Australasian Science Magazine

By Stephen Luntz

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Heavy Metal Melancholy
Fluoro Lights Need UV Warning
Mollusc Family Tree Rewritten
GPS Successor’s Battery Life Improved
Dolphin Alliances Assist Mating
Vitamin B Fights Stress
Ocean Budget Balanced
Supermarkets Can Bring Emissions Down, Down
Climate Change Threat to Stromatolites
Ocean Ecosystems Swim to Keep Up

Most people listen to music to make themselves feel better, and find that it works, but a subgroup of teenagers find that listening to heavy metal makes them feel worse yet continue to do so repetitively.

“The mp3 revolution means that young people are accessing music more than ever before, and it’s not uncommon for some to listen to music for seven or eight hours a day,” says Dr Katrina McFerran of the Melbourne Conservatorium of Music.

In most cases this is a positive experience, but after surveying 1000 13–18-year-olds and conducting interviews with 50, McFerran found that some listening styles are correlated with depression. “Examples of this are when someone listens to the same song or album of heavy metal music over and over again and doesn’t listen to anything else. They do this to isolate themselves or escape from reality.

“If listening doesn’t make them feel good about themselves, this should ring alarm bells. Alternatively, if parents notice a downturn in their child’s mood after listening to music this is also a cause for showing interest and getting involved.”

McFerran is anxious to avoid the moral panic that certain music promotes mental illness, but thinks repetitive listening may be a warning sign that parents should watch out for.

She is now beginning more in-depth interviews to find out why those teenagers who say their music darkens their mood continue to listen.

Occasional studies have shown links between country music and suicide, or hip hop and depression, but McFerran says these have generally been contradicted by other research.

On the other hand, she says that “metal and depression comes up all the time. It makes sense that people grappling with the issues in songs would listen to them, but the surprising thing is when it makes them feel worse. I want to know why they keep listening.”

The rush to replace incandescent lights with low energy replacements needs to take into account the fact that some fluorescent lights produce dangerous amounts of ultraviolet light, according to an Australian and New Zealand study published in the American Journal of Public Health.

“The shift to fluorescent lighting means people are now being exposed to ultraviolet radiation, which is compounded by increasing urbanisation and workers spending more of their work time in buildings instead of fields or other outside locations,” says Dr Helen Walls of the National Centre for Epidemiology at the Australian National University. “The safe range of light to avoid exposing the eye to potentially damaging ultraviolet radiation is 2000–3500 K and greater than 500 nm. Some fluorescent lights fall outside this safe range.”

Walls estimates that this increased exposure will produce 3000 more cataracts and 7500 cases of the eye condition pterygia each year, a 12% increase.

The problem does not mean we need to go back to energy-guzzling light bulbs. For one thing, many fluorescent lights are safe, particularly those that produce light at longer wavelengths. Furthermore, perspex UV shields can be used to remove the dangerous component of the light.

However, co-author Dr Kelvin Walls, a building code consultant in New Zealand, says that light globes are not routinely labelled in ways that would allow consumers to know whether they need to take precautions.

Walls says the shorter wavelength fluorescent lights assist concentration, and so are often used in workplaces in place of those that are safer and usually considered more pleasant. She would like to see ultraviolet filters made standard so there would be no need to worry whether the globe in use was dangerous.

The study did not extend to other forms of lighting that have been raised as potential UV sources, such as halogen downlights.

Monoplacophorans, a class of limpet-like mollusc, is more closely related to squid and octopus than the gastropods they appear to resemble, according to a report in Nature.

Dr Nerida Wilson of the Australian Museum contributed to the creation of the world’s most extensive database of molluscan DNA. In doing so she included the Monoplacophora, a once very diverse class thought to have become extinct 375 million years ago until live versions were discovered in the 1950s.

While cephalopods are known for their mobility and brainpower, Wilson says that monoplacophorans are “like your average limpet. They’re not very responsive.” Nevertheless, her research reveals that the creatures, which are now usually restricted to very deep water, are “more closely related to the agile and intelligent cephalopods than other limpet-like gastropods”.

Wilson did not attempt to estimate when the monoplacophorans and cephalopods diverged, and says there is a “complex fossil history of what may be their last common ancestor”. She notes that cephalopod shells have been internalised, but can still be seen in examples such as the nautilus.

