the-BA : Science News Digest

Image of a doner kebab (copyright: istockphoto.com)

In the science news this week: human activity is having a worrying effect on biodiversity, with wildlife populations down by more than a quarter, scientists unravel how shorebirds can make water defy gravity, and why it’s best not to have a doner for your dinner too often…

Over a quarter of the world’s wildlife has been lost since 1970, according to the Living Planet Index compiled by the Zoological Society of London and WWF. The data was compiled using scientific publications and online databases to monitor the fortunes of over 1,400 species of fish, amphibians, reptiles, birds and mammals.

Freshwater populations were among the worst affected, seeing numbers decline by 29 per cent, while marine species have decreased by 28 per cent and populations of land-based species have dropped by 25 per cent.

The figures were released in advance of a meeting of the Convention of Biodiversity. In 2002, states signed up to the convention pledged to achieve a ‘significant reduction’ in the current rate of biodiversity loss. However, the Zoological Society said that the policies necessary to achieve the 2010 targets had not been put in place by governments, although the decline of species did appear to have flattened off in recent years.

‘The fact that human activities have caused more rapid changes in biodiversity in the last 50 years than at any other time in human history should concern us all,’ the UK’s Biodiversity Minister, Joan Ruddock, told BBC News. She said the report showed that the international community needed to work together to stem the decline.
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In further bad news for the world’s wildlife, a major international study undertaken by scientists – including those on the UN’s intergovernmental panel on climate change (IPCC) – has found that climate change is already having a major effect on the population and behaviour of animal and plant species. 90 per cent of changes could only be explained by global warming, reported the Guardian. The study also found that 95 per cent of environmental effects such as surging rivers, retreating glaciers and shifting forests were also attributable to rising temperatures.

The researchers, whose work was published in Nature, analysed extensive numbers of reports that highlighted behavioural and population changes of 28,800 species, as well as environmental damage and disruption. They then compared historical records to see what changes might be due to natural variations in local climate, deforestation and land use.

Most of the reports analysed were from the period 1970 to 2004, in which time global average temperatures rose by around 0.6 degrees Celsius. In comparison, the latest IPCC report predicts that temperatures could rise by between two and six degrees by the end of the century.

Lead author Cynthia Rosenzweig, Head of the Nasa Goddard Institute for Space Studies climate impact group in New York, said: ‘When you look at a map of the world and see where these changes are already happening, and how many species and systems are already responding to climate change after only a 0.6 degree Celsius rise, it just heightens our concerns for the future. It’s clear we have to adapt to climate change as well as try to mitigate it. It’s real and it’s happening now.’
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According to a US study, exposure to small particulates caused by traffic pollution can increase the risk of developing deep vein thrombosis (DVT). The blood clots that form in the legs can be potentially deadly if they travel to the lungs.

The risk of DVT is known to be high among people that spend a long time without moving – long haul flight passengers are vunerable, as are office workers who spend a long time sitting at their desk without taking time to walk around or exercise. The new research looked at 2,000 people living in Italy (900 of whom developed DVT) and pollution readings from the areas they lived. It found that the risk of developing DVT rose by 70 per cent for every 10 microgrammes per square metre increase in small particulates. The Harvard School of Public Health researchers reported that the pollution made the blood more sticky and likely to clot.

Dr Andrea Baccarelli, who lead the Archives of Internal Medicine report, said their findings ‘give further substance to the call for tighter standards and continued efforts aimed at reducing the impact of urban air pollutants on human health’.
(BBC News)
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Sloths aren’t quite as lazy as popularly believed, according to new research. Sloths in captivity have been reported to sleep 16 hours a day, in comparison a study of wild sloths has found that they doze for only 9.6 hours a day. The work is part of efforts to reveal traits that predict whether an animal sleeps more than another species, which might help shed light on human sleep disorders, reported BBC News.

Three female brown-throated three-toed sloths were caught in the rainforest of Panama, and fitted with a sleep-monitoring device and data recorder before being released. When they were recaptured several days later, their average snooze time was calculated from logged data.

Lead researcher Niels Rattenburg, of the Max Planck Institute for Ornithology in Germany, commented that the creatures ‘may still be sloth-like in terms of their speed of movement but... they don’t seem to sleep an inordinate amount of time’. He said it was the first study to demonstrate that it was possible to record sleep in a wild animal and predicted that it would ‘open the door to a whole new age of sleep research on animals sleeping in their natural habitat’.
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Scientists have discovered that the North American phalarope bird is able to make water defy gravity to flow up its beak into its mouth. The Telegraph noted that the feat is even more remarkable since the bird is likely to have beaten scientists to the trick by millions of years – last year a team from the University of Bristol announced that it was the first to make droplets travel up a slope (you can access a video demonstration via the online article).

