Sonar Noise Behind Whale Deaths

The deaths of over 100 melon-headed whales, which stranded on the shores of a lagoon in northwest Madagascar in 2008, were likely primarily triggered by a form of sonar being deployed by an ExxonMobil survey vessel, according to a scientific review panel.

This is the first known marine mammal mass stranding event to be closely associated with what are known as high-frequency mapping sonar systems; but it is merely the latest in a long line of incidents in which industrial noise in the ocean has been implicated in deaths and injuries to marine mammals, and specifically cetaceans.

One area of particular focus is the use of active sonar by the United States and other navies. In 2004, the Scientific Committee of the International Whaling Commission concluded that “there is now compelling evidence implicating military sonar has a direct impact on beaked whales.” In 2001, the U.S. Navy acknowledged that its active sonar played a role in the stranding deaths of 14 beaked whales, two minke whales, and a dolphin in the Bahamas in 2000. Necropsies of the beaked whales revealed that the animals had suffered acoustic trauma resulting in hemorrhaging around the brain, in the inner ears, and in the acoustic fats located in the head that are involved in sound transmission.

Then there is the use of air guns to conduct seismic surveys for oil and gas deposits in the sea bed. Because of concerns that the intense sounds from these air guns can either cause physical damage to cetaceans or cause them to flee, the U.S. Marine Mammal Protection Act requires visual observers to examine the area for marine mammals for a period of at least 30 minutes. Assuming the coast is clear, the survey must ramp up slowly by firing first one seismic gun and then others over a period of between 20 and 40 minutes. However, if a whale or other marine mammal appears within an exclusion zone of 500 meters from the center of the seismic array, the operation must shut down, and visual examination must resume for 30 minutes.

The presence of seismic survey vessels was initially considered a likely reason for the 2008 Madagascar incident, not least because melon-headed whales are an open-ocean species that had never before (and have never since) been recorded in the island’s shallow tidal Loza Lagoon estuarine system; it seemed reasonable to infer that something had startled them into entering the area. Experts with the International Fund for Animal Welfare and the Wildlife Conservation Society attempted to rescue the whales, but with minimal success, largely because of the large distance (over 69 km/43 miles) from the point where they were becoming stranded to the open ocean.

Following the incident, the International Whaling Commission facilitated a review of the evidence and an Independent Scientific Review Panel (ISRP) of five experts was invited to examine that evidence. The ISRP has just published its findings, and concluded that air gun blasts from seismic survey vessels in the area were not to blame, as they in fact took place several days after the incident.

However, a vessel using a different type of surveying technique — a high-power 12 kHz, multi-beam echosounder system (MBES) — was, says the report, “moving in a directed manner down the shelf-break the day before the event, to an area  approx. 65 km offshore from the first known stranding location. The ISRP deemed this MBES use to be the most plausible and likely behavioral trigger for the animals initially entering the lagoon system.”

Most attention has focused on the likely impacts of mid-frequency and low-frequency sound sources, because of their greater propagation through water; it is possible, the ISRP noted, that high-frequency sounds like the MBES also affect some cetaceans more than previously realized but that, under normal circumstances, those cetaceans swim away. It was to the considerable misfortune of those melon-headed whales five years ago that they were in the wrong place at the wrong time, and that when they turned tail and fled, they swam into an inhospitable area from which there was no escape.

Read more at Discovery News

SUNRISE Offers New Insight On Sun's Atmosphere

Three months after the flight of the solar observatory Sunrise -- carried aloft by a NASA scientific balloon in early June 2013 -- scientists from the Max Planck Institute for Solar System Research in Germany have presented unique insights into a layer on the sun called the chromosphere. Sunrise provided the highest-resolution images to date in ultraviolet light of this thin corrugated layer, which lies between the sun's visible surface and the sun's outer atmosphere, the corona.

With its one-meter mirror, Sunrise is the largest solar telescope to fly above the atmosphere. The telescope weighed in at almost 7,000 pounds and flew some 20 miles up in the air. Sunrise was launched from Kiruna in the north of Sweden and, after five days drifting over the Atlantic, it landed on the remote Boothia Peninsula in northern Canada, gathering information about the chromosphere throughout its journey.

