It’s possible that I shall make an ass of myself. But in that case one can always get out of it with a little dialectic. I have, of course, so worded my proposition as to be right either way (K.Marx, Letter to F.Engels on the Indian Mutiny)
Wednesday, July 28, 2021
Study: New reusable shock absorber shows promise in lab tests
The images show the device bending and snapping to dissipate energy. Credit: University at Buffalo
University at Buffalo engineers are reporting a new energy dissipation device that they say could have far-reaching applications in transportation safety.
Described in the International Journal of Mechanical Sciences, the device utilizes low-cost metallic materials and a simple design. Unlike conventional sacrificial structural components like car bumpers, it's designed to be reused after impact.
"Most energy absorbers carrying high stiffness work by crushing or collapsing upon impact. This reduces physical damage to the vehicle, or whatever the absorbers are protecting, but it requires the replacement of internal and external parts following the collision," says the study's senior author, Jongmin Shim, Ph.D., associate professor of structural engineering in the UB School of Engineering and Applied Sciences.
"Our structure is unique in that it enables impact energy to detour around the vehicle. It's comprised of one column with a flange at each end. These flanges have hinges that allow the normally rigid column to snap out of place, which converts external energy into kinetic energy of the disconnected column, eventually protecting the vehicle," he adds.
Study co-author Seoyoung Heo, Ph.D., is a former graduate student in Shim's lab.
"The device is engineered to have both high stiffness—the ability to bear loads and resist collapsing—as well as high damping, which means it can dissipate energy," she says. "Its potential applications are varied, everything from automobiles and ship buffers to helicopters, drones and more."
The researchers conducted tests of the device, made of steel, on examples measured by centimeters. Because of its simple design and common materials, they say, it could easily be scaled up or down to other dimensions.
Shim and Heo are co-inventors on a provisional patent application filed by UB with the U.S. Patent and Trademark Office for the device. The technology is available for licensing through the UB Technology Transfer office.
More information: Seoyoung Heo et al, Weakening-induced Snap Instability as a Novel Reusable Force Protection Mechanism, International Journal of Mechanical Sciences (2021). DOI: 10.1016/j.ijmecsci.2021.106645
Backyard trapping of rats and other pests is by far more popular as a conservation activity in urban areas than monitoring pests or native wildlife, according to Te Herenga Waka—Victoria University of Wellington research just published in the journal People and Nature.
"We were interested in whether different backyardconservationactivities appealed to different sorts of people in Aotearoa New Zealand and what motivated them to take part," says lead author Dr. Chris Woolley, a postdoctoral researcher at Zealandia—Centre for People and Nature in Wellington and a member of the team from the University's Te Tumu Whakaoho Mauri o te Ao Koiora—Centre for Biodiversity and Restoration Ecology (CBRE) that conducted the study.
Understanding what makes people want to take part in different nature-based activities is important for understanding how to get them involved and the sort of projects most likely to interest them, says Dr. Woolley.
Undertaken for the Ministry of Business, Innovation and Employment-funded People, Cities and Nature program, to which the CBRE contributes, the study investigated three main activities: pest mammal trapping and recording sightings of both native and pest species—all common ways in which urban-dwelling New Zealanders engage in backyard conservation.
"But there are some important differences," says Dr. Woolley. "Pest mammal trapping is a concrete action done to achieve a goal that will directly benefit native biodiversity. Monitoring activities, however, are examples of conservation citizen science—one (native biodiversity monitoring) collecting data to measure positive outcomes achieved; the other (pest mammal monitoring) measuring the presence or absence of a barrier to the former. Because of these differences, we wondered if the activities might appeal to different types of people."
In the study, 264 people—some self-selected and others reached by door knocking—responded to questions about how willing they would be to undertake the three activities.
"We wanted to know what motivated backyard conservation action and what barriers people felt prevented them from taking part," says Dr. Woolley.
Just over half the people said they had at some time taken part in native biodiversity monitoring, pest mammal monitoring and/or pest mammal trapping. Backyard pest trapping was by far the most commonly reported of the three activities.
People with a higher level of connection to nature were more willing to take part in all the activities. The link between connection to nature and a willingness to engage suggests that, in New Zealand, investing in programs that help improve people's connection to nature in urban areas might increase participation in conservation activities.
