Coral reefs, found only in warm, shallow waters, are made up of groups of tiny animals called coral. When coral die, they leave behind hard skeletons(骨架) that build up and form reefs. As new coral grow on top, the reefs grow bigger. 【小题1】 Some look like boats, while others are shaped like horns. Some look almost like brains.

Coral reefs take centuries to grow. 【小题2】 Some threats are natural. Storms bring giant waves that can destroy coral to bits and pieces. When heavy rains wash soil off the land, the soil ends up in the water, and it blocks out the sunlight that coral need to grow.

Other threats, such as careless diving, come from humans. 【小题3】 Reef fish are highly sought by supermarkets and restaurants. To catch them alive so that they stay fresh longer some fishermen use a poison called cyanide. They spray the poison into the water, and it stuns(使……昏迷) the fish, but does not kill them. However, the poison can kill the coral and other reef inhabitants as well. Authorities are working hard to stop this kind of fishing. 【小题4】 “Fish need the reefs,” they explain. “If you kill the reefs, the fish will disappear. You are actually killing your own future.”

Another threat to reefs is harder to control. It is the rising water temperatures. Water that is too warm causes coral to get “bleached”or lose their color. Then they die. Some scientists think that global warming may be causing ocean waters to warm up quickly. 【小题5】

As warming continues, scientists warn the oxygen content of oceans across the planet could be more and more reduced, with serious consequences for the future of fish and other sea life.

【小题1】. One is the simple fact that as water gets warmer, it can hold less dissolved(溶解的)oxygen. The other reason is less obvious.【小题2】—either from the atmosphere, or from photosynthesizing algae floating at the top of the sea. The oxygen then spreads to the deep ocean as the surface water slowly sinks.

Global warming is expected to reduce the mixing of the ocean by making surface seawater lighter. That's because in a warmer world we can expect more rainfall and more melting of glaciers, icebergs, and ice sheets.【小题3】.The extra heat from the warming atmosphere will also make surface water expand and thus make it lighter still.【小题4】. Instead, more of the oxygen will remain near the surface, where it will be used up by oxygen-breathing organisms.

A low-oxygen ocean may become an inescapable feature of our planet. A team of Danish researchers wondered how long oxygen levels would drop if we could somehow reduce our carbon dioxide emissions to zero by 2100. They determined that over the next few thousand years oxygen levels would continue to fall, until they declined by 30 percent. The oxygen would slowly return to the oceans, but even 100,000 years from now they will not have fully recovered.【小题5】

In their spare time, most young people like to enjoy themselves and play on their smartphones. But Li Ruxue is different. He joined a sky-walker gibbon. (天行长臂猿) protection organization, where one of his major responsibilities was picking up gibbon feces (猿粪).

The skywalker gibbon is a top-level State protected animal whose population is smaller than that of wild giant pandas. Through analyzing their DNA from their feces, researchers can protect them better. So over the past four and a half years, Li has followed gibbons and collected their feces for researchers. Li said the job relies heavily on luck and willpower. “Our work and rest completely depend on gibbons. Though the lifestyle is a little bit tiring, it’s meaningful.” But he has never regretted his choice or felt alone, as he has found more young people engaged in nature conservation.

Like Li, Chu Wenwen, 27, has also worked to protect animals. Listed as a first-class State protected animal in China, the Mengxin beaver (蒙新河狸) is found only along the Ulungur River in Xinjiang’s Altay county. To protect them, Chu launched the “beaver canteen” program in 2018, in which a huge “canteen” of about 400,000 salix shrubs (灌木柳苗) was built with the snack money by mostly young internet users. “I am lucky to live in such a great era when young people can realize their dreams while the country strongly supports nature conservation,” said Chu.

According to Fan Pengfei, a professor at Sun Yat-sen University in Guangzhou, ecological protection as an industry can provide only a few jobs, most of which are in research institutes and nongovernmental organizations. But he has seen more and more young people take part time jobs as journalists, photographers and so on to raise awareness of wildlife protection. “Young people are the future of the world and the future of global biodiversity conservation,” noted Xinhua.