Brief Context
Context A study revealed that corals in the Lakshadweep archipelago have declined to half of what they were in 1998. What are Corals? Corals are invertebrates that belong to a large group of animals called Cnidaria.
Source Content
Syllabus: GS3/ Biodiversity and Conservation
Context
- A study revealed that corals in the Lakshadweep archipelago have declined to half of what they were in 1998.
- Over 24 years, coral cover declined from 37.24% to 19.6%, reflecting a roughly 50% reduction from the 1998 baseline.
What are Corals?
- Corals are invertebrates that belong to a large group of animals called Cnidaria.
- Corals are formed by multiple small, soft organisms known as polyps.
- They secrete a rocky chalk-like (calcium carbonate) exoskeleton around themselves for protection.
- Coral reefs are therefore created by millions of tiny polyps forming large carbonate structures.
- Appearance: Corals range in colour from red to purple and even blue, but are most commonly shades of brown and green.
- Coral are bright and colorful because of microscopic algae called zooxanthellae.
- There are three types of coral reefs – fringing reefs, barrier reefs and atolls.
- Fringing reefs form along shorelines, barrier reefs form in open water and atolls are circular reefs that have formed around sunken volcanoes.
- Coral reefs in India: Gulf of Kutch, Gulf of Mannar, Andaman & Nicobar, Lakshadweep Island and Malvan.
- Significance: They provide food, shelter, resting and breeding grounds to a quarter of all marine life, acting as nurseries and refuges to protect critical biodiversity.
- They also support more than 1 billion people living in coastal regions around the world by providing food, livelihoods and recreation.
Reasons for Coral Bleaching
- Marine Heatwaves & Climate Change: Rising sea surface temperatures disrupt the symbiotic relationship between corals and algae, causing mass bleaching and mortality.
- Ocean Acidification: Increased CO₂ dissolving into oceans reduces water pH, making it harder for corals to grow skeletons.
- Pollution: Runoff from land—containing fertilizers, pesticides, and heavy metals like lead—damages coral health and resilience.
- Physical Disturbance: Coastal development, unsustainable fishing, sedimentation, and coral mining physically damage or smother reefs.
- Overfishing: Reduces fish populations that control algae growth on reefs, further degrading coral environments.
Can corals recover from bleaching?
- Corals can recover from bleaching over time, but only if temperatures drop and conditions return to normal.
- When this happens, the algae returns and the corals gradually regain their health.
Source: TH