"People cited a number of different barriers to participation, including lack of knowledge and motivation," says Dr. Woolley. "Concern for the safety of children and pets was reported as a barrier more frequently for pest trapping than pest monitoring—and animal welfare concerns, cost and dealing with dead animals were an issue."
Lack of time and of a suitable environment were also seen as barriers to participation in each of the conservation activities.
"What this suggests is that—when developing conservation activities involving public participation—the ways in which you communicate the outcomes of the activity will be important in encouraging participation. Monitoring might be for people with an interest in natural history who can then get feedback on their observations," says Dr. Woolley.
The survey results also suggested a pro-environmental attitude has less influence on people's willingness to trap than for the other activities, indicating the popularity of trapping may be driven by other factors—perhaps a perception of rodents as household pests.
"We expected that community and social motivations might be positively associated with pest trapping, as, anecdotally, this activity seems to provide opportunities for the community to get to know one another," write the authors, who also include CBRE director Associate Professor Stephen Hartley, Professor Nicola Nelson, head of the University's Te Kura Mātauranga Koiora—School of Biological Sciences, of which the CBRE is part, and Zealandia conservation manager Dr. Danielle Shanahan.
"Instead, these relationships existed for the monitoring activities but not for trapping. This indicates that although people who engage in pest trapping may enjoy social opportunities as a result of taking part, this is unlikely to be a factor motivating their initial participation."
"Ironically," says Dr. Woolley, "for those who prefer trapping, success from a conservation point of view is when you're not trapping anything because there's nothing to be trapped! That's where you need the monitoring and in a large project ideally you'd do all three methods."
Providing easy-to-use traps and more information and publicity about trapping will also help get people involved, say the researchers, who think these sorts of activities may act as a gateway, encouraging people with low conservation values to begin a path towards greater environmental stewardship.
More information: Christopher K. Woolley et al, Public willingness to engage in backyard conservation in New Zealand: Exploring motivations and barriers for participation, People and Nature (2021). DOI: 10.1002/pan3.10243
The proposed polymer, with its backbone shown in blue, creates regions with a high local density of copper side units (pendants). This helps reduce Cu(II) to Cu(I), the most difficult step in the redox reaction shown, to ultimately produce more hydroxyl radicals (-OH). Credit: Assistant Professor Shigehito Osawa
The discovery of antibiotics was a huge breakthrough in medicine, which helped save countless lives. Unfortunately, their widespread use has led to the rapid evolution of highly resistant bacterial strains, which threaten to take humanity back to square one in the fight against infectious diseases. Even though researchers are seeking new design concepts for antibacterial drugs, the overall development of new agents is currently on the decline.
To tackle this serious problem, scientists at Tokyo University of Science, Japan, are exploring a novel approach to boost the in vivo antibacterial activity of hydrogen peroxide (H2O2), a commonly used disinfectant. In a recent study published inMacromolecular Rapid Communications, a team led by Assistant Professor Shigehito Osawa and Professor Hidenori Otsuka reported their success in enhancing H2O2activity using carefully tailoredcopper-containing polymers.
To understand their approach, it helps to know how H2O2 acts against bacteria in the first place, and the role that copper plays. H2O2 can be decomposed into a hydroxyl radical (OH) and a hydroxide anion (OH−), the former of which is highly toxic to bacteria as it readily destroys certain biomolecules. Copper in its first oxidation state, Cu(I), can catalyze the splitting of H2O2 into a hydroxyl radical and a hydroxide anion, turning into Cu(II) in the process through oxidation. Curiously, H2O2 can also catalyze the reduction of Cu(II) to Cu(I), but only if this reaction is somehow facilitated. One way to achieve this is to have Cu(II)-containing complexes get close enough together.
However, when using Cu(II)-containing complexes dissolved in a solution, the only way for them to come close together is by accidentally bumping into each other, which requires an excessively high concentration of copper. The team found a workaround to this issue by drawing inspiration from cellular chemistry, as Dr. Osawa explains: "In living organisms, copper forms complexes with proteins to efficiently catalyze redox reactions. For example, tyrosinase has two copper complex sites in close proximity to each other, which facilitates the formation of reaction intermediates between oxygen species and copper complexes. We thought we could leverage this type of mechanism in artificially produced polymers with copper complexes, even if dispersed in a solution."
