Relevance: GS-3: Biodiversity, Environment, Security and Disaster Management

Key Phrases: coral bleaching, UNESCO , zooxanthellae, symbiotic relationship, El Niño, marine biodiversity, GCRMN, IPCC.

Why in News?

• The management authority of the world’s largest coral reef system, Australia’s Great Barrier Reef, confirmed on March 25 that the reef is experiencing a mass coral bleaching event.
• This is the sixth time that the coral reef system is being hit by a widespread and damaging bleaching event and the fourth time in six years that such an event has occurred.
• The bleaching event coincides with a 10-day UNESCO (United Nations Educational, Scientific and Cultural Organization) scientific mission currently underway in Australia.

What is Coral Bleaching?

• Bleaching happens when corals experience stress in their environment due to changes in temperature, pollution or high levels of ocean acidity.
• Under stressed conditions, the zooxanthellae or food-producing algae living inside coral polyps start producing reactive oxygen species, which are not beneficial to the corals.
• So, the corals expel the colour-giving zooxanthellae from their polyps, which exposes their pale white exoskeleton, giving the corals a bleached appearance. This also ends the symbiotic relationship that helps the corals to survive and grow.
• Bleached corals can survive depending on the levels of bleaching and the recovery of sea temperatures to normal levels.
• If heat-pollutions subside in time, over a few weeks, the zooxanthellae can come back to the corals and restart the partnership but severe bleaching and prolonged stress in the external environment can lead to coral death.

Why does it matter?

• Supports Marine Biodiversity
  • Coral reefs support over 25% of marine biodiversity, including fish, turtles and lobsters; even as they only take up 1% of the seafloor.
  • The marine life supported by reefs further fuels global fishing industries. Even giant clams and whales depend on the reefs to live.
• Economic significance
  • Besides, coral reef systems generate $2.7 trillion in annual economic value through goods and service trade and tourism.
  • In Australia, the Barrier Reef, in pre-COVID times, generated $4.6 billion annually through tourism and employed over 60,000 people including divers and guides.
  • Aside from adding economic value and being a support system for aquatic life, coral reefs also provide protection from storm waves.
• Dead reef revival requires more time
  • 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 the reef to start setting up again. The reefs which were severely damaged in 1998 did recover over time.
• Current condition of the Great Barrier Reef
  • The United Nations Intergovernmental Panel on Climate Change (IPCC) released its report this month, which warned that the life of the Great Barrier is in grave danger.
  • The report said that if temperatures continue to rise, bleaching events may occur more often and a large proportion of the remaining reef cover in Australia could be lost.

Steps to protect Coral Reefs

1. Recycle and Dispose of Trash Properly.
   • Marine debris can be harmful to coral reefs. Recycle your trash at home and on the go (especially plastic), and remember the three R’s (reduce, reuse, and recycle).
2. Minimize use of fertilizers.
   • The overuse of fertilizers harms water quality because nutrients (nitrogen and phosphorus) from the fertilizer are washed into waterways and eventually end up in oceans. These nutrients pollute the water and can harm coral reefs.
3. Practice general conservation.
   • Coral reefs are damaged when the general environment around them declines. So, we can help protect coral reefs simply by leading a more sustainable lifestyle.
4. Oppose global warming.
   • General worsening of the environment is an indirect way that people are causing harm to coral reefs. They are very sensitive to rising water temperatures, which cause them harm.
   • Reducing carbon footprint helps in stopping global warming and consequently protect coral reefs.
5. Spread the word
   • Many people touch or otherwise harm coral reefs without intending to do so. They may simply not understand that reefs are full of fragile living creatures and smallest contact can cause them harm.
   • Helping educate as many people as possible about coral reefs can make a difference.

Conclusion

• Coral reefs sit at the interface of two powerful societal trends. On the one hand, coral reef ecosystems provide vast resources to human communities, resources that are increasingly needed as the human population grows.
• On the other hand, coral reef ecosystems are existentially threatened by increased human-driven stresses, particularly the extensive coral mortality from severe bleaching events caused by warming seas on top of local stressors such as sedimentation, pollution, invasive species, and overfishing.
• Continuing disease threats and concerns about increasingly acidifying waters compound the risk posed to coral reefs.
• The increased reliance by humans on an ecosystem increasingly at risk of collapse has led to a widespread call for interventions that might preserve the services provided by coral reefs into the future.

Sources: The Hindu

Mains Questions

Q. How important are coral reefs to the marine ecosystem? Can this process be reversed and the reefs rejuvenated?(words 250).