It’s possible that I shall make an ass of myself. But in that case one can always get out of it with a little dialectic. I have, of course, so worded my proposition as to be right either way (K.Marx, Letter to F.Engels on the Indian Mutiny)
Saturday, October 26, 2024
Study of chick peeps could improve understanding of animal emotions
Acoustic study could improve animal welfare, anxiety medication production
Credit: Graphic by Jordan Thweatt/University of Mississippi Marketing and Communications
OXFORD, Miss. – Understanding animal emotions has been a long-running question at the forefront of welfare studies, but a University of Mississippi professor’s work may hold the key to decoding the chatter.
The answer involves two baby chickens and a mirror.
Kenneth Sufka, professor of psychology and pharmacology, partnered with a team of animal welfare researchers in the United Kingdom to study avian emotions through the common domestic chick’s peeps and whistles. Their research was recently published in Applied Behaviour Science.
Their findings could improve animal welfare across the poultry production industry. It could also improve testing for medications to treat depression and anxiety in people.
“Is there a noninvasive way that can capture in freely moving animals a measure of stress states?” he said. “That was the question we wanted to address in this chick study, looking at the calling or the vocalizations that are emitted, but in a way more sophisticated way than I have ever done.”
To conduct the study, the UK researchers expanded on previous results from Dr. Sufka’s lab. The experimental set up involved complex acoustic equipment in a secluded room. In one box, they placed a chick, and in another, they placed a chick with a mirror.
The chicken that can see its reflection believes it is not alone, and its calls represent a relatively calm chick, that isn’t too stressed. The chick that is alone, however, begins to voice loud, higher pitched sounds that the researchers believe could indicate an anxiety-like state. The acoustic data the researchers gathered measured how the quality of the chick’s vocalizations changed, and what that meant for their stress level.
Being able to detect stress could open the doorway to more humane, responsive practices in the meat and egg industry.
“In production facilities, in commercial growing facilities across the board – be it cattle, swine or avian models like chickens – there's a real concern about welfare,” he said. “Is this a worthwhile thing, to be thinking about using acoustics to monitor animal welfare in these production facilities? I think so.”
While researchers – and farmers – have long known that a loud chick is a distressed chick, the knowledge never went much deeper than that, said Sarah Collins, coauthor and associate professor of animal behavior at the University of Plymouth.
“This is more evidence of animal sentience – the ability to experience feelings,” she said. “We have known for a while that chick distress calls mean they are stressed, but knowing we can tell how stressed means we can assess welfare more precisely.”
The study also presents a noninvasive, comparatively inexpensive way to study anxiety-like states in animals. In previous models, the way to measure an animal’s stress levels included capturing it, withdrawing blood and measuring levels of corticosterone, a stress hormone.
“That itself is stressful – to capture, restrain, collect, release,” Sufka said. “This, we think, is a better way.”
Medications intended for humans often must go through chick, rat and primate studies before any testing on human subjects. But since chicks are often used as an early precursor to human studies, understanding their emotions could improve studies on anxiety and depression medication.
Like many humans, chicks are often resistant to many common depression medications, making them a prime subject for alternative treatments. But if researchers cannot prove that the chick first has anxiety-like symptoms, they cannot show that a medication improves that state.
“To claim that an anti-anxiety drug is alleviating an anxiety-like state, this chick or mouse or rat has to have an anxiety state similar to yours,” Sufka said. “The behavior (of an animal in an anxiety-like state) is totally different, but it's behavior in the context of what that animal does.
“If I make an argument that I've got a drug that reduces that state, that would necessitate in a validation argument that animals have to have emotional states.”
But the research also points toward an answer to an older, more complex question: What rights do animals have? The long-held answer is that animals do not have the same emotional capabilities as humans, and therefore have fewer needs and wants.
“My argument is that all of the work that we have done to-date shows the similarities between this avian model and human anxiety and depressive states makes a very strong argument that these animals do have negative emotional states,” Sufka said.
“And if that's true, then ethically it follows that we are absolutely obligated to be worried about animal welfare and provide for the best living conditions possible.”
