Scientists investigate potential regolith origin on Uranus' moon Miranda

by Laurence Tognetti, Universe Today

Credit: NASA/JPL-Caltech

In a recent study published in The Planetary Science Journal, a pair of researchers led by The Carl Sagan Center at the SETI Institute in California investigated the potential origin for the thick regolith deposits on Uranus' moon, Miranda. The purpose of this study was to determine Miranda's internal structure, most notably its interior heat, which could help determine if Miranda harbors—or ever harbored—an internal ocean.

"It is unlikely that Miranda would be able to retain a subsurface ocean to the present day due to its small size," said Dr. Chloe Beddingfield, who is a scientist at the NASA Ames Research Center. "However, a thick regolith layer would act like an insulating blanket, trapping heat inside Miranda and enhancing the longevity of a subsurface ocean for some period. This trapped heat would have also promoted endogenic activity for longer periods of time on Miranda, such as the geologic activity that formed one or more of Miranda's coronae or the global rift system."

Regolith is defined as "a region of loose unconsolidated rock and dust that sits atop a layer of bedrock," and the surface material on both the moon and Mars are frequently referred to as regolith as opposed to soil much like Earth. The difference being that soil provides necessary nutrients and minerals for things to grow, whereas regolith can be considered dead soil.

For the study, the researchers analyzed craters, specifically "muted" craters, to determine the thickness of Miranda's surface regolith. These analyses included measuring the crater depth-diameter ratios, crater size-frequency distribution—also known as "crater counting," and the central mound within a specific crater, Alonso Crater. The study's findings determined three potential sources for Miranda's thick regolith, which include giant impact ejecta, plume deposits, and ring deposits from Uranus itself. The researchers state they favor the ring deposit hypothesis due to Miranda's blue color, and its regolith's large spatial extent and large thickness.

"If material from Uranus' rings were the primary source of Miranda's regolith, then that may indicate that Miranda formed out of ring material and/or that Miranda migrated through the rings in its early history," said Dr. Beddingfield. "In these scenarios, Uranus' rings may have been thicker in the past. However, future modeling work is needed to investigate these possibilities further."

Miranda was first discovered on February 16, 1948, by Gerard P. Kuiper at the McDonald Observatory in western Texas, and has only been visited by NASA's Voyager 2 spacecraft in 1986. This up-close encounter revealed a chaotic and intriguing world with craters, valleys, and chasms across its surface, with scientists continuing to debate to this day the processes behind the small moon's interesting features. One such type of feature is known as "coronae," which are large deformations that scientists hypothesize were formed from tectonic activity. So, how can this research help us better understand Miranda's overall surface appearance?

"Because Miranda's thick insulating regolith would reduce heat loss and possibly enhance geologic activity, the regolith may have helped support coronae formation," said Dr. Beddingfield. "The coronae are thought to have formed from upwelling diapirs that broke Miranda's surface. Perhaps the coronae inherited their polygonal shapes when those diapirs formed along pre-existing areas of weakness in the lithosphere, formed by pre-existing faults that make up global rift system. While the existence of Miranda's regolith doesn't tell us much about the specific processes involved in corona formation, it does allow us to get a sense of the relative timing of events and shows that geologic activity likely occurred over long periods of time."

The paper stresses that follow-up studies are required to better understand the potential possibilities other than Uranus ring deposits for Miranda's thick regolith.

"Miranda's regolith could be explained by processes other than ring material accumulation including material deposition due to plume activity in the past or deposition of ejecta from a giant impact," explained Dr. Beddingfield.

"We see evidence for thick plume deposits on Saturn's moon Enceladus, which exhibits ongoing plume activity. Alternatively, if one or more giant impact event events occurred during Miranda's early history, then the resulting ejecta may have formed the observed regolith on Miranda. While we favor the ring material deposition scenario, these two other scenarios are certainly feasible and warrant investigation in future work."

Currently, Voyager 2 remains the only spacecraft to have visited Uranus and its many moons, and there are no scheduled missions to revisit this far out in the solar system.

More information: Chloe B. Beddingfield et al, Miranda's Thick Regolith Indicates a Major Mantling Event from an Unknown Source, The Planetary Science Journal (2022). DOI: 10.3847/PSJ/ac9a4e

Journal information: The Planetary Science Journal 

Provided by Universe Today Study reveals lunar regolith evolution process on Chang'e-4 landing area

Archaeologists uncover oldest known projectile points in the Americas

by Oregon State University

Stone projectile points discovered buried inside and outside of pit features at the Cooper’s Ferry site, Area B. Credit: Loren Davis

Oregon State University archaeologists have uncovered projectile points in Idaho that are thousands of years older than any previously found in the Americas, helping to fill in the history of how early humans crafted and used stone weapons.

The 13 full and fragmentary projectile points, razor sharp and ranging from about half an inch to 2 inches long, are from roughly 15,700 years ago, according to carbon-14 dating. That's about 3,000 years older than the Clovis fluted points found throughout North America, and 2,300 years older than the points previously found at the same Cooper's Ferry site along the Salmon River in present-day Idaho.

