Tiger shark migrations altered by climate change, new study finds

New migration patterns leave sharks more vulnerable to fishing

Peer-Reviewed Publication

UNIVERSITY OF MIAMI ROSENSTIEL SCHOOL OF MARINE & ATMOSPHERIC SCIENCE

 

VIDEO: IN A NEW STUDY, NEIL HAMMERSCHLAG, PH.D., AND COLLEAGUES USED MULTIPLE APPROACHES TO EVALUATE THE EFFECTS OF OCEAN WARMING ON TIGER SHARK MOVEMENTS IN THE WESTERN NORTH ATLANTIC. OVER THE PAST ~40 YEARS, SHARK DISTRIBUTIONS HAVE EXPANDED POLEWARD, PARALLELING RISING TEMPERATURES. MOREOVER, SATELLITE TRACKING OF SHARKS OVER THE PAST DECADE HAS REVEALED THEIR ANNUAL MIGRATIONS HAVE EXTENDED FARTHER POLEWARD AND ARRIVAL TIMES TO NORTHERN AREAS HAVE ALSO OCCURRED EARLIER IN THE YEAR DURING EXTREMELY WARM PERIODS, WHICH HAS SUBSEQUENTLY DECREASED THEIR PROTECTIONS FROM FISHING. POTENTIAL CONSEQUENCES OF THESE CLIMATE-DRIVEN ALTERATIONS INCLUDE INCREASING SHARK VULNERABILITY TO FISHING, DISRUPTION OF PREDATOR-PREY INTERACTIONS AND CHANGES IN ENCOUNTER RATES WITH HUMANS. HAMMERSCHLAG, N., MCDONNELL, L. H., RIDER, M. J., STREET, G. M., HAZEN, E. L., NATANSON, L. J., MCCANDLESS, C. T., BOUDREAU, M. R., GALLAGHER, A. J., PINSKY, M. L., & KIRTMAN, B. (2022). OCEAN WARMING ALTERS THE DISTRIBUTIONAL RANGE, MIGRATORY TIMING, AND SPATIAL PROTECTIONS OF AN APEX PREDATOR, THE TIGER SHARK (GALEOCERDO CUVIER). GLOBAL CHANGE BIOLOGY, 00, 1–16. view more 

CREDIT: UNIVERSITY OF MIAMI ROSENSTIEL SCHOOL OF MARINE AND ATMOSPHERIC SCIENCE

A new study led by scientists at the University of Miami (UM) Rosenstiel School of Marine and Atmospheric Science revealed that the locations and timing of tiger shark movement in the western North Atlantic Ocean have changed from rising ocean temperatures. These climate-driven changes have subsequently shifted tiger shark movements outside of protected areas, leaving the sharks more vulnerable to commercial fishing.

The movements of tiger sharks, (Galeocerdo cuvier) the largest cold-blooded apex predator in tropical and warm-temperate seas, are constrained by the need to stay in warm waters. While waters off the U.S. northeast coastline have historically been too cold for tiger sharks, temperatures have warmed significantly in recent years making them suitable for the tiger shark.

“Tiger shark annual migrations have expanded poleward, paralleling rising water temperatures,” said Neil Hammerschlag, director of the UM Shark Research and Conservation Program and lead author of the study. “These results have consequences for tiger shark conservation, since shifts in their movements outside of marine protected areas may leave them more vulnerable to commercial fishing.”

Hammerschlag and the research team discovered these climate-driven changes by analyzing nine years of tracking data from satellite tagged tiger sharks, combined with nearly forty years of conventional tag and recapture information supplied by the National Oceanic and Atmospheric Administration (NOAA) Cooperative Shark Tagging Program and satellite derived sea-surface temperature data.

The study found that during the last decade, when ocean temperatures were the warmest on record, for every one-degree Celsius increase in water temperatures above average, tiger shark migrations extended farther poleward by roughly 250 miles (over 400 kilometers) and sharks also migrated about 14 days earlier to waters off the U.S. northeastern coast.

The results may have greater ecosystem implications. “Given their role as apex predators, these changes to tiger shark movements may alter predator-prey interactions, leading to ecological imbalances, and more frequent encounters with humans.” said Hammerschlag.

The study, titled “Ocean warming alters the distributional range, migratory timing, and spatial protections of an apex predator, the tiger shark (Galeocerdo cuvier)” was published January 13, 2022 in the journal Global Change Biology.

The study’s authors include: Neil Hammerschlag, Laura McDonnell, Mitchell Rider, Ben Kirtman from the UM Rosenstiel School; Garrett Street and Melanie Boudreau from Mississippi State University; Elliott Hazen, Lisa Natanson, Camilla McCandless from NOAA Fisheries; Austin J. Gallagher from Beneath the Waves; and Malin Pinsky from Rutgers University.

