Showing posts with label Environmental. Show all posts
Showing posts with label Environmental. Show all posts

Wednesday, September 29, 2021

Research finds grave concern for coral reefs


Sabine evaluating a potential deployment site for a mooring in Palau.
Similar to a giant sponge, the ocean absorbs a quarter of the excess CO2 produced every year from human activities (anthropogenic carbon) around the world. Carbon dioxide dissolves in the surface water and through the overturning circulation of ocean currents and mixing processes, is slowly transported into the ocean’s interior—which allows the surface ocean to absorb more CO2. In this cycle, CO2 reacts with the water molecules in the ocean to form carbonic acid in a process known as ocean acidification. Like ocean warming, an increase in ocean acidification can also have a profound impact on marine ecosystems.

University of Hawaiʻi at Mānoa Oceanography Professor Christopher Sabine has devoted his life to understanding the connections between the ocean and anthropogenic carbon. After earning his PhD in chemical oceanography at UH Mānoa in the early 1990s, Sabine spent the next decade conducting high-quality carbon measurements in an effort to better understand where inorganic carbon is stored in the ocean.

Tuesday, September 28, 2021

Dinosaurs' ascent driven by volcanoes powering climate change

 The rise of dinosaurs coincided with environmental changes driven by major volcanic eruptions over 230 million years ago, a new study reveals.

The Late Triassic Carnian Pluvial Episode (CPE) saw an increase in global temperature and humidity - creating a major impact on the development of animal and plant life, coinciding with the establishment of modern conifers.

Researchers analyzed sediment and fossil plant records from a lake in northern China’s Jiyuan Basin, matching pulses of volcanic activity with significant environmental changes, including the CPE’s ‘mega monsoon’ climate, some 234 million to 232 million years ago.

The international research team, including experts at the University of Birmingham, today published their findings in Proceedings of the National Academy of Sciences (PNAS) – revealing four distinct episodes of volcanic activity during this time period, with the most likely source being major volcanic eruptions from the Wrangellia Large Igneous Province, the remnants of which are preserved in western North America.

Monday, September 27, 2021

Journey to Landsat 9


The first Landsat satellite launched in 1972. Since then, NASA has always kept a Landsat in orbit to collect images of the physical material covering our planet’s surface and changes to land usage. Those images allow researchers to monitor phenomena including agricultural productivity, forest extent and health, water quality, coral reef habitat health, and glacier dynamics.

Hyena scavenging provides public health and economic benefits to African cities


Hyenas are frequently vilified and often feared. Hemingway once described the hyena as a stinking, foul devourer of the dead, with jaws that crack the bones the lion leaves.

But a new study concludes that spotted hyena scavenging provides significant public health and economic benefits to the African cities they roam.

In a study conducted in and around the Ethiopian city of Mekelle, home to 310,000 people and 120,000 livestock animals, a University of Michigan conservation ecologist and two colleagues found that spotted hyenas annually remove 207 tons of animal carcass waste.

Mekelle is the capital of northern Ethiopia’s Tigray region. The carcasses of livestock animals that are slaughtered for food there, or that die naturally, are often dumped at the local landfill or on roadsides, where hyenas feed on the waste. The researchers wanted to know whether hyenas—by removing this waste from the environment—might also prevent pathogens from jumping into people and livestock.

They determined that hyena scavenging annually prevents five infections of anthrax and bovine tuberculosis in Mekelle residents and 140 infections in cattle, sheep and goats. This disease-control service potentially saves the city $52,000 annually in treatment costs and livestock losses avoided.

The study, published online Sept. 26 in the Journal of Applied Ecology, is the first to quantify the public health and economic benefits of scavenging by spotted hyenas.

New membrane to make fresh water


Susan Rempe, right, a Sandia National Laboratories bioengineer, and Stephen Percival, a material scientist, examine their biologically inspired electrodialysis membrane for producing fresh water. By mimicking an algae protein, the membrane can remove salt from seawater and wastewater to make fresh water while using less electricity.
(Photo by Randy Montoya)

Scientists at Sandia National Laboratories and their collaborators have developed a new membrane, whose structure was inspired by a protein from algae, for electrodialysis that could be used to provide fresh water for farming and energy production.

The team shared their membrane design in a paper published recently in the scientific journal Soft Matter.

Electrodialysis uses electrical power to remove dissolved salts from water. Currently it is used to capture salt from seawater to produce table salt and remove salt from brackish water to make fresh water, but it could also be used to remove salt from wastewater to provide a new source of fresh water.

The researchers found that the addition of a common amino acid, called phenylalanine, to an electrodialysis membrane enabled it to better capture and remove positive ions, such as sodium.

“Adding phenylalanine to the electrodialysis membrane increased the selectivity for positive ions by a significant amount, to our pleasant surprise,” Susan Rempe, the lead bioengineer on the project, said.

Ensuring an adequate supply of fresh water is a national security problem, she said. Fresh water is essential for everything from drinking and farming to producing energy from nuclear-, coal- and natural-gas-based power plants.

Monday, September 20, 2021

Coral reef biodiversity predicted to shift as climate changes


Experimental set up at HIMB with mesocosms. (Photo credit: Chris Jury)
Coral reefs are among the most biologically diverse, complex and productive ecosystems on the planet. Most of coral reef biodiversity consists of tiny organisms living deep within the three-dimensional reef matrix. Although largely unseen, this diversity is essential to the survival and function of coral reef ecosystems, and many have worried that climate change will lead to dramatic loss of this diversity.

New research led by scientists at the University of Hawaiʻi at Mānoa reveals that the species which dominate experimental coral reef communities shift due to climate change, but the total biodiversity does not decline under future ocean conditions of warming and acidification predicted by the end of the century.

The study was published in the Proceedings of the National Academy of Science.

“Rather than the predicted collapse of biodiversity under ocean warming and acidification, we found significant changes in the relative abundance, but not the occurrence of species, resulting in a shuffling of coral reef community structure,” said Molly Timmers, lead author who conducted this study during her doctoral research at the Hawaiʻi Institute of Marine Biology (HIMB) at UH Mānoa’s School of Ocean and Earth Science and Technology (SOEST).

Important but overlooked organisms

“The tiny organisms living in the reef structure are known as the cryptobiota, which are analogous to the insects in a rainforest,” said Timmers. “They play essential roles in reef processes such as nutrient cycling, cementation and food web dynamics—they are an important diet of many of the fishes and invertebrates that make coral reef ecosystems so dynamic.”

Despite their critical importance to coral reef ecosystems, these cryptobiota are often overlooked in climate change research due to the challenges associated with surveying them using visual census and in identifying this highly diverse and understudied community.

“As a result, our perceptions of coral reef biodiversity across marine gradients and how biodiversity will respond to climatic change has been primarily based on a handful of observable surface-dwelling taxa, such as corals and fish,” said Timmers.

Experimental designs

To assess the responses of the understudied cryptobiota to future ocean conditions, Timmers and colleagues at HIMB devised an experiment wherein tiered settlement plates were placed in experimental flow-through tanks. These mesocosms received unfiltered seawater from a nearby reef slope off the shore of HIMB and were treated with end-of-the-century predicted ocean warming and/or ocean acidification conditions. After two years of exposure, the team examined the organismal groups that had developed on the settlement plates using DNA metabarcoding techniques.

“This two-year experimental mesocosm study is unprecedented for climate change research and is the first one to examine the diversity of the entire coral reef community from microbes and algae to the corals and fishes,” said Chris Jury, the author who developed and maintained the mesocosm system.

