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VKM has assessed the positive and negative effects on biodiversity were sterile salmon to be used in Norwegian aquaculture. Triploidisation is assessed as the most effective method for sterilising fish, but it can affect the welfare and health of the fish.
Several other techniques for producing sterile salmon are being tested, but it is too early to determine whether they can be used in large-scale farming.
This is the key message in a knowledge summary VKM has prepared for the Norwegian Environment Agency.
Background
Escaped farmed salmon poses a major threat to wild salmon in Norway. hey can interbreed with wild salmon, genetically alter them, and make the populations less adaptable and more vulnerable to disease and environmental changes. A possible solution to the problem may be to use sterile salmon in farming.
To date, only triploidisation has been tested. Newly fertilised eggs are given a hydrostatic pressure shock, thereby retaining an extra set of chromosomes which render the fish sterile. This method is currently the only one tested on a large scale. Triploidisation is effective but can also pose health and welfare challenges to fish.
Methods
VKM has reviewed available scientific literature regarding methods that can be used to produce sterile salmon. VKM has assessed whether these methods work as well, or better, than triploidy and whether they are likely to have fewer negative effects on fish welfare. Assessments have also been made of whether farmed fish treated with other sterilisation methods pose a greater or lesser threat to wild salmon than traditional farmed salmon.
VKM has looked at the possibilities for further development of the triploidisation technique and has also assessed various methods currently being tested for producing sterile fish. Some of these are still at the laboratory-testing stage, while others are approaching trials with release into sea-pens. VKM has grouped the different methods based on whether they cause permanent changes in the genome (so-called "knock-out" of important genes) or whether the changes only result in temporary blocking or downregulation of gene expression (so-called "knock-down").
Results
VKM concludes that triploidisation remains the most effective method and that there are possibilities to further develop this methodology through targeted breeding and adjustments in how the fish are kept. These measures can potentially solve the challenges for fish health and welfare. Using pure triploid female lines can also reduce some of the other challenges by preventing spawning interactions in rivers and reducing disease transmission to wild salmon.
Alternative sterilisation methods, such as gene editing, vaccination, and temporary downregulation of proteins for gonad development using antisense oligomers and egg immersion, are promising but still under development.
VKM assesses that methods causing permanent changes in the genome of diploid fish have a higher inherent risk than methods that only affect gene expression.
Hope in egg-bathing
Perhaps the most promising technique for safe production of sterile salmon is to add synthetic oligonucleotides to the eggs at an early stage, thereby preventing germ cell development without causing any inheritable changes. Such oligonucleotides can be injected into the eggs or absorbed by the eggs through bathing (immersion) in a special solution.
"Especially the method involving targeted 'tools,' such as oligonucleotides that prevent germ cell development and can be added to the eggs in a water bath, seems promising," says Johanna Bodin, member of the Panel for Genetically Modified organisms and spokesperson for the report.
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2025
Fungus-farming termites cultivate a Termitomyces fungus monoculture in enclosed gardens (combs) free of other fungi, except during colony declines, where Pseudoxylaria spp. stowaway fungi appear and take over combs. Here, we determined Volatile Organic Compounds (VOCs) of healthy Macrotermes bellicosus nests in nature and VOC changes associated with comb decay during Pseudoxylaria takeover. We identified 443 VOCs and unique volatilomes across samples and nest volatilomes that were mainly composed of fungus comb VOCs with termite contributions. Few comb VOCs were linked to chemical changes during decay, but longipinocarvone and longiverbenone were only emitted during comb decay. These terpenes may be involved in Termitomyces defence against antagonistic fungi or in fungus-termite signalling of comb state. Both comb and Pseudoxylaria biomass volatilomes contained many VOCs with antimicrobial activity that may serve in maintaining healthy Termitomyces monocultures or aid in the antagonistic takeover by Pseudoxylaria during colony decline. We further observed a series of oxylipins with known functions in the regulation of fungus germination, growth, and secondary metabolite production. Our volatilome map of the fungus-farming termite symbiosis provides new insights into the chemistry regulating complex interactions and serves as a valuable guide for future work on the roles of VOCs in symbioses.
