Magnets disrupt crocodile radar

Magnets disrupt the homing ability of potentially lethal crocodiles

Magnets are being attached to crocodiles in Florida to disrupt their sense of direction and so make them less of a threat to humans.

Crocodiles use the influence of the earth's magnetic field to help them navigate, according to researchers.

Attaching magnets to a crocodile's head seems to disrupt its "homing" ability.

The technique is now being tried as part of an attempt to make streets safer in places near crocodile habitats such as the Everglades.

Crocodiles are extremely territorial. Simply moving them away from urban areas doesn't lessen the risk to humans. Some of the giant reptiles have been found to travel "home" at the rate of 10 miles per week.

But in an experiment now taking place in Florida, conservation officials have moved crocodiles deeper into the swamps and then released them after taping magnets to their heads.

"We put the magnets on when they're captured," said Lindsey Hord, of the Florida Fish and Wildlife Conservation Commission, "and since they don't know where we take them, they're lost."

'Unique and valuable'

Experiments with crocodiles and magnets were first carried out at the Crocodile Museum, in Chiapas, in Mexico.

Scientists there say they have used the technique to re-locate 20 crocodiles over the past few years.

The crocodile was once an endangered species in the United States, but conservation efforts in Florida mean that numbers are increasing and there are now believed to be nearly 2,000 of them.

"Crocodiles are unique and valuable creatures," said Lindsey Hord, "and we feel like we have a responsibility to live with these animals as much as we can."

Earliest 'human footprints' found

Laser scanning was used to plot the exact dimensions of the prints

The earliest footprints showing evidence of modern human foot anatomy and gait have been unearthed in Kenya.

The 1.5 million-year-old footprints show signs of a pronounced arch and short, aligned toes, in contrast to older footprints.

The size and spacing of the Kenyan footprint trails - attributed to Homo erectus - reflect the height, weight, and walking style of modern humans.

The findings have been published in the journal Science.

The footprints are not the oldest belonging to a member of the human lineage. That title belongs to the 3.7 million-year-old Australopithecus afarensis prints found in Laetoli, Tanzania in 1978.

Those prints, however, showed comparatively flat feet and a significantly higher angle between the big toe and the other toes, representative of a foot still adapted to grasping.

Exactly how that more ape-like foot developed into its modern version has remained unclear.

The fossil record is distinctly lacking in foot and hand bones, according to lead author Matthew Bennett of Bournemouth University, UK.

"The reason is that carnivores like to eat hands and feet," Professor Bennett told BBC News.

"Once the flesh is gone there's a lot of little bones that don't get preserved, so we know very little about the evolution of hands and feet on our ancestors."

The footprints were found near Ileret in northern Kenya. The site, on a small hill, is made up of metres of sediment which the researchers carefully cleared away.

What they found was two sets of footprints, one five metres deeper than the other, separated by sand, silt, and volcanic ash.

The team dated the surrounding sediment by comparing it with well-known radioisotope-dated samples from the region, finding that the two layers of prints were made at least 10,000 years apart.

Another critical feature that the series of footprints makes clear is how Homo erectus walked.

There is evidence of a heavy landing on the heel with weight transferred along the outer edge of the foot, progressing to the ball of the foot and lifting off with the toes.

"That's very diagnostic of the modern style of walking, and the Laetoli prints don't give that same character," Professor Bennett said.

The finding is a critical clue for mapping out the evolution of modern humans, both in terms of physiology and also how H. erectus fared in its environment.

H. erectus was a great leap in evolution, showing increased variety of diet and of habitat, and was the first Homo species to make the journey out of Africa.

"There's some suggestion out there that Homo erectus was able to scour the landscape for carcasses and meat...and was able to get there very quickly, had longer limbs and was much more efficient in terms of long distance travel," Professor Bennett added.

"Now we're also saying it had an essentially modern foot anatomy and function, which also adds to that story."

More seeds for 'doomsday vault'

The remote, frozen landscape provides an ideal backdrop for the vault

Almost 90,000 food crop seed samples have arrived at the "doomsday vault" in the Arctic Circle, as part of its first anniversary celebrations.

The four-tonne shipment takes the number of seeds stored in the frozen repository to more than 20 million.