The Batchelor Foundation, Disney Conservation Fund, Wells Fargo, Guy Harvey Ocean Foundation, the Herbert W. Hoover Foundation, the International Seakeepers Society, Oceana, Hoff Productions for National Geographic, and the West Coast Inland Navigation District provided support for the study.

Link to video: https://youtu.be/vyLbf7KSXAk

About the University of Miami

The University of Miami is a private research university and academic health system with a distinct geographic capacity to connect institutions, individuals, and ideas across the hemisphere and around the world. The University’s vibrant and diverse academic community comprises 12 schools and colleges serving more than 17,000 undergraduate and graduate students in more than 180 majors and programs. Located within one of the most dynamic and multicultural cities in the world, the University is building new bridges across geographic, cultural, and intellectual borders, bringing a passion for scholarly excellence, a spirit of innovation, a respect for including and elevating diverse voices, and a commitment to tackling the challenges facing our world. Founded in the 1940’s, the Rosenstiel School of Marine and Atmospheric Science has grown into one of the world’s premier marine and atmospheric research institutions. Offering dynamic interdisciplinary academics, the Rosenstiel School is dedicated to helping communities to better understand the planet, participating in the establishment of environmental policies, and aiding in the improvement of society and quality of life. www.rsmas.miami.edu.

  

CAPTION

In a new study, Neil Hammerschlag, Ph.D., and colleagues used multiple approaches to evaluate the effects of ocean warming on tiger shark movements in the Western North Atlantic. Over the past ~40 years, shark distributions have expanded poleward, paralleling rising temperatures. Moreover, satellite tracking of sharks over the past decade has revealed their annual migrations have extended farther poleward and arrival times to northern areas have also occurred earlier in the year during extremely warm periods, which has subsequently decreased their protections from fishing. Potential consequences of these climate-driven alterations include increasing shark vulnerability to fishing, disruption of predator-prey interactions and changes in encounter rates with humans. Hammerschlag, N., McDonnell, L. H., Rider, M. J., Street, G. M., Hazen, E. L., Natanson, L. J., McCandless, C. T., Boudreau, M. R., Gallagher, A. J., Pinsky, M. L., & Kirtman, B. (2022). Ocean warming alters the distributional range, migratory timing, and spatial protections of an apex predator, the tiger shark (Galeocerdo cuvier). Global Change Biology, 00, 1–16.

CREDIT

Bianca Rangel

 

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JOURNAL

Global Change Biology

DOI

10.1111/gcb.16045 

METHOD OF RESEARCH

Data/statistical analysis

SUBJECT OF RESEARCH

Animals

ARTICLE TITLE

Ocean warming alters the distributional range, migratory timing, and spatial protections of an apex predator, the tiger shark (Galeocerdo cuvier).

ARTICLE PUBLICATION DATE

13-Jan-2022

COI STATEMENT

none

The “gold” of the Midas cichlids

Peer-Reviewed Publication

UNIVERSITY OF KONSTANZ

All he touched turned to gold – says the legend of King Midas from Greek mythology. All Midas cichlids from Central America start out life as black-and-white striped fish and then, almost magically, some of these fishes gradually lose their black colouration and turn bright golden. Behind the "golden touch", which most probably plays a role here, is not the Greek god Dionysus, but a heretoforth unknown gene of the fishes. A team of scientists led by Konstanz biologist Professor Axel Meyer has now published the discovery and characterization of the gene along with a description of different variants that might be the reason for the colour polymorphism in these fishes in the journal Nature Communications.

One species, different versions
Sometimes individuals of the same species differ greatly in their shape or colouration. Scientifically, this phenomenon is referred to as "polymorphism". The 13 fish species that belong to the Central American Midas cichlids (Amphilophus cf. citrinellus) and live in crater lakes in Nicaragua are a vivid example of this: While these fishes always have a dark colouration at first, the "genetically golden" ones turn orange – usually when they become sexually mature – so that there are two colour variants among the adults.

The colour change from dark to "golden", which occurs in about ten percent of the animals, is strictly speaking a decolourization: Over the course of a few weeks, more and more cells containing the dark pigment melanin in the skin of the fishes die and thus cause the bright orange/yellow colour of the adult "golden" animals. This pigment is the same that determines the colour of hair and eyes in humans. So it is the loss of dark, melanin-containing cells that brings out the vibrant colours of the fishes.

In search of the genetic cause
As the colouration of the Midas cichlids has fascinated scientists since its discovery over 100 years ago, it has already been known that the gold colouration is passed on from one generation to the next. The inheritance of the trait follows classical Mendelian rules and the gold colouration is the dominant trait. "Similar to us humans, the chromosome set of the fishes is present in duplicate in every cell. Since the golden colouration is dominant over the dark colour type, a single genetic copy of the 'gold variant' per cell is sufficient for the fishes to develop the golden colouration in the course of their lives," explains Axel Meyer, professor at the Department of Biology at the University of Konstanz.