The findings were published today in the journal Science Advances.

"From a scientific point of view, these discoveries add very important details about what the archaeological record of the earliest peoples of the Americas looks like," said Loren Davis, an anthropology professor at OSU and head of the group that found the points. "It's one thing to say, 'We think that people were here in the Americas 16,000 years ago'; it's another thing to measure it by finding well-made artifacts they left behind."

Previously, Davis and other researchers working the Cooper's Ferry site had found simple flakes and pieces of bone that indicated human presence about 16,000 years ago. But the discovery of projectile points reveals new insights into the way the first Americans expressed complex thoughts through technology at that time, Davis said.
Credit: Oregon State University

The Salmon River site where the points were found is on traditional Nez Perce land, known to the tribe as the ancient village of Nipéhe. The land is currently held in public ownership by the federal Bureau of Land Management.

The points are revelatory not just in their age, but in their similarity to projectile points found in Hokkaido, Japan, dating to 16,000–20,000 years ago, Davis said. Their presence in Idaho adds more detail to the hypothesis that there are early genetic and cultural connections between the ice age peoples of Northeast Asia and North America.

"The earliest peoples of North America possessed cultural knowledge that they used to survive and thrive over time. Some of this knowledge can be seen in the way people made stone tools, such as the projectile points found at the Cooper's Ferry site," Davis said. "By comparing these points with other sites of the same age and older, we can infer the spatial extents of social networks where this technological knowledge was shared between peoples."

Excavator at work recording artifacts excavated from a pit feature at the Cooper’s Ferry site. Credit: Loren Davis

Overview of the Area B excavations at the Cooper’s Ferry site in 2017. Credit: Loren Davis
Excavator at work recording artifacts excavated from a pit feature at the Cooper’s Ferry site. Credit: Loren Davis

These slender projectile points are characterized by two distinct ends, one sharpened and one stemmed, as well as a symmetrical beveled shape if looked at head-on. They were likely attached to darts, rather than arrows or spears, and despite the small size, they were deadly weapons, Davis said.

"There's an assumption that early projectile points had to be big to kill large game; however, smaller projectile points mounted on darts will penetrate deeply and cause tremendous internal damage," he said. "You can hunt any animal we know about with weapons like these."

These discoveries add to the emerging picture of early human life in the Pacific Northwest, Davis said. "Finding a site where people made pits and stored complete and broken projectile points nearly 16,000 years ago gives us valuable details about the lives of our region's earliest inhabitants."

(A) map showing the location of the Cooper’s Ferry site in the context of Pacific Northwest environments at 16,000 years ago; (B) aerial image (from Google Earth) showing the Cooper’s Ferry excavations; (C) site map showing the locations of excavation Area A and Area B. Credit: Loren Davis

Overview of the Cooper’s Ferry site in the lower Salmon River canyon of western Idaho, USA. Credit: Loren Davis

Overview of pit feature 78 during the process of excavation. Credit: Loren Davis

(A) map showing the location of the Cooper’s Ferry site in the context of Pacific Northwest environments at 16,000 years ago; (B) aerial image (from Google Earth) showing the Cooper’s Ferry excavations; (C) site map showing the locations of excavation Area A and Area B. Credit: Loren Davis

Overview of the Cooper’s Ferry site in the lower Salmon River canyon of western Idaho, USA. Credit: Loren Davis

The newly discovered pits are part of the larger Cooper's Ferry record, where Davis and colleagues have previously reported a 14,200-year-old fire pit and a food-processing area containing the remains of an extinct horse. All told, they found and mapped more than 65,000 items, recording their locations to the millimeter for precise documentation.

The projectile points were uncovered over multiple summers between 2012 and 2017, with work supported by a partnership held between OSU and the BLM. All excavation work has been completed and the site is now covered. The BLM installed interpretive panels and a kiosk at the site to describe the work.

Stratigraphic model of the Cooper’s Ferry site, showing the distribution of cultural features (e.g., fire hearths, pits), radiocarbon and optically stimulated luminescence ages, sediment layers and buried soils as exposed by excavations in Area A and Area B. Credit: Loren Davis

Davis has been studying the Cooper's Ferry site since the 1990s when he was an archaeologist with the BLM. Now, he partners with the BLM to bring undergraduate and graduate students from OSU to work the site in the summer. The team also works closely with the Nez Perce tribe to provide field opportunities for tribal youth and to communicate all findings.