The Svalbard Global Seed Vault, built 130m (426ft) inside a mountain, aims to protect the world's food crop species against natural and human disasters.

The

Polar Year 'hailed as a success'

The Princess Elisabeth Station in Antarctica was entirely built during the IPY

Scientists and policymakers marked the official end of the International Polar Year (IPY) Wednesday at the World Meteorological Organization in Geneva.

The 60-country, $1.2bn (

Aphids' sticky suicide missions

Advertisement

Aphids' sacrificial home defence

An aphid species has "soldiers" who often die in the process of repairing damage to galls, the homes that aphids force their plant hosts to grow.

The aphids crowd around a hole in the gall and squeeze out a fluid comprising two-thirds of their body size, using their legs to mix it and form a "scab".

Full recovery of the plant tissue was only possible with the presence of the aphids after the scab formed.

The work is published in the journal Proceedings of the Royal Society B.

Many of the soldier aphids, of the species Nipponaphis monzeni, die from the significant loss of body mass.

Many others get stuck in the viscous fluid and fail to escape. Like workers on the Great Wall of China, they simply become a physical part of the building work.

The aphids' self-sacrifice was first noted by Utako Kurosu of the Tokyo University of Agriculture in 2003, who called it "the most elaborate social behaviour so far known among aphids".

It's an interesting evolved set of behaviours and physiologies that are closely linked, that have co-evolved Peter Smithers, University of Plymouth

What remained unclear was the fate of the galls after N. monzeni's emergency repair mission.

As a living part of the plant and a food source for the growing aphids, the gall's survival is tied to that of the creatures, which mature and escape fully grown in the autumn.

Co-evolution?

Takema Fukatsu of the University of Tokyo and colleagues followed the progress of a number of damaged galls after the short-term fluid fix was performed.

The team found that the galls that were left unpatched were significantly more likely to die.

Moreover, the soldier aphids' efforts didn't stop at simply plugging the gap; they tended to cluster around the damaged area for weeks afterwards.

"After the hole is plugged by solidified body fluid, soldier nymphs manipulate the growth and regeneration of plant tissue nearby the breach in an intricate manner, which leads to complete sealing of the hole by plant tissue," Dr Fukatsu told BBC News.

Even 13 days after damage, soldiers(white) crowd around the healing hole

When aphids inside the gall were prevented from clustering around the damage after the initial fix, the regeneration did not occur.

Dr Fukatsu says the evolutionary path that has led to the repair behaviour is hard to unpick, because N. monzeni is the first species to be observed exhibiting it.

Research is currently underway to understand the mechanism by which the soldiers' body fluid forms the patches; Dr Fukatsu says that the fluid contains several molecules that are involved in the clotting when insects themselves get injured.

"Once the gall is actually growing with the aphids inside, you'd think it'd be in the plant's interest not to help them out," said Peter Smithers, an entomologist at the University of Plymouth.

"This is the aphids fooling the plant into doing something that it doesn't need or want to do. It's an interesting evolved set of behaviours and physiologies that are closely linked, that have co-evolved.

"But the aphids are calling the shots."

Getting an appetite for biotechnology

VIEWPOINT Jorgo Chatzimarkakis

A growing population and climate change is going to make it difficult to meet the demand for food in the coming years, says German MEP Jorgo Chatzimarkakis. In this week's Green Room, he argues that we must embrace the solutions offered by biotechnology if we are going to feed the planet.

Crops for the food production... and GM crops for industrial use should be strictly separated

In 2050, according to estimates, there will be nine billion mouths to feed around the world who will demand high quality, nutritious food.

Yet we will not be able to sustain a growing population if we do not amend our methods of agricultural production to reflect the new challenges before us.

We should stop our ideological debates and start thinking about how to strengthen the security and sustainability of global food production.

The application of advanced genetic science in breeding new crop varieties, including genetic modification methods, cannot alone address these massive challenges but it can be a significant part of the solution.

One way to enhance global food production is the use of Marked Assisted Selection (MAS), which allows the improvement of crops through "smart breeding".

This involves the crossbreeding of plants of similar families, rather than their genetic modification through the integration of foreign genes.

The application of genetic modification methods would be an additional alternative in the development of energy-rich and environmentally safe biomass for industrial use.

