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    Fake fog, ‘re-skinning’ and ‘sea-weeding’ could help coral reefs survive

    Erinn Muller should have reason to despair. The marine biologist studies coral health in Florida, a state whose reefs have been devastated by extreme heat, increasingly ferocious hurricanes and deadly infectious diseases (SN: 6/15/23; SN: 9/13/23; SN: 7/9/19).

    “We’ve lost 98 percent of our living coral cover,” says Muller, of the Mote Marine Laboratory in Sarasota, Fla. While among the hardest hit, Florida isn’t alone. From Australia’s Great Barrier Reef to the Caribbean, coral reefs globally are in trouble.

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    But innovative efforts to protect and restore coral reefs buoy Muller’s hopes. She just has to visit Mote’s Caribbean king crab nursery, a project of reef restoration expert Jason Spadaro. There, tiny specks of crustaceans will grow into salad-loving foragers. Once they are set loose on nearby reefs, Maguimithrax spinosissimus eat away suffocating seaweed.

    “I’m optimistic because there is really truly so much work being done” to restore coral reefs, says Tali Vardi, a marine biologist and executive director of the Coral Restoration Consortium, a global community of scientists, managers and restoration experts dedicated to helping coral reefs. While safeguarding the future of coral reefs ultimately depends on halting climate change, “we’re trying to maintain pockets of biodiversity” that can serve as a springboard for the long-term recovery of reefs.

    Given how diverse coral reefs are, Vardi says, researchers need a diversity of solutions to match. “There’s no silver bullet here.”

    Around the globe, coral biologists are trying everything from low-tech seaweed removal to high-tech artificial fog production to protect corals. Here’s a closer look at three projects that researchers are developing to help save coral reefs.

    Sea-weeding, literally

    In Australia’s Great Barrier Reef, it’s not crabs doing the weeding. It’s volunteers with Earthwatch Institute — an international environmental organization — snorkeling and diving underwater to pluck macroalgae, the weed of the sea. The volunteers’ goal is to free parts of the reef from a seaweed scourge to see if that leads to a resurgence in coral.

    “There’s been this issue with increases in macroalgae versus corals for a long time,” says David Bourne. “If something’s out of whack” with the reef ecosystem, “the corals lose out and the macroalgae take over.”

    Though they seem like a cross between plants and rocks, the hard corals that form reefs are actually giant colonies of tiny animals called coral polyps. The polyps secrete a hard skeleton made of calcium carbonate, and skeleton by skeleton, they build an undersea city. Tiny photosynthetic algae partners living inside the polyps give the corals their brilliant colors and generate energy for their hosts.

    Seaweed, however, takes up space and soaks up light that could otherwise be used by corals. If corals decline in number due to stressors like heat or disease, seaweed can quickly proliferate and take their place.

    Bourne, a marine biologist at James Cook University in Townsville, Australia, wanted to know if the seaweed-removal program being run by Earthwatch was effective. From 2018 to 2021, volunteers pruned seaweed from 24 sections of the reef — each 5 meters by 5 meters — several times per year, while leaving other seaweed-laden areas alone. In total, they removed a whopping 2,148 kilograms of seaweed.

    At the start, the tended plots had enough corals to cover only about 34 square meters. Removing macroalgae from those plots led to a total gain of nearly 203 square meters of coral cover, enough to blanket a tennis court, Bourne’s team reported September 13 in the Journal of Applied Ecology. This change wasn’t seen in the plots left unpruned.

    After volunteers removed suffocating seaweed from sections of Australia’s Great Barrier Reef, coral cover expanded dramatically in just a few years. These photos show the same part of the reef in May 2019 and May 2023.Hillary Smith

    “It’s not surprising that we saw some recovery,” Bourne says. “What was surprising was the amount of recovery and how quickly it happened.” Sea-weeding is a straightforward way to skew the reef’s competitive balance and help corals thrive, he says.

    Bourne hopes the simplicity of the approach will help it spread. “The advantage of sea-weeding is it’s really low tech; anybody can do it,” he says. Plus, seaweed tends to be an issue on reefs that are close to shore and known to local communities, “so there’s active groups that are interested in helping.”

