25 August 2008

The Four Big Threats to Coral Reefs

1. Coral diseases
Scientists believe that runoff nutrients and sediment from the land, as well as high sea temperatures in summer, can cause coral diseases. There are about 30 known coral diseases, and the Great Barrier Reef has at least six of them. They include black-band disease, white syndrome, and coral tumours. Coral diseases are carried and spread by bacteria, fungi, algae, and worms.

2.Coral bleaching (as shown in the previous post)

3.Crown-of thorns starfish
Small numbers of this starfish on a reef are normal. They are simply part of the coral reef ecosystem. In large numbers, they eat corals faster than corals can grow and reproduce. A crown-of thorns starfish eats an area of coralthe same size as itself in a single day. In one year, one of these starfish can destroy 6 square yards of coral. If there are hundreds of them on a reef, it means destruction of the reef

People damage coral reefs in three main ways- through pollution, tourism, and fishing.
Not all coral reefs around the world are as healthy as the Great Barrier Reef. Since 2000, almost 30% of the world's reefs have been destroyed. It is estimated that 11% have been lost because of humans, through pollution, overfishing, dynamite fishing, minig of sand, or onshore building and development. Scientists think that two of every three reefs could disappear in the next 40 years! We need to protect and preserve these rain forests of the sea.

adapted from: On the job- Sea life scientist-Have you got what it takes to be a marine biologist? by Lisa Thompson

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