With this idea, the researchers developed a long polymer chain with dipicolylamine (DPA) as copper-containing complexes. These DPA–copper complexes were attached to the long polymer backbone as "pendant groups." When these polymers are dispersed in a solution, the Cu(II) atoms in the pendant groups are kept in close proximity and locally high densities, vastly increasing the chances that two of them will be close enough to be reduced to Cu(I) by H2O2. Through various experiments, the scientists demonstrated that the use of these tailored polymers resulted in higher catalytic activity for the splitting of H2O2, resulting in more OH even for lower concentrations of copper. Further tests using Escherichia coli cultures showed that these polymers greatly enhanced the antibacterial potential of H2O2.
While the results of this study open up a new design avenue for antimicrobial drugs, there may also be useful applications in the food industry as well. "Because copper is an essential nutrient for living organisms, the antibacterial agent developed in this study holds promise as an efficient food preservative, which could contribute to increasing the variety of foods that can be preserved over long shelf times," highlights Dr. Osawa. Let us hope this new strategy makes it easier for us to keep microscopic menaces at bay.
More information: Shigehito Osawa et al, Accelerated Redox Reaction of Hydrogen Peroxide by Employing Locally Concentrated State of Copper Catalysts on Polymer Chain, Macromolecular Rapid Communications (2021). DOI: 10.1002/marc.202100274
Nitrogen deficiency can limit sunflower yield and quality. Researchers conducted experiments to evaluate tools for nitrogen diagnosis. Credit: Nahuel Reussi Calvo
Sunflowers have many uses. They are used for floral arrangements, animal feed, biofuels, and even food for us.
When grown commercially by farmers, the quality of sunflowers is based on the oil and protein concentrations in the seeds.
Sunflower oil can be used for cooking and can be made into biofuels. The protein from sunflowers is important in sunflower products like animal pellets and protein powders.
To grow quality sunflowers with a high nutritional value, farmers need to ensure the sunflowers have access to nutrients in the soil. One of the most important nutrients for sunflowers is nitrogen.
Sunflowers cannot survive without nitrogen, but too much can be a problem. Too much nitrogen can actually decrease the oil concentration in seeds, which decreases the quality of the crop.
Nahuel Reussi Calvo is a scientist in Argentina who studies sunflowers. His research aims to determine the best rate of nitrogen fertilizer that will grow high-quality sunflowers. The results were recently shared in Agronomy Journal, a publication of the American Society of Agronomy.
Finding the best nitrogen fertilizer rate has benefits beyond sunflower yields. It also minimizes the economic and environmental costs of applying fertilizer.
Modern varieties of sunflower can produce more oil and protein, but they require more nitrogen to do so.
Traditionally, scientists measure nitrogen available for sunflowers by taking soil samples before planting. However, the target nitrogen levels for these tests are not up-to-date to match the needs of modern sunflowers.
Researchers set out to determine if there were better ways to determine how much nitrogen the sunflowers need. They tested a few different methods.
First, Reussi Calvo and the team used the traditional soil sample analysis method combined with another soil sample analysis. The extra soil sample helps determine the amount of nitrogen provided in the soil when organic matter naturally breaks down.
The next method took place during the growing season. The team used sensors to measure leaf greenness at different growth stages. This is a test that has proved successful for measuring nitrogen content in crops like wheat, barley, corn, and potato.
After harvest, the team used sunflower seeds to measure grain nitrogen concentration for the third method. This is a useful tool for predicting the nutritional value of crops like corn, wheat, rice, and cotton.
Researchers determined the three new methods for measuring nitrogen for sunflowers were better than the traditional soil sample analysis method. Leaf greenness sensors were a promising tool for monitoring nitrogen during the growing season. The grain nitrogen concentration successfully diagnosed nitrogen deficiencies.
Argentina is the fourth largest sunflower producer in the world, but the average yield is much lower than other countries. By updating nitrogen recommendations for sunflower crops, scientists can decrease the yield gap and improve sunflower grain quality.
The next steps in this research will be to repeat the study on farms with different soil types, management practices, and levels of other nutrients like phosphorus and sulfur.