The temperature in the chromosphere rises from 6,000 K/10,340 F/5,272 C at the surface of the sun to about 20,000 K/ 35,540 F/19,730 C. It's an area that's constantly in motion, with different temperatures of hot material mixed over a range of heights, stretching from the sun's surface to many thousands of miles up. The temperatures continue to rise further into the corona and no one knows exactly what powers any of that heating.

"In order to solve this riddle it is necessary to take as close a look as possible at the chromosphere -- in all accessible wavelengths," said Sami Solanki, the principal investigator for Sunrise from the Max Planck Institute. Sunrise used an instrument that was able to filter particular ultraviolet wavelengths of light that are only emitted from the chromosphere.

Sunrise's extremely high-resolution images in this wavelength painted a complex picture of the chromosphere. Where the sun is quiet and inactive, dark regions with a diameter of around 600 miles can be discerned surrounded by bright rims. This pattern is created by the enormous flows of solar material rising up from within the sun, cooling off and sinking down again. Especially eye-catching are bright points that flash up occasionally -- much richer in contrast in these ultraviolet images than have been seen before. Scientists believe these bright points to be signs of what's called magnetic flux tubes, which are the building blocks of the sun's magnetic field. The magnetic field is of particular interest to scientists since it is ultimately responsible for all of the dynamic activity we see on our closest star.

Read more at Science Daily

Goosefish Lays Veil Holding 1 Million Eggs

Goosefish, also known as monkfish, may be among the most aesthetically challenged creatures around, but when the homely bottom-feeders lay their eggs, they create something beautiful: a gauzy, billowy veil that drifts in the ocean for days.

On Monday afternoon (Sept. 23), a female monkfish at the New England Aquarium in Boston laid her third egg veil this year.

The veil looks something like a 60-foot-long (18 meters) sheet of delicate bubble wrap, covered in about a million pinhead-sized eggs waiting to be fertilized.

"In the wild, when the female is swimming around releasing the egg veil, the male is swimming around her and as they intertwine, the male releases its sperm," aquarist Bill Murphy, of New England Aquarium, told LiveScience.

The aquarium's female fish doesn't have a male counterpart, so these eggs won't result in any offspring. (Murphy said he tried putting two of the fish in one tank before, but they are a solitary, predatory species, and the pairing didn't work out.) For now, visitors will be able to see veil float around in the goosefish's tank until it starts to rot.

Murphy said he didn't catch the veil-laying on Monday, but in the weeks leading up to the moments-long event, there are usually signs that a sheet of eggs is coming — namely, the fish starts looking bloated.

"She looks huge, like she swallowed a beach ball," Murphy said.

Monkfish are anglerfish that sit, partially buried, at the bottom of the ocean, attracting prey with a lure in the form of a flap of skin that looks like a small fish, Murphy said. When its victim is close enough, the monkfish opens its big mouth suddenly, creating a vacuum to suck in its prey.

Read more at Discovery News

To Avoid Fights, Mice Sing to the Clouds

Deep in the cloud forests of Central America, two species of singing mice put on a high-pitched opera to mark their territory and stave off clashes, researchers discovered.

Alston's singing mouse (Scotinomys teguina) and the Chiriqui singing mouse (S. xerampelinus) have overlapping lifestyles in the cloud forests of Costa Rica and Panama. But the tawny cousins seem to establish geographic boundaries so they can avoid competing with each other.

"A long-standing question in biology is why some animals are found in particular places and not others," study researcher Bret Pasch, a postdoctoral fellow at the the University of Texas at Austin, said in a statement. "What factors govern the distribution of species across space?"

As it turns out, a little communication between individuals affects the spread of both species as a whole.