Source/Credit: University of Hawaiʻi


Friday, September 17, 2021

Reforestation could help save coral reefs from catastrophe

Increasing reforestation efforts in coastal regions could substantially reduce the amount of sediment run-off reaching coral reefs and improve their resilience, a University of Queensland-led study has found.

The study analyzed more than 5,500 coastal areas from around the world and found that nearly 85 per cent of them leached sediment to coral reefs, the second most serious threat facing the world’s reefs behind climate change.

Dr Andrés Suárez-Castro from UQ’s Centre for Biodiversity and Conservation Science said it was important to address the issue of sediment runoff if efforts to reduce the human impact on reefs were to be successful.

“Increased sedimentation can cause aquatic ecosystems to be more sensitive to heat stress, which decreases the resilience of corals to pressures caused by climate change,” Dr Suárez-Castro said.

“If the link between the land and sea is not recognized and managed separately, any future efforts to conserve marine habitats and species are likely to be ineffective.”

Excess sediment runoff from land clearing and agrichemical pollution along coastlines can increase sediment transport to coastal waters.

Dr Suárez-Castro said one of the impacts of sediment runoff on coral reefs is a massive reduction in light levels that were key for coral and sea grass growth and reproduction.

Image credit: Diego Correa Gomez
One solution proposed by Dr Suárez-Castro and his team is for countries to commit to land and forest restoration in coastal regions, which will help reduce the amount of sediment runoff.

“Reforestation is hugely important as it maintains the stability of soils that are vital in limiting erosion risk – it also helps to trap more sediments and prevent them from reaching aquatic systems,” he said.

“Building coral resilience through reducing sediment and pollution is also key to improving a coral reef’s potential for recovery.

“If land management to reduce sediment runoff does not become a global priority, it will become increasingly challenging, if not impossible, to protect marine ecosystems in the face of climate change.”

The researchers said that while the benefits of land restoration activities were clear, it would be a challenge to get countries and governments to commit to restoration activities.

“It’s encouraging to see many countries with high coral diversity committing large areas to land restoration, however the cost of reforestation, as well as political and social barriers may make it difficult to achieve these ambitious goals,” Dr Suárez-Castro said.

“If an average of 1000 hectares of forest was restored per coastal basin, land-based sediments reaching coral reefs could be cut by an average of 8.5 per cent among 63,000 square kilometers of reefs.”

Dr Suárez-Castro and his team hope that local authorities can use their results to identify areas where reforestation can have the highest benefit on coral reefs.

“Our approach can be adapted with local data to identify optimal actions for preserving ‘win-wins’ for multiple ecosystems spanning the land and sea,” Dr Suárez-Castro said.

“Several global initiatives such as the Paris Climate Agreement are bringing forest restoration to the forefront of global conservation discussions and our hope is that our study can facilitate more informed and educated conversations around the importance of a more integrated land-sea approach.”

The research has been published in Global Change Biology

Source/Credit: University of Queensland


Wednesday, September 15, 2021

Region of 'Super Corals' Discovered

Corals found in an area of the ocean with extremely high levels of
Carbon Dioxide in the Verde Island Passage in the Philippines.
 In 2019, a hydrology professor at The University of Texas at Austin set out on a research project to see if he could identify harmful nutrients flowing through groundwater into a delicate coral reef sanctuary in the Philippines. He achieved this goal, but following the long history of accidental scientific discoveries, he instead stumbled upon something completely unexpected: a region of possible “super corals” that are thriving despite high levels of carbon dioxide.

The findings based on the 2019 field work were published in August in the journal ACS ES&T Water.

For the first time, the UT Austin professor, Bayani Cardenas, and a team of international researchers were able to attribute the source of CO2 and other gases and nutrients in seawater at this location to groundwater, a finding that the researchers believe shows how the undersea reef environment can be vulnerable to the way communities discharge wastewater, agricultural runoff and other byproducts into the sea.

“This is an unseen vulnerability,” said Cardenas, a professor in the Department of Geological Sciences at the UT Jackson School of Geosciences. “We’ve been able to show with this site that groundwater is part of these delicate coral reef environments. There is a connection, and that’s still not as accepted in science and in many parts of the world.”

More than that, Cardenas said the research has led to new questions — and new research proposals — about the super corals they found that could be replicated elsewhere in the coming years as global CO2 levels are expected to rise.

Coral reefs have long been suffering due to climate change, most notably during a global coral bleaching event from 2014 to 2017 that caused heat stress to 75% of the world’s reefs, according to the American Meteorological Society. Yet the coral-filled area Cardenas studied in the Verde Island Passage in the Philippines, a region so vibrant and diverse that he refers to it as the “Amazon of the ocean,” is thriving despite the vast amounts of CO2 being pumped in from groundwater.

Lead author Rogger E. Correa, a researcher at Southern Cross University in Australia, estimated that groundwater is pumping about 989 grams of CO2 per square meter per year into the area they studied, which is known as “Twin Rocks” and borders a chain of volcanoes. That’s the equivalent of parking two cars on the seabed and letting them emit carbon dioxide for a full year on every hectare of reef.

To distinguish groundwater from seawater, the scientists submerged devices that measure the levels of CO2 and radon 222, a naturally occurring radioactive isotope that is found in local groundwater but not in open ocean water. The measurement technique was developed by co-author Isaac Santos, a professor at the University of Gothenburg in Sweden.

This work follows a 2020 study conducted by Cardenas where he discovered CO2 bubbling up from the seafloor off an area of the Philippine coast so dramatically that he dubbed it “Soda Springs.”

The end result from the latest investigation is an entire region of coral reefs that must be studied more closely, said Cardenas, who is a geoscientist and not a coral researcher.

Adina Paytan, a research scientist at the Institute of Marine Sciences at the University of California, Santa Cruz, who was not associated with the study, warned that other human-made stressors, including sedimentation, overfishing and pollution, can still doom coral reefs. But she was heartened that Cardenas’ team showed corals can grow in high-carbon environments, a finding that “provides some hope for the future of corals.”

Study co-authors included researchers from the Leibniz Centre for Tropical Marine Research (ZMT) in Germany; the State Office for Mining, Energy and Geology in Germany; and the following institutions in the Philippines: Ateneo de Manila University, Agricultural Sustainability Initiatives for Nature Inc., and Planet Dive Resort.

Source/Credit: University of Texas at Austin


Troubled waters

Dr Katrina Davis
Associate Professor of Conservation Biology

New research led by the University of Oxford, published in Conservation Letters, has examined the conflict between small-scale fisheries and marine mammals, using the experience of fisheries on the west coast of South America to highlight a worldwide issue.

Globally, conflict between recovering seal and sea lion populations and fishing communities has been escalating. This new research presents a unique overview of this conflict, particularly from the fishers’ perspective, and proposes solutions that will be relevant to many fishing communities around the world. 

In this part of South America, specifically Peru and Chile, marine mammals have been protected since the mid-20th century. Conservation policies have mostly been successful and over the last thirty years marine mammal populations - specifically those of sea lions and seals - have recovered. The study found:

• Nearly 9 out of 10 fishers have a negative impression of sea lions.

• Fishers report that on average sea lions reduce their catch and income by over 50%. 

• Whilst it’s illegal for sea lions and seals to be killed, this is happening regularly with over 70% of fishers admitting that sea lions are being killed to defend catches.

• Fishers’ overwhelming concern is that sea lion populations are now too large. 

To manage this conflict, there’s a need to balance the competing objectives of wildlife conservation with protection for local communities. There’s still concern about sea lion and seal populations because of how recently they’ve recovered, but small-scale fisheries are struggling, and fishers are often earning less than the minimum wage.

