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      A new technique could make some plastic trash compostable at home

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      A pinch of polymer-munching enzymes could make biodegradable plastic packaging and forks truly compostable.

      With moderate heat, enzyme-laced films of the plastic disintegrated in standard compost or plain tap water within days to weeks, Ting Xu and her colleagues report April 21 in Nature.

      “Biodegradability does not equal compostability,” says Xu, a polymer scientist at the University of California, Berkeley and Lawrence Berkeley National Laboratory. She often finds bits of biodegradable plastic in the compost she picks up for her parents’ garden. Most biodegradable plastics go to landfills, where the conditions aren’t right for them to break down, so they degrade no faster than normal plastics.

      Embedding polymer-chomping enzymes in biodegradable plastic should accelerate decomposition. But that process often inadvertently forms potentially harmful microplastics, which are showing up in ecosystems across the globe (SN: 11/20/20). The enzymes clump together and randomly snip plastics’ molecular chains, leading to an incomplete breakdown. “It’s worse than if you don’t degrade them in the first place,” Xu says.

      Her team added individual enzymes into two biodegradable plastics, including polylactic acid, commonly used in food packaging. They inserted the enzymes along with another ingredient, a degradable additive Xu previously developed, which ensured the enzymes didn’t clump together and didn’t fall apart. The solitary enzymes grabbed the ends of the plastics’ molecular chains and ate as though they were slurping spaghetti, severing every chain link and preventing microplastic formation.

      Filaments of a new plastic material degrade completely (right) when submerged in tap water for several days.Adam Lau/Berkeley Engineering

      Adding enzymes usually makes plastic expensive and compromises its properties. However, Xu’s enzymes make up as little as 0.02 percent of the plastic’s weight, and her plastics are as strong and flexible as one typically used in grocery bags.

      The technology doesn’t work on all plastics because their molecular structures vary, a limitation Xu’s team is working to overcome. She’s filed a patent application for the technology, and a coauthor founded a startup to commercialize it. “We want this to be in every grocery store,” she says. More

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      A new book explores how military funding shaped the science of oceanography

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      Science on a MissionNaomi OreskesUniv. of Chicago, $40

      In 2004, Japanese scientists captured the first underwater images of a live giant squid, a near-mythical, deep-ocean creature whose only interactions with humans had been via fishing nets or beaches where the animals lay dead or dying.

      Getting such a glimpse could have come much sooner. In 1965, marine scientist Frederick Aldrich had proposed studying these behemoths of the abyss using Alvin, a submersible funded by the U.S. Navy and operated by the Woods Hole Oceanographic Institution in Massachusetts. During the Cold War, however, studying sea life was not a top priority for the Navy, the main funder of U.S. marine research. Instead, the Navy urgently needed information about the terrain of its new theater of war and a thorough understanding of the medium through which submarines traveled.

      In Science on a Mission, science historian Naomi Oreskes explores how naval funding revolutionized our understanding of earth and ocean science — especially plate tectonics and deep ocean circulation. She also investigates the repercussions of the military’s influence on what we still don’t know about the ocean.

      The book begins just before World War II, when the influx of military dollars began. Oreskes describes how major science advances germinated and weaves those accounts with deeply researched stories of backstabbing colleagues, attempted coups at oceanographic institutions and daring deep-sea adventures. The story flows into the tumult of the 1970s, when naval funding began to dry up and scientists scrambled to find new backers. Oreskes ends with oceanography’s recent struggles to align its goals not with the military, but with climate science and marine biology.

      Each chapter could stand alone, but the book is best consumed as a web of stories about a group of people (mostly men, Oreskes notes), each of whom played a role in the history of oceanography. Oreskes uses these stories to explore the question of what difference it makes who pays for science. “Many scientists would say none at all,” she writes. She argues otherwise, demonstrating that naval backing led scientists to view the ocean as the Navy did — as a place where men, machines and sound travel. This perspective led oceanographers to ask questions in the context of what the Navy needed to know.

      One example Oreskes threads through the book is bathymetry. With the Navy’s support, scientists discovered seamounts and mapped mid-ocean ridges and trenches in detail. “The Navy did not care why there were ridges and escarpments; it simply needed to know, for navigational and other purposes, where they were,” she writes. But uncovering these features helped scientists move toward the idea that Earth’s outer layer is divided into discrete, moving tectonic plates (SN: 1/16/21, p. 16).

      Through the lens of naval necessity, scientists also learned that deep ocean waters move and mix. That was the only way to explain the thermocline, a zone of rapidly decreasing temperature that separates warm surface waters from the frigid deep ocean, which affected naval sonar. Scientists knew that acoustic transmissions depend on water density, which, in the ocean, depends on temperature and salinity. What scientists discovered was that density differences coupled with Earth’s rotation drive deep ocean currents that take cold water to warm climes and vice versa, which in turn create the thermocline.