More information: Loren Davis, Dating of a Large Tool Assemblage at the Cooper's Ferry Site (Idaho, USA) Dated ~15,785 cal yr B.P. Extends Age of Stemmed Points in the Americas, Science Advances (2022). DOI: 10.1126/sciadv.ade1248. www.science.org/doi/10.1126/sciadv.ade1248


Journal information: Science Advances


Provided by Oregon State University


Explore furtherNew artifacts suggest people arrived in North America earlier than previously thought

Understanding the “eating just one potato chip is impossible” gene

Scientists reveal genetic mechanism associated with high-calorie food-fueled obesity

Peer-Reviewed Publication

OSAKA METROPOLITAN UNIVERSITY

 

IMAGE: OSAKA METROPOLITAN UNIVERSITY SCIENTISTS HAVE REVEALED THAT THE TRANSCRIPTION COFACTOR GENE CRTC1 MEDIATES THE OBESITY-SUPPRESSING EFFECTS OF MELANOCORTIN-4 RECEPTOR (MC4R) BY REGULATING APPETITE FOR FATS AND OILS, HIGH-FAT DIET METABOLISM, AND BLOOD SUGAR. view more 

CREDIT: SHIGENOBU MATSUMURA, OSAKA METROPOLITAN UNIVERSITY

High-calorie foods—high in fat, oil, and sugar—can taste good but often cause overeating, leading to obesity and major health problems. But what stimulates the brain to cause overeating?

Recently, it has become clear that a gene called CREB-Regulated Transcription Coactivator 1 (CRTC1) is associated with obesity in humans. When CRTC1 is deleted in mice, they become obese, indicating that functioning CRTC1 suppresses obesity. However, since CRTC1 is expressed in all neurons in the brain, the specific neurons responsible for suppressing obesity and the mechanism present in those neurons remained unknown.

To elucidate the mechanism by which CRTC1 suppresses obesity, a research group led by Associate Professor Shigenobu Matsumura from the Graduate School of Human Life and Ecology at Osaka Metropolitan University focused on neurons expressing the melanocortin-4 receptor (MC4R). They hypothesized that CRTC1 expression in MC4R-expressing neurons suppressed obesity because mutations in the MC4R gene are known to cause obesity. Consequently, they created a strain of mice that expresses CRTC1 normally except in MC4R-expressing neurons where it is blocked to examine the effect that losing CRTC1 in those neurons had on obesity and diabetes.

When fed a standard diet, the mice without CRTC1 in MC4R-expressing neurons showed no changes in body weight compared to control mice. However, when the CRTC1-deficient mice were raised on a high-fat diet, they overate, then became significantly more obese than the control mice and developed diabetes.

“This study has revealed the role that the CRTC1 gene plays in the brain, and part of the mechanism that stops us from overeating high-calorie, fatty, and sugary foods,” said Professor Matsumura. “We hope this will lead to a better understanding of what causes people to overeat.”

The research results were published in the FASEB Journal on November 9, 2022.

###

Osaka Metropolitan University is a new public university established by a merger between Osaka City University and Osaka Prefecture University in April 2022. For more science news, see https://www.omu.ac.jp/en/info/research-news/, and follow @OsakaMetUniv_en, or search #OMUScience. 

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JOURNAL

The FASEB Journal

DOI

10.1096/fj.202200617R 

METHOD OF RESEARCH

Experimental study

SUBJECT OF RESEARCH

Animals

ARTICLE TITLE

CRTC1 deficiency, specifically in melanocortin-4 receptor-expressing cells, induces hyperphagia, obesity, and insulin resistance

Massive "marimo" algae balls at risk from deadly winter sunburn

Reduced lake-ice cover due to climate change may further decline of endangered species

Peer-Reviewed Publication

UNIVERSITY OF TOKYO

 

IMAGE: THE ALGA AEGAGROPILA LINNAEI CAN LIVE AS FREE-FLOATING FILAMENTS, GROW ON ROCKS, GROW INTO THE SIGNATURE BALL SHAPE AND FORM FLATTENED BALLS WHEN SQUISHED, DEPENDING ON THEIR ENVIRONMENT. BALL GROWTH IS SLOW AT ABOUT 5 MILLIMETERS PER YEAR AND THEY CAN LIVE FOR CENTURIES. view more 

CREDIT: 2022 YOICHI OYAMA

Climate change could overexpose rare underwater "marimo" algae balls to sunlight, killing them off according to a new study at the University of Tokyo.  Marimo are living fluffy balls of green algae. The world’s largest marimo can be found in Lake Akan in Hokkaido, Japan’s northern main island. Here they are sheltered from too much winter sunlight by a thick layer of ice and snow, but the ice is thinning due to global warming. Researchers found that the algae could survive bright light for up to four hours and would recover if then placed under a moderate light for 30 minutes. However, the algae died when exposed to bright light for six hours or more. The team hopes this discovery will highlight the threat of climate change to this endangered species and the urgent need to protect their habitat.

Some people have pet cats, others pet rocks, but how about pet algae? Marimo are fluffy, squishy green balls of underwater algae which have become popular with tourists, nature enthusiasts and aquarium owners. They range in size from about a pea to a basketball, and form naturally when floating strands of the algae Aegagropila linnaei are bundled together through the gentle rolling motion of lake water. They are only found in a few countries and the largest marimo, found in Lake Akan, can grow up to 30 centimeters in diameter. In Japan, they are so popular that they have their own annual festival, merchandise and even a mascot. However, marimo are an endangered species and globally their numbers are generally in decline.

