The boardwalk at Pa-hay-okee Overlook is a brief, winding path into a dreamworld in Everglades National Park. Beyond the wooden slats, an expanse of gently waving saw grass stretches to the horizon, where it meets an iron-gray sky. Hardwood tree islands — patches of higher, drier ground called hammocks — rise up from the prairie like surfacing swimmers. The rhythmic singing of cricket frogs is occasionally punctuated by the sharp call of an anhinga or a great egret.

And through this ecosystem, a vast sheet of water flows slowly southward toward the ocean.

The Everglades, nicknamed the river of grass, has endured its share of threats. Decades of human tinkering to make South Florida an oasis for residents and a profitable place for farmers and businesses has redirected water away from the wetlands. Runoff from agricultural fields bordering the national park causes perennial toxic algal blooms in Florida’s coastal estuaries.

But now, the Everglades — home to alligators and crocodiles, deer, bobcats and the Florida panther, plus a dizzying array of more than 300 bird species — is facing a far more relentless foe: rising seas.

South Florida is ground zero when it comes to sea level rise in the United States. By 2100, waters near Key West are projected to be as much as two meters above current mean sea level. Daily high tides are expected to flood many of Miami’s streets. The steady encroachment of saltwater is already changing the landscape, killing off saw grass and exposing the land to erosion.

Against this looming threat, Everglades ecologists and hydrogeologists are racing to find ways to mitigate the damage before the land is reclaimed by the ocean, irrevocably lost.

Sea level rise is a global problem, but coastal water management in South Florida faces some particular challenges, as a 2014 National Climate Assessment report noted. Growing urban centers need access to freshwater, flat topography encourages ponds of water to linger, and porous limestone aquifers are particularly vulnerable to encroaching saltwater. Storm surges occasionally drive seawater far inland, compounding the problem.

“We can’t ignore it anymore,” says Shimelis Dessu, a hydrogeologist at Florida International University in Miami. When it comes to water management needs in South Florida, ecological conservation has tended to be low on the list, compared with human and agricultural needs, Dessu says. Now, sea level rise is forcing people to think differently. “The ocean is no longer an external thing,” he says. “It’s already in the house.”
Draining the swamp
Florida’s tug-of-war over water has a long history.

In the 1800s, settlers first began draining the land to make way for agriculture and communities. Water management in the state began in earnest in 1948, when the U.S. Congress authorized the Central and Southern Florida Project for Flood Control and Other Purposes.

That project was meant to control flooding along the Kissimmee River and Lake Okeechobee, in the south-central part of the state. During the rainy months in summer and fall, the river and the broad, shallow lake often overflowed, flooding surrounding areas. The spillage would travel slowly southward across southern Florida in a broad sheet and eventually drain into Florida Bay, an open water body between the mainland and the Florida Keys. During the journey, some of the water would seep into the ground, replenishing the Biscayne Aquifer, a limestone layer that underlies much of the southeastern part of the state.

But the recurrent flooding made the land uninhabitable and farming impossible. So with Congress’ 1948 authorization, the U.S. Army Corps of Engineers built a complex system of levees, canals and reservoirs to control the floods and channel water away from farmlands south of Lake Okeechobee and from growing population centers. Three large “water conservation areas” were constructed to collect and store water during high rainfall events and release it in times of drought. The remaining wetlands — encompassing about half of their original area — were enclosed into two protected areas, Everglades National Park and Big Cypress National Preserve.

Such an intensive overhaul of South Florida’s water cycle led, perhaps inevitably, to new problems. Reducing the amount of freshwater that naturally heads south into the Everglades proved destructive to the habitats of plants and animals. Wading bird populations, for example, shrank by 90 percent over the last century. Diverting the water away from its natural overland course also meant less water was available to replenish the Biscayne Aquifer, which provides drinking water to 3 million people.

Agriculture is big business in Florida; the state’s exports total more than $4 billion each year. But fertilizer from the agricultural regions pollutes waterways feeding into Lake Okeechobee, causing algal blooms in the lake. Regulated discharges from the lake to control flooding shunt polluted water to the east, west and south, causing periodic algal blooms on the coasts and in Florida Bay.

Hoping to undo some of the damage, Congress approved a 35-year, $10.5 billion project in 2000 to send more freshwater south into the river of grass. That project, the Comprehensive Everglades Restoration Plan, or CERP, remains the largest hydrologic restoration project ever undertaken in the United States.

CERP has shown signs of success. The National Academies of Sciences, Engineering and Medicine, which evaluates the progress of Everglades restoration every two years, reported in 2016 that freshwater flow through the Everglades has indeed increased since the project began. And in some areas, groundwater levels and vegetation are beginning to return to how they looked before the extensive water management began.

But the academy’s 2016 report also pointed to a glaring problem. Researchers know a lot more about the effects of climate change now than they did in 2000. Without accounting for these effects, particularly rising sea levels, the restoration plan will not be able to meet its intended goals: restoring the wetlands and buffering inhabited areas against Florida’s intensely fluctuating hydrologic cycle.