Both species of singing mice produce vocalizations that are barely audible to humans. As video footage of the mouse-y opera from the foggy forest floor shows, the creatures throw their heads back and belt out songs in the form of rapidly repeated notes, known as trills. The Alston's mouse in the clip even looks likes it's taking a bow after its solo. (Watch Video of Singing Mouse)

Researchers already knew that the rodents sing to attract mates and repel rivals within their own species. But Pasch and colleagues found that these high-pitched tunes can serve as signals across species, too, helping males protect their turf.

Through experiments in the field and in the lab, the researchers noticed that the larger Chiriqui mice are less tolerant of heat. The creatures are typically spread throughout the cooler, higher-altitude parts of the cloud forests, and dominant Chiriqui males sing in response to potential intruders of both species, the researchers found.

Meanwhile, Alston's mice are more flexible when it comes to temperature; they will spread into cooler, higher habitats if no Chiriqui mice are around to push them out. But when an Alston's male hears the song of its larger cousin, it will stop its own singing and flee to avoid confrontation, the researchers found.

Read more at Discovery News

Global Warming: Why Only 95 Percent Certainty?

Climate scientists meeting Friday in Stockholm declared that there’s a 95 percent likelihood that climate change is the result of human activity, primarily the burning of fossil fuels which release carbon dioxide and other heat-trapping gases into the atmosphere.

But why isn’t that figure 99, or even 100 percent?

It turns out that the massive report by the Intergovernmental Panel on Climate Change can say some things with absolutely certainty, or 100 percent probability. That includes findings that the planet is warming, the seas are rising and glaciers in Antarctica, Greenland and other mountain regions are melting. It also includes the fact that human activity is pushing up levels of atmospheric carbon dioxide that are the highest in 800,000 years.

But when it comes to the links between human activity and the climate, scientists have to rule out all other kinds of natural variability, according to Christopher Field, a climate scientist at the Carnegie Institution for Science who worked on the IPCC report.

“It’s a 95 percent probability that more than half of the climate change is from human actions,” Field said. “The 95 percent leaves only a sliver of doubt. In most of science when we say were convinced, we say less than 1 in 20 chance. So that’s one of the reasons the 95 percent standard is appropriate here.”

The 5th IPCC report has a higher confidence that the 4th report, which stated the same cause and effect at 90 percent. That’s because measurements of the Earth’s climate are more accurate, more widespread and cumulatively larger than the last report, Field said.

Still, the Earth’s atmosphere is not a test tube. There are other factors that come into play, such as the natural variability of the climate over time, as well as effects of volcanic gasses.

In fact, the 95 percent figure cited in the summary of the four-part IPCC assessment applies to the overall report, not individual statements on the human impacts of climate change, according to Shang-Ping Xie, another report author and climatologist at the Scripps Institution of Oceanography in La Jolla, Calif.

Read more at Discovery News

The Dead Spinning Star With a Split Personality

Within a cluster of stars 18,000 light-years away, near the bustling center of the galaxy, a pair of stars is locked in a tight and dramatic orbital embrace. One is a puffy low-mass star; the other a rapidly-spinning neutron star, a super-dense stellar corpse that pulls in material from its companion. Together this binary pair creates a bright x-ray source known as IGR J18245-2452 — and it exhibits not just one but two very different personalities.

As material from the large, low-mass star is pulled into a hot accretion disk swirling around its companion and interacts with its magnetic field, powerful x-rays are emitted, detectable as a “low-mass binary” by x-ray-sensitive telescopes like NASA’s Chandra X-ray Observatory and ESA’s XMM-Newton.

But as the neutron star absorbs material from the spinning accretion disk it gains momentum, spinning faster and faster and ramping-up its magnetic field even further. As the flow of material from the low-mass star slows, the neutron star — now spinning madly, up to 254 times a second — throws much of the material in the disk out of the system entirely. With the x-ray emitting material gone, the neutron star is free to blast jets of radio waves out into space from its poles. It’s now a millisecond pulsar, and to anything aligned with its poles it flashes in radio like a lighthouse beacon on overdrive.

Talk about dancing with the stars.

While the full transition of a low-mass x-ray binary to millisecond pulsar is a process that’s thought to take place over billions of years, IGR J18245-2452 has given astronomers evidence that switches — in both directions — can occur much more rapidly… within a period of just a few days, in fact.

It’s the first time that the transition between these particular two stages of stellar evolution has been directly observed.

“We’ve been fortunate enough to see all stages of this process, with a range of ground and space telescopes. We’ve been looking for such evidence for more than a decade,” said Dr. Alessandro Papitto, lead author of the paper published in the Sept. 26, 2013 issue of Nature.

“It’s like a teenager who switches between acting like a child and acting like an adult,” said John Sarkissian, a co-author who observed the system with CSIRO’s Parkes radio telescope in Australia.

Read more at Discovery News

'Tidal Body Clocks' Found in 2 Marine Animals

Most animals have a circadian clock that helps them distinguish night and day, but now researchers have found coastal animals seem to be equipped with a separate clock to track time via the tides.

The evidence comes from the discovery of internal clock genes that help some marine animals track the ebb and flow of the tides, according to two studies detailed today (Sept. 26) in the journals Current Biology and Cell Reports.

"The discovery of the circadian clock mechanisms in various terrestrial species from fungi to humans was a major breakthrough for biology," said Current Biology study co-author Charalambos Kyriacou of the University of Leicester, in a statement. "The identification of the tidal clock as a largely separate mechanism now presents us with an exciting new perspective on how coastal organisms define biological time."

Though the tidal clocks have only been found in two species so far, it's possible that multiple internal clocks could be widespread in sea-dwelling -- and perhaps land-dwelling -- creatures.

Internal clocks

For years, scientists thought the circadian clock guided the tidal behavior of marine animals. In almost all land-based animals, including humans, the circadian clock orchestrates rhythmic changes in physiology and behavior based on night and day.

But for animals at sea, life is guided by the ebb and flow of the tides, caused by the moon's gravitational pull on the Earth. For instance, a crustacean called Eurydice pulchra swims out in search of food with the incoming tides, then burrows in the sand once the tide departs.

To understand how animals keep track of this ocean rhythm, Kyriacou and his colleagues caught Eurydice pulchra off the coast of Wales every season, then identified their circadian clock genes. When they turned off those genes or disrupted the circadian cycle by exposing the creatures to bright light for several days, they found that cells linked to natural sunscreens were completely thrown off.

Yet like clockwork, the crustaceans still swam out every day on 12.4 hour cycles, suggesting the creatures had a separate internal clock anchored by the tides.

"This shows that the 12.4 hour clock is independent from the circadian clock. I expect tidal rhythms in many coastal organisms will follow this rule, including insects, crabs, even plants," Kyriacou said.

Multiple species

In another study, researchers took a look at marine bristle worms. Bristle worms sync their spawning seasons to the waning of the moon: Most mating happens under a new moon and almost disappears during full moons.

Yet when the researchers disrupted the bristle worms circadian clocks, their monthly lunar clock still ticked on. Their lunar clocks, however, seemed to affect the timing and power of circadian-based behaviors.

Read more at Discovery News

Humans Not off the Hook for Megafauna Extinction

Did we do it or was it just a coincidence? That’s what two groups of researchers are arguing with regards to the demise of mammoths, sabertooth cats, giant ground sloths, horses and other “megafauna” that roamed the Americas when humans wandered over from Asia.

A team of Australian scientists led by Chris Johnson of the University of Tasmania is arguing that there are serious flaws in recent work by two Brazilian researchers that exonerates humans. The pair that did that work, Matheus S. Lima-Ribeiro and José Alexandre F. Diniz-Filho of the Universidade Federal de Goiás, have answered that nope, their work isn’t perfect, but still gets humans off the hook.

“They find that in many places megafauna were apparently extinct before humans arrived; in many others, megafauna coexisted with humans for thousands of years before going extinct,” writes Johnson and company in the Oct. 2 issue of the journal Quaternary International. “They conclude that human impact made at most a minor and geographically restricted contribution to megafaunal extinction.”