Marimo rely on nutrients and photosynthesis to survive. Their decline is usually attributed to human intervention altering or polluting the freshwater lakes in which they live. However, there has not been much research into the effect of changing access to sunlight. “We know that marimo can survive bright sunlight in warm summer waters, but the photosynthetic properties in marimo at low winter temperatures have not been studied, so we were fascinated by this point,” said Project Assistant Professor Masaru Kono from the Graduate School of Science at the University of Tokyo. “We wanted to find out whether Marimo could tolerate it and how they respond to a low-temperature, high light-intensity environment.”

Kono and team visited Lake Akan’s Churui Bay in winter to measure the temperature and light intensity underwater, both with and without ice cover. First, they bored a small hole in the ice 80 meters offshore and then carved a large 2.5 meter-by-2.5 meter square to take readings from. They also carefully collected several marimo balls about the size of a shot put (10-15 cm) by hand. Back in Tokyo, the team recreated the environmental conditions using trays of ice made with an icemaker and white LED lamps. Algae strands were removed from the marimo balls and tested for their normal photosynthetic ability. They were then placed in containers in the ice under the artificial light, which was adjusted to shine at different intensities for different periods of time.

“We demonstrated a new finding that damaged cells in marimo can repair themselves even after exposure to simulated strong daylight for up to four hours at cold temperatures (2-4 degrees Celsius), when followed by moderate light exposure for just 30 minutes. This moderate light had a restorative effect which did not occur in the dark. However, when exposed to strong daylight for six hours or more, certain cells involved in photosynthesis were damaged and the algae died, even after being treated with moderate light,” explained Kono. “These results suggest that photoinhibition (the inability to photosynthesize due to cell damage) would be a serious threat to marimo in Lake Akan, which receives more than 10 hours of sunlight a day in winter, if global warming proceeds and ice cover recedes.”

Next, the team want to find out what would happen to whole marimo balls and whether the outcome would be the same as with the smaller threads. “In the present study, we used dissected filamentous cells, so we did not consider the effects of the structure of the spherical marimo and how it might protect against exposure to bright light. However, if damage to the surface cells increases under longer exposure to the direct sunlight, in an extreme case, this may affect the maintenance of their round bodies and lead to the disappearance of giant marimo. So, we need to constantly monitor the conditions at Lake Akan in the future” said Kono.

Kono hopes this research will help both local and national governments to understand the urgent need to protect Japan’s unique marimo and their habitat. “We also hope this will be an opportunity for all people to think seriously about the effects of global warming,” he said.

Temperatures underwater are kept relatively stable and warm at around 1-4 degrees Celsius, thanks to the blanket of ice and snow. Above ground, however, they vary from minus 18 degrees to 1 degree Celsius.

CREDIT

2022 Asami Fujita

A researcher takes samples of algae filaments from the marimo ball. The ball is made up of green algae throughout and doesn’t have a different material at its core.

Too much sun in cold temperatures cannot be processed and instead causes harmful, reactive chemicals to form. This damages the marimo’s ability to photosynthesize and repair itself.

CREDIT

2022 Akina Obara

Paper Title:

Akina Obara, Mari Ogawa, Yoichi Oyama, Yoshihiro Suzuki, Masaru Kono. Effects of high irradiance and low water-temperature on photoinhibition and repair of photosystems in Marimo (Aegagropila linnaei) in Lake Akan, Japan. Int. J. Mol. Sci. 2023, 24(1), 60; https://doi.org/10.3390/ijms24010060

Funding: 

This work was supported by JSPS KAKENHI (21K15118).

Useful Links:

Graduate School of Science: https://www.s.u-tokyo.ac.jp/en/info/6799/

Research contact:

Project Assistant Professor Masaru Kono

Department of Biological Sciences,

Graduate School of Science, The University of Tokyo,

7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan

Email: konom07@bs.s.u-tokyo.ac.jp

Press contact:
Mrs. Nicola Burghall
Public Relations Group, The University of Tokyo,
7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8654, Japan
press-releases.adm@gs.mail.u-tokyo.ac.jp

About the University of Tokyo
The University of Tokyo is Japan's leading university and one of the world's top research universities. The vast research output of some 6,000 researchers is published in the world's top journals across the arts and sciences. Our vibrant student body of around 15,000 undergraduate and 15,000 graduate students includes over 4,000 international students. Find out more at www.u-tokyo.ac.jp/en/ or follow us on Twitter at @UTokyo_News_en.

 

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JOURNAL

International Journal of Molecular Sciences

DOI

10.3390/ijms24010060 

METHOD OF RESEARCH

Experimental study

SUBJECT OF RESEARCH

Not applicable

ARTICLE TITLE

Effects of high irradiance and low water-temperature on photoinhibition and repair of photosystems in Marimo (Aegagropila linnaei) in Lake Akan, Japan.

ARTICLE PUBLICATION DATE

21-Dec-2022

Lost fish find their way, thanks to their ‘ancient brain’

Multiregional hindbrain circuit enables animals to get back on track after falling off course

Peer-Reviewed Publication

HOWARD HUGHES MEDICAL INSTITUTE

 

VIDEO: THIS VIDEO SHOWS A VIRTUAL REALITY ENVIRONMENT FOR LARVAL ZEBRAFISH. THE FISH TRAVERSES A 2D ENVIRONMENT IN THE PRESENCE OF A SIMULATED WATER FLOW. view more 

CREDIT: MISHA AHRENS

A zebrafish swims toward its intended target, but strong currents push it off course. Nevertheless, the tiny fish swims back to its original location, determined to finish its journey.

