November 26, 2013
Seahorses belong to the genus Hippocampus, which gets its name from the Greek words for “horse” and “sea monster.” With their extreme snouts, weirdly coiled bodies and sluggish movements produced by to two puny little fins, these oddly shaped fish seem like an example of evolution gone terribly awry. And yet, new research published today in Nature Communications shows that it is precisely the seahorse’s uncanny looks and slow motions that allow it to act as one of the most stealthy predators under the sea.
Seahorses, like their close relatives the pipefish and sea dragons, sustain themselves by feasting on elusive, spastic little crustaceans called copepods. To do this, they use a method called pivot feeding: they sneak up on a copepod and then rapidly strike before the animal can escape, much like a person wielding a bug swatter tries to do to take out an irritating but otherwise impossible-to-catch fly. But like that lumbering human, the seahorse will only be successful if it is able to get near enough to its prey to strike at very close range. In the water, however, this is an even greater feat than on land because creatures like copepods are extremely sensitive to any slight hydrodynamic change in the currents around them.
So how do those ungainly little guys manage to feed themselves? As it turns out, the seahorse is a more sophisticated predator than appearance might suggest. In fact, it is precisely its looks that make it an ace in the stealth department. To arrive at this surprising conclusion, researchers from the University of Texas at Austin and the University of Minnesota used holographic and particle image velocimetry–fancy ways of visualizing 3D movements and water flow, respectively–to monitor the hunting patterns of dwarf seahorses in the lab.
In dozens of trials, they found that 84 percent of the seahorses’ approaches successfully managed not to sound the copepod’s retreat alarms. The closer the seahorse could get to its unsuspecting prey and the faster it struck, the greater its odds of success, they observed. Once in range of the copepod, seahorses managed to capture those crustaceans 94 percent of the time. Here, you can see that method of attack, in which the seahorse’s giant head looks like a floating bit of marine sludge drifting toward the blissfully ignorant copepod:
The way the seahorse’s movements and morphology–especially its head–interact with the water particles, the researchers found, likely take the credit for its exceptional hunting skill. The animal’s arched neck acts like a spring for generating an explosive strike, they describe, while the shape of its snout–a thin tube with the mouth positioned at the very end–allows it to drift through the water while creating minimal disturbance.
To emphasize this pinnacle of engineering, the team compared water disruptions caused by seahorses with those of sticklebacks, a relative of the seahorse but with a more traditional fishy look. Thanks to the shape and contours of the seahorse’s head, that predator produced significantly less fluid deformation in the surrounding water than the stickleback. The poor stickleback possesses neither the morphology nor posture to generate “a hydrodynamically quiet zone where strikes occur,” the authors describe. In other words, while the seahorse may appear a bit odd so far as fishes go, evolution was obviously looking out for that funny but deadly animal’s best interests.
October 10, 2013
The star GD61 is a white dwarf. As such, it’s insanely dense—similar in diameter to Earth, but with a mass roughly that of the Sun, so that a teaspoon of it is estimated to weigh about 5.5 tons. All things considered, it’s not a particularly promising stellar locale to find evidence of life.
But a new analysis of the debris surrounding the star suggests that, long ago, GD61 may have provided a much more hospitable environment. As part of a study published today in Science, scientists found that the crushed rock and dust near the star were once part of a small planet or asteroid made up of 26 precent water by volume. The discovery is the first time we’ve found water in a rocky, Earth-like planetary body (as opposed to a gas giant) in another star system.
“Those two ingredients—a rocky surface and water—are key in the hunt for habitable planets,” Boris Gänsicke of the University of Warwick in the UK, one of the study’s authors, said in a press statement. “So it’s very exciting to find them together for the first time outside our solar system.”
Why was water found in such a seemingly unhospitable place? Because once upon a time, GD61 wasn’t so different from our Sun, scientists speculate. But roughly 200 million years ago, when it exhausted its supply of fuel and could no longer sustain fusion reactions, its outer layers were blown out as part of a nebula, and its inner core collapsed inward, forming a white dwarf. (Incidentally, this fate will befall an estimated 97 percent of the stars in the Milky Way, including the Sun.)