More information: Sergio Tovar Hernandez et al, Assessment of nitrogen diagnosis methods in sunflower, Agronomy Journal (2021). DOI: 10.1002/agj2.20685
Oral biome change during shift from foraging to farming not as dramatic as in recent years
Disarticulated mandible x.11 in context U64 (c. 6750--6450 cal BC) from the Mesolithic site of Vlasac, Serbia. Credit: Dušan Boric
A team of researchers affiliated with several institutions in Italy, the US and Austria has found that changes to the human oral biome during the shift from foraging to farming were not nearly as dramatic as those that have occurred in modern times. In their paper published in Proceedings of the National Academy of Sciences, the group describes their analysis of dental records covering thousands of years and what it showed them about changes to the microbiome in the human mouth.
Modern humans began the transition from foraging to farming during the Neolithic—at the end of the Stone Age, approximately 10,000 years ago. In this new effort, the researchers wondered if the oral microbiome of people changed as people began eating more food they grew themselves. To find out, they conducted an extensive DNA analysis of dental calculus (mineralized plaque) from the remains of 28 ancient people found in what is now the Danube Gorges region which covers parts of Croatia and Romania—along with 10 samples from people who once lived in central Italy and a dozen from people who once lived in what is now northwestern Italy. The age of the specimens ran from the Neolithic all the way to the Middle Ages.
In looking at their data, the researchers found that the gradual change to farming did not impact the human oral biome in any significant way. The most noticeable was an uptick in microbes of the 807-oral taxon—which diversified geographically—as well as the discovery that Streptococcus sanguinis became more common in foragers during the Mesolithic. Also, they saw that the Anaerolineaceae bacterium became more diverse and, in some cases, displaced other variants. They also noticed slight differences in multiple species between people who lived in Italy and those who lived in the Balkans. None of the changes they saw came close, however, to the changes that have occurred in the much more recent past—since antibiotics have been introduced into the oral biome. Antibiotic resistance in microbes has led to significant evolutionary changes.
More information: Claudio Ottoni et al, Tracking the transition to agriculture in Southern Europe through ancient DNA analysis of dental calculus, Proceedings of the National Academy of Sciences (2021). DOI: 10.1073/pnas.2102116118
Scientist aids in ID of child in the state's oldest cold case
by Kristin Strommer, Museum Of Natural and Cultural History, University of Oregon
Credit: University of Oregon
A toddler who was found dead in Oregon 58 years ago has finally been identified, thanks to a concerted effort involving local, state and national law enforcement, genetic genealogists and a University of Oregon scientist.
Jeanne McLaughlin, an osteologist and forensic anthropologist at the Museum of Natural and Cultural History, was called to assist with the case beginning in 2008, after the Jackson County Sheriff's Office exhumed the body in order to obtain a DNA sample. Osteology is the study of theskeletonand bones.
First discovered in 1963 by a fisherman at Keene Creek Reservoir in Southern Oregon, the child's body was found wrapped in blankets and wire and weighted down with iron molds. Despite efforts by generations of investigators, the Baby Doe's identity remained unknown for decades, becoming the oldest unidentified person case in the state.
All that all changed in June, when the Jackson County Sheriff's Office announced its conclusion that Baby Doe was 2-year-old Steven Crawford, a missing child who had been born in New Mexico in 1960.
"Advances in DNA science were central to solving the case," McLaughlin said.
Following exhumation, McLaughlin helped the investigative team develop a more precise biological profile. Beginning with a round of X-rays, she looked for signs of trauma and other clues about the child's life and death, but she and the team soon determined that they needed more information than X-rays could reveal. So she processed the remains down to a skeleton, which enabled closer examination, extraction of a DNA sample and development of a digital facial reproduction.
Her analysis of the skeleton led McLaughlin to expand the initially assigned age range from 2 years to between 18 months and 2 1/2 years. Her examination also revealed that the child had some distinct features, including two fused teeth and a unique skull shape, which suggested he may have lived with a genetic syndrome.
"Down syndrome was at the top of the list, though we couldn't entirely rule out others without further genetic testing," McLaughlin said.
The DNA was compared across national databases of missing and unidentified persons, but the lead went cold when no matches were found.
"Cold cases typically go in spurts and stalls. You get some new tip or some new technology comes along that breathes life into the case and then you go into a waiting period again," said McLaughlin, who has worked on investigations around the state and the country.
The Baby Doe case finally got its big break in 2020, when the Jackson County Sheriff's Office received a tip through one of its social media accounts and reopened the investigation. The investigative team soon submitted another biological sample, this time in hopes of generating new leads through DNA.