The international community needs to incorporate the needs and opinions of fishers in the global dialogue, including considering if protecting human welfare could involve reducing protection for marine mammals. 

‘If the global community is committed to a post-2020 deal for nature and people where improvements to people's wellbeing and nature conservation are both fulfilled - the elusive ‘win-win’ - then governments and scientists must engage with these “messy” local conflicts that repeat across the globe but resist high-level simplification.’ Professor Katrina Davis

'The recovery of marine mammals means that there’s a much higher likelihood that these animals will come into conflict with local fishers.'  Professor Katrina Davis

Sea lions and seals eat the same fish targeted by fisheries, so they’re in competition for resources, and it’s not uncommon for fishers to catch fish that have already been ‘nibbled’ by the marine mammals. They can also be accidentally caught in fishing nets and break them, meaning that the fisheries must pay to replace equipment.  

By understanding fishers’ motivations and perceptions we can develop more effective managerial solutions to the fisheries. Including managing sea lion populations, providing financial compensation for catch losses and gear damage, training programs, and shifting focusing from fishing to eco-tourism. 

Lead author Professor Katrina Davis says, 'A tricky balance must be met between ensuring the future viability of marine mammal populations and ensuring that the livelihoods of small-scale fishers are protected. Fishers perceive that they are suffering large catch and income losses because of sea lions—and it’s these perceptions that we have to manage when we’re developing policy solutions.'

Moving forward, researchers plan to investigate the impact of culls on these interactions, whether this would be viable without harming population levels, and whether it would curb aggression towards marine mammals. 

Source/Credit: University of Oxford


Tuesday, September 14, 2021

Weather Extremes by 2060

In this visualization, based on weather and climate observations from NASA's MERRA dataset, the northern hemisphere's polar jet stream is seen as a meandering, fast-moving belt of westerly winds traversing the lower layers of the atmosphere. Credit: NASA

 New research provides insights into how the position and intensity of the North Atlantic jet stream has changed during the past 1,250 years. The findings suggest that the position of the jet stream could migrate outside of the range of natural variability by as early as the year 2060 under unabated greenhouse gas emissions, with potentially drastic weather-related consequences for societies on both sides of the Atlantic.

Matthew Osman steadies an ice core
drilling barrel into the Greenland Ice Sheet
Credit: Sarah Das/Woods Hole Oceanographic Institution
Led by Matthew Osman, a postdoctoral research associate at the University of Arizona Climate Systems Center, the study is published in Proceedings of the National Academy of Sciences.

Familiar to air travelers flying between North America and Europe, the North Atlantic jet stream is the ribbon of prevailing westerly winds circling the Arctic. Often called the "polar jet," these high-altitude winds impact weather and climate across eastern North America and western Europe, accounting for between 10% and 50% of variance in annual precipitation and temperature in both regions. However, little is known about how the jet stream varied during the past, or how it might change in the future.  

Osman's research team collected glacial ice core samples from nearly 50 sites spanning the Greenland ice sheet to reconstruct changes in windiness across the North Atlantic dating back to the eighth century.  The reconstructions suggest that natural variability has thus far masked the effect of human-caused warming on mid-latitude atmospheric dynamics across annual and longer timescales.

"For most places on Earth, direct climate observations typically do not span more than a few decades," Osman said. "So, we haven't had a great sense of how or why the jet stream changes over longer periods of time. What we do know is that extraordinary variations in the jet stream can have severe societal implications, such as floods and droughts, due to its impacts on weather patterns and so, in terms of thinking about the future, we can now begin to use the past as a sort of a prologue."

The work reveals that although natural variability has largely controlled the position of the North Atlantic jet stream, continued warming could cause significant deviations from the norm. In particular, model projections forecast a northward migration of the North Atlantic jet stream under 21st-century warming scenarios. Such migration could render the jet stream significantly different within a matter of decades.

Although the polar jet stream blows most swiftly near the typical cruising altitudes of planes, the band of winds actually extends all the way to the ground. While of lesser intensity, Osman explained, near the ground the winds are often referred to as storm tracks. Storm tracks impact weather and climate across Greenland, affecting the island's precipitation and temperature changes. By analyzing year-to-year variations in the amount of

snowfall archived in Greenland ice cores, as well as the chemical makeup of the water molecules comprising those annual snow layers, the researchers were able to extract centuries-old clues into how the jet stream changed.

"These layers tell us about how much precipitation fell in a given year and also about the temperatures that air masses were exposed to," Osman said.

Weather events like this summer's heat wave in the Pacific Northwest and the floods in Europe are some recent examples of how the jet stream affects weather patterns based on its intensity or location in the short term, Osman said. But societally significant changes also occur across longer time scales; reconstructing the jet stream's past revealed that in some years, it could be far north, only to venture more than 10 degrees farther south a few years later.

"Such variations have huge implications on the types of weather that people might experience at a given place," Osman said. "For example, when the jet stream is situated farther south, the normally dry Iberian Peninsula tends to experience milder, moister conditions. But, as the jet stream migrates northward, much of that moisture also moves away from Iberia towards already-wet regions of Scandinavia. A poleward-shifted jet stream in the future thus might have similar, but more permanent, consequences."

The team was able to match certain changes in wind speed and geographical shifts to historical weather-related calamities. For example, during a famine that gripped the Iberian Peninsula in 1374, the jet stream was situated unusually far north. Similarly, two famine events in the British Isles and Ireland in 1728 and 1740 coincided with years that winds blew at nearly half their usual intensity, dramatically cooling temperatures and reducing precipitation. The latter of these events, in 1740, is estimated to have cost the lives of nearly half a million people.

Osman and his co-authors expect that any future shifts in the North Atlantic jet stream would also have dramatic implications on day-to-day weather and ecosystems, with trickle-down effects impacting national economies and societies.

"Our results serve as a warning: Although pushing the jet stream beyond its natural range would be problematic, its ultimate trajectory is still largely in our control," he said.

Source/Credit: University of Arizona/Daniel Stolte


Flipping the “genetic paradox of invasions”

A close-up look at a green crab. Image credit: Ted Grosholz

The green crab, Carcinus maenas, is considered a globally distributed invasive species, an organism introduced by humans that eventually becomes overpopulated, with increased potential to negatively alter its new environment. Traditionally, it’s been assumed that successful populations contain high genetic diversity, or a variety of characteristics allowing them to adapt and thrive. On the contrary, the green crab - like many successful invasive populations - has low genetic diversity, while still spreading rapidly in a new part of the world.

A new study led by Carolyn Tepolt, an associate scientist of biology at Woods Hole Oceanographic Institution, is investigating the adaptive mechanisms of the green crab along the west coast of North America, where it has shown extensive dispersal in the last decade despite minimal genetic diversity. The study was published recently in Molecular Ecology and is a collaboration between WHOI, the University of California at Davis, Portland State University, and the Smithsonian Environmental Research Center.

“Invasive species like these are generally unwelcome. Green crabs can compete with native species, rip up eelgrass ‘nurseries’, and eat small shellfish before they have a chance to be harvested. Green crabs can be an ecological menace and an economic burden,” Tepolt said. “In this study, we found that one of the world's most serious marine invasive species has evolved specific genetic variation that likely helps it adapt to new environments really quickly, even when it's lost a lot of genetic diversity overall.”

Genetic diversity refers to small individual-to-individual differences in DNA, and often translates into a range of different inherited traits within a species. A population with high genetic diversity is more likely to include individuals with a wide range of different traits. In order for a population to adjust to changing environments, this variation can be crucial - or so scientists have often thought. Invasive species often challenge this assumption, successfully spreading in new regions despite low genetic diversity caused by descending from a small number of initial colonists.