Johnson argues that the Brazilians’ conclusions are off because they messed up the dating of fossils and extinctions. They re-analyzed the same data and reached the opposite conclusion: the demise of the big animals followed the arrival of humans by about one or two thousand years. That figure meshes with what models predict in terms of how long it would have taken humans to kill and consume so many animals.

But the Brazilians aren’t budging, much.

“…We are…aware that our approach is not necessarily the best, final way, either to deal with such uncertainties or to solve the puzzle of” the megafuana extinctions, the Brazilians responded, in the same issue of the journal. They go on to defend their conclusions and produce yet another analysis of the data that supports their original conclusion: that the timing is wrong for humans to have wiped out all those beasts.

Read more at Discovery News

Causes of Pakistan's New Island Revealed

The powerful earthquake that hit Pakistan on Tuesday (Sept. 24) and killed more than 320 people struck along one of the most hazardous yet poorly studied tectonic plate boundaries in the world.

The magnitude-7.7 earthquake was likely centered on a southern strand of the Chaman Fault, said Shuhab Khan, a geoscientist at the University of Houston. In 1935, an earthquake on the northern Chaman Fault killed more than 30,000 people and destroyed the town of Quetta. It was one of the deadliest quakes ever in Southeast Asia.

Shaking from yesterday's earthquake in Pakistan demolished homes in the Awaran district near the epicenter, according to news reports. The death toll will likely rise as survivors and emergency workers search the debris.

In the hours after the quake, a new island suddenly rose offshore in shallow seas near the town of Gwadar, about 230 miles (380 kilometers) southwest of the epicenter. Geologists with the Pakistan Navy have collected samples from the rocky pile, the Associated Press reported. From pictures and descriptions, many scientists think the mound is a mud volcano, which often erupt after strong earthquakes near the Arabian Sea. A second island has also been reported offshore of Ormara, about 170 miles (280 km) east of Gwadar, Geo News said.

"Other mud volcanoes have been triggered at this distance for similar size earthquakes," Michael Manga, a geophysicist and expert on mud volcanoes at the University of California, Berkeley, told LiveScience's OurAmazingPlanet.

Little known risk

The unexplained island may have focused unusual global attention on the earthquake, which hit in a region that frequently experiences devastating temblors.

But despite the hazards faced by millions living near the Chaman Fault, a combination of geography and politics means the seismic zone remains little studied. The Taliban killed 10 climbers, including an American, in northern Pakistan in June.

"Its location is in an area that is very difficult to do any traditional field work," Khan told LiveScience's OurAmazingPlanet. "I tried twice to submit proposals to (the National Science Foundation) and I got excellent reviews, but the review panel said I was risking my life to work in that area."

But the National Academy of Sciences felt differently. With their support, Khan and his colleagues in Pakistan and at the University of Cincinnati are now studying the fault's current and past movement. This will help the researchers forecast future earthquake risk.

"This fault has had very little work and no paleoseismology," Khan said. "It is really important."

Complex collision zone
Pakistan's deadly earthquakes owe their birth to the juncture of three colliding tectonic plates: Indian, Eurasian and Arabian. The Indian and Eurasian plates grind past each other along the Chaman Fault, triggering destructive temblors.

Earthquakes along the Chaman Fault are more frequent in the north than in the south, Khan said. Similar to California's San Andreas Fault or Turkey's East Anatolian Fault, in some spots, the massive plate boundary is not a single fracture. In southern Pakistan, the Chaman Fault splits into more than one strand, weaving a braid of many smaller faults. The differences between north and south influence the number of earthquakes.

In the past 40 years, only one quake bigger than magnitude 6.0 has jiggled southern Pakistan within 125 miles (200 km) of yesterday's shaker, according to the Incorporated Research Institutions for Seismology in Seattle.

Altogether, the strike-slip Chaman Fault spans more than 500 miles (860 kilometers), crossing through Afghanistan and Pakistan. Strike-slip faults move each side of the fracture mostly parallel to each other.