When that happened, the tiny planet or asteroid in question—along with all the other bodies orbiting GD61—were violently knocked out of orbit, sucked inward, and ripped apart by the force of the star’s gravity. The clouds of dust, broken rock and water that the scientists recently discovered near the star are the remnants of these planets.
Even in its heyday, the watery body was probably still very small—perhaps comparable in size to our solar system’s dwarf planet Ceres, which orbits in the asteroid belt and is about .015 percent the mass of Earth. Additionally, like Ceres, the ancient planet or asteroid was extremely water-rich (26 percent water, far more than Earth’s .023 percent), and this water was similarly constituted as ice locked within a rocky crust.
To find all this out, the group of scientists (which also includes Jay Farihi of the University of Cambridge and Detlev Koester of the University of Kiel) used observations from two sources: a spectrograph on board the Hubble Space Telescope, through which they obtained data on ultraviolet light emitted by GD61, and a telescope at the W.M. Keck Observatory on Mauna Kea on Hawaii.
By looking at the light emitted from the star, which glows in certain patterns depending on the chemical signatures of gases present, they were able to determine the proportions of a number of elements (including oxygen, magnesium, aluminum, silicon, calcium and iron) contained within the cloud of dust that surrounds it. Using computer simulations of this stellar atmosphere, they were able to rule out a number of alternate possibilities that could have accounted for the abundance of oxygen, leaving only the explanation that it was brought there in water form.
Based on the amount of water and rocky minerals detected in the star’s atmosphere—and assuming it all came from one body—scientists speculate that the small planet or asteroid ripped up by the white dwarf was at least 56 miles in diameter, but perhaps much larger.
Although the star certainly isn’t home to any life at the moment due to its relatively cold temperature, the finding makes it seem more likely that other exoplanets contain water, which is necessary for life as we know it. Many scientists have speculated that small planets and asteroids like Ceres delivered water to Earth in the first place, so finding evidence of a watery body like this in another star system raises the possibility that the same process may have brought water to an Earth-sized planet elsewhere too.
“The finding of water in a large asteroid means the building blocks of habitable planets existed—and maybe still exist—in the GD 61 system, and likely also around a substantial number of similar parent stars,” Farihi said. “These water-rich building blocks, and the terrestrial planets they build, may in fact be common.”
October 2, 2013
Editor’s Note, Oct. 9: Based on several comments that mentioned that the Josephine Brine Treatment Facility stopped treating fracking wastewater in 2011, we did a bit of digging and found that the treated water downstream from the plant still showed signatures that fresh fracking water had run through it, according to the study’s authors. The post has been revised with this information, along with the fact that treatment does remove a good bit of contamination.
In the state of Pennsylvania, home to the lucrative Marcellus Shale formation, 74 facilities treat wastewater from the process of hydraulic fracturing (a.k.a. “fracking”) for natural gas and release it into streams. There’s no national set of standards that guides this treatment process—the EPA notes that the Clean Water Act’s guidelines were developed before fracking even existed, and that many of the processing plants “are not properly equipped to treat this type of wastewater”—and scientists have conducted relatively little assessment of the wastewater to ensure it’s safe after being treated.
Recently, a group of Duke University scientists decided to do some testing. They contacted the owners of one treatment plant, the Josephine Brine Treatment Facility on Blacklick Creek in Indiana County, Pennsylvania, but, “when we tried to work with them, it was very difficult getting ahold of the right person,” says Avner Vengosh, an Earth scientist from Duke. “Eventually, we just went and tested water right from a public area downstream.”
Their analyses, made on water and sediment samples collected repeatedly over the course of two years, were even more concerning than we’d feared. As published today in the journal Environmental Science and Technology, they found elevated concentrations of the element radium, a highly radioactive substance. The concentrations within sediments in particular were roughly 200 times higher than background levels. In addition, amounts of chloride and bromide in the water were two to ten times greater than normal.