    ‘Re-skinning’ a coral skeleton

    Though it may sound macabre, the calcium carbonate skeletons of dead reefs can serve as vital scaffolding for new corals to flourish. “Re-skinning” a dead reef takes advantage of coral microfragments, small bits of coral polyps. Growing microfragments in the lab and then transplanting them onto reef skeletons can, in a way, bring a dead ecosystem back to life.

    David Vaughan discovered the restorative potential of coral microfragments through what he calls a “eureka mistake.” Vaughan, formerly executive director of Mote and now head of the nonprofit Plant A Million Corals in Summerland Key, Fla., accidentally broke off shards of a branching coral while moving it to a new tank. Some coral polyps remained on the bottom of the tank. Vaughn assumed the tiny animals wouldn’t survive. But when he checked on them about two weeks later, he saw instead that they had quickly grown and multiplied.

    Large corals grow slowly, Muller says, because they have to put a lot of energy into creating more of their calcium carbonate skeleton. If you instead affix multiple microfragments, consisting of a thin skeletal layer with a small bit of live coral tissue on top, near each other on a hard surface, they grow rapidly and fuse together. Mote scientists “hacked the biology of a lot of these slow-growing species to encourage them to put a lot of their resources into creating tissue faster,” Muller says.

    Microfragments of slow-growing corals that are placed near each other on the skeleton of a dead coral will quickly grow and merge together. Coral fragments, like these pictured at Mote Marine Laboratory, can be grown in land-based nurseries.Mote Marine Laboratory

    A 2018 study found that microfragments of the mountainous star coral (Orbicella faveolata) grew 10 times as much tissue over a 31-month period as the normal, larger fragments that were previously used for reef restoration. For every square centimeter of coral that was planted at the beginning of the experiment, microfragments grew an average of 3.38 square centimeters of new tissue, while larger fragments grew only 0.35 square centimeters. Ocean plantings of coral microfragments have since withstood disease, bleaching and hurricanes, and grown large enough to reproduce within several years.

    “Spawning after five years,” Spadaro says, “was definitely a game changer in terms of restoration.” Re-skinning with microfragments can give you functional reef ecosystems in a fraction of the time as previous methods. Mote scientists have since shared their knowledge with others working to restore corals around the world, such as in Hawaii and the Caribbean.

    Making shade

    Bleaching is the dramatic outcome of great hardship; pushed to the brink by extreme stress, a strained coral belches out its symbiotic photosynthetic algae, turning stark white and losing its primary food source. Excessive heat is the most common culprit, but it’s not the only one.

    Excess light can lead to bleaching, too, says Peter Butcherine, a biologist at Southern Cross University in Coffs Harbour, Australia. Too much light during photosynthesis, performed by the corals’ algae partners, leads to an abundance of toxic oxygen-containing molecules that are highly reactive and can cause cell death. Protecting corals from too much sun exposure can help prevent bleaching, but “you can’t roll out thousands of square meters of shade cloth” to shield an area the size of the Great Barrier Reef, Butcherine says.

    Instead, Butcherine and others have turned to a more ephemeral approach: creating fog. “It’s essentially a sea mist,” Butcherine says. Though misting the entire Great Barrier Reef isn’t feasible, marine fog could be used to protect sensitive parts of the reef during the time of day when sunlight is at its harshest.

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    Too much sunlight can lead to coral bleaching, much like excessive heat can. By creating artificial marine fog using arrays of misters mounted to ships, like what’s seen in this video, researchers hope to shield reefs such as Australia’s Great Barrier Reef from harmful rays.

    Butcherine and colleagues showed that shading corals for just four hours a day can delay bleaching even when water temperatures are high, such that corals could withstand three extra weeks of bleaching-level heat. The results of that laboratory study were published in the Sept. 20 Frontiers in Marine Science. This delay could help corals hold on to their algal partners until the environment around them cools.

    Because it’s still being developed, marine fogging is quite expensive; it requires large arrays of misters mounted to ships. But Butcherine is excited by the potential of using solar power, including sun-powered drones mounted with misters, to implement the technique at a wider scale, and even at other reefs around the world.