2025
2025
Per- and polyfluoroalkyl substances (PFAS) have gained significant global attention due to their extensive industrial use and harmful effects on various organisms. Among these, perfluoroalkyl acids (PFAAs) are well-studied, but their diverse precursors remain challenging to monitor. The Total Oxidizable Precursor (TOP) assay offers a powerful approach to converting these precursors into detectable PFAAs. In this study, the TOP assay was applied to samples from the East Asian-Australian Flyway, a critical migratory route for millions of shorebirds. Samples included shellfish from China's coastal mudflats, key stopover sites for these birds, and blood and liver samples from shorebirds overwintering in Australia. The results showed a substantial increase in perfluorocarboxylic acids (PFCAs) across all sample types following the TOP assay, with the most significant increases in shorebird livers (Sum PFCAs increased by 18,156 %). Intriguingly, the assay also revealed unexpected increases in perfluorosulfonic acids (PFSAs), suggesting the presence of unidentified precursors. These findings highlight the need for further research into these unknown precursors, their sources, and their ecological impacts on shorebirds, other wildlife, and potential human exposure. This study also provides crucial insights into the TOP assay’s strengths and limitations in studying PFAS precursor dynamics in biological matrices.
2025
State of the Climate in 2024: The Arctic
The Arctic environment in 2024 continued on a trajectory that has put it in a state far different from that of the twentieth century. Ongoing accumulation of greenhouse gases in the atmosphere continues to quickly warm the Arctic, resulting in rapid changes in the cryosphere that are driving cascading impacts to climate, ecological, and societal systems.
Many weather- and climate-related impacts in the Arctic are the result of compounding change, such as increased riverbank erosion, which is proximately due to increased river discharge from higher seasonal precipitation, yet is also exacerbated by thawing permafrost. However, even individual storms occur within very different ocean and ice conditions than were typically present in the late twentieth century. As a result, the impacts, including high winds, excessive precipitation, and coastal inundation, may be quite different nowadays, as exemplified by the October 2024 storm in northwest Alaska that produced severe coastal flooding in several communities. To share some of these impacts with a wider audience, select extreme weather impacts around the greater Arctic have been highlighted through the inclusion of sidebars in recent State of the Climate Arctic chapters (e.g., Benestad et al. 2023; Thoman et al. 2024).
Average surface air temperatures for the Arctic overall (poleward of 60°N) for 2024 averaged 1.27°C above the 1991–2020 baseline average, the second-highest annual temperature since records began in 1900. For the 11th consecutive year, the Arctic annual temperature anomaly was larger than the global average anomaly. Seasonally, summer (July–September) 2024 ranked as the third-highest average temperature, and autumn (October–December) 2024 saw its highest average temperature on record. At the subseasonal scale, an intense August heatwave brought all-time record high temperatures to parts of the northwest North American Arctic. Closely but not completely tied to spring and summer air temperature trends, productivity of tundra and boreal forest vegetation has dramatically increased in recent decades. Overall “tundra greenness” was the fifth highest since 1982. However, local to regional “browning” (reduced vegetation productivity) shows that disturbance factors besides temperatures, such as wildfire, can be important.
Sea ice is one of the most iconic features of the Arctic environment and plays an important role in regulating global climate, regional ecosystems, and economic activities. Sea ice extent typically reaches the annual maximum in March, and in 2024 the maximum was near the 1991–2020 average overall, but somewhat below average in the Barents Sea and Gulf of St. Lawrence. The annual minimum sea ice extent occurs in September, and in 2024 the September monthly average was the sixth lowest in the 46-year satellite record. The Northern Sea Route along the north Russia coast opened later than the past 20 years’ average due to persistent ice in the southwest Chukchi Sea. The Northwest Passage’s southern route through northwest Canada opened again this year and, quite unusually, the deepwater northern route was also almost entirely ice free at the end of September.
Decreasing sea ice extent during the late spring and summer months exposes larger areas of ocean to direct warming during the time of year of high incoming solar radiation. Poleward of 65°N, open ocean surface temperatures typically peak in August. In 2024, late summer sea surface temperature anomalies showed significant regional variability, with the waters in the Barents and Kara Seas 2°C–4°C warmer than normal. In sharp regional contrast, Chukchi Sea sea surface temperatures were the lowest in more than 40 years, while just to the east, sea surface temperatures in the southern Beaufort Sea were significantly above the 1991–2020 average.
