The lichen Allocetraria madreporiformis in high-arctic steppes on Svalbard: a result of out-of-Tibet migration?

Published version available at: http://nhm2.uio.no/lichens/nordiclichensociety/Allocetraria madreporiformis is a small, finger-like, fruticose lichen with isolated occurrences in the inner fiord section of the long, straight fiord Wijdefjorden in Svalbard. Several new localities are added and mapped here, and we show that the species is confined to exclusive high-arctic steppe habitats on finetextured, moderately alkaline soil, exposed to wind erosion and aeolian transport of silt and sand. It avoids the most saline steppes and adjacent tundra areas, as indicated by numerous pH samples of mineral soils from sites with and without occurrences of A. madreporiformis. In this open habitat, all otherwise common arcticalpine fruticose lichen species were absent or extremely rare, and a cryptogamic cover was very depauperate. On Svalbard, this species is an exclusive character species of the steppe areas in Inner Wijdefjorden National Park. The genus Allocetraria is strongly centred in the Sino-Himalayan area. It is discussed here that it probably evolved as a response to the very extensive new habitats formed during a series of Qinghai-Tibetan Plateau uplift and orogeny events taking place 25–1.6 Ma. This and other aspects affecting current classification alternatives of cetrarioid lichens are also discussed. The habitat preferences of A. madreporiformis appear to have been largely defined by the conditions of its probable area of origin in steppe-like habitats of the northern part of the Qinghai-Tibetan Plateau

Natural variation in snow depth and snow melt timing in the High Arctic have implications for soil and plant nutrient status and vegetation composition

Snow cover is a key component in Arctic ecosystems and will likely be affected by changes in winter precipitation. Increased snow depth and consequent later snowmelt leads to greater microbial mineralization in winter, improving soil and vegetation nutrient status. We studied areas with naturally differing snow depths and date of snowmelt in Adventdalen, Svalbard. Soil properties, plant leaf nutrient status, and species composition along with the normalized difference vegetation index (NDVI) were compared for three snowmelt regimes (Early, Mid, and Late). We showed that (1) Late regimes (snow beds) had wetter soils, higher pH, and leaves of Bistorta vivipara (L.) Delarbre and Salix polaris Wahlenb. had higher concentration of nutrients (nitrogen and δ15N). Little to no difference was found in soil nutrient concentrations between snowmelt regimes. (2) Late regimes had highest NDVI values, whereas those of Early and Mid regimes were similar. (3) Vegetation composition differed between Early and Late regimes, with Dryas octopetala L. and Luzula arcuata subsp. confusa (Lange) characterizing the former and Equisetum arvense L. and Eriophorum scheuchzeri Hoppe the latter. (4) Trends for plant nutrient contents were similar to those found in a nearby snow manipulation experiment. Snow distribution and time of snowmelt played an important role in determining regional environmental heterogeneity, patchiness in plant community distribution, their species composition, and plant phenology

Using Ordinary Digital Cameras in Place of Near-Infrared Sensors to Derive Vegetation Indices for Phenology Studies of High Arctic Vegetation

We thank Mark Gillespie, Nanna Baggesen, and Anne Marit Vik for field assistance. The University in Svalbard (UNIS) provided logistical support. This work was funded by the Norwegian Research Council through the ‘SnoEco’ project (project No. 230970) and Arctic Field Grant (No. 246110/E10). It was supported by the ESA Prodex project ‘Sentinel-2 for High North Vegetation Phenology’ (contract No. 4000110654), the EC FP7 collaborative project ‘Sentinels Synergy Framework’ (SenSyF), funding from The Fram Centre Terrestrial Flagship, also from the EEA Norway Grants (WICLAP project, ID 198571), and from the GRENE Arctic Climate Change Research Project, Ministry of Education, Culture, Sports, Science and Technology in Japan.Peer reviewedPublisher PD

The northernmost hyperspectral FLoX sensor dataset for monitoring of high-Arctic tundra vegetation phenology and Sun-Induced Fluorescence (SIF)

A hyperspectral field sensor (FloX) was installed in Adventdalen (Svalbard, Norway) in 2019 as part of the Svalbard Integrated Arctic Earth Observing System (SIOS) for monitoring vegetation phenology and Sun-Induced Chlorophyll Fluorescence (SIF) of high-Arctic tundra. This northernmost hyperspectral sensor is located within the footprint of a tower for long-term eddy covariance flux measurements and is an integral part of an automatic environmental monitoring system on Svalbard (AsMovEn), which is also a part of SIOS. One of the measurements that this hyperspectral instrument can capture is SIF, which serves as a proxy of gross primary production (GPP) and carbon flux rates. This paper presents an overview of the data collection and processing, and the 4-year (2019–2021) datasets in processed format are available at: https://thredds.met.no/thredds/catalog/arcticdata/infranor/NINA-FLOX/raw/catalog.html associated with https://doi.org/10.21343/ZDM7-JD72 under a CC-BY-4.0 license. Results obtained from the first three years in operation showed interannual variation in SIF and other spectral vegetation indices including MERIS Terrestrial Chlorophyll Index (MTCI), EVI and NDVI. Synergistic uses of the measurements from this northernmost hyperspectral FLoX sensor, in conjunction with other monitoring systems, will advance our understanding of how tundra vegetation responds to changing climate and the resulting implications on carbon and energy balