About 97% of the world's water is salty and is found in our oceans and seas. But, as we can't drink seawater, how can it be important?
Every part of our seas and oceans contains an amazing number of animals and fish that live at different ocean depths. Most of the different species of animals and fish depend on simple plants for their food. These simple plants called algae (海藻) drift near the surface of the ocean and use sunlight to turn carbon dioxide and water into food and oxygen. In fact, algae produce over half of the oxygen people breathe. How important seawater is!
Each plant or animal in our seas and oceans is an important link in a food chain. The algae are eaten in large amounts by microscopic animals, which are in turn consumed by larger animals. These food chains are delicately balanced.
The bad news about the food chains in the oceans is that they are under threat because of man. People once thought that the oceans were so big that it didn't matter if we dumped rubbish into them or caught huge quantities of fish and whales for food. But we now know this is not true and fish stocks in the oceans have started to drop.
Thankfully, the world is taking steps to protect the future of our oceans by introducing international agreements to protect marine habitats. Most countries have introduced fishing restrictions to protect fish stocks in the oceans and new techniques are being pioneered to cope with pollution. Finally, the importance of protecting oceans is being made known to more people. This is just the beginning of a long process to protect the oceans for our future. We depend on the oceans for fish which are an important part of the human diet. How important seawater is!
【小题1】People used to think that the rubbish thrown into the sea ________.

Pierre is a 25-year-old penguin at the California Academy of Sciences. Due to his old age, he was going bald, which made him feel too cold to swim in the pool. Therefore, biologists at the academy had a wetsuit created for this penguin to help him get back in the swimming pool.
Unlike marine mammals, which have a layer of fat to keep them warm, penguins depend on their waterproof feathers. Without them, Pierre was unwilling to jump into the swimming pool and ended up trembling on the side of the pool while his 19 peers played in the water.
"He was cold; he would shake," said Pam Schaller, a senior biologist. Schaller first tried a heat lamp to keep Pierre warm. Then she got another idea: if wetsuits keep humans warm in the cold Pacific, why not make one for Pierre?
Schaller designed the suit, which covered Pierre’s body and had small openings for his flippers.
“I would walk behind him and look at where there were any gaps, and cut and refit and cut and refit until it looked like it was extremely suitable,” she said.
One concern was that the other penguins would reject Pierre in his new suit, but in fact, they accepted his new look. He swam freely and got along with others well, although he was the only penguin with a black stomach.
Schaller couldn’t say for sure whether the wetsuit allowed Pierre to recover his fine feathers, but “certainly we were able to keep him comfortable during a period of time that would have been very difficult for him to stay comfortable”.
Pierre will take off his suit after his new feathers grow back.
【小题1】Pierre felt too cold to swim in the pool because of _____.

Researchers in over 80 nations are taking part in a project to conduct a decade-long census(统计) of sea life. Scientists presented some of their findings at a recent conference as the project neared its completion.
In deep icy waters under Antarctica, scientists found bulbous tunicates, an underground animal, and many newly-discovered creatures believed to be related to starfish (海星) and other marine(海洋的）creatures.
Elsewhere in the world’s oceans, they have recently discovered many kinds of underwater life forms new to science. It is all part of a research effort called the Census of Marine Life.
“There are about 2,000 scientists worldwide involved,” said Bob Gagosian, President, CEO of the Consortium for Ocean Leadership. Gagosian helps manage the project. “Everywhere they’ve gone they’ve found new things,” he says. “The ocean basically is unexplored from the point of view of marine living things.”
Researchers have placed small markers on hundreds of fish and marine animals to track by satellite their migration(迁移）routes and to discover places where sea life gathers.
According to Ron O’Dor, a senior scientist with the Census of Marine Life, knowledge of life on the ocean floor is especially limited. “90% of all the information we have is from the top hundred meters of the ocean,” O’Dor states.
And he says the sea floor is, on average, at a depth of 4, 000 meters. And so, as some machines dive far below what people have previously seen, scientists are discovering new species of plants, animals and living things.
Since the census project began, more than 5,300 new marine animals have been found. Ocean researchers say they hope to catalogue 230,000 species during the census —which some say is only a small part of all the creatures living in the sea.
【小题1】Why do the researchers place small markers on many marine creatures?