GPS systems are about to be replaced by the more accurate Alternate Binary-Offset Carrier (AltBOC), but this has drawbacks of its own. However, Dr Nagaraj Shivaramaiah of the Australian Centre for Space Engineering has overcome some of these problems. His work has made him the first Australian winner of the Institute of Navigation’s Parkinson Award for outstanding research.

The modern GPS system is based on 30-year-old designs, and its precision is so limited that mobile phones rely on a combination of GPS and information from other sources. It is also notoriously hard to use indoors. The European Galileo satellite network, as well as China’s navigation system, will use AltBOC instead.

However, while AltBOC’s greater bandwidth provides increased accuracy, it currently requires much more processing power to operate, in some cases causing receivers to use 35 times as much energy as a GPS system – enough to flatten a mobile phone battery disturbingly quickly.

“I targeted the AltBOC signal because any improvements would not only help to lower costs and energy use, but increase positioning accuracy,” Shivaramaiah says. “And that’s all good news for users, especially as gadgets like smart phones become more sophisticated and commonplace.”

Shivaramaiah found it is possible to produce a simpler AltBOC signal that is easier for receivers to process. While the energy required will still be larger than for GPS he says it should be “much lower” than existing AltBOC designs. Moreover, Shivaramaiah’s work, done as part of his PhD, reduces interference when multiple receivers are using the same system nearby.

With a suite of navigation satellites about to be launched, Shivaramaiah says there is no need to change the hardware on board in order to have them transmit using his simpler signal.

The University of NSW owns the patent on Shivaramaiah’s work and is negotiating with the European Space Agency for its use on Galileo.

Male dolphins improve their mating success by forming alliances. Larger groupings work better, but for unknown reasons these groupings are also less common.

Jo Wiszniewski, a Macquarie University PhD student, tested the paternity of bottlenose dolphins off Port Stephens. She found that one group of four males, which she named The Beatles, spent most of their time together and fathered 13 out of 32 young born during the study. Males in groups of three were also successful, while even one ally was better for fatherhood than being a loner.

“These results are fascinating because it demonstrates that male bottlenose dolphins need to cooperate with each other to maximise their reproductive success,” Wiszniewski says. The groups would surround females who were ready to mate and drive off competitors for periods of several weeks.

Wiszniewski says it is not clear whether the males were also using their numbers to force unwilling females. She has not observed cases of females showing signs of trying to get away from a male group, although others have reported this.

Despite The Beatles’ success, four-member male alliances have not been observed in any other studies, although groups of two or three males exist in Western Australia and the United States.

Wiszniewski is unable to answer why larger groups are not more common. “I think alliance formation is quite a complex process,” she says. “They need to tolerate others mating with females. It could also be ecological constraints, as males in larger groups will deplete food resources more quickly.”

Contrary to their nickname, Wiszniewski says all members of The Beatles appear to have similar competitive ability in regard to mate-attraction, and this is probably an essential feature for the formation of alliances. Somewhat surprisingly, alliance members were not particularly likely to be closely related.

Similar alliances have been observed in chimpanzees, but Wiszniewski says they are not common in other animals – probably because they “require high levels of cognitive ability”. To work, she says, “the dolphins need to be aware of third-party relationships – how their alliance partners relate to other males. You don’t want to make an alliance with someone who may cheat on the alliance.”

People with stressful jobs should consider taking Vegemite sandwiches to work, based on a recent study published in Human Psychopharmacology. Prof Con Stough of Swinburne University’s Faculty of Life and Social Sciences reports that vitamin B proved highly beneficial for the mood of those struggling with workplace stress.

Stough gave 60 participants either high dose vitamin B supplements or placebos, and assessed their moods after 30 and 90 days. “At the end of the 3-month period, those in the vitamin B group reported much lower levels of work stress than they did at the beginning of the trial,” Stough says. “In fact, participants experienced an almost 20% improvement in stress levels.” The placebo provided no benefit.

“Vitamin B, which is found in whole unprocessed foods such as meat, beans and wholegrains, is integral to the synthesis of neurotransmitters critical to psychological well-being,” Stough says. “But the reality is that many people don’t get enough vitamin B from their diet, so they are turning to vitamin supplementation.”