"This time it paid off," McLaughlin said. "The genealogy was the ticket."
CeCe Moore, a genetic genealogist at Parabon NanoLabs, searched an open-source DNA repository and located two potential siblings of the unidentified toddler. A subsequent interview with a half-brother in Ohio revealed that he had a younger brother with Down syndrome who'd gone missing decades prior. Soon after, investigators located Stevie Crawford's birth certificate.
"Since then, many more family members have been located, and the family has been very involved since the identification was made," McLaughlin said.
She noted that families often experience relief when a missing person case finally resolves.
"They have an answer," she said. "Not knowing has to be the worst kind of torture. I can't imagine hearing, after 58 years, "Here's your loved one. We know where he is, we know a little bit about what happened.'"
McLaughlin commended the efforts of the many people involved in the case over the years, noting the longevity of the investigation and the ongoing energy put into the case.
"It had been through multiple teams of investigators spanning three generations, but cases like these stick with you," she said. "Investigators stay invested. And this case in particular showcases what can happen when everyone comes together for a common cause."
GMN station locations in North America and coverage area at the height of 100 km. Credit: University of Western Ontario
As billionaires battle it out in a space race that only a handful of the world's richest persons can play, a highly inclusive international project is looking in the other direction–what's flying towards Earth–and all are welcome.
Led by Western University's Denis Vida, the Global Meteor Network (GMN) is a collection of more than 450 video meteor cameras hosted by amateur astronomers and professionals alike in 23 countries across the globe.
That's a lot of cameras and more, much more, are on the way. The massive array, working collectively and connectively, is needed to achieve GMN's mission prime: ensuring that no unique space events, such as rare meteor showers or meteorite-dropping fireballs, are missed.
"The main operational goal of the project is to establish a decentralized, science-grade instrument which observes the night sky every night of the year from as many locations around the world as possible," said Vida, a postdoctoral associate in Western's department of physics and astronomy.
A new paper, soon-to-be published by Monthly Notices of the Royal Astronomical Society and currently available at arXiv, details the project and also shares some of GMN's impressive preliminary findings.
Meteor astronomers, like Vida and Western's Canada Research Chair in Planetary Small Bodies Peter Brown, have a unique challenge to get their data. Unlike other fields of astronomy, where the objects of interest, like planets or distant galaxies, are usually so far away that they can be observed from virtually any point on the globe, meteors occur much closer to Earth, and most burn up in the atmosphere at heights of around 100 km.
Video showing the aurora captured by a GMN camera in Alaska. Credit: Bill Witte.
"Other astronomers can pool their resources to build a big telescope on top of a mountain where the skies are dark and clear year-round, but meteor astronomers need spatial coverage most of all," said Vida.
A bright, meteorite-dropping fireball can occur anywhere in the world, and can only be well observed from within a distance of 300 km. To get the exact fall location and the orbit, it needs to be observed by at least two cameras in two different locations. That's exactly what GMN provides.
Just a few months ago, the Winchcombe meteorite made international headlines. Several GMN cameras in the UK tracked the fireball together with other meteor networks, leading to important data retrieval and its eventual discovery on Earth. Spurred by the Winchcombe event, more than 150 meteor enthusiasts in the UK now want to install GMN cameras.
"There are already more than 100 existing ones in the UK, so that's really exciting," said Vida. "Its role in the recovery and analysis of the Winchcombe meteorite fall is proof positive that GMN works."
GMN started when Vida was an undergraduate student. The first system was installed at Western in 2017, and GMN has continued to grow since with cameras now in Ontario, Quebec and Alberta, as well as the United States, the UK, Spain, Belgium, Croatia and Brazil.
"A few friends and I realized that we can use low-cost Raspberry Pi single-board computers and reduce the cost of a single meteor observing system by 10 times, allowing us to install many more cameras than was previously possible," said Vida.
Raspberry Pi computers are considered the most popular single-board systems and are often used in DIY projects or as a cost-effective system for learning to code.
An animated gif of a meteorite dropping fireball observed in Ontario in January 2020. Credit: University of Western Ontario
Beyond the thrilling visuals, GMN provides the world's meteor community with real-time awareness of the near-Earth meteoroid environment by publishing orbits of all observed meteors from around the globe within 24 hours of observation. The network also observes meteor showers in an effort to better understand flight patterns, flux capacities, and even predict future events.