      Unquestionably, naval funding illuminated physical aspects of the ocean. Yet many oceanographers failed to recognize that the ocean is also an “abode of life.” The Alvin’s inaugural years in the 1960s focused on salvage, acoustics research and other naval needs until other funding agencies stepped in. That switch facilitated startling discoveries of hydrothermal vents and gardens of life in the pitch black of the deep ocean.

      As dependence on the Navy lessened, many Cold War scientists and their trainees struggled to reorient their research. For instance, their view of the ocean, largely driven by acoustics and ignorant of how sound affects marine life, led to public backlash against studies that could harm sea creatures.

      “Every history of science is a history both of knowledge produced and of ignorance sustained,” Oreskes writes. “The impact of underwater sound on marine life,” she says, “was a domain of ignorance.”

      Buy Science on a Mission from Bookshop.org. Science News is a Bookshop.org affiliate and will earn a commission on purchases made from links in this article. More

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      Wildfires launch microbes into the air. How big of a health risk is that?

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      As climate change brings more wildfires to the western United States, a rare fungal infection has also been on the rise. Valley fever is up more than sixfold in Arizona and California from 1998 to 2018, according to the U.S. Centers for Disease Control and Prevention.

      Valley fever causes coughs, fevers and chest pain and can be deadly. The culprit fungi, members of the genus Coccidioides, thrive in soils in California and the desert Southwest. Firefighters are especially vulnerable to the disease. Wildfires appear to stir up and send the soil-loving fungi into the air, where they can enter people’s lungs.

      If the fires are helping these disease-causing fungi to get around, could they be sending other microorganisms aloft as well? Leda Kobziar, a fire ecologist at the University of Idaho in Moscow, decided in 2015 to see if she could find out if and how microorganisms like bacteria and fungi are transported by wildfire smoke — and what that might mean for human and ecological health.

      By 2018, Kobziar had launched a new research field she named “pyroaerobiology.” First, she asked if microorganisms can even survive the searing heat of a wildfire. The answer, she found, is yes. But how far bacteria and fungi can travel on the wind and in what numbers are two of the many big unknowns.

      With a recent push to spark new collaborations and investigations, Kobziar hopes that scientists will start to understand how important smoke transport of microbes may be.

      For Kobziar’s earliest studies in 2015, her students held up petri dishes on long poles to collect samples of the smoky air near a prescribed fire at the University of Florida experimental forest.L. Kobziar

      Today, Kobziar and colleagues use drones to collect samples at the University of Florida experimental forest.L. Kobziar

      Invisible but pervasive

      Air may look clear, but even in the cleanest air, “hundreds of different bacteria and fungi are blowing around,” says Noah Fierer, a microbiologist at the University of Colorado Boulder.

      Winds whisk bacteria and fungi off all kinds of surfaces — farm fields, deserts, lakes, oceans. Those microbes can rise into the atmosphere to travel the world. Scientists have found microorganisms from the Sahara in the Caribbean, for example.

      Many (if not most) of the airborne microorganisms, including bacteria, fungi and viruses, are not likely to cause disease, Fierer notes. But some can make people sick or cause allergic reactions, he says. Others cause diseases in crops and other plants.

      The billions of tons of dust that blow off of deserts and agricultural fields each year act as a microbial conveyor belt. In places like Arizona, people know to be alert for symptoms of airborne illnesses like Valley fever after dust storms, since infections increase downwind afterward. If dust can move living microorganisms around the globe, it makes sense that particulates in smoke would be microbe movers too, Kobziar says — assuming the microscopic life-forms can survive a fire and a spin in the atmosphere.

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      Tiny travelers

      Rising temperatures and worsening droughts have led to longer and more intense wildfire seasons across the West (SN: 9/26/20, p. 12). Breathing wildfire smoke makes people sick (SN Online: 9/18/20), even causing premature death from heart and lung illnesses. In the United States, wildfire smoke causes about 17,000 premature deaths per year — a number projected to double by 2100, according to a 2018 study in GeoHealth.

      In other parts of the world, the effects are far worse. In 2015, smoke from illegal land-clearing blazes plus wildfires in Indonesia killed an estimated 100,000 people across Southeast Asia, according to a 2016 report in Environmental Research Letters. Blame is usually attributed to particulate matter — organic and inorganic particles suspended in the air, including pollen, ash and pollutants. But scientists and health officials are increasingly realizing that there’s an awful lot we don’t know about what else in smoke is affecting human health.

      The most intense fires, the ones that burn the hottest and release the most energy, can create their own weather systems and send smoke all the way into the stratosphere, which extends about 50 kilometers above Earth’s surface (SN: 9/14/19, p. 12). Once there, smoke can travel around the world just as ash from explosive volcanoes does. Kobziar’s team and others provided compelling evidence in the February ISME Journal that live, viable microorganisms can be carried in smoke plumes — at least near Earth’s surface if not higher up.

