Tag Archives: fish

Aquatic plant reduces antibiotics in water and genetic damage in fish, but risks remain

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A new study from researchers at the University of São Paulo has shed light on a growing environmental concern: the presence of antibiotic residues in freshwater systems, and their impact on aquatic life and potentially human health.

The research, conducted in Brazil’s Piracicaba River basin, found traces of multiple commonly used antibiotics in water, sediments, and fish. Scientists also explored whether a floating aquatic plant, Salvinia auriculata, could help reduce this contamination. The findings suggest it can—but not without complications.

Pollution Builds Up in Dry Seasons

The team, led by Patrícia Alexandre Evangelista, monitored samples from a region near the Santa Maria da Serra dam, where pollutants from across the river basin tend to accumulate. The area receives runoff from urban sewage, agriculture, aquaculture, and livestock farming.

Twelve antibiotics, including tetracyclines, fluoroquinolones, sulfonamides, and phenols, were tracked across both rainy and dry seasons. A clear pattern emerged: during the rainy season, most antibiotics were barely detectable, likely diluted by higher water volumes. In the dry season, however, concentrations rose significantly as water levels dropped and pollutants became more concentrated.

Sediments, rich in organic matter and minerals, acted as reservoirs for these compounds, storing them and potentially releasing them back into the environment over time.

Contaminated Fish Raise Health Concerns

One of the study’s most striking findings was the detection of chloramphenicol, a banned veterinary antibiotic, in lambari fish collected from local fishermen. The substance appeared only during the dry season, but at levels significant enough to raise concern.

Because this species is widely consumed in the region, researchers flagged a possible route of human exposure through food.

A Plant-Based Solution, With Limits

The study also tested whether Salvinia auriculata, a fast-growing floating plant often considered a nuisance, could help remove antibiotics from contaminated water.

In controlled experiments, the plant proved highly effective at absorbing enrofloxacin, eliminating more than 95% of it within days under certain conditions. Its performance was less impressive with chloramphenicol, removing only 30% to 45%, and over a longer period.

The antibiotics were found to accumulate mainly in the plant’s roots, suggesting that filtration and absorption at the root level play a key role.

A Complex Ecological Trade-Off

However, the picture is not straightforward. Even when the plant reduced antibiotic levels in the water, fish did not always benefit. In some cases, absorption rates in fish actually increased, possibly because the plant altered the chemical form of the antibiotics, making them easier for organisms to absorb.

Chloramphenicol, in particular, showed a strong tendency to persist in fish tissue, with a half-life exceeding 90 days. Enrofloxacin, by contrast, was eliminated more quickly and showed lower accumulation.

The study also examined genetic damage in fish. Chloramphenicol exposure led to increased DNA damage, but this effect was reduced when the plant was present, suggesting a possible protective role. No similar benefit was observed for enrofloxacin.

Not a Silver Bullet

Researchers caution against viewing Salvinia auriculata as a simple fix. While it can reduce antibiotic levels, it may also change how these substances behave in the ecosystem. There are additional concerns about how to safely dispose of contaminated plant biomass, which could otherwise reintroduce pollutants.

Still, the findings point to the potential of low-cost, nature-based solutions in regions where advanced water treatment technologies are not feasible.

Bigger Picture: A Growing Environmental Threat

The presence of antibiotics in rivers is more than just a local issue. It contributes to the broader global challenge of antimicrobial resistance, raising the risk of so-called “superbugs” emerging in natural environments.

As co-author Valdemar Luiz Tornisielo noted, the study underscores both the scale of human impact on ecosystems and the need for integrated solutions that consider not just pollutant removal, but long-term ecological effects.

In essence, the research reveals a problem that is measurable and widespread—and solutions that are promising, but far from simple.

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‘Plenty of fish in the sea’? Not anymore, say UN experts in Nice

Seals Can Serve As ‘Smart Sensors’ to Know Fish Populations in Ocean’s Twilight Zone: Study

‘Plenty of fish in the sea’? Not anymore, say UN experts in Nice

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As yachts bobbed gently and delegates streamed by in a rising tide of lanyards and iPads at Port Lympia, Nice’s historic harbor, that statistic sent a ripple through the summit’s third day – a stark reminder that the world’s oceans are under growing pressure from overfishing, climate change, and unsustainable management.

Presented dockside at a press conference by Manuel Barange, Assistant Director-General of the UN Food and Agriculture Organization (FAO), the report offered a detailed global snapshot of how human activity is steadily draining the ocean – and how sound management can bring it back.

“To use a banking comparison,” Mr. Barange told UN News in an interview ahead of the report’s launch, “we are extracting more than the interest the bank gives us. We are depleting the populations.”

The “Review of the State of World Marine Fishery Resources 2025,” which draws on data from 2,570 marine fish stocks – the widest scope used by FAO yet – paints a complex picture: while over a third of stocks are being overexploited, 77 per cent of fish consumed globally still come from sustainable sources thanks to stronger yields from well-managed fisheries.

“Management works,” Mr. Barange said. “We know how to rebuild populations.”

