. Scientific Frontline: Earth Science
Showing posts with label Earth Science. Show all posts
Showing posts with label Earth Science. Show all posts

Thursday, May 18, 2023

Past climate change to blame for Antarctica’s giant underwater landslides

Dr Jenny Gales (right) and Professor Rob McKay examine the half-section of a core recovered from the Antarctic seabed
Photo Credit: Justin Dodd

Scientists have discovered the cause of giant underwater landslides in Antarctica which they believe could have generated tsunami waves that stretched across the Southern Ocean.

An international team of researchers, led by Dr Jenny Gales from the University of Plymouth, uncovered layers of weak, fossilized and biologically-rich sediments hundreds of meters beneath the seafloor.

These formed beneath extensive areas of underwater landslides, many of which cut more than 100 meters into the seabed.

Writing in Nature Communications, the scientists say these weak layers – made up of historic biological material – made the area susceptible to failure in the face of earthquakes and other seismic activity.

They also highlight that the layers formed at a time when temperatures in Antarctica were up to 3°C warmer than they are today, when sea levels were higher and ice sheets much smaller than at present.

Wednesday, May 17, 2023

Genetic research offers new perspective on the early evolution of animals

Some representatives of comb jellies - (a) Beroe ovata, (b) Euplokamis sp., (c) Nepheloctena sp., (d) Bathocyroe fosteri, (e) Mnemiopsis leidyi, and (f) Ocyropsis sp.
Image Credits: a, b, e, f: Joseph F. Ryan; c: R. Griswold, National Oceanic and Atmospheric Administration; d: Marsh Youngbluth, National Oceanic and Atmospheric Administration.

Mapping gene linkages provides clear-cut evidence for comb jellies as sibling group to all other animals

A study published by University of Vienna and MBARI researchers and their collaborators today in Nature provides new insights into one of the earliest points in animal evolution that happened more than 700 million years ago.

For more than a century, scientists have been working to understand the pivotal moment when an ancient organism gave rise to the diverse array of animals in the world today. As technology and science have advanced, scientists have investigated two alternative hypotheses for which animals—sponges or comb jellies, also known as ctenophores—were most distantly related to all other animals. Identifying this outlier—known as the sibling group—has long eluded scientists.

In the new study, a team of researchers from MBARI, the University of Vienna, the University of California, Berkeley, and the University of California, Santa Cruz, mapped sets of genes that are always found together on a single chromosome, in everything from humans and hamsters to crabs and corals, to provide clear evidence that comb jellies are the sibling group to all other animals. Understanding the relationships among animals will help shape our thinking about how key features of animal anatomy, such as the nervous system or digestive tract, have evolved over time.

Scales or feathers? It all comes down to a few genes

From left to right: Rory Cooper, a post-doctoral researcher in Michel Milinkovitch’s laboratory, and Michel Milinkovitch, professor in the Department of Genetics and Evolution at the Faculty of Science of the UNIGE. 
Photo Credit: UNIGE

Scales, spines, feathers and hair are examples of vertebrate skin appendages, which constitute a remarkably diverse group of micro-organs. Despite their natural multitude of forms, these appendages share early developmental processes at the embryonic stage. Two researchers from the University of Geneva (UNIGE) have discovered how to permanently transform the scales that normally cover the feet of chickens into feathers, by specifically modifying the expression of certain genes. These results, published in the journal Science Advances, open new perspectives for studying mechanisms that have enabled radical evolutionary transitions in form among species.

The skin of terrestrial vertebrates is adorned with diverse keratinized appendages, such as hair, feathers, and scales. Despite the diversity of forms within and among species, the embryonic development of skin appendages typically begins in a very similar way. Indeed, all of these structures develop from cells that produce a localized thickening on the skin surface and express particular genes. One of these genes, called Sonic hedgehog (Shh), controls a signaling pathway - a communication system that allows the transmission of messages within and between cells. Shh signaling is involved in the development of diverse structures, including the neural tube, limb buds and skin appendages.

A better way to study ocean currents

Computer scientists at MIT joined forces with oceanographers to develop a machine-learning model that incorporates knowledge from fluid dynamics to generate more accurate predictions about the velocities of ocean currents. This figure shows drifting buoy trajectories in the Gulf of Mexico superimposed on surface currents. The red dots mark the buoys’ positions on March 9, 2016, and the tails are 14 days long.
Image Credits: Edward Ryan and Tamay Özgökmen from the University of Miami.

A new machine-learning model makes more accurate predictions about ocean currents, which could help with tracking plastic pollution and oil spills, and aid in search and rescue.

