IELTSwithJurabek

You should spend about 20 minutes on Questions 14-26, which are based on Reading Passage 2 on pages 6 and 7.

The importance of icebergs to ocean life

A The word iceberg refers to pieces of ice larger than five meters across. The waters surrounding Antarctica are home to most of the icebergs on Earth, although they can also be found in the Arctic region. The water surrounding icebergs teems with life including a range of fish and, consequently, the seals which prey on them. Seabirds such as gulls, fulmars and other birds often visit as well. Some fishermen in Arctic regions claim that the fishing is often best in the immediate vicinity of icebergs. Recent research is beginning to shed light on what it is about icebergs that is attractive to wildlife.

B Ken Smith, senior scientist at the Monterey Bay Aquarium Research Institute, explains that 'free-drifting icebergs are hot spots of chemical and biological enrichment.' His studies in the Weddell Sea off Antarctica confirmed high concentrations of chlorophyll, krill, and seabirds in the water surrounding the icebergs he sampled, extending out to about two miles around each berg. While he wouldn't speculate about whether the same results would be found around Arctic icebergs, other scientists say that the evidence suggests it may well be the case.

C During their first expedition, Smith and his research team deployed a series of oceanographic instruments, fishing nets, and video cameras attached to remotely operated vehicles around a small iceberg with a surface area of 0.12 square kilometers, as well as around another much larger example. Their results revealed how important icebergs are to the marine environment.

D Perhaps their most significant finding was that as icebergs melt, accumulated dust, pulverized rocks, and other terrestrial materials are dispersed into the water. These were all incorporated into the ice millions of years ago when it was part of glaciers which scraped up debris from the surface of the soil while moving across huge areas of land. Once in the water, these materials act as ocean fertilizer to nourish microscopic marine organisms such as plankton, upon which the entire food chain ultimately depends. 'These icebergs can be compared to river estuaries that supply surrounding coastal regions with nutrients as they enter the ocean,' Smith and his team wrote.

E Oceanographer Greg Stone had a more hands-on approach to studying the productivity around icebergs. A vice president at Conservation International, one of the world's largest biodiversity conservation organizations, he led a team of scuba divers and scientists on a rare and dangerous expedition to study iceberg ecology around B-15, the largest iceberg ever known, which broke away from the Ross Ice Shelf in Antarctica in 2000. Nearly the size of the US state of Connecticut and containing enough fresh water to supply the entire US for five years, the berg had begun to break up by the time Stone's team arrived several months later, and the shifting pack ice made it impossible for them to reach it. But Stone and his colleagues still conducted about ninety dives around icebergs of various sizes. What they found was an unexpected bonanza of marine life in and around the ice.

F Greg Stone noted that the water of Antarctica where his team undertook dives was several degrees below freezing. Like Smith's team, they recorded higher concentrations of jellyfish and krill within a mile or so around the icebergs. They also frequently saw juvenile ice fish living in burrows in the ice, though they were uncertain whether the fish excavated these themselves to hide from predators or simply took advantage of natural features of the ice. In an especially dangerous dive, they swam 300 meters into a cave inside another iceberg that had been grounded for several years and found a spectacular garden of invertebrates - feather duster worms, starfish, colorful sponges, sea cucumbers, and more - living on the seafloor at the farthest reaches of the cave.

G According to Stone, most Antarctic icebergs get pushed around continuously by the wind and currents. As they move, their keel will rub along the seafloor, disturbing the benthic ecosystem. But because this particular iceberg had been grounded for several years, it served to protect bottom-dwelling creatures from the ravages of moving icebergs and nurtured this underwater garden.

H Stone agrees with Smith's conclusion that the big picture of iceberg ecology is the vital role they play in fertilizing the Southern Ocean, thereby creating the largest biomass on Earth. 'The whole food chain gets fired up around one of these things,' Stone explains. 'The ice is the biological engine that drives the ecosystem, fueled further by the Antarctic's twenty-four-hour summer sunshine. There's no doubt that if you're an ocean animal, you're going to be attracted to an iceberg because it's generally a better place to be.'

I If you're not an ocean animal, on the other hand, it's probably best to keep your distance from icebergs, because one thing they are not is safe. Just hours after Stone's dive team emerged from exploring the cave within the grounded iceberg, the entire berg completely crumbled and disintegrated, leaving in its place what Stone described as 'two square miles of shattered crystal'. The pressures caused by the continuous melting and re-freezing of water throughout these mountainous structures ultimately lead to their destruction. As frightening as it was to Stone and his team of scientists, who decided then and there never to dive in an iceberg cave again, it also may have been the first time anyone had witnessed such an event.