How do animals know where they are in their environment, and how does this determine their subsequent choices? Scientists at HHMI’s Janelia Research Campus discovered that the hindbrain – an evolutionarily conserved or “ancient” region in the back of the brain – helps animals compute their location and use that information to figure out where they need to go next.

The new research, being published in the journal Cell Dec. 22, uncovers new functions for parts of the “ancient brain,” findings that could apply to other vertebrates.

Whole-brain imaging reveals new networks

To figure out how animals understand their position in the environment, researchers, led by En Yang, a postdoc in the Ahrens Lab, put tiny translucent zebrafish, barely half a centimeter in length, in a virtual reality environment that simulates water currents. When the current shifts unexpectedly, the fish are initially pushed off course; however, they are able to correct for that movement and get back to where they started.

While a zebrafish is swimming in the virtual reality environment, the researchers use a whole-brain imaging technique developed at Janelia to measure what is happening in the fish’s brain. This technique allows the scientists to search the entire brain to see which circuits are activated during their course-correcting behavior and disentangle the individual components involved.

The researchers expected to see activation in the forebrain – where the hippocampus, which contains a “cognitive map” of an animal’s environment, is located. To their surprise, they saw activation in several regions of the medulla, where information about the animal’s location was being transmitted from a newly identified circuit via a hindbrain structure called the inferior olive to the motor circuits in the cerebellum that enable the fish to move. When these pathways were blocked, the fish was unable to navigate back to its original location.

These findings suggest that areas of the brainstem remember a zebrafish’s original location and generate an error signal based on its current and past locations. This information is relayed to the cerebellum, allowing the fish to swim back to its starting point. This research reveals a new function for the inferior olive and the cerebellum, which were known to be involved in actions like reaching and locomotion, but not this type of navigation.

“We found that the fish is trying to calculate the difference between its current location and its preferred location and uses this difference to generate an error signal,” says Yang, the first author of the new study. “The brain sends that error signal to its motor control centers so the fish can correct after being moved by flow unintentionally, even many seconds later.”  

A new multiregional hindbrain circuit

It is still unclear whether these same networks are involved in similar behavior in other animals. But the researchers hope labs studying mammals will now start looking at the hindbrain for homologous circuits for navigation.

This hindbrain network could also be the basis of other navigational skills, such as when a fish swims to a specific place for shelter, say the researchers.

“This is a very unknown circuit for this form of navigation that we think might underlie higher order hippocampal circuits for exploration and landmark-based navigation,” says Janelia Senior Group Leader Misha Ahrens.  

Zebrafish whole-brain imaging [VIDEO] | EurekAlert! Science News Releases

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JOURNAL

Cell

DOI

10.1016/j.cell.2022.11.022 

ARTICLE TITLE

A brainstem integrator for self-location memory and positional homeostasis in zebrafish

ARTICLE PUBLICATION DATE

22-Dec-2022

Microplastics deposited on the seafloor triple in 20 years

Peer-Reviewed Publication

UNIVERSITAT AUTONOMA DE BARCELONA

 

IMAGE: RESEARCHER LAURA SIMON-SÁNCHEZ DURING ONE OF THE SAMPLE COLLECTION CAMPAIGNS view more 

CREDIT: (AUTHOR: LENA HEINS).

The total amount of microplastics deposited on the bottom of oceans has tripled in the past two decades with a progression that corresponds to the type and volume of consumption of plastic products by society. This is the main conclusion of a study developed by the Institute of Environmental Science and Technology of the Universitat Autònoma de Barcelona (ICTA-UAB) and the Department of the Built Environment of Aalborg University (AAU-BUILD), which provides the first high-resolution reconstruction of microplastic pollution from sediments obtained in the northwestern Mediterranean Sea.

Despite the seafloor being considered the final sink for microplastics floating on the sea surface, the historical evolution of this pollution source in the sediment compartment, and particularly the sequestration and burial rate of smaller microplastics on the ocean floor, is unknown.

This new study, published in the journal Environmental Science and Technology (ES&T), shows that microplastics are retained unaltered in marine sediments, and that the microplastic mass sequestered in the seafloor mimics the global plastic production from 1965 to 2016. "Specifically, the results show that, since 2000, the amount of plastic particles deposited on the seafloor has tripled and that, far from decreasing, the accumulation has not stopped growing mimicking the production and global use of these materials," explains ICTA-UAB researcher Laura Simon-Sánchez.

Researchers explains that the sediments analysed have remained unaltered on the seafloor since they were deposited decades ago. "This has allowed us to see how, since the 1980s, but especially in the past two decades, the accumulation of polyethylene and polypropylene particles from packaging, bottles and food films has increased, as well as polyester from synthetic fibres in clothing fabrics," explains Michael Grelaud, ICTA-UAB researcher. The amount of these three types of particles reaches 1.5mg per kilogram of sediment collected, with polypropylene being the most abundant, followed by polyethylene and polyester. Despite awareness campaigns on the need to reduce single-use plastic, data from annual marine sediment records show that we are still far from achieving this. Policies at the global level in this regard could contribute to improving this serious problem.

