“Creating useful quantum computers and quantum simulators is one of the most important and debated topics in quantum science today, with the potential to revolutionise society,” says researcher Natalia Chepiga. Quantum simulators are a type of quantum computer, Chepiga explains: “Quantum simulators are meant to address open problems of quantum physics to further push our understanding of nature. Quantum computers will have wide applications in various areas of social life, for example in finances, encryption and data storage.”

Steering wheel

“A key ingredient of a useful quantum simulator is a possibility to control or manipulate it,” says Chepiga. “Imagine a car without a steering wheel. It can only go forward but cannot turn. Is it useful? Only if you need to go in one particular direction, otherwise the answer will be ‘no!’. If we want to create a quantum computer that will be able to discover new physics phenomena in the near-future, we need to build a ‘steering wheel’ to tune into what seems interesting. In my paper I propose a protocol that creates a fully controllable quantum simulator.”

Recipe

The protocol is a recipe — a set of ingredients that a quantum simulator should have to be tunable. In the conventional setup of a quantum simulator, rubidium (Rb) or cesium (Cs) atoms are targeted by a single laser. As a result, these particles will take up electrons, and thereby become more energetic; they become excited. “I show that if we were to use two lasers with different frequencies or colours, thereby exciting these atoms to different states, we could tune the quantum simulators to many different settings,” Chepiga explains.

The protocol offers an additional dimension of what can be simulated. “Imagine that you have only seen a cube as a sketch on a flat piece of paper, but now you get a real 3D cube that you can touch, rotate and explore in different ways,” Chepiga continues. “Theoretically we can add even more dimensions by bringing in more lasers.”

Simulating many particles

“The collective behaviour of a quantum system with many particles is extremely challenging to simulate,” Chepiga explains. “Beyond a few dozens of particles, modelling with our usual computer or a supercomputer has to rely on approximations.” When taking the interaction of more particles, temperature and motion into account, there are simply too many calculations to perform for the computer.

Quantum simulators are composed of quantum particles, which means that the components are entangled. “Entanglement is some sort of mutual information that quantum particles share between themselves. It is an intrinsic property of the simulator and therefore allows to overcome this computational bottleneck.”

Quantum processors based on two-dimensional arrays of optical tweezers, which are created using focussed laser beams, are one of the most promising technologies for developing quantum computing and simulation that will enable highly beneficial applications in the future. A diverse range of applications from drug development through to optimising traffic flows will benefit from this technology.

These processors have been able to hold several hundred single-atom quantum systems up to now, whereby each atom represents one quantum bit or qubit as the basic unit of quantum information. In order to make further advances, it is necessary to increase the number of qubits in the processors. This has now been achieved by a team headed by Professor Gerhard Birkl from the “Atoms — Photons — Quanta” research group in the Department of Physics at TU Darmstadt.

In a research article, which was first published at the beginning of October 2023 on the arXiv preprint server and has now also been published following scientific peer review in the journal OPTICA, the team reports on the world’s first successful experiment to realise a quantum-processing architecture that contains more than 1,000 atomic qubits in one single plane.

“We are extremely pleased that we were the first to break the mark of 1,000 individually controllable atomic qubits because so many other outstanding competitors are hot on our heels,” says Birkl about their results.

The researchers were able to demonstrate in their experiments that their approach of combining the latest quantum-optical methods with advanced micro-optical technology has enabled them to significantly increase the current limits on the accessible number of qubits.

This was achieved by introducing the novel method of “quantum bit supercharging.” It allowed them to overcome the restrictions imposed on the number of usable qubits by the limited performance of the lasers. 1305 single-atom qubits were loaded in a quantum array with 3,000 trap sites and reassembled into defect-free target structures with up to 441 qubits. By using several laser sources in parallel, this concept has broken through the technological boundaries that had been perceived as being almost insurmountable up to now.

For many different applications, 1,000 qubits is seen as the threshold value from which the boost to efficiency promised by quantum computers can now be demonstrated for the first time. Researchers around the world have thus been working intensively to be the first to break this threshold. The recently published research work demonstrates that for atomic qubits this breakthrough was achieved for the first time worldwide by the research group headed by Professor Birkl. The scientific publication also describes how further increases in the number of laser sources will enable qubit numbers of 10,000 and more in just a few years.