This study focuses on a northwest Pacific population of green crab that has spread within the last 35 years from a single source. High-profile marine invasive species, such as green crabs, often live across thousands of kilometers of ocean, spanning countless environmental differences, both small and large. Using six U.S. west coast locations spanning over 900 miles from central California to British Columbia, Tepolt and her team examined the species’ genetic structure at thousands of places across its genome. While this population has lost a large amount of overall genetic diversity relative to its European source, a piece of DNA associated with cold tolerance in a prior study appears to be under strong selection from north to south across its invasive West Coast range.

This may represent a type of genetic feature - a balanced polymorphism - that evolved to promote rapid adaptation in variable environments despite high gene flow, and which now contributes to successful invasion and spread in a novel environment. Researchers do occasionally find incredibly successful populations that have passed through severe bottlenecks, dramatically decreasing their genetic diversity relative to their source. This study is amplifying the need to consider that diversity at specific parts of the genome (rather than genome-wide diversity) may play a critical role in resilience in new or changing environments.

“This is exciting for two main reasons. First, the study tests a partial resolution to ‘the genetic paradox of invasions’, demonstrating that variation at key parts of the genome permits rapid adaptation even in a population with low overall genetic diversity. Second, it suggests that high gene flow in a widespread species’ native range may generate evolutionary mechanisms, like this one, which provide that species with the substrate for rapid adaptive change as it spreads across new environments,” Tepolt explained.

Identifying invasive species spread can also be a job for non-scientists. As the climate changes and as humans get better and better at moving stuff around the globe, there’s more potential for species to come along for the ride and expand into new environments. Tepolt says it’s important to keep an eye out for cues, changes in the environment and possible new species in places they haven’t been before. She recommends seizing the opportunity to tell officials and researchers if there is something unusual at the coastline. There may be signs at beaches and boat ramps asking people to keep a lookout for particular species and giving contact information. If there are suddenly green crabs in an area for the first time, for example, on the West Coast in the Salish Sea and in Alaska, they likely should not be there and should be reported.

Source/Credit: Woods Hole Oceanographic Institution


Monday, September 13, 2021

Crop-eating moths will flourish as climate warms

The top map shows the distribution of diamondback moths as of 2016. Overwintering regions are shown in red. The bottom map shows regions where the diamondback moth’s range has expanded in the past 50 years, based on a climate change model in which mean global temperatures will increase 2 degrees Celsius this century. Darker colors indicate a greater chance for overwinter survival.
(Image courtesy of V. Rudolf/Rice University)

Climate change in this century will allow one of the world’s costliest agricultural pests, the diamondback moth, to both thrive year-round and rapidly evolve resistance to pesticides in large parts of the United States, Europe and China where it previously died each winter, according to a study by U.S. and Chinese researchers.

The moth, Plutella xylostella, which is also known as the cabbage moth, already causes more than $4 billion in damage worldwide each year to broccoli, cauliflower, cabbage, kale, mustard, radishes, turnips, watercress, Brussels sprouts and other crops. It is also one the world’s most pesticide-resistant species, with a documented resistance to at least 97 insecticides.

In a first-of-its-kind study published in the open-access journal Nature Communications, researchers from Rice University and the Chinese Academy of Agricultural Sciences combined results from years of laboratory and field experiments, computer simulations of future climate warming scenarios and a meta-analysis of decades of prior moth research.

“It’s well-documented that climate change is shifting the distribution and ranges of species, but the challenge is trying to predict where species will go,” said study co-author Volker Rudolf, an ecologist, evolutionary biologist and professor of biosciences at Rice University.

Rudolf said the team, which was led by co-lead authors Chun-Sen Ma and Wei Zhang, began with laboratory experiments aimed at isolating a specific mechanism that could be used to accurately predict how the range of diamondback moths would evolve in response to climate change. Previous experiments had found the coldest temperature individual moths could survive, but it was also well-known the moths died out each winter in places where temperatures were considerably higher. Rudolf said the lab studies allowed the team to predict where the moths can “overwinter,” or survive year-round, based on the daily accumulated low temperatures below a critical threshold in winter, a metric they dubbed “low temperature degree days.”

“That variable alone predicts over 90% of mortality, which is pretty nuts,” Rudolf said. “You don’t normally get correlations that strong.”

That gave the researchers “a simple variable that was both mechanistically linked to the survival of the species and really easy to calculate from either past climate data or future-climate models,” he said.

Diamondback moth
(This work, “Plutella.xylostella.7383,” by of Olaf Leillinger
is used and provided under
CC BY SA 2.5 courtesy of Wikimedia Commons)
The researchers found climate change over the past 50 years has increased the overwintering range of the diamondback moth by more than 925,000 square miles. They also showed each increase in mean global temperature of 1 degree Celsius will allow the moth’s overwintering range to expand by about 850,000 square miles. Current climate models predict mean global temperatures will increase by 2-6 degrees Celsius during the coming 100-150 years, the study said.

Rudolf said the overwintering data combined with a meta-analysis of decades of previous studies of diamondback moth pesticide resistance allowed the team to show how climate change could dramatically worsen the problem of evolved pesticide resistance in parts of the U.S., China, Japan and the Mediterranean that are currently “marginal” overwintering regions for the moth.

“We care about overwintering because if they survive winters and stay year-round that allows for rapid evolution of pesticide resistance,” Rudolf said.

Diamondback moths and many other crop pests like armyworms, planthoppers, leafrollers and some species of aphids overwinter in warm regions and migrate annually, causing significant damage to crops in regions where they cannot overwinter. Where these species cannot overwinter, they are slower to evolve pesticide resistance, Rudolf said.

“Because they always come from somewhere else to recolonize a particular site, the individuals are most likely coming from different ancestors every year,” he said. “So, you can have within-season selection for pesticide resistance, but selection across-seasons gets interrupted.”

The researchers’ global meta-analysis of pesticide resistance in diamondback moths illustrated the critical difference between these two types of evolutionary processes: Mean pesticide resistance was 158 times higher at overwintering sites compared to non-overwintering sites, the research showed.

The double whammy of an expanded year-round range and more rapid evolution of pesticide resistance could severely impede control efforts and allow diamondback moths to cause greater economic losses for farmers, the study found.

But the study’s authors said the research also presents an opportunity, both as a template for studying similar crop pests and as a guide to designing and coordinating more effective control efforts.

The findings could be used to “develop proactive pest management in a changing world, reduce costs of control efforts and assure food security while minimizing impacts on natural enemies and other aspects of the ecosystem,” they wrote in the study. “In practice, our results emphasize the importance of adjusting pest management strategies to adapt to differences in winter survival across regions and how this will change under future climate scenarios.”

Study co-authors include Yu Peng, Liang Zhu and Gang Ma of the Chinese Academy of Agricultural Sciences in Beijing, Fei Zhao and Kun Xing of both the Chinese Academy of Agricultural Sciences and Shanxi Agricultural University in Shanxi, Xiang-Qian Chang of both the Chinese Academy of Agricultural Sciences and Hubei Academy of Agricultural Sciences in Wuhan, and He-Ping Yang of the National Meteorological Information Centre in Beijing.

The research was supported by the National Natural Science Foundation of China (31471764, 31620103914, 31501630), the National Key R&D Program of China (2018YFD0201400, 2019YFD1002100), the Chinese Academy of Agricultural Sciences’ Fundamental Research Fund (Y2017LM10) and the Chinese Academy of Agricultural Sciences’ Innovation Program (CAAS-ZDRW202012).