Do I sound anxious? Emotional arousal is linked to changes in vocalisations in domestic chicks (Gallus gallus dom.)
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"Dying or Lying? For-Profit Hospices and End of Life Care"
Study: Hospice care provides major Medicare savings
The late-in-life health care option reduces patient costs, even as for-profit organizations expand in the sector.
Massachusetts Institute of Technology
Hospice care aims to provide a health care alternative for people nearing the end of life, by sparing them unwanted medical procedures and focusing on the patient’s comfort. A new study co-authored by MIT scholars shows hospice also has a clear fiscal benefit: It generates substantial savings for the U.S. Medicare system.
The study examines the growth of for-profit hospice providers, who receive reimbursements from Medicare, and evaluates the cost of caring for patients with Alzheimer’s Disease and related dementias (ADRD). The research finds that for patients using for-profit hospice providers, there is about a $29,000 savings to Medicare over the first five years after someone is diagnosed with ADRD.
“Hospice is saving Medicare a lot of money,” says Jonathan Gruber, an MIT health care economist and co-author of a paper detailing the study’s findings. “Those are big numbers.”
In recent decades, hospice care has grown substantially. That growth has been accompanied by concerns that for-profit hospice organizations, in particular, might be overly aggressive in pursuing patients. There have also been instances of fraud by organizations in the field. And yet, the study shows that the overall dynamics of hospice are the intended ones: People are indeed receiving palliative-type care, based around comfort rather than elaborate medical procedures, at less cost.
“What we found is that hospice basically operates as advertised,” adds Gruber, the Ford Professor of Economics at MIT. “It does not extend lives on aggregate, and it does save money.”
The paper, “Dying or Lying? For-Profit Hospices and End of Life Care,” has been accepted for publication in the American Economic Review. The co-authors are Gruber, who is also head of MIT’s Department of Economics; David Howard, a professor at the Rollins School of Public Health at Emory University; Jetson Leder-Luis PhD ’20, an assistant professor at Boston University; and Theodore Caputi, a doctoral student in MIT’s Department of Economics.
Charting what more hospice access means
Hospice care in the U.S. dates to at least the 1970s. Patients opt out of their existing medical network and receive nursing care where they live, either at home or in care facilities. That care is oriented around reducing suffering and pain, rather than attempting to eliminate underlying causes. Generally, hospice patients are expected to have six months or less to live. Most Medicare funding goes to private contractors supplying medical care, and in the 1980s, the federal government started using Medicare to reimburse the medical expenses from hospice as well.
While the number of nonprofit hospice providers in the U.S. has remained fairly consistent, the number of for-profit hospice organizations grew fivefold between 2000 and 2019. Medicare payments for hospice care are now about $20 billion annually, up from $2.5 billion in 1999. People diagnosed with ADRD now make up 38 percent of hospice patients.
Still, Gruber considers the topic of hospice care relatively under-covered by analysts. To conduct the study, the research team examined over 10 million patients from 1999 through 2019, and used the growth of for-profit hospice providers to compare the effects of being enrolled in non-profit hospice care, for-profit hospice care, or staying in the larger medical system.
That means the scholars were not only evaluating hospice patients; by evaluating the larger population in a given area where and when for-profit hospice firms opened their doors, they could see what difference greater access to hospice care made. For instance, having a new for-profit hospice open locally is associated with a roughly 2 percentage point increase in for-profit hospice admissions in following years.
“We’re able to use this methodology to [analyze] if these patients would otherwise have not gone to hospice, or would have gone to a nonprofit hospice,” Gruber says.
The method also allows the scholars to estimate the substantial cost savings. And it shows that enrolling in hospice increased the five-year post-diagnosis mortality rate of ADRD patients by 8.6 percentage points, from a baseline of 66.6 percent. Entering into hospice care — which is a reversible decision — means foregoing life-extending surgeries, for instance, if people believe such procedures are no longer desirable for them.
