Time is Up!
Reading Test 51
El Nino and Seabirds
A.
Rhythm of the seasons cannot always be relied upon. At times the tropical Pacific Ocean and large expanses of the global atmosphere seem to be marching to the beat of a different drummer, disrupting the normal patterns of countless species of plants and animals along with hundreds of millions of human beings. So they want anticipate these occasional lapses in the march of the seasons and help societies plan accordingly, scientists are seeking to understand these competing rhythms: the strongest of which is the alternation between the “normal climate” and a different but still recurrent set of climatic conditions in the Pacific region called El Nino.
B.
Seabirds are prominent and highly visible components of marine ecosystems that will be affected by global climate change. The Bering Sea region is particularly important to seabirds; populations there are larger and more diverse than in any similar region in North America—over 90% of seabirds breeding in the continental United States are found in this region. Seabirds, so named because they spend at least 80% of their lives at sea, are dependent upon marine resources for food. As prey availability changes in response to climatically driven factors such as surface sea temperature and extent of sea ice, so will populations of seabirds be affected.
C.
Seabirds are valued as indicators of healthy marine ecosystems and provide a “vicarious use value” or existence value—people appreciate and value seabirds simply because they are there and enjoy them through venues such as pictures, nature programs, and written accounts without ever directly observing seabirds in their native environment. A direct measure of this value is demonstrated by Federal legislation that established specific national wildlife refuges to protect seabirds and international treaty obligations that provide additional protection for seabirds. Seabirds are also an important subsistence resource for many who live within the Bering Sea Region. Furthermore, the rich knowledge base about seabirds makes them a valuable resource as indicator species for measurement of change in the marine environment.
D.
The most abundant breeding species in Alaska are northern fulmars, storm-petrels, kittiwakes, murres, auklets and puffins. These species also form the largest colonies. Fulmars, storm-petrels and kittiwakes are surface feeders, picking their prey from the surface or just below the surface; murres, auklets, and puffins dive for their food. Fulmars nest primarily on island groups in and around the Bering Sea. They take a wide variety of prey (e.g., fish, squid, zooplankton, jellyfish) from the surface or just below the surface. Storm-petrels are strictly nocturnal and nest below ground in either burrows or crevices between rocks. They forage on zooplankton and squid; in some areas they are dependent upon small fish such as capelin and sand lance caught at the surface. Black-legged kittiwakes are widespread throughout Alaska, Canada and Eurasia while red-legged kittiwakes are found only in the Bering Sea region. Both are surface feeders although black-legged kittiwakes feed primarily on small fish and forage over the continental shelf and shelf break; red-legged kittiwakes feed primarily on myctophids and will forage beyond the shelf break.
E.
Marine mammals have exhibited similar signs of food stress in recent years. Harbor seals at Tugidak Island in the Gulf of Alaska declined by about 85% between 1976 and 1988. Steller sea lion populations declined by 36% in the Gulf of Alaska between 1977 and 1985, and by another 59% between 1985 and Northern fur seals declined about 35% by 1986 from their average numbers in the 1970s, although numbers had rebounded somewhat (20%) by 1990. Associated with the declines in Steller sea lions are declines in birth rate, fewer breeding females, fewer pups, decreased adult body condition, decreased juvenile survival, and a change in population age structure.
F.
Walker noticed that monsoon seasons with low-index conditions are often marked by drought in Australia, Indonesia, India, and parts of Africa. He also claimed that low-index winters tend to be unusually mild in western Canada. One of his British colleagues chided him in print for suggesting that climatic conditions over such widely separated regions of the globe could be linked. In his reply Walker predicted, correctly, that an explanation would be forthcoming, but that it would require a knowledge of wind patterns above ground level, which were not routinely being observed at that time.
G.
The need for long-term time series It seems obvious that without good baseline data ornithologists are doomed to be surprised by the arrival of El Nino every few years. Even when ornithologists and ecologists are at hand to take advantage of an incoming El Nino, lack of preexisting data, and of monitoring afterwards, makes it difficult 134 FM. Jaksic & J.M. Farina to understand responses of birds to the successive El Nino, La Nina, and “normal” years. Indeed, according to Jaksic, during the last century there were 12 El Nino years and 12 La Nina years, thus leaving about 76 ‘normal’ years in between. Thus, by heavily concentrating attention on only 12% of the time span El Nino, and of neglecting possibly another 12%, ornithologists are essentially ignoring what happens during 76% of the time. This situation may be remedied only as long as data are logged on a regular or continuous basis, that is, as long-term time series. “The precise prescribed by Schreiber & Schreiber to understand El Nino, effects on birds still stands: ‘…carry out long-term studies that will shed further light on the interactions between global atmospheric cycles, oceanographic phenomena, and avian populations.’”
