Fishing out the bad apples: Novel quantitative method to assess the safety of food

Scientists from Korea develop an effective yet simple strategy to quantify histamine levels in fish samples

CHUNG ANG UNIVERSITY

Research News

 

IMAGE: SPOILED FOOD, ESPECIALLY FISH, CAN HAVE HIGH LEVELS OF HISTAMINE, WHICH CAN BE DANGEROUS TO HUMANS; THUS, IT IS IMPORTANT TO DEVISE METHODS FOR THE DETECTION OF SUCH HARMFUL CHEMICALS... view more 

CREDIT: UNSPLASH

Consumers of purchased foods have no way of ascertaining the quality and safety of the food that existing distribution systems deliver to their plates. Unfortunately, inappropriate refrigeration can sometimes lead to food spoilage, which is often difficult to detect. Such is the case for mackerel fish, which readily develop harmful levels of a substance called histamine when left at room temperature for too long. Histamine is neurotoxic and can trigger severe allergic reactions, including rashes, vomiting, and diarrhea. Because spoiled fish can sometimes look and smell completely normal, it is important to accurately quantify histamine levels in fish samples to ensure food quality has been properly maintained during transportation and storage.

Although several techniques to detect histamine exist, they generally require expensive and bulky equipment, as well as the presence of a qualified analyst. To address these limitations, a team of scientists at Chung-Ang University, Korea, recently developed a new quantification method that is simultaneously simple, effective, and inexpensive. In their study, which was led by Professor Tae Jung Park and Jong Pil Park and published in Biosensors and Bioelectronics, the team describes their novel approach based on the use of fluorescent carbon nanoparticles and a protein that binds strongly to histamine.

First, the scientists looked for peptides--short chains of amino acids--with the highest affinity and selectivity against histamine. To do this, they employed phage-display technology, in which the external proteins of genetically modified viruses are used to check for chemical interactions. After screening with a large peptide library, they identified the best one for their purposes, called "Hisp3."

Then, the scientists produced fluorescent carbon nanoparticles called "carbon quantum dots (CQDs)" and coated them with N-Acetyl-L-Cysteine (NAC), a naturally occurring compound that also binds to Hisp3. The CQDs are fluorescent, meaning that upon irradiation with ultraviolet light, they re-emit the captured energy at a lower, visible frequency. However, their fluorescence is "quenched" when Hisp3 is added to the mix, which binds to the NAC and covers the CQDs' surface.

This last part is essential to the method because, when a histamine-containing sample is mixed with the CQDs, the Hisp3 unbinds from the NAC and binds to the histamine, restoring the original fluorescence levels of the CQDs in direct proportion to the concentration of histamine (as shown in the accompanying figure). By comparing the initial and final fluorescence levels of the CQDs using a fluorescence detection instrument or a handheld UV-irradiation flashlight, it is possible to indirectly quantify the concentration or intensity of histamine in the sample.

The proposed strategy was validated using fish samples with known histamine concentrations and other established techniques as well. Surprisingly, the new method proved to be more powerful than existing ones despite being simpler, as Prof. Park remarks, "We managed to accurately measure histamine concentrations ranging from 0.1 to 100 parts per million, with a limit of detection as low as 13 parts per billion. This means our approach is not only more convenient but also more effective and sensitive than those currently available methods."

Thus, this new method can not only detect dangerous histamine levels, but can also assess the state and quality of food products, as Prof. Park explains, "While the detection of histamine as a harmful factor is important, our approach can further serve to objectively measure the quality and freshness of food, thereby contributing to increasing food safety and benefitting consumers."

Additionally, the proposed methodology could be applied using other peptides to accurately determine the concentration of different chemicals in food samples and biomedical specimens. If adopted by the food and medical diagnostic industries, this method could provide us with the much-needed assurance that the food we consume and the environmental conditions we live in are safe.

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Reference

Authors: Rongjia Shi (a), Shuaihui Feng (a), Chan Yeong Park (a), Kyung Yeol Park (a), Jeonghun Song (b), Jong Pil Park (b), Hyang Sook Chun (b), Tae Jung Park (a)

Title of original paper: Fluorescence detection of histamine based on specific binding bioreceptors and carbon quantum dots

Journal: Biosensors and Bioelectronics

DOI: 10.1016/j.bios.2020.112519

Affiliations:

(a) Department of Chemistry, Research Institute of Chem-Bio Diagnostic Technology, Chung-Ang University
(b) Department of Food Science and Biotechnology, School of Food Science and Technology, Chung-Ang University

About Chung-Ang University

Chung-Ang University is a private comprehensive research university located in Seoul, South Korea. It was started as a kindergarten in 1918 and attained university status in 1953. It is fully accredited by the Ministry of Education of Korea. Chung-Ang University conducts research activities under the slogan of "Justice and Truth." Its new vision for completing 100 years is "The Global Creative Leader." Chung-Ang University offers undergraduate, postgraduate, and doctoral programs, which encompass a law school, management program, and medical school; it has 16 undergraduate and graduate schools each. Chung-Ang University's culture and arts programs are considered the best in Korea.