Although smaller microplastics are very abundant in the environment, constraints in analytical methods have limited robust evidence on the levels of small microplastics in previous studies targeting marine sediment. In this study they were characterised by applying state-of-the-art imaging to quantify particles down to 11 µm in size.

The degradation status of the buried particles was investigated, and it was found that, once trapped in the seafloor, they no longer degrade, either due to lack of erosion, oxygen, or light. "The process of fragmentation takes place mostly in the beach sediments, on the sea surface or in the water column. Once deposited, degradation is minimal, so plastics from the 1960s remain on the seabed, leaving the signature of human pollution there," says Patrizia Ziveri, ICREA professor at ICTA-UAB.

The investigated sediment core was collected in November 2019, on board the oceanographic vessel Sarmiento de Gamboa, in an expedition that went from Barcelona to the coast of the Ebro Delta, in Tarragona, Spain. The research group selected the western Mediterranean Sea as a study area, in particular the Ebro Delta, because rivers are recognized as hotspots for several pollutants, including microplastics. In addition, the influx of sediment from the Ebro River provides higher sedimentation rates than in the open ocean.

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JOURNAL

Environmental Science & Technology

DOI

10.1021/acs.est.2c04264 

METHOD OF RESEARCH

Experimental study

SUBJECT OF RESEARCH

Not applicable

ARTICLE TITLE

Microplastic preservation in a coastal sedimentary record

Antarctic post office: A home for Christmas among the penguins

Sara Monetta - BBC News
Fri, December 23, 2022 

A group of four British women recently arrived on a remote Antarctic island to look after its population of passing tourists and penguins. As they prepare for Christmas at the bottom of the world, they tell BBC News how they're settling into their new home.

When Clare Ballantyne reached the place she was going to call home for the next five months, she found it buried under metres of snow. "We warmed up very quickly by digging a lot," she says with a chuckle.

Clare was chosen along with three other women - Mairi Hilton, Lucy Bruzzone and Natalie Corbett - to look after the remote harbour of Port Lockroy, some 911 miles south of the Falkland Islands.

They beat thousands of other applicants to run the base through the Antarctic summer for the UK Antarctic Heritage Trust.

Once a British military base and research station, nowadays it consists of a post office, a museum and a gift shop. The team plays host to passing cruise ships and keeps an eye on the island's population of around 1,000 gentoo penguins.

Four women to run world's most remote post office


Job hunt for team to run Antarctica post office


Navy digs out snowed-in Antarctic post office

Speaking to the women is extremely difficult, but Clare and Mairi - the team's wildlife monitor - have managed to tell me about their experience over a patchy satellite phone line.

"We were digging out access to the buildings, making sure that the solar panels were unlocked from snow and they were all working, that we had sufficient water and gas, and made sure that we were safe to stay on the island," Clare says.

The Royal Navy had been called in to help the team and fix the roof of the museum, which had been damaged under the weight of the snow. Clare recalls the moment the sailors left and the team remained on the island on their own, surrounded only by penguins and icebergs silently floating in the channel. "It was just incredible," she says.

(L-R): Lucy Bruzzone, Mairi Hilton, Clare Ballantyne and Natalie Corbett beat 4,000 other applicants to run Port Lockroy

Clare's job, as the postmaster, is to mail postcards sent by visiting tourists to countries all around the world. "The mail I send from here takes about four weeks to reach the UK," she tells me. "I'm really excited that I'm at the start of the journey where the mail goes off."

By the time I speak with Clare and Mairi, they have already spent several weeks in Port Lockroy and the team has settled into a well-oiled routine. "We get up at 7am," Mairi says. "We have breakfast, and go down to dig out the landing site where the guests arrive.

"We have one cruise ship in the morning. Tourists come and visit the museum, the shop and see the penguins. Then we have lunch and a second group of tourists arrive in the afternoon until about 6pm. In the evening we have dinner, we monitor the penguins and we do any other task that's needed," she adds.

Port Lockroy is the most popular tourist destination in Antarctica, with around 18,000 visitors each year. But it's a symbiotic relationship: the team relies heavily on assistance given by passing ships.

"We don't have any running water, so we get our drinking water from cruise ships," Mairi says, "and we also get showers there."

"We get fresh fruit and vegetables and bread from the ships that come to visit. The crews take very good care of us," Clare adds.

Since there's no internet connection in Port Lockroy, the main way for the team to be in touch with their families and keep up with events in the outside world is by using the wi-fi on the ships. And although the team has received advanced first-aid training, should they need to see a doctor, they can find one on board a visiting vessel.

The museum at the end of the world reopens at last

Inside the floating polar research laboratory

But it's not always that straightforward. They say the unpredictability of Antarctic weather means that the team could suddenly remain isolated for days.