H.
Populations of seabirds in Alaska are larger and more diverse than any similar region in the Northern Hemisphere. The extensive coastal estuaries and offshore waters of Alaska provide breeding, feeding and migrating habitats for 66 species of seabirds. At least 38 species of seabirds, over 50 million individuals, breed in Alaska. Eight Alaskan species breed only here and in adjacent Siberia. Five additional species range through the North Pacific, but their populations are concentrated in Alaska. In addition to breeding grounds, Alaskan waters also provide important wintering habitat for birds that breed in Canada and Eurasia. Shearwaters, which breed in the southern hemisphere, are the most numerous species in Alaskan waters during the summer.
I.
As another indication that food has been limiting in recent years, several large scale die-offs of seabirds, mostly surface-feeding species, have been observed in the Gulf of Alaska during the last decade, most notably in 1983, 1989, and 1993. But Hatch thinks that it is too early to decide if these die-offs reports are somehow connected with effect of El nino. Byrd and Tobish believe that high rainfall can affect survival of chicks in earthen burrows, and incidence of big storms with high winds during the chick-rearing period can cause mortality for chicks of species nesting on cliff-ledges, but this view has not been considered as convincing evidence.
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Conquering Earth’s Space Junk Problem
Last year, commercial companies, military and civil departments, and amateurs sent more than 400 satellites into orbit, over four times the yearly average in the previous decade. Numbers could rise even more sharply if leading space companies follow through on plans to deploy hundreds to thousands of large constellations of satellites to space in the next few years.
All that traffic can lead to disaster. Ten years ago, a US commercial Iridium satellite smashed into an inactive Russian communications satellite called Cosmos-2251, creating thousands of new pieces of space shrapnel that now threaten other satellites in low Earth orbit – the zone stretching up to 2,000 kilometres in altitude. Altogether, there are roughly 20,000 human-made objects in orbit, from working satellites to small rocket pieces. And satellite operators can’t steer away from every potential crash, because each move consumes fuel and the fuel that could otherwise be used for the spacecraft’s main job.
Concern about space junk goes back to the beginning of the satellite era, but the number of objects in orbit is rising so rapidly that researchers are investigating new ways of attacking the problem. Several teams are trying to improve methods for assessing what is in orbit so that satellite operators can work more efficiently in ever-more crowded space. Some researchers are now starting to compile a massive data set that includes the best possible information on where everything is in orbit. Others are developing taxonomies of space – working on measuring properties such as the shape and size of an object so that satellite operators know how to worry about what’s coming their way.
The alternative, many say, is unthinkable. Just a few uncontrolled space crashes could generate enough debris to set off a runaway cascade of fragments, rendering near-Earth space unusable. “If we go on like this, we will reach a point of no return,” says Carolin Frueh, an astrodynamical researcher at Purdue University in West Lafayette, Indiana.
Even as our ability to monitor space objects increases, so too does the total number of items in orbit. That means companies, governments, and other players in space are collaborating in new ways to avoid a shared threat. International groups such as the Inter-Agency Space Debris Coordination Committee have developed guidelines on space sustainability. Those include inactivating satellites at the end of their useful life by venting pressurized materials or leftover fuel that might lead to explosions. The intergovernmental groups also advise lowering satellites deep enough into the atmosphere that they will burn up or disintegrate within 25 years. But so far, only about half of all missions have abided by this 25-year goal, says Holger Krag, head of the European Space Agency’s space debris office in Darmstadt, Germany. Operators of the planned large constellations of satellites say they will be responsible stewards in their enterprises in space, but Krag worries that problems could increase, despite their best intentions. “What happens to those that fail or go bankrupt?” he asks. They are probably not going to spend money to steer their satellites from space.”
In theory, given the vastness of space, satellite operators should have plenty of room for all the missions to fly safely without ever nearing another object. So some scientists are tackling the problem of space junk by trying to find out where all the debris is so a high degree of precision. That would alleviate the need for many of the unnecessary maneuvers that are carried out to avoid potential collisions. “If you knew precisely where everything was, you would almost never have a problem,” says Marlon Sorge, a space-debris specialist at the Aerospace Corporation in El Segundo, California.
The field is called space traffic management because it’s similar to managing traffic on the roads or in the air. Think about a busy day at an airport, says Moriba Jah, an astrodynamicist at the University of Texas at Austin: planes line up in the sky, landing and taking off close to one another in a carefully choreographed routine. Air traffic controllers know the location of the planes down to one meter in accuracy. The same can’t be said for space debris. Not all objects in orbit are known, and even those included in databases are not tracked consistently.
