Into the abyss: The diving suit that turns men into fish - Science, News - The Independent

Into the abyss: The diving suit that turns men into fish - Science, News - The Independent

By Jerome Taylor

Saturday, 20 November 2010

Humans have proven themselves remarkably adept at learning to do what other animals can do naturally. We have taught ourselves to fly like birds, climb like monkeys and burrow like moles. But the one animal that has always proven beyond our reach is the fish.

The invention of scuba diving has allowed us to breathe underwater but only at very shallow depths.

Thanks to our inability to conquer the bends, diving below 70m still remains astonishingly dangerous to anyone but a handful of experts. Ultra-deep diving is so lethal that more people have walked on the moon than descended below 240m using scuba gear.

Now an inventor in the United States believes he has solved the riddle of how to get humans down to serious depths – by getting us to breathe liquid like fish.

 

Arnold Lande, a retired American heart and lung surgeon, has patented a scuba suit that would allow a human to breathe “liquid air”, a special solution that has been highly enriched with oxygen molecules.

The idea immediately conjures up the terrifying spectre of drowning but our lungs are more than capable of taking oxygen from a solution.

“The first trick you would have to learn is overcoming the gag reflex,” explains Lande, a 79-year-old inventor from St Louis, Missouri. “But once that oxygenated liquid is inside your lungs it would feel just like breathing air.”

Lande envisages a scuba suit that would allow divers to inhale highly-oxygenated perfluorocarbons (PFCs) – a type of liquid that can dissolve enormous quantities of gas. The liquid would be contained in an enclosed helmet that would replace all the air in the lungs, nose and ear cavities.

The CO2 that would normally exit our body when we breathe out would be “scrubbed” from our blood by attaching a mechanical gill to the femoral vein in the leg.

By using oxygen suspended in liquid, divers would no longer have to worry about decompression sickness - the often fatal condition known as “the bends” which occurs when nitrogen dissolved in the blood under the immense pressures of deep water bubbles out as we rise. It could potentially allow them to descend to far greater depths than is currently possible.

Liquid ventilation might sound like science fiction – it played a major role in James Cameron’s 1989 sci-fi film The Abyss – but it is already used by a handful of cutting-edge American hospitals for highly premature babies.

Children born before 28 weeks have huge difficulties breathing, often because their lungs are not developed enough to comfortably adjust from the liquid environment of the womb to inhaling gaseous air. Immature alveoli, the final branchings inside the lung that feed oxygen into the blood, lack vital surfactants which stop the tiny cavities sticking together when we breathe out.

In response doctors have begun experimenting with highly-oxygenated PFCs with remarkable success.

Professor Thomas Shaffer, a paediatrics specialist from Delaware, has experimented with liquid breathing since the late 1970s. He spent much of his early career testing various animals in oxygenated PFCs.

Place a mouse in oxygenated liquid and instinct immediately kicks in as the animal flounders wildly. Everything the mouse has ever learned screams at it to avoid inhaling a solution it thinks will kill it.

Yet when we drown there comes a moment when the instinct not to breathe liquid is overridden by a stronger instinct to take in one last breath. It is a desperate final attempt to get oxygen into the blood. If the liquid we are in contains oxygen molecules that happily cross from the solution into our blood stream, life will return. After all, it is not water that kills us when we drown. It’s our inability to take oxygen from the water that condemns us.

By the mid-1990s, Shaffer and a handful of doctors had begun using liquid ventilation techniques on premature babies and were stunned by the results.

“A lot of the children I see have less than a 5% survival rate,” he explains. “But when we get them on to liquid breathing we see close to 60% going on to lead fully healthy lives.”

The technique remains rare, however, because of a chronic lack of investment.

“Liquid ventilation is not used widely because there is very little funding from the drug companies,” he says. “Unfortunately premature babies don’t have a voice. They don’t bring in money, so no-one really wants to invest. But it does work. Physiologically, liquid ventilation is very do-able.”

The recent oil spill in the Gulf may change that lack of interest. Although drug companies are reluctant to fully explore liquid breathing, the Deep Water Horizon disaster has reignited the debate over how to get divers safely down to extreme depths.

Currently the only way divers can work for long spells in the deep is either from the safety of robotic vessels and submarines; or by using saturation diving, an incredibly complicated technique where divers have to be brought up to the surface in a pressurised container over a matter of weeks.

