Often called “rainforests of the sea,” coral reefs provide a home for 25% of all species in the ocean. They are stony structures full of dark hideaways where fish and sea animals can lay their eggs and 31 from predators. Without these underwater “apartment houses,” there would be fewer fish in the ocean. Some species might even become 32 or disappear completely.
There are thousands of reefs in the world; 33 , however, they are now in serious danger. More than one-third are in such bad shape that they could die within ten years. Many might not even 34 that long! Scientists are working hard to find out what leads to this destruction. There are still a lot of questions unanswered, but three main causes have been 35 .
The first cause is pollution on land. The pollutants run with rainwater into rivers and streams, which 36 the poisons into the ocean. Chemicals from the poisons kill reefs or make them weak, so they have less 37 to diseases.
Global warming is another reason. Higher ocean temperatures kill the important food source for the coral—the algae, the tiny greenish-gold water plants that live on coral. When the algae die, the coral loses its color and it also dies 38 . This process, known as “coral bleaching,” has happened more and more frequently in recent years.
The last factor contributing to the 39 of coral reefs is people. People sometimes crash into reefs with their boats or drop anchors on them, breaking off large chunks of coral. Divers who walk on reefs can also do serious damage. Moreover, some people even break coral off to collect for 40 since it is so colorful and pretty.
How can we help the reefs? We need to learn more about them and work together to stop the activities that may threaten their existence.
【題組】39. (A) eventually (B) disappearance (C) souvenirs (D) endangered (E) carry
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