      The Fire and Smoke Model Evaluation Experiment, or FASMEE, team set this high-intensity crown fire in the aspens of Fishlake National Forest, Utah, in 2019. The team used a drone to measure microbial concentrations in this smoke.L. Kobziar

      In 2015, while at the University of Florida in Gainesville, Kobziar and her students collected the first air samples for this line of research during a series of planned, or prescribed, burns that Kobziar set at the school’s experimental forest. The group arrived at the forest armed with 3-meter-long poles topped with petri dishes to collect samples from the air.

      Before any fires were set, the team held the petri dishes in the air for three minutes to collect air samples as a pre-fire baseline. Then Kobziar, a certified prescribed burn manager (or as she calls it, a “fire lighter”), lit the fires. Once flames were spreading at a steady rate and smoke was billowing, students hoisted new petri dishes into the smoke, almost as if aiming a marshmallow on a stick at a campfire. This allowed them to collect smoky air samples to compare to the “before” samples.

      Back in the lab, in a dark room held at a constant 23° Celsius, both the baseline and smoky petri dishes — covered and sealed from further contamination — were left for three days. Microbes began to grow. Far more bacterial and fungal species populated the smoky petri dishes than the baseline dishes, indicating that the fire aerosolized some species that weren’t in the air before the fire, Kobziar says.

      These petri dishes show bacterial and fungal colonies that grew after five minutes of exposure to smoke. The smoke came from pine needles collected from Florida then burned in Kobziar’s University of Idaho lab.L. Kobziar

      These petri dishes show bacterial and fungal colonies that grew after five minutes of exposure to smoke. The smoke came from pine needles collected from Florida then burned in Kobziar’s University of Idaho lab.L. Kobziar

      “We were stunned at how many different microbial colonies survived the combustion environment and grew in the smoke samples, compared to very few in the ambient air,” she says. Based on DNA tests, Kobziar’s team identified 10 types of bacteria and fungi; some are pathogenic to plants, one is an ant parasite and one helps plants absorb nutrients. “This was the moment when the way we thought about smoke was completely transformed,” she says.

      In 2017, after Kobziar had moved to Idaho, her team collected soil samples from the University of Idaho’s experimental forest and burned them — this time, in the lab. As smoke unfurled above the burning soils, the researchers collected air samples, and again, sealed them and put them in a dark, warm room to see what would grow. After a week, lots of different microbes, including fungi, had multiplied into colonies on the plates, the researchers reported in 2018 in Ecosphere.

      Alive and on the move

      Since then, Kobziar’s team has collected more air samples during prescribed burns of varying intensities in Florida, Idaho, Montana and Utah, joining forces with the U.S. Forest Service Fire and Smoke Model Evaluation Experiment, or FASMEE, team. For her students’ safety, she’s replaced the poles and petri dishes with drones. She sends a single drone carrying a vacuum pump with a filter into smoke plumes at varying altitudes up to 120 meters, the team described in the journal Fire in 2019.

      [embedded content]
      The FASMEE team set up a mobile research lab on the fire line at Fishlake National Forest. Drone operators sent the machines into the smoke to collect samples, back to the “lab” to return samples, then back up to collect more multiple times. They found about 1,000 different microbe types in the smoke.

      In every experiment, the researchers have found living bacteria and fungi, many of which were not found in any of the air samples taken before the fires. In Utah smoke samples, for example, the FASMEE team found more than 100 different fungi that were not in the air before the fire, Kobziar says. Findings included species of Aspergillus, which can cause fevers, coughs and chest pain, as well as Cladosporium, molds that can cause allergies and asthma.

      Whether any of these microorganisms pose a danger to people is unknown, Kobziar cautions. Her team has not tested whether the microbial species that survive the heat can cause disease, but the group plans to do so.

      The research in Utah revealed another crucial fact: These microbes are tough. Even in smoke from high-intensity, high-temperature fires, about 60 percent of bacterial and fungal cells are alive, Kobziar says. Roughly 80 percent seem to survive lower-intensity fires, which is “about the same percentage of cells we’d expect to see alive in ambient air conditions,” she says. Thus, these first studies show that fires are sending live bacteria and fungi into the air. And that they can travel at least 120 meters above the ground and close to a kilometer from a flame front.

      But many basic questions remain, Kobziar says. How do the microbes change — in quantity, type or viability — based on distance traveled away from the flames? How far can they actually go? How do different fuel sources — pine trees, grasslands, deciduous trees or crops, for example — affect microbial release? How does fire intensity affect what is released and how far it travels? Does the type of combustion — smoldering (like a wet log on a campfire) versus high-intensity flaming fires — affect what is released? How does temperature or humidity or weather affect microbial survival?

      Then, of course, Kobziar has plenty of questions about how to conduct this new field of research: What are the safest and best ways to sample the air in the dangerous environment of an unpredictable wildfire? How do you avoid contaminating the biological samples?