Both previous and subsequent research has indicated that vitamin B may be protective against other forms of stress, but Stough says: “Workplace stress has not been studied a lot”.

Nevertheless, study sponsor Blackmores has a successful product line known as Executive Stress B formula, which Stough used in the study. While the tablets contain vitamins outside the B family, Stough says any psychological benefits are likely to be from B vitamins, with folate his prime candidate, although vitamin B12 is known to counter brain shrinkage and vitamin B6 is a precursor to dopamine and serotonin.

“It’s a very small study,” Stough says. “We want to do a larger one, including blood tests for individual vitamins.”

Three-quarters of Stoughs’ subjects were in full-time work, averaging 46 hours a week. “We think they took part because they felt under pressure at work,” he says.

Stress was measured using a standard questionnaire measuring various sorts of psychological and interpersonal strain. The study focused on stress caused by workplace factors.

While those on the placebo produced highly consistent results throughout, those taking vitamin B experienced lower anger and increased energy within 4 weeks, while anxiety levels had fallen significantly by the 12-week mark.

The discrepancy between the rise in sea levels observed over the past four decades and the estimated contribution from various causes has been resolved. Dr John Church of CSIRO’s Wealth from Oceans Flagship has led an international team that drew on new data and analysis to estimate the contribution to sea levels since 1961 of the thermal expansion of the oceans, melting of glaciers and ice caps, Greenland’s and Antarctica’s ice sheets, and altered use of water on land.

The Intergovernmental Panel on Climate Change’s fourth report notes that sea level has been rising 1.8 mm/year since the 1960s. However, a sum of the estimated contributing factors came to just 1.1 mm/year. The discrepancy was troubling, indicating that we might know less about the climate system than we thought.

“We revisited the Earth’s sea level and energy budgets together using new and updated estimates of all contributing factors for the past few decades, and including a new estimate of groundwater depletion,” Church says. “This allowed us to balance the sea level budget from 1972 to the present.”

Church and his colleagues reported in Geophysical Research Letters that the problem was not that any single factor was drastically wrong. Instead, they found that since 1972 the upper 700 metres of the oceans have warmed slightly more than had been recognised.

Moreover, previous estimates ignored the lower ocean depths as this was too hard to calculate. Estimates are now possible, and make a small contribution to the rise.

In combination with revised estimates for net changes to groundwater, glacier melt and changes at the poles, Church and his colleagues produced estimates that precisely match the observations since 1972. Over this period, thermal expansion of the oceans accounts for 40% of the observed rise, while the melting of non-polar ice represents 35%.

Mystery remains over the rise observed in the 1960s, which is substantially larger than the sum of estimates of the contributing factors.

The analysis of ocean temperatures, which allowed the team to recalculate thermal expansion, also enabled them to estimate how much energy has been stored beneath the waves in the process. They conclude that 90% of the extra energy that the Earth has absorbed since 1972 as a result of increased greenhouse gases is stored in the oceans, leading to warmer waters.

From these results Church says it is also possible to infer the contributions that aerosols have made to cooling the planet, and therefore estimate emissions over the past 40 years – something that was hard to assess accurately prior to satellite monitoring.

Church says that it will now be possible to compare these more accurate estimates of individual components with predictions made by climate change models, improving the accuracy of these models in the process.

Commercial refrigeration and air conditioning units are notorious electricity hogs, but businesses such as supermarkets can save on emissions by remanufacturing compressors when they wear out rather than buying new ones.

A/Prof Michele Rosano and Dr Wahidul Biswas of the Curtin University Centre for Excellence in Cleaner Production conducted an analysis of the energy that goes into producing the large compressors used in supermarkets. Allowing for the mining, processing and manufacturing involved, they found that production of a typical unit releases 1590 kg of CO2.

However, the process of fixing a cracked cylinder head, fractured crank shaft or worn bearings emits just 120 kg, even allowing for the cleaning and washing, reassembling and testing that is required.

“Coles supermarkets uses around 7500 compressors in their stores, with an average size of 27 kW. Through our analysis, we determined that remanufactured compressors produce about 89–93% less greenhouse gas emissions than those associated with a new OEM compressor,” Rosano says. “If these compressors were completely replaced with remanufactured compressors, 19,500 tonnes of CO2 emissions could be avoided.”