Managed water
Water flow in the Everglades begins with the Kissimmee River and other rivers, which pour into Lake Okeechobee. Left to its natural course (left), the water periodically spilled over the lake’s banks and flowed southward in a broad, shallow sheet (dark blue). But decades of heavy management (center) have channeled the water away from the wetlands to make way for South Florida’s cities and agriculture. The Comprehensive Everglades Restoration Plan (right) aims to restore some of the natural flow while still managing the water.
Source: U.S. Army Corps of Engineers, Jacksonville District

Losing ground
Over the last half-century, the freshwater-saltwater transition zone in the Everglades has moved inland by at least a kilometer, due both to rising sea levels and to the reduction of freshwater flow through the Everglades. Some scientists call this inland shift of saltwater the Anthropocene Marine Transgression, a nod to the fact that humans are ultimately responsible for the rising seas and freshwater management.

In part, it’s a simple problem of water pressure. Freshwater flowing down off the land, or in belowground aquifers, pushes toward the sea. If that tap is slowed to a trickle and freshwater pressure is reduced, the seawater meets less resistance and can drive farther inland. It’s a problem many coastal communities around the world have faced when overdrawing from coastal aquifer wells: Removing too much freshwater at once allowed seawater to sneak in and poison the well. Add rising sea levels to the mix, and the low-lying Everglades face a double hit of saltwater intrusion above ground and below.

Because it is underground, the saltwater intrusion zone is not visible on a map. “But you can see the legacy effect … above ground,” says wetland ecologist Stephen Davis of the Everglades Foundation, a nonprofit group based in Palmetto Bay, Fla. “The salinity periodically knocks back the plant community.”

Hardest hit is the ubiquitous saw grass. Saw grass is hardy stuff; it is resistant to wildfires and thrives even in nutrient-poor soil. But saltwater is another matter. In 2000, a team of scientists surveyed the southernmost portion of the Everglades from the air. The researchers noted odd pockmarks dotting the land — bare patches where the saw grass had died. “Some of these landscapes look like Swiss cheese,” Davis says.
Thick, organic peat soil is the building block of many wetlands, including the Everglades, says Fred Sklar, director of the South Florida Water Management District’s Everglades division, based in West Palm Beach. But peat soil is fragile: Too little freshwater and it dries up. And worse, the combination of dwindling freshwater and increasing saltwater inundation is a one-two punch, “a kind of turbo boost, allowing the soil to break down,” Davis says. Chemical or biological changes within the peat soil — scientists aren’t sure exactly what — then trigger a sudden collapse. Soil elevation drops rapidly, exposing the roots of the saw grass, which eventually die.

The bare patches of ground are the most visible scars of saltwater intrusion, but the extent of the damage is probably much greater than is visually apparent, Davis says. Storm surges from hurricanes such as 2017’s Irma, along with king tide events, the highest high tides of the year, can push saltwater several kilometers inland. As a result, many regions that look fine to the eye are destabilizing beneath the surface, on the verge of collapse, he says.

Widespread peat collapse could be devastating to the Everglades on two fronts. Maintaining the elevation of the soil is a bulkhead against seawater intrusion; the collapsed areas become zones of open water. And peat-filled wetlands represent a vast carbon sink — a region where far more carbon dioxide is absorbed through photosynthesis than is released through respiration. Losing the soil effectively changes the region from a place that stores carbon to one that adds carbon dioxide to the atmosphere, fueling climate change.

Researchers don’t yet know how quickly land is subsiding in the Everglades. But research suggests that even slightly salty waters could cause the soil to sink at a “potentially staggering” rate, Davis says, dramatically increasing how quickly rising seas will be able to reclaim land. Biologist Sean Charles of Florida International University infused plots of saw grass–bearing peat soil with brackish water (still much less salty than seawater). In just one year, soil elevation in the salty plots sank by almost three centimeters, while the soil in the freshwater plots held its elevation or increased slightly.

A tale of two field sites
There’s a second boardwalk at Pa-hay-okee, which gets its name from a Native American word for “grassy waters.” Unlike the visitors’ overlook, getting to this platform requires a short, gutsy slog across a few meters of open wetland, possibly under the watchful gaze of an alligator.

That expanse is an intentional deterrent, says Benjamin Wilson, a wetland ecologist at Florida International University. This boardwalk isn’t meant for visitors; it’s for scientists, who built it as part of a long-term research study to try to understand what, exactly, causes peat soil collapse.

About a 20-minute drive to the south, a sister field site near West Lake is hidden behind a forest screen of salt-tolerant mangroves, their roots entangled and exposed, their branches creaking eerily. The two sites sit on either side of the saltwater intrusion zone: Pa-hay-okee is still largely fresh, but West Lake is brackish.