      She’s been learning as she goes, honing her methodology. The answers to many of those questions could come if one of Kobziar’s dream collaborations comes true: She wants to work with the researchers whose studies involve the NASA DC-8 “flying laboratory,” which explores Earth’s surface and atmosphere for studies ranging from archaeology to volcanology.

      Researchers have already tracked many different chemicals released by fires into the stratosphere from the Arctic to the South Pacific and everywhere in between, using the DC-8 for NASA’s Atmospheric Tomography Mission, says Christine Wiedinmyer, a fire emissions modeler at the Cooperative Institute for Research in Environmental Sciences in Boulder, Colo. Finding traceable signatures of fires everywhere in the atmosphere suggests that fires could also be sending bacteria and fungi around the world, she says.

      Nine kilometers above Earth’s surface, a camera on NASA’s DC-8 flying laboratory took this image of thunderclouds rising above columns of smoke from a fire in eastern Washington on August 8, 2019. Such storms, formed by intense fires, loft particulate matter, chemicals and maybe even microbes into the stratosphere.David Peterson/U.S. Naval Research Lab

      “Pyroaerobiology is so cool,” says Wiedinmyer, who tracks and simulates the movement of chemicals in wildfire smoke around the world. She sees no reason that such atmospheric chemistry models couldn’t also be used for tracking and forecasting the movement of microbes in smoke plumes — once researchers collect sufficient measurements. Those data might answer basic questions about the human health hazards of microorganisms in smoke.

      Microbiologist Fierer in Boulder and Wiedinmyer have collaborated on chemistry sampling and modeling. The two plan to move to bacterial and fungal modeling using data Fierer is gathering on microbial concentrations in wildfire smoke.

      Kobziar, meanwhile, is working with atmospheric modelers to figure out how to model microbes’ movements in smoke. The long-term aim is to develop models to supplement current air-quality forecasts with warnings of air-quality issues across the United States related to wildfire-released microorganisms in smoke.

      A U.S. map

      While Kobziar’s team focuses on measuring microbes in smoke, Fierer’s team is working to get a baseline of what microbes are in the air at different locations during normal times and then comparing the baseline to smoke. The group has been sampling indoor and outdoor air at hundreds of U.S. homes to “map out what microbes we’re breathing in as we’re walking around doing our daily business,” Fierer says. They are also sampling air across Colorado, which experienced record-breaking fires in 2020 (SN: 12/19/20 & 1/2/21, p. 32).

      Fierer’s team uses sampling stations with small, high-powered vacuums atop 2-meter-high poles to “sample air for a period of time without smoke. Then boom, smoke hits [the site], we sample for a few days when there’s smoke in the air, and then we also sample afterward,” Fierer says. Analyzing samples from before, during and after a fire is ideal, he says, as there’s tremendous variation in microbial and fungal populations in the air. Near a Midwestern city in winter, for example, microorganisms might include ones associated with local trees or, strangely, dog feces; near a Colorado cattle feedlot in summer, microbes might include those associated with cattle feces.

      Joanne Emerson, then a postdoctoral researcher at the University of Colorado Boulder, samples air atop a 300-meter-tall tower at the Boulder Atmospheric Observatory.N. Fierer

      When the team gets its results — data collection and analysis have been delayed by the pandemic — Fierer says, “we will know the amounts and types of microbes found in wildfire smoke compared with paired smoke-free air samples, and whether those microbes are viable.” At least in Colorado. Once scientists get the measurements of how many microbes can be carried in smoke, and to what altitudes, Fierer’s group can combine that information with global smoke production numbers to come up with “some back-of-the-envelope calculations” of the volume of microbes traveling in smoke plumes. Eventually, he says, scientists could figure out how many are alive, and whether that even matters for human health — still “an outstanding question.”

      Big leaps forward could be made if more scientists get involved in the research, Fierer and Kobziar both say. This research needs a truly multidisciplinary approach, with microbiologists, forest ecologists and atmospheric scientists collaborating, Fierer says. Going it alone would “be equivalent to a microbiologist studying microbes in the ocean and not knowing anything about oceanography,” he says. Fortunately, after Kobziar and infectious disease physician George Thompson of the University of California, Davis published a call-to-arms paper in Science last December, summing up their pyroaerobiology research and noting key questions, several researchers from different fields expressed interest in investigating the topic. “That’s exactly what we hoped would happen,” Kobziar says.

      Is there danger?

      In recent years, Thompson has seen a substantial increase in patients getting Valley fever and other fungal infections after nearby wildfires. He was well aware that when particulate matter in smoke gets into the lungs, it can cause breathing difficulties, pneumonia and even heart attacks. In fact, scientists reported in the Journal of the American Heart Association in April 2020 that exposure to heavy smoke during 2015–2017 wildfires in California raised the risk of heart attacks by up to 70 percent.

      He began to wonder if California’s record-breaking infernos were stirring up other microbes along with the fungus that causes Valley fever. So he joined forces with Kobziar.