However, crops for the food production based on the MAS technique and GM crops for industrial use should be strictly separated.

Unfortunately, in Europe, we are lacking an open and balanced debate on the contribution that modern agriculture technologies could make to help farmers face today's challenges.

Lightening the load

The EU has set ambitious targets to tackle climate change, setting its member states the goal of cutting emissions by 20% (possibly 30%) from 1990 levels by 2020.

GM crops used today have been produced to reduce the need for tillage or ploughing, allowing farmers to adopt conservation or 'no-till' farming practices

Agricultural practices - such as ploughing, deforestation, cattle and fertiliser use - currently account for about 25% of greenhouse gas emissions, making it more important than ever to curb emissions from this sector.

Agricultural biotechnology can help by reducing the production of greenhouse gases, helping crops adapt to varied and often adverse environments, and by helping to increase yields while using fewer hectares of land and other inputs.

For example, GM insect resistant crops have been developed so that farmers can apply significantly fewer insecticide treatments.

This consequently leads to a reduction of fuel used by farmers when they spray pesticides on their fields, which means a saving in carbon dioxide emissions.

Additionally, GM crops used today have been produced to reduce the need for tillage or ploughing, allowing farmers to adopt conservation or "no-till" farming practices.

This has positive consequences in terms of mitigation:

tractor fuel use for tillage is reduced

soil quality is enhanced and levels of soil erosion are cut

less tillage keeps carbon in the soil, leading to lower emissions

The application of genetic technology to make plants better equipped to deal with a changing and difficult climate is one of the most exciting and important areas of advance in biotechnology.

Developing nations are already struggling to grow enough food

Water shortages are already costing billions of dollars a year in crop shortfalls around the world, and are likely to grow more costly.

The preservation of our water resources is key as climate change increases the risk of water shortages and desertification.

GM crops have already been developed to be better adapted to warmer conditions.

Herbicide-tolerant soya, maize, cotton and oilseed rape have allowed farmers to reduce the amount of ploughing required before planting their crop, thereby reducing water dissipation.

They also help to reduce fossil fuel use, carbon emissions and soil erosion. New varieties of drought resistant crops, or crops which can be grown on marginal lands, also offer new opportunities to some of the world's poorest regions.

Research into drought tolerant crops, such as "water efficient maize" produced by the African Agricultural Technology Foundation (AATF), a public-private research partnership based in Nairobi, suggests that yields can be maintained in water depleted situations.

There are also a number of projects being developed to optimise the nitrogen use of a crop, a vital requirement in many parts of the world where nitrogen fertilisers are in short supply.

Recognising that the production of fertilisers is energy demanding, these traits will be as beneficial to Europe, as they are to Africa.

Reasoned debate

In its annual study, the International Service for the Acquisition of Agri-Biotech Applications (ISAAA) found that 13.3 million farmers in 25 countries planted 125 million hectares of biotech crops during 2008.

Climate change is projected to result in more extreme weather events

It is clear that, when given the choice, farmers choose to benefit from the potential that GM offers.

The vast majority of farmers benefitting from GM technology are resource poor, frequently with small plots of land and limited technology to assist their farming.

In the past year, countries such as Egypt and Burkina Faso have embraced GM technology in recognition of the benefits they provide to both productivity and sustainability.

But we should not forget the sensitivity of the issue for European consumers. We therefore need strict transparency and control in order to allow consumers choice.

However, only one GM crop has been approved for cultivation in Europe in the past 10 years.

As the challenges we face become more acute, there has never been a better time for a genuine discussion about the benefits of biotechnology, smart breeding and GM crops for industrial use.

Dr Jorgo Chatzimarkakis is a German MEP and a member of the European Parliament's Committee on Agriculture and Rural Development

The Green Room is a series of opinion articles on environmental topics running weekly on the BBC News website

---

Do you agree with Dr Jorgo Chatzimarkakis? Does biotechnology have a key role to play in terms of helping the world feed itself? Will the advances help improve food security for billions of people? Or do we just need to become more efficient in the way we produce food?

Send us your comments using the form below:

Name

Your e-mail address

Town/city and country

Your comment

The BBC may edit your comments and not all emails will be published. Your comments may be published on any BBC media worldwide.

