More carbon in the ocean can lead to smaller fish

UNIVERSITY OF CONNECTICUT

 

As humans continue to send large quantities of carbon into the atmosphere, much of that carbon is absorbed by the ocean, and UConn researchers have found high CO2 concentrations in water can make fish grow smaller.

Researchers Christopher Murray PhD '19, now at the University of Washington, and UConn Associate Professor of Marine Sciences Hannes Baumann have published their findings in PLOS ONE.

"The ocean takes up quite a bit of CO2. Estimates are that it takes up about one-third to one-half of all CO2 emissions to date," says Murray. "It does a fantastic job of buffering the atmosphere but the consequence is ocean acidification."

Life relies on chemical reactions and even a slight change in pH can impede the normal physiological functions of some marine organisms; therefore, the ocean's buffering effect may be good for land-dwellers, but not so good for ocean inhabitants.

Baumann explains that in the study of ocean acidification (or OA), researchers have tended to assume fish are too mobile and tolerant of heightened CO2 levels to be adversely impacted.

"Fish are really active, robust animals with fantastic acid/base regulatory capacity," says Murray. "So when OA was emerging as a major ocean stressor, the assumption was that fish are going to be OK, [since] they are not like bivalves or sea urchins or some of the other animals showing early sensitivities."

The research needed for drawing such conclusions requires long-term studies that measure potential differences between test conditions. With fish, this is no easy task, says Baumann, largely due to logistical difficulties in rearing fish in laboratory settings.

"For instance, many previous experiments may not have seen the adverse effects on fish growth, because they incidentally have given fish larvae too much food. This is often done to keep these fragile little larvae alive, but the problem is that fish may eat their way out of trouble -- they overcompensate - so you come away from your experiment thinking that fish growth is no different under future ocean conditions," says Baumann.

In other words, if fish are consuming more calories because their bodies are working harder to cope with stressors like high CO2 levels, a large food ration would mask any growth deficits.

Additionally, previous studies that concluded fish are not impacted by high CO2 levels involved long-lived species of commercial interest. Baumann and Murray overcame this hurdle by using a small, shorter-lived fish called the Atlantic silverside so they could study the fish across its life cycle. They conducted several independent experiments over the course of three years. The fish were reared under controlled conditions from the moment the eggs were fertilized until they were about 4 months old to see if there were cumulative effects of living in higher CO2 conditions.

Murray explains, "We tested two CO2 levels, present-day levels and the maximum level of CO2 we would see in the ocean in 300 years under a worst-case emissions scenario. The caveat to that is that silversides spawn and develop as larvae and early juveniles in coastal systems that are prone to biochemical swings in CO2 and therefore the fish are well-adapted to these swings."

The maximum CO2 level applied in the experiments is one aspect that makes this research novel, says Murray,

"That is another important difference between our study and other studies that focus on long-term effects; almost all studies to date have used a lower CO2 level that corresponds with predictions for the global ocean at the end of this century, while we applied this maximum level. So it is not surprising that other studies that used longer-lived animals during relatively short durations have not really found any effects. We used levels that are relevant for the environment where our experimental species actually occurs."

Baumann and Murray hypothesized that there would be small, yet cumulative, effects to measure. They also expected fish living in sub-ideal temperatures would experience more stress related to the high CO2 concentrations and that female fish would experience the greatest growth deficits.

The researchers also used the opportunity to study if there were sex-determination impacts on the population in the varying CO2 conditions. Sex-determination in Atlantic silversides depends on temperature, but the influence of seawater pH is unknown. In some freshwater fish, low pH conditions produce more males in the population. However, they did not find any evidence of the high CO2 levels impacting sex differentiation in the population. And the growth males and females appeared to be equally affected by high CO2.

"What we found is a pretty consistent response in that if you rear these fish under ideal conditions and feed them pretty controlled amounts of food, not over-feeding them, high CO2 conditions do reduce their growth in measurable amounts," says Murray.

They found a growth deficit of between five and ten percent, which Murray says amounts to only a few millimeters overall, but the results are consistent. The fish living at less ideal temperatures and more CO2 experienced greater reductions in growth.

Murray concludes that by addressing potential shortcomings of previous studies, the data are clear: "Previous studies have probably underestimated the effects on fish growth. What our paper is demonstrating is that indeed if you expose these fish to high CO2 for a significant part of their life cycle, there is a measurable reduction in their growth. This is the most important finding of the paper."

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This work was funded by the National Science Foundation grant number OCE #1536165. You can follow the researchers on Twitter @baumannlab1 and @CMurray187.

'Price of life' lowest in UK during COVID-19 pandemic, study finds

UNIVERSITY OF EXETER

 

The price the UK government was prepared to pay to save lives during the COVID-19 pandemic was far lower than in many other developed nations, a study has revealed.

In a cross-country comparison across nine nations - Belgium, the US, Germany, Korea, Italy, Denmark, China, New Zealand and the UK - researchers used epidemiological modelling to calculate how many lives were lost through delaying lockdown, estimating that a UK lockdown date just three days earlier would have saved 20,000 lives.

They then linked those policy decisions to the financial cost lockdown had on GDP, resulting in a 'price of life' estimate - the amount of money governments were willing to pay to protect their citizens' lives, reflected in the economic activity sacrificed.