      The Valley fever link appears to be real, but so far, local. For example, after the 2003 Simi Fire burned through Ventura County, more than 70 people got sick with Valley fever. But whether the Coccidioides fungi can travel to make people sick at a distance from the fire, no one knows.

      There are ways to figure out if more people, either locally or farther away, are getting sick with bacterial or fungal infections after wildfires. One way, Thompson says, is to look at a community’s antibiotic prescriptions and hospitalizations in the month preceding and the month after a fire: More prescriptions or hospitalizations from bacterial or fungal infections after a fire could indicate a link.

      In 2019 at the American Transplant Congress meeting, for example, researchers linked California wildfires with increased hospitalizations related to Aspergillus mold and Coccidioides fungi infections.

      But until we know more about what microbes fires release and where they go, we won’t know how important such a link is for human health, Fierer says.

      There’s so much we don’t know yet, Thompson agrees. “We still have a lot of work to do. This is sort of the beginning of the beginning of the story.” More

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      Discarded COVID-19 PPE such as masks can be deadly to wildlife

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      A Magellanic penguin in Brazil ingested a face mask. A hedgehog in England got itself entangled in a glove. An octopus off the coast of France was found seeking refuge under a mask.

      Wildlife and ecosystems around the world are suffering from the impact of discarded single-use COVID-19 protective gear, researchers warn March 22 in Animal Biology. Latex gloves and polypropylene masks which protect people from the coronavirus are exacerbating the plastic pollution problem when not disposed of properly and are causing wildlife deaths (SN:11/20/20). The study is the first global documentation of the impacts of COVID-19 litter on wildlife via entanglement, entrapment and ingestion (SN:12/15/20).

      In August 2020, volunteers cleaning canals in Leiden, Netherlands, chanced upon a perch — a type of freshwater fish — trapped inside a finger of a latex glove. The ensnared fish was the first recorded wildlife casualty caused by COVID-19 litter in the Netherlands. The find shocked two Leiden-based biologists — Auke-Florian Hiemstra and Liselotte Rambonnet — who wanted to know more about the extent of COVID-19 litter’s impact on wildlife. They embarked on an extensive search, online and in newspapers, to collate examples.

      A perch found trapped in a latex glove (pictured) in a Leiden canal inspired two Dutch biologists to look into how discarded single-use PPE is impacting animals around the world.Auke-Florian Hiemstra

      They found 28 such instances from all around the world, pointing to a larger, global problem.   The earliest reported victim was from April 2020: an American robin in Canada, which appears to have died after getting entangled in a face mask. Pets are at risk, too: In Philadelphia, a domestic cat ingested a glove, and a pet dog in Boston that had consumed a face mask. “Animals with plastic in their stomach could starve to death,” says Rambonnet, of Leiden University.

      “What this paper does is give us insight to the extent of the [COVID-19] litter’s impact on wildlife, so we can make efforts to minimize the consequences,” says Anna Schwarz, a sustainable plastics researcher at TNO, an independent organization for applied scientific research in Utrecht, Netherlands. That could be a tall order: A report published by Hong Kong–based marine conservation organization OceansAsia, for instance, estimates that 1.56 billion face masks would have entered the world’s ocean last year, part of the 8 million to 12 million metric tons of plastic that reaches the oceans annually.

      As the far-reaching impacts of COVID-19 litter on wildlife become more apparent over time, Hiemstra, of the Naturalis Biodiversity Center, and Rambonnet are relying on citizen scientists to help them continue monitoring the situation: At www.covidlitter.com, people from around the world can submit their observations of affected wildlife. To curb the growing hazards, the study authors recommend switching to reusables wherever possible, as well as cutting up disposal gloves and snipping the straps off of single-use masks to prevent animals from getting entangled or trapped in them.

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      “The paper highlights the importance of proper waste management, especially the recycling or disposal of single-use materials,” says Schwarz.

      But the situation isn’t always so dire. Some animals have commandeered discarded PPE for their own uses. COVID-19 litter has become so pervasive that birds have been observed using face masks and gloves as building materials for their nests. “Bird nests from 2020 are so easy to recognize,” says Hiemstra. More

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      Corals’ hidden genetic diversity corresponds to distinct lifestyles

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      Stony corals that build reefs have been hiding their diversity in plain sight. A genetic analysis of the most widespread reef coral in the Indo-Pacific revealed that rather than being a single species (Pachyseris speciosa), it was actually four distinct species of coral, researchers report April 2 in Current Biology.

      Coral reefs are the condominiums of ocean biodiversity, supporting more species per square meter than any other marine habitat. Understanding which coral species foster that biodiversity and how those corals behave is vital to taking care of them, especially as a warming climate threatens overall ocean biodiversity (SN: 5/6/20). “Just knowing what’s there is critical to tracking what we are losing,” says Rebecca Vega-Thurber, a marine microbiologist at Oregon State University in Corvallis, who was not involved in the new study. The results suggest other corals thought to be a single species may actually be much more diverse than researchers realized.