In past studies, the Meyer-lab was able to narrow down the location of the genetic cause for the colour polymorphism of the Midas cichlids to chromosome 11. However, the genetic mechanism itself responsible for the colour-change of the fishes had remained unknown until now. To get to the bottom of the mystery, the researchers analyzed genetic material from dark and golden Midas cichlids from different crater lakes using "association mapping". The observable trait of colouration is mapped onto a genetic map of the fishes’ genome through genetic crossing over generations, whereby the variation between cohorts of siblings and their grandparents allows to localize the genetic cause of the trait on the genetic map. "The first thing we noticed in this analysis were inconsistencies in the results. Something did not quite fit, literally a piece of the puzzle was missing", says Axel Meyer.

The "goldentouch" gene
The Konstanz scientists suspected that the already existing reference genome of the Midas cichlid used for the analysis might be incomplete in the sense that it does not contain the gene responsible for the colouration at all. Consequently, they decided to produce an improved reference genome using the new "long-read" sequencing method. This part of the study was mainly carried out by Dr Frederico Henning, now professor at the Federal University of Rio de Janeiro (Brazil), and Dr Claudius Kratochwil, now working as a group leader at the University of Helsinki (Finland). Both are former postdocs of Axel Meyer's research group. To do this, the complete genome of a lab-raised Midas cichlid that was heterozygous for colouration was sequenced. Heterozygous means that the individual fish has the genetic information for the golden colouration on one copy of its chromosome 11, and that for the dark colour variant on its other chromosome 11. Then the researchers repeated their original analysis.

"We first discovered a previously undescribed gene on chromosome 11 in our new reference genome, which was present in two different variants in our fish: Variant d for 'dark' and variant G for 'golden'," Axel Meyer reports. Repeating the mapping studies then revealed that this gene is very likely to be associated with the colouration of the Midas cichlids: Fishes with a double copy of the d variant showed a dark colouration in adulthood, whereas those with one or two copies of the dominant G variant showed an orange/yellow colouration. In reference to the legend of King Midas, the researchers named the newly discovered gene "goldentouch".

Further investigations
The results thus provided the first strong indication that the goldentouch gene is likely to play a significant role in the development of different colour variants in Midas cichlids. To learn more about the newly described gene, the researchers continued with a series of molecular follow-up experiments. Initially, they found that the gold variant of the gene is significantly longer than the dark variant. The reason for this is a piece of selfish DNA that has migrated into the gene – a "jumping gene" or "transposon". This extra piece of genetic code causes the gold variant of the gene to fold differently at the molecular level than the dark variant. This in turn has consequences for the gene expression – the synthesis of proteins as the end product of the information contained in the gene.

The researchers also found that in all colour variants of the Midas cichlid, the gene is switched on mainly in the scales, but almost not at all in other locations, such as the internal organs. This underpins a specific function of the gene products in the outer skin layers of the fishes. "We also found that the goldentouch gene is expressed to a lesser extent in the scales of the golden Midas cichlids than in the dark ones. So there are differences in the number of gene products between the colour variants, which might explain the different colour types," Axel Meyer explains.

Thus, even if the final proof that the variants of the goldentouch gene described in the current study are the direct cause for the development of the colour variants in the Midas cichlid is still pending, there are already several indications that this is the case. "With our study, we have come a big step closer to deciphering the mystery of the Midas cichlids. In future studies, we will have to confirm the causal link to the goldentouch gene and figure out how the gene controls the colour change of the fishes at the molecular level in detail", Axel Meyer adds.
 

Key facts: Original publication: Claudius F. Kratochwil, Andreas F. Kautt, Alexander Nater, Andreas Härer, Yipeng Liang, Frederico Henning, Axel Meyer (2022): An intronic transposon insertion associates with a trans-species color polymorphism in Midas cichlid fishes. Nature Communications; DOI: https://doi.org/10.1038/s41467-021-27685-8 Biologists from Konstanz describe a new gene in the Central American Midas cichlid fish and name it "goldentouch" referring to the legend of King Midas. The researchers identify a newly discovered variant of the gene that presumably causes the golden colouration found in about ten percent of the otherwise dark-coloured adult animals. The gold variant was caused by the insertion of a "jumping gene" (transposon). The consequence of this transposon insertion is that the gene folds differently at the molecular level (structural variant), which in turn has an impact on the synthesis of proteins in the scales of the fishes. Scientific contact for interviews: Professor Axel Meyer, University of Konstanz; phone: + 49 7531 88-4163, -88-3069; email: axel.meyer@uni-konstanz.de Funding sources: European Research Council (ERC), German Research Foundation (DFG), European Molecular Biology Organization (EMBO), Swiss National Science Foundation, Instituto Serrapilheira, CAPES, Baden-Württemberg foundation (BWS) as well as start-up funding from the University of Helsinki