"You never know what the day is going to bring," Clare says. "You don't know if you're going to have a ship in the morning, if you're going to have a storm. You have to be very flexible."

Still, despite the challenges, they are still in awe of their surroundings. "Every morning when you walk up the snowy steps of the building, the mountains, and the icebergs in the channel that surrounds us, it's just beautiful and seeing the penguins puts a smile on your face," Clare says.

I ask them what it's like to be the only four humans among hundreds of resident penguins. "They're not as noisy as I expected," Mairi says. "They're very good neighbours and they're really funny to watch."

The team's main task when it comes to monitoring the wildlife is to count the eggs that are usually laid at this time of year. But Mairi says the changing weather conditions seem to have delayed the breeding season.

"There's lots of snow and we also don't have any fast sea ice in the bay, which is unusual. The penguins' eggs won't survive if they're laid in snow, so if we keep getting these warmer, milder winters, that's not going to be good for our penguins here."

Clare and Mairi say they haven't had much free time yet, but they're trying to savour every single moment they spend on the island. So I ask them if they're planning anything special for their very unusual Christmas.

"We are taking the day off," Mairi says. "Some of us are going to do a Christmas pudding, some mince pies and gingerbread biscuits. We'll just relax and have a Christmas dinner and do lots of things you'd usually do at home - but in Antarctica."

Current Antarctic conservation efforts are insufficient to avoid biodiversity declines

Ten key management strategies could benefit up to 84% of plants and animals

Peer-Reviewed Publication

PLOS

 

IMAGE: A LONE EMPEROR PENGUIN FLOATING ON AN ICEBERG FAR FROM ITS COLONY IN THE ANTARCTIC PENINSULA view more 

CREDIT: JASMINE LEE (CC-BY 4.0, HTTPS://CREATIVECOMMONS.ORG/LICENSES/BY/4.0/)

Existing conservation efforts are insufficient to protect Antarctic ecosystems, and population declines are likely for 65% of the continent’s plants and wildlife by the year 2100, according to a study by Jasmine Rachael Lee at the University of Queensland, Australia, and colleagues, publishing December 22nd in the open access journal PLOS Biology. Implementing ten key threat management strategies — at an annual cost of 23 million US dollars — would benefit up to 84% of terrestrial bird, mammal, and plant groups.

To better understand which species are most vulnerable and identify the most cost-effective actions, researchers combined expert assessments with scientific data to evaluate threats and conservation strategies for Antarctica. They asked 29 experts to define possible management strategies, estimate their cost and feasibility, and assess the potential benefit to different species between now and 2100.

Climate change was identified as the most serious threat to Antarctic biodiversity and influencing global policy to limit warming was the most beneficial conservation strategy. Under current management strategies and more than 2 degrees Celsius of warming, 65% of land plants and animals will decline by 2100. Emperor penguins (Aptenodytes forsteri) were identified as the most vulnerable, followed by other sea birds and soil nematode worms. However, regional management strategies could benefit up to 74% of plants and animals at an estimated cost of 1.92 billion US dollars over the next 83 years, equating to 0.004% of global GDP in 2019. The regional management strategies identified as offering the greatest return on investment were minimizing the impacts of human activities, improving the planning and management of new infrastructure projects, and improving transport management.

As Antarctica faces increasing pressure from climate change and human activities, a combination of regional and global conservation efforts is needed to preserve Antarctic biodiversity and ecosystem services for future generations, the authors say.

Lee adds, “What this work shows is that climate change is the greatest threat to Antarctic species and what we need is global mitigation efforts to save them. This will not only help to secure their future, but also our own.”

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In your coverage, please use this URL to provide access to the freely available paper in PLOS Biology: http://journals.plos.org/plosbiology/article?id=10.1371/journal.pbio.3001921

#####

In your coverage, please use this URL to provide access to the freely available paper in PLOS Biology: http://journals.plos.org/plosbiology/article?id=10.1371/journal.pbio.3001921

Citation: Lee JR, Terauds A, Carwardine J, Shaw JD, Fuller RA, Possingham HP, et al. (2022) Threat management priorities for conserving Antarctic biodiversity. PLoS Biol 20(12): e3001921. https://doi.org/10.1371/journal.pbio.3001921

Author Countries: Australia, United Kingdom, United States, South Africa, New Zealand, France, Denmark, Norway, Switzerland, Belgium

Funding: see manuscript

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JOURNAL

PLoS Biology

DOI

10.1371/journal.pbio.3001921 

SUBJECT OF RESEARCH

Not applicable

COI STATEMENT

Competing interests: The authors have declared that no competing interests exist.

Title 42 border rules confound Washington, migrants alike




Senate DemocratsSen. Dick Durbin, D-Ill., speaks during a news conference with members of Senate Democratic leadership, Tuesday, Dec. 6, 2022, on Capitol Hill in Washington. in Washington. 

(AP Photo/Mariam Zuhaib)

COLLEEN LONG
Fri, December 23, 2022 at 9:51 AM MST·6 min read


WASHINGTON (AP) — The drawn-out saga of Title 42, the set of emergency powers that allows border officials to quickly turn away migrants, has been chaotic at the U.S.-Mexico border. In Washington, it hasn't unfolded much better.