To study ocean currents, scientists release GPS-tagged buoys in the ocean and record their velocities to reconstruct the currents that transport them. These buoy data are also used to identify “divergences,” which are areas where water rises up from below the surface or sinks beneath it.

By accurately predicting currents and pinpointing divergences, scientists can more precisely forecast the weather, approximate how oil will spread after a spill, or measure energy transfer in the ocean. A new model that incorporates machine learning makes more accurate predictions than conventional models do, a new study reports.

A multidisciplinary research team including computer scientists at MIT and oceanographers has found that a standard statistical model typically used on buoy data can struggle to accurately reconstruct currents or identify divergences because it makes unrealistic assumptions about the behavior of water.

The researchers developed a new model that incorporates knowledge from fluid dynamics to better reflect the physics at work in ocean currents. They show that their method, which only requires a small amount of additional computational expense, is more accurate at predicting currents and identifying divergences than the traditional model.

Fauna return rapidly in planted eelgrass meadows

Comparison between newly planted eelgrass, to the left and eelgrass that is 15 months old, right.
Photo Credit: Eduardo Infantes

A study of eelgrass meadows planted by researchers from the University of Gothenburg shows that fauna return rapidly once the eelgrass has started to grow. Already after the second summer, the biodiversity in the planted meadow was almost the same as in old established eelgrass meadows.

Eelgrass meadows have declined heavily in southern Bohus county in recent decades and in many places have disappeared altogether. Researchers at the University of Gothenburg have been working on the restoration of eelgrass meadows for twelve years. These meadows are important for biodiversity, as the eelgrass serves as habitat or nursery for young cod, crabs and shrimps for example.  

In a new study, the researchers have evaluated how rapidly replanted eelgrass gets populated by various invertebrates. The study has been going on for over two years in a bay near Gåsö island just west of Skaftö in Bohus county, and the findings are very positive. The researchers counted the abundance of invertebrates that live or burrow in bottom sediments or on the surface of bottom sediments.

Tuesday, May 16, 2023

Warm Ice Age” Changed Climate Cycles

The “Joides Resolution” research vessel – in the port of Lisbon – has been used since 1985 as part of the International Ocean Discovery Program for scientific drilling. The drill cores used in the current “warm ice age” study were taken during an expedition in the Gulf of Cádiz and off of southern Portugal. 
Photo Credit:  André Bahr

Earth scientists identify pivotal step in the Earth’s later climate development

Approximately 700,000 years ago, a “warm ice age” permanently changed the climate cycles on Earth. Contemporaneous with this exceptionally warm and moist period, the polar glaciers greatly expanded. A European research team including Earth scientists from Heidelberg University used recently acquired geological data in combination with computer simulations to identify this seemingly paradoxical connection. According to the researchers, this profound change in the Earth’s climate was responsible for the change in the climate cycles, thus representing a critical step in the later climate evolution of our planet.

South Africa’s desert-like interior may have been more inviting to our human ancestors

Illustration Credit: Scientific Frontline

Lining the Cape of South Africa and its southern coast are long chains of caves that nearly 200,000 years ago were surrounded by a lush landscape and plentiful food.

During a glacial phase that lasted between 195,000 to 123,000 years ago, these caves served as refuge to a group of humans that some researchers think were the only people to survive this ice age, called Marine Isotope Stage Six, or MIS6. And in this coastal region, a lot of archaeological research has taken place. Of less interest to archaeologists has been the interior of South Africa, which was thought to be an uninhabited, inhospitable place during at least two waves of ice ages, MIS3 and 2.

Now, a study has shown that the region might have been more fertile and temperate during these two glacial periods than previously thought, and that the region likely played host to human populations living around a series of paleolakes. The study, led by University of Michigan archaeologist Brian Stewart, provides a more comprehensive timeline of the age and stages of these lakes, and shows human fingerprints across the region. The research, funded by the National Geographic Society, is published in the journal PNAS.

Monday, May 15, 2023

Sea anemone’s sweet efforts help reef ecosystems flourish

KAUST researchers have discovered how corals can thrive in nutrient-depleted oceans. Their study shows how sea anemones are able to recycle the essential nutrient Nitrogen.
Photo Credit: Morgan Bennett-Smith / King Abdullah University of Science and Technology

Tropical oceans are known for being low in nutrients, yet they support incredibly diverse and thriving reef ecosystems created by symbiotic cnidarians such as corals and anemones. This intriguing contradiction, referred to as the Darwin Paradox, has fascinated scientists ever since Charles Darwin first described it in 1842.

A group of researchers from KAUST conducted a study on sea anemones called Aiptasia. They found out that Aiptasia uses the sugar it gets from its partners to recycle waste in its body and survive in places where there are not many nutrients.