Assistant Director-General Manuel Barange, of the Food and Agriculture Organization (FAO), unveiled the agency’s report on the world’s fish stocks.

A global patchwork

Regional disparities remain stark. In the Pacific coast of the United States and Canada, over 90 per cent of stocks are sustainably fished. In Australia and New Zealand, the figure exceeds 85 per cent. The Antarctic – governed by strict international regulations – reports 100 per cent sustainability.

But along northwest Africa’s coast, from Morocco to the Gulf of Guinea, over half of all stocks are overfished, with little sign of recovery. The Mediterranean               Seas fare even worse: 65 per cent of stocks there are unsustainable. Yet there is a positive sign – the number of boats going out to fish in that region has declined by nearly a third over the past decade, offering hope that policy shifts are beginning to take effect.

For Mr. Barange, the lesson is clear: where management systems exist – and are backed by resources – stocks recover.

But science-based management is expensive. “Some regions can’t afford the infrastructure needed for control and monitoring, the science needed, the institutions needed,” he said.

“We need to build up capacity for the regions that are not doing so well. Not to blame them, but to understand the reasons why they are not doing so well and support them in rebuilding their populations.”

From collapse to comeback

Perhaps the clearest example of recovery may be tuna. Once on the brink, the saltwater fish has made a remarkable comeback. Today, 87 per cent of major tuna stocks are sustainably fished, and 99 per cent of the global market comes from those stocks.

“This is a very significant turnaround,” Mr. Barange said. “Because we have taken management seriously, we have set up monitoring systems, we set up management systems, compliance systems.”

The full findings in the FAO’s new report are likely to shape policy discussions far beyond Nice. The agency has worked closely with 25 regional fisheries-management organizations to promote accountability and reform, and Mr. Barange believes the model is replicable – if the political will holds.

Fish, livelihoods, and the blue economy

Countries were reported to have finalized negotiations over the political declaration expected to be adopted on Friday at the close of UNOC3, as the conference in known. The statement will form part of the Nice Ocean Action Plan and is intended to align with the Kunming-Montreal Global Biodiversity Framework – the 2022 agreement to protect 30 per cent of the planet’s land and ocean by 2030.

As the heat climbed once again over the stone quays of Nice – a city perched in one of Europe’s most climate-vulnerable regions – sustainable fisheries took center stage inside the conference halls. Action panels focused on supporting small-scale fishers and advancing inclusive ocean economies, with delegates exploring how to align conservation goals with social equity – especially in regions where millions depend on fishing for survival.

‘We’re not apart from the ocean – we’re a part of it’ – FAO’s Manuel Barange

“There are 600 million people worldwide who depend on fisheries and aquaculture for their livelihoods,” Mr. Barange said. “In some countries, aquatic animals are the main source of protein. We’re not apart from the ocean – we’re a part of it.”

As the conference moves into its final stretch, FAO’s warning shines like a beacon: one-third of the world’s fish stocks remain under too much pressure. But the data also offer something that can be elusive in the climate and biodiversity space – evidence that recovery is possible.

Three days in, the FAO report underscores a central message voiced by UN Secretary-General António Guterres, on Monday, as he opened the summit: recovery is still within reach.

“What was lost in a generation,” he said, “can return in a generation.”

Health: Which grains you eat can impact your risk of getting heart disease earlier

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In one of the first studies to examine the relationship between different types of grain intake and premature coronary artery disease in the Middle East, researchers found a higher intake of refined grain was associated with an increased risk of premature coronary artery disease in an Iranian population, while eating whole grains was associated with reduced risk.

According to the researchers, previous epidemiological studies have reported an association between different types of grain intake with the risk of coronary artery disease. The current study evaluated the association between refined and whole grains consumption and risk of PCAD in an Iranian population.

Premature coronary artery disease (PCAD) refers to atherosclerotic narrowing of coronary arteries in males under 55 years old or in females under 65 years old. It is often asymptomatic early in the course of the disease but may lead to chest pain (angina) and/or heart attack with progressive development of narrowing (stenosis) or plaque rupture of the arterial wall. Risk factors for PCAD include smoking, high cholesterol, high blood pressure and diabetes.

Millets-Grains

“There are many factors involved in why people may be consuming more refined grains as opposed to whole grains and these cases differ between people, but some of the most important factors to consider include the economy and income, job, education, culture, age and other similar factors,” said Mohammad Amin Khajavi Gaskarei, MD, of the Isfahan Cardiovascular Research Center and Cardiovascular Research Institute at Isfahan University of Medical Sciences in Isfahan, Iran, and the study’s lead author. “A diet that includes consuming a high amount of unhealthy and refined grains can be considered similar to consuming a diet containing a lot of unhealthy sugars and oils.”

Whole grains are defined as containing the entire grain, while refined grains have been milled—ground into flour or meal—to improve shelf life but they lose important nutrients in the process. The 2019 ACC/American Heart Association Guideline on the Primary Prevention of Cardiovascular Disease recommends a diet that emphasizes the intake of vegetables, fruits, legumes, whole grains and fish to decrease heart disease risk factors.