Website: https://neweng.cau.ac.kr/index.do

About Professor Tae Jung Park from Chung-Ang University

Dr. Tae Jung Park is a Distinguished Professor in the Chemistry Department of Chung-Ang University, and his research interests include exploring novel technologies for bio-nano convergence studies, such as biosensors and nanocomplex fabrication. He received bachelor's and master's degrees from the Chungnam National University, Korea, in 1998 and 2000, respectively. He received his doctoral degree from the Department of Chemical & Biomolecular Engineering of KAIST in 2004. He previously served as a research professor and chief researcher at the BioProcess Engineering Research Center in KAIST. He has more than 215 publications to his credit.

Website: http://nbc.cau.ac.kr/

Crystal structures in super slow motion

Physicists from Göttingen first to succeed in filming a phase transition with extremely high spatial and temporal resolution

UNIVERSITY OF GÖTTINGEN

Research News

 

IMAGE: AT THE HEART OF THE IMAGING TECHNIQUE IS A COMPLEX ARRAY OF 72 CIRCULAR APERTURES view more 

CREDIT: DR MURAT SIVIS

Laser beams can be used to change the properties of materials in an extremely precise way. This principle is already widely used in technologies such as rewritable DVDs. However, the underlying processes generally take place at such unimaginably fast speeds and at such a small scale that they have so far eluded direct observation. Researchers at the University of Göttingen and the Max Planck Institute (MPI) for Biophysical Chemistry in Göttingen have now managed to film, for the first time, the laser transformation of a crystal structure with nanometre resolution and in slow motion in an electron microscope. The results have been published in the journal Science.

The team, which includes Thomas Danz and Professor Claus Ropers, took advantage of an unusual property of a material made up of atomically thin layers of sulphur and tantalum atoms. At room temperature, its crystal structure is distorted into tiny wavelike structures - a "charge-density wave" is formed. At higher temperatures, a phase transition occurs in which the original microscopic waves suddenly disappear. The electrical conductivity also changes drastically, an interesting effect for nano-electronics.

In their experiments, the researchers induced this phase transition with short laser pulses and recorded a film of the charge-density wave reaction. "What we observe is the rapid formation and growth of tiny regions where the material was switched to the next phase," explains first author Thomas Danz from Göttingen University. "The Ultrafast Transmission Electron Microscope developed in Göttingen offers the highest time resolution for such imaging in the world today." The special feature of the experiment lies in a newly developed imaging technique, which is particularly sensitive to the specific changes observed in this phase transition. The Göttingen physicists use it to take images that are composed exclusively of electrons that have been scattered by the crystal's waviness.

CAPTION

Artist's impression of the charge density wave in the ultrafast transmission electron microscope.

Florian Sterl (Sterltech Optics)

Their cutting-edge approach allows the researchers to gain fundamental insights into light-induced structural changes. "We are already in a position to transfer our imaging technique to other crystal structures," says Professor Claus Ropers, leader of Nano-Optics and Ultrafast Dynamics at Göttingen University and Director at the MPI for Biophysical Chemistry. "In this way, we not only answer fundamental questions in solid-state physics, but also open up new perspectives for optically switchable materials in future, intelligent nano-electronics."

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Original publication: Thomas Danz et al., Ultrafast nanoimaging of the order parameter in a structural phase transition, Science 2021, doi:10.1126/science.abd2774

Russian chemists developed polymer cathodes 

for ultrafast batteries

SKOLKOVO INSTITUTE OF SCIENCE AND TECHNOLOGY (SKOLTECH)

NEWS RELEASE 19-JAN-2021

Scientists are searching for lithium technology alternatives in the face of the surging demand for lithium-ion batteries and limited lithium reserves. Russian researchers from Skoltech, D. Mendeleev University, and the Institute of Problems of Chemical Physics of RAS have synthesized and tested new polymer-based cathode materials for lithium dual-ion batteries. The tests showed that the new cathodes withstand up to 25,000 operating cycles and charge in a matter of seconds, thus outperforming lithium-ion batteries. The cathodes can also be used to produce less expensive potassium dual-ion batteries. The research was published in the journal Energy Technology.

The amount of electricity consumed worldwide grows by the year, and so does the demand for energy storage solutions since many devices often operate in autonomous mode. Lithium-ion batteries can generate enormous power while showing fairly high discharge and charge rates and storage capacity per unit mass, making them a popular storage device in electronics, electric transport, and global power grids. For instance, Australia is launching a series of large-scale lithium-ion battery storage projects to manage excess solar and wind energy.

If lithium-ion batteries continue to be produced in growing quantities, the world may sooner or later run out of lithium reserves. With Congo producing 60% of cobalt for lithium-ion batteries' cathodes, cobalt prices may skyrocket. The same goes for lithium, as lithium mining's water consumption poses a great challenge for the environment. Therefore, researchers are looking for new energy storage devices relying on more accessible materials while using the same operating principle as lithium-ion batteries.