The price of life in the UK was among the lowest at around $100,000, and lower still once under-reporting of COVID-19 deaths is accounted for. In contrast countries that were quicker to go into lockdown, such as Germany, New Zealand and South Korea, put a price on life in excess of $1million.

"Price of life estimates are of critical importance given that government intervention has the ability to save life, yet trades off against other goods," said lead author Ben Balmford, from the University of Exeter Business School.

"Comparing across countries those who pursued an early lockdown strategy reveal themselves to be willing to pay a high price to save their citizen's lives, only rejecting prices above $1m.

"However, some countries, those which imposed lockdown relatively late-on in their respective pandemics, were clearly only willing to pay far less."

The study addressed why countries have suffered such huge variations in death tolls and established how the timing of lockdowns impacted on mortality rates, complementing the official Covid-19 statistics with excess mortality data and taking into account socio-economic and demographic factors such as age, population density and income inequality.

Modelling mortality across the countries before simulating changes in the date of lockdown, the researchers calculated that 20,000 lives in the UK would have been saved by imposing lockdown three days earlier.

Even further delays would have cost yet more lives: 32,000 extra people would have died had lockdown come in three days later than it did; while a delay of 12 days would have cost more than 200,000 extra lives.

Similarly high figures were observed in other countries that acted relatively late - such as Italy - highlighting how earlier governmental action would have saved many more lives.

Price of life was then calculated using estimates of the financial cost of lockdown on GDP, comparing IMF forecasts pre-lockdown to the most recent figures and teasing apart the amount of GDP loss that comes from the effects of lockdown policy, as opposed to other factors.

Imposing lockdown earlier on in a country's outbreak means saving more lives, but at a higher cost to the economy. This means countries that delayed their lockdowns such as the UK, US and Italy are revealed to price the lives of their citizens relatively low (at around $100,000) whereas the price of life in Germany, a country very similar to the UK in terms of GDP per capita, was $1.03m - around an order of magnitude higher.

For those countries whose governments acted quickest - South Korea and New Zealand - and whose response to date has been deemed most successful, the price of life was $6.7m and $11.6m respectively.

"Seemingly, much like a bird in the hand, cash flowing through the market is worth much more than value passing through wellbeing, at least to some countries," said Balmford.

"By choosing not to impose lockdowns three days earlier, governments rejected saving more lives when the price was relatively high.

"The same logic reveals them to have accepted the implied price of life from a delay - they would rather bear the cost in terms of GDP than as further human lives lost."

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The study is published in the journal Environmental and Resource Economics.

Study suggests optimal social networks of no more than 150 people

U.S. ARMY RESEARCH LABORATORY

 

RESEARCH TRIANGLE PARK, N.C. -- New rules of engagement on the battlefield will require a deep understanding of networks and how they operate according to new Army research. Researchers confirmed a theory that find that networks of no more than 150 are optimal for efficient information exchange.

"This is the beginning of a new way to address competition and conflict in today's complex world," said Dr. Bruce West, senior scientist, Army Research Office, an element of the U.S. Army Combat Capabilities Development Command's Army Research Laboratory. "To increase the utility of the Army's evolving network structures in terms of robustness, resilience, adaptability and efficiency, requires a deeper understanding of how networks actually function, both ours and those of our adversary."

Researchers at ARO and the University of North Texas tested a theory proposed by British anthropologist Robin Dunbar in the 1990s, which suggested that 150 was the largest group that humans can maintain stable social relations. In the vicinity of this size the social group becomes unstable and splinters into smaller groups.

"It takes a network to defeat a network," wrote retired Army Gen. Stanley McChrystal, in his book Team of Teams. He discusses understanding the implications of the theory, abstracting from battlefield experiences in Iraq battling the loosely networked but effective terrorist organization Al Qaeda.

Researchers published their findings in the peer-reviewed Proceedings of the National Academy of Sciences of the United States of America. In their study, they prove Dunbar's conjecture, demonstrating that certain sized network has better information transport properties than others, and that networks of no more than 150 are optimal for internally sharing information.

"A fundamental property of a network is the relation between its functionality and size, which is why understanding the source of the Dunbar Number is important," said West, a co-author of the paper.

The researchers propose that the number 150 arises as a consequence of internal dynamics of a complex network self-organizing within a social system.

Based on that theory, the researchers also indicated that a peaceful demonstration can be turned into a mob by just a few agitators, with the size of 150 being the most vulnerable to such disruption.

"The 150 optimum has been observed by Dunbar and others, but Dr. West and colleagues are the first to computationally capture the theorized process of information dynamics, which are fundamental to problem-solving, development of group factions, and formation of cohesive groups," said Dr. Lisa Troyer, who manages ARO's social and behavioral sciences research program. "This is an important leap forward by for social science theory and will likely lead to further research and insights on collective action."

Dunbar predicted that social groups have optimal sizes. He referred to these group sizes as nested layering and that they have a scaling ratio of approximately three. Consequently, he identified the sequence of sizes of cognitively efficient social groups 5, 15, 50, 150 and 500, explaining that these layers were not equal in terms of strength of relationships.