Source/Credit: Rice University


Thursday, September 9, 2021

Mystery of icy plumes that may foretell deadly supercell storms


An Above Anvil Cirrus Plume emanates from the top of a storm.
(Image credit: NASA)
The most devastating tornadoes are often preceded by a cloudy plume of ice and water vapor billowing above a severe thunderstorm. New research reveals the mechanism for these plumes could be tied to “hydraulic jumps” – a phenomenon Leonardo Da Vinci observed more than 500 years ago.

When a cloudy plume of ice and water vapor billows up above the top of a severe thunderstorm, there’s a good chance a violent tornado, high winds or hailstones bigger than golf balls will soon pelt the Earth below.

A new Stanford University-led study, published Sept. 10 in Science, reveals the physical mechanism for these plumes, which form above most of the world’s most damaging tornadoes.

Previous research has shown they’re easy to spot in satellite imagery, often 30 minutes or more before severe weather reaches the ground. “The question is, why is this plume associated with the worst conditions, and how does it exist in the first place? That’s the gap that we are starting to fill,” said atmospheric scientist Morgan O’Neill, lead author of the new study.

The research comes just over a week after supercell thunderstorms and tornadoes spun up among the remnants of Hurricane Ida as they barreled into the U.S. Northeast, compounding devastation wrought across the region by record-breaking rainfall and flash floods.

Understanding how and why plumes take shape above powerful thunderstorms could help forecasters recognize similar impending dangers and issue more accurate warnings without relying on Doppler radar systems, which can be knocked out by wind and hail – and have blind spots even on good days. In many parts of the world, Doppler radar coverage is nonexistent.

“If there’s going to be a terrible hurricane, we can see it from space. We can’t see tornadoes because they’re hidden below thunderstorm tops. We need to understand the tops better,” said O’Neill, who is an assistant professor of Earth system science at Stanford’s School of Earth, Energy & Environmental Sciences (Stanford Earth).

Supercell storms and exploding turbulence

The thunderstorms that spawn most tornadoes are known as supercells, a rare breed of storm with a rotating updraft that can hurtle skyward at speeds faster than 150 miles an hour, with enough power to punch through the usual lid on Earth’s troposphere, the lowest layer of our atmosphere.

In weaker thunderstorms, rising currents of moist air tend to flatten and spread out upon reaching this lid, called the tropopause, forming an anvil-shaped cloud. A supercell thunderstorm’s intense updraft presses the tropopause upward into the next layer of the atmosphere, creating what scientists call an overshooting top. “It’s like a fountain pushing up against the next layer of our atmosphere,” O’Neill said.

As winds in the upper atmosphere race over and around the protruding storm top, they sometimes kick up streams of water vapor and ice, which shoot into the stratosphere to form the tell-tale plume, technically called an Above-Anvil Cirrus Plume, or AACP.

The rising air of the overshooting top soon speeds back toward the troposphere, like a ball that accelerates downward after cresting aloft. At the same time, air is flowing over the dome in the stratosphere and then racing down the sheltered side.

Using computer simulations of idealized supercell thunderstorms, O’Neill and colleagues discovered that this excites a downslope windstorm at the tropopause, where wind speeds exceed 240 miles per hour. “Dry air descending from the stratosphere and moist air rising from the troposphere join in this very narrow, crazy-fast jet. The jet becomes unstable and the whole thing mixes and explodes in turbulence,” O’Neill said. “These speeds at the storm top have never been observed or hypothesized before.”

Hydraulic jump

Scientists have long recognized that overshooting storm tops of moist air rising into the upper atmosphere can act like solid obstacles that block or redirect airflow. And it’s been proposed that waves of moist air flowing over these tops can break and loft water into the stratosphere. But no research to date has explained how all the pieces fit together.

The new modeling suggests the explosion of turbulence in the atmosphere that accompanies plumed storms unfolds through a phenomenon called a hydraulic jump. The same mechanism is at play when rushing winds tumble over mountains and generate turbulence on the downslope side, or when water speeding smoothly down a dam’s spillway abruptly bursts into froth upon joining slower-moving water below.

Leonardo DaVinci observed the phenomenon in flowing water as early as the 1500s, and ancient Romans may have sought to limit hydraulic jumps in aqueduct designs. But until now atmospheric scientists have only seen the dynamic induced by solid topography. The new modeling suggests a hydraulic jump can also be triggered by fluid obstacles in the atmosphere made almost entirely of air and which are changing shape every second, miles above the Earth’s surface.

The simulations suggest the onset of the jump coincides with a surprisingly rapid injection of water vapor into the stratosphere, upwards of 7000 kilograms per second. That’s two to four times higher than previous estimates. Once it reaches the overworld, water may stay there for days or weeks, potentially influencing the amount and quality of sunlight that reaches Earth via destruction of ozone in the stratosphere and warming the planet’s surface. “In our simulations that exhibit plumes, water reaches deep into the stratosphere, where it possibly could have more of a long-term climate impact,” said co-author Leigh Orf, an atmospheric scientist at the University of Wisconsin-Madison.

According to O’Neill, high-altitude NASA research aircraft have only recently gained the ability to observe the three-dimensional winds at the tops of thunderstorms, and have not yet observed AACP production at close range. “We have the technology now to go verify our modeling results to see if they’re realistic,” O’Neill said. “That’s really a sweet spot in science.”

This research was supported by the National Science Foundation and the NASA Precipitation Measurement Mission and Ground Validation program.

Source/Credit: Stanford University/Josie Garthwaite


Ancient sea ice core sheds light on modern climate change


A 170 m record of marine sediment cores extracted from Adélie Land in Antarctica by the Integrated Ocean Drilling Program is yielding new insights into the complicated relationship between sea ice and climate change.

In a new study published in Nature Geoscience, researchers at the University of Birmingham, have collaborated in an international project to identify how fluctuations in sea ice levels have interconnected with both algae blooms and weather events linked to El Nino over the past 12,000 years.

They found that Antarctic winds strongly affect the break-out and melting of sea ice, which in turn affects the levels of algae which can grow rapidly in surface waters when sea ice is reduced. Changes in the levels of algae growth in the waters surrounding the Antarctic are important enough to affect the global carbon cycle.

The researchers used techniques such as CT scan (computed tomography) imaging and analysis of microfossils and organic biomarkers, to examine the relationship between sea ice and large algae growth “bloom” events at annual timescales. The findings, produced in partnership with research institutes in New Zealand, Japan, France, Spain and the USA, span the entire Holocene period and have yielded a highly detailed picture of these relationships that can help predict future sea ice, climate and biological interactions.

The researchers found that algal bloom events occurred nearly every year before 4,500 years ago. However, a baseline shift to less frequent algal blooms and the type of algal production after 4.5 thousand years ago, saw bloom events responding to the El Nino Southern Oscillation (ENSO) and other climate cycles as sea-ice levels rapidly increased. Recent work by many of the same team links the expansion of sea ice at this time to glacial retreat and the development of the Ross Ice Shelf, which acts to cool Antarctic surface waters to create a “sea-ice factory”.

Dr James Bendle, of the University of Birmingham’s School of Geography, Earth and Environmental Science, is a co-author on the paper. He said: “While there’s a clear relationship between temperatures rising in the Arctic over recent decades and sea ice melting, the picture is more complex in the Antarctic. That’s because some areas of the Antarctic are warming, but in some areas sea ice has been increasing. Since sea ice reflects incoming sunlight, not only is the warming effect slowed down, but algae are unable to photosynthesize as easily. Climate models currently struggle to predict observed changes in sea ice for the Antarctic, and our findings will help climate researchers build more robust and detailed models.”