The team used a promising post-lithium dual-ion technology based on the electrochemical processes involving the electrolyte's anions and cations to attain a manifold increase in lithium-ion batteries' charging rate. Another plus is that the cathode prototypes were made of polymeric aromatic amines synthesized from various organic compounds.

"Our previous research addressed polymer cathodes for ultra-fast high-capacity batteries that can be charged and discharged in a few seconds, but we wanted more," says Filipp A. Obrezkov, a Skoltech Ph.D. student and the first author of the paper. "We used various alternatives, including linear polymers, in which each monomeric unit bonds with two neighbors only. In this study, we went on to study new branched polymers where each unit bonds with at least three other units. Together they form large mesh structures that ensure faster kinetics of the electrode processes. Electrodes made of these materials display even higher charge and discharge rates."

A standard lithium-ion cell is filled with lithium-containing electrolyte and divided into the anode and the cathode by a separator. In a charged battery, the majority of lithium atoms are incorporated in the anode's crystal structure. As the battery discharges, lithium atoms move from the anode to the cathode through the separator. The Russian team studied the dual-ion batteries in which the electrochemical processes involved the electrolyte's cations (i.e., lithium cations) and anions that get in and out of the anode and cathode material's structures, respectively.

Another novel feature is that, in some experiments, the scientists used potassium electrolytes instead of expensive lithium ones to obtain potassium dual-ion batteries.

The team synthesized two novel copolymers of dihydrophenazine with diphenylamine (PDPAPZ) and phenothiazine (PPTZPZ), which they used to produce cathodes. As anodes, they used metallic lithium and potassium. Since the cathode drives the key features of these battery prototypes called half-cells, the scientists assemble them to assess the capabilities of new cathode materials quickly.

While PPTZPZ half-cells showed average performance, PDPAPZ turned out to be more efficient: lithium half-cells with PDPAPZ were fairly quick to charge and discharge while displaying good stability and retaining up to a third of their capacity even after 25,000 operating cycles. If a regular phone battery were as stable, it could be charged and discharged daily for 70 years. PDPAPZ potassium half-cells exhibited a high energy density of 398 Wh/kg. For comparison, the value for common lithium cells is 200-250 Wh/kg, the anode and electrolyte weights included. Thus the Russian team demonstrated that polymer cathode materials could create efficient lithium and potassium dual-ion batteries.

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Skoltech is a private international university located in Russia. Established in 2011 in collaboration with the Massachusetts Institute of Technology (MIT), Skoltech is cultivating a new generation of leaders in the fields of science, technology, and business is researching in breakthrough fields, and is promoting technological innovation intending to solve critical problems that face Russia and the world. Skoltech is focusing on six priority areas: data science and artificial intelligence, life sciences, advanced materials and modern design methods, energy efficiency, photonics, and quantum technologies, and advanced research.
Web: https://www.skoltech.ru/.

The D. Mendeleev University of Chemical Technology of Russia, a mainstay university for the Russian chemical industry, aims to generate and integrate new knowledge in the industry. This study was performed by the researchers of the Skolkovo Institute of Science and Technology (Skoltech) and the Institute of Problems of Chemical Physics of RAS, as well as the students of D. Mendeleev University's Institute of Chemistry and Problems of Sustainable Development, with financial support from the Ministry of Science and Higher Education of Russia and the Russian Foundation for Basic Research (RFBR).

POSTMODERN ALCHEMY

Experimental evidence of an intermediate state of matter between a crystal and a liquid

MOSCOW INSTITUTE OF PHYSICS AND TECHNOLOGY

Research News

 

IMAGE: INTERMEDIATE PHASE. ILLUSTRATION. view more 

CREDIT: SCIENTIFIC REPORTS

Scientists from the Joint Institute for High Temperatures Russian Academy of Sciences (JIHT RAS) and Moscow Institute of Physics and Technology (MIPT) have experimentally confirmed the presence of an intermediate phase between the crystalline and liquid states in a monolayer dusty plasma system. The theoretical prediction of the intermediate - hexatic - phase was honoured with the Nobel Prize in Physics in 2016: the prize was awarded to Michael Kosterlitz, David Thouless and Duncan Haldane with the formulation "for theoretical discoveries of topological phase transitions and topological phases of matter."

In a scientific article in the journal Scientific Reports, the JIHT RAS scientists published their observations and detailed descriptions of experiments, during which they first observed the hexatic phase in two-dimensional structures in plasma. The paper describes methods for accurately identifying phase transition points and presents a detailed analysis of the structural properties of such a system. The data obtained during the experiment are fully consistent with the Berezinsky-Kosterlitz-Thouless theory.