An additional problem is that there is no authoritative catalog that accurately lists the orbits of all known space debris. Jah illustrates this with a web-based database that he has developed. It draws on several sources, such as catalogs maintained by the US and Russian governments, to visualize where objects are in space. When he types in an identifier for a particular space object, the database draws a purple line to designate its orbit. Only this doesn’t quite work for a number of objects, such as a Russian rocket body designated in the database as object number 32280. When Jah enters that number, the database draws two purple lines: the US and Russian sources contain two completely different orbits for the same object. Jah says that it is almost impossible to tell which is correct unless a third source of information makes it possible to cross-correlate.
Jah describes himself as a space environmentalist: “I want to make space a place that is safe to operate, that is free and useful for generations to come.” Until that happens, he argues, the space community will continue devolving into a tragedy in which all spaceflight operators are polluting a common resource.
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THE MYTH OF LEARNING STYLES
The idea that teaching methods should match a student’s particular learning style — their personal way of learning — is popular with teachers and students alike. But the evidence suggests it may not be helpful.
The concept of learning styles is one of the most influential — and widely criticized — theories in education. It is the idea that each person finds it easier to learn through a particular method of instruction. Some people, for example, are thought to learn better when they are taught visually; others, when instruction is auditory, or through movement, and so on.
The idea is popular in part because it reflects the intuition of teachers and students. Everyone knows from personal experience that some kinds of learning feel easier than others, and that they may prefer one way of learning over another. And it is also popular because it claims to be based on science. The idea of learning styles was developed in the 1970s, as psychologists and educational theorists were trying to understand how people learn. The idea that different people learn information in different ways was appealing, and it soon became clear that many people had strong preferences about how they liked information to be presented. In a typical research study, one group of students might be classified as “visual learners”, while another group would be classified as “auditory learners”. All the students would then be asked to learn something, with half the visual learners being taught visually, and half being taught aurally. The auditory learners would also be split into the two groups. If the theory was correct, the visual learners should do better when taught visually, and the auditory learners should do better when taught aurally.
But that’s not what psychologists found. As early as 2004, a review of the evidence by cognitive scientists found that the great majority of studies did not provide any evidence supporting the idea that matching the material to a student’s particular learning style was helpful. More recently, a team of psychologists led by Daniel Willingham at the University of Virginia has examined the evidence for learning styles again. They found that the vast majority of studies either found no evidence for the theory, or actually contradicted it. As the researchers point out, people may have preferences about how they learn, but that doesn’t mean that they will learn better when the teaching matches those preferences.
There are several possible explanations for these findings. One is that some students might not actually have a “style” that is strong enough to affect their learning. Another possibility is that students do have preferences about how they learn, but these preferences don’t affect their learning. A third possibility is that students do have preferences, and these preferences do affect their learning, but only because they have learned less well through other methods in the past.
But the most likely explanation is that different ways of learning are useful for learning different things. For example, learning to drive a car involves a mix of visual learning (such as watching the instructor), auditory learning (listening to instructions), and hands-on learning (actually driving the car). In a 2009 article in the journal Psychological Science in the Public Interest, psychologists Harold Pashler, Mark McDaniel, Doug Rohrer and Robert Bjork argued that the learning-styles approach is not only unsupported by science, but may actually be harmful, because it leads teachers to teach students in ways that are not very effective. For example, a student who is a “visual learner” might be encouraged to learn only through visual materials, and never to practice learning by listening, reading or acting.
The idea of learning styles is also harmful because it can give students the impression that they have fixed, or fixed amounts of, intelligence. In recent years, a great deal of research has shown that people’s attitudes to learning can have a large impact on how much they learn. For example, students who believe that intelligence is fixed, and that they are either smart or stupid and there is nothing they can do about it, tend to do less well than students who believe that intelligence can change, and that they can become smarter by working hard at their studies. Similarly, students who have been told that they are “visual learners” might put less effort into tasks that are based on reading or listening. This is particularly worrying because research has shown that students who use a mix of learning methods often learn more effectively than those who stick to their “style”.
Despite the lack of evidence for learning styles, the idea is still very popular. A 2014 study of more than 400 teachers in the UK and the Netherlands found that more than 90 percent of them believed that people learn better if they are taught in their preferred learning style, and that the majority of them used learning styles as a method of instruction. In the US, a 2017 survey of more than 300 teachers found that 96 percent of them agreed with the idea of learning styles, and 24 percent of them used it to guide their teaching.
The idea of learning styles is also popular among students. In a 2018 study, researchers asked more than 600 students in the US about their beliefs about learning. They found that 93 percent of them agreed with the idea of learning styles, and that 78 percent of them said that they had a particular learning style.
The evidence is clear: matching teaching to a student’s particular learning style is unlikely to lead to better learning. It may in fact be holding students back.
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