This is despite the fact that treatment actually removes most of the contaminants from the wastewater–including 90 percent of the radium. “Even if, today, you completely stopped disposal of the wastewater,” Vengosh says, there’s enough contamination built up in sediments that “you’d still end up with a place that the U.S. would consider a radioactive waste site.”
In recent years, the use of fracking to extract natural gas from shale formations has boomed in several areas, most notably Pennsylvania’s Marcellus Shale, which has been called “the Saudi Arabia of natural gas.” The process involves injecting mix of water, sand and proprietary chemicals deep into rock at high pressure, causing the rock to fracture and allowing methane gas to seep upward for extraction.
Much of the concern over fracking has related to the seepage of these chemicals or methane from drilling wells into groundwater or the fact that high-pressure injection can trigger earthquakes, but the wastewater recently tested presents a separate, largely overlooked problem.
Between 10 and 40 percent of fluid sent down during fracking resurfaces, carrying contaminants with it. Some of these contaminants may be present in the fracking water to begin with. But others are leached into the fracking water from groundwater trapped in the rock it fractures.
Radium, naturally present in the shales that house natural gas, falls into the latter category—as the shale is shattered to extract the gas, groundwater trapped within the shale, rich in concentrations of the radioactive element, is freed and infiltrates the fracking wastewater.
Other states require this wastewater to be pumped back down into underground deposit wells sandwiched between impermeable layers of rock, but because Pennsylvania has few of these cavities, it allows fracking wastewater to be processed by normal wastewater treatment plants and released into rivers.
In 2011, Pennsylvania Department of Environmental Protection (PADEP) issued a recommendation that plants, including Josephine, voluntarily stop treating fracking wastewater. But Jim Efstathiou Jr. at Bloomberg News reports that, even though spokespeople at PADEP and Josephine say that the plant has stopped treating fracking wastewater, those claims are “contradicted by today’s study, which shows that the Josephine plant continued to treat Marcellus Shale wastewater through the beginning of this year,” according to Vengosh.
“Based on the isotopes that we measured we can see that the effluent that’s coming from Josephine in the last three years, including two months ago, still has the fingerprint of the Marcellus,” Vengosh told Efsathiou.
The treatment plants, many scientists note, are not designed to handle the radioactive elements present in the wastewater. Neither are they required to test their effluent for radioactive elements. As a result, many researchers have suspected that the barely-studied water they release into local streams retains significant levels of radioactivity.
This new work confirms that suspicion for at least one plant—which as about an hour east of Pittsburgh, and releases effluent into the watershed that supplies the city’s drinking water—and Vengosh believes that the findings would likely be similar for many of the other facilities in Pennsylvania. Especially concerning is the fact that, apart from in the water, the team found high levels of radioactivity accumulating on the sediments at the bottom of the stream over time. Radium has a half-life of 1600 years, so unless these sediments are removed, they’ll keep releasing radiation into the water for an extremely long period.
In addition, the high levels of bromide found in the wastewater is a concern, because even in slight quantities, the compound can trigger the formation of a toxic class of chemicals called halomethanes when it’s combined with chlorine. This is a problem because in rural areas, many residents treat well water by chlorinating it.
The study—which is part of a larger Duke project studying the effect of fracking on water—doesn’t show that fracking is inherently unsafe, but does show that without proper controls, the wastewater being dumped into the environment daily represents a very real danger for local residents.
Vengosh notes that there are better methods of treating fracking wastewater (he points to the plants operated by Eureka Resources as a model for adequately removing radioactivity), but these are more expensive to operate. But currently, without the push of federal regulations, companies looking to dispose of wastewater have no incentive to pay for this type of solution.
September 26, 2013
Some 46 Martian days after landing on Mars in August 2012, after traveling nearly 1,000 feet from its landing site, Curiosity came upon a pyramid-shaped rock, roughly 20 inches tall. Researchers had been looking for a rock to use for calibrating a number of the rover’s high-tech instruments, and as principal investigator Roger Wiens said at a press conference at the time, “It was the first good-size rock that we found along the way.”