“We see some interesting signs of hot times in cool places,” said SwRI’s Dr. Christopher Glein, an expert in planetary geochemistry and lead author of a paper about this discovery. “I came into this project thinking that large Kuiper Belt objects (KBOs) should have ancient surfaces populated by materials inherited from the primordial solar nebula, as their cold surfaces can preserve volatiles like methane. Instead, the James Webb Space Telescope (JWST) gave us a surprise! We found evidence pointing to thermal processes producing methane from within Eris and Makemake.

The Kuiper Belt is a vast donut-shaped region of icy bodies beyond the orbit of Neptune at the edge of the solar system. Eris and Makemake are comparable in size to Pluto and its moon Charon. These bodies likely formed early in the history of our solar system, about 4.5 billion years ago. Far from the heat of our Sun, KBOs were believed to be cold, dead objects. Newly published work from JWST studies made the first observations of isotopic molecules on the surfaces of Eris and Makemake. These so-called isotopologues are molecules that contain atoms having a different number of neutrons. They provide data that are useful in understanding planetary evolution.

The JWST team measured the composition of the dwarf planets’ surfaces, particularly the deuterium (heavy hydrogen, D) to hydrogen (H) ratio in methane. Deuterium is believed to have formed in the Big Bang, and hydrogen is the most abundant nucleus in the universe. The D/H ratio on a planetary body yields information about the origin, geologic history and formation pathways of compounds containing hydrogen.

“The moderate D/H ratio we observed with JWST belies the presence of primordial methane on an ancient surface. Primordial methane would have a much higher D/H ratio,” Glein said. “Instead, the D/H ratio points to geochemical origins for methane produced in the deep interior. The D/H ratio is like a window. We can use it in a sense to peer into the subsurface. Our data suggest elevated temperatures in the rocky cores of these worlds so that methane can be cooked up. Molecular nitrogen (N₂) could be produced as well, and we see it on Eris. Hot cores could also point to potential sources of liquid water beneath their icy surfaces.”

Over the past two decades, scientists have learned that icy worlds can be much more internally evolved than once believed. Evidence for subsurface oceans has been found at several icy moons such as Saturn’s moon Enceladus and Jupiter’s moon Europa. Liquid water is one of the key ingredients in determining potential planetary habitability. The possibility of water oceans inside Eris and Makemake is something that scientists are going to study in the years ahead. If either of them is habitable, then it would become the most distant world in the solar system that could possibly support life. Finding chemical indicators of internally driven processes takes them a step in this direction.

“If Eris and Makemake hosted, or perhaps could still host warm, or even hot, geochemistry in their rocky cores, cryovolcanic processes could then deliver methane to the surfaces of these planets, perhaps in geologically recent times,” said Dr. Will Grundy, an astronomer at Lowell Observatory, one of Glein’s co-authors and lead author of a companion paper. “We found a carbon isotope ratio (¹³C/¹²C) that suggests relatively recent resurfacing.”

This work is part of a paradigm shift in planetary science. It is increasingly being recognized that cold, icy worlds may be warm at heart. Models developed for this study additionally point to the formation of geothermal gases on Saturn’s moon Titan, which also has abundant methane. Furthermore, the inference of unexpected activity on Eris and Makemake underscores the importance of internal processes in shaping what we see on large KBOs and is consistent with findings at Pluto.

“After the New Horizons flyby of the Pluto system, and with this discovery, the Kuiper Belt is turning out to be much more alive in terms of hosting dynamic worlds than we would have imagined,” said Glein. “It’s not too early to start thinking about sending a spacecraft to fly by another one of these bodies to place the JWST data into a geologic context. I believe that we will be stunned by the wonders that await!”

