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Coral reef with bright orange fish

Coral reefs

Coral reefs provide a home to about 25% of all marine species and are the most diverse of all the planet’s ecosystems, rivalling the diversity found in the Amazon rainforest. Estimates suggest that up to 2 million different types of animals thrive within or around coral reefs. That biodiversity represents livelihoods and food security for millions of people.

They are also one of the most sensitive ecosystems in the world, acting as a barometer for global warming. Just a small rise in the temperature of the oceans will cause coral reefs to bleach and potentially die, if the higher temperature is sustained. Additionally, increases in ocean acidification, which occurs as a result of the ocean absorbing more and more CO2, can affect some animals, such as corals, by reducing their ability to produce calcium carbonate to build skeletons or shells. This leaves them more vulnerable to damage and reduces their resilience.

Urgent action is needed to protect these vibrant underwater habitats from the effects of climate change, pollution, overfishing and other man-made factors - such as cyanide fishing, coral mining and poor tourism practices. More than half of the world’s reefs have already suffered irreversible damage.

Some 250 million people – many in small island states and developing countries - depend directly on coral reefs for food and income, making these populations particularly vulnerable to reef-loss. Coral reefs also provide vital protection to low-lying communities at risk from coastal flooding – in the 2004 tsunami, the reefs around the Maldives were credited with sparing the islands from the massive number of deaths experienced by other countries.

Experts say the decline of these precious underwater ecosystems can be prevented, and possibly regenerated, before it is too late - as long as the commitment to doing so starts now, to ensure they can be enjoyed by future generations.

Fast facts
  • A ‘coral’ is a community of individual ‘polyps’ which live communally in a colony.
  • A ‘reef’ is the result of many corals having grown on top of each other over 1,000’s of years.
  • A ‘barrier reef’ gets its name because it protects shallow waters from the open sea, ensuring the survival of many types of sea plant and life, as well as protecting the coastline.
  • Australia’s Great Barrier Reef, the largest in the world, covers 2600 miles and crosses over 500 islands.
  • It is estimated that at least half of the world’s coral reefs have died, or been seriously damaged, as a result of warmer waters in recent years.
  • Coral reefs can grow and be regenerated on artificial substrates, even on the hulls of sunken boats (though rusting hulks can also cause a biological chain reaction damaging to coral colonies).
  • A square kilometre of healthy, well managed coral reef can provide more than 15 tonnes of fish and other seafood each year.
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