In the north, near the town of Chaman where India jabs a knuckle into Pakistan, the fault has zipped along at 33 millimeters (1.3 inches) every year for the past 38,000 years, according to a study Khan's team published Sept. 12 in the journal Tectonophysics.

"That is very fast," Khan said. "That tells me there were multiple major earthquakes in the last 38,000 years."

Many mud volcanoes

The ongoing tectonic crash in Pakistan also helps create the mud volcanoes that pop up after earthquakes there. "Whenever there is a major earthquake there are mud volcanoes," Khan said.

The spectacular mountains and roaring rivers of the Pamirs and the Himalayas deliver huge piles of wet silt and mud to the Arabian Sea. Jiggling these wet, gassy layers triggers an eruption of trapped water, Manga said. Think of liquefaction — when saturated soil loses its strength — but on a titanic scale.

The gray, dome-shaped mass offshore of Gwadar is 60 feet (18 meters) high, 100 feet (30 m) long and 250 feet (76 m) wide, a geologist with the Pakistan Navy told Geo News.

Stones on top of the pile suggest the muck roared out of the sea fast enough to carry solid rock.

Read more at Discovery News

Earth Had Oxygen Much Earlier Than Thought

Oxygen may have filled Earth's atmosphere hundreds of millions of years earlier than previously thought, suggesting that sunlight-dependent life akin to modern plants evolved very early in Earth's history, a new study finds.

The findings, detailed in the Sept. 26 issue of the journal Nature,have implications for extraterrestrial life as well, hinting that oxygen-generating life could arise very early in a planet's history and potentially suggesting even more worlds could be inhabited around the universe than previously thought, the study's authors said.

It was once widely assumed that oxygen levels remained low in the atmosphere for about the first 2 billion years of Earth's 4.5-billion-year history. Scientists thought the first time oxygen suffused the atmosphere for any major length of time was about 2.3 billion years ago in what is called the Great Oxidation Event. This jump in oxygen levels was almost certainly due to cyanobacteria — microbes that, like plants, photosynthesize and exhale oxygen.

However, recent research examining ancient rock deposits had suggested that oxygen may have transiently existed in the atmosphere 2.6 billion to 2.7 billion years ago.

The new study pushes this boundary back even further, suggesting Earth's atmosphere became oxygenated about 3 billion years ago, more than 600 million years before the Great Oxidation Event. In turn, this suggests that something was around on the planet to put that oxygen in the atmosphere at this time.

"The fact oxygen is there requires oxygenic photosynthesis, a very complex metabolic pathway, very early in Earth's history," said researcher Sean Crowe, a biogeochemist at the University of British Columbia in Vancouver. "That tells us it doesn't take long for biology to evolve very complex metabolic capabilities."

Ancient oxygen reactions

Crowe and his colleagues analyzed levels of chromium and other metals in samples from South Africa that could serve as markers of reactions between atmospheric oxygen and minerals in Earth's rocks. They looked at both samples of ancient soil and marine sediments from about the same time period — 3 billion years ago.

The researchers focused on the different levels of chromium isotopes within their samples. Isotopes are variants of elements; all isotopes of an element have the same number of protons in their atoms, but each has a different number of neutrons — for instance, each atom of chromium-52 has 28 neutrons, while atoms of chromium-53 have 29.

When atmospheric oxygen reacts with rock, a process known as weathering, heavier chromium isotopes, such as chromium-53, often get washed out to sea by rivers. This means heavier chromium isotopes are often depleted from soils on land and enriched in sediments in the ocean when oxygen is around. These proportions of heavier chromium were just what were seen in the South African samples. Similar results were seen with other metals, such as uranium and iron, that hint at the presence of oxygen in the atmosphere.

"We now have the chemical tools to detect trace atmospheric gases billions of years ago," Crowe told LiveScience.

'Almost certainly biological'

All in all, the researchers suggest atmospheric oxygen levels 3 billion years ago were about 100,000 times higher than what can be explained by regular chemical reactions in Earth's atmosphere. "That suggests the source of this oxygen was almost certainly biological," Crowe said.

Read more at Discovery News