He added: “The relationship we have observed with these changing conditions and the ENSO wind fields is particularly significant. We know that El Nino amplifies the effects of climate change in some regions, so any insights linking this with Antarctic Sea ice is fascinating and has implications for how future long-term loss of sea ice may affect food webs in Antarctic waters, as well as carbon cycling processes within this globally important region.”

Dr Katelyn Johnson, of GNS Science, in New Zealand, is the lead author on the paper. She said: “While sea ice that persists from year to year can prevent these large algal blooms from occurring, sea ice that breaks out and melts creates a favorable environment for these algae to grow. These large algae ‘bloom events’ occur around the continent, form the base of the food webs and act as a carbon sink”.

“Unlike the Arctic where rising temperatures have led to reduced sea ice, the relationship in the Antarctic is less clear, as is the subsequent impact on primary productivity. Our new record provides a longer-term view of how sea ice and climate models like ENSO impact the frequency of these bloom events, allowing climate modelers to build more robust models.”

Source/Credit: University of Birmingham


Coral cryopreservation for breeding key to survival


Fragment of endangered Caribbean elkhorn coral grown from cryopreserved sperm.
(Photo credit: Chris Page)
Flash-frozen sperm collected from corals in Florida and Puerto Rico was used to fertilize coral eggs from hundreds of miles away in Curaçao. The juvenile corals raised from this trans-Caribbean coupling demonstrate the reproductive compatibility of coral colonies that would otherwise be too far apart to produce offspring in the wild and they represent the largest wildlife population ever raised from cryopreserved material.

A paper describing this study, by an international team of researchers, including Mary Hagedorn at the University of Hawaiʻi at Mānoa School of Ocean and Earth Science and Technology (SOEST), was published in the Proceedings of the National Academy of Sciences.

The technique could be used as a conservation tool by introducing genetic variation into endangered corals and potentially accelerating their adaptation to climate change.

“Most corals only attempt sexual reproduction once a year and the eggs and sperm are only viable for a short time period,” said Hagedorn, a research biologist at the Smithsonian Conservation Biology Institute and UH Mānoa’s Hawaiʻi Institute of Marine Biology. She is the lead author of this study, and has developed the technique to cryopreserve coral sperm in her laboratory at UH. “Cryopreservation allows us to breed corals with parentage from hundreds of miles apart.”

Assisted gene flow

“Corals are a vital foundation species for reef ecosystems,” said Iliana Baums, professor of biology at Penn State and one of the leaders of the research team. “Reefs provide habitat for astonishing species diversity, protect shorelines and are economically important for fisheries, but they are suffering in many places due to warming ocean waters. Without intervention, we will continue to lose corals to climate change with potentially disastrous consequences.”

Genetic diversity is the fuel for species adaptation. One of the main sources of genetic diversity is sexual reproduction—new combinations of genes are created when a sperm fertilizes an egg. However, sexual reproduction by Caribbean corals in the wild is now vanishingly rare. Worse yet, because corals are sessile creatures (fixed in one place), they have a limited ability to gain new genetic diversity through gene flow, the evolutionary force that increases genetic diversity when distant populations come together, each bringing with them their own unique versions of genes.

“To increase genetic diversity in corals, we can use ‘assisted gene flow’ by bringing corals together that are physically distant in the wild, but this is logistically incredibly difficult,” said Baums.


Most corals reproduce by broadcasting bundles of eggs and sperm into the sea water in a spectacular spawning event timed with the full moon. The researchers collected these bundles from corals in Florida and Puerto Rico, separated the eggs and sperm, and then quickly froze the sperm cells using a liquid nitrogen cryopreservation technique.

“Because these corals only produce eggs and sperm once per year, frozen sperm collected in Florida and Puerto Rico needed to be cryopreserved in advance and stored for over a year until it could be used for a spawning event in Curaçao,” said Baums.

Some of the sperm were kept frozen at the USDA National Animal Germplasm Program’s gene bank for up to 10 years. The frozen sperm was transported to Curaçao where it was thawed and used to fertilize fresh eggs collected locally. The fertilized eggs developed into larvae that were then transported to Mote Marine Laboratory and The Florida Aquarium in Florida, where they were allowed to develop into adults.

Source/Credit: University of Hawaiʻi


A source of hope for coral reefs


A healthy coral reef in the Phoenix Islands Protected Area in 2018.
Photo credit: Michael Fox
Some coral communities are becoming more heat tolerant as ocean temperatures rise, offering hope for corals in a changing climate.

After a series of marine heatwaves hit the Phoenix Islands Protected Area (PIPA) in the central Pacific Ocean, a new study finds the impact of heat stress on the coral communities lessened over time.

While a 2002-2003 heatwave devastated coral communities in PIPA, the reefs recovered and experienced minimal losses during a similar event in 2009-2010. Then, in 2015-2016, a massive heatwave put twice as much heat stress on the corals, yet the die-off was much less severe than expected, according to new research published in Geophysical Research Letters, AGU’s journal for high-impact reports with immediate implications spanning all Earth and space sciences.

The authors of the new study suspect heat-tolerant offspring from the surviving corals are repopulating the reefs, allowing the community to keep pace with warming seas, at least for the time being.

The new study could help coral reef managers identify coral communities most likely to survive in the warming ocean, improving conservation and restoration outcomes.

“It’s easy to lose faith in coral reefs,” said first author Michael Fox, a postdoctoral scientist and coral reef ecologist at the Woods Hole Oceanographic Institution (WHOI). “But in PIPA, which is protected from local stressors, and where reefs have enough time to recover between heatwaves, the coral populations are doing better than expected.”

Underwater heatwaves

Just like on land, heatwaves underwater are becoming more frequent and intense as the world warms, putting stress on ocean ecosystems. High temperatures hit coral reefs especially hard by causing widespread bleaching events, where corals eject the symbiotic algae in their tissues, further weakening the animals. With continued ocean warming, coral reefs face a dim future.

In the new study, researchers monitored coral communities at four islands within PIPA, an area encompassing over 400,000-square-kilometers of coral reef and deep-sea habitat. The Republic of Kiribati established the reserve in 2008, and the United Nations Educational, Scientific and Cultural Organization (UNESCO) designated PIPA as a World Heritage Site in 2010. “The protected area gives us a rare opportunity to study pristine and isolated coral reef ecosystems, a privilege for which we thank the people of Kiribati,” said co-author Anne Cohen, a marine scientist at WHOI.

The team used daily satellite data and temperature loggers to examine how each heatwave impacted the corals. They ruled out 11 environmental factors that might explain the higher-than-expected survival following the 2009-2010 and 2015-2016 heatwaves, such as greater cloud cover or more gradual warming.

After the 2002-2003 heatwave, the surveyed sites lost more than three-quarters of their coral cover. The reef was beginning to recover when the 2009-2010 heatwave hit, sparking fears of widespread bleaching, but two years later, coral cover had increased by more than 5%. Following the “Super El Niño” in 2015-2016, which raised ocean temperatures by 3 degrees Celsius (5.4 degrees Fahrenheit), the loss of coral cover was 40%— about half of the 2002 losses, despite causing twice the level of thermal stress.

A source of hope for coral reefs

Many of the reef-building species survived the heatwaves. “We’re seeing areas that were devoid of corals after 2002-2003 that are now flourishing with most of the original species,” Fox said.

At other reefs worldwide, sometimes only a handful of especially hardy or fast-growing species recover after a bleaching event. Coral larvae can float long distances on ocean currents, but due to PIPA’s isolation, the researchers hypothesize that local heat-tolerant individuals are repopulating the reefs.

Now that the researchers have shown that some coral communities have the potential to keep up with ocean warming, their next step is to figure out how they are doing it.