Rethinking the cap
By providing care without more expensive medical procedures, it is understandable that hospice reduces overall medical costs. Still, given that Medicare reimburses hospice organizations, one ongoing policy concern is that hospice providers might aggressively recruit a larger percentage of patients who end up living longer than six additional months. In this way hospice providers might unduly boost their revenues and put more pressure on the Medicare budget.
To counteract this, Medicare rules include a roughly $29,205 cap on per-patient reimbursements, as of 2019. Most patients die relatively soon after entering hospice care; some will outlive the six-month expectation significantly. But hospice organizations cannot exceed that average.
However, the study also suggests the cap is a suboptimal approach; in 2018, 15.5 percent of hospice patients were being discharged from hospice care while still alive, due to the cap limiting hospice capacity. As the paper notes, “patients in hospices facing cap pressure are more likely to be discharged from hospice alive and experience higher mortality rates.”
As Gruber notes, the spending cap is partly a fraud-fighting tool. And yet the cap clearly has other, unintended consequences on patients and their medical choices, crowding some out of the hospice system.
“The cap may be throwing the baby out with the bathwater.” Gruber says. “The government has more focused tools to fight fraud. Using the cap for that is a blunt instrument.”
As long as people are informed about hospice and the medical trajectory it puts them on, then, hospice care appears to be providing a valued service at less expense than other approaches to end-of-life care.
“The holy grail in health care is things that improve quality and save money,” Gruber says. “And with hospice, there are surveys saying people like it. And it certainly saves money, and there’s no evidence it’s doing harm [to patients]. We talk about how we struggle to deal with health care costs in this country, so this seems like what we want.”
The research was supported in part by the National Institute on Aging of the National Institutes of Health.
###
Written by Peter Dizikes, MIT News
Paper: “Dying or Lying? For-Profit Hospices and End of Life Care”
PLYMOUTH MEETING, PA [October 24, 2024] — New research published online-ahead-of-print in JNCCN—Journal of the National Comprehensive Cancer Networkfound that people with newly-diagnosed hormone receptor (HR)-negative, human epidermal growth factor receptor 2 (HER2)-positive breast cancer were more likely to receive timely, guideline-concordant treatment and have longer survival in states that participate in Medicaid expansion under the Affordable Care Act (ACA).
A team of researchers—led by the American Cancer Society (ACS), and including Kathryn J. Ruddy, MD, MPH, of the Mayo Clinic Comprehensive Cancer Center, a former NCCN Foundation®Young Investigator Award recipient—used data from the National Cancer Database (NCDB) to review results for women across the United States, age 18-62, who were diagnosed with this type of breast cancer between 2010 and 2018. 19,248 of the patients lived in Medicaid expansion states, while 12,153 resided in non-expansion locations. In the expansion states, the 2-year survival rate increased from the 2010 baseline rate of 93.9% to 95.0% across the study period. However, in the non-expansion states, 2-year survival declined slightly from 94.0% to 93.9%. The biggest difference was seen in patients with Stage III disease.
“Expanding Medicaid to the 10 states that have yet to do so can help ensure that more patients with cancer benefit from life-saving treatments,” said lead researcher Kewei Sylvia Shi, MPH, Surveillance and Health Equity Science, American Cancer Society. “It’s crucial to increase access to oncology services, expand insurance coverage, and streamline diagnostic and referral processes. Stage III cancer represents a critical point in disease presentation and can further progress and become incurable if undertreated. Having health insurance coverage will make it more likely for these patients to receive timely and comprehensive access to life-saving therapies, have better medication adherence, and complete treatment, which leads to better survival outcomes.”
HR-negative, HER2-positive breast cancer is an aggressive subtype that accounts for approximately 5% of all breast cancer diagnoses.1 This is the first study to focus on the impact of Medicaid expansion on that specific population.
The study found that treatment according to recommendations from evidence-based, expert consensus driven clinical practice guidelines—such as the National Comprehensive Cancer Network® (NCCN®) Clinical Practice Guidelines in Oncology (NCCN Guidelines®)— was more likely to begin within 90 days from diagnosis in the expansion states.