"The layering sequence is interesting because each number in the sequence is within a factor of two of the empirical magnitudes of entity sizes in the U.S. Army, ranging from a squad of roughly 15 to a platoon of approximately three times the squad size, next to a company consisting of three platoons and followed by a brigade the size of roughly three companies and so on," West said. "This is the intuition on which armies have been hierarchically constructed by military leaders since the Roman Empire."

According to West, understanding how information flows within, is analyzed by, and is accepted or rejected from groups of various sizes is crucial in the training of teams. He said that this is not only true in the development of a single team, but is just as important for the training of teams to work together, to form teams-of-teams.

"The size of a team may be the determining factor in the potential success of a complex mission that depends on adaptability and collective problem solving," West said. "The same understanding can be applied to the reverse process, that of insinuating disinformation within an adversarial group. The size of the group may at times be more important than the form the lie takes for its acceptance and immediate transmission, witness the recent riots."

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CCDC Army Research Laboratory is an element of the U.S. Army Combat Capabilities Development Command. As the Army's corporate research laboratory, ARL discovers, innovates and transitions science and technology to ensure dominant strategic land power. Through collaboration across the command's core technical competencies, CCDC leads in the discovery, development and delivery of the technology-based capabilities required to make Soldiers more lethal to win the nation's wars and come home safely. CCDC is a major subordinate command of the U.S. Army Futures Command.

Dozens of pesticides linked with mammary gland tumors in animal studies

Findings have implications for how federal agencies assess pesticides for breast cancer risk

SILENT SPRING INSTITUTE

In an analysis of how regulators review pesticides for their potential to cause cancer, researchers at Silent Spring Institute identified more than two dozen registered pesticides that were linked with mammary gland tumors in animal studies. The new findings raise concerns about how the US Environmental Protection Agency (EPA) approves pesticides for use and the role of certain pesticides in the development of breast cancer.

Several years ago, a resident on Cape Cod in Massachusetts contacted researchers at Silent Spring looking for information on an herbicide called triclopyr. Utility companies were looking to spray the chemical below power lines on the Cape to control vegetation.

"We know pesticides like DDT increase breast cancer risk, so we decided to look into it," says co-author Ruthann Rudel, an environmental toxicologist and director of research at Silent Spring. "After examining pesticide registration documents from EPA, we found two separate studies in which rodents developed mammary gland tumors after being exposed to triclopyr, yet for some reason regulators dismissed the information in their decision not to treat it as a carcinogen."

When manufacturers apply to register a pesticide, EPA reviews existing studies and based on those studies assigns the chemical a cancer classification--for instance, how likely or unlikely the chemical is to cause cancer. After reviewing triclopyr, Silent Spring researchers wondered if evidence of mammary tumors was being ignored for other pesticides as well.

Reporting in the journal Molecular and Cellular Endocrinology, Rudel and Silent Spring scientist Bethsaida Cardona reviewed more than 400 EPA pesticide documents summarizing the health effects of each registered pesticide. They found a total of 28 pesticides linked with mammary gland tumors, yet EPA acknowledged only nine of them as causing mammary tumors and dismissed the evidence entirely for the remaining 19.

Rudel and Cardona also found that many of the pesticides in their analysis behaved like endocrine disruptors, for instance, by interfering with estrogen and progesterone. "Breast cancer is highly influenced by reproductive hormones, which stimulate the proliferation of cells within the breast, making it more susceptible to tumors," says Rudel. "So, it's important that regulators consider this kind of evidence. If they don't, they risk exposing people to pesticides that are breast carcinogens."

Traditionally, toxicologists focus on whether a chemical causes DNA damage when determining its potential to cause cancer. But recent findings in cancer biology show there are many ways chemicals can trigger the development of cancer. For example, chemicals can suppress the immune system, cause chronic inflammation, or disrupt the body's system of hormones, all of which can lead to the growth of breast tumors and other types of tumors as well.

"In light of our findings, we hope EPA updates its guidelines for assessing mammary gland tumors by considering evidence that more completely captures the biology of breast cancer, such as the effects of endocrine disruptors," says Cardona.

Rudel and Cardona recommend that EPA re-evaluate five pesticides in particular--IPBC, triclopyr, malathion, atrazine and propylene oxide--due to their widespread use and the evidence uncovered in the new analysis. IPBC is a preservative in cosmetics; triclopyr is an agricultural herbicide that is also used to control vegetation growth along rights-of-way; malathion is a common residential and agricultural pesticide and is used in some lice treatments; atrazine is one of the most commonly-used herbicides in agriculture; and propylene oxide is used to preserve food, cosmetics, and pharmaceuticals, and has many similarities with ethylene oxide, a known human carcinogen.

The project is part of Silent Spring Institute's Safer Chemicals Program which is developing new cost-effective ways of screening chemicals for their effects on the breast. Knowledge generated by this effort will help government agencies regulate chemicals more effectively and assist companies in developing safer products.

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Funding for this project was provided by the National Institute of Environmental Health Sciences (NIEHS) Breast Cancer and the Environment Research Program (award number U01ES026130), the Cedar Tree Foundation, and Silent Spring Institute's Innovation Fund. The project was also supported by an NIEHS T32 Transdisciplinary Training at the Intersection of Environmental Health and Social Science grant (award number 1T32ES023769-01A1).