According to Guoxin Cui, a research scientist who worked on the project with Manuel Aranda, many studies in the past have tried to figure out where the limited nutrients in the ocean come from, especially nitrogen which is rare.

Guoxin Cui explains that some studies about coral have suggested that the partnership between coral and algae creates areas with lots of nutrients. But until now, researchers didn't fully understand how these organisms were able to create such large ecosystems.

Friday, May 12, 2023

Scientists Discover Fire Records Embedded Within Sand Dunes

An illustration showing how charcoal layers accumulate in dune foot-slope deposits.
Full size image
Image Credit: Nicholas Patton / Desert Research Institute

Knowing how the frequency and intensity of wildfires has changed over time offers scientists a glimpse into Earth’s past landscapes, as well as an understanding of future climate change impacts. To reconstruct fire records, researchers rely heavily on sediment records from lake beds, but this means that fire histories from arid regions are often overlooked. Now, a new study shows that sand dunes can serve as repositories of fire history and aid in expanding scientific understanding of fire regimes around the world.

Published May 11 in Quaternary Research, the study is the first to examine sedimentary records preserved in foot-slope deposits of sand dunes. The research team, led by Nicholas Patton, Ph.D., a postdoctoral researcher now at DRI, studied four sand dunes at the Cooloola Sand Mass in Australia. Australia is one of the world’s most fire-prone landscapes, with a long history of both natural and cultural burning, and vast expanses without lakes or ponds to gather sedimentary records from. The researchers aimed to prove that these sand dune deposits could be used to reconstruct reliable, multi-millennial fire histories. These previously unrecognized archives could potentially be used in arid regions around the world to fill knowledge gaps in places where fire shapes the landscape.

Thursday, May 11, 2023

Australian fruit holds the key to citrus disease resistance

Upuli Nakandala and Prof Robert Henry with a native Finger lime.
Photo Credit: Megan Pope

A comprehensive map of the genome of a native lime species that is resistant to a devastating citrus disease could be the key to preventing that disease entering Australia.

Researchers from The University of Queensland have sequenced the genome of the Australian round lime, also known as the Gympie lime, and are now looking at five other native citrus species including the finger lime.

PhD candidate Upuli Nakandala said the work aimed to identify a gene which provides resistance to Huanglongbing (HLB), also known as 'citrus greening', that could be incorporated into commercial citrus varieties.

“The species citrus australis is recognized as HLB-resistant so we put it first on our list,” Ms. Nakandala said.

Tuesday, May 9, 2023

Earth’s first animals had particular taste in real estate

Obamus coronatus.
Photo Credit: Mary Droser/University of California, Riverside

Even without body parts that allowed for movement, new research shows — for the first time — that some of Earth’s earliest animals managed to be picky about where they lived.

These creatures from the Ediacaran Period, roughly 550 million years ago, are strangely shaped soft-bodied animals that lived in the sea. Researchers have long considered them enigmatic. 

“It’s not like studying dinosaurs, which are related to birds that we can observe today,” said Phillip C. Boan, UC Riverside paleontology graduate student and lead author of the new study. “With these animals, because they have no modern descendants, we’re still working out basic questions about how they lived, such as how they reproduced and what they ate.”

For this particular research project, the researchers focused on understanding where in the sea the animals spent their lives. 

The ancient sea was also a largely foreign place compared to today’s marine environments. It was dominated by a mat on the sea floor composed of bacteria and layers of other organic materials. In addition, predatory creatures were uncommon.

Beetles and their biodiversity in dead wood

The red dots on the map of Europe show the locations where the biodiversity of deadwood beetles was studied in relation to the available energy.
Illustration Credit: Peter Kriegel / Universität Würzburg

Which energy type promotes the biodiversity of beetles living in dead wood in the forest? That depends entirely on where the beetles are in the food chain.

Energy is the key to life. For decades, scientists have been trying to decipher the connection between available energy and biodiversity in ecosystems.

In the process, clear correlations have emerged. For example, ecosystems with higher energy input, for example due to stronger solar radiation near the equator, are endowed with greater biodiversity. But ecosystems do not exclusively draw their energy directly from the sun. Energy can also be stored chemically, for example in resources such as wood.

Which type of energy promotes biodiversity? Does it happen uniformly along the food chain? These questions have remained unanswered until now.

The first answers have now come from researchers at the Julius-Maximilians-Universität (JMU) Würzburg Biocentre. A team led by ecologists Simon Thorn and Peter Kriegel has studied the species diversity of beetles that live in deadwood in forests. Data from all over Europe was collected for this purpose. Simon Thorn initiated and coordinated the project six years ago; he has recently started research at the Hessian Agency for Nature Conservation, Environment and Geology.