“This study reinforces the important role Medicaid expansion plays in ensuring that women newly diagnosed with HR-negative, HER2-positive breast cancer have equitable access to the healthcare services they need—especially when prognosis depends on access to treatment,” said Millicent Gorham, CEO of the Alliance for Women’s Health and Prevention, who was not involved in this research. “Breast cancer is far too common, and rates are increasing among younger women, making it critical that policymakers also prioritize women’s access to preventive health screenings and appropriate treatments.”
AboutJNCCN—Journal of the National Comprehensive Cancer Network
More than 25,000 oncologists and other cancer care professionals across the United States read JNCCN—Journal of the National Comprehensive Cancer Network. This peer-reviewed, indexed medical journal provides the latest information about innovation in translational medicine, and scientific studies related to oncology health services research, including quality care and value, bioethics, comparative and cost effectiveness, public policy, and interventional research on supportive care and survivorship. JNCCN features updates on the NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines®), review articles elaborating on guidelines recommendations, health services research, and case reports highlighting molecular insights in patient care. JNCCN is published by Harborside/BroadcastMed. Visit JNCCN.org. To inquire if you are eligible for a FREE subscription to JNCCN, visit NCCN.org/jnccn/subscribe. Follow JNCCNat x.com/JNCCN.
About the National Comprehensive Cancer Network
The National Comprehensive Cancer Network® (NCCN®) is a not-for-profit alliance of leading cancer centers devoted to patient care, research, and education. NCCN is dedicated to improving and facilitating quality, effective, equitable, and accessible cancer care so all patients can live better lives. The NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines®) provide transparent, evidence-based, expert consensus recommendations for cancer treatment, prevention, and supportive services; they are the recognized standard for clinical direction and policy in cancer management and the most thorough and frequently-updated clinical practice guidelines available in any area of medicine. The NCCN Guidelines for Patients® provide expert cancer treatment information to inform and empower patients and caregivers, through support from the NCCN Foundation®. NCCN also advances continuing education, global initiatives, policy, and research collaboration and publication in oncology. Visit NCCN.org for more information.
Association of Medicaid Expansion With Timely Receipt of Treatment and Survival Among Patients With HR-Negative, HER2-Positive Breast Cancer
Article Publication Date
24-Oct-2024
COI Statement
Dr. Castellino has disclosed serving as a scientific advisor for Seattle Genetics. Dr. Yabroff has disclosed serving as a scientific advisor for Flatiron Health. Dr. Han has disclosed receiving grant/research support from AstraZeneca. The remaining authors have disclosed that they have not received any financial consideration from any person or organization to support the preparation, analysis, results, or discussion of this article
UMD researcher trains AI to predict diarrheal outbreaks related to climate change
New study uses AI models to create early warning system for disease outbreaks resulting from climate change-related extreme weather
University of Maryland
Climate change-related extreme weather, such as massive flooding and prolonged drought, often result in dangerous outbreaks of diarrheal diseases particularly in less developed countries, where diarrheal diseases is the third leading cause of death among young children. Now a study out Oct. 22, 2024, inEnvironmental Research Letters by an international team of investigators led by senior author from University of Maryland’s School of Public Health (UMD SPH) Amir Sapkota, offers a way to predict the risk of such deadly outbreaks using AI modeling, giving public health systems weeks or even months to prepare and to save lives.
“Increases in extreme weather events related to climate change will only continue in the foreseeable future. We must adapt as a society,” said Sapkota, who is chair of the SPH Department of Epidemiology and Biostatistics. “The early warning systems outlined in this research are a step in that direction to enhance community resilience to the health threats posed by climate change.”
The multidisciplinary team, working across several institutions, relied on temperature, precipitation, previous disease rates, El Niño climate patterns as well as other geographic and environmental factors in three countries - Nepal, Taiwan, and Vietnam - between 2000 and 2019. Using this data, the researchers trained AI-based models that can predict area-level disease burden with weeks to months ahead of time.
“Knowing expected disease burden weeks to months ahead of time provides public health practitioners crucial time to prepare. This way they are better prepared to respond, when the time comes” Sapkota said.