The first phase of the project, led by wetland ecologist Tiffany Troxler of Florida International University, was to figure out where the peat is most vulnerable to sea level rise, now and in the future, using existing well data, geologic maps and computer simulations of sea level rise. The second step — and the reason for studying the paired sites — examined how salinity changes might affect the peat soil and saw grass. “And then we should have a better idea of where saw grass is going to be, and where peat collapse may occur in the future,” Troxler says.

Alongside the boardwalk, the team embedded a dozen Plexiglas tubes right into the marsh. The chambers, each about half a meter in diameter, are open at the bottom and top, but can be twisted open or closed to allow the water to flow freely through them, or to temporarily sequester the chambers from the rest of the wetland.
Many factors can alter soil chemistry. Reduced freshwater flow can dry out the soil briefly, exposing it to oxygen. And seawater seeping up from the phosphorus-rich limestone aquifer below the wetlands brings in an extra supply of the nutrient, which is otherwise in short supply in the Everglades.

Once a month for four years — during wet and dry seasons — team members visited the chambers at both sites, closing them and dosing them with cocktails composed of different amounts of saltwater and nutrients.

“It was fun,” Wilson says cheerfully. Despite the muddy slog, team members chose not to wear full-body waders. “We’re lucky to be in South Florida, where the water never really gets cold.” Then, he pauses. “Well, it can get really miserable,” he acknowledges after a few seconds. Although they didn’t wear waders, the researchers covered up in long-sleeved shirts and pants, even in the summertime, and shielded their faces, despite the stifling heat. “Do you want 100 mosquitoes in your face, or do you want to be sitting in 95-degree humidity, not being able to breathe with these masks on?” he asks rhetorically.

This sometimes grueling work yielded results, as the team tracked how different factors might affect the saw grass ecosystem and peat collapse. Specifically, the researchers assessed changes in how much carbon dioxide the soil released into the atmosphere as a result of added salt and phosphorus, and also tracked changes in saw grass root growth.

A change in microbe activity was another possible culprit in soil collapse. So microbial biologist Shelby Servais of Florida International University examined whether the saltwater increased microbial growth, which could in turn speed breakdown of organic material. It didn’t happen. “What we found is that, in general, salt exposure suppresses activity of the microbial community.”

Even saltwater inundation — by itself — may not be causing the soil breakdown, Wilson says. What really seemed to matter was how dry the soil was to begin with, before saltwater was added. When the soil was already wet, adding more salt had no effect on how much carbon dioxide the soil released to the atmosphere, the team found. But when the researchers added salt to dry soil, carbon dioxide spiked. The team also noticed that saw grass plants grew fewer roots.

A third phase of the peat soil project is now getting underway. The researchers will precisely track where soil elevation has dropped, and by how much. The team will plunge a rod into the ground all the way to the bedrock and use pins attached to the rod to measure elevation changes over time. From that, Troxler says, “you can get an idea of whether [soil creation in] the wetlands is keeping up with sea level rise.”
Race against the rise
What should planners do if, as some simulations suggest, sea level rise is already outpacing the efforts by state and federal authorities to restore freshwater flow through the Everglades?

Dessu and colleagues took a close look at freshwater management efforts side by side with projections of sea level rise. “We have some control over the freshwater management. The other side, the sea level rise, we don’t have any control over,” he says.

The researchers had about 16 years’ worth of data on changing ecology in the wetlands, including information about the transitions of freshwater saw grass to salt-tolerant mangroves, loss of tree islands and proliferations of water- and nutrient-loving cattail plants. The team analyzed these changes, as well as changes in salinity and nutrients measured in wells in the region, to observe which areas had become saltier over time.
Then, Dessu says, the researchers examined freshwater management practices. Since 1985, South Florida water managers have been gauging how much freshwater to release from the water conservation areas based on the amount of rainfall that fell 10 weeks earlier. In the dry season, that delay is a problem, the team reported in April in the Journal of Environmental Management.

“By the time the flow is delivered, it’s two months too late,” Dessu says. The study concluded that the state’s water managers should consider not just how much water to send down into the Everglades, but when, exactly, would be the best time to do it. “That actually was kind of a surprise,” says Florida International University hydrogeologist René Price, a study coauthor.

Managers can use the difference between measured freshwater level and seawater level to decide when best to deliver a plug of freshwater to maintain enough water pressure to help push seawater back, Dessu says. It’s a kind of Band-Aid fix — one that won’t solve the long-term problem of saltwater encroachment into the wetlands, but may at least ameliorate its immediate effects, he adds.

The future of the Everglades
Such fixes are, perhaps, the story of Everglades restoration. In fact, restoration is a misnomer, Sklar notes. “It’s not really possible to bring back the past.”

