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发表于 2014-7-8 18:14:54
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Part II: Speed
Rebounding whale populations are good for ocean ecosystems
BY Eli Kintisch | 3 July 2014
[Time 2]
Far from depleting the resources of ocean ecosystems, growing numbers of large whales may be critical to keeping these environments healthy. That’s the conclusion of a new study, which finds that rebounding populations of baleen and sperm whales may be boosting marine food webs around the world. The work is the latest volley in a long-running debate about the ecological role of whales and how their return to the oceans may affect global fisheries that face myriad threats.
Scientists have noted the gradual global recovery of various species of large whales. But many disagree about the impact this is having on ocean ecosystems. Some have cast whales as potential competitors to fishing fleets, because they vacuum up tons of invertebrates and small fish that might otherwise be available to commercially valuable species. Under that line of reasoning, some have argued in favor of the continuation of commercial whaling. In the 1970s and 1980s, for example, researchers argued that reducing certain whale populations would aid stocks of krill, a ubiquitous crustacean in the Southern Ocean that is a key food source for baleen whales and other marine species.
But the new study notes that krill populations remained constant or even declined after great whales experienced big declines. How so? The authors reason that the whales helped provide nutrients critical to krill and other species low on the food web. For instance, the mammals release massive "fecal plumes" and urine streams that fertilize surface waters with nitrogen and iron, the authors note, and help enhance productivity by mixing up the top layers of the ocean when diving.
Whales also move nutrients horizontally around the ocean. Humpback whales, for example, are a species of baleen whale known for grand migrations from the upper latitudes—like Pacific waters near Alaska—to the subtropics where nutrients are more scarce, near Hawaii and Mexico. Using historic and current population data, the study’s authors calculate that rebounded populations of whales could increase the productivity of phytoplankton in some subtropical waters by as much as 15% above the current level.
[342 words]
[Time 3]
Another underappreciated contribution to marine ecosystems, the authors report online today in Frontiers in Ecology and the Environment, is the bounty of organic material the animals provide to deep-sea ecosystems when they die. A so-called whale fall of a 40-ton gray whale provides a boost of carbon to the seafloor community equivalent to more than 2000 years of normal detritus and nutrient cycling.
“The reduction of whale carcasses during the age of commercial whaling may have caused some of the earliest human-caused extinctions in the ocean,” writes the study’s first author, conservation biologist Joe Roman of the University of Vermont in Burlington, in an e-mail. “More than 60 species have been discovered that are found only on whale falls in recent decades. By removing this habitat through hunting, we may well have lost many species before we even knew they existed.”
Such new understandings, Roman and his colleagues write, “warrants a shift in view from whales being positively valued as exploitable goods … to one that recognizes that these animals play key roles in healthy marine ecosystems.”
The new study is a useful addition to the debate on the role of whales in global ecosystems, writes marine ecologist Lisa Ballance of the National Oceanic and Atmospheric Administration in San Diego, California, in an e-mail. “As [whales] recover, we can indeed expect their influence on marine ecosystems to change the structure and function of those systems relative to the past 100 years.”
[242 words]
Source: new.science
http://news.sciencemag.org/environment/2014/07/rebounding-whale-populations-are-good-ocean-ecosystems
We dislike being alone with our thoughts
Many people would rather endure physical pain than suffer their own wandering cogitations.
BY Heidi Ledford | 3 July, 2014
[Time 4]
Which would you prefer: pain or boredom?
Given the choice, many people would rather give themselves mild electric shocks than sit idly in a room for 15 minutes, according to a study published today in Science.
The results are a testament to our discomfort with our own thoughts, say psychologists, and to the challenge we face when we try to rein them in.
“We lack a comfort in just being alone with our thoughts,” says Malia Mason, a psychologist at Columbia University in New York, who was not involved in the study. “We’re constantly looking to the external world for some sort of entertainment.”
In search of distraction
It was this observation that led social psychologist Timothy Wilson at the University of Virginia in Charlottesville and his team to embark on the study. Wilson and his colleagues began by asking undergraduate students to stash their mobile phones and other distractions, and to sit in a sparsely furnished room for up to 15 minutes. Afterwards, nearly half of the 409 participants said that they did not enjoy the experience.
The researchers were surprised. “We have this huge brain that’s full of pleasant memories and has the ability to tell stories and construct fantasies,” says Wilson, who says he often entertains himself as he falls asleep at night by imagining that he is a castaway on an unpopulated island. “It shouldn’t be that hard.”
Wilson’s team tried to make it easier. They decided that a more comfortable setting might make the experience more pleasant, so they repeated the experiment, this time allowing participants to perform the exercise at home. Nearly one-third of the study subjects later admitted to cheating.
Perhaps, the researchers reasoned, it was too difficult for participants to settle on a topic to think about. But advising participants to select a topic before the experiment also did not help.
[310 words]
[Time 5]
Shocking discomfort
Just how uncomfortable was the experience? In the next experiment, participants were given a small electric shock — akin to a jolt of static electricity — that was so unpleasant that three-quarters of them said they would be willing to pay not to experience the shock again. Yet when they were placed in the room to sit alone with their thoughts, 67% of male participants and 25% of female subjects were so eager to find something to do that they shocked themselves voluntarily.
Wilson thinks that the discomfort comes from a lack of mental control: that it is difficult to tell our minds to stay on one topic and keep it there for a long time. Subjects who reported a positive experience during the experiment tended to think about future events, often with loved ones. Those who did not enjoy the time for quiet reflection often thought about work.
That difficulty is not limited to college students: the results still held when researchers repeated the experiments with a broader age group sampled from a church and a farmer's market.
Mason says that the participants would have benefited from more guidance for their thinking — perhaps if they had been instructed not only to come up with a topic to ponder, but also to map out a more structured plan of where to take their thoughts from there. “It’s not enough to provide people with an entry point,” she says. “They need a direction to go in.”
Wilson intends to pursue ways to tame what he calls “the disengaged mind”. “There are lots of times in our daily lives, when we have a little bit of time out, or are stuck in traffic or trying to get to sleep,” says Wilson. “Having this as a tool in our mental toolbox as a way to retreat or reduce stress would be a useful thing to do.”
[313 words]
Source: nature
http://www.nature.com/news/we-dislike-being-alone-with-our-thoughts-1.15508
Exploding flower blasts birds with pollen
BY Xochitl Rojas-Rocha | 3 July, 2014
[Time 6]
Hidden high in the mountains of Ecuador and Costa Rica is an unusual genus of flowers called Axinaea. When researchers scaled up and down steep mountain slopes to install video cameras in the trees in which these flowers grow, they caught the plants offering a sugar-packed reward to visiting birds: the bellows organ, a bulbous, brightly colored appendage high in sugar and citric acid, which is attached to the plant’s male reproductive organ, or stamen. But as soon as the bird’s beak clamped down, the bellows organ forced air from its spongy tissues into a pollen chamber inside the stamen. The pollen exploded outwards, dusting the unwitting bird’s beak or forehead. When the bird flitted to another tree, it passed on the flower’s pollen to the receptive female organs of other flowers. This is the first case of a flowering plant offering up a food reward on a reproductive organ, the researchers report online today in Current Biology. They speculate that even before it evolved its bellows function, the bulbous organ’s resemblance to fruit seeds may have fooled birds into eating it.
[182 words]
Source: sciencenews
http://news.sciencemag.org/biology/2014/07/exploding-flower-blasts-birds-pollen
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