While the study focused on Nepal, Vietnam, and Taiwan, “our findings are quite applicable to other parts of the world as well, particularly areas where communities lack access to municipal drinking water and functioning sanitation systems,” said lead author of the study Raul Curz-Cano, Associate Professor at Indiana University School of Public Health in Bloomington.
Sapkota says AI’s ability to work with huge data sets means that this study is an early step among many he anticipates will result in increasingly accurate predictive models for early warning systems. He hopes this will allow public health systems to prepare communities to protect themselves from a heightened risk of diarrheal outbreaks.
The team responsible for the research came from a wide variety of fields, including atmospheric and oceanic science, community health research, water resources engineering and beyond. The research team was comprised of authors from UMD – including its Department of Epidemiology and Biostatistics and Department of Atmospheric and Oceanic Science – and from Indiana University School of Public Health in Bloomington, the Nepal Health Research Council, the Hue University of Medicine and Pharmacy in Vietnam, Lund University in Sweden, and Chung Yuan Christian University in Taiwan.
This work was supported by grants from the National Science Foundation through Belmont Forum (award number (FAIN): 2025470) and by Swedish Research Council for Health, Working Life and Welfare (Forte: 2019-01552); Taiwan Ministry of Science and Technology (MOST 109-2621-M-033-001-MY3 and MOST 110- 2625-M-033-002); and National Science Foundation National Research Traineeship Program (NRT-INFEWS:1828910).
To request an interview with Dr. Sapkota, please reach out to sph-comm@umd.edu.
Journal
Environmental Research Letters
Method of Research
Computational simulation/modeling
Article Title
A prototype early warning system for diarrhoeal disease to combat health threats of climate change in the asia-pacific region
Article Publication Date
22-Oct-2024
A natural climate change laboratory in Japan reveals the adaptation dynamics of fishers
A new scientific study reveals the complex relationship between the impacts of climate change and the adaptive responses of coastal fishers in the southern coasts of Japan.
National Institute for Environmental Studies
A new scientific study published this Wednesday in the journal People and Nature reveals the complex relationship between the impacts of climate change and the adaptive responses of coastal fishers in one of the areas most affected by these environmental changes: the southern coasts of Japan. Warming waters and strong currents flowing northward are rapidly transforming the macroalgal beds along these coasts, as reef-building corals, subtropical herbivorous fish, and other warm-water species expand their territory northward. This global phenomenon, known as tropicalization, is threatening temperate ecosystems worldwide, from macroalgal beds in Japan and Australia to seagrass meadows in the Gulf of Mexico and the Mediterranean, altering the composition of species and the services these ecosystems provide. However, there is little evidence on how these fishing communities are being affected and how they are adapting to these changes, making adaptive management difficult. This research contributes to filling that gap in science and policy.
The study was part of an international Ph.D. conducted by the lead author, Dr. Xochitl Édua Elías Ilosvay, in the research group Future Oceans Lab at CIM-University of Vigo (Spain), under the supervision of researchers Elena Ojea, head of this research team at UVigo's Marine Research Center (CIM), and Jorge García Molinos, from Hokkaido University in Japan. It also involved collaboration with Naoki H. Kumagai from Japan’s National Institute for Environmental Studies, participation from Japanese researchers at the Kuroshio Biological Research Institute, and support from local community members, Kameyuki Seike and Kazuki Seike, during field studies.
Personal interviews with over one hundred fishers from Shikoku
The researchers involved in this project conducted in-person interviews with over a hundred fishers from 25 fishing communities along the entire west coast of Shikoku, Japan’s fourth-largest island. These communities are located in three regions that vary in their exposure to tropicalization, ranging from ecosystems entirely dominated by tropical corals in the south, to mixed ecosystems in the central region, and the last remaining temperate macroalgal beds in the north. "These fishing communities provided a natural laboratory to understand to what extent adaptation responses reflect the natural gradient of exposure to ecological changes," explains Xochitl E. Elías, adding that the goal of the study was to assess whether the adaptation responses of fishers were more influenced by the intensity of ecological change (referred to as the "adaptation continuum") or by their socio-economic context.