The study recruited 2099 individuals with PCAD from hospitals. Participants were given a food frequency questionnaire for dietary assessments to evaluate dietary behaviors and evaluate the association between whole grain and refined grain intake and the risk of PCAD in individuals without a prior diagnoses of heart disease. After adjusting for confounders, a higher intake of refined grains was associated with an increased risk of PCAD, while whole grain intake was inversely related to reduced risk of PCAD.

“As more studies demonstrate an increase in refined grains consumption globally, as well as the impact on overall health, it is important that we find ways to encourage and educate people on the benefits of whole grain consumption,” Khajavi Gaskarei said. “Tactics to consider include teaching improved dietary choices in schools and other public places in simple language the general population can understand, as well as on television programs and by continuing to do high level research that is presented at medical conferences and published in medical journals. Clinicians must also be having these conversations with each other and their patients.”

Meal timing may influence mood vulnerability; Daytime eating benefits mental health

 

Clarifying the chaos of narwhals behavior; what are narwhals, how they help [Details]

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Researchers have used the mathematical equations of chaos theory to analyse the data from long-term monitoring of an electronically tagged narwhal. They have extracted previously undetected diurnal patterns within what initially appeared to be irregular diving and surface resting behavior, using records extending across 83 days.

“While animal-borne ocean sensors continue to advance and collect more data, there is a lack of adequate methods to analyse records of irregular behavior,” says Hokkaido University geophysicist Evgeny A. Podolskiy, first author of the research published in the journal PLOS Computational Biology.

Podolskiy developed the procedure to find behavioral patterns in seemingly intractable complexity with Mads Peter Heide‐Jørgensen at the Greenland Institute of Natural Resources.

Narwhals (Monodon monoceros) are relatively small whales found in Arctic seas, famous for their long single tusks and called the unicorns of the sea. They are one of the most endangered Arctic species due to climate change, human activity, and predation by such invasive species as killer whales. The narwhals are notable for undertaking dives to extreme depths of more than 1,800 metres. Their life cycle is tightly coupled with sea ice, which is rapidly declining.

A pod of adult male narwhals, Greenland, September 2019 (Photo: Carsten Egevang; This image may exclusively be used in relation to this press release. The image can not be included in media archives for use apart from the above and not be handed over to third parties, without prior acceptance by the photographer)./CREDIT: Carsten Egevang

Podolskiy and Heide‐Jørgensen combined their expertises in signal processing and biologging to understand the full diversity of behaviors of a satellite-tagged narwhal. Mathematical techniques developed as part of chaos theory can interpret complicated and seemingly chaotic behavior in dynamic systems to reveal states called ‘attractors’, which the systems tend to develop towards. In essence, the approach identifies significant patterns that would otherwise be difficult to detect.

The analysis of the behavior of the electronically tagged narwhal, inspired by Podolskiy’s previous work on turbulence, revealed a daily pattern of activity and how it was affected by changing seasons, features of narwhal behavior that were previously unrecognised. The animal rested nearer to the surface around noon, but when they did dive at that time the dives were very deep. During twilight and at night the dives became more shallow but also more intense, possibly due to hunting for squid, which is known for diurnal vertical migration. It was also found that increased sea ice constrains the narwhal’s surface activity, and is correlated with more intense diving.

“Our approach is relatively simple to implement and can map and label long term data, identifying differences between the behavior of individual animals and different species, and also detecting perturbations in behavior caused by changing influences,” the authors suggest.

The researchers expect that their new method may be especially useful for assessing the challenges to narwhals and other Arctic animals posed by climate change and the loss of sea ice. Such information may prove vital in adopting policies to protect endangered species in the face of natural change and increased human activity.

Related: http://dx.doi.org/10.1371/journal.pcbi.1010432

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Scientists take a deep dive into how ‘elasmobranchs’ use the ocean depth

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Using sophisticated electronic tags, scientists have assembled a large biologging dataset to garner comparative insights on how sharks, rays, and skates – also known as “elasmobranchs” – use the ocean depths. While some species spend their entire lives in shallow waters close to our shores on the continental shelf, others plunge hundreds of meters or more off the slope waters into the twilight zone, beyond where sunlight penetrates. This new understanding of how elasmobranchs use the ocean will enable policymakers and resource managers the opportunity to examine the threats these animals face, and guide future management and conservation plans.

A study published Aug. 19 in Science Advances, led by Stanford University and ZSL (Zoological Society of London) researchers, is the largest global investigation of where and when a diverse group of elasmobranchs move vertically. A team of 171 researchers from 135 institutions across 25 countries brought together two decades of data from satellite and archival tags that remotely tracked the movements and behaviors of 38 species in oceans across the globe.

“For the first time, we have a standardized, global database that we used to fill important knowledge gaps about the diving behaviors of sharks and rays,” said Samantha Andrzejaczek, co-lead author of the study and a postdoctoral research fellow at the Hopkins Marine Station of Stanford University. “This will enable better understanding of what fisheries interact with elasmobranchs and how to improve management of many of these long-lived animals.”