With saturation diving, the deepest anyone has gone is 701m. Using scuba equipment the record is 318m, set by the South African diver Nuno Gomes in June 2005. It took him 14 minutes to descend and 12 hours to come back up to the surface.

The reason for these slow ascents is our reliance on compressed gasses to breathe in water. Under the incredible pressure exerted by billions of tonnes of ocean, gasses like nitrogen and helium dissolve into our bloodstream, much like CO2 is dissolved in a soda bottle.

Ascending towards the surface is like opening that soda bottle - the gas comes out of solution and into our bodies. If we don’t give our bodies enough time to expel those gasses by ascending slowly, we die.

“The beauty of doing it all from a liquid is that you don’t have to use these highly compressed gasses in the lungs that are going to dissolve into the blood,” says Dr Lande, who recently presented a paper on his patent to the first International Conference on Applied Bionics and Biomechanics in Venice. “You have a liquid that you can infuse just as much oxygen as you need.”

Shaffer has previously experimented with animals and PFCs at depth and found the technique to work. “I have personally put mammals down to a simulated depth of 1000 feet and then decompressed them in half a second and they have no decompression sickness,” he says.

The US Navy Seals also reportedly experimented with liquid ventilation in the early 1980s according to Shaffer who says he met a former Seal turned doctor that was on the team.

“This paediatrician never really revealed why they were doing it,” he explains. “Other than going very deep I don’t know what the point was. But they tried it. The Navy pushed them to the point where they did it several times a week.”

Being so much more viscous than air, liquid is difficult to breathe. Some of the Seals reportedly developed stress fractures on the ribs cause by the sheer force of trying to get a liquid in and out of the lungs.

But Lande envisages using a cuirass, a ventilation device named after a piece of medieval armour, which compresses the diaphragm and makes it easier to breathe liquid.

Now all he needs now are developers and a fresh set of human guinea pigs willing to test his ideas.

“I’m sure someone out there would be willing,” he says. “We’ve climbed the highest mountains, sent people into space. It’s time to find ways of exploring the deep oceans

Massive Count a Drop in the Bucket - US News and World Report

Massive Count a Drop in the Bucket - US News and World Report

By Susan Milius, Science News
A 10-year international project called the Census of Marine Life has come to an end with what has to be one of the strangest census reports ever.
At the project’s finale in London October 4, a summary of the collaboration by 2,700 scientists from more than 600 institutions around the world highlighted their own undercounts and the vast realms they missed. That, however, was the point.

“There’s a lot of ocean left to explore,” says environmental scientist Jesse Ausubel, a census cofounder and program officer of the Alfred P. Sloan Foundation. The water world covers the majority of the planet, feeds people far inland, offers exotic compounds for drugs and manufacturing, regulates the planet’s climate and provides half its oxygen, but has yet to be fully explored.
How many fish in the sea? The census didn’t try to count, since scientists haven’t even finished naming species of marine fish. According to the census summary, the tally of 16,764 marine fish species formally named as of early 2010 probably falls short by an estimated 5,000 species.
And fish aren’t the half of it. They’re perhaps 12 percent of the total of marine species, according to the census estimates. Fishes trail after crustaceans and mollusks in number of species, and researchers report evidence of major undercounts in the numbers of recorded species for these other groups too.
Overall at least 750,000 marine species, not including microbes, still await discovery, the census teams predict. In the seas, the mysteries easily outnumber known species, now estimated at 250,000.
For microbes, the census researchers report boggling diversity. Analyzing a liter of seawater revealed 38,000 kinds of microbes, and census DNA sequencing has turned up specimens of more than 100 phyla. Such breadth approaches three times the number of phyla known in the animal kingdom. Estimates for the total number of kinds of marine microbes run as high as a billion.
Undersampling afflicts oceans everywhere to some degree, the researchers conclude. Perhaps 80 percent of the nonmicrobial species around Australia have not been described. Even in the Mediterranean, 75 percent of deep-sea species do not yet have names.
Deep waters below 200 meters are so underexplored that their life forms constitute “biodiversity’s big wet secret,” says the census’s chief scientist, Ron O’Dor of Dalhousie University in Halifax, Canada. Fewer than 10 percent of records of marine life come from the zone of abyssal plains between 4,000 and 5,000 meters deep, yet that zone accounts for half the oceans’ area.
To count fish, or even guesstimate abundance of the small proportion of known marine species, “you need a spread sheet,” Ausubel says. “And you didn’t have one.” So a major goal of the census has been to organize records of marine life.
The Ocean Biogeographic Information System database now allows anyone to look up what species have been found where. More than 90,000 of the species also have their own Web page in the Encyclopedia of Life.
Even though census scientists highlight how much is left to discover, they did a lot of exploring in 10 years. Out of the 17 teams that make up the census, 14 emphasized field expeditions, logging more than 9,000 days at sea sampling such places as seamounts or the Mid-Atlantic Ridge. More than 6,000 potential new species turned up, with 20 percent already confirmed.
These new explorations made a particularly big difference to the knowledge of life at the poles, which aren’t easy or cheap places to study, Ausubel says. Sending a ship exploring in Antarctica costs about $125,000 a day.
Among all the discoveries from the field, “what surprised me is the beauty,” Ausubel says. Census projects encouraged photography, and the stream of pictures over the years has introduced a wide public to the charms of deepwater crabs or free-swimming sea cucumbers.
Census workers also looked into the dark side of ocean studies, assessing how human activities such as fishing have changed marine populations. Delving into documents from monasteries or old tax records, researchers pieced together trends. Effects show up as far back as Roman times, researchers found. O’Dor, however, points out that the census also documents recoveries from human impact. “Under the right circumstances, the ocean is resilient,” he says.
These themes of a great undiscovered diversity of organisms at risk from human activity aren’t unique to the sea, says Peter Raven, president emeritus of the Missouri Botanical Garden in St. Louis. “The Census of Marine Life certainly ought to be replicated on land, where the vast majority of species are unknown and for even those we know, we have very little information available,” he says. “This is basically an unknown planet when it comes to living organisms.”