Note to editors:
You can download a photo here:
https://cms.uni-konstanz.de/fileadmin/pi/fileserver/2022/das_gold.jpg
Caption: A pair of Midas cichlids (here: Amphilophus xiloaensis) from the Nicaraguan crater lake Xiloá, protecting their offspring.
Copyright: Ad Konings, Cichlid Press

Contact:
University of Konstanz
Communications and Marketing
Phone: + 49 7531 88-3603
Email: kum@uni-konstanz.de

- uni.kn/en

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JOURNAL

Nature Communications

DOI

10.1038/s41467-021-27685-8 

Swapping just one food item per day can make diets substantially more planet-friendly

Americans who eat beef could slash their diet’s carbon footprint as much as 48 percent by swapping just one serving per day for a more planet-friendly alternative, according to a new study

Peer-Reviewed Publication

TULANE UNIVERSITY

 

IMAGE: LEAD AUTHOR DIEGO ROSE, A PROFESSOR OF NUTRITION AND FOOD SECURITY AT TULANE UNIVERSITY SCHOOL OF PUBLIC HEALTH AND TROPICAL MEDICINE. view more 

CREDIT: TULANE UNIVERSITY

If your New Year’s resolution is to eat better for the planet, a new Tulane University study finds it may be easier than you think. 

Americans who eat beef could slash their diet’s carbon footprint as much as 48 percent by swapping just one serving per day for a more planet-friendly alternative, according to a new study published in The American Journal of Clinical Nutrition.

Using real-world data from a survey of what more than 16,000 Americans eat in an average day, researchers from Tulane University School of Public Health and Tropical Medicine and the University of Michigan calculated how much of a difference people could make if they swapped one high-impact food item for similar, more sustainable options. They examined how the change would impact two metrics — their daily diets’ greenhouse gas emissions and water scarcity footprint, a measure of the irrigated water used to produce the foods they eat that takes into account regional variations in water scarcity.

The highest impact item in Americans’ diet is beef and around 20 percent of survey respondents ate at least one serving of it in a day. If they collectively swapped one serving of beef — for example, choosing ground turkey instead of ground beef — their diets’ greenhouse gas emissions fell by an average of 48 percent and water-use impact declined by 30 percent.

“People can make a significant difference in their carbon footprint with very simple changes — and the easiest one would be to substitute poultry for beef,” said lead author Diego Rose, a professor of nutrition and food security at Tulane University’s School of Public Health and Tropical Medicine.

The study also examined how the change would affect the overall environmental impact of all food consumption in the U.S. in a day — including the 80 percent of diets without any changes. If only the 20 percent of Americans who ate beef in a day switched to something else for one meal, that would reduce the overall carbon footprint of all U.S. diets by 9.6 percent and reduce water-use impacts by 5.9 percent.

Agricultural production accounts for about a quarter of global greenhouse gas emissions and about 70 percent of global freshwater withdrawals. For the study, researchers built an extensive database of the greenhouse gas emissions and water use related to the production of foods and linked it to a large federal survey that asked people what they ate over a 24-hour period.

Although swapping beef had the greatest impact, they also measured the impact of changing other items. Replacing a serving of shrimp with cod reduced greenhouse gas emissions by 34 percent; replacing dairy milk with soymilk resulted in an 8 percent reduction. 

The greatest reduction in the water scarcity footprint came from replacing asparagus with peas, resulting in a 48 percent decrease. Substituting peanuts in place of almonds decreased the water scarcity footprint by 30 percent.

Although individual substitutions were the focus of the study, Rose said that addressing climate change must involve more than singular actions.

“The changes needed to address our climate problems are major. They are needed across all sectors and along all levels of human organization from international agencies to federal and state governments to communities and households,” Rose said. “Many individuals feel strongly about this and wish to change our climate problem through direct actions that they can control. This, in turn, can change social norms about both the seriousness of the problem and the potential solutions that can address it. Our study provides evidence that even simple steps can assist in these efforts.”
 

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JOURNAL

American Journal of Clinical Nutrition

DOI

10.1093/ajcn/nqab338 

METHOD OF RESEARCH

Meta-analysis

SUBJECT OF RESEARCH

People

ARTICLE TITLE

Single-item substitutions can substantially reduce the carbon and water scarcity footprints of US diets

ARTICLE PUB

Martian meteorite’s organic materials origin not biological, formed by geochemical interactions between water and rock

The search for life on Mars can teach us about the reactions that led to the building blocks of life on early Earth

Peer-Reviewed Publication

CARNEGIE INSTITUTION FOR SCIENCE

 

IMAGE: THE ALLAN HILLS 84001 METEORITE COURTESY OF NASA/JSC/STANFORD UNIVERSITY. view more 

CREDIT: COURTESY OF NASA/JSC/STANFORD UNIVERSITY.