Rehabilitation is more to the point. In March, Sklar and other South Florida water managers proposed an ambitious plan that could increase the overall flow of freshwater to the Everglades. The plan centers around the construction of a vast new water reservoir that would collect much of the fertilizer-polluted water from Lake Okeechobee to keep it from running to the coasts where it stimulates algal blooms. Within the reservoir, the water would be scrubbed, then sent to the wetlands. If the U.S. Army Corps of Engineers approves the project, it will become part of legislation headed to Congress in the fall for approval, Sklar says.

The Everglades water managers are walking a tightrope, juggling the needs of residents, farmers and business leaders who want a say about where the water goes. Conservationists in Florida understand this all too well. “If we made it all about climate change and sea level rise, there are those that wouldn’t be receptive,” Davis says. “So we talk about … issues like water supply and making the system more drought resilient.”

“Let’s face it,” he adds. “Science is incredibly important in shaping Everglades restoration projects, but it’s politics that gets the projects authorized and ultimately built.” But he notes that researchers still have many questions about how best to save the Everglades. For example, Davis says, scientists are just beginning to examine whether increasing freshwater flow can even save the saw grass.

Too much freshwater might, in fact, be a cure that’s worse than the disease. “There are models out there that show if we continue to release more freshwater to stem the tide of saltwater, it will end up just flooding the Everglades,” Price says, pointing to the push and pull. “We want to save the freshwater system, but how much flooding can it stand?”

In fact, the best hope for Everglades rehabilitation may be the mangroves. The gnarled, salt-tolerant trees are a visible sign of how the ecosystem is already changing, as they steadily march into regions vacated by freshwater saw grass.

Mangroves colonize new areas as their seeds wash inland. When the seeds settle into a spot, the plants can begin to grow, rapidly producing an abundance of fine roots — the primary component of peat soil. The trees can’t prevent all inundation or save the freshwater plants, but they may, at least, be able to keep the soil in place.

But as with so much in the Everglades, it’s a question of timing, Price says. Mangroves can’t move in if the soil is already completely gone. The trees need enough sediment to establish a foothold. Once established, however, mangroves can build up soil quickly, perhaps even at a pace that matches sea level rise.

“If they don’t, the peat collapse will take over,” Price says. “And it’ll just turn to open water.”
This story appears in the August 18, 2018 issue of Science News with the headline, “Everglades on the Edge: Scientists wrestle with how to fight the effects of sea level rise.”

Scientists have the power to genetically engineer many types of animals. Most Americans think it’s OK to alter or insert genes in animals and insects — provided it’s done in the interest of human health, according to a poll released August 16 from the Pew Research Center. The findings are similar to those from an earlier Pew survey, which found that a majority of Americans are fine with tweaking a baby’s genes, but only if it is to prevent disease.

In the new survey, a majority of respondents support engineering animals for the benefit of human health. For instance, 70 percent approve of preventing the spread of disease by reducing mosquitoes’ fertility (SN Online: 8/5/16), and 57 percent are on board with engineering animals to be organ donors for humans (SN: 11/2/17, p. 15). But people are not as comfortable with genetically manipulating animals for cosmetic or convenience reasons. A majority of respondents — 55 percent — object to genetically tweaking animal to produce more nutritious meat, saying that crosses a line.
The results, based on a survey of 2,537 U.S. adults from April 23 to May 6, reveal the mixed feelings people have about this emerging biotechnology.

Harvesting organs
Of the 41 percent opposed to genetically engineering animals to grow organs or tissue for human transplant, 21 percent said they worried about harm to the animals. Only 16 percent said they were worried about potential human health risks.

Extinct means extinct
Bringing species back from extinction didn’t sit well with 67 percent of respondents, who balked at the idea of altering a living species to revive one no longer in existence (SN: 10/28/17, p. 28). Of that group,18 percent said species are extinct for a reason; 23 percent said it messes with nature or God’s plan; and 14 percent said it’s a waste of resources. Only 4 percent said they were afraid it would create a “Jurassic Park scenario,” in which the de-extinct animals would run amok and kill people.

No to the glow
Engineering aquarium fish to make them glow got the thumbs down from 77 percent of respondents, who gave a variety of reasons: 48 percent of that group said it was a waste of resources, including 23 percent who said it offered no benefit to people or the fish and 13 percent who called it “frivolous.” Only 2 percent worried about how the fish could affect ecosystems if they were released into the wild.

Messing with mosquitoes
Though a majority supported engineering mosquitoes to improve public health, 29 percent disapproved. Of those, 23 percent worried about potential effects on other species, 23 percent were concerned about upsetting nature’s balance and 18 percent mentioned unintended consequences. Only 2 percent expressed worry about making mosquitoes extinct.

The Puerto Rican government has officially updated its tally of lives lost to Hurricane Maria to an estimated 2,975. That number, reported August 28 in a government-commissioned study by George Washington University in Washington D.C., dwarfs the island’s previous count of 64, which officials later acknowledged was far too low.