Solving Engineering Issues by Studying Jellyfish - US News and World Report

Solving Engineering Issues by Studying Jellyfish - US News and World Report

By Marlene Cimons, National Science Foundation
Jellyfish create doughnut-shaped currents of rotating water when they swim. Visually, they resemble what happens when someone blows smoke rings from a cigar.

More importantly, however, this unusual method of propulsion, these so-called “vortex rings,” enable jellyfish to go further on less energy, an idea that scientists hope to translate into new engineering designs.
“We’re very interested in figuring out things that animals do better than we, as engineers, can do,” said John Dabiri, professor of aeronautics and bioengineering at California Institute of Technology, who is heading the project. “We’d like to co-opt some of those ideas.”
In particular, they want to build new underwater research vehicles that can remain beneath the ocean surface for years at a time, rather than only hours or months, and on less fuel.
“It is important to have underwater vehicles that can study the changing properties of the ocean, such as temperature and pH, so we can improve our knowledge of the ocean and how it works,” said Dabiri, who recently was among those named to receive a prestigious $500,000 MacArthur “genius’’ award, a “no-strings attached’’ fellowship. “This is especially important in trying to understand the impact of climate change on the ocean.”
Jellyfish propel themselves by contracting cells in their bell-shaped outer skin and generating jet forces in the tail end, with tentacles trailing behind. “Pretty much all underwater swimmers create these vortex structures, but theirs are a lot more complicated [than jellyfish] in flow currents,” Dabiri said. “Their rings are jumbled together in ways more difficult to measure.”
Beyond inspiring new energy-saving underwater technology, understanding the fluid dynamics of the jellyfish also ultimately could provide important information applicable to other related areas, such as blood flow in the human heart or the design of wind power generators.
The National Science Foundation is supporting the research with $170,000 as part of the American Recovery and Reinvestment Act of 2009.
“In the short term, we’re using this money to buy equipment for the labs to build the experiments we take out into the water, which is supporting the small businesses that are building these devices for us,” Dabiri said. “In the long term, the most important investment is in energy efficiency. By making underwater vehicles that are less reliant on huge amounts of fuel, the fuel that is saved either can go to other uses or stay in the ground.”
Dabiri, a biophysicist whose research encompasses several fields, including theoretical fluid dynamics, evolutionary biology and biomechanics, has shown that explaining the workings of locomotion depends on a mathematical analysis of the fluid vortex rings that jellyfish form in the surrounding water by contracting their bells. His research team, in ocean experiments, “scuba dive up close to the jellyfish,” to video them and take certain measurements.
To get a rough idea of what the animals are doing, the researchers add dye to the water. Then, in order to gather more quantitative data, they illuminate the water with a laser, allowing the scientists to see the sediment generated in the water by the jellyfish movement. “We can track the motion of those particles over time to infer the water velocity,” a process known as digital particle image velocimetry, he said.
“We’ve already demonstrated reductions in energy use by 30 percent compared to conventional propeller-driven submarines,” Dabiri said.
Today’s ocean explorer vehicles can spend only short periods of time underwater, or, in the case of gliders, must change their locations frequently. Most other sea research is conducted primarily with satellite technology. The latter “gives coverage of the ocean surface, but doesn’t tell you what’s happening beneath the surface,” he said.