      Using a combination of scuba gear and remotely operated vehicles, marine biologist Pim Bongaerts of the California Academy of Sciences in San Francisco and colleagues sampled more than 1,400 P. speciosa corals from the ocean surface down to 80 meters. In the lab, the sampleslooked identical, and their internal structures were indistinguishable in scanning electron microscope images. Yet, their genomes — their full genetic instruction books — revealed the corals had diverged millions of years ago. That made sense for one of the species in the Red Sea’s Gulf of Aqaba, which was geographically separated from the others. But the other three newly identified species lived together on the same reefs in the waters off South Asia. If the corals were living together, why didn’t one overtake the other two, the team wondered.

      Examining habitat data from their dives, the researchers found the three distinct coral species favored different water depths, with one abundant in the top 10 meters and the other two flourishing deeper down. The three coral species also had different concentrations of photosynthetic algae and pigments, suggesting they had distinct strategies for hosting their algae partners that provide food. And spawning times of these three species were slightly spread out too. One released most of its gametes five days after the full moon, another seven days after, and the third at nine days and counting. The separation of spawning could help the eggs and sperm of each species hook up with its correct species match.

      Marine biologists Pim Bongaerts and Norbert Englebert collect coral samples during a dive at Holmes Reef in the Coral Sea north of Australia.David Whillas

      This study is the first to show how a set of cryptic reef corals are splitting up their shared ecological space — by depth, physiology and spawning time, Bongaerts says. “There are all these cryptic lineages occurring, but they’ve largely been ignored from an ecological point of view.”

      The results open the door to the possibility that many other doppelgänger corals may be multiple species that coexist thanks to ecological differences, says reef genomicist Christian Voolstra at the University of Konstanz in Germany. “There is a minimal chance that they picked the unicorn, but I highly doubt it. This paper shows that in all likelihood there is a huge diversity of reef corals with distinct ecologies.” More

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      A trek under Thwaites Glacier’s ice shelf reveals specific risks of warm water

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      The under-ice trek of an autonomous underwater vehicle is giving scientists their first direct evidence for how and where warm ocean waters are threatening the stability of Antarctica’s vulnerable Thwaites Glacier. These new data will ultimately help scientists more accurately project the fate of the glacier — how quickly it is melting and retreating inland, and how far it might be from complete collapse, the team reports April 9 in Science Advances.

      “We know there’s a sick patient out there, and it’s not able to tell us where it hurts,” says Eric Rignot, a glaciologist at the University of California, Irvine who was not involved in the new study. “So this is the first diagnosis.”

      Scientists have eyed the Florida-sized Thwaites Glacier with mounting concern for two decades. Satellite images reveal it has been retreating at an alarming rate of somewhere between 0.6 to 0.8 kilometers per year on average since 2001, prompting some to dub it the “doomsday glacier.” But estimates of how quickly the glacier is retreating, based on computer simulations, vary widely from place to place on the glacier, Rignot and other researchers reported in Science Advances in 2019. Such uncertainty is the biggest difficulty when it comes to future projections of sea level rise (SN: 1/7/20).

      The primary culprit for the rapid retreat of Thwaites and other Antarctic glaciers is known: Relatively warm ocean waters sneak beneath the floating ice shelves, the fringes of the glaciers that jut out into the ocean (SN: 9/9/20). This water eats away at the ice shelves’ underpinnings, points where the ice is anchored to the seafloor that buttress the rest of the glacier against sliding into the sea.

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      Scientists have used satellite data to roughly map out what lies beneath the Thwaites ice shelf. Three deep channels carved into the seafloor snake beneath a vast water-filled cavity 120 kilometers across. But without direct measurements of the chemistry and paths the water takes to reach Thwaites’ underbelly, it’s been impossible to know where the threatening water is really coming from, how warm it is, and where it’s attacking the ice, says Anna Wåhlin, a physical oceanographer at the University of Gothenburg in Sweden.

      In February and March 2019, Wåhlin and her colleagues sent the AUV Ran to traverse two of the deep channels. Gliding about 50 meters above the seafloor, the AUV collected the first direct measurements of temperature, salinity and oxygen levels in the water. From those measurements, the team was able to trace the origins of different parcels of water mixing beneath Thwaites.

      Based on its chemical makeup, some of the warm water came from neighboring Pine Island Bay. “We were very surprised,” because Pine Island Bay wasn’t previously thought to be a major player in the future of Thwaites, Wåhlin says. The water mass from there was near the bottom of the cavity, about 500 meters deep, and was both less salty than the surrounding seawater and several degrees Celsius warmer than the freezing point. That’s an unstable situation, likely to create turbulence, and increasing the potential for erosion of the ice, Wåhlin says.