The study covers September 2017 through February 2018 — two months longer than other recent estimates for the post-hurricane death toll (SN Online: 8/2/18). An absence of clear guidelines for how to certify deaths during a disaster, the researchers found, meant many death certificates didn’t reflect the role of the Category 5 storm, which hit the island on September 20, 2017.
Based on mortality data including death certificates, the new 2,975 estimate falls between two other recent counts. One study in May estimated 4,645 deaths from the hurricane through December 2017 by surveying nearly 3,300 randomly selected households in January and February (SN Online: 5/29/18). Another study in August counted 1,139 excess deaths during the same period, by analyzing and comparing monthly death counts from January 2010 through December 2017.

In a report to Congress, a draft of which was published in July, Puerto Rican officials unofficially acknowledged that the death toll was likely far higher than 64, based on its counting roughly 1,427 more deaths in the four months after the storm than in the same period in the previous four years.

While different methodologies have resulted in different death estimates, the new report “highlights that the humanitarian crisis in Puerto Rico continued until February 2018,” says Alexis Santos, a demographer at Penn State University who was not involved in the new report but was a coauthor of the August study. “All we can do is try to help those still suffering in Puerto Rico.”

A new artificial intelligence is turning its big brain to mapping earthquake aftershocks.

Scientists trained an artificial neural network to study the spatial relationships between more than 130,000 main earthquakes and their aftershocks. In tests, the AI was much better at predicting the locations of aftershocks than traditional methods that many seismologists use, the team reports in the Aug. 30 Nature.

Although it’s not possible to predict where and when an earthquake will happen, seismologists do know a few things about aftershocks. “We’ve known for a long time that they will cluster spatially and decay over time,” says geophysicist Susan Hough of the U.S. Geological Survey in Pasadena, Calif., who was not an author on the new study.
Then, in 1992, a series of temblors prompted a flurry of interest in trying to map out where exactly an aftershock might occur, based on how a mainshock might shift stresses on other faults. First, a magnitude 7.3 earthquake shook the Southern California town of Landers and other nearby desert communities. Three hours later, a magnitude 6.5 aftershock struck the more populous area of Big Bear, about 35 kilometers away. The next day, a magnitude 5.7 aftershock struck near Yucca Mountain, Nev., nearly 300 kilometers away.

“After 1992, people were looking to understand [aftershock] patterns in more detail,” Hough says. Researchers began trying to distill the complicated stress change patterns using different criteria. The most used criterion, the “Coulomb failure stress change,” depends on fault orientations.

But fault orientations in the subsurface can be as complicated as a three-dimensional crazy quilt, and stresses can push on the faults from many different directions at once. Imagine a book sitting on a table: Shear stress pushes the book sideways, and might cause it to slide to the left or right. Normal stress pushes downward on the book, perpendicular to the table, so that it wouldn’t budge. Such a thorny computational problem may be tailor-made for a neural network, Hough says.
Earthquake scientist Phoebe DeVries of Harvard University and colleagues, including a Cambridge, Mass.–based team from Google AI, fed data on more than 130,000 mainshock-aftershock pairs into an AI. Those data included not only locations and magnitudes, but also different measures of changes in stress on the faults from the quakes. The AI learned from the data to determine how likely an aftershock was to occur in a given place, and then the team tested how well the system could actually pinpoint aftershock locations using data from another 30,000 mainshock-aftershock pairs.

The artificial intelligence system consistently predicted aftershock locations much better than the Coulomb failure criterion, the researchers found. That’s because the AI’s results were strongly correlated with other measures of stress change, such as the maximum amount of change in shear stress on a fault, the scientists say.

“It’s a cool study and might pave the way for future work to improve forecasting,” Hough says. But the study focuses just on static stresses, which are permanent shifts in stress due to a quake. Aftershocks may also be triggered by a more ephemeral source of stress known as dynamic stress, produced by a quake’s rumbling through the ground, she says.

Another question is whether a forecast system that used such an AI could leap into action quickly enough after a quake for its aftershock predictions to be helpful. The predictions in the new study benefited from a lot of information about which faults slipped and by how much. In the immediate aftermath of a big quake, such data wouldn’t be available for at least a day.

Using a neural network to study the aftershock problem “is a really nice, efficient approach,” says seismologist Lucy Jones of Caltech and the founder of the Dr. Lucy Jones Center for Science and Society, based in Los Angeles (SN: 3/31/18, p. 26).

But she agrees with Hough that, to help with risk management, the system would need to be able to respond more rapidly. The rule of thumb is that “whatever number of aftershocks you have on the first day, you get half of that on the second day, and so on,” says Jones, who was not involved in the new study. “A week after the earthquake, the majority of aftershocks have already happened.”

Power systems transcended kinship in medieval Europe. A burial site in southern Germany contains members of a powerful warrior family who journeyed widely to find recruits to join the household and support a post-Roman kingdom, a new study suggests.