Washington, DC—Organic molecules found in a meteorite that hurtled to Earth from Mars were synthesized during interactions between water and rocks that occurred on the Red Planet about 4 billion years ago, according to new analysis led by Carnegie’s Andrew Steele and published by Science.  

The meteorite, called Allan Hills (ALH) 84001, was discovered in the Antarctic in 1984 and is considered one of the oldest known projectiles to reach Earth from Mars.  

“Analyzing the origin of the meteorite’s minerals can serve as a window to reveal both the geochemical processes occurring early in Earth’s history and Mars’ potential for habitability,” explained Steele, who has done extensive research on organic material in Martian meteorites and is a member of both the Perseverance and Curiosity rovers’ science teams.

Organic molecules contain carbon and hydrogen, and sometimes include oxygen, nitrogen, sulfur, and other elements. Organic compounds are commonly associated with life, although they can be created by non-biological processes as well, which are referred to as abiotic organic chemistry. 

For years, scientists have debated the origin story for the organic carbon found in the Allan Hills 84001 meteorite, with possibilities including various abiotic process related to volcanic activity, impact events on Mars, or hydrological exposure, as well as potentially the remnants of ancient life forms on Mars or contamination from its crash landing on Earth.  

The Steele-led team, which also included Carnegie’s Larry Nittler, Jianhua Wang, Pamela Conrad, Suzy Vitale, and Vincent Riggi as well as researchers from GFZ German Research Centre for Geosciences, Free University of Berlin, NASA Johnson Space Center, NASA Ames Research Center, and Rensselaer Polytechnic Institute, used a variety of sophisticated sample preparation and analysis techniques—including co-located nanoscale imaging, isotopic analysis, and spectroscopy—to reveal the origin of organic molecules in the Allan Hills 84001 meteorite.

They found evidence of water-rock interactions similar to those that happen on Earth. The samples indicate that the Martian rocks experienced two important geochemical processes. One, called serpentinization, occurs when iron- or magnesium-rich igneous rocks chemically interact with circulating water, changing their mineralogy and producing hydrogen in the process.  The other, called carbonization, involves interaction between rocks and slightly acidic water containing dissolved carbon dioxide and results in the formation of carbonate minerals.

It is unclear whether these processes were induced by surrounding aqueous conditions simultaneously or sequentially, but the evidence indicates that the interactions between water and rocks did not occur over a prolonged period. What is evident, however, is that the reactions produced organic material from the reduction of carbon dioxide.

These mineralogical features are rare in Martian meteorites, and while carbonation and serpentinization have been shown in orbital surveys of Mars and carbonation has been found in other, less-ancient, Martian meteorites, this is the first instance of these processes occurring in samples from ancient Mars. Organic molecules have been detected by Steele in other Martian meteorites and from his work with the Sample Analysis at Mars (SAM) team on the Curiosity rover, indicating that abiotic synthesis of organic molecules has been a part of Martian geochemistry for much of the planet’s history.

“These kinds of non-biological, geological reactions are responsible for a pool of organic carbon compounds from which life could have evolved and represent a background signal that must be taken into consideration when searching for evidence of past life on Mars,” Steele concluded. “Furthermore, if these reactions happened on ancient Mars, they must have happened on ancient Earth, and could possibly explain the results from Saturn’s moon Enceladus as well. All that is required for this type of organic synthesis is for a brine that contains dissolved carbon dioxide to percolate through igneous rocks. The search for life on Mars is not just an attempt to answer the question ‘are we alone?’ It also relates to early Earth environments and addresses the question of ‘where did we come from?’”

_____

The US Antarctic meteorite samples were recovered by the Antarctic Search for Meteorites (ANSMET) program, which has been funded by NSF and NASA and characterized and curated by the Department of Mineral Sciences of the Smithsonian Institution and the Astromaterials Acquisition and Curation Office at NASA Johnson Space Center, respectively.

This work was funded by NASA, Carnegie’s Earth and Planets Laboratory, and the Helmholtz Recruiting Initiative program.

The Carnegie Institution for Science (carnegiescience.edu) is a private, nonprofit organization headquartered in Washington, D.C., with three research divisions on both coasts. Since its founding in 1902, the Carnegie Institution has been a pioneering force in basic scientific research. Carnegie scientists are leaders in the life and environmental sciences, Earth and planetary science, and astronomy and astrophysics.