In a paper published Jan. 11 by Nature Nanotechnology, Biomedical Engineering Professor Ke Cheng and his research group demonstrate that using nanobubbles, called exosomes, through an inhalation treatment method can directly deliver IL-12 messenger RNA (mRNA) to the lungs. mRNAs are the blueprints for producing specific proteins that participate in a variety of cellular functions. While scientists have previously used liposomes (tiny fat-based particles) or lipid nanoparticles (LNPs) to deliver mRNA, this method has several problems, including a lack of tissue homing, where the particles do not go to the target organs, and concerns about the potential toxicity after long-term exposure. Over the past 15 years, Cheng’s group has been developing exosomes for use as superior drug delivery carriers over liposomes and LNPs in specific indications.

New approach

Up to now, clinicians have only been able to use IL-12 to treat cancer by injecting it directly into the tumor or into the bloodstream. Cheng’s lab found that having the patient — in this case, mice — inhale IL-12 mRNA in exosomes could not only deliver locally concentrated IL-12 into the lungs but also could better fight the cancer with minimal side effects. The inhalation method is more efficient in building higher concentrations of IL-12 right where it is needed than other ways of delivering mRNA such as using liposomes.

“Exosomes are usually injected systemically into the bloodstream,” said Cheng. “In this new study, we show that inhaled exosomes can efficiently reach the lung and deliver an anti-lung cancer cargo, IL-12 mRNA. This is a major step forward in advancing the development of new inhalable drugs to treat lung cancer, which has one of the lowest five-year survival rates in the world.”

Turning immune cells into powerful defenders

Inhaling the nanobubbles with the IL-12 blueprint can kickstart the lung immune cells, turning them into powerful defenders equipped to release substances that directly target and destroy tumor cells. In addition, IL-12 helps train these immune cells to “remember” the unique features of tumor cells. As a result, if the tumor tries to attack again, these well-informed immune cells are ready to recognize and eliminate the tumor swiftly. Additionally, these supercharged immune cells can spread their newfound knowledge to other, untrained immune cells throughout the body, creating an army of defenders. This means that even if tumor cells try to spread beyond their original location, like the lungs, these prepared immune cells can spot and wipe them out, offering a body-wide defense system against cancer.The mice that inhaled this therapy demonstrated lung tumor suppression as well as heightened resistance against tumor re-challenges.

Combining efficacy with simplicity

This strategy stands out as a potent IL-12 mRNA delivery system to the lung microenvironment, say the researchers, and combines simplicity with efficacy against primary tumors and metastases. Compared to other nanoparticle controls, exosomes boost IL-12 expression with mitigated toxicity. And patients are likely to be much happier with simply inhaling the therapeutic rather than receiving intratumoral injections.

Next steps

Cheng’s group is now working with Columbia University Irving Medical Center oncologists to translate their results into the clinic to benefit lung cancer patients.

The audio signals in online meetings and auditoriums that are not properly designed often have an echo lagging at least 100 milliseconds from the original speech. These echoes heavily distort speech, interfering with slowly varying sound features most important for understanding conversations, yet people still reliably understand echoic speech. To better understand how the brain enables this, the authors used magnetoencephalography (MEG) to record neural activity while human participants listened to a story with and without an echo. They compared the neural signals to two computational models: one simulating the brain adapting to the echo, and another simulating the brain separating the echo from the original speech.

Participants understood the story with over 95% accuracy, regardless of echo. The researchers observed that cortical activity tracks energy changes related to direct speech, despite the strong interference of the echo. Simulating neural adaptation only partially captured the brain response they observed — neural activity was better explained by a model that split original speech and its echo into separate processing streams. This remained true even when participants were told to direct their attention toward a silent film and ignore the story, suggesting that top-down attention isn’t required to mentally separate direct speech and its echo. The researchers state that auditory stream segregation may be important both for singling out a specific speaker in a crowded environment, and for clearly understanding an individual speaker in a reverberant space.

The authors add, “Echoes strongly distort the sound features of speech and create a challenge for automatic speech recognition. The human brain, however, can segregate speech from its echo and achieve reliable recognition of echoic speech.”

Typhoid fever is a common infection in many low- and middle-income countries and causes an estimated 135,000 deaths and 14 million infections globally each year. The World Health Organization has prequalified two typhoid vaccines, but for policymakers to plan effective vaccination strategies, they need accurate, high-resolution estimates of where the burden is highest.