Ocean gliders can remain underwater for months, but must constantly change their depth in order to function.  “It’s difficult to get one of them to stay at the same depth for an extended period of time,” Dabiri said. “We’d like to develop vehicles that can remain at a fixed depth for longer periods of time.”
He described what he considers the perfect arsenal of underwater vehicles, and the challenges involved, that would be necessary to draft a comprehensive map of ocean properties, satisfying current research goals.
“The fundamental issue is space,” he said.  “Since these would be smaller, we can only fit so many batteries and so much fuel on board. If we can make them go farther and faster on the same amount of fuel, that would allow them to go for a long duration of time.
“We need tens of thousands of these underwater vehicles to get the proper coverage of the ocean,” he added.  “We need them not for hours at a time but for years. They would be autonomous. They would have their own sensors that would navigate. We would give the vehicle a set of instructions, put it in the water and have it go on its way.”

Oceanographers With Flippers - US News and World Report

Oceanographers With Flippers - US News and World Report

By Alexandra Witze, Science News
Seals diving for their dinner near Antarctica have surfaced with an extra morsel: information, gathered by electronic tags on the animals’ heads, about the shape of the seafloor there.

The work has revealed previously unknown undersea channels, through which warm water might flow toward fragile ice shelves. And the seals do it all for a fraction of the cost of traditional seafloor mapping done from ships.
“It gives you a much denser picture of what the water depth is than anything you can conceivably do with ship tracks,” says Laurence Padman, an oceanographer at Earth & Space Research in Corvallis, Ore., and a coauthor of an upcoming paper in Geophysical Research Letters describing the technique.
Seals, walruses, whales and other large marine creatures have moonlighted as oceanographers before. Scientists typically glue sensors to the animals’ bodies that measures factors like temperature and salinity. Researchers have used this information to study water temperatures around Greenland, among other topics.
But the new work is the first to extract information on the shape of the seafloor—known as bathymetry—from the sensors, which also measure pressure and hence depth. “You can actually map the ocean floor,” says team member Daniel Costa, a marine biologist at the University of California, Santa Cruz.
The data came from 57 elephant seals, tagged by Costa’s group over five summers at the U.S. Antarctic Marine Living Resources camp in the South Shetland Islands. As the animals swim, the tags record information every few seconds, then relay it via satellite once the seals surface. About 30 percent of the time seals dive all the way to the bottom to forage for food, says Padman, so by studying enough dives for each animal—some 200,000 dives in total—the researchers can deduce where the seafloor lies.
“It’s a novel and useful technique for gathering bathymetry data,” comments Paul Holland, an ocean modeler at the British Antarctic Survey in Cambridge, England.
Within the seal data Padman’s team discovered several significant troughs cutting across the continental slope off the west side of the Antarctic Peninsula. These features hadn’t been mapped before, says Padman, yet they play an important role in ocean circulation. Warm water can flow through such channels and up under the floating ice shelves that extend off Antarctica, such as the Wilkins ice shelf that partially disintegrated in 2008.
Better information on underwater topography could lead to improved models of how the ocean will respond to climate change, says Padman.
Other researchers might now be inspired to dig through seal data to see what features could be mapped, he adds. Ships can cost tens of thousands of dollars a day to operate in Antarctic waters, whereas there is a wealth of readily available information available on seal tags.
“We want to encourage other people who work with seal data to look into it,” says Padman. “We just thought it was really cool.”

Derbies helping eliminate invasive lionfish - ESPN

Derbies helping eliminate invasive lionfish - ESPN

KEY WEST, Fla. -- There are 659 less Indo-Pacific red lionfish occupying the waters of the Florida Keys National Marine Sanctuary.

Courtesy Fla-Keys.comA diver is careful while gathering one of the venomous lionfish.

The final in a series of three lionfish derbies was staged Saturday, Nov. 13, off the Lower Keys and divers captured 109 of the invasive species, adding to the totals of two previous contests staged in Key Largo in September and in Marathon in October.