The location of all the cameras and the latest data is available for anyone to explore, via the GMN website.
Loggerhead sea turtles (Caretta caretta) are opportunistic carnivores that primarily feed on invertebrates and fish. In the wild, they eat a variety of food items depending on their life stage and geographic location. For debilitated sea turtles in rehabilitation, part of the healing process is to provide a species-specific, balanced diet that provides nutrition similar to that of a wild diet to allow injured, ill, malnourished and incapacitated turtles to gain weight and improve body condition. However, developing the right nutritionally balanced formula is challenging.
To find answers, a team of scientists led by Florida Atlantic University's Harbor Branch Oceanographic Institute followed their 'gut' instinct. They hypothesized that analyzing the stomach contents and clinical pathology data of wild loggerhead turtles would enable development of nutritional indices that could be applied to better address the dietary needs of captive loggerheads.
For the study, published in the Journal of Animal Physiology and Animal Nutrition, they examined the stomach contents of 153 deceased loggerheads that stranded in coastal Georgia. Stomach contents information was used to determine common local prey items, which were then evaluated for nutritional content. They also compared hematology and plasma biochemistry profiles (including proteins, trace minerals, and vitamins) between four cohorts of loggerhead turtles, including free-ranging subadults and adults, nesting females, and loggerheads undergoing rehabilitation at the Georgia Sea Turtle Center on Jekyll Island.
Comparisons from the study will enable scientists and clinicians to relate different life history stages to differences in blood health analytes, including several nutritional parameters not previously reported for loggerheads in this region. Results were also used to formulate a regionally specific, formulated diet for tube feeding, and a supplement containing vitamins and minerals for captive loggerheads, to more closely approximate the nutritional content of their natural diet. A vitamin/mineral supplement and a critical care diet were designed based on these data (Mazuri 5B48 Sea Turtle Supplement and Mazuri 5S94 Sea Turtle Meal Diet for Carnivorous Turtles).
"Data from our study can be used to enable caretakers to more closely approximate a 'normal' diet for captive loggerhead turtles, including providing vitamin and mineral supplementation when appropriate," said Annie Page-Karjian, D.V.M., Ph.D., senior author, clinical veterinarian and an assistant research professor, FAU Harbor Branch. "Of course, understanding the current nutrient profile of diet items being fed is of critical importance as fish and other food items for aquatic species can vary dramatically with regards to micronutrient and macronutrient content."
The research team from FAU Harbor Branch and the University of California, Davis; Georgia Sea Turtle Center; Georgia Aquarium; Marine Resources Division, South Carolina Department of National Resources, Marine Resource Research Institute; and EnviroFlight, identified a total of 288 different forage items. Crabs were by far the most common prey item, followed by fish, shrimp, gastropods such as snails and slugs, horseshoe crabs, bivalve mollusks such as clams, oysters, and mussels, and other invertebrates including tunicates, sponges, sea cucumbers, and soft coral.
The proportion of certain prey items differed significantly with turtle size; adult turtles ate proportionately more gastropods, and subadults ate proportionately more fish. None of the other proportions significantly differed between size classes. No gastropods, bivalve mollusks, or mixed invertebrates were identified in stomach contents of turtles in "poor" body condition, and turtles in "good" body condition ate proportionately more gastropods.
Of the 153 loggerheads, 76 (49.7 percent) had only one kind of identifiable forage item in their gastrointestinal tract, 42 (27.4 percent) had two, 22 (14.4 percent) had three, five (3.2 percent) had four, four (2.6 percent) had five, two (1.3 percent) had six, one (0.7 percent) had seven, and one (0.7 percent) had eight different kinds of forage items.
Seasonal effects were apparent in relative abundance of certain prey items, such as crabs in cooler months and bivalve mollusks in warmer months. Assessing the regional and temporal variability in loggerhead diets is an important component in their effective conservation because resultant data also can be used to help understand the impacts of environmental perturbations on benthic food webs.
"Results from our study support the hypothesis that loggerhead diet composition shifts and adapts over time to changing prey availability," said Page-Karjian. "In turn, such fluctuations in the food web may be related to environmental shifts such as climate change and also to human activities such as trawl fishing, which alters the food web composition by removing benthic crustaceans along with bycatch, and dredging, a practice that totally destroys benthic habitats."