     “I’m optimistic that we can make a difference,” Butcherine says. More

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    AI can alert urban planners and policymakers to cities’ decay

    More than two-thirds of the world’s population is expected to live in cities by 2050, according to the United Nations. As urbanization advances around the globe, researchers at the University of Notre Dame and Stanford University said the quality of the urban physical environment will become increasingly critical to human well-being and to sustainable development initiatives.
    However, measuring and tracking the quality of an urban environment, its evolution and its spatial disparities is difficult due to the amount of on-the-ground data needed to capture these patterns. To address the issue, Yong Suk Lee, assistant professor of technology, economy and global affairs in the Keough School of Global Affairs at the University of Notre Dame, and Andrea Vallebueno from Stanford University used machine learning to develop a scalable method to measure urban decay at a spatially granular level over time.
    Their findings were recently published in Scientific Reports.
    “As the world urbanizes, urban planners and policymakers need to make sure urban design and policies adequately address critical issues such as infrastructure and transportation improvements, poverty and the health and safety of urbanites, as well as the increasing inequality within and across cities,” Lee said. “Using machine learning to recognize patterns of neighborhood development and urban inequality, we can help urban planners and policymakers better understand the deterioration of urban space and its importance in future planning.”
    Traditionally, the measurement of urban quality and quality of life in urban spaces has used sociodemographic and economic characteristics such as crime rates and income levels, survey data of urbanites’ perception and valued attributes of the urban environment, or image datasets describing the urban space and its socioeconomic qualities. The growing availability of street view images presents new prospects in identifying urban features, Lee said, but the reliability and consistency of these methods across different locations and time remains largely unexplored.
    In their study, Lee and Vallebueno used the YOLOv5 model (a form of artificial intelligence that can detect objects) to detect eight object classes that indicate urban decay or contribute to an unsightly urban space — things like potholes, graffiti, garbage, tents, barred or broken windows, discolored or dilapidated façades, weeds and utility markings. They focused on three cities: San Francisco, Mexico City and South Bend, Indiana. They chose neighborhoods in these cities based on factors including urban diversity, stages of urban decay and the authors’ familiarity with the cities.
    Using comparative data, they evaluated their method in three contexts: homelessness in the Tenderloin District of San Francisco between 2009 and 2021, a set of small-scale housing projects carried out in 2017 through 2019 in a subset of Mexico City neighborhoods, and the western neighborhoods of South Bend in the 2011 through 2019 period — a part of the city that had been declining for decades but also saw urban revival initiatives. More

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    Novel device promotes efficient, real-time and secure wireless access

    A new device from the lab of Dinesh Bharadia, an affiliate of the UC San Diego Qualcomm Institute (QI) and faculty member with the Jacobs School of Engineering’s Department of Electrical and Computer Engineering, offers a fresh tool for the challenge of increasing public access to the wireless network.
    Researchers developed prototype technology to filter out interference from other radio signals while sweeping underutilized spectrum frequency bands for high-traffic periods. The technology could help regulators distribute wireless access at an affordable cost during low-traffic periods.
    “Through meticulous analysis of spectrum usage, we can identify underutilized segments and hidden opportunities, which, when leveraged, would lead to a cost-effective connectivity solution for users around the globe,” said Bharadia. “Crescendo stands at the forefront of this initiative, offering a low-complexity yet highly effective solution with advanced algorithms that provides robust spectrum insights for all.”
    Accessing a “Quiet” Resource
    When unoccupied, broadband frequencies owned by users like the U.S. Navy or military can offer wireless connection to the public or corporations at low cost. The challenge is determining when the primary owners use the frequencies, and when they would be available for public use.
    Working with Associate Professor Aaron Schulman of the Jacobs School of Engineering Computer Science and Engineering Department, researchers from Bharadia’s Wireless Communications, Sensing and Networking Group created a novel device called “Crescendo.”
    Crescendo features adaptive software that allows it to sweep for activity across a range of frequencies within an agency-owned wideband spectrum. The device can adapt to signal interference in real-time by dynamically adjusting which signals it receives to tune out interference from nearby towers, base stations and other sources of high power signals. The technology’s high signal fidelity also ensures that users can count on a secure connection, with any cyberattacks identified in real-time. More