Terms & Conditions

Diary: New Guinea's secret species

The team is filming in the little-explored forests of New Guinea

An international team of explorers and scientists is on an expedition to the forbidding jungles of New Guinea.

They plan to survey a lost world of volcanoes, caves, mountains and rivers in search of the strangest animals on the planet.

They will have to endure one of the toughest jungles on Earth to step where no scientist has set foot before.

A successful expedition could result in this unique forest being safeguarded forever.

In this weekly diary, the BBC Natural History Unit crew accompanying the researchers will share their adventures.

MONDAY 23 FEBRUARY - LOST WORLD

Twelve months of planning came to a head this week as we finally ventured into the heart of Mount Bosavi.

Helicopter flies the explorers into the centre of the volcano

An extinct volcano blanketed by thick jungle, Bosavi has steep fortress like cliffs protecting a four-kilometre wide crater at it's centre.

We managed to find a weather window and land a helicopter inside.

No outsiders have spent time in this lost world, no scientists have ever been here, and even the scattered local population rarely enter the crater. We all felt this was a truly original exploration.

The crater is paradise found. We are camped next to a crystal clear, fast flowing river, whose water we bathe in, swim in and drink - all at the same time.

Surrounded by pristine rainforests, there are no signs of human life apart from our own and every rock is draped with green moss.

Up close and personal with a tree kangaroo

In this Eden animals are completely na

Malfunction hits Nasa CO2 sat

The mission was designed to monitor global carbon dioxide levels from space

Nasa's first mission designed to measure carbon dioxide (CO2) from space has suffered a rocket malfunction.

Officials said that the fairing - the part of the rocket which covers the satellite on top of the rocket - failed to separate properly.

If the finding is confirmed, the mission would be lost.

The Orbiting Carbon Observatory (OCO) was intended to help pinpoint the key locations on our planet's surface where the gas is being emitted and absorbed.

Lift-off for Nasa's 'CO2 hunter'

By Jonathan Amos Science reporter, BBC News

OCO will launch from California

Nasa has launched its first mission dedicated to measuring carbon dioxide (CO2) from space.

The Orbiting Carbon Observatory (OCO) will help pinpoint the key locations on our planet's surface where the gas is being emitted and absorbed.

CO2's increased concentration in the atmosphere will lead to global climate change, say the major institutions and agencies that study Earth sciences.

The OCO data is intended to help forecast that change more accurately.

Currently, carbon dioxide is regularly sampled at about a hundred sites around the world. The new satellite will be taking roughly 30,000 readings on each orbit.

"We need to make a measurement that is about three times more precise than has ever been made for a trace gas in the Earth's atmosphere," said Dr David Crisp, OCO's principal investigator.

"We regularly measure ozone in the Earth's atmosphere to about 1%. We need to make a measurement of CO2 to about three-tenths of 1% to start answering the questions that face scientists."

Colour clues

The $270m mission was launched by the smallest ground-launched rocket currently in use by the US space agency.

NASA'S OCO MISSION OCO weighs approximately 440kg Will fly at a 705km altitude Passes the equator every pm 30,000 measurements per orbit Global coverage in 16 days

The Taurus XL vehicle left the Vandenberg Air Force Base in California at 0951 GMT, Tuesday.

It lofted OCO into a near-polar orbit at an altitude of 705km (438 miles). The spacecraft will circle the planet once every 98.8 minutes, passing over the entire globe in the course of 16 days.

Nasa stresses the mission is an experimental one; it first has to establish that the measurement approach it has adopted is a robust one.

OCO carries a spectrometer that analyses the sunlight reflected off the Earth's surface. By splitting that light into its component colours, it will be able to see the part of the spectrum absorbed by carbon dioxide molecules.

By measuring oxygen's presence in the atmosphere also, OCO should be able to arrive at a concentration figure for CO2. The instrument is sensitive to carbon dioxide in the lower reaches of the atmosphere.

"We'll be pumping down about 50 gigabits of data every day," said Dr Crisp.

"We're a very small spacecraft - we'd be a very cosy telephone booth - but we'll pump down data at such a high rate I often joke we'll melt the snow around the base of the down-link station."