Thirteen individuals interred at Niederstotzingen belonged to the Alemanni, a confederation of Germanic tribes that were conquered by and integrated into a neighboring kingdom of the Frankish people starting around 1,400 years ago, researchers say. Excavations in 1962 revealed the bodies, which the team estimates were buried from roughly 580 to 630, along with various weapons, armor, jewelry, bridle gear and the remains of three horses.
DNA extracted from the German skeletons identified 11 as probably males, biomolecular archaeologist Niall O’Sullivan of Eurac Research’s Institute for Mummy Studies in Bolzano, Italy, and colleagues report online September 5 in Science Advances. Six skeletons displayed genetic ties to modern northern and eastern Europeans. All but one of those six were closely related, including a father and two of his sons. Chemical analyses of tooth enamel, which provides regional signals of early childhood diet, indicated that these individuals grew up near Niederstotzingen.

Artifacts from three foreign medieval European cultures lay in the graves of four local males. Weapons and other objects typical of the Franks accompanied one man — the previously mentioned father — who may have headed the power household, the researchers suspect.
Another three individuals buried at the site were genetically unrelated to anyone else. Two possessed DNA like that of present-day Mediterranean people. All had spent their childhoods in other regions, tooth data suggest.

The new results support previous suggestions that, shortly after the Roman Empire’s fall in the fifth century (SN: 4/29/17, p. 18), the Frankish Empire maintained power throughout central Europe for several centuries by establishing mobile, warrior households that enforced obedience to the ruler.

A new hexagon has emerged high in the skies over Saturn’s north pole.

As spring turned to summer in the planet’s northern hemisphere, a six-sided vortex appeared in the stratosphere. Surprisingly, the polar polygon seems to mirror the famous hexagonal cyclone that swirls in the clouds hundreds of kilometers below, researchers report online September 3 in Nature Communications.

When NASA’s Cassini spacecraft arrived at Saturn in 2004 — during summer in the southern hemisphere — the probe spied a similar vortex in the stratosphere over the south pole, though that one was shaped more like a plain old circle. As summer gradually turned to autumn, that vortex vanished.
Now, planetary scientist Leigh Fletcher at the University of Leicester in England and colleagues report that Cassini caught a new vortex growing in the north during the spacecraft’s final years. Relying on infrared maps of the atmosphere, the team found that from 2014 to 2017 a warm, swirling mass of air started developing over the north pole. That wasn’t surprising — but the six-sided shape came as a bit of a shock.

The shape suggests that the underlying hexagon somehow controls what happens in the stratosphere. These sorts of insights could help researchers understand how energy moves around in other planetary atmospheres.

Unfortunately, Cassini is no longer around — it dove into Saturn last year (SN: 9/2/17, p. 16). But Earth-based telescopes will keep an eye on the storm to see how it changes along with Saturn’s seasons.

For sale: Pristine lake. Price negotiable.

Most U.S. government attempts to quantify the costs and benefits of protecting the country’s bodies of water are likely undervaluing healthy lakes and rivers, researchers argue in a new study. That’s because some clean water benefits get left out of the analyses, sometimes because these benefits are difficult to pin numbers on. As a result, the apparent value of many environmental regulations is probably discounted.

The study, published online October 8 in the Proceedings of the National Academy of Sciences, surveyed 20 government reports analyzing the economic impacts of U.S. water pollution laws. Most of these laws have been enacted since 2000, when cost-benefit analyses became a requirement. Analysis of a measure for restricting river pollution, for example, might find that it increases costs for factories using that river for wastewater disposal, but boosts tourism revenues by drawing more kayakers and swimmers.
Only two studies out of 20 showed the economic benefits of these laws exceeding the costs. That’s uncommon among analyses of environmental regulations, says study coauthor David Keiser, an environmental economist at Iowa State University in Ames. Usually, the benefits exceed the costs.

So why does water pollution regulation seem, on paper at least, like such a losing proposition?

Keiser has an explanation: Summing up the monetary benefits of environmental policies is really hard. Many of these benefits are intangible and don’t have clear market values. So deciding which benefits to count, and how to count them, can make a big difference in the results.
Many analyses assume water will be filtered for drinking, Keiser says, so they don’t count the human health benefits of clean lakes and rivers (SN: 8/18/18, p. 14). That’s different from air pollution cost-benefit studies, which generally do include the health benefits of cleaner air by factoring in data tracking things like doctor’s visits or drug prescriptions. That could explain why Clean Air Act rules tend to get more favorable reviews, Keiser says — human health accounts for about 95 percent of the measured benefits of air quality regulations.

“You can avoid a lake with heavy, thick, toxic algal blooms,” Keiser says. “If you walk outside and have very polluted air, it’s harder to avoid.”