Traditionally, people have cultured the bacterium that causes typhoid fever from blood samples to determine where the infection is most common, but in the new paper, researchers tried a more cost-effective surveillance approach. They tested environmental water samples from sewage and other locations to detect bacteriophages specific to the water-borne pathogen that causes typhoid fever, Salmonella Typhi.

The team tested 303 water samples from two locations in Bangladesh: the urban capital city, Dhaka, and a rural district, Mirzapur. They found that bacteriophages specific for Salmonella Typhi were present in 31% of environmental samples in Dhaka, compared to just 3% of samples from Mirzapur. This corresponds to results from more than 8,400 blood cultures, in which 5% of cultures from Dhaka and 0.05% from Mirzapur tested positive.

The new results suggest that detecting bacteriophages specific for Salmonella Typhi may be a rapid environmental surveillance method that could help decision makers understand the presence of typhoid fever in the community. The researchers propose that environment monitoring of bacteriophage could be a simple, cost-effective and scalable tool to assist policy decisions on typhoid control.

The authors add: “”Looking for bacteriophages in wastewater is a low-cost method for identifying typhoid hotspots without doing expensive blood cultures on thousands of people.”

A study published in the journal Science reveals that an area the size of France is under threat by forest restoration initiatives due to inappropriate restoration in the form of tree-planting.

Researchers analysed the areas of land committed to restoration via reforestation and found that many programmes include areas classified as non-forest systems. They believe that the inclusion of non-forest systems such as savannas and grasslands, which are threatened by increased tree cover, is the key issue.

They warn that planting trees in these grassy areas, which are structurally, functionally and compositionally distinct from forests, could be a risk to wildlife such as rhinos and wildebeest, as well as people who depend on these ecosystems.

Kate Parr, Professor of Tropical Ecology at the University’s School of Environmental Sciences and author of the study, said: “Restoration of ecosystems is needed and important, but it must be done in a way that is appropriate to each system.

“Non-forest systems such as savannas are misclassified as forest and therefore considered in need of restoration with trees.

“There is an urgent need to revise definitions so that savannas are not confused with forest because increasing trees is a threat to the integrity and persistence of savannas and grasslands.”

“Highlighting this issue now means there is still time to negate this threat and ensure that non-forest systems receive appropriate restoration.”

Dr Nicola Stevens, Trapnell Research Fellow in African Environments at the University of Oxford and co-author of the paper said: “The urgency of implementing large-scale tree planting is prompting funding of inadequately assessed projects that will most likely have negligible sequestration benefits and cause potential social and ecological harm.”

The study highlights that the issues raised are not unique to Africa and many other non-forest areas, for example the open savannas and grasslands of India and Brazil, could face a similar future due to inappropriate ‘restoration’ with trees.

The paper ‘Conflation of reforestation with restoration is widespread’ is published in the journal Science.

The study involved the University of Liverpool, the University of Oxford and Utrect University.

In a paper published in the journal Science, researchers at the University of Liverpool have discovered a solid material that rapidly conducts lithium ions. Such lithium electrolytes are essential components in the rechargeable batteries that power electric vehicles and many electronic devices.

Consisting of non-toxic earth-abundant elements, the new material has high enough Li ion conductivity to replace the liquid electrolytes in current Li ion battery technology, improving safety and energy capacity.

Using a transformative scientific approach to design the material, the interdisciplinary research team from the University synthesised the material in the laboratory, determined its structure (the arrangement of the atoms in space) and demonstrated it in a battery cell.

The new material is one of a very small number of solid materials that achieve Li ion conductivity high enough to replace liquid electrolytes, and operates in a new way because of its structure.

Its discovery was achieved through a collaborative computational and experimental workflow that used AI and physics-based calculations to support decisions made by chemistry experts at the University.

The new material provides a platform for the optimisation of chemistry to further enhance the properties of the material itself, and to identify other materials based on the new understanding provided by the study.

Professor Matt Rosseinsky, from the University of Liverpool’s Department of Chemistry, said: “This research demonstrates the design and discovery of a material that is both new and functional. The structure of this material changes previous understanding of what a high-performance solid-state electrolyte looks like.