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    Robot stand-in mimics movements in VR

    Researchers from Cornell and Brown University have developed a souped-up telepresence robot that responds automatically and in real-time to a remote user’s movements and gestures made in virtual reality.
    The robotic system, called VRoxy, allows a remote user in a small space, like an office, to collaborate via VR with teammates in a much larger space. VRoxy represents the latest in remote, robotic embodiment.
    Donning a VR headset, a user has access to two view modes: Live mode shows an immersive image of the collaborative space in real time for interactions with local collaborators, while navigational mode displays rendered pathways of the room, allowing remote users to “teleport” to where they’d like to go. This navigation mode allows for quicker, smoother mobility for the remote user and limits motion sickness.
    The system’s automatic nature lets remote teammates focus solely on collaboration rather than on manually steering the robot, researchers said.
    “The great benefit of virtual reality is we can leverage all kinds of locomotion techniques that people use in virtual reality games, like instantly moving from one position to another,” said Mose Sakashita, a doctoral student in the field of information science at Cornell. “This functionality enables remote users to physically occupy a very limited amount of space but collaborate with teammates in a much larger remote environment.”
    Sakashita is the lead author of “VRoxy: Wide-Area Collaboration From an Office Using a VR-Driven Robotic Proxy,” to be presented at the ACM Symposium on User Interface Software and Technology (UIST), held Oct. 29 through Nov. 1.
    VRoxy’s automatic, real-time responsiveness is key for both remote and local teammates, researchers said. With a robot proxy like VRoxy, a remote teammate confined to a small office can interact in a group activity held in a much larger space, like in a design collaboration scenario. More

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    Certain online games use dark designs to collect player data

    Gaming is a $193 billion industry — nearly double the size of the film and music industries combined — and there are around three billion gamers worldwide. While online gaming can improve wellbeing and foster social relations, privacy and awareness issues could potentially offset these benefits and cause real harm to gamers.
    The new study, by scientists at Aalto University’s Department of Computer Science, reveals potentially questionable data collection practices in online games, along with misconceptions and concerns about privacy among players. The study also offers risk mitigation strategies for players and design recommendations for game developers to improve privacy in online games.
    ‘We had two supporting lines of inquiry in this study: what players think about games, and what games are really up to with respect to privacy,’ says Janne Lindqvist, associate professor of computer science at Aalto. ‘It was really surprising to us how nuanced the considerations of gamers were. For example, participants said that, to protect their privacy, they would avoid using voice chat in games unless it was absolutely necessary. Our game analysis revealed that some games try to nudge people to reveal their online identities by offering things like virtual rewards.’
    The authors identified instances of games using dark design — interface decisions that manipulate users into doing something they otherwise wouldn’t. These could facilitate the collection of player data and encourage players to integrate their social media accounts or allow data sharing with third parties.
    ‘When social media accounts are linked to games, players generally can’t know what access the games have to these accounts or what information they receive,’ says Amel Bourdoucen, doctoral researcher in usable security at Aalto. ‘For example, in some popular games, users can log in with (or link to) their social media accounts, but these games may not specify what data is collected through such integration.’
    The global gaming community has been subject to increased scrutiny over the past decade because of online harassment and the industry’s burnout culture. While these issues still linger, the push for more tech regulation in the EU and US has also brought privacy issues to the forefront.
    ‘Data handling practices of games are often hidden behind legal jargon in privacy policies,’ says Bourdoucen. ‘When users’ data are collected, games should make sure the players understand and consent to what is being collected. This can increase the player’s awareness and sense of control in games. Gaming companies should also protect players’ privacy and keep them safe while playing online.’ More

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    Controlling waves in magnets with superconductors for the first time