But even if people can avoid an algae-choked lake, they still pay a price for that pollution, says environmental scientist Thomas Bridgeman, director of the Lake Erie Center at the University of Toledo in Ohio.
Communities that pull drinking water from a lake filled with toxic blooms of algae or cyanobacteria spend more to make the water safe to drink. Bridgeman’s seen it firsthand: In 2014, Lake Erie’s cyanobacteria blooms from phosphorus runoff shut down Toledo’s water supply for two days and forced the city to spend $500 million on water treatment upgrades.

Most of the studies surveyed by Keiser and his team were missing other kinds of benefits, too. The reports usually left out the value of eliminating certain toxic and nonconventional pollutants — molecules such as bisphenol A, or BPA, and perfluorooctanoic acid, or PFOA (SN: 10/3/15, p. 12). In high quantities, these compounds, which are used to make some plastics and nonstick coatings, can cause harm to humans and wildlife. Many studies also didn’t include discussion of how the quality of surface waters can affect groundwater, which is a major source of drinking water for many people.

A lack of data on water quality may also limit studies, Keiser’s team suggests. While there’s a national database tracking daily local air pollution levels, the data from various water quality monitoring programs aren’t centralized. That makes gathering and evaluating trends in water quality harder.

Plus, there are the intangibles — the value of aquatic species that are essential to the food chain, for example.
“Some things are just inherently difficult to put a dollar [value] on,” says Robin Craig, an environmental law professor at the University of Utah in Salt Lake City. “What is it worth to have a healthy native ecosystem?… That’s where it can get very subjective very fast.”

That subjectivity can allow agencies to analyze policies in ways that suit their own political agendas, says Matthew Kotchen, an environmental economist at Yale University. An example: the wildly different assessments by the Obama and Trump administrations of the value gained from the 2015 Clean Water Rule, also known as the Waters of the United States rule.

The rule, passed under President Barack Obama, clarified the definition of waters protected under the 1972 Clean Water Act to include tributaries and wetlands connected to larger bodies of water. The Environmental Protection Agency estimated in 2015 that the rule would result in yearly economic benefits ranging from $300 million to $600 million, edging out the predicted annual costs of $200 million to $500 million. But in 2017, Trump’s EPA reanalyzed the rule and proposed rolling it back, saying that the agency had now calculated just $30 million to $70 million in annual benefits.

The difference in the conclusions came down to the consideration of wetlands: The 2015 analysis found that protecting wetlands, such as marshes and bogs that purify water, tallied up to $500 million in annual benefits. The Trump administration’s EPA, however, left wetlands out of the calculation entirely, says Kotchen, who analyzed the policy swing in Science in 2017.

Currently, the rule has gone into effect in 26 states, but is still tied up in legal challenges.

It’s an example of how methodology — and what counts as a benefit — can have a huge impact on the apparent value of environmental policies and laws.

The squishiness in analyzing environmental benefits underlies many of the Trump administration’s proposed rollbacks of Obama-era environmental legislation, not just ones about water pollution, Kotchen says. There are guidelines for how such cost-benefit analyses should be carried out, he says, but there’s still room for researchers or government agencies to choose what to include or exclude.

In June, the EPA, then under the leadership of Scott Pruitt, proposed revising the way the agency does cost-benefit analyses to no longer include so-called indirect benefits. For example, in evaluating policies to reduce carbon dioxide emissions, the agency would ignore the fact that those measures also reduce other harmful air pollutants. The move would, overall, make environmental policies look less beneficial.

These sharp contrasts in how presidential administrations approach environmental impact studies are not unprecedented, says Craig, the environmental law professor. “Pretty much every time we change presidents, the priorities for how to weigh those different elements change.”

Flying forward is hard enough, but flying nowhere, just hovering, is so much harder. Most bats and birds can manage the feat for only a few frantic seconds.

Hovering means losing a useful aerodynamic shortcut, says aerospace engineer and biologist David Lentink of Stanford University. As a bat or bird flies forward, its body movement sends air flowing around the wings and providing some cheap lift. For animals on the scale of bats and birds, that’s a big help. Without that boost, “you’re going to have to move all the air over your wings by moving it with your wings,” he says. The energy per second you’re consuming to stay in place by flapping your wings back and forth like a hummingbird “is gigantic.”
So how do vertebrates in search of nectar, for whom a lot of energy-sucking hovering is part of life, manage the job? For the first direct measurements of the wingbeat forces that make hovering possible, Lentink’s Ph.D. student Rivers Ingersoll spent three years creating a flight chamber with exquisitely responsive sensors in the floor and ceiling. As a bird or bat hovers inside, the sensors can measure — every 200th of a second — tremors even smaller than a nanometer caused by air from fluttering wings. Once the delicate techno-marvel of an instrument was perfected, the researchers packed it into 11 shipping cases and sent it more than 6,000 kilometers to the wilds of Costa Rica.
“Very difficult,” Ingersoll acknowledges. The Las Cruces Research Station is great for field biology, but it’s nothing like a Stanford engineering lab. Every car turning into the station’s driveway set off the wingbeat sensors. And even the special thick-walled room that became the machine’s second home warmed up enough every day to give the instrument a fever.
Babying the instrument as best he could, Ingersoll made direct measurements for 17 hovering species of hummingbirds and three bats, including Pallas’s long-tongued bats (Glossophaga soricina). “Their up-pointy noses made me think of rhino faces,” he says.
Pallas’s bats specialize in nectar sipping much as hummingbirds do. Comparing wingbeats, bat vs. bird, revealed differences, though. Hummers coupled powerful downstrokes and recovery upstrokes that twist part of the wings almost backward. The twist supplied about a quarter of the energy it takes to keep a bird aloft, the researchers report in the September 26 Science Advances. The two kinds of nectar bats got a little more lift from the upstroke than did a bat that eats fruit instead of strenuously hovering for nectar. Yet even the specialist nectar bats relied mostly on downstrokes: powerful, deeply angled downstrokes of really big wings.