For the first time, scientists used the rover’s Hand Lens Imager (which takes ultra-high resolution photos of a rock’s surface) and the Alpha Particle X-ray Spectrometer (which bombards a rock with alpha particles and X-rays, kicking off electrons in patterns that allow scientists to identify the elements locked within it). They also used the ChemCam, a device that fires a laser at a rock and measures the abundances of elements vaporized.
Curiosity, for its part, commemorated the event with a pithy tweet:
I did a science! 1st contact science on rock target Jake. Here’s an action shot pic.twitter.com/pzcgH6Bk
— Curiosity Rover (@MarsCuriosity) September 22, 2012
A year later, the Curiosity team’s analysis of the data collected by these instruments, published today in Science, shows that they made a pretty lucky choice in finding a rock to start with. The rock, dubbed “Jake_M” (after engineer Jake Matijevic, who died a few days after Curiosity touched down), is unlike any rock previously found on Mars—and its composition intriguingly suggests that it formed after molten rock cooled quickly in the presence of underground water.
The new discovery was published as part of a special series of papers in Science that describe the initial geologic data collected by Curiosity’s full suite of scientific instrumentation. One of the other significant findings is a chemical analysis of a scoop of Martian soil—heated to 835 degrees Celsius inside the Sample Analysis at Mars instrument mechanism—showing that it contains between 1.5 and 3 percent water by weight, a level higher than scientists expected.
But what’s most exciting about the series of findings is the surprising chemical analysis of Jake_M. The researchers determined that it is likely igneous (formed by the solidification of magma) and, unlike any other igneous rocks previously found on Mars, has a mineral composition most similar to a class of basaltic rocks on Earth called mugearites.
“On Earth, we have a pretty good idea how mugearites and rocks like them are formed,” Martin Fisk, an Oregon State University geologist and co-author of the paper, said in a press statement. “It starts with magma deep within the Earth that crystallizes in the presence of one to two percent water. The crystals settle out of the magma, and what doesn’t crystallize is the mugearite magma, which can eventually make its way to the surface as a volcanic eruption.” This happens most frequently in underground areas where molten rock comes into contact with water—places like mid-ocean rifts and volcanic islands.
The fact that Jake_M closely resembles mugearites indicates that it likely took the same path, forming after other minerals crystallized in the presence of underground water and the remaining minerals were sent to the surface. This would suggest that, at least at some time in the past, Mars contained reserves of underground water.
The analysis is part of a growing body of evidence that Mars was once home to liquid water. Last September, images taken by Curiosity showed geologic features that suggested the one-time presence of flowing water at the surface. Here on Earth, analyses of several meteorites that originated on Mars have also indicated that, at some point long ago, the planet held reserves of liquid water deep underground.
This has scientists and members of the public excited, of course, because (at least as far as we know) water is a necessity for the evolution of life. If Mars was once a water-rich planet, as Curiosity’s findings increasingly suggest, it’s possible that life may have once evolved there long ago—and there may even be organic compounds or other remnants of life waiting to be found by the rover in the future.
August 1, 2013
Climate change isn’t just affecting the natural world. Researchers have long understood that rising levels of greenhouse gas emissions will also have cascading ramifications on the dynamics of human society, whether by forcing refugees to flee from newly flood-prone areas or arid regions, by causing spikes in the prices of food crops, or by reducing the productivity of livelihoods based on fishing or grazing in certain regions.
Recently, studies and journalistic investigations have focused on one particularly chilling potential social consequence of climate change: an increased frequency of armed conflicts around the world. By studying the link between various climactic factors and rates of historical violence, researchers have speculated that the climate trends we’ll experience over the next century—hotter overall temperatures, more erratic rainfall patterns and a rising sea level—could make conflict and war more common in the future.
Now, in the most comprehensive analysis of the work on climate change and armed conflict to date, a team from UC Berkeley and elsewhere has found that these climate trends are indeed likely to significantly increase the incidence of armed conflict overall. Their paper, published today in Science, examined 60 studies to aggregate sets of data on events spanning 8000 B.C.E. to the present that examined climate variables and incidences of violence in all major regions of the globe. For example, one of the source papers focused on temperature changes and violent crime in the U.S. from 1952 to 2009, while another looked at the number of conflicts in Europe per decade from 1400 to 1999 as a function of precipitation.