The shorebird is well known for its unusual feeding behaviour: it spins in circles on the water to create a vortex that pulls small crustaceans to the surface. It then picks up tiny droplets containing its prey in its beak. MIT mathematicians and engineers have now deciphered how, by using a tweezering motion of its long, thin, downward-pointing beak, it is able to propel the droplet into its mouth in a stepwise fashion. They were able to study the process in slow motion using a mechanical model they built of the phalarope beak.

Since the gravity-defying action is made possible by water surface tension, as well as a physical effect known as ‘contact angle hysteresis’ (that normally causes drops to stick to solids), the phalaropes, and around 20 other bird species that use the mechanism, are extremely sensitive to water surface contaminants such as detergents or oil.
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The Phoenix Mars Lander is due to land on May 25th, but it will be a very tense time for those involved in the $420 million (£215 million) mission, according to the Telegraph. ’Putting a spacecraft safely on Mars is hard and risky,’ said Ed Weiler, Associate Administrator for Nasa’s Science Mission Directorate in Washington. ‘Internationally, fewer than half the attempts have succeeded.’

It will be the first spacecraft to land on the Red Planet in four years. It will enter the Martian atmosphere at close to 13,000 mph and need to slow to about 5 mph seven minutes later. It will be the first attempt at a ‘soft landing’ on the planet since the 1976 Viking landers, using rockets to slow its decent in the final 10 seconds as it is too large to land using gas bags like recent missions.
’They are going to be some of the most stressful few minutes of my life,’ said Deputy Mission Assurance Manager at Nasa, Charles Benson. However, he’ll be worrying after the fact: ‘It takes nearly 15 minutes for a signal to get from Mars to Earth. Phoenix will take about seven minutes to get down, so by the time we hear that entry has started, it will already be over.’

The biggest known risk to the mission comes from rocks that could spoil the landing or prevent the solar panels opening. However, reconnaissance images using a High Resolution Imaging Science Experiment (HiRISE) camera have been used to lesson the risk and revealed that it is one of the least rocky areas on all of Mars.

The mission will collect and analyse the first samples of frozen water ever to be taken from another planet, and will also assess whether conditions have ever been favourable for microbial life. Additionally, Phoenix will search for evidence that large oceans once covered the surface, and scientists hope it could finally end arguments about whether there is water on Mars.
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Other news in brief:

Astronomers have discovered that the universe is actually twice as bright as previously thought, because dust is obscuring our view. While it was known that dust could be having an effect, the extent to which it restricts the amount of light that we can see was not realised until now.

‘A lot of conclusions will have to be revised, notably about the evolution of galaxies,’ said Dr Simon Driver from the University of St Andrews. ‘For nearly two decades we’ve argued about whether the light that we see from distant galaxies tells the whole story or not. It doesn’t; in fact only half the energy produced by stars actually reaches our telescopes directly, the rest is blocked by dust grains.’
(The Telegraph)
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Britain’s ‘X-files’ were released by the Ministry of Defence. The first eight of the 160 files were published this week on the National Archives’ website, and cover the period 1978-1987.
(The Independent)
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A group of albino tadpoles have been found in a garden pond in Wales. The rare discovery was reported last month to Froglife’s Wildlife Information Service – a public advice service that encourages people to get involved with amphibian and reptile conservation. Biologists are now carefully monitoring the development of the tadpoles.
(The Telegraph)
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And finally…

A warning to those who enjoy a regular doner kebab after a night out. Food scientists from Hampshire county council who tested a range of popular takeaway foods for their fat, salt and trans fat content, found that the kebabs can contain up to the equivalent of a wine glass of cooking oil.

‘The majority of that fat is saturated, so it’s going to raise your cholesterol and give you thickening of your arteries. If you were eating that meal twice a week on top of your ordinary diet, it’s a ticking time bomb of coronary heart disease. If you eat lots of fruit and vegetables the rest of the time, it’s not going to be a problem. But if you’re eating pie and chips and fried breakfasts as well, you’re heading towards a heart attack within 10 years.’
(The Guardian)