Those bat wings span proportionally more area than hummer wings. So the bats get about the same hovering power per gram of body weight that hummingbirds do. Supersizing can have its own kind of high-tech design elegance.

SAN DIEGO — A sleepless night can leave the brain spinning with anxiety the next day.

In healthy adults, overnight sleep deprivation triggered anxiety the next morning, along with altered brain activity patterns, scientists reported November 4 at the annual meeting of the Society for Neuroscience.

People with anxiety disorders often have trouble sleeping. The new results uncover the reverse effect — that poor sleep can induce anxiety. The study shows that “this is a two-way interaction,” says Clifford Saper, a sleep researcher at Harvard Medical School and Beth Israel Deaconess Medical Center in Boston who wasn’t involved in the study. “The sleep loss makes the anxiety worse, which in turn makes it harder to sleep.”
Sleep researchers Eti Ben Simon and Matthew Walker, both of the University of California, Berkeley, studied the anxiety levels of 18 healthy people. Following either a night of sleep or a night of staying awake, these people took anxiety tests the next morning. After sleep deprivation, anxiety levels in these healthy people were 30 percent higher than when they had slept. On average, the anxiety scores reached levels seen in people with anxiety disorders, Ben Simon said November 5 in a news briefing.

What’s more, sleep-deprived people’s brain activity changed. In response to emotional videos, brain areas involved in emotions were more active, and the prefrontal cortex, an area that can put the brakes on anxiety, was less active, functional MRI scans showed.

The results suggest that poor sleep “is more than just a symptom” of anxiety, but in some cases, may be a cause, Ben Simon said.

Some moths aren’t so easy for bats to detect.

The cabbage tree emperor moth has wings with tiny scales that absorb sound waves sent out by bats searching for food. That absorption reduces the echoes that bounce back to bats, allowing Bunaea alcinoe to avoid being so noticeable to the nocturnal predators, researchers report online November 12 in the Proceedings of the National Academy of Sciences.

“They have this stealth coating on their body surfaces which absorbs the sound,” says study coauthor Marc Holderied, a bioacoustician at the University of Bristol in England. “We now understand the mechanism behind it.”

Bats sense their surroundings using echolocation, sending out sound waves that bounce off objects and return as echoes picked up by the bats’ supersensitive ears (SN: 9/30/17, p. 22). These moths, without ears that might alert them to an approaching predator, have instead developed scales of a size, shape and thickness suited to absorbing ultrasonic sound frequencies used by bats, the researchers found.
The team shot ultrasonic sound waves at a single, microscopic scale and observed it transferring sound wave energy into movement. The scientists then simulated the process with a 3-D computer model that showed the scale absorbing up to 50 percent of the energy from sound waves.

What’s more, it isn’t just wings that help such earless moths evade bats. Other moths in the same family as B. alcinoe also have sound-absorbing fur, the same researchers report online October 18 in the Journal of the Acoustical Society of America.
Holderied and his colleagues studied the fluffy thoraxes of the Madagascan bullseye moth and the promethea silk moth, and found that the fur also absorbs sound waves through a different process called porous absorption. In lab tests, the furry-bellied moths absorbed as much as 85 percent of the sound waves encountered. Researchers suspect that the equally fluffy cabbage tree emperor moth also has this ability.

Other moths that have ears can hear bats coming, and can quickly swerve out of the way of their predators, dipping and diving in dizzying directions (SN: 5/26/18, p. 11). Some moths also have long tails on their wings that researchers suspect can be twirled to disrupt bats’ sound waves (SN: 3/21/15, p. 17). Still other moths produce toxins to fend off foes.

Having sound-absorbent fur and scales “might require a lot less energy in terms of protection from the moth’s side,” says Akito Kawahara, an evolutionary biologist at the Florida Museum of Natural History in Gainesville who was not involved with the study. “It’s a very different kind of passive defense system.”

Holderied and his colleagues hope next to study how multiple scales, locked together, respond to ultrasonic sound waves. The findings could one day help in developing better soundproofing technology for sound engineers and acousticians.