Tuesday, May 2, 2023

Let’s get cracking: Sandia scientists detect gases from fractured rock

Steve Bauer, a retired Sandia National Laboratories geoscientist, is preparing his sensitive mass spectrometer to detect the gases released by crushing a piece of granite. Recently he detected noble gases released by a test explosion underground. Someday this research might improve the prediction of earthquakes or detection of underground explosions.
Photo Credit: Craig Fritz

Geoscientists have detected specific gases being released from fractured rocks in real time after a series of small chemical explosions set underground.

This fundamental research, led by Sandia National Laboratories geoscientist Steve Bauer, could one day improve the prediction of earthquakes or detection of underground explosions.

“In the different shots, we were able to measure different relative amounts of noble gases, which we hope is consistent with the amount of deformation caused by the explosion,” said Bauer, who recently retired. “The chemical explosions had the same amount of TNT equivalent, but produced different amounts of liquids and gases, so they deformed the rock to different extents. My pie-in-the-sky goal is to measure the amount of noble gas at a location after an explosion or earthquake and then be able to understand the amount of strain the rock has experienced.”

Fossil find in California shakes up the natural history of cycad plants

Three-dimensional reconstruction of the whole cone and different views of the same cone scale. Scale bar: cone = 400 microns; cone scales = 200 microns.
Image Credit: Andres Elgorriaga, Brian Atkinson

Cycads, a group of gymnosperms which can resemble miniature palm trees (like the popular sago palm houseplant) were long thought to be “living fossils,” a group that had evolved minimally since the time of the dinosaurs. Now, a well-preserved 80-million-year-old pollen cone discovered in California has rewritten scientific understanding of the plants.

The findings are detailed in a paper by two University of Kansas paleobotanists just published in the journal New Phytologist.

“Cycads aren’t well-known but make up a significant part of plant diversity, accounting for around 25% of all gymnosperms,” said lead author Andres Elgorriaga, postdoctoral researcher with the KU Department of Ecology & Evolutionary Biology and KU Biodiversity Institute and Natural History Museum3. “Cycads are plants that have thick stems and short stature, with thick, palm-like leaves on top. They produce cones like pine cones and are related to other seed-bearing plants that also don’t produce flowers, like Ginkgo and the monkey puzzle tree. But they’re also highly endangered, with the highest level of endangerment among all plant groups. Trafficking of cycads also is a significant issue.”

Why mosses are vital for the health of our soil and Earth

When mosses cover the soil, it's a good sign, not a bad one. They lay foundations for other plant life to thrive.
Photo Credit: University of New South Wales

Often ignored or even removed, moss provides stabilization for plant ecosystems the world over.

Some people see moss growing in their gardens as a problem, but what they may not realize is this ancient ancestor of all plants is bringing lots of benefits to our green spaces, such as protecting against erosion.

Now a massive global study led by UNSW Sydney has found mosses are not just good for the garden, but are just as vital for the health of the entire planet when they grow on topsoil. Not only do they lay the foundations for plants to flourish in ecosystems around the world, they may play an important role mitigating against climate change by capturing vast amounts of carbon.

In a study published today in the journal Nature Geoscience, lead author Dr David Eldridge and more than 50 colleagues from international research institutions described how they collected samples of mosses growing on soil from more than 123 ecosystems across the globe, ranging from lush, tropical rainforest, to barren polar landscapes, through to arid deserts like those found in Australia. The researchers found that mosses cover a staggering 9.4 million km2 in the environments surveyed, which compares in size to Canada or China.

Monday, May 1, 2023

How does climate change affect global bird reproduction?

Avian ecologist Jeff Hoover and his colleagues explored the potential effects of global warming on bird reproductive output across the world. 
Photo Credit: Fred Zwicky

A new study reported in the Proceedings of the National Academy of Sciences assessed changes in the reproductive output of 104 bird species between 1970 and 2019. Illinois Natural History Survey avian ecologist Jeff Hoover, a co-author of the paper, spoke to News Bureau life sciences editor Diana Yates about the findings and how climate change is altering bird ecology and health around the world. 

What is unique about the study?  

This study explored potential effects of global climate change – in particular, warming – on offspring production for over 100 species from more than 200 bird populations across all continents. We looked at data for each of these bird populations over 15 to 49 breeding seasons to consider if changes in local temperatures and precipitation were associated with changes in the average number of offspring produced per female per year.

