Coral Reefs

• Coral reefs are important ocean habitats and offer a compelling case of the risks of climate change.
• Reefs provide a large fraction of Earth’s biodiversity—they have been called “the rain forests of the seas.”
• Scientists estimate that 25 percent of all marine species live in and around coral reefs, making them one of the most diverse habitats in the world.
• Coral characteristics:
• Shallow water, reef-building corals have a symbiotic relationship with photosynthetic algae called zooxanthellae, which live in their tissues.
• Stable climatic conditions: Corals are highly susceptible to quick changes. They grow in regions where the climate is significantly stable for a long period of time.
• Perpetually warm waters: Corals thrive in tropical waters [30°N and 30°S latitudes, the temperature of water is around 20°C] where diurnal and annual temperature ranges are very narrow.
• Clear salt water: Clear salt water is suitable for coral growth, while both fresh water and highly saline water are harmful.
• Abundant Plankton: Adequate supply of oxygen and microscopic marine food called plankton [phytoplankton], is essential for growth. As the plankton is more abundant on the seaward side, corals grow rapidly on the seaward side.
• Little or no pollution: Corals are highly fragile and are vulnerable to climate change and pollution and even a minute increase in marine pollution can be catastrophic.

Source: NCERT