The results showed that while fishers in the central region, where tropicalization is more dynamic, mainly adopted adaptation strategies ("such as reducing fishing expenses or seeking new species," as the authors explain in the article), in the other two regions, non-action responses predominated. The prevalence of inaction in the southern region, where tropical changes have been present for longer, contradicts the idea of an adaptation continuum, which suggests that as impacts increase, fishers should transition from adaptation strategies to deeper transformations when these strategies are no longer sufficient.
The authors attribute this result to the fact that transformative responses in the south, such as abandoning fishing, may have occurred earlier (only active fishers were interviewed), which is supported by the decline in the fishing population in the region. However, the level of exposure did not clearly influence the fisher’s willingness to implement transformative changes. That willingness was more related to their social and economic circumstances. Specifically, households that relied primarily on fishing for income and food were more likely to adapt but less likely to transform, while fishers involved in coastal aquaculture were more willing to make profound changes than those engaged in extractive fishing. This finding highlights the need to address climate change mitigation and social adaptation simultaneously.
Importance of anticipating and implementing adaptive strategies
In a country where coastal fishing and aquaculture represent nearly half of the total fishing production and significantly contribute to employment in the sector, these results underscore the importance of integrating environmental, socio-economic, and cultural considerations into policies that aim to protect the livelihoods of fishers from environmental changes. Globally, the study emphasizes the value of conducting research in climate change hotspots to offer insights that can help anticipate and implement adaptive and transformative strategies in other regions of the world that will inevitably face the impacts of climate change in the future.
A study published today in IOP Publishing’s journal Environmental Research Letters, has revealed a staggering $79 billion in annual climate-related costs from the production of common materials in the United States. These costs, which stem from greenhouse gas emissions, are not reflected in current market prices, effectively creating a massive subsidy for carbon-intensive industries.
“High price point is a common reason why low emission alternative materials are not adopted voluntarily by industries. Accounting for the externalized cost of emissions could provide an economic basis for driving innovation and implementation of alternative material production methods”, says lead author Elisabeth Van Roijen, PhD, University of California Davis.
The research, conducted by researchers at the University of California, Davis, examines nine widely used materials: asphalt, plastics, brick, glass, cement, lime, gypsum, steel, and aluminium. By analysing production data, energy consumption, and emissions factors, the researchers calculated both the energy-related (e.g. as required for high temperature processes) and process-related (e.g. resulting from chemical reactions) carbon dioxide emissions for each material.
Key findings include:
These nine materials resulted in 427 million metric tons of CO2 emissions in 2018.
If the climate costs from these emissions were factored into prices, some materials would see significant cost increases:
o Cement: 62% increase
o Lime: 61% increase
o Gypsum: 47% increase
o Steel: 22%
o Plastics: 19%
Steel and plastics, despite climate-related costs constituting a lower fraction of their market value, are each responsible for over $20 billion in annual climate costs due to their high production volumes.
The study used the U.S. Environmental Protection Agency's Social Cost of Carbon (SCC) estimate of $184 per ton of CO2 to calculate the climate-related costs. This figure captures the quantifiable economic damage associated with increased carbon emissions, including impacts on human health, agriculture, and coastal infrastructure.
Incorporating these climate costs into material prices could drive innovation in low-carbon production methods and increase the competitiveness of recycling and alternative materials. For example, if aluminium and steel production transitioned entirely to renewable energy sources, their climate-related costs would decrease by 95% and 79%, respectively.
The report emphasizes the policy implications of the findings and the need for coordinated international action. Such materials pricing occurring only in the US could result in increased imports of lower cost, higher carbon-emitting materials from other countries.
Targeted policies are needed to address the process-related emissions (such as chemical reactions in cement and lime) that cannot be eliminated by switching to clean energy sources. Improved recycling rates, extended producer responsibility laws, and alternative materials could all play a role in reducing emissions.
As global material demand continues to grow, particularly in developing economies, the researchers call for further research into policy solutions to address the climate impacts of material production and use in a global and coordinated manner.