"Our design of experiment makes it possible to clearly observe a two-stage process of crystal melting and to identify the points of the phase transition "solid-hexatic phase " and "hexatic phase-liquid," said Ph.D. Elena Vasilieva, the senior researcher in Laboratory of Dusty Plasma Diagnostics, JIHT RAS. "The long time of the experiment, sufficient to establish a stationary state of the system, in combination with precise methods of controlling the temperature of particles, made it possible to smoothly change the parameters of the system and "catch" the hexatic phase."

According to Elena Vasilieva, despite the existence of the Berezinsky-Kosterlitz-Thouless theory for more than 40 years, which predicts two-stage melting from a crystal to a liquid phase with the formation of an intermediate hexatic phase, it has not yet been possible to study these processes in laboratory plasma systems. Two-dimensional transitions have already been observed in polymer colloids, magnetic bubbles in thin films, liquid crystals, and superconductors, but there has been no experimental evidence of two-stage melting in dusty plasmas for a long time.

"Our experiment was successful due to a number of factors. For example, we used an unconventional approach to form a monolayer dusty system, namely we used particles with a metal surface that are capable of absorbing laser radiation and converting it into the energy of their own motion. The particle system had a long time for relaxation before recording the experimental series. In addition, a homogeneous laser beam was used to uniformly influence the structure and its precise heating," commented Oleg Petrov, the director of the Joint Institute for High Temperatures Russian Academy of Sciences.

The study of the physical properties of two-dimensional systems is of great practical importance. Such research is now rapidly developing, promising in the future new materials with desired properties and devices based on them in microelectronics, medicine for DNA sequencing, etc.

The results presented in the article were obtained with the support of the Russian Science Foundation in the framework of the project "Active Brownian motion of Coulomb particles in plasma and superfluid helium."

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Genetic rewiring behind spectacular evolutionary explosion in East Africa

EARLHAM INSTITUTE

Research News

 

IMAGE: SAMPLING CICHLID FISH TISSUES FOR GENOME AND TRANSCRIPTOME SEQUENCING IN TANZANIA AND ZANZIBAR ARCHIPELAGO. TILAPIA AND HAPLOCHROMINE CICHLID FISH SPECIES WERE SAMPLED FOR ASSOCIATED STUDIES ON CHARACTERISING GENOMIC SIGNATURES OF... view more 

CREDIT: DR GRAHAM ETHERINGTON AND DR TARANG MEHTA, EARLHAM INSTITUE (EI)

Genetic rewiring could have driven an evolutionary explosion in the shapes, sizes and adaptations of cichlid fish, in East Africa's answer to Darwin's Galapagos finches.

Published in BMC Genome Biology, an Earlham Institute (EI) study, with collaborators at the University of East Anglia (UEA) and Wisconsin Institute for Discovery, shows that 'genetic rewiring' at non-coding regions - rather than mutations to protein-coding regions of genes - may play an important role in how cichlid fish are able to rapidly adapt to fill a staggeringly wide range of environmental niches in the East African Rift lakes.

The results could help future studies to improve breeding of economically important cichlid species such as tilapia - a staple in aquaculture.

Darwin's famous finches are one of the most well-known examples of evolution by natural selection, and specifically adaptive radiation. The birds he observed on the Galapagos archipelago had differences in their beaks that could be matched to fit their specific feeding habits - whether they ate big or small seeds, insects, or even used tools to find food.

Amazingly, in the 2-3 million years it took 14 species of finch to evolve on the Galapagos Islands, around 1,000 species of cichlid evolved in Lake Malawi alone.

"In the Great Lakes of East Africa, and within the last few million years, a few ancestral lineages of cichlid fish have independently radiated and given rise to well over 2,000 species - and we're still finding new ones," says first author Dr Tarang Mehta, a postdoctoral scientist in EI's Haerty Group.

"They occupy a really large diversity of freshwater ecological niches in lakes, rivers and even swamps: this includes sandy substrates, mud, rocks, and vegetated bottoms. As a result, they are all adapted to different dietary habits and niches in these areas."

By looking at gene expression across different cichlid tissues in five representative species from East African rivers and the Great Rift Lakes, the team discovered an evolutionary rewiring of several important genes linked to the adaptability seen in cichlids. The effect which was particularly prominent in the vision of fish species.

"We found out that the most rewired genes are associated with the visual system," explains Dr Mehta. "Essentially, if you look at the different species of fish we used in the study, you could see major differences in the regulation network around opsin genes they use for vision depending on where they live and what they eat.

"For example, the Lake Malawi rock-dwelling species, M. zebra, feeds on UV-absorbing phytoplankton algae. That generally requires increased expression of a particular opsin, SWS1, which helps with sensitivity to UV light. That may well explain why it has a more complex regulatory network around SWS1 compared with the Lake Tanganyika benthivore, N. brichardi, which does not share the same diet or habitat."

Armed with some genes of interest, the team confirmed the mechanisms behind these gene regulatory differences in the lab. Looking at the fine scale, they identified small changes in the DNA sequence of regulatory regions at the start of genes important for trait differences between species, including the visual system.