During Saturday's derby, Melbourne, Fla., residents Rob Pillus, Jeremy Norcross and Mike Dugan caught 25 lionfish to capture the contest's top $1,000 prize.
Lionfish off the southeast U.S., Bahamas and in the Caribbean impact indigenous fish because they eat important juvenile reef species, such as grouper and snapper.
Lionfish have no known predators except man, said Lad Akins of the Reef Environmental Education Foundation.
They have venomous spines but, when properly cleaned, yield a white meat that is considered a delicacy. Saturday night's derby banquet featured lionfish.
Organized efforts to control the lionfish population and educate divers on the benefits of killing lionfish are to continue Dec. 8 with another derby that coincides with celebration activities surrounding the 50th anniversary of the establishment of John Pennekamp Coral Reef State Park in Key Largo. The park is America's first underwater preserve.
Learn more and sign up at Pennekamp Lionfish Roundup.

Gulf corals adapt to warmer water, still in peril | Reuters

Gulf corals adapt to warmer water, still in peril Reuters

(Reuters) - Twenty years ago, divers in Dubai could swim through coral gardens teeming with brightly-colored fish and sea turtles. Today, says marine biologist Tom Goreau, dead reefs stand like gravestones for an underwater ghost town.
In the United Arab Emirates, some of the world's glitziest building projects, such as the opulent homes on one of Dubai's manmade palm-shaped islands, sit on these coral cemeteries.
"The best reefs were simply dumped on," said Goreau, who heads the U.S.-based Global Coral Reef Alliance. "Those areas that were supposed to have been protected areas were peddled off to developers. They're gone, wiped out."
Surviving reefs contend with desalination plants, necessary for supplying fresh water to the desert countries along the Gulf coast. The plants spew hot brine and chemicals into the sea, warming their surrounding waters and increasing salinity.
Twenty percent of the world's reefs are damaged beyond repair. Scientists are uncertain about what proportion of the Gulf's reefs have died. A Kuwaiti diving team recently reported that 90 percent of the coral off Kuwait's coast was dead or severely stressed. Qatar has also seen dramatic coral death.
Scientists worry pollution and construction continues at a rate that could kill Gulf reefs, which had proven resistant to rising temperatures and increased ocean salinity.
Coral reefs support a third of the Gulf's fish populations -- and local economies.
"We don't protect corals just because they're beautiful," said Rita Bento, marine biologist for the Emirates Diving Association. "Corals are a source of food, fishermen go there to fish. Tourism also -- places with good reefs that are protected have economic growth. We have a lot to gain from them."
The UAE is growing more aware of climate threats, adding government environment advisers to approve coastal construction plans. Abu Dhabi is sponsoring the development of what it calls the first zero-emissions city, Masdar.
Overfishing is another problem, but scientists say damage to reefs, where fish feed and breed, may also be behind what Dubai fishermen say is a 20 percent drop in their catch since 1990.
"It's not like it was years back. There were a lot of fish and it was so cheap," said one fisherman, dumping baskets of brightly striped fish off his tiny motor boat for market.
RED TIDE
Hamad al-Roomy, general manager of the Dubai Fishermen's Cooperative, says in 2008 Gulf waters were invaded by a red tide, or harmful algae bloom, often caused by a sudden temperature change.
"It hit like a nuclear bomb that kills everything around it," he said. "You could see the red tide coming. The fish were trying to escape. They'd just jump right onto the beach."
Red tides soak up oxygen, suffocating fish. Hundreds of thousands of fish were killed in a single day. Months later, residual algae killed swathes of coral on the UAE's east coast.