Like sea ice, permafrost (soils or other earth materials that have remained frozen for at least two years) is an important feature of Arctic environments that occurs widely on land and throughout some submarine continental shelf areas that were exposed land during the last Ice Age (about 15,000 years ago). Unlike many parts of the Arctic environmental system, permafrost temperatures and the summer surface thaw zone cannot be monitored from space-borne instruments and depend on in situ measurements. While long-term observations are not available over most of the Asian Arctic, observations elsewhere show multi-decade warming of deeper permafrost continuing across the Arctic, with some sites in North America and Svalbard having seen their highest temperatures on record in 2024. Overall, colder permafrost is warming more rapidly; areas where permafrost temperatures are close to freezing have slower rates of warming as ice changes phase to liquid water.
Precipitation monitoring in the Arctic has historically been limited due to the lack of in situ measurements over the Arctic Ocean, a sparse land station network, and significant problems with solid precipitation undercatch because of the inherent difficulties in capturing solid precipitation in strong wind environments. Recent advances in reanalyses that combine observations and computer simulations now allow for more robust regional-scale precipitation analysis and historical comparisons. In 2024, Arctic-wide annual precipitation was the third highest on record, and summer (July through September) precipitation was the highest since 1950. Rivers serve as regional integrators of precipitation. Arctic river discharge overall for both 2023 and 2024 was close to the 1991–2020 average, albeit with significant differences across basins. For example, in North America, Mackenzie River discharge was well below average in both years, but Yukon River discharge was above average in both years; most basins in Eurasia saw above-normal discharge in 2024 but below-average discharge in 2023.
In much of the Arctic, snow is the dominant form of precipitation for most of the year, and the presence or absence of snow cover is a critical factor in many climate and environmental processes. During the 2023/24 snow season, there were marked regional and continental scale differences in snow cover duration. The snow cover duration varied from the shortest to date in the twenty-first century over parts of Canada to at or near the longest in this century in parts of the Nordic and Asian Arctic.
Melt and discharge from the Greenland Ice Sheet play important roles in modulating North Atlantic weather and climate. In 2024, the total amount of ice decreased, as it has every year since the late 1990s, but the loss was 50%−80% less than the 2002 − 23 annual average. This was the result of an unusual but persistent weather pattern that inhibited the development and persistence of warm air masses over Greenland during the summer. Ongoing monitoring of the Greenland Ice Sheet, which holds enough water to raise global sea levels by more than seven meters if entirely melted, is critical for understanding drivers of melt and ice sheet dynamics.
The Arctic stratosphere experienced two major sudden warming events early in 2024 that resulted in enhanced ozone transport into the region from lower latitudes. As a result, surface ultraviolet radiation was reduced in parts of the Asian Arctic in spring and the central Arctic and North America in summer.
Special Notes: The 1991–2020 baseline is used in this chapter except where data availability requires use of a different baseline. This chapter includes a focus on Arctic river discharge (section 5h), which alternates yearly with a section on glaciers and ice caps outside of Greenland.
2025
Personalized approaches are required for stroke management due to the variability in symptoms, triggers, and patient characteristics. An innovative stroke recommendation system that integrates automatic predictive analysis with semantic knowledge to provide personalized recommendations for stroke management is proposed by this paper. Stroke exacerbation are predicted and the recommendations are enhanced by the system, which leverages automatic Tree-based Pipeline Optimization Tool (TPOT) and semantic knowledge represented in an OWL Ontology (StrokeOnto). Digital sovereignty is addressed by ensuring the secure and autonomous control over patient data, supporting data sovereignty and compliance with jurisdictional data privacy laws. Furthermore, classifications are explained with Local Interpretable Model-Agnostic Explanations (LIME) to identify feature importance. Tailored interventions based on individual patient profiles are provided by this conceptual model, aiming to improve stroke management. The proposed model has been verified using public stroke dataset, and the same dataset has been utilized to support ontology development and verification. In TPOT, the best Variance Threshold + DecisionTree Classifier pipeline has outperformed other supervised machine learning models with an accuracy of 95.2%, for the used datasets. The Variance Threshold method reduces feature dimensionality with variance below a specified threshold of 0.1 to enhance predictive accuracy. To implement and evaluate the proposed model in clinical settings, further development and validation with more diverse and robust datasets are required.