The Supreme Court is weighing whether to keep the powers in place following months of legal battles brought on by Republican-led states after President Joe Biden's administration moved to end the Trump-era policy, which was set to lapse this week until the court agreed to take it up.

The administration has yet to lay out any systemic changes to manage an expected surge of migrants if the restrictions end. And a bipartisan immigration bill in Congress has been buried just as Republicans are set to take control of the House.

In short, America is right back where it has been. A divided nation is unable to agree on what a longer-term fix to the immigration system should look like. Basic questions — for example, should more immigrants be allowed in, or fewer? — are unanswered. Meantime the asylum system continues to strain under increasing numbers of migrants.

The Biden administration has been reluctant to take hardline measures that would resemble those of his predecessor. That's resulted in a barrage of criticism from Republicans who are using Title 42 to hammer the president as ineffective on border security. The rules were introduced as an emergency health measure to prevent the spread of COVID-19.

“The Democrats have lost the messaging war on this," said Charles Foster, a longtime immigration attorney in Texas who served as an immigration policy adviser to Republican George W. Bush but now considers himself independent. "The tragedy is, Democrats more than anyone should focus on this issue, because unless and until it can be fixed, and the perception changes, we’ll get nothing ever through Congress."

Anyone who comes to the U.S. has the right to ask for asylum, but laws are narrow on who actually gets it. Under Biden, migrants arriving at the border are often let into the country and allowed to work while their cases progress. That process takes years because of a 2-million-case backlog in the immigration court system that was exacerbated by Trump-era rules.

Title 42 allows border officials to deny people the right to seek asylum, and they have done so 2.5 million times since March 2020. The emergency health authority has been applied disproportionately to those from countries that Mexico agreed to take back: Guatemala, Honduras, El Salvador and more recently Venezuela, in addition to Mexico.

“There is not going to be a good moment, politically speaking,” to end the restrictions, said Jorge Loweree of the American Immigration Council. The administration should have been preparing all along to create a better system for asylum seekers," Loweree said.

“It has allowed the other side to weaponize this issue. And the longer it remains in place, the longer the weapon will remain effective.”

The authority was first invoked at the height of the COVID-19 pandemic by President Donald Trump, whose immigration policies were aimed at keeping out as many migrants as possible. He also drastically reduced the number of refugees allowed into the country, added restrictions to the asylum process that clogged the system and kept migrants in detention, and reduced legal immigration pathways.

Biden has been working to expand legal immigration and has undone some of the most restrictive Trump policies. But the administration kept the policy in place until this spring, and even expanded its use after announcing it would end.

Republican say there will be even more chaos if it's lifted. But even with Title 42 in place, border officials have been encountering more migrants than ever before. In the budget year that ended Sept. 30, migrants were stopped 2.38 million times, up 37% from 1.73 million times the year before.

“I don’t know why it’s taking them so long to get serious about deterrence,” Republican Sen. Shelley Moore Capito of West Virginia said of the Biden administration. Capito is an incoming member of the Senate Republican leadership and the top GOP senator on the committee that oversees money for Homeland Security, the federal agency that manages border security.

Border officials have braced for an expected increase, and migrants who have arrived are unsure of how asylum processes will work when the policy ends. Homeland Security officials have reported faster processing for migrants in custody on the border, more temporary detention tents, staffing increases and more criminal prosecutions of smugglers.

They say progress has been made on a plan announced in April but large-scale changes are needed. Meanwhile, the Senate's Republican leadership killed a bipartisan immigration bill that would have addressed some of these issues.

The split isn't just inside Congress. One in 3 U.S. adults believes an effort is underway to replace native-born Americans with immigrants for electoral gains, according to an AP-NORC survey.

Biden and his aides have said they are working to divert migrants coming out of Central America and helping provide aid to poorer nations that are bleeding people headed for the U.S. But the president is limited without action from Congress.

White House press secretary Karine Jean-Pierre said the administration is surging assistance to the border and will continue to do so. But “the removal of Title 42 does not mean the border is open,” she said. "Anyone who suggests otherwise is simply doing the work of these smugglers who again are spreading misinformation, which is very dangerous.”

A year-long appropriations bill passed the Senate on Thursday that would give the Border Patrol 17% more money, as well as 13% more for the Justice Department to develop an electronic case management system for immigration courts.

But Citizenship and Immigration Services, central in the asylum process, only got one third of what Biden had proposed to speed up the system.

Democrats, for their part, say they want policies that reflect America's reputation as a haven for those fleeing persecution. But they can’t agree on what that looks like.

Sen. Dick Durbin, D-Ill., has been working on the issue for 20 years. This week, he stood on the Senate floor, sounding dejected as he talked about how Congress couldn't push through reform.

“It is a humanitarian and security nightmare that is only getting worse,” he said. “We're being flooded at the border by people who want to be in the United States, safely in the United States.”

Why, he asked, can't Washington figure out a better way?

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Associated Press Writer Seung Min Kim contributed to this report.