Reference:

Cardona, B. and R.A. Rudel. 2020. US EPA's regulatory pesticide evaluations need clearer guidelines for considering mammary gland tumors and other mammary gland effects. Molecular and Cellular Endocrinology. DOI: 10.1016/j.mce.2020.110927

About Silent Spring Institute:

Silent Spring Institute, located in Newton, Mass., is the leading scientific research organization dedicated to uncovering the link between chemicals in our everyday environments and women's health, with a focus on breast cancer prevention. Founded in 1994, the institute is developing innovative tools to accelerate the transition to safer chemicals, while translating its science into policies that protect health. Visit us at http://www.silentspring.org and follow us on Twitter @SilentSpringIns.

Surprisingly dense exoplanet challenges planet formation theories

Small telescope and inexpensive diffuser key to results

ASSOCIATION OF UNIVERSITIES FOR RESEARCH IN ASTRONOMY (AURA)

 

IMAGE: NEW DETAILED OBSERVATIONS WITH NSF'S NOIRLAB FACILITIES REVEAL A YOUNG EXOPLANET, ORBITING A YOUNG STAR IN THE HYADES CLUSTER, THAT IS UNUSUALLY DENSE FOR ITS SIZE AND AGE. SLIGHTLY SMALLER... view more 

CREDIT: NOIRLAB/NSF/AURA/J. POLLARD

New detailed observations with NSF's NOIRLab facilities reveal a young exoplanet, orbiting a young star in the Hyades cluster, that is unusually dense for its size and age. Weighing in at 25 Earth-masses, and slightly smaller than Neptune, this exoplanet's existence is at odds with the predictions of leading planet formation theories.

New observations of the exoplanet, known as K2-25b, made with the WIYN 0.9-meter Telescope at Kitt Peak National Observatory (KPNO), a Program of NSF's NOIRLab, the Hobby-Eberly Telescope at McDonald Observatory and other facilities, raise new questions about current theories of planet formation [1]. The exoplanet has been found to be unusually dense for its size and age -- raising the question of how it came to exist. Details of the findings appear in The Astronomical Journal.

Slightly smaller than Neptune, K2-25b orbits an M-dwarf star -- the most common type of star in the galaxy -- in 3.5 days. The planetary system is a member of the Hyades star cluster, a nearby cluster of young stars in the direction of the constellation Taurus. The system is approximately 600 million years old, and is located about 150 light-years from Earth.

Planets with sizes between those of Earth and Neptune are common companions to stars in the Milky Way, despite the fact that no such planets are found in our Solar System. Understanding how these "sub-Neptune" planets form and evolve is a frontier question in studies of exoplanets.

Astronomers predict that giant planets form by first assembling a modest rock-ice core of 5-10 times the mass of Earth and then enrobing themselves in a massive gaseous envelope hundreds of times the mass of Earth. The result is a gas giant like Jupiter. K2-25b breaks all the rules of this conventional picture: with a mass 25 times that of Earth and modest in size, K2-25b is nearly all core and very little gaseous envelope. These strange properties pose two puzzles for astronomers. First, how did K2-25b assemble such a large core, many times the 5-10 Earth-mass limit predicted by theory? [2] And second, with its high core mass -- and consequent strong gravitational pull -- how did it avoid accumulating a significant gaseous envelope?

The team studying K2-25b found the result surprising. "K2-25b is unusual," said Gudmundur Stefansson, a postdoctoral fellow at Princeton University, who led the research team. According to Stefansson, the exoplanet is smaller in size than Neptune but about 1.5 times more massive. "The planet is dense for its size and age, in contrast to other young, sub-Neptune-sized planets that orbit close to their host star," said Stefansson. "Usually these worlds are observed to have low densities -- and some even have extended evaporating atmospheres. K2-25b, with the measurements in hand, seems to have a dense core, either rocky or water-rich, with a thin envelope."

To explore the nature and origin of K2-25b, astronomers determined its mass and density. Although the exoplanet's size was initially measured with NASA's Kepler satellite, the size measurement was refined using high-precision measurements from the WIYN 0.9-meter Telescope at KPNO and the 3.5-meter telescope at Apache Point Observatory (APO) in New Mexico. The observations made with these two telescopes took advantage of a simple but effective technique that was developed as part of Stefansson's doctoral thesis. The technique uses a clever optical component called an Engineered Diffuser, which can be obtained off the shelf for around $500. It spreads out the light from the star to cover more pixels on the camera, allowing the brightness of the star during the planet's transit to be more accurately measured, and resulting in a higher-precision measurement of the size of the orbiting planet, among other parameters [3].

"The innovative diffuser allowed us to better define the shape of the transit and thereby further constrain the size, density and composition of the planet," said Jayadev Rajagopal, an astronomer at NOIRLab who was also involved in the study.

For its low cost, the diffuser delivers an outsized scientific return. "Smaller aperture telescopes, when equipped with state-of-the-art, but inexpensive, equipment can be platforms for high impact science programs," explains Rajagopal. "Very accurate photometry will be in demand for exploring host stars and planets in tandem with space missions and larger apertures from the ground, and this is an illustration of the role that a modest-sized 0.9-meter telescope can play in that effort."