2025
Intrusion Detection Systems (IDS) are critical in safeguarding network infrastructures against malicious attacks. Traditional IDSs often struggle with knowledge representation, real-time detection, and accuracy, especially when dealing with high-throughput data. This paper proposes a novel IDS framework that leverages machine learning models, streaming data, and semantic knowledge representation to enhance intrusion detection accuracy and scalability. Additionally, the study incorporates the concept of Digital Sovereignty, ensuring that data control, security, and privacy are maintained according to national and regional regulations. The proposed system integrates Apache Kafka for real-time data processing, an automatic machine learning pipeline (e.g., Tree-based Pipeline Optimization Tool (TPOT)) for classifying network traffic, and OWL-based semantic reasoning for advanced threat detection. The proposed system, evaluated on NSL-KDD and CIC-IDS-2017 datasets, demonstrated qualitative outcomes such as local compliance, reduced data storage needs due to real-time processing, and improved adaptability to local data laws. Experimental results reveal significant improvements in detection accuracy, processing efficiency, and Sovereignty alignment.
2025
Sources of ultrafine particles at a rural midland site in Switzerland
Ultrafine particles (UFPs; i.e., atmospheric aerosol particles smaller than 100 nm in diameter) are known to be responsible for a series of adverse health effects as they can deposit in humans' bodies. So far, most field campaigns studying the sources of UFPs have focused on urban environments. This study investigates the outdoor sources of UFPs at the atmospheric monitoring station in Payerne, which represents a typical rural location in Switzerland. We aim to quantify the primary and secondary fractions of UFPs based on specific measurements between July 2020 and July 2021 complementing a series of operational meteorological, trace gas and in situ aerosol observations. To distinguish between primary and secondary contributions, we use a method that relies on measuring the fraction of non-volatile particles as a proxy for primary particles. We further compare our measurement results to previously established methods. We find that primary particles resulting from traffic and residential wood burning (direct emissions – mostly non-volatile BC-rich) contribute less than 40 % to the total number of UFPs, mostly in the Aitken mode. On the other hand, we observe local new particle formation (NPF) events (observed from ∼ 1 nm) evident from the increase in cluster ions (1.5–3 nm) and nucleation-mode particle (2.5–25 nm) concentrations, especially in spring and summer. These events, mediated by sulfuric acid, contribute to increasing the UFP number concentration, especially in the nucleation mode. Besides NPF, the chemical processing of particles emitted from multiple sources (including traffic and residential wood burning) contributes substantially to the nucleation-mode particle concentration. Under the present conditions investigated here, we find that secondary processes mediate the increase in UFP concentration to levels equivalent to those in urban locations, affecting both air quality and human health.
2025
This study builds upon the findings of a FAIRMODE intercomparison exercise conducted in a district of Antwerp, Belgium, where a comprehensive dataset of air pollutant measurements (air quality stations and passive samplers) was available. Long-term average NO2 concentrations at very high spatial resolution were estimated by several dispersion modelling systems (Martín et al., 2024) to investigate the ability of these to capture the detailed spatial distribution of NO2 concentrations at the microscale in urban environments. In this follow-up research, we extend the analysis by evaluating the capability of these modelling systems to predict the NO2 annual limit value exceedance areas (LVEAs) and spatial representativeness areas (SRAs) for NO₂ at two reference air quality stations. The different modelling approaches used are based on CFD, Lagrangian, Gaussian, and AI-driven models.
The different modelling approaches are generally good at predicting the LVEA and SRAs of urban air quality stations, although a small SRA (corresponding to low concentration tolerances or the traffic station) is more difficult to predict correctly. However, there are notable differences in performance among the modelling systems. Those based on CFD models seem to provide more consistent results predicting LVEAs and SRAs. Then, lower accuracy is obtained with AI-based systems, Lagrangian models, and Gaussian models with street canyon parameterizations. The Gaussian models with street-canyon parametrizations show significantly better results than models using simply a Gaussian dispersion parametrization.
Furthermore, little differences are observed in most of the statistical indicators corresponding to the LVEA and SRA estimates obtained from the unsteady full month CFD simulations compared to those from the scenario-based CFD simulation methodologies, but there are some noticeable differences in the LVEA or SRA (traffic station, 10 % tolerance) sizes. The number of scenarios does not seem to be relevant to the results. Different bias correction methodologies are explored.
2025
2025