CO2 in the atmosphere has seen a steady rise in recent years

This mass of information should help the OCO science team pinpoint the so-called sources (where CO2 comes from) and sinks (where CO2 is pulled out of the atmosphere by land and ocean processes, and stored) of carbon dioxide.

Scientists have calculated that Nature cycles about 330 billion tonnes of carbon every year.

Human activities put about eight billion tonnes into the atmosphere - a tiny sum in comparison but enough, say researchers, to imbalance the system and raise the global mean surface temperature of Earth.

Of that eight billion, studies suggest about half remains in the atmosphere, says Dr Paul Palmer, a collaborator on the mission from the University of Edinburgh, UK.

"The remaining 50% gets taken up by the ocean biosphere and the land biosphere, or so we think. But if you take into account what we know about the oceans and the land, there is still a high percentage - something like 20% - which is poorly understood.

"We don't know where it goes, but we do know that this unaccounted sink changes in magnitude from year to year."

It could be going into land areas where trees, grasslands, crops and soil are absorbing carbon dioxide at a faster rate than previously been acknowledged.

These sinks are likely to include abandoned farmland where forests are re-growing.

They could also take in the northern, high-latitude forests that are experiencing longer, warmer growing seasons, allowing trees and shrubs to "bulk up" and absorb more carbon dioxide.

OCO measures carbon dioxide on the day-side of the Earth

"Even 'Smokey Bear' is a sink," said Professor Scott Denning, an OCO science team associate at Colorado State University, referring to the US Forest Service's anti-fire mascot.

"By putting fires out in our western forests and allowing the wood to accumulate, we are actually sequestering CO2."

To identify those currently poorly understood - or "missing" - sinks, OCO's data will have to be combined with models of how the air is transported through the atmosphere.

The famous US forest mascot may have a part in the story

Ultimately, researchers will use the OCO maps to assess how well the sinks are likely to perform over time.

"[Different climate] models show very different CO2 levels in the atmosphere for the same human emissions. So even though people are producing the same emissions in each of these models, the resulting CO2 in the atmosphere is very different by the end of the century due to the differences in land and ocean behaviour," explained Professor Denning.

"This actually shows up at about 300 parts per million (ppm) of difference in the amount of CO2 in the atmosphere - remember, we're at about 385ppm today. So this is a big difference and is really quite important for understanding future climate."

The OCO team is working closely with the Japanese Gosat ("Ibuki") mission which launched its carbon observatory last month.

The orbits of the two spacecraft will cross six times each day.

The groups use different measurement approaches, which will provide a cross-check on each other's data. Both will take their calibration from ground stations which, although limited in number, can measure CO2 with much higher precision at their locality.

Jonathan.Amos-INTERNET@bbc.co.uk

Rare cheetah captured on camera

Much more information is needed to better assess the animal's status

The first camera-trap photographs of the critically endangered Northwest African, or Saharan cheetah, have been obtained in an experiment in Algeria.

The images were captured as part of a project run by the Zoological Society of London (ZSL) and Office du Parc National de l'Ahaggar (OPNA).

The animal is known with certainty to range in six countries: Algeria, Togo, Niger, Mali, Benin, and Burkina Faso.

But the total population may be fewer than 250 mature individuals.

This is an incredibly rare and elusive subspecies of cheetah Farid Belbachir, Field surveyor

The pictures come from a systematic camera-trap survey across the central Sahara.

It managed to identify four different Saharan cheetahs using spot patterns unique to each animal.

"The Saharan cheetah is critically endangered, yet virtually nothing is known about the population, so this new evidence, and the ongoing research work, is hugely significant," said ZSL's Dr Sarah Durant.

Farid Belbachir, who is running the field survey, added: "This is an incredibly rare and elusive subspecies of cheetah and current population estimates, which stand at less than 250 mature individuals, are based on guesswork.

"This study is helping us to turn a corner in our understanding, providing us with information about population numbers, movement and ecology."

Populations are said to be very fragmented and small

A pride in peril

By Peter Bassett Producer, Nature's Great Events: The Great Migration

Advertisement

Lions suffer in Serengeti plains

The migration of wildebeest is one of the most familiar events on the globe.