    Quantum physicists at Delft University of Technology have shown that it’s possible to control and manipulate spin waves on a chip using superconductors for the first time. These tiny waves in magnets may offer an alternative to electronics in the future, interesting for energy-efficient information technology or connecting pieces in a quantum computer, for example. The breakthrough, published in Science, primarily gives physicists new insight into the interaction between magnets and superconductors.
    Energy-efficient substitute
    “Spin waves are waves in a magnetic material that we can use to transmit information,” explains Michael Borst, who led the experiment. “Because spin waves can be a promising building block for an energy-efficient replacement for electronics, scientists have been searching for an efficient way to control and manipulate spin waves for years.”
    Theory predicts that metal electrodes give control over spin waves, but physicists have barely seen such effects in experiments until now. “The breakthrough of our research team is that we show that we can indeed control spin waves properly if we use a superconducting electrode,” says Toeno van der Sar, Associate Professor in the Department of Quantum Nanoscience.
    Superconducting mirror
    It works as follows: a spin wave generates a magnetic field that in turn generates a supercurrent in the superconductor. That supercurrent acts as a mirror for the spin wave: the superconducting electrode reflects the magnetic field back to the spin wave. The superconducting mirror causes spin waves to move up and down more slowly, and that makes the waves easily controllable. Borst: “When spin waves pass under the superconducting electrode, it turns out that their wavelength changes completely! And by varying the temperature of the electrode slightly, we can tune the magnitude of the change very accurately.”
    “We started with a thin magnetic layer of yttrium iron garnet (YIG), known as the best magnet on Earth. On top of that we laid a superconducting electrode and another electrode to induce the spin waves. By cooling to -268 degrees, we got the electrode into a superconducting state,” Van der Sar says. “It was amazing to see that the spin waves got slower and slower as it got colder. That gives us a unique handle to manipulate the spin waves; we can deflect them, reflect them, make them resonate and more. But it also gives us tremendous new insights into the properties of superconductors.”
    Unique sensor More

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    A superatomic semiconductor sets a speed record

    The search is on for better semiconductors. Writing in Science, a team of chemists at Columbia University led by Jack Tulyag, a PhD student working with chemistry professor Milan Delor, describes the fastest and most efficient semiconductor yet: a superatomic material called Re6Se8Cl2.
    Semiconductors — most notably, silicon — underpin the computers, cellphones, and other electronic devices that power our daily lives, including the device on which you are reading this article. As ubiquitous as semiconductors have become, they come with limitations. The atomic structure of any material vibrates, which creates quantum particles called phonons. Phonons in turn cause the particles — either electrons or electron-hole pairs called excitons — that carry energy and information around electronic devices to scatter in a matter of nanometers and femtoseconds. This means that energy is lost in the form of heat, and that information transfer has a speed limit.
    The search is on for better options. Writing in Science, a team of chemists at Columbia University led by Jack Tulyag, a PhD student working with chemistry professor Milan Delor, describes the fastest and most efficient semiconductor yet: a superatomic material called Re6Se8Cl2.
    Rather than scattering when they come into contact with phonons, excitons in Re6Se8Cl2 actually bind with phonons to create new quasiparticles called acoustic exciton-polarons. Although polarons are found in many materials, those in Re6Se8Cl2 have a special property: they are capable of ballistic, or scatter-free, flow. This ballistic behavior could mean faster and more efficient devices one day.
    In experiments run by the team, acoustic exciton-polarons in Re6Se8Cl2 moved fast — twice as fast as electrons in silicon — and crossed several microns of the sample in less than a nanosecond. Given that polarons can last for about 11 nanoseconds, the team thinks the exciton-polarons could cover more than 25 micrometers at a time. And because these quasiparticles are controlled by light rather than an electrical current and gating, processing speeds in theoretical devices have the potential to reach femtoseconds — six orders of magnitude faster than the nanoseconds achievable in current Gigahertz electronics. All at room temperature.
    “In terms of energy transport, Re6Se8Cl2 is the best semiconductor that we know of, at least so far,” Delor said.
    A Quantum Version of the Tortoise and the Hare
    Re6Se8Cl2 is a superatomic semiconductor created in the lab of collaborator Xavier Roy. Superatoms are clusters of atoms bound together that behave like one big atom, but with different properties than the elements used to build them. Synthesizing superatoms is a specialty of the Roy lab, and they are a main focus of Columbia’s NSF-funded Material Research Science and Engineering Center on Precision Assembled Quantum Materials. Delor is interested in controlling and manipulating the transport of energy through superatoms and other unique materials developed at Columbia. To do this, the team builds super-resolution imaging tools that can capture particles moving at ultrasmall, ultrafast scales. More