Differences identified in the clinical pathology data from the study also highlight the need to develop baseline blood parameter reference intervals that are specific to the life history stage, which can be applied in a rehabilitation setting to help interpret clinical data for stranded loggerheads in various physiological states.
More information: Christine M. Molter et al, Health and nutrition of loggerhead sea turtles ( Caretta caretta ) in the southeastern United States, Journal of Animal Physiology and Animal Nutrition (2021). DOI: 10.1111/jpn.13575
An international study led by The University of Western Australia has found that temperate marine ecosystems dominated by marine forests are collapsing into flattened seascapes of short turf algae across the globe.
The study, published in Global Change Biology, reveals that in Western Australia alone, thousands of hectares of underwater forests have collapsed into short carpets of seaweed turf.
Some of the other worst affected areas globally include southern Norway, eastern North America, the Mediterranean Sea and southern parts of Japan.
Lead author Albert Pessarrodona, from the UWA Oceans Institute and School of Biological Sciences, said marine forests were formed by large seaweeds that towered up above the ocean floor, forming underwater canopies that house many species of fish, invertebates and algae.
"Although many studies have reported the local decline of these forests, ours is the first to quantify its global consequences," Mr Pessarrodona said.
"Not only is seaweed turf replacing marine forests in many areas of the globe, but once turfs are able to expand, the seascape structure of those areas converges into very similar and simpler habitats, stripping oceans of the rich diversity of habitats supporting sea life."
Mr Pessarrodona said the results of the study were concerning, and could be attributed to a variety of impacts that varied from place to place, but humans were often the root cause.
"It's like your local woodland turning into garden turf—that is essentially what is happening under water."
Co-author Dr. Karen Filbee-Dexter, from the UWA Oceans Institute, said once turf algae was established, their carpets acted as sediment traps, retaining sediment in between the short algal filaments.
"In the affected areas in Western Australia, turf habitats now additionally retain approximately 242 million tons of sediment, which is 1,000 times more than what is delivered through the rivers every year," Dr. Filbee-Dexter said.
Co-author Professor Thomas Wernberg said all this sediment on the reef had been shown to limit the re-establishment of forest-forming species and feeding by fishes.
The scientists are currently working on ways to restore forests in the face of this global phenomenon, including the devolopment of "green gravel," an innovative new restoration tool.
More information: Albert Pessarrodona et al, Homogenization and miniaturization of habitat structure in temperate marine forests, Global Change Biology (2021). DOI: 10.1111/gcb.15759
In certain parts of the deep ocean, scattered across the seafloor, lie baseball-sized rocks layered with minerals accumulated over millions of years. A region of the central Pacific, called the Clarion Clipperton Fracture Zone (CCFZ), is estimated to contain vast reserves of these rocks, known as "polymetallic nodules," that are rich in nickel and cobalt—minerals that are commonly mined on land for the production of lithium-ion batteries in electric vehicles, laptops, and mobile phones.
As demand for these batteries rises, efforts are moving forward to mine the ocean for these mineral-rich nodules. Such deep-sea-mining schemes propose sending down tractor-sized vehicles to vacuum up nodules and send them to the surface, where a ship would clean them and discharge any unwanted sediment back into the ocean. But the impacts of deep-sea mining—such as the effect of discharged sediment on marine ecosystems and how these impacts compare to traditional land-based mining—are currently unknown.
Now oceanographers at MIT, the Scripps Institution of Oceanography, and elsewhere have carried out an experiment at sea for the first time to study the turbulent sediment plume that mining vessels would potentially release back into the ocean. Based on their observations, they developed a model that makes realistic predictions of how a sediment plume generated by mining operations would be transported through the ocean.
The model predicts the size, concentration, and evolution of sediment plumes under various marine and mining conditions. These predictions, the researchers say, can now be used by biologists and environmental regulators to gage whether and to what extent such plumes would impact surrounding sea life.
"There is a lot of speculation about [deep-sea-mining's] environmental impact," says Thomas Peacock, professor of mechanical engineering at MIT. "Our study is the first of its kind on these midwater plumes, and can be a major contributor to international discussion and the development of regulations over the next two years."
The team's study appears today in Nature Communications: Earth and Environment.