“Specifically, solids with many different environments for the mobile ions can perform very well, not just the small number of solids where there is a very narrow range of ionic environments. This dramatically opens up the chemical space available for further discoveries.

Recent reports and media coverage herald the use of AI tools to find potentially new materials. In these cases, the AI tools are working independently and thus are likely to recreate what they were trained on in various ways, generating materials that may be very similar to known ones.

“This discovery research paper shows that AI and computers marshalled by experts can tackle the complex problem of real-world materials discovery, where we seek meaningful differences in composition and structure whose impact on properties is assessed based on understanding.”

“Our disruptive design approach offers a new route to discovery of these and other high-performance materials that rely on the fast motion of ions in solids.”

The study undertaken was a combined effort between researchers in University of Liverpool’s Department of Chemistry, Materials Innovation Factory, Leverhulme Research Centre for Functional Materials Design, Stephenson Institute for Renewable Energy, Albert Crewe Centre, and School of Engineering.

The work was funded by the Engineering and Physical Sciences Research Council (EPSRC), the Leverhulme Trust, and the Faraday Institution.

The findings, reported today in the journal Science, provide a new window into the electronic structure of molecules in the liquid phase on a timescale previously unattainable with X-rays. The new technique reveals the immediate electronic response when a target is hit with an X-ray, an important step in understanding the effects of radiation exposure on objects and people.

“The chemical reactions induced by radiation that we want to study are the result of the electronic response of the target that happens on the attosecond timescale,” said Linda Young, a senior author of the research and Distinguished Fellow at Argonne National Laboratory. “Until now radiation chemists could only resolve events at the picosecond timescale, a million times slower than an attosecond. It’s kind of like saying ‘I was born and then I died.’ You’d like to know what happens in between. That’s what we are now able to do.”

A multi-institutional group of scientists from several Department of Energy national laboratories and universities in the U.S. and Germany combined experiments and theory to reveal in real-time the consequences when ionizing radiation from an X-ray source hits matter.

Working on the time scales where the action happens will allow the research team to understand complex radiation-induced chemistry more deeply. Indeed, these researchers initially came together to develop the tools needed to understand the effect of prolonged exposure to ionizing radiation on the chemicals found in nuclear waste. The research is supported by the Interfacial Dynamics in Radioactive Environments and Materials (IDREAM) Energy Frontier Research Center sponsored by the Department of Energy and headquartered at Pacific Northwest National Laboratory (PNNL).

“Members of our early-career network participated in the experiment, and then joined our full experimental and theoretical teams to analyze and understand the data,” said Carolyn Pearce, IDREAM EFRC director and a PNNL chemist. “We couldn’t have done this without the IDREAM partnerships.”

From the Nobel Prize to the field

Subatomic particles move so fast that capturing their actions requires a probe capable of measuring time in attoseconds, a time frame so small that there are more attoseconds in a second than there have been seconds in the history of the universe.

The current investigation builds upon the new science of attosecond physics, recognized with the 2023 Nobel Prize in Physics. Attosecond X-ray pulses are only available in a handful of specialized facilities worldwide. This research team conducted their experimental work at the Linac Coherent Light Source (LCLS), located at SLAC National Accelerator Laboratory, in Menlo Park, Calif, where the local team pioneered the development of attosecond X-ray free-electron lasers.

“Attosecond time-resolved experiments are one of the flagship R&D developments at the Linac Coherent Light Source,” said Ago Marinelli from the SLAC National Accelerator Laboratory, who, together with James Cryan, led the development of the synchronized pair of X-ray attosecond pump/probe pulses that this experiment used. “It’s exciting to see these developments being applied to new kinds of experiments and taking attosecond science into new directions.”

The technique developed in this study, all X-ray attosecond transient absorption spectroscopy in liquids, allowed them to “watch” electrons energized by X-rays as they move into an excited state, all before the bulkier atomic nucleus has time to move. They chose the liquid water as their test case for an experiment.