The findings are “important for giving us hope for the future of coral reefs, and also for helping to maintain support for protecting reefs, including efforts to reduce local threats, like pollution, sedimentation and overfishing that undermine the reefs’ ability to adapt,” said Lizzie McLeod, the Global Reef Systems Lead at the Nature Conservancy, who was not involved in the study.

She recommends reef conservationists prioritize the conservation of heat-tolerant reefs, because they can act as climate refuges that repopulate other sites decimated by heatwaves.

The study’s authors caution that even these remarkable corals have their limits and reversing climate change remains paramount. As heatwaves become more frequent or intense, even heat-tolerant communities could die out.

“We’re in a race against time, so anything that increases the chances that corals are going to make it is really good news,” said Nancy Knowlton, the Sant Chair in Marine Science Emerita at the Smithsonian National Museum of Natural History, who was not part of the study. “The corals are doing their part,” she said. “We have to do ours.”

Source/Credit: Woods Hole Oceanographic Institution


Monday, September 6, 2021

Hidden air pollutants on the rise in cities in India and the UK


Satellite data helped researchers discover rising
 levels of air pollutants
Levels of air pollutants in cities in India are on the rise, according to scientists using observations from instruments on satellites that scan the global skies every day.

Researchers used a long record of data gathered by space-based instruments to estimate trends in a range of air pollutants for 2005 to 2018, timed to coincide with well-established air quality policies in the UK and rapid development in India.

The study was led by the University of Birmingham and UCL and included an international team of contributors from Belgium, India, Jamaica and the UK. The researchers published their findings in the journal Atmospheric Chemistry and Physics, noting that fine particles (PM2.5) and nitrogen dioxide (NO2), both hazardous to health, are increasing in Kanpur and Delhi.

Delhi is a fast-growing megacity and Kanpur was ranked by the WHO in 2018 as the most polluted city in the world. The researchers speculated that increases in PM2.5 and NO2 in India reflect increasing vehicle ownership, industrialization and the limited effect of air pollution policies to date.

This contrasts with trends in the UK cities London and Birmingham, which show modest but ongoing declines in PM2.5 and NOx, reflecting the success of policies targeting sources that emit these pollutants.

They also found increases in the air pollutant formaldehyde in Delhi, Kanpur and London. Formaldehyde is a marker for emissions of volatile organic compounds that include a large contribution from vehicle emissions in India, and, in the UK, an increasing contribution from personal care and cleaning products and a range of other household sources.

Karn Vohra, study lead author and PhD student at the University of Birmingham, commented: “We wanted to demonstrate the utility of satellite observations to monitor city-wide air pollution in the UK where ground-based measurements are in abundance and in India where they are not. Our approach will be able to provide useful information about air quality trends in cities with limited surface monitoring capabilities. This is critical as the WHO estimates that outdoor air pollution causes 4.2 million deaths a year."

Study co-author Professor William Bloss, also from the University of Birmingham, commented “We were surprised to see the increase in formaldehyde above Delhi, Kanpur and London – a clue that emissions of other volatile organic compounds may be changing, potentially driven by economic development and changes in domestic behavior. Our results emphasize the need to monitor our air for the unexpected, and the importance of ongoing enforcement of measures for cleaner air.”

“There is more than a decade of freely available observations from instruments in space to monitor and assess air quality in cities throughout the world. Greater use of these in the UK, India, and beyond is paramount to successful air quality policies”, stated Dr Eloise Marais, Earth observation expert at UCL and conceptual lead of the study.

Source/Credit: University of Birmingham


How climatic changes influence the evolution of oceanic insects

Research team members (from left)
Mr Marc Chang and Assistant Professor Danwei Huang
examining ocean skater specimens
The open oceans are harsh and hostile environments where insects might not be expected to thrive. In fact, only one insect group, ocean skaters, or water striders, has adapted to life on the open seas.

How these insects evolved to conquer the high seas, however, was not known.

Now, a study of the genetics of skaters provides a clue. The answer has to do with when major currents in the eastern Pacific Ocean came into existence with each species of skater evolving to match the unique conditions of those currents.

Scientists from the National University of Singapore (NUS) and Scripps Institution of Oceanography at UC San Diego examined the genetics of three ocean skater species collected with dip nets across the eastern Pacific between Hawaii and Peru. The results of the study revealed that the skaters became specialized on different current systems, as those currents changed into their modern configurations.

The findings could unravel the mystery of how each skater species came to occupy habitats vastly different from those of other insects, and also deepen our understanding of how climate change affects ocean-dwelling organisms.

“It is amazing how the ocean skater’s genetic history is closely tied to that of our oceans,” said study leader Dr Wendy Wang, an entomologist from the Lee Kong Chian Natural History Museum at NUS. “The open ocean is an extremely hostile environment, with direct sunlight throughout the daytime, strong winds and limited food. The abilities of their body covering or cuticle to protect their internal organs from heat and ultraviolet damage, and to survive violent storms and find food in this unique habitat where no other insect could demonstrate their unique ecological roles in the ocean. These characteristics make them fascinating subjects of study for materials science and extreme biological adaptations.”

The research team first reported their findings in the journal Marine Biology on 5 September 2021.

Linking genetic data with climatic changes

Ocean skaters live their entire lives perpetually running about on the surface film of the open seas, enduring lashing storms and feeding on tiny prey trapped on or just below the ocean surface. Currently, there are five known oceanic species of the genus Halobates. While information about where they can be found are well-established, little is known about their genetic variation, and how physical factors like ocean currents, temperature and winds affect their distribution.

The research team conducted a genetic study of three of those skater species collected from offshore Mexico to Peru, and as far out to sea as Hawaii. Most of the specimens were skimmed from the ocean surface with dip nets by Dr Lanna Cheng, a marine biologist at Scripps Oceanography, and study co-author. Dr Cheng is a world expert who has devoted her research to Halobates, and she has been studying the genus for almost five decades.

Dr Wang led the gene sequencing and genetic analysis of nearly 400 specimens across the three species. The researchers uncovered distinct genetic variations among the species that illustrate very different stories of population growth and development during ancient times.

The oldest of them, Halobates splendens, was found to have expanded its population nearly a million years ago. The other two younger species, Halobates micans and Halobates sobrinus, were found to have increased in abundance 100,000 to 120,000 years ago.

These formative dates match past climate events. H. splendens is now found in the rich, productive waters of the cold tongue that originates off the coast of South America as the Peru current. Climatological data showed that this physical feature of cold surface water came into existence a million years ago, just at the same time as the period of growth in the genetic diversity and populations of H. splendens.

The other two species H. sobrinus and H. micans were determined to have diversified in the warm, relatively unproductive waters of Central America. The populations of both species expanded when El Niño climate patterns caused warm ocean water to move into the eastern Pacific Ocean. The El Niño effects were especially strong in the habitats of both H. micans and H. sobrinus about 100,000 years ago, coinciding with the time these species developed their modern genetic patterns and population sizes.

“With no apparent physical boundaries in the open ocean to stop them, Halobates can skate practically from the coast of California across the entire Pacific Ocean to Japan and beyond,” Dr Cheng said. “Two of the species studied in this paper, H. sobrinus and H. splendens, however, have never been found to venture beyond the eastern Pacific Ocean and we didn't know why. This paper gave us the clue from their ancestry."

Scripps Oceanography’s Professor Richard Norris is a paleontologist who, for the study, matched the expansion of ocean skater populations to the time periods when the fossil record suggests the modern currents first formed.