Each year, over a million wildebeest and many hundreds of thousands of gazelles and zebras gather in one corner of Tanzania's Serengeti plains.

And for the predators here, with this plentiful food supply, it is a time to feast.

When the grazers are present, it is a time of feast for the lions

But what happens when the wildebeest and other grazers have gone?

Over the course of seven months, the BBC Nature's Great Events team followed a pride of lions, filming what happened to them in this land of constant change.

And the story was a harrowing one.

Everyone thinks of the lion as the "king of the beasts" - but when the wildebeest leave, these big cats do not follow.

They have a life system that is based on having home ranges and they hunt within this territory.

When they have thousands and thousands of wildebeest there, that is their time of paradise. But when the wildebeest leave, everything changes - this great larder of food just walks away.

Death's door

The year that we filmed was particularly hard for some of the lions - and for our cameraman Owen Newman, who has spent the past 20 years filming big cats in Africa, it soon became clear to him that the Ndutu pride, with its seven cubs, was struggling.

Lions keep to their own ranges

As the grazers left, the pride's four females struggled to find enough food and water, and over a period of just a few months, the number of cubs dwindled from seven to just four.

Even with all of his years of experience, Owen found this extremely difficult - he had never seen cubs so thin before, and the lions' plight began to affect him deeply.

And when two of the four cubs - a little female and its brother - became separated from their mother, calling out, emaciated and alone, Owen was sure that they were close to the end.

It seemed almost disrespectful to capture what could be their final hours on camera, so he finished filming as soon as he could and left them alone.

The next day, when he returned to the same spot, they had gone - and he assumed the cubs had died.

Unable to shift the scene from his mind, Owen kept on watching for the cubs - and to his surprise, one of them, the small female, who had seemed so close to death, managed somehow to rediscover the pride.

But just as this reunion provided a glimmer of hope for these desperate lions, the pride vanished and Owen was unable to find them before he had to return to the UK.

The Ndutu pride was filmed over several months

Months later, Owen returned to the Serengeti to resume filming.

The wet season had begun and the wildebeest were arriving and giving birth - but he could not shift the pride that had suffered such hardship from his thoughts.

He and his team were constantly on the look-out for them, using photographs of the lions' unique whisker patterns to see if any of the cats that had returned to feast on the wildebeest matched the animals he had filmed a few months before.

Finally, a local spotter reported a sighting.

And, when Owen reached the scene, he discovered that the pride had survived and the last two cubs were still alive - the little lioness that had rediscovered the pride and who had been so close to death's door just a few months earlier was now healthy and well fed.

For all of us, and especially Owen, it was an emotional and moving experience, and the little known story of what happens to the lions when the wildebeest are gone will surprise many people.

Nature's Great Events: The Great Migration is on Wednesday 25th February on BBC One at 2100 GMT and is repeated on Sunday at 1800 GMT

Google dismisses 'Atlantis find'

However closely you look, this is not the Lost City of Atlantis

The Lost City of Atlantis is still lost - despite hopes that Google Earth had located the fabled city on the floor of the Atlantic Ocean.

Observers noted what seemed to be a grid of streets and the outlines of a big city on the sea floor about 960km (600 miles) off the African coast.

Experts had said this was one of the possible sites of the city described by Plato, the Greek philosopher.

But Google said the lines represented sonar data collected from boats.

"It's true that many amazing discoveries have been made in Google Earth including a pristine forest in Mozambique that is home to previously unknown species and the remains of an Ancient Roman villa," a Google statement said.

The lines reflect the path of the boat as it gathers the data Google statement

"In this case, however, what users are seeing is an artefact of the data collection process. Bathymetric (or sea floor terrain) data is often collected from boats using sonar to take measurements of the sea floor," she added.

"The lines reflect the path of the boat as it gathers the data. The fact there are blank spots between each of these lines is a sign of how little we really know about the world's oceans."

The story of Atlantis, a fabled utopia destroyed in ancient times, has captured the imagination of scholars ever since it was first described by the philosopher Plato more than 2,000 years ago.

He wrote of a land of fabulous wealth, advanced civilisation and natural beauty. Debate rages over where it might lie, if it existed at all: some say it is near Cuba, off the coast of Cornwall, near Gibraltar or in the middle of the Atlantic.