      The find also suggests that what happens in Pine Island Bay doesn’t necessarily stay in Pine Island Bay — and that the fate of Thwaites may be closely intertwined with that of the Pine Island Glacier, another rapidly-melting river of ice, Wåhlin says. Together, the two glaciers are responsible for most of the ice and water that Antarctica is currently shedding. But while Thwaites is still pinned to the seafloor in some places, which slows its slide into the sea, those underpinnings are long gone for Pine Island, she says.

      In April, scientists identified three tipping points for the precarious Pine Island glacier, thresholds it might cross as climate conditions evolve that would lead to phases of rapid, irreversible retreat. The third and final threshold, prompted by a roughly 1.2 degree Celsius increase in the temperature of ocean waters compared with current ocean temperatures, would drive the glacier to complete collapse, the team found.

      An upcoming expedition Wåhlin and others are planning for January 2022 will use two AUVs to explore much farther into the cavity beneath Thwaites. Ideally, the AUVS will get several hundred kilometers closer to the shore, all the way to the grounding line, where the base of the glacier rests on land.

      “That’s the key down the line,” Rignot says. Observing how water masses are interacting with the glacier’s grounding line will be crucial to understanding the future of the glacier, he says. “That’s the place where melting makes the most difference to the glacier’s stability.”

      And there’s a lot that researchers still don’t know about the vast water cavity beneath Thwaites ice shelf, including its precise dimensions and the best places for AUVs to explore, he adds. “We are only just at the beginning.” More

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      A spike in Arctic lightning strikes may be linked to climate change

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      Climate change may be sparking more lightning in the Arctic.

      Data from a worldwide network of lightning sensors suggest that the frequency of lightning strikes in the region has shot up over the last decade, researchers report online March 22 in Geophysical Research Letters. That may be because the Arctic, historically too cold to fuel many thunderstorms, is heating up twice as fast as the rest of the world (SN: 8/2/19).

      The new analysis used observations from the World Wide Lightning Location Network, which has sensors across the globe that detect radio waves emitted by lightning bolts. Researchers tallied lightning strikes in the Arctic during the stormiest months of June, July and August from 2010 to 2020. The team counted everywhere above 65° N latitude, which cuts through the middle of Alaska, as the Arctic.

      The number of lightning strikes that the detection network precisely located in the Arctic spiked from about 35,000 in 2010 to about 240,000 in 2020. Part of that uptick in detections may have resulted from the sensor network expanding from about 40 stations to more than 60 stations over the decade.

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      And just looking at the 2010 and 2020 values alone may overstate the increase in lightning, because “there’s such variability, year to year,” and 2020 was a particularly stormy year, says Robert Holzworth, an atmospheric and space scientist at the University of Washington in Seattle. In estimating the increase in average annual lightning strikes, “I would argue that we have really good evidence that the number of strokes in the Arctic has increased by, say, 300 percent,” Holzworth says.

      That increase happened while global summertime temperatures rose from about 0.7 degrees Celsius above the 20th century average to about 0.9 degrees C above — hinting that global warming may create more favorable conditions for lightning in the Arctic.

      It makes sense that a warmer climate could generate more lightning in historically colder climes, says Sander Veraverbeke, an earth systems scientist at VU University Amsterdam who was not involved in the work. If it does, that could potentially ignite more wildfires (SN: 4/11/19). But the apparent trend in Arctic lightning strikes should be taken with a grain of salt because it covers such a short period of time and the detection network includes few observing stations at high latitudes, Veraverbeke says. “We need more stations in the high north to really accurately monitor the lightning there.” More

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      Dazzling underwater photos capture new views and scientific detail of fish larvae

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      The open ocean is a veritable soup of tiny critters, including newborn fishes. It’s hard to learn about them, though, because they are mere millimeters long and semitransparent. When netted from research vessels, their delicate body parts may get mashed or removed. Now, a partnership between scientists and scuba divers is giving researchers fresh perspectives on the secrets of larval fishes.

      Underwater photos taken at night — when larval fishes migrate to within 200 meters of the ocean surface — reveal colors, body structures and behaviors that could never be seen in preserved specimens. Examining those same fishes back in the lab lets ichthyologists match the photographed larval fishes to known species, researchers report March 30 in Ichthyology & Herpetology.

      Scientists at the Smithsonian Institution and the National Oceanic and Atmospheric Administration hatched a collaboration in 2016 with blackwater divers — who enter the ocean in the dark of night — to photograph larval fishes and collect them as specimens. With lights in hand, divers Jeff Milisen and Sarah Mayte snapped up-close photos of nearly 80 larval fishes, then gingerly captured and shipped them to scientists to be studied alongside their mugshots.

      “Fish larvae that looked utterly drab as specimens have turned out to have brilliantly colored markings and fantastic structures,” says Ai Nonaka, a larval fish expert at the Smithsonian’s National Museum of Natural History in Washington, D.C.