ENDS
About IOP Publishing IOP Publishing is a society-owned scientific publisher, delivering impact, recognition and value to the scientific community. Its purpose is to expand the world of physics, offering a portfolio of journals, ebooks, conference proceedings and science news resources globally.
IOPP is a member of Purpose-Led Publishing, a coalition of society publishers who pledge to put purpose above profit.
As a wholly owned subsidiary of the Institute of Physics, a not-for-profit society, IOP Publishing supports the Institute’s work to inspire people to develop their knowledge, understanding and enjoyment of physics. Visit ioppublishing.org to learn more.
About the University of California, Davis Located near California's state capital, UC Davis is a renowned public land-grant and Tier 1 research university, and one of the 10 campuses in the University of California system. With an annual research budget exceeding $1 billion, the university is home to a comprehensive health system and nearly two dozen specialized research centers. Serving over 40,000 students, UC Davis offers more than 100 undergraduate majors and provides interdisciplinary graduate education through four colleges and six professional schools. For the eighth consecutive year, UC Davis has been named the greenest campus in the United States by the 2023 UI GreenMetric World University Rankings. The university ranks as the world’s fifth most sustainable campus, marking the 10th consecutive year it has placed in the global top five.
When we disturb the seabed, we get more carbon dioxide and increase the risk of oxygen depletion
A new study from Aarhus University shows that disturbances of the seabed from trawling equipment and dredging can lead to a series of negative consequences for both the marine environment and the global ecosystem.
Aarhus University
image:
Six mussel trawlers at Venø in the Limfjord pull large amounts of seabed up into the water column. The cloud of sediment (seabed) leads to an increased release of carbon dioxide and causes poorer oxygen conditions over the seabed.
The seabed holds a large amount of carbon and nutrients. Globally, the seabed contains much more carbon than is present as carbon dioxide in the atmosphere.
Now, a brand-new study, recently published in the scientific journal 'Estuarine, Coastal and Shelf Science,' shows that repeated disturbances of the seabed release some of the stored carbon and nitrogen into the ocean.
This acts as an additional source of the greenhouse gas carbon dioxide and leads to increased oxygen consumption at the seabed.
Carbon from the seabed is converted in sediment clouds In the seabed – or sediment, as researchers call it – large amounts of carbon are stored in organic compounds derived from plankton, plants, and animals. Much of this organic carbon has been preserved in the seabed for hundreds of years.
There are also large pools of nutrients such as nitrogen and phosphorus. These are partly bound to organic compounds and partly found as dissolved nutrient salts, which are directly available for marine plankton organisms and larger plants.
'Researchers have long assumed that physical disturbances of the seabed, such as from fishing equipment like trawling, increase the conversion of organic carbon into carbon dioxide, but theoretical models have lacked documentation in the form of measured values. We have now shown through laboratory experiments that this is indeed the case,' explains senior researcher Christian Lønborg, Institute for Ecoscience, Aarhus University, who led the study.
In the laboratory experiments, where the seabed was disturbed several times over a period of about four months, the researchers measured that the conversion of carbon and the release of nitrogen increased when the seabed was stirred into a plume, as happens during trawling.
More carbon dioxide and less oxygen Human activities, such as trawling and dreading, stir the seabed into the water column. This accelerates the degradation of organic material, releasing both carbon dioxide and nutrients.
The additional production of the greenhouse gas carbon dioxide is an increased burden on the climate and thus affects the global environment.
When nutrients are released, they can potentially stimulate algae growth in coastal waters. As algae produce organic carbon, this provides an additional input of carbon that needs to be processed at the seabed.
The turnover of organic matter in the water consumes oxygen. And disturbances to the seabed therefore contribute to poorer oxygen conditions in the water immediately above the seabed. Disturbances of the seabed can therefore potentially contribute to the loss of oxygen that often occurs during late summer in Danish waters.
'If we are to assess the impact of trawling equipment, dredging, and extraction of raw materials from the seabed, these consequences must also be considered.' says Christian Lønborg.
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