Cross-comparing these studies with the same statistical methods revealed patterns that, when projected into future, suggest that by 2050 we could see 50 percent more instances of mass conflict due to the effects of climate change.
The team, led by Solomon Hsiang, specifically looked the historical relationship between climatic factors (temperature and rainfall fluctuations) and the incidence of all sorts of conflicts detailed in their source studies, which they grouped into the categories of personal crime (murder, domestic violence, rape and assault), intergroup violence (civil wars, ethnic violence and riots) and institutional breakdowns (collapses of governing bodies or even of entire civilizations such as the Mayan empire). They examined this relationship on a variety of spatial scales, ranging from countries to regions to even warmer areas within a large building or stadium, and on varying time scales, from months to years to centuries in duration.
To standardize data from many different climates and regions, the researchers calculated the number of standard deviations away from baseline averages that temperatures and rainfall rates shifted in the areas studied by the previous papers, based on the time periods covered. A standard deviation is a statistical tool used to examine how data is clustered about an average—the more standard deviations away from the average you go, the more the observation in question is an outlier.
They found that when temperatures or precipitation patterns in an area strayed from the norm, all three types of violence tended to increase, with intergroup conflict in particular surging the most during hotter periods. Specifically, a region that experienced a period of warming that fell beyond one standard deviation of average conditions saw 4 percent more personal crime and 14 percent more intergroup conflict over the period studied. In other words, assuming the variables fall in a bell curve around from average conditions, life became more violent for the roughly 32 percent of regions that significantly deviated away from average temperatures and precipitation rates.
This level of deviation, to put it into perspective, is equivalent to a country in Africa going through an entire year of temperatures averaging 0.6°F warmer than usual or to a county in the U.S. experiencing average temperatures of 5°F warmer than normal in a given month. “These are moderate changes, but they have a sizable impact on societies,” explained Marshall Burke, the study’s co-lead author and a doctoral candidate at Berkeley’s Department of Agricultural and Resource Economics.
Extrapolating to the future, these rates mean that if the entire planet went through an average of 3.6°F of warming by 2050—an optimistic limit set at the 2009 Copenhagen conference—we’d see personal crime rise by 16 percent and intergroup conflicts surge by 50 percent. The distribution of violence wouldn’t be equal, either, as climate models indicate that some areas will be hit with warming periods that fall outside two, three or even four standard deviations of the norm (and thus experience more conflict), as shown in the map below:
But what characteristics of these climate changes—heat and erratic rainfall—cause people or institutions to become violent? The mechanisms that link climate trends with violence are varied and, in many cases, unclear.
Statistics show that in cities, hotter temperatures lead to more arrests for violent crimes, and some researchers believe our basic physiological stress response to heat is to blame someone or something for the heat—but it’s unclear whether the data represent causation or correlation. On a broader level, it’s believed that reductions in agricultural productivity—especially in largely agrarian societies—can drive intergroup conflict, as can extreme weather events and reductions in resources such as potable water (due to erratic rainfall) and arable land (due to sea level rise). All of these factors are likely to come into play as the climate changes.
Of course, there are a few caveats to the finding. For one, the researchers are extrapolating from historical data, so it’s possible that even though humans have previously become more violent as temperatures increased, we could behave differently in the future. Additionally, these hypotheses can’t be rigorously tested in a lab, so it’s impossible to entirely rule out all confounding factors and establish that the climate trends cause more conflict, rather than coincidentally occurring at the same time.
The researchers, though, say that they conducted the most rigorous analysis possible. The fact that the climate-violence relationship was consistently found among a wide range of time periods, cultures and regions, they argue, indicates that there is a substantial link between the two.
If warmer temperatures and erratic precipitation really do drive violence, what can we do? The researchers say that we need to engage in research to better understand the mechanisms by which this occurs—so that eventually, just as we’ll build infrastructure to anticipate and defend against the brunt of climate change’s most dire effects, we can also create innovative social institutions and policies that might minimize violence in a warming world.