Rather than the gene itself being modified, it was the regions of DNA known as binding sites that are targeted by transcription factors - the proteins which determine whether a gene is turned on or turned off. In this way, the different species of fish can be said to have had their visual system 'rewired' for different functions.

Taking this further, the team was able to show that these changes could be commonly associated throughout cichlid fish in Lake Malawi, with diet and ecology-dependent rewiring showing that changes in transcription factor binding could be key to fine-tuning visual sensitivity.

Depending on the trait, cichlids appear to utilise an array of genetic mechanisms to generate phenotypic novelty however, the 'tinkering' of regulatory systems appears more widespread in cichlid fish than previously discovered. This evolutionary plasticity could well explain the explosion of species in such a small area over a relatively short time.

"It's a proof of concept," says Dr Mehta. "As more data comes out, we'll be able to look at this in depth in representative clades from each of the different radiations, not just in Lake Malawi but also Lake Tanganyika, Lake Victoria and even in some of the cichlids in South America."

Professor Federica Di Palma, Professorial Fellow of Biodiversity at UEA, said: "We have released an impressive amount of expression data which will further aid studies into the adaptive radiation of cichlids for the future. We are now deciphering the complexity of these cis-regulatory regions by using genome-wide CRISPR screens.

"The wider impact of our regulatory gene network approach will also help inform evolution of agriculturally important traits for tilapia such as growth rate and tolerance to different local water conditions, as well as for general aquaculture and fisheries."

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You can access the paper, here: https://genomebiology.biomedcentral.com/articles/10.1186/s13059-020-02208-8

Scientists present novel approach for monitoring freshwater health

Study describes how the world's smallest portable DNA sequencing device helps simplify the monitoring of bacteria in freshwater ecosystems

ELIFE

Research News

 

IMAGE: THE MINION IS A PORTABLE DEVICE THAT CAN SEQUENCE GENETIC MATERIAL SAMPLED FROM THE ENVIRONMENT - HERE, FROM THE RIVER CAM IN CAMBRIDGE, UK. view more 

CREDIT: TEAM PUNTSEQ (CC BY 4.0)

Researchers have used the world's smallest, smartphone-sized DNA sequencing device to monitor hundreds of different bacteria in a river ecosystem.

Writing in the journal eLife, the interdisciplinary team from the University of Cambridge, UK, provide practical and analytical guidelines for using the device, called the MinION (from Oxford Nanopore Technologies), to monitor freshwater health. Their guidelines promise a significantly more cost-effective and simple approach to this work outside the lab, compared to existing methods.

Rowers and swimmers in Cambridge are regularly affected by waterborne infections such as Weil's disease, sometimes leading to public closures of the city's iconic waterways. Monitoring the microbial species in freshwater can help indicate the presence of disease-causing microorganisms and even water pollution. But traditional tests for freshwater bacteria often require well-equipped laboratories and complex methods for growing colonies of individual bacterial species.

"The direct measurement of all bacterial DNA traces in freshwater, an approach known as metagenomics, is a valuable alternative, but still requires large, expensive equipment that can be hard to operate," says Andre Holzer, co-first author and PhD student at the Department of Plant Sciences, University of Cambridge. "We aimed to describe the bacterial species present in the River Cam using the new portable DNA sequencing technology."

The team used the MinION device to sequence the DNA of entire groups of microorganisms found in water samples from the River Cam. But before they could use the sequence data, they needed to optimise their experimental methods and analysis software. "It was essential to account for the quality of this new type of bacterial DNA sequence information," Holzer explains. "We tested many different algorithms for processing the data to find the most accurate methods."

The researchers then used their optimised guidelines to analyse the data and successfully measure the proportions of hundreds of different bacterial species present in the water. They took samples from nine different sites along the river, often sampling the sites at three different time points so they could compare the proportions of species in different locations and seasons.

The team was also able to distinguish closely related, harmful microbial species from non-harmful ones. By comparing the samples from different locations, they found that there were more potentially harmful bacteria and those associated with wastewater downstream of the most built-up, urban areas of the river. Chemical follow-up analyses of the water samples collected from the same urban areas revealed a matching trend of increasing wastewater pollution in those areas.

"Our work shows how MinION and the associated DNA sequencing technology can be used in the effective monitoring of freshwater health," says Lara Urban, co-lead investigator of the work and now an Alexander von Humboldt Research Fellow at the University of Otago, New Zealand. "This expands on the technology's existing applications which include the accurate tracing of viral transmissions between patients during the recent Ebola, Zika and SARS-CoV-19 virus outbreaks."

"We hope our results will encourage other independent scientists and collectives to engage in simplified freshwater management and biodiversity tests around the globe,"concludes senior author Maximilian Stammnitz, a PhD student at the Department of Veterinary Medicine, University of Cambridge.