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DOI

10.1126/science.abg7905 

METHOD OF RESEARCH

Experimental study

SUBJECT OF RESEARCH

Not applicable

ARTICLE TITLE

Organic synthesis associated with serpentinization and carbonation on early Mars

ARTICLE PUBLICATION DATE

14-Jan-202

The role of risk aversion in the coal contracting behavior of US power plants

Peer-Reviewed Publication

UNIVERSITY OF CHICAGO PRESS JOURNALS

A new paper published in the Journal of the Association of Environmental and Resource Economists provides empirical evidence that risk aversion plays an important role in the coal contracting behavior of US power plants.

In “Regulatory Induced Risk Aversion in Coal Contracting at US Power Plants: Implications for Environmental Policy,” author Akshaya Jha notes that from 1983 to 1997, US power plants purchased the majority of their input coal from long-term contracts, consistently paying contract prices in excess of prevailing spot coal prices. Jha proposes a regulatory mechanism for why power plants specifically might exhibit risk aversion when purchasing inputs, arguing that regulators in practice are less likely to incorporate high input cost realizations into the output price they set for utilities. Utilities respond to this regulatory practice by taking costly actions to reduce the variance of their input costs.

Jha specifies an illustrative model in which an expected profit-maximizing firm receives a regulated revenue stream. This regulated revenue stream only reimburses the firm for total costs below a particular "prudence" threshold. Jha demonstrates that the price-regulated firm in this framework does not minimize expected total costs, instead expressing preferences for both a lower expected total cost and a lower variance in total.

Jha estimates the degree of risk aversion exhibited by US power plants using transaction-level data on the coal purchases made by virtually every power plant in the United States from 1983–97. The spot price uncertainty faced by each plant in each month is estimated using a panel-data version of a third-order autoregressive model for the growth rate of spot prices; both the mean and the variance of this growth rate are allowed to vary by the region where the plant is located and month of year.

Jha finds that power plants facing more spot coal price uncertainty sign longer duration coal contracts, purchase contract coal from a larger number of origin counties, and pay higher contract coal prices on average. To put his estimates in perspective, Jha notes, “if every power plant purchased all of their coal from the spot market, the annual aggregate cost savings would be $2.9 billion on average.”

The results indicate that a 10% increase in spot price uncertainty is associated with 0.9% increase in contract coal prices, and that both risk aversion and relationship-specific investments are important determinants of the coal contracting behavior of US power plants. “This suggests that any empirical analysis of contracting should account for the roles played by both transaction costs and risk aversion,” Jha writes. His estimated effect of spot price uncertainty on contract prices implies that plants are willing to trade off a $1.62 increase in their expected total costs for a $1 decrease in their standard deviation of total costs. “This is far larger than the risk premiums traditionally paid in commodities markets, suggesting that price regulated electric utilities have an especially low tolerance for risk.”

Jha uses his estimate of risk aversion to conduct a simple simulation analysis of the cost-effectiveness of a carbon tax relative to cap and trade.  The inputs to this simulation analysis are plant-level risk aversion, the mean of the permit price, volatility in the permit price, and the correlation between the permit price and the spot coal price. The carbon tax is set equal to the mean permit price, noting that the conditional variance of the carbon tax is equal to zero.  At the central parameter values, the ratio of the aggregate costs incurred by plants under cap and trade relative to the carbon tax is 1.27. When the risk aversion parameter is set to 50% of his estimate, the relative cost-effectiveness ratio is 1.13. This relative cost-effectiveness ratio is thus highly sensitive to the assumed level of risk aversion. He concludes, “The results of my simulation analysis highlight that risk aversion should play an important role in the decision regarding which of these two policy instruments are implemented.”

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JOURNAL

Journal of the Association of Environmental and Resource Economists

DOI

10.1086/715885 

Risky food-finding strategy could be the key to human success

Creative free time may have come from big meals that could be shared

Peer-Reviewed Publication

DUKE UNIVERSITY

 

IMAGE: A GROUP OF HADZA WOMEN SHARE A MEAL OF ROASTED TUBERS. COMBINING HUNTING AND GATHERING WITH FOOD SHARING, GROUP MEMBERS CAN RISK SPENDING A LOT OF ENERGY TO FIND FOOD KNOWING THEY WON’T STARVE IF THEY RETURN TO CAMP EMPTY-HANDED. view more 

CREDIT: HERMAN PONTZER, DUKE UNIVERSITY

DURHAM, N.C. – It’s a cold and rainy Sunday afternoon: would you rather be running after tasteless wild berries, or curled up on your couch with fuzzy socks and a good book?

You might not have had that choice if our ancestors had not taken a big gamble with their food.

