Coral Reefs: A Vital Marine Ecosystem 

• Coral reefs are hard skeletons left by marine polyps, forming reefs or atolls. 
• Made up of thousands of tiny invertebrates called polyps. 
• They are foundation species and dominant primary producers in marine ecosystems. 
• Coral reefs are biodiversity hotspots, supporting over 25% of marine life despite covering less than 1% of the ocean floor. 

Coral Reefs 

Formation of Coral Reefs 

• Coral larvae attach to sedimentary rocks or hard surfaces near coastlines. 
• Processes like sedimentation, compaction, cementation, and solidification aid reef formation. 

Types of Coral Reefs in India 

1. Fringing Reefs: Develop near coastlines, separated by shallow lagoons. 
2. Barrier Reefs: Located offshore, parallel to coastlines, with deep lagoons in between. 
3. Atolls: Circular reefs formed on mid-oceanic ridges, enclosing shallow lagoons. 

Conditions for Coral Reef Growth 

• Sunlight: Essential for zooxanthellae (algae) living inside corals, typically found in waters less than 50m deep. 
• Clear Water: Needed for sunlight penetration; sediment and plankton hinder growth. 
• Warm Water: Thrive in temperatures of 20–32°C. 
• Clean Water: Pollutants and sediments harm corals. 
• Saltwater: Cannot survive in freshwater regions like estuaries. 

Importance of Coral Reefs 

• Support the highest marine biodiversity per unit area. 
• Act as “medicine chests” with compounds used in medical treatments. 
• Sustain fisheries, tourism, and livelihoods. 
• Protect coastlines by buffering waves, storms, and floods. 
• Essential for island nations like the Maldives and Tuvalu. 

Coral Bleaching 

• Caused by rising ocean temperatures, leading corals to expel algae and turn white. 
• Bleaching weakens corals but does not necessarily kill them. 
• Cold stress can also lead to coral mortality. 

Mitigating Coral Bleaching 

• Reducing Greenhouse Gas Emissions: Limit global temperature rise to below 2°C. 
• Marine Conservation: Establish and manage protected marine areas. 
• Ecosystem Restoration: Use artificial structures and assisted breeding techniques. 
• Sustainable Fisheries Management: Enforce policies for controlled fishing. 
• Scientific Research: Invest in monitoring and studying ocean warming.