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References

The paper 'Freshwater monitoring by nanopore sequencing' can be freely accessed online at https://doi.org/10.7554/eLife.61504. Contents, including text, figures and data, are free to reuse under a CC BY 4.0 license.

This study was supported by grants from the OpenPlant Fund (BBSRC), University of Cambridge RCUK Catalyst Seed Fund (Public Engagement Starter Grant), Natural Environment Research Council and Gates Cambridge Trust.

To find out more about the Punting & Sequencing (PuntSeq) project and the team behind it, visit http://www.puntseq.co.uk.

Media contact

Emily Packer, Media Relations Manager
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 and Microbiology and Infectious Disease, 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.

And for the latest in Microbiology and Infectious Disease, see https://elifesciences.org/subjects/microbiology-infectious-disease.

A sea of rubbish: ocean floor landfills

The long journey of litter to seafloor

The Messina Strait, a submarine bridge separating the island of Sicily from the Italian Peninsula, is the area with the largest marine litter density worldwide -more than a million objects per square kilometre in some parts-, as reported in a new review paper published in the journal Environmental Research Letters.

Also, over the next thirty years, the volume of rubbish in the sea could surpass three billion metric tons (Mt), as cited in the study, whose corresponding authors are the experts Miquel Canals, from the Faculty of Earth Sciences of the University of Barcelona, and Georg Hanke from the European Commission's Joint Research Centre (JRC), where scientists carry out research in order to provide independent scientific advice and support to EU policies.

Led by the University of Barcelona, this paper gathers the results of the scientific meeting on macrolitter that took place in May 2018, promoted by the European Commission's Joint Research Centre (JRC) and the German Alfred Wegener Institute (AWI). A team of twenty-five scientists from across the world treated issues such as data needs, methodologies, harmonisation and needs for further development.

The study provides a synthesis of current knowledge on human-sourced materials lying on the seafloor and goes through the methodologies to improve future studies, "highlighting the need to understand litter occurrence, distribution and quantities in order to provide insight for appropriate (policy) measures", notes Georg Hanke, who adds that "the paper also shows the need to employ new methodologies -i.e. imaging approaches- to cover areas that had not been considered previously, and provides tools to enable quantitative assessments such as those under the EU Marine Strategy Framework Directive (MSFD)".

Among other signatories of the article are experts from the University of Açores (Portugal), Alfred Wegener Institute (Germany), Utrecht University (Netherlands), the Norwegian Institute of Marine Research (Norway), the Secretariat of the Barcelona Convention on the protection of the Mediterranean Sea, Monterey Bay Aquarium Research Institute (MBARI, California, United States), the Institute for Global Change of the Japan Agency for Marine Earth Science and Technology Research (JAMSTEC, Japan), IFREMER (France) and Oxford University (United Kingdom), among other institutions.

When litter arrives before humans do

The ocean floor is increasingly accumulating marine litter. Whereas the largest seafloor litter hotspots -likely in the deep sea- are still to be found, plastics have already been found in the deepest point on Earth, the Mariana Trench -at a depth of 10,900 meters- in the Pacific Ocean. In some cases, litter concentrations reach densities comparable to large landfills, experts warn.

Despite the scientific community efforts, "the extent of marine litter on our seas and oceans is not yet fully known. The marine regions most affected by this problem are in landlocked and semi-enclosed seas, coastal bottoms, marine areas under the influence of large river mouths, and places with high fishing activity, even far from land", says Professor Miquel Canals, head of the Consolidated Research Group on Marine Geosciences at UB.

Canals highlights that "the level of waste treatment in coastal countries is decisive: the less treatment -or the more deficient-, the more waste reaching the ocean, and therefore, the ocean floor, which is a problem that affects specially third world countries".

The long journey of litter to seafloor

Plastics, fishing gears, metal, glass, ceramics, textiles and paper are the most abundant materials in seafloor litter hotspots. Geomorphological features, the submarine relief and the nature of the seafloor determine the distribution of litter items on the seabed. Ocean dynamics, --that is, processes such as dense water cascades, ocean currents and storms-- ease the transport and dispersal of litter across the ocean, from coasts to abyssal plains, thousands of meters deep. However, these factors do not occur in all ocean ecosystems and also vary over time and in intensity where they take place.

Due to a gravitational effect, light waste is usually transported along and into marine regions where dense currents flow --i.e. submarine canyons and other submarine valleys-- and where flow lines concentrate, such as nearby large submarine reliefs. Finally, materials transported by ocean dynamics accumulate in depressions and quiet marine areas.

The properties of materials dumped in the marine environment also affect their dispersion and accumulation on the ocean floor. It is estimated that 62% of the dirt accumulated on seabeds is made of plastics, "which is relatively light and easy to transport over long distances. On the other hand, heavy objects such as barrels, cables or nets are usually left at the point where they are initially fell or got entangled", says Canals.