Beyond effects of a warming climate on individual species’ reproductive output, the study also considered whether climate change may affect offspring production by interacting with other attributes of the birds. Such traits include body mass, migration status, habitat needs, human impacts to local landscapes, the protection/conservation status of sites and whether the birds can produce two broods in a single breeding season. The temporal and spatial scales of this work and the number of species and populations studied were monumental.  

Fish thought to help reefs have poop that’s deadly to corals

A coral-eating butterflyfish on a Moorea reef in July 2019.
Photo Credit: Carsten Grupstra

Feces from fish that are typically thought to promote healthy reefs can damage and, in some cases, kill corals, according to a recent study by Rice University marine biologists.

Until recently, fish that consume algae and detritus — grazers — were thought to keep reefs healthy, and fish that eat coral — corallivores — were thought to weaken reef structures. The researchers found high levels of coral pathogens in grazer feces and high levels of beneficial bacteria in corallivore feces, which they say could act like a “coral probiotic.”

“Corallivorous fish are generally regarded as harmful because they bite the corals,” said Carsten Grupstra, a former graduate student at Rice and lead author of the open-access study in Frontiers in Marine Science. “But it turns out that this doesn’t tell the whole story.”

Thursday, April 27, 2023

Twilight zone at risk from climate change

Photo Credit: PublicDomainPictures

Life in the ocean’s “twilight zone” could decline dramatically due to climate change, new research suggests.

The twilight zone (200m to 1,000m deep) gets very little light but is home to a wide variety of organisms and billions of tons of organic matter.

The new study warns that climate change could cause a 20-40% reduction in twilight zone life by the end of the century.

And in a high-emissions future, life in the twilight zone could be severely depleted within 150 years, with no recovery for thousands of years.

“We still know relatively little about the ocean twilight zone, but using evidence from the past we can understand what may happen in the future,” said Dr Katherine Crichton, from the University of Exeter, and lead author of the study.

The research team, made up of paleontologists and ocean modelers, looked at how abundant life was in the twilight zone in past warm climates, using records from preserved microscopic shells in ocean sediments.

Wednesday, April 26, 2023

Predators decrease prey disease levels but also population size

Microscope image showing a phantom midge larva (genus Chaoborus), top left, preying on a Daphnia dentifera water flea, bottom right. Chaoborus is a fierce predator with a complex “catching basket” on its head for quickly trapping small crustaceans like water fleas.
Photo Credit: Meghan Duffy, University of Michigan.

Nature documentaries will tell you that lions, cheetahs, wolves and other top predators target the weakest or slowest animals and that this culling benefits prey herds, whether it’s antelope in Africa or elk in Wyoming.

This idea has been widely accepted by biologists for many years and was formalized in 2003 as the healthy herds hypothesis. It proposes that predators can help prey populations by picking off the sick and injured and leaving healthy, strong animals to reproduce.

The healthy herds hypothesis has even been used to suggest that manipulating predator numbers to protect prey might be a useful conservation strategy. Even so, hard evidence supporting the hypothesis is scarce, and in recent years many of its assumptions and predictions have been questioned.

In a study published online April 26 in the journal Ecology, a University of Michigan-led research team used a pint-sized predator-prey-parasite system inside 20-gallon water tanks to test the healthy herds hypothesis.

Woodpecker helps managers promote new life in burned forests

A male Black-backed Woodpecker at Silvio O. Conte National Wildlife Refuge, Brunswick, Vermont, USA.
Photo Credit: U.S. Fish and Wildlife Service Northeast Region
(CC BY 2.0)

Scientists have created a tool based on the habitat preferences of the black-backed woodpecker to help forest managers make decisions that promote regrowth and biodiversity following wildfires.

“Wildfire is like a 10,000-piece puzzle, and climate change is rearranging the pieces,” said Andrew Stillman, a postdoctoral researcher at the Cornell Atkinson Center for Sustainability and the Cornell Lab of Ornithology and first author of “Incorporating Pyrodiversity into Wildlife Habitat Assessments for RapidPost-Fire Management: A Woodpecker Case Study,” published April 25 in Ecological Applications.

“Gigantic, severe fires are becoming the new norm in California due to drought, longer burn seasons and dense forests. But birds do really well in landscapes that are ‘pyrodiverse’ – areas where fire results in uneven patches burned at high, medium, and low severity,” Stillman said.

Black-backed woodpeckers love pyrodiversity. They prefer to build their nest cavities in newly burned areas after high severity fires. But they also like to be adjacent to areas that burned at low intensity, where their young can hide from predators among living trees that still provide cover. Because of the species’ unique habitat associations, they are sensitive to the removal of trees after fire, and forest managers use information on the woodpecker to guide their post-fire planning.

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