Before anyone can honestly care how important it is to protect marine habitats(生活环境), one needs to appreciate the vast quantities of marine life that exists in the ocean. It is hard for some people to relate to something they never see. However, it makes sense that the vast expanse of water and its inhabitants, covering 70% of the planet, affects us all.
Most marine animals are found near coral reefs. These colorful underwater forests naturally spring to mind with the mention of scuba(水中呼吸器)diving or underwater life. Coral reefs are constructed by living plants and animals, primarily corals that surround their small anemone (海葵)-like tentacles in a hard skeleton that forms much of the reef structure.
They generally occur in clear, tropical or semi-tropical seas to a depth of approximately 100 meters (328 feet). Coral reefs fringe approximately one sixth of the worlds coastlines and are the biologically richest of all shallow-water marine ecosystems. They support as many as 1 million species of animals and plants, but only a small fraction have been described. Among the best known groups are at least 5,000 species of fish, over 10,000 species of mollusk (软体动物) and more than 800 species of reef-building corals.
Corals are not only important to fish. Reefs are important to the human population for a wide variety or reasons: for one, they are a food source. A majority of people make their living fishing near coral reefs and an even larger part of population enjoys eating some of the catch. Unfortunately, if current trends of over-fishing continue, and we deplete fisheries as fast as we are, then this food source will eventually run out. Scientific evidence shows that 90% of top predators in the ocean are now extinct because of over-fishing-predatory fish include anything salmon sized and above all the way through sharks. On the other hand, killing off the grazing species of fish at reefs allows algae to build up, which in turn kills the coral. With 30% of oceanic fish making their home near coral reefs at one time or another, reefs are essential in maintaining a healthy fish population and many of the fish maintain the coral in return. Sustainable fishing is a must.
【英语六级(CET6)阅读理解模拟练习题及答案(8)】相关文章:
最新
2016-10-18
2016-10-11
2016-10-11
2016-10-08
2016-09-30
2016-09-30