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      Fragile appendages

      Specialists like Nonaka sort out larval fish identities by looking at body shapes and minuscule features through microscopes and by analyzing DNA of larval tissue. Unlike their swimming parents, fish larvae drift on currents, and their strange body parts — adaptations for a drifting lifestyle — make larvae look nothing like adults. 

      “Larval fishes are extremely difficult to identify,” says Dave Johnson, an ichthyologist also at the Smithsonian. Scientists have mistakenly given larval fishes new scientific names, not recognizing them as early life stages of known species.

      Because larval fishes are soft and fragile, they don’t travel well. Larvae lose fins and other delicate structures that evoke their behavior. The scalloped ribbonfish (Zu cristatus) larva, for example, has spaghetti-like ornamental fins sprinkled with white spots that get broken off on specimens. The way these ornamental structures appear to flow out like tentacles in the images of wild larvae suggests the larvae could be jellyfish mimics, say the study authors.

      Scalloped ribbonfish (Zu cristatus) larva in the oceanJ. Milisen

      Scalloped ribbonfish (Z. cristatus) larva specimenA. Nonaka/Smithsonian NMNH

      The trailing guts of a barbeled dragonfish (Aristostomias sp.) larva get mashed or broken off altogether, but the undersea photo reveals it coiled up into a tight corkscrew. Nonaka and Johnson confess that scientists don’t yet understand the function of the trailing guts seen in some larval fishes. One theory is that exposed innards might somehow increase digestion efficiency, while another suggests they could confuse predators.

      Barbeled dragonfish (Aristostomias sp.) larva in the oceanJ. Milisen

      Barbeled dragonfish (Aristostomias sp.) larva specimenA. Nonaka/Smithsonian NMNH

      Hidden colors

      Ethanol preservation of specimens repels bacteria and fungi, but leaches out colors. The three-spot righteye flounder (Samariscus triocellatus) larva, bone white as a specimen, is bright blue. Its dorsal and anal fins are fringed with white, and rows of yellow spots dot the base of the fin rays. While their function has yet to be studied, it’s possible that these borders create a flickering visual effect to help the fish escape from predators, suggests Geoff Moser, a retired NOAA fisheries biologist not involved with the study. Called “flicker fusion,” it’s been examined in other animals such as striped snakes as a form of camouflage on the go.

      Three-spot righteye flounder (Samariscus triocellatus) larva in the oceanJ. Milisen

      Three-spot righteye flounder (S. triocellatus) larva specimenA. Nonaka/Smithsonian NMNH

      The deep-sea tripodfish (Bathymicrops sp.) is plain and pale when prepared as a specimen and uniform brown as an adult fish — not exactly a looker. But the larva appears to have donned a clown costume with large white and orange polka dots flecked on its otherwise blue-hued body. In an ethanol specimen, its pectoral fins look soft and ghostly, whereas the living larva sports flamboyant, spiky and spotted fins. The function of the coloration is unknown. says Nonaka, but it could also be a flicker fusion trick.

      Deep-sea tripodfish (Bathymicrops sp.) larva in the oceanJ. Milisen

      Deep-sea tripodfish (Bathymicrops sp.) larva specimenA. Nonaka/Smithsonian NMNH

      Fishy behavior

      In larval specimens, scientists can observe some structures as evidence of behaviors. But undersea observations of wild larval fishes can show what they’re really up to when they are alive. The larva of the barred conger (Ariosoma fasciatum) is super flat, quite unlike the cylindrical adult. Yet a photo shows that it swims like an adult barred conger, by undulating its long body laterally. So, while it’s more svelte as a larva, it’s got some of the adult movements down.

      Barred conger (Ariosoma fasciatum) larva in the oceanJ. Milisen

      Barred conger (A. fasciatum) larva specimenA. Nonaka/Smithsonian NMNH

      Undersea observations can also reveal associations larvae have with other marine animals, including other tiny critters that also ride the currents. For example, a petite Pacific pomfret (Brama japonica) larva was caught on camera riding on a jellyfish. That’s a discovery that the study authors were unwilling to even speculate about. Although larval fishes have been seen taking shelter in the tentacles of jellies, hitching a ride on top of a jellyfish seems like an odd twist on that behavior.

      A pacific pomfret (Brama japonica) larva (pictured from three angles) in the ocean, riding a jellyfishJ. Milisen (photos); E. Otwell/Science News (collage)

      Pacific pomfret (Brama japonica) larva specimenA. Nonaka/Smithsonian NMNH

      Each larval fish that gets identified by scientists sets the stage for conservation. By knowing where larval fishes of particular species live, researchers can better advise on how to manage the ocean ecosystems the fishes depend on for survival.

      Conservation planning also requires knowledge of behavior (SN: 12/30/10). So photographing larval fishes and making their specimens available for identification means researchers get a handle on fishes’ behavioral adaptations for survival in the wild.

      “I’ve been working with fish larvae for over 40 years,” says Moser. “The chance to see these larvae in their environment was a wonderful advance in our scientific endeavors.” More