Litter drowns marine life

Litter is a new threat to marine biodiversity. It is already known that nearly 700 marine species, 17% of which are on the IUCN red list, have been affected by this problem in several ways. Seabed entangled fishing gears can cause serious ecological impacts for decades because of ghost fishing. The slow decomposition of fishing nets -usually made of high-strength polymers- aggravates the detrimental effects of this type of waste on the marine ecosystem.

Other human activities -dredging, trawling, etc.- trigger secondary dispersal by remobilization and fragmentation of seafloor litter. In addition, seabed waste concentrations can easily trap other objects, thus generating larger and larger litter accumulations. It is paradoxical that waste may increase the heterogeneity of the substrate, which can benefit some organisms. Some xenobiotic compounds -pesticides, herbicides, pharmaceuticals, heavy metals, radioactive substances, etc.- associated to litter are highly resistant to degradation and endanger marine life. However, the extent of the effects of litter on the habitats of the vast expanses of the deep ocean still is a chapter to be written by the scientific community.

"In the Mediterranean Sea -says Miquel Canals- seafloor marine litter already is a serious ecological problem. In some places of the Catalan coast, there are large accumulations of waste. When there are strong storms, such as Gloria, in January 2020, waves throw this waste on the beach. Some beaches in the country were literally paved with rubbish, thus showing to which extent the coastal seabed is littered. There are also noticeable concentrations of waste in some submarine canyons outside Catalonia".

Robotic technology for large depths

Beach litter and floating garbage can be identified and monitored by simple, low-cost methods. In contrast, the study of seafloor litter is a technological challenge, the complexity of which increases with water depth and remoteness of the marine area to be investigated. The study reviews both methodologies allowing physical sampling of seafloor waste and in situ observations.

New technologies have enabled major advances in the study of the environmental status of the seabed worldwide. The use of unmanned remotely operated vehicles (ROVs) is critical for in situ observation, despite the limitations for physical sampling. Classic technologies such as bottom trawling also have limitations, as they do not allow determining the precise location of the bottom-sampled objects. "Future methodologies should aim at easing the comparison of scientific data from different places. It should also be easier for observation and sampling efforts to generate consistent data sets, something that we are still far from achieving", says Canals.

Avoiding excess waste generation to take care of the planet

Knowledge and data about seafloor litter are necessary for the implementation of the Marine Strategy Framework Directive (MSFD) and other international policy frameworks, including global agreements. The publication shows how research on seafloor macrolitter can inform these international protection and conservation frameworks to prioritize efforts and measures against marine litter and its deleterious impacts.

The authors warn about the need to promote specific policies to minimize such a serious environmental problem. The study also addresses the debate on the removal of litter from the seabed, a management option that should be safe and efficient. In relation to this, the Joint Research Centre (JRC) is co-chairing the MSFD Technical Group on Marine Litter, which provides an information exchange and discussion platform to provide agreed guidance for MSFD implementation.

"Marine litter has reached the most remote places in the ocean, even the least (or never) frequented by our species and not yet mapped by science," says Miquel Canals. "In order to correct something bad, we must attack its cause. And the cause of the accumulation of waste on the coasts, seas and oceans, and all over the planet, is the excess waste generation and spillage in the environment, and poor or insufficient management practices. As humans, we have little or no care at all to prevent litter from accumulating everywhere".

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JAMSTEC's Deep-sea Debris Database [video] |

 EurekAlert! Science News

Improving long-term climate calculations

A new method reduces uncertainties in computer model estimations of climate change over thousands of years.

UNIVERSITY OF COPENHAGEN - FACULTY OF SCIENCE

Research News 

IMAGE: THE APPROACH OF BASTIANSEN ET AL. RESULTS IN MORE ACCURATE ESTIMATIONS OF LONG-TERM WARMING. view more 

CREDIT: TIPES/HP

Climate researchers have found a simple but efficient way to improve estimations of ultimate global warming from complex climate models. The finding is relevant for the evaluation and comparison of climate models and thus for accurate projections of future climate change - especially beyond the year 2100. The study is published in Geophysical Research Letters by Dr. Robbin Bastiaansen and colleagues at the Institute for Marine and Atmospheric Research Utrecht, Utrecht University, The Netherlands. The work is part of the European TiPES project coordinated by the University of Copenhagen, Denmark.

Complex climate models are rarely used to simulate the effect of global warming for a given amount of CO2 beyond a couple of centuries into the future. The reason for this is twofold. First, even on a supercomputer, such a model must already run for months to obtain a 150-year projection; reaching the end of a long simulation is therefore not practical. Second, policymakers are mainly concerned about how much climate change a given amount of CO2 will cause within the coming decades.

Earth warms for more than 1000 years

In the real world, however, temperatures continue to go up for more than a thousand years after CO2 is added to the Earth system. A typical climate model simulation therefore estimates less than half of the summed global warming. That is a challenge because, in order to improve models, it is necessary to compare and evaluate models. The final global mean temperature from a given amount of CO2 is an important parameter in the evaluation of a model.