“We now have a tool where, in principle, you can follow the movement of electrons and see newly ionized molecules as they’re formed in real-time,” said Young, who is also a professor in the Department of Physics and James Franck Institute at the University of Chicago.

These newly reported findings resolve a long-standing scientific debate about whether X-ray signals seen in previous experiments are the result of different structural shapes, or “motifs,” of water or hydrogen atom dynamics. These experiments demonstrate conclusively that those signals are not evidence for two structural motifs in ambient liquid water.

“Basically, what people were seeing in previous experiments was the blur caused by moving hydrogen atoms,” said Young. “We were able to eliminate that movement by doing all of our recording before the atoms had time to move.”

From simple to complex reactions

The researchers envision the current study as the beginning of a whole new direction for attosecond science.

To make the discovery, PNNL experimental chemists teamed with physicists at Argonne and the University of Chicago, X-ray spectroscopy specialists and accelerator physicists at SLAC, theoretical chemists at the University of Washington, and attosecond science theoreticians from the Hamburg Centre for Ultrafast Imaging and the Center for Free-Electron Laser Science (CFEL), Deutsches Elektronen-Synchrotron (DESY), in Hamburg, Germany.

During the global pandemic, in 2021 and into 2022, the PNNL team used techniques developed at SLAC to spray an ultra-thin sheet of pure water across the X-ray pump pulse path.

“We needed a nice, flat, thin sheet of water where we could focus the X-rays,” said Emily Nienhuis, an early-career chemist at PNNL, who started the project as a post-doctoral research associate. “This capability was developed at the LCLS.” At PNNL, Nienhuis demonstrated that this technique can also be used to study the specific concentrated solutions that are central to the IDREAM EFRC and will be investigated at the next stage of the research.

From experiment to theory

Once the X-ray data had been collected, theoretical chemist Xiaosong Li and graduate student Lixin Lu from the University of Washington applied their knowledge of interpreting the X-ray signals to reproduce the signals observed at SLAC. The CFEL team, led by theoretician Robin Santra, modelled the liquid water response to attosecond X-rays to verify that the observed signal was indeed confined to the attosecond timescale.

“Using the Hyak supercomputer at the University of Washington, we developed a cutting-edge computational chemistry technique that enabled detailed characterization of the transient high-energy quantum states in water,” said Li, the Larry R. Dalton Endowed Chair in Chemistry at the University of Washington and a Laboratory Fellow at PNNL. “This methodological breakthrough yielded a pivotal advancement in the quantum-level understanding of ultrafast chemical transformation, with exceptional accuracy and atomic-level detail.”

Principal Investigator Young originated the study and supervised its execution, which was led on-site by first author and postdoc Shuai Li. Physicist Gilles Doumy, also of Argonne, and graduate student Kai Li of the University of Chicago were part of the team that conducted the experiments and analyzed the data. Argonne’s Center for Nanoscale Materials, a DOE Office of Science user facility, helped characterize the water sheet jet target.

Together, the research team got a peek at the real-time motion of electrons in liquid water while the rest of the world stood still.

“The methodology we developed permits the study of the origin and evolution of reactive species produced by radiation-induced processes, such as encountered in space travel, cancer treatments, nuclear reactors and legacy waste,” said Young.

The study has three co-first authors: S. Li, Lu, and Swarnendu Bhattacharyya of DESY. The three corresponding authors are X. Li, Santra and Young. A full author list is available here.

This work was primarily supported by IDREAM, an Energy Frontier Research Center funded by the Department of Energy, Office of Science, Basic Energy Sciences program. Use of the LCLS, the SLAC National Accelerator Laboratory, and resources from the Center for Nanoscale Materials, Argonne National Laboratory, are supported by the DOE Office of Science, Basic Energy Sciences program. Additional support came from DESY and Cluster of Excellence, “CUI: Advanced Imaging of Matter,” of the Deutsche Forschungsgemeinschaft.

Mesophotic (‘middle-light’) coral ecosystems are light dependent tropical or subtropical habitats found at depths of 30 to 150 meters. They are unique because they host more native species compared to shallow-water coral ecosystems. Despite this, they are largely unexplored, and more research is needed to understand their basic biology.