Biswas says that while equivalent analysis has not been done on the smaller units used in household fridges and air conditioners, the proportional savings would be similar. He notes, however, that remanufacturing is currently rare.

Rosano and Biswas suggest that for companies keen to reduce their carbon tax costs, a shift to remanufacturing rather than replacement could be a could place to start.

For three billion years they have survived ice ages and meteor strikes, but humans may yet destroy the stromatolites of Shark Bay in Western Australia.

The ancient structures of blue-green algae now only flourish in environments so saline that animals cannot feed on them, the most famous of which is Hamelin Pool in Shark Bay. The area was World Heritage listed for this reason. However, the listing itself cannot keep the climate in check.

“The Wooramel River, which flows into Hamelin Pool, has flooded three times in the past year, washing in a huge amount of sediment and damaging Shark Bay’s seagrass meadows,” says Em/Prof Diana Walker of the University of Western Australia’s Oceans Institute. “Usually the river only floods every 8 years or so.”

The floods are a result of cyclones coming unusually far south, a predicted consequence of climate change. Temperatures within the bay have surged, with recordings as high as 38°C last summer rather than the usual 32°C.

The flooding directly affects the whole ecosystem, temporarily reducing the area’s salinity and interfering with the calcium-rich groundwater upwelling on which the stromatolites depend.

However, the most serious impacts are on the pool’s seagrasses. The seagrasses are damaged by sediment brought down in the flood, with the impact increased by the high temperatures and reduced salinity associated with flooding events.

Over the millennia the seagrasses have built up the sandbank known as the Fauré Sill, which makes Shark Bay suitable habitat for stromatolites. It prevents water in the pool mixing with the wider ocean, sustaining the hypersaline conditions.

“We’ve looked at growth rates and shoot lengths of seagrasses buried by sediment, and we know that they are significantly affected,” says Prof Gary Kendrick.

One area of the Sill has a large patch of defoliated seagrasses after the floods. If the plants do not recover quickly they may lose the capacity to hold the sandbank together, with catastrophic consequences for the stromatolites. Sea level rise could also overwhelm the sandbank.

Walker says that Shark Bay is relatively immune to more local human action. “The glorious thing about the bay is how rich the biodiversity is and how little damage we do. Of course, Hamelin Pool is WA’s only marine nature reserve, but the bay has been good at looking after itself.”

However, Walker fears this will not apply to repeated cyclonic events. She says that if this continues to be an issue, the WA Department of Conservation “needs to work out ways to put in holding ponds so the sediment doesn’t hit at one time”.

As the planet warms, many species will find that their habitable temperature range is no longer where it once was, forcing a shift to cooler zones. Now an international study with a large Australian contribution has found that marine life is being affected in unexpected ways.

Published in Science, the study explores the speed with which temperature regions have moved over the past 50 years.

Increases in greenhouse gases have most impact at the poles, but Prof Carlos Duarte of the University of Western Australia’s Oceans Institute says that when it comes to measuring the distances that isotherms have shifted, “the velocity of climate change is much faster in the Northern Hemisphere, and is particularly fast in the marine region north of Australia as well as the nation’s east coast. Climate change is slow in the marine region south of Australia and moderate off the west coast.”

Prof John Pandolfi of the University of Queensland says that this has occurred because “at the Equator, temperatures are so uniform you often have to move a very long way to track a small change”.

Similarly, while the oceans are warming more slowly than land, some marine isotherms are moving faster than nearby terrestrial equivalents. Pandolfi says this is particularly the case in equatorial and subarctic regions.

Disturbingly, the Coral Triangle, the most biologically diverse marine region, is experiencing rapid temperature shifts. An optimistic view would have this diversity pouring down into northern Australia and the Great Barrier Reef, but corals lack the capacity to move rapidly and Pandolfi notes that many species, on running into northern Australia, might need to shift a very long way east or west to continue their quest for cooler waters. The problem is even more intense in the Mediterranean Sea.

Deeper waters are warming far more slowly, but Pandolfi notes: “A lot of the productivity is at the surface. Change that and other things are affected.

“As seas around the Equator warm more quickly and sea life migrates away – north or south – in search of cooler water, it isn’t clear what, if anything, will replace it. No communities of organisms from even warmer regions currently exist to replace those moving out.”