The traditional way of solving this problem is to take the two most predominant results (called observables) from the simulation of the first 150 years and use these to estimate at which global mean surface temperature a full simulation would have ended. The two observables most often used are the global mean surface temperature and the radiation imbalance at the top of the atmosphere. This leads to a rather good estimation but the approach introduces considerable uncertainty - mainly underestimating total global warming.

More accurate estimates

However, an advanced climate model produces a multitude of other data on, for example future ocean currents, weather patterns, sea ice extend, ground color, climate belts, precipitation, and many more.

"And what we did, was add another observable on top of the two traditional ones. That is the idea. If you use additional observables, you will improve estimates over longer time scales. And our work is proof that this is possible," explains Dr. Robbin Bastiaansen.

In the best-case scenario, the new method halved the uncertainty compared to traditional methods.

The work is expected to be useful in assessing tipping points in the Earth system, as studied in the TiPES project, funded by the EU Horizon 2020.

CAPTION

Earth takes thousands of years to reach the final global mean temperature.

CREDIT

TiPES/HP

With a little help from their friends, older birds breed successfully

UNIVERSITY OF GRONINGEN

Research News

 

IMAGE: THIS IS A SEYCHELLES WITH A COLOUR-CODED RING. THESE RINGS MAKE IT POSSIBLE TO STUDY INDIVIDUAL ANIMALS ON THE ISLAND OF COUSIN. view more 

CREDIT: MARTIJN HAMMERS, UNIVERSITY OF GRONINGEN

The offspring of older animals often have a lower chance of survival because the parents are unable to take care of their young as well as they should. The Seychelles warbler is a cooperatively breeding bird species, meaning that parents often receive help from other birds when raising their offspring. A study led by biologists from the University of Groningen shows that the offspring of older females have better prospects when they are surrounded by helpers. This impact of social behaviour on reproductive success is described in a paper that was published on 19 January in the journal Evolution Letters.

The Seychelles warbler lives on a tiny island called Cousin Island, which is part of the Republic of Seychelles, an island country in the Indian Ocean. On Cousin Island, there are just over 300 birds, nearly all of them ringed with colour rings so that each individual bird can be recognized. The population has been studied for several decades. Martijn Hammers, a biologist at the University of Groningen, has frequently visited the island and is studying the interaction between social behaviour and ageing among these birds.

Natural laboratory

Cousin Island resembles a natural laboratory, Hammers explains. 'It is isolated, so there is no influx of new birds and birds rarely migrate to other islands. Furthermore, from 1985 onwards, we have ringed almost all warblers on the island, which allows us to observe their behaviour, reproduction and survival.' The Seychelles warbler is a cooperative breeder: each territory is held by a dominant couple and they sometimes allow helpers to stay there. 'These helpers are usually their own young from earlier breeding attempts and they can assist in breeding and in feeding the chicks. In return, these helpers can use the resources that are available in the territory and female helpers are occasionally allowed to lay an egg in the dominant birds' nest.'

As the parent birds age, their ability to feed their young diminishes. In this new study, Hammers and his colleagues from the University of Groningen (The Netherlands) and the University of East Anglia (UK) wanted to find out whether social behaviour, in particular the care for offspring provided by helpers, affects the breeding success of older birds. To this end, Hammers analysed over 20 years of data on these birds. He specifically looked at the frequency of chick feeding and the survival of young birds.

CAPTION

This picture shows two Seychelles warblers on the island of Cousin, feeding a young bird that has left the nest.

CREDIT

Charlie Davies

Humans

Our prediction was that having helpers would be beneficial for the survival of chicks from older birds. And this turned out to be true, but only for older females,' says Hammers. The males of this species contribute less to feeding the chicks than females and their behaviour may therefore be less important for offspring survival than the behaviour of the females. 'That may be because the males are not always sure that they are feeding their own offspring since 40 per cent of the young are not their own,' explains Hammers.

The data show that while helpers compensate for age-related declines in female reproductive performance, individual helpers do not work harder when the dominant female is older. 'It appears to be a more passive process, in that older birds recruit more helpers who collectively help more.' The implications of his findings are that it is beneficial for older female birds to display social behaviour - allowing helpers to live in their territory - since it increases their reproductive success. 'It would be interesting to see if this is a general principle that also applies to other animal species, or even to humans.'

In a previous study, Hammers showed that getting help with the kids also slows down the ageing of the parents. 'This effect was also most pronounced in older females. This new study provides additional evidence for an interplay between age and cooperative breeding.'

CAPTION

This picture shows University of Groningen biologist Martijn Hammers during fieldwork on Cousin. He holds a Seychelles warbler.

CREDIT

Charlie Davies

Reference: Martijn Hammers, Sjouke A. Kingma, Lotte A. van Boheemen, Alexandra M. Sparks, Terry Burke, Hannah L. Dugdale, David S. Richardson and Jan Komdeur: Helpers compensate for age-related declines in parental care and offspring survival in a cooperatively breeding bird. Evolution Letters 19 January 2021