A new study published in Science on December 24 shows that early human foragers and farmers adopted an inefficient high-risk, high-reward strategy to find food. They spent more energy in pursuit of food than their great ape cousins, but brought home much more calorie-rich meals that could be shared with the rest of their group. This strategy allowed some to rest or tackle other tasks while food was being acquired.

“Hunting and gathering is risky and inefficient, but the rate of return is enormous,” said study co-leader, Herman Pontzer, an associate professor of Evolutionary Anthropology at Duke University. “We can share our food, and because we got so many calories before noon, we can hang out around each other in this new space, a free-time space.”

Humans spend a lot more energy than great apes. We have big brains that eat up a lot of calories, we live a long time, we can have long pregnancies that produce big babies, and these babies rely on adults for a long time.

To find out how humans obtained this extra energy, a group of researchers led by Thomas Kraft, a postdoctoral researcher at the University of California Santa Barbara, and Pontzer  compared the energy budgets of wild gorillas, chimpanzees and orangutans with that of populations of Tanzanian hunter-gatherers (Hadza) and Bolivian forager-horticulturalists (Tsimane).

Hunter-gatherers and forager-horticulturalists both gather food from wild plants and animals, but the Tsimane also produce small-scale crops.

Energy budgets depend on how much food energy is absorbed, and how much time and energy are spent obtaining food. Humans were thought to maintain their energetically costly lifestyle in one of two ways: they could be super-efficient, spending little time and energy finding food – in part due to the use of tools and technological advances, or they could spend a lot of energy to quickly bring home a lot of food, sacrificing energy efficiency.

The researchers found that hunter-gatherers and forager-horticulturalists are inefficient, high-intensity foragers. Like a gas-guzzling pick-up truck bringing home a ton of donuts, they spend a lot more energy obtaining food than great apes, but they do it faster and the food they obtain is high in calories. Rather than minimizing their costs, they take a risk to maximize their rewards.

Chimpanzees, gorillas and orangutans, on the other hand, are like an electric car bringing home a head of lettuce and some apples. They are essentially herbivores and frugivores who eat very little, if any, meat. Their strategy is one of low risk, low rewards: their food is easy to find, but it’s fibrous, low in energy, and it takes a lot of time to get enough of it.

The Hadza hunter-gatherers and the Tsimane forager-horticulturalists both eat high-calorie foods that are harder to get. They spend a lot of energy hunting, gathering, planting and harvesting, but can quickly bring home a nutritious lunch. What’s more, they bring enough to share.

CAPTION

A group of Hadza women use tools to dig out high-calorie tubers, that they will then roast and share with their group.

CREDIT

Herman Pontzer, Duke University

Pontzer said sharing provides a safety net, enabling some group members to take risks, targeting big game and other high-risk, high-reward foods. If they come home empty-handed, which they often do, they know others will have something to share. The possibility of sharing food also means some group members can even stay at the camp on occasion, enjoying one of our most precious commodities: free time.

“This slight shift in the way that we go about getting our food has fundamentally made everything else possible,” Pontzer said. Free time allows group members to communicate about things other than food. It allows for experimentation, for learning, for creativity, for play, for culture.

Being wired to finding and sharing energy bombs was, and still is, a winning strategy for hunter-gatherers and foragers-horticulturalists, Pontzer said. But it also can be treacherous for those of us with a pantry full of delicious highly caloric food.

“We are built to try and get a lot of food,” Pontzer said. “We are hugely ravenous and inefficient, and that's how we've evolved for 2 million years.”

“That doesn’t mean we can be careless with our energy today, and it doesn't mean that we have to say, ‘well there's nothing we can do about it’,” Pontzer said. “We have to be aware of ourselves and our evolutionary history.”

This research was Supported by the National Science Foundation (BCS0422690, BCS-0850815, BCS-1440867, BCS-1062879, BCS-1440841, BCS-1440671, BCS-0242455), NIH (R01AG024119, R56AG024119), the Leakey Foundation, the Max Planck Institute for Evolutionary Anthropology, the University of California, San Diego, and the American School of Prehistoric Research (Harvard University), as well as IAST funding from ANR under grant ANR-17-EUR-0010 (Investissements d’Avenir program).