Some scientists think red tides could become more common due to the warming of Gulf seawater, which is occurring faster than anywhere else in the world, probably accelerated by pollution. Gulf Arab states have some of the world's highest per capita carbon emissions. World Bank and other data from 2006 and 2007 shows Qatar topping the table. Pollutants can take years to be flushed out of the Gulf, which is almost entirely sealed from the wider ocean except at the narrow Strait of Hormuz, through which passes 40 percent of the world's seaborne oil. SOURCE OF HOPE But scientists say it is not the amount of coral death in the Gulf that surprises them, it's how much has survived. Most corals cannot live in temperatures above 28 degrees Celsius (82 Fahrenheit), says Thabit Abdelsalaam, of the Abu Dhabi government's Environmental Agency. "Our corals live and survive at 37 degrees centigrade," he said. "That could be a source of hope around the world." The Gulf differs from most other seas where coral is found because at only 20,000 years old it is an evolutionary newcomer. "Corals haven't had time to adapt into new species... but here, they've already adapted to high temperatures," says Keith Wilson of the Emirates Marine Environmental Group. Researchers see a chance to learn how these corals adapted and to determine if this could be repeated elsewhere. "This is an area where we can travel to the future and see how climate change will affect things," Bento said. "I wish I had more answers for you, but we don't have enough research." Curbing pollution will not come easy in Gulf countries like the UAE, where oil money has built glittering villas and skyscrapers to replace the modest palm-frond homes of earlier generations. Growth in the Gulf means more desalination. The UAE alone produces 9 million cubic meters of water daily and is planning to build six more plants to add another 4 million cubic meters. "We can't stop development," said Abdelsalaam. "But we can make sure there's a balance between development and preservation of the environment." Graduate student Richard Wagner carried out a study on how UAE residents view the threat to coral reefs. Most do not care. "I told them that if the reefs die, most of their fish would die. They would say: 'we can just import more'." (Editing by Alistair Lyon and Janet Lawrence)

How Diving Leatherback Turtles Regulate Buoyancy - US News and World Report

How Diving Leatherback Turtles Regulate Buoyancy - US News and World Report

Leatherback turtles are remarkably versatile divers. Routinely diving to depths of several hundred meters, leatherbacks are occasionally known to plunge as deep as 1250m. The animals probably plumb the depths to avoid predators, search for prey and avoid heat in the tropics. However it wasn't clear how these mammoth reptiles regulate their buoyancy as they plunge down. Sabrina Fossette from Swansea University explains that no one knew how the turtles descended so far: do they swim down or become negatively buoyant and plummet like a stone? Curious to find out how nesting leatherbacks plumb the depths, Rory Wilson and his long time collaborator, Molly Lutcavage, decided to deploy data loggers containing triaxial accelerometers on leatherback females as they nested on beaches on St Croix in the US Virgin Islands. They found that leatherbacks probably regulate their buoyancy by varying the amount of air they inhale just before submersion and publish their discovery on Nov. 12, 2010 in the Journal of Experimental Biology at http://jeb.biologists.org/cgi/content/abstract/213/23/4074.

'When you first see a leatherback turtle coming out of the water it's like a dinosaur it's really impressive,' says Fossette, having just returned from collecting data in the Indian Ocean. According to Fossette, Andy Myers, Nikolai Liebsch and Steve Garner attached accelerometers to five females as they laid their eggs, and then waited 8-12 days for the reptiles to return to the beach to lay more eggs having headed out to sea. Retrieving the accelerometers, the team found that only two of the five had collected usable data, but the data loggers that functioned showed 81 dives that the team could analyse ranging from 64m down to 462m.
Back in Swansea, Fossette, Adrian Gleiss, Graeme Hays and Rory Wilson analysed the temperature, pressure and acceleration data collected by the loggers. Describing the accelerometer data Fossette says, "You can almost see the animal swimming. It's the first time we could see the locomotor activity during those deep dives."
Extracting the acceleration data that showed the leatherbacks' movements, the team could see that the turtles dived deeply at an average angle of 41deg as they began their descent. Initially the turtles swam with each flipper stroke lasting 3s, but as they descended further they swam less hard until they stopped swimming all together, became negatively buoyant and began gliding down. At the bottom of the dive, the turtles began swimming as they heading to the surface and continued swimming until they regained buoyancy near the surface and began gliding again.
Fossette explains that many diving animals exhale before they leave the surface to minimise the risk of decompression sickness, however, leatherbacks do not. They dive carrying a lung full of air. Curious to find whether leatherbacks vary the amount of air that they inhale to regulate their buoyancy, Fossette and Gleiss compared the depths at which the turtles became negatively buoyant with the maximum depth that they reached. The team found that the deepest divers remained buoyant the longest and started gliding at deeper depths. So the turtles probably regulate their buoyancy before diving by varying the amount of air they inhale. Fossette also says, "The nesting turtles may glide for 80 percent of the dive's descent to optimise their energetic reserves, which is crucial for the production of eggs."
The team is now keen to look at the diving patterns of leatherbacks in their foraging grounds in the North Atlantic. Fossette explains that nesting turtles lose weight while foraging turtles are gaining weight and this could affect their buoyancy and diving behaviour. However, tagging a 400kg turtle in the ocean is a much bigger problem than tagging them on a beach.