Peacock's co-authors at MIT include lead author Carlos Muñoz-Royo, Raphael Ouillon, Chinmay Kulkarni, Patrick Haley, Chris Mirabito, Rohit Supekar, Andrew Rzeznik, Eric Adams, Cindy Wang, and Pierre Lermusiaux, along with collaborators at Scripps, the U.S. Geological Survey, and researchers in Belgium and South Korea.
Out to sea
Current deep-sea-mining proposals are expected to generate two types of sediment plumes in the ocean: "collector plumes" that vehicles generate on the seafloor as they drive around collecting nodules 4,500 meters below the surface; and possibly "midwater plumes" that are discharged through pipes that descend 1,000 meters or more into the ocean's aphotic zone, where sunlight rarely penetrates.
In their new study, Peacock and his colleagues focused on the midwater plume and how the sediment would disperse once discharged from a pipe.
"The science of the plume dynamics for this scenario is well-founded, and our goal was to clearly establish the dynamic regime for such plumes to properly inform discussions," says Peacock, who is the director of MIT's Environmental Dynamics Laboratory.
Credit: Massachusetts Institute of Technology
To pin down these dynamics, the team went out to sea. In 2018, the researchers boarded the research vessel Sally Ride and set sail 50 kilometers off the coast of Southern California. They brought with them equipment designed to discharge sediment 60 meters below the ocean's surface.
"Using foundational scientific principles from fluid dynamics, we designed the system so that it fully reproduced a commercial-scale plume, without having to go down to 1,000 meters or sail out several days to the middle of the CCFZ," Peacock says.
Over one week the team ran a total of six plume experiments, using novel sensors systems such as a Phased Array Doppler Sonar (PADS) and epsilometer developed by Scripps scientists to monitor where the plumes traveled and how they evolved in shape and concentration. The collected data revealed that the sediment, when initially pumped out of a pipe, was a highly turbulent cloud of suspended particles that mixed rapidly with the surrounding ocean water.
"There was speculation this sediment would form large aggregates in the plume that would settle relatively quickly to the deep ocean," Peacock says. "But we found the discharge is so turbulent that it breaks the sediment up into its finest constituent pieces, and thereafter it becomes dilute so quickly that the sediment then doesn't have a chance to stick together."
Dilution
The team had previously developed a model to predict the dynamics of a plume that would be discharged into the ocean. When they fed the experiment's initial conditions into the model, it produced the same behavior that the team observed at sea, proving the model could accurately predict plume dynamics within the vicinity of the discharge.
The researchers used these results to provide the correct input for simulations of ocean dynamics to see how far currents would carry the initially released plume.
"In a commercial operation, the ship is always discharging new sediment. But at the same time the background turbulence of the ocean is always mixing things. So you reach a balance. There's a natural dilution process that occurs in the ocean that sets the scale of these plumes," Peacock says. "What is key to determining the extent of the plumes is the strength of the ocean turbulence, the amount of sediment that gets discharged, and the environmental threshold level at which there is impact."
Based on their findings, the researchers have developed formulae to calculate the scale of a plume depending on a given environmental threshold. For instance, if regulators determine that a certain concentration of sediments could be detrimental to surrounding sea life, the formula can be used to calculate how far a plume above that concentration would extend, and what volume of ocean water would be impacted over the course of a 20-year nodule mining operation.
"At the heart of the environmental question surrounding deep-sea mining is the extent of sediment plumes," Peacock says. "It's a multiscale problem, from micron-scale sediments, to turbulent flows, to ocean currents over thousands of kilometers. It's a big jigsaw puzzle, and we are uniquely equipped to work on that problem and provide answers founded in science and data."
The team is now working on collector plumes, having recently returned from several weeks at sea to perform the first environmental monitoring of a nodule collector vehicle in the deep ocean in over 40 years.
This research was supported in part by the MIT Environmental Solutions Initiative, the UC Ship Time Program, the MIT Policy Lab, the 11th Hour Project of the Schmidt Family Foundation, the Benioff Ocean Initiative, and Fundación Bancaria "la Caixa."
More information: Carlos Muñoz-Royo et al, Extent of impact of deep-sea nodule mining midwater plumes is influenced by sediment loading, turbulence and thresholds, Communications Earth & Environment (2021). DOI: 10.1038/s43247-021-00213-8