CITATION: “The Energetics of Uniquely Human Subsistence Strategies,” Thomas S. Kraft,  Vivek V. Venkataraman, Ian J. Wallace, Alyssa N. Crittenden, Nicholas B. Holowka, Jonathan Stieglitz, Jacob Harris, David A. Raichlen, Brian Wood, Michael Gurven, Herman Pontzer. Science, 374 (6575), eabf0130. Decemer 2021. DOI: 10.1126/science.abf0130

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JOURNAL

Science

DOI

10.1126/science.abf0130 

SIRT2: another important factor that determines the toxic effects and potential mechanisms of PM2.5

Peer-Reviewed Publication

HIGHER EDUCATION PRESS

 

VIDEO: SIRT2: ANOTHER IMPORTANT FACTOR THAT DETERMINES THE TOXIC EFFECTS AND POTENTIAL MECHANISMS OF PM2.5 view more 

CREDIT: HIGHER EDUCATION PRESS LIMITED COMPANY

Air pollutants comprise a complex mixture of airborne particles such as gases, liquids, and particulate matter (PM). Particulate matter 2.5 (PM2.5) refers to fine particles with aerodynamic equivalent diameter less than or equal to 2.5 μm in ambient air. It is one of the most harmful air pollutants that can be deposited in bronchi and alveoli through inhalation. Moreover, PM2.5 can even penetrate the air–blood barrier into the blood circulation. Epidemiological studies have shown a relationship between PM2.5 exposure and adverse health outcomes, including respiratory diseases, cardiovascular diseases, type 2 diabetes, and autoimmune diseases. Nevertheless, the mechanisms underlying PM2.5-induced airway inflammation remain largely unexplored. Fourth Military Medical University professor Qiong Wang and Heng Ma provide a novel mechanism underlying PM2.5-induced airway inflammation and bronchial hyperresponsiveness. This study entitled “Particulate matter 2.5 triggers airway inflammation and bronchial hyperresponsiveness in mice by activating the SIRT2–p65 pathway" is published in Frontiers of Medicine on Nov. 2021.

In this study, PM2.5 exposure was found to trigger airway inflammation and bronchial hyperresponsiveness. Mechanistically, PM2.5 exposure lowered the expression and activity of SIRT2 in bronchial tissues. Notably, SIRT2 directly interacted with p65 and regulated the phosphorylation and acetylation activation of p65 to initiate the NF-κB signaling pathway and airway inflammation. Thereafter, the airway inflammation induced thickening in the bronchial smooth muscle layer and basement membrane layer, increased goblet cell proliferation and mucus secretion, tracheal stenosis, and bronchial hyperresponsiveness. Meanwhile, p65 phosphorylation and acetylation, airway inflammation, and bronchial hyperresponsiveness were deteriorated in SIRT2 knockout mice exposed to PM2.5. Importantly, we found that triptolide, an inhibitor of p65, significantly inhibited PM2.5-induced p65 phosphorylation and acetylation, thereby reducing airway inflammation and bronchial hyperresponsiveness.

This study demonstrated that the SIRT2-p65 signaling pathway is a novel mechanism responsible for PM2.5-induced organ damage, therefore providing a scientific basis and promising therapeutic and prevention strategies against PM2.5-induced toxicity.

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About Higher Education Press

Founded in May 1954, Higher Education Press Limited Company (HEP), affiliated with the Ministry of Education, is one of the earliest institutions committed to educational publishing after the establishment of P.R.China in 1949. After striving for six decades, HEP has developed into a major comprehensive publisher, with products in various forms and at different levels. Both for import and export, HEP has been striving to fill in the gap of domestic and foreign markets and meet the demand of global customers by collaborating with more than 200 partners throughout the world and selling products and services in 32 languages globally. Now, HEP ranks among China's top publishers in terms of copyright export volume and the world's top 50 largest publishing enterprises in terms of comprehensive strength.

The Frontiers Journals series published by HEP includes 28 English academic journals, covering the largest academic fields in China at present. Among the series, 13 have been indexed by SCI, 6 by EI, 2 by MEDLINE, 1 by A&HCI. HEP's academic monographs have won about 300 different kinds of publishing funds and awards both at home and abroad.

About Frontiers of Medicine

Frontiers of Medicine is oriented to an international peer-reviewed journal of general medicine that captures the best science from the diverse medical disciplines and relevant fields encompassing different aspects of life sciences. The Editors-in-Chief are Academician Saijuan Chen, Shanghai Institute of Hematology, Ruijin Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China; Academician Boli Zhang, Tianjin University of Traditional Chinese Medicine, Tianjin, China; Academician Baofeng Yang; Harbin Medical University, Harbin, China; Academician Xiaoping Chen, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China. The main topics include clinical medicine, basic medical sciences, epidemiology, translational research, traditional Chinese medicine, public health, and health policies. The journal has been indexed by SCI, MEDLINE, SCOPUS, Source Journals for Chinese Scientific and Technical Papers and Citations, CSCD, etc.

 

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JOURNAL

Frontiers in Medicine

DOI

10.1007/s11684-021-0839-4 

METHOD OF RESEARCH

Experimental study

SUBJECT OF RESEARCH

Animals

ARTICLE TITLE

Particulate matter 2.5 triggers airway inflammation and bronchial hyperresponsiveness in mice by activating the SIRT2-p65 pathway