“The genetics show that the three species we studied each had periods of population growth that fit eerily well with geological evidence for when the current systems they live in came into existence,” said Prof Norris. “Perhaps I shouldn’t be surprised, since it is common for marine creatures to specialize on particular ocean conditions, but these skaters live on top of the ocean. Apparently, even the character of the sea spray and water surface film is different enough between currents to matter to these guys.”

Further research

Dr Wang elaborated, “The findings of our study highlight the deep influence of climatic conditions on marine populations. The results also contribute towards understanding the fates of ocean-dwelling organisms as ongoing climate change accelerates in the coming decades.”

To expand their knowledge, the researchers will continue to examine the population dynamics of this enigmatic marine insect by studying their genomes.

“Drawing on the key insights from this study, together with our ongoing work, we aim to connect the evolutionary origins of various Halobates species, and uncover how they came to occupy the surface ocean and coastal habitats in present day,” shared marine biologist and co-author Assistant Professor Huang Danwei from the NUS Department of Biological Sciences, and an alumnus of Scripps Oceanography.

Co-author Mr Marc Cheng added, “Having genetic data is especially useful for organisms such as the ocean skaters which we are studying as we are unable to observe them ethologically in their natural environment to track their population.” He is a doctoral student at NUS who is using DNA sequencing methods to uncover the genetic basis to life on the sea surface.

Source/Credit: National University of Singapore


Friday, September 3, 2021

Birds and mammals evolve faster if their home is rising


Wild Kea, New Zealand  Credit: Pablo Heimplatz
Researchers at the University of Cambridge have combined reconstructions of the Earth’s changing surface elevations over the past three million years with data on climate change over this timeframe, and with bird and mammal species’ locations. Their results reveal how species evolved into new ones as land elevation changed - and disentangle the effects of elevation from the effects of climate.

The study found that the effect of elevation increase is greater than that of historical climate change, and of present-day elevation and temperature, in driving the formation of new species – ‘or speciation’.

In contrast to areas where land elevation is increasing, elevation loss was not found to be an important predictor of where speciation happens. Instead, present-day temperature is a better indicator of speciation in these areas.

The results are published in the journal Nature Ecology and Evolution.

“Often at the tops of mountains there are many more unique species that aren’t found elsewhere. Whereas previously the formation of new species was thought to be driven by climate, we’ve found that elevation change has a greater effect at a global scale,” said Dr Andrew Tanentzap in the University of Cambridge’s Department of Plant Sciences, senior author of the paper.

As land elevation increases, temperature generally decreases and habitat complexity increases. In some cases, for example where mountains form, increasing elevation creates a barrier that prevents species moving and mixing, so populations become reproductively isolated. This is the first step towards the formation of new species.

The effect of increasing elevation on that rate of new species formation over time was more pronounced for mammals than for birds; the researchers think this is because birds can fly across barriers to find mates in other areas. Birds were affected more by present-day temperatures; in birds, variation in temperature creates differences in the timing and extent of mating, risking reproductive isolation from populations of the same species elsewhere.

Until now, most large-scale studies into the importance of topography in generating new species have only considered present-day land elevation, or elevation changes in specific mountain ranges.

“It’s surprising just how much effect historical elevation change had on generating the world’s biodiversity – it has been much more important than traditionally studied variables like temperature. The rate at which species evolved in different places on Earth is tightly linked to topography changes over millions of years,” said Dr Javier Igea in the University of Cambridge’s Department of Plant Sciences, first author of the paper.

He added: “This work highlights important arenas for evolution to play out. From a conservation perspective these are the places we might want to protect, especially given climate change. Although climate change is happening over decades, not millions of years, our study points to areas that can harbor species with greater potential to evolve.”

The researchers say that as the Earth’s surface continues to rise and fall, topography will remain an important driver of evolutionary change.

This research was funded by Wellcome, the Gatsby Charitable Foundation and the Isaac Newton Trust.

Source/Credit: University of Cambridge


Warming Atlantic forces whales into new habitats, danger


Source: Pexels
Warming oceans have driven the critically endangered North Atlantic right whale population from its traditional and protected habitat, exposing the animals to more lethal ship strikes, disastrous commercial fishing entanglements and greatly reduced calving rates.

Without improving its management, the right whale populations will decline and potentially become extinct in the coming decades, according to a Cornell- and University of South Carolina-led report in the Sept. 1 journal Oceanography.

“Most of the warming in the Gulf of Maine is not coming from the atmosphere or ocean surface, as one may think,” said senior author Charles Greene, professor emeritus in the Department of Earth and Atmospheric Sciences in the College of Agriculture and Life Sciences. “It is coming from invading slope water many hundreds of feet below the ocean surface, forcing the right whales to abandon their traditional habitat.”

Since 2010, the calving rate has declined and the right whale population has dropped by an estimated 26%, according to the paper. At the beginning of the decade, the North Atlantic right whale population had numbered over 500. Now, the North Atlantic Right Whale Consortium estimates the population at just 356 whales.

The species is considered critically endangered by the International Union for Conservation of Nature Red List of Threatened Species.

Individual whales are not interchangeable; each right whale has its own name and personality, and scientists know them quite well. The whales have been given monikers including Tux, Popcorn, Arrow and Sundog. When scientists spot the right whales, they log the sighting into an international catalog for a perpetually updated census.

“Right whales are one of the best studied, best understood populations in the ocean,” said Greene., a faculty fellow at the Cornell Atkinson Center for Sustainability. “We basically know every individual. It’s very rare that you can study a population where you know everybody.”

And when the right whales have run-ins with humans, such as large ships or commercial fishing lines, scientists can easily identify their carcasses.

The warm slope water entering the Gulf of Maine at depth derives its heat from the Gulf Stream. As the tail end of the Atlantic Meridional Overturning Circulation, the Gulf Stream has changed its trajectory dramatically during the past ten years.

“Due to a warming climate, the Atlantic Meridional Overturning Circulation is slowing down, causing the Gulf Stream to move North, injecting warmer and saltier slope water into the Gulf of Maine,” Greene said.

The warming Gulf of Maine has reduced the abundance of copepods, the tiny crustaceans that serve as the right whales’ favorite snack. This has reduced right whale calving rates and forced the whales to abandon their mid-summer feeding grounds in the Gulf of Maine. Instead, the whales have headed north to the cooler waters of the Gulf of St. Lawrence.

Since 2015, scientists have witnessed an increased number of right whales feeding in the Gulf of St. Lawrence, where there were no protections in place to prevent ship strikes and fishing gear entanglement. This has led to an Unusual Mortality Event declared by NOAA in 2017, when 17 right whale deaths were confirmed, mostly in the Gulf of St. Lawrence. Ten right whales were found dead in 2019, while for 2020 and 2021, four deaths have occurred thus far.

“Right whales continue to die each year,” said lead author Erin Meyer-Gutbrod, Ph.D. ’16, assistant professor at the University of South Carolina. “Protective policies must be strengthened immediately before this species declines past the point of no-return.”

Ocean scientists are hoping for new policies on rope-free fishing gear, vessel speed limit enforcement and money for monitoring and ecosystem forecasting.

“Right whale populations can shift quickly and unexpectedly in our changing climate,” Meyer-Gutbrod said. “There is no time to waste.”

In addition to Greene and Meyer-Gutbrod, co-authors on the research, “Ocean Regime Shift is Driving Collapse of the North Atlantic Right Whale Population,” are Kimberley T.A. Davies, assistant professor, University of New Brunswick, Canada; and David G. Johns, head of the Continuous Plankton Recorder Survey, Marine Biological Association of the United Kingdom, Plymouth, United Kingdom.

Funding for this research was provided by the Lenfest Ocean Program.

Source/Credit: Cornell University / Blaine Friedlander


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