You should spend about 20 minutes on Questions 27-40, which are based on Reading Passage 3 on pages 10 and 11.

The Dunedin study

The New Zealand city of Dunedin in the early 1970s can easily be made to sound idyllic. There was next to no unemployment and people left their doors unlocked at night. New Zealand was then the ninth richest country in the world and many residents believed that, as a place to bring up children, this was a city without rival. However, Phil Silva, an educational psychologist, was not so certain and decided to take a closer look. Silva identified those children born in the year from April 1, 1972 whose mothers were still living in the city three years later. The parents were asked if they would mind bringing their children in for a health and development assessment. Incredibly, no fewer than 91% agreed to help and 1037 three-year-olds completed half a day of tests and experiments. In the process, the Dunedin Multidisciplinary Health and Development Study was born.

There was precious little money at Silva's disposal, so the assessments were done in a church with the help of dozens of volunteers. Each child was assessed against a range of measures such as height, weight, and head circumference. Language skills were assessed and profiles of behaviour were compiled. However, one set of assessments was never going to satisfy Silva's curiosity, so when the children were five, his same team asked the parents to bring the children back for a second study. Of the original 1037 children, 96% came. The data gathered at age three was updated and new measurement criteria - discipline, nutrition, dental health - were introduced.

By 1978, Silva was able to shock the nation with his findings: one in four children had delayed language development; 15% had ear problems; the researchers had identified one child who was blind and another who might have died from undetected skin cancer. New Zealanders, Silva declared, were more diligent about their cars than their children. Cars were required by law to be regularly checked; if children were treated similarly, ideally at behavioural clinics in schools, problems could be picked up in time to prevent lasting damage.

The parents were asked to bring their children back at ages seven, nine and 11 to the old church for further assessments. Crucially for the study's survival, the politicians were finally starting to take note and government funding began to trickle in. By the time the children returned at age 13, the study had taken up residence in an abandoned building tucked behind the dental school. It wouldn't have been the researchers' first choice, and was certainly not grand, but it was at least a site for the long term and its acquisition represented a landmark in the study's development. It was to this building that the participants returned at ages 15, 18, 21, 26 and, most recently, at 32.

Among the most recent findings are that birth complications - a focus of Silva's original research - don't necessarily set children up for problems as they mature in later life, although the amount a newborn infant weighs is associated with IQ. Paediatric textbooks had insisted for years that breast-feeding protected against medical problems like asthma and allergies. The Dunedin study has shown that assumption to be incorrect. Other findings that challenged the received wisdom include the fact that thumb-sucking does no harm; birth order makes no difference to later development; and pre-schoolers whose mothers work are not disadvantaged. Overall, the study has confirmed the notion that broad personality traits are laid down by the age of three. Along the way, the Dunedin researchers have been able to contradict old assumptions and explode medical myths long held by the profession.

The Dunedin study is important not only because of its findings, however. It also provides a model because of the extraordinary commitment of study members. No other longitudinal research project in the world matches its retention rate of 96% at age 32. Silva concedes that luck has a lot to do with this: Dunedin city was, and largely still is, close-knit, homogeneous and devoted to its university and medical school. It is large enough to produce a study population that produces findings that can be generalised to New Zealand and other developed countries, yet small enough that one in every 10 households has had a child or relative in the study.

More important than circumstance, though, was the approach taken by the researchers. Silva recalls that by year 13, participation had dropped off - only 82% came in for assessments. He realised the most important asset they had was the sample group and these people must be nurtured at all costs. He spent many long hours out in the field, finding those participants who had gone adrift and persuading them to come in. Study members are kept up to date with the steady flow of findings to which they have contributed. Privacy is absolutely paramount: Silva won't even say how many of the study members are now in prison: nothing must erode the trust that's been built up over the years.

Today, more than a quarter of the sample live overseas so the study also has its own travel agent, who does her best to accommodate requests to spend Christmas in Dunedin with family. This is just one example of the enormous effort that goes into maintaining contact and removing obstacles to participation. With such diligence and care, researchers hope the Dunedin study will continue for many years, perhaps generations, to come.