Researchers studying corals access these invertebrate reef builders by snorkeling and scuba diving, but these methods have limitations, especially when identifying corals at deeper depths. Using genetic material that organisms shed from their bodies into their environment — environmental DNA or eDNA — scientists can identify types of corals and other organisms living in a particular habitat, providing a powerful tool for biodiversity assessment.

Importantly, studying the eDNA of corals offers unique advantages. First, unlike fish, corals are stationary, eliminating uncertainties about their location. Second, they constantly secrete mucus into the sea, providing plenty of coral eDNA for sampling. For this study, the researchers analyzed mitochondrial DNA, which is more abundant and of higher quality compared to nuclear DNA, improving the accuracy of their findings. To learn more about the coral eDNA metabarcording analysis methods used in this study, see here.

Faster and easier monitoring of coral reefs

Mesophotic coral ecosystems (MCEs) in Japan have some of the highest diversity of stony corals (Scleractinia) in the world, making them particularly important for researchers, but difficult to monitor because they are often located at deeper depths. Additionally, to accurately monitor corals, scientists require both scuba diving and taxonomy skills, which can be challenging. Existing methods for monitoring MCEs therefore impose limitations on conducting thorough surveys, and new methods are needed.

In October 2022, Prof. Noriyuki Satoh, leader of the Marine Genomics Unit, was approached by Mr. Shinichiro Nagahama of NTT Communications who had read about his research on coral eDNA methods. Mr. Nagahama suggested using their underwater drones to collect samples from deeper coral reefs for eDNA analysis. Prof. Satoh then put forward the idea of using the drones to conduct extensive surveys of mesophotic corals at greater depths.

Kerama National Park in Japan, about 30 km west of Okinawa Island, boasts some of the most transparent water in the Okinawa Archipelago. Often referred to as ‘Kerama blue’, these waters provided an excellent opportunity for the researchers to test this new sampling technique. They collected seawater samples — each measuring 0.5 liters — from 1 to 2 meters above the coral reefs (between 20 and 80 meters deep). The sampling sites were chosen across 24 locations within 6 different areas around the picturesque Zamami Island. The next step involved subjecting these samples to coral metabarcoding analyses, which uses Scleractinian-specific genetic markers to identify the different genera of corals present in each sample.

From the eDNA analysis results, the researchers successfully identified corals at the genus level. The presence and absence of certain genera of stony corals shown by this method indicated that reefs around the Kerama Islands exhibited different compositions of stony corals depending on location and depth. For example, the genus Acropora had the highest ratios at 11 sites, indicating that these corals are common at Zamami Island reefs. The researchers also found that the proportion of Acropora eDNA was higher at shallow reefs and upper ridges of slopes, while the proportion of the genus Porites increased at mesophotic sites. Regarding depth, Acropora was readily detected at shallow reefs (≤15 meters), while other genera were more frequently found at deeper reefs (>20 meters).

To study corals using eDNA metabarcoding methods, further sequencing of mitochondrial genomes of stony corals is needed, and this study suggests that it may be possible to more efficiently monitor mesophotic corals at the generic level using eDNA collected by underwater drones.

Collaborative innovation ahead

NTT Communications has developed a new version of the original drone used for this study. In response to a request from Prof. Satoh, an additional sampler was added so that two samples can be collected during a single dive. Additionally, the cable length between the controller and drone was extended from 150 meters to 300 meters and the battery is now changeable, so researchers can continue their survey work for an entire day.

Prof. Satoh is now working with two mesophotic coral specialists at the University of the Ryukyus, Dr. Frederick Singer and Dr. Saki Harii, to further test this method at study sites near Sesoko Island, using the new and improved drones. He hopes to revolutionize the way coral surveys are conducted. Currently, surveys are limited to very restricted spots, but with the help of these advanced underwater drones, scientists can extend their research from the shallowest regions to depths of 60 meters and beyond. “My ideal survey would include the entire spectrum of the coral reef, from the shallow waters to the mesophotic zones, and even the sandy depths. These machines provide an excellent method for conducting broader eDNA monitoring studies,” he remarked.