Thanks to the observations with the diffusers available on the WIYN 0.9-meter and APO 3.5-meter telescopes, astronomers are now able to predict with greater precision when K2-25b will transit its host star. Whereas before transits could only be predicted with a timing precision of 30-40 minutes, they are now known with a precision of 20 seconds. The improvement is critical to planning follow-up observations with facilities such as the international Gemini Observatory and the James Webb Space Telescope[4].

Many of the authors of this study are also involved in another exoplanet-hunting project at KPNO: the NEID spectrometer on the WIYN 3.5-meter Telescope. NEID enables astronomers to measure the motion of nearby stars with extreme precision -- roughly three times better than the previous generation of state-of-the-art instruments -- allowing them to detect, determine the mass of, and characterize exoplanets as small as Earth.

Notes

[1] The planet was originally detected by Kepler in 2016. Detailed observations for this study were made using the Habitable-zone Planet Finder on the 11-meter Hobby-Eberly Telescope at McDonald Observatory.

[2] The prediction from theory is that once planets have formed a core of 5-10 Earth-masses they begin to accrete gas instead: very little rocky material is added after that.

[3] Diffusers were first used for exoplanet observations in 2017.

[4] GHOST, on Gemini South, will be used to carry out transit spectroscopy of exoplanets found by Kepler and TESS. Their target list includes the star K2-25.

More information

This research was presented in a paper to appear in The Astronomical Journal.

The team is composed of Gudmundur Stefansson (The Pennsylvania State University and Princeton University), Suvrath Mahadevan (The Pennsylvania State University), Marissa Maney (The Pennsylvania State University), Joe P. Ninan (The Pennsylvania State University), Paul Robertson (University of California, Irvine), Jayadev Rajagopal (NSF's NOIRLab), Flynn Haase (NSF's NOIRLab), Lori Allen (NSF's NOIRLab), Eric B. Ford (The Pennsylvania State University), Joshua Winn (Princeton), Angie Wolfgang (The Pennsylvania State University), Rebekah I. Dawson (The Pennsylvania State University), John Wisniewski (University of Oklahoma), Chad F. Bender (University of Arizona), Caleb Cañas (The Pennsylvania State University), William Cochran (The University of Texas at Austin), Scott A. Diddams (National Institute of Standards and Technology, and University of Colorado), Connor Fredrick (National Institute of Standards and Technology, and University of Colorado), Samuel Halverson (Jet Propulsion Laboratory), Fred Hearty (The Pennsylvania State University), Leslie Hebb (Hobart and William Smith Colleges), Shubham Kanodia (The Pennsylvania State University), Eric Levi (The Pennsylvania State University), Andrew J. Metcalf (Air Force Research Laboratory, National Institute of Standards and Technology, and University of Colorado), Andrew Monson (The Pennsylvania State University), Lawrence Ramsey (The Pennsylvania State University), Arpita Roy (California Institute of Technology), Christian Schwab (Macquarie University), Ryan Terrien (Carleton College), and Jason T. Wright (The Pennsylvania State University).

NSF's National Optical-Infrared Astronomy Research Laboratory (NOIRLab), the US center for ground-based optical-infrared astronomy, operates the international Gemini Observatory (a facility of NSF, NRC-Canada, ANID-Chile, MCTIC-Brazil, MINCyT-Argentina, and KASI-Republic of Korea), Kitt Peak National Observatory (KPNO), Cerro Tololo Inter-American Observatory (CTIO), the Community Science and Data Center (CSDC), and the Vera C. Rubin Observatory. It is managed by the Association of Universities for Research in Astronomy (AURA) under a cooperative agreement with NSF and is headquartered in Tucson, Arizona. The astronomical community is honored to have the opportunity to conduct astronomical research on Iolkam Du'ag (Kitt Peak) in Arizona, on Maunakea in Hawaiʻi, and on Cerro Tololo and Cerro Pachón in Chile. We recognize and acknowledge the very significant cultural role and reverence that these sites have to the Tohono O'odham Nation, to the Native Hawaiian community, and to the local communities in Chile, respectively.

The WIYN 0.9-meter Telescope is founded on a partnership between the WIYN Consortium, led by the University of Wisconsin-Madison and Indiana University, and the NSF's NOIRLab. Its operations include an international group of universities.

Links

• Research paper
• Penn State University release
• McDonald Observatory release

Studies shed new light on how biodiversity influences plant decay

Two independent studies exploring how biodiversity impacts plant decay in forests worldwide could help predict the potential effect of species loss on ecosystems

ELIFE

IMAGE: SCIENTISTS HAVE PROVIDED NEW INSIGHTS ON THE RELATIONSHIP BETWEEN PLANT DIVERSITY IN FORESTS AND THE DIVERSITY OF ORGANISMS INVOLVED IN THEIR DECAY, SUCH AS BACTERIA AND FUNGI. view more 

CREDIT: LÉA BEAUMELLE (CC BY 4.0)

Scientists have provided new insights on the relationship between plant diversity in forests and the diversity of organisms involved in their decay, such as bacteria and fungi.

Plant litter decomposition is a major ecosystem function, linking plant biomass to carbon stocks in the soil and atmosphere, and releasing nutrients including nitrogen and phosphorus that influence soil biodiversity. Two new independent studies, published today in eLife, report how plant biodiversity impacts decomposition processes and could help predict how the loss of species might affect forest ecosystems.

For the first study, researchers based in China and France analysed the relationship between the diversity of plant litter and decomposition across 65 field studies in forests around the world. Their results show that plant decomposition is faster when litter is composed of more than one species. This was particularly clear in forests with mild temperatures, but were more variable in other forest environments.

"We also found that plant diversity accelerated the release of nitrogen, but not phosphorus, potentially indicating a shift in ecosystem nutrient limitation caused by a change in biodiversity," explains joint first author Liang Kou, Associate Professor at the Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, China. "This discovery was again clear for temperate forests, but still needs confirmation for boreal, Mediterranean, subtropical and tropical forests that are currently limited on data."

"Our results suggest that biodiversity loss will modify carbon and nutrient cycling in forest ecosystems," adds joint senior author Huimin Wang, Professor at the Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences. "The potential impact of changes in litter diversity on carbon and nutrient cycling warrants particular attention in future studies, which would ideally integrate responses from decomposers for a better understanding of changes in carbon and nutrient cycling and the mechanisms driving them."

The second study in eLife, from researchers based in Germany and Belgium, similarly highlights the important links between plant litter and decomposer diversity, but it also shows how these links can be influenced by human activity.

"Industrial and agricultural activities can have detrimental effects on decomposer organisms," says first author Léa Beaumelle, a postdoctoral researcher at the German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, University of Leipzig, Germany. "They release chemical stressors such as metals and pesticides, as well as nutrients, into soil and water. Chemical stressors and added nutrients modify decomposer communities by affecting their diversity, abundance and metabolism."

Previous experiments conducted in simplified conditions have shown that biodiversity loss has detrimental effects on ecosystem processes. But how these results apply to real-world scenarios of change in biodiversity remains unclear. The researchers set out to discover if the responses of plant litter decomposition to chemical stressors and added nutrients can be explained by changes in decomposer diversity across ecosystems.

To do this, the team analysed the results of 69 independent studies that reported 660 observations of the effects of chemical stressors or nutrient enrichment on animal and microbial decomposers and on plant litter decomposition. They found that declines in the diversity and abundance of decomposers explained reductions in plant decay rates under the influence of chemical stressors, but not added nutrients. This suggests that human activities decrease decomposer biodiversity, which then leads to significant effects on ecosystem functions.

"These findings could inform the design of suitable strategies to maintain biodiversity and ecosystem functioning," concludes senior author Nico Eisenhauer, Head of Experimental Interaction Ecology at the German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, University of Leipzig. "But they also show that these strategies must take human activities into account and cannot rely solely on improving biodiversity alone."

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References

The papers 'Diversity-decomposition relationships in forests worldwide' and 'Biodiversity mediates the effects of stressors but not nutrients on litter decomposition' can be freely accessed online at https://doi.org/10.7554/eLife.55813 and https://doi.org/10.7554/eLife.55659, respectively. Contents, including text, figures and data, are free to reuse under a CC BY 4.0 license.

Media contact

Emily Packer, Senior Press Officer
eLife
e.packer@elifesciences.org
01223 855373

About eLife

eLife is a non-profit organisation created by funders and led by researchers. Our mission is to accelerate discovery by operating a platform for research communication that encourages and recognises the most responsible behaviours. We work across three major areas: publishing, technology and research culture. We aim to publish work of the highest standards and importance in all areas of biology and medicine, including Ecology, while exploring creative new ways to improve how research is assessed and published. We also invest in open-source technology innovation to modernise the infrastructure for science publishing and improve online tools for sharing, using and interacting with new results. eLife receives financial support and strategic guidance from the Howard Hughes Medical Institute, the Knut and Alice Wallenberg Foundation, the Max Planck Society and Wellcome. Learn more at https://elifesciences.org/about.

To read the latest Ecology research published in eLife, visit https://elifesciences.org/subjects/ecology.

AI may offer a better way to ID drug-resistant superbugs

Machine learning algorithm uses high-temporal-resolution growth curves to identify pathogens with 98% accuracy and predict antibiotic resistance just as well as genetic-based methods

DUKE UNIVERSITY

 

IMAGE: A NEW METHOD FOR IDENTIFYING STRAINS OF BACTERIA AND GUESSING THEIR RESISTANCE TO ANTIBIOTICS USES AN AI MODEL TO ANALYZE THEIR GROWTH DYNAMICS IN CULTURE. view more 

CREDIT: DUKE UNIVERSITY

Biomedical engineers at Duke University have shown that different strains of the same bacterial pathogen can be distinguished by a machine learning analysis of their growth dynamics alone, which can then also accurately predict other traits such as resistance to antibiotics. The demonstration could point to methods for identifying diseases and predicting their behaviors that are faster, simpler, less expensive and more accurate than current standard techniques.

The results appear online on August 3 in the Proceedings of the National Academy of Sciences.

For most of the history of microbiology, bacteria identification has relied on growing cultures and analyzing the physical traits and behaviors of the resulting bacterial colony. It wasn't until recently that scientists could simply run a genetic test.

Genetic sequencing, however, isn't universally available and can often take a long time. And even with the ability to sequence entire genomes, it can be difficult to tie specific genetic variations to different behaviors in the real world.

For example, even though researchers know the genetic mutations that help shield/protect bacteria from beta-lactam antibiotics--the most commonly used antibiotic in the world--sometimes the DNA isn't the whole story. While a single resistant bacteria usually can't survive a dose of antibiotics on its own, large populations often can.

Lingchong You, professor of biomedical engineering at Duke, and his graduate student, Carolyn Zhang, wondered if a new twist on older methods might work better. Maybe they could amplify one specific physical characteristic and use it to not only identify the pathogen, but to make an educated guess about other traits such as antibiotic resistance.

"We thought that the slight variance in the genes between strains of bacteria might have a subtle effect on their metabolism," You said. "But because bacterial growth is exponential, that subtle effect could be amplified enough for us to take advantage of it. To me, that notion is somewhat intuitive, but I was surprised at how well it actually worked."

How quickly a bacterial culture grows in a laboratory depends on the richness of the media it is growing in and its chemical environment. But as the population grows, the culture consumes nutrients and produces chemical byproducts. Even if different strains start with the exact same environmental conditions, subtle differences in how they grow and influence their surroundings accumulate over time.

In the study, You and Zhang took more than 200 strains of bacterial pathogens, most of which were variations of E. coli, put them into identical growth environments, and carefully measured their population density as it increased. Because of their slight genetic differences, the cultures grew in fits and starts, each possessing a unique temporal fluctuation pattern. The researchers then fed the growth dynamics data into a machine learning program, which taught itself to identify and match the growth profiles to the different strains.

To their surprise, it worked really well.

"Using growth data from only one initial condition, the model was able to identify a particular strain with more than 92 percent accuracy," You said. "And when we used four different starting environments instead of one, that accuracy rose to about 98 percent."

Taking this idea one step further, You and Zhang then looked to see if they could use growth dynamic profiles to predict another phenotype--antibiotic resistance.

The researchers once again loaded a machine learning program with the growth dynamic profiles from all but one of the various strains, along with data about their resilience to four different antibiotics. They then tested to see if the resulting model could predict the final strain's antibiotic resistances from its growth profile. To bulk up their dataset, they repeated this process for all of the other strains.

The results showed that the growth dynamic profile alone could successfully predict a strain's resistance to antibiotics 60 to 75 percent of the time.

"This is actually on par or better than some of the current techniques in the literature, including many that use genetic sequencing data," said You. "And this was just a proof of principle. We believe that with higher-resolution data of the growth dynamics, we could do an even better job in the long term."

The researchers also looked to see if the strains exhibiting similar growth curves also had similar genetic profiles. As it turns out, the two are completely uncorrelated, demonstrating once again how difficult it can be to map cellular traits and behaviors to specific stretches of DNA.

Moving forward, You plans to optimize the growth curve procedure to reduce the time it takes to identify a strain from 2 to 3 days to perhaps 12 hours. He's also planning on using high-definition cameras to see if mapping how bacterial colonies grow in space in a Petri dish can help make the process even more accurate.

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This research was conducted in collaboration with groups of Deverick J. Anderson, Joshua T. Thaden and Vance G. Fowler from the Duke University School of Medicine, and Minfeng Xiao from BGI Genomics.

This research was partially supported by the National Institutes of Health (LY, R01GM098642, R01GM110494, 1A1125604), the Army Research Office (LY, W911NF-14-1-0490), the David and Lucile Packard Foundation, the Shenzhen Peacock Team Plan grant (MX, No. KQTD2015033117210153), the Centers for Disease Control and Prevention (DJA, U54CK000164), AHRQ (DJA, R01-HS23821), NIH (VGF, R01-AI068804), and the National Science Foundation's Graduate Research Fellowship (CZ, HRM).

"Temporal encoding of bacterial identity and traits in growth dynamics." Carolyn Zhang, Wenchen Song, Helena R. Ma, Xiao Peng, Deverick J. Anderson, Vance G. Fowler Jr, Joshua T. Thaden, Minfeng Xiao, and Lingchong You. PNAS, 2020. DOI: 10.1073/pnas.2008807117

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"Grown-ups don't always get it right, you know"

New research shows children don't expect adults to have all the answers, and want them to understand more about the role of media messages and approval in their lives.

UNIVERSITY OF PORTSMOUTH

 

New research shows children don't expect adults to have all the answers, and want them to understand more about the role of media messages and approval in their lives.

When 11 year old Oscar told his mum, Dr Emma Maynard that "grown-ups don't always get it right, you know" the statement struck a chord with the Senior Lecturer in Education at the University of Portsmouth.

Dr Maynard and colleagues Sarah Barton and Kayleigh Rivett asked Oscar and some friends to create a series of interview questions they could ask each other, about their views on adult knowledge and decision making - the first time this is thought to have been done for a peer reviewed research paper. Although there have been many projects where children have actively participated in research, the authors are not aware of other studies where children have taken the lead from the original idea, through to peer-reviewed publication.

The results have just appeared in the Journal of Qualitative Research in Psychology (July 2020), with the children listed as co-authors of the report. It finds that children think adults spend their time worrying that they should know the answers to everything, but the young people who took part in the research don't believe they should feel like this.

The young researchers also reported feeling a huge importance in adults recognising their achievements. The group as a whole was very frustrated by knowing a right answer, but not being able to show it. They cited occasions when teachers picked other students to answer a question, and didn't give them a chance to show they had a correct response. They related this to the constant messages they receive from media and school about striving for perfection in their self image, bodies, and learning expectations. Adult acknowledgement seems to reassure children they are on the right track to meet the very high expectations surrounding them.

The entire group argued that adults complain too much about the new generation's attitude to digital devices and their online activity. They urge adults to listen more to them about what it is like to have been immersed in new technology since birth, rather than impose parental views based on a childhood without it. Dr Maynard analysed these responses, and a feeling from the group that, despite a desire to do so, they felt unable to stop constantly using their phones because they would "feel left out".

Dr Maynard said: "The children presented the concept of phones and social media as being 'just there', so now they have to use them. We interpreted this as the adult generation having created the assessment pressures, and the presence of social media and mobile phone based communication. Children did not invent these things. This led us to think that in this context, criticisms of children and young people being attached to their phones is somewhat unfair."

The paper shows that children don't always think that adult knowledge is superior, demonstrated in these quotes from the interview process:

Ben: "adults... just need to realise they might have forgotten"

Jamie: "adults can't think they're just the best because they've already been through their childhood..."

Harry: "just because they're older and they've already been to school, it doesn't mean they've paid attention in school"

Eve: "...because they say that... they were once a child too but because we're different I think we should be allowed to have our own opinions sometimes"

The report is seen as an excellent and a useful example of 'allyship' - a process of building relationships based on trust, consistency, and accountability. Dr Maynard is now recommending the approach to others in her field, noting that it has delivered rich and insightful findings from children who conclude: "If this childhood is different to yours, then listen to ours".

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WALDEN EFFECT

In a warming world, New England's trees are storing more carbon

Unprecedented 25-year study traced forest carbon through air, trees, soil, and water

HARVARD UNIVERSITY

 

IMAGE: AN EDDY-FLUX TOWER MEASURES ATMOSPHERIC CARBON DIOXIDE ENTERING AND LEAVING A DECLINING HEMLOCK STAND AT HARVARD FOREST. view more 

CREDIT: PHOTO BY DAVID FOSTER

Climate change has increased the productivity of forests, according to a new study that synthesizes hundreds of thousands of carbon observations collected over the last quarter century at the Harvard Forest Long-Term Ecological Research site, one of the most intensively studied forests in the world.

The study, published today in Ecological Monographs, reveals that the rate at which carbon is captured from the atmosphere at Harvard Forest nearly doubled between 1992 and 2015. The scientists attribute much of the increase in storage capacity to the growth of 100-year-old oak trees, still vigorously rebounding from colonial-era land clearing, intensive timber harvest, and the 1938 Hurricane - and bolstered more recently by increasing temperatures and a longer growing season due to climate change. Trees have also been growing faster due to regional increases in precipitation and atmospheric carbon dioxide, while decreases in atmospheric pollutants such as ozone, sulfur, and nitrogen have reduced forest stress.

"It is remarkable that changes in climate and atmospheric chemistry within our own lifetimes have accelerated the rate at which forest are capturing carbon dioxide from the atmosphere," says Adrien Finzi, Professor of Biology at Boston University and a co-lead author of the study.

The volume of data brought together for the analysis - by two dozen scientists from 11 institutions - is unprecedented, as is the consistency of the results. Carbon measurements taken in air, soil, water, and trees are notoriously difficult to reconcile, in part because of the different timescales on which the processes operate. But when viewed together, a nearly complete carbon budget - one of the holy grails of ecology - emerges, documenting the flow of carbon through the forest in a complex, multi-decadal circuit.

"Our data show that the growth of trees is the engine that drives carbon storage in this forest ecosystem," says Audrey Barker Plotkin, Senior Ecologist at Harvard Forest and a co-lead author of the study. "Soils contain a lot of the forest's carbon - about half of the total - but that storage hasn't changed much in the past quarter-century."

The trees show no signs of slowing their growth, even as they come into their second century of life. But the scientists note that what we see today may not be the forest's future. "It's entirely possible that other forest development processes like tree age may dampen or reverse the pattern we've observed," says Finzi.

The study revealed other seeds of vulnerability resulting from climate change and human activity, such as the spread of invasive insects.

At Harvard Forest, hemlock-dominated forests were accumulating carbon at similar rates to hardwood forests until the arrival of the hemlock woolly adelgid, an invasive insect, in the early 2000s. In 2014, as more trees began to die, the hemlock forest switched from a carbon "sink," which stores carbon, to a carbon "source," which releases more carbon dioxide to the atmosphere than it captures.

The research team also points to extreme storms, suburbanization, and the recent relaxation of federal air and water quality standards as pressures that could reverse the gains forests have made.

"Witnessing in real time the rapid decline of our beloved hemlock forest makes the threat of future losses very real," says Barker Plotkin. "It's important to recognize the vital service forests are providing now, and to safeguard those into the future."

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