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天鹅个体大、寿命长、存活率高，适应于稳定的栖息环境，不具有较大的迁徙范围，但具有较强的竞争能力，种群密度较稳定。( )
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Fishermen on the high seas have plenty of worries, not the least of which are boat-tossing storms, territorial squabbles and even pirates. Now Boris Worm, a marine biologist at Dalhousie University in Halifax, Canada, has added another. After studying, among other things, global catch data over more than 50 years, he and a team of 13 researchers in four countries have come to a stunning conclusion. By the middle of this century, fishermen will have almost nothing left to catch. "None of us regular working folk are going to be able to afford seafood," says Stephen Palumbi, a Stanford University marine biologist and co-author of the study published in Science. "It’s going to be too rare and too expensive." Don’t tell that to your local sushi chef. Over the past three decades, the fish export trade has grown fourfold, to 30 million tons, and its value has increased ninefold, to $71 billion. The dietary attractiveness of seafood has stoked demand. About 90% of the ocean’s big predators—like cod and tuna—have been fished out of existence. Increasingly, fish and shrimp farms are filling the shortfall. Though touted as a solution to overfishing, many of them have—along with rampant coastal development, climate change and pollution—devastated the reefs, mangroves and seagrass beds where many commercially valuable fish hatch. Steven Murawski, chief scientist at the U. S. National Marine Fisheries Service, finds Worm’s headlining prediction far too pessimistic. Industry experts arc even more skeptical. "There’s now a global effort to reduce or eliminate fishing practices that aren’t sustainable," says industry analyst Howard Johnson. "With that increased awareness, these projections just aren’t realistic." Perhaps. Still, the destructive fishing practices that have decimated tuna and cod have not declined worldwide, as Johnson suggests. Up to half the marine life caught by fishers is discarded, often dead, as bycatch, and vibrant coral forests are still being stripped bare by dragnets. Worm argues that fisheries based on ecosystems stripped of their biological diversity are especially prone to collapse. At least 29% of fished species have already collapsed, according to the study, and the trend is accelerating. So what’s a fish eater to do "Vote with your wallet," says Michael Sutton, who runs the Monterey Bay Aquarium’s Seafood Watch program in California. Since 1999, the aquarium has handed out pocket guides listing sustainably harvested seafood. The Marine Stewardship Council has partnered with corporations to similarly certify wild and farm-raised seafood. Some 370 products in more than two dozen countries bear the British group’s "Fish Forever" label of approval. Wal-Mart and Red Lobster, among others, have made commitments to sell sustainably harvested seafood. But that’s just a spit in the ocean unless consumers in Japan, India, China and Europe join the chorus for change. "If everyone in the U. S. started eating sustainable seafood," says Worldwatch Institute senior researcher Brian Halweil, "it would be wonderful, but it wouldn’t address the global issues. We’re at the very beginning of this.\ According to the passage, one solution to the extinction of many fish species is that
In this section you will hear everything ONCE ONLY. Listen carefully and then answer the questions that follow. Mark the correct answer to each question on your answer sheet. Question 6 is based on the following news. At the end of the news item, you will be given 10 seconds to answer the question. Now listen to the news.
In this section you will hear everything ONCE ONLY. Listen carefully and then answer the questions that follow. Mark the correct answer to each question on your answer sheet. Questions 1 to 5 are based on an interview. At the end of the interview you will be given 10 seconds to answer each of the following five questions. Now listen to the interview. According to the interview, which of the following statements is TRUE about Sam
Long-married couples often schedule a weekly "date night"—a regular evening out with friends or at a favorite restaurant to strengthen their marital bond. But brain and behavior researchers say many couples are going about date night all wrong. Simply spending quality time together is probably not enough to prevent a relationship from getting stale. Using laboratory studies, real-world experiments and even brain-scan data, scientists can now offer long-married couples a simple prescription for rekindling the romantic love that brought them together in the first place. The solution Reinventing date night. Rather than visiting the same familiar haunts and dining with the same old friends, couples need to tailor their date nights around new and different activities that they both enjoy, says Arthur Aron, a professor of social psychology at the State University of New York at Stony Brook. The goal is to find ways to keep injecting novelty into the relationship. The activity can be as simple as trying a new restaurant or something a little more unusual or thrilling—like taking an art class or going to an amusement park. The theory is based on brain science. New experiences activate the brain’s reward system, flooding it with dopamine and norepinephrine. These are the same brain circuits that are ignited in early romantic love, a time of exhilaration and obsessive thoughts about a new partner. (They are also the brain chemicals involved in drug addiction and obsessive-compulsive disorder.) Most studies of love and marriage show that the decline of romantic love over time is inevitable. The butterflies of early romance quickly flutter away and are replaced by familiar, predictable feelings of long-term attachment. But several experiments show that novelty—simply doing new things together as a couple—may help bring the butterflies back, recreating the chemical surges of early courtship. Over the past several years, Dr. Aron and his colleagues have tested the novelty theory in a series of experiments with long-married couples. In one of the earliest studies, the researchers recruited 53 middle-aged couples. Using standard questionnaires, the researchers measured the couples’ relationship quality and then randomly assigned them to one of three groups. One group was instructed to spend 90 minutes a week doing pleasant and familiar activities, like dining out or going to a movie. Couples in another group were instructed to spend 90 minutes a week on "exciting" activities that appealed to both husband and wife. Those couples did things they didn’t typically do—attending concerts or plays, skiing, hiking and dancing. The third group was not assigned any particular activity. After 10 weeks, the couples again took tests to gauge the quality of their relationships. Those who had undertaken the "exciting" date nights showed a significantly greater increase in marital satisfaction than the "pleasant" date night group. While the results were compelling, they weren’t conclusive. The experiment didn’t occur in a controlled setting, and numerous variables could have affected the final results. More recently, Dr. Aron and colleagues have created laboratory experiments to test the effects of novelty on marriage. In one set of experiments, some couples are assigned a mundane task that involves simply walking back and forth across a room. Other couples, however, take part in a more challenging exercise—their wrists and ankles are bound together as they crawl back and forth pushing a ball. Before and after the exercise, the couples were asked things like, "How bored are you with your current relationship" The couples who took part in the more challenging and novel activity showed bigger increases in love and satisfaction scores, while couples performing the mundane task showed no meaningful changes. Dr. Aron cautions that novelty alone is probably not enough to save a marriage in crisis. But for couples who have a reasonably good but slightly dull relationship, novelty may help reignite old sparks. And recent brain-scan studies show that romantic love really can last years into a marriage. Last week, at the Society for Personality and Social Psychology conference in Albuquerque, researchers presented brain-scan data on several men and women who had been married for 10 or more years. Interviews and questionnaires suggested they were still intensely in love with their partners. Brain scans confirmed it, showing increased brain activity associated with romantic love when the subjects saw pictures of their spouses. It’s not clear why some couples are able to maintain romantic intensity even after years together. But the scientists believe regular injections of novelty and excitement most likely play a role. The application of the novelty theory is NOT affected by
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