused due to LA NINA effect.

• Coral reef mapping and reef health monitoring –
  • It is the initiative taken by India, where the coral reefs of Gulf of Kutchh, Gulf of Mannar, Andaman and Nicobar Islands, Lakshwadeep islands and Malvan are considered in Indian Ocean.
• Coral eco-morphological maps will be developed using satellite imageries in 1:25000 scales.
• This will indicate the health of corals and density etc.
• Global coral reef monitoring network-
• The first host institution for the new Implementation and Governance Plan is the Australian Institute of Marine Science, as part of Australia’s commitment to the ICRI Secretariat in 2019-2020 alongside co-chairs Monaco and Indonesia.
• The Global Coral Reef Monitoring Network (GCRMN) has been drawn up, utilising recommendations from a GCRMN meeting held in Townsville, Australia, on 23rd May 2017.
• Artificial coral formation-
• Materials used to construct artificial reefs have included rocks, cinder blocks, and even wood and old tires.
• Nowadays, several companies specialize in the design, manufacture, and deployment of long-lasting artificial reefs that are typically constructed of limestone, steel, and concrete.
• The first artificial coral reef has been commissioned in Kerela’s kovalam coast.
• It was 100m away from the coast and 30 m in breadth which was filled with sand to form’ soft reef ‘.
  
  

• Dead reefs can revive over time if there are enough fish species that can graze off the weeds that settle on dead corals, but it takes almost a decade for reefs to start setting up again.
• Artificial coral reefs are the future of the reef building in Indian Ocean to protect our marine ecosystem.
• Several governmental and intergovernmental Supports can bring a change in reducing the global Greenhouse gas emission and temperature to 5 degrees Celsius.
• Intergovernmental panel on climate change initiatives will make countries bound to scrutinize their coral reefs health.

Coral reefs are the largest living structure on earth has a great significance in marine ecosystem. There is an urgent need to reduce the carbon emissions and global temperature rises to make coral bleaching reduced.

India has a big role to play for its future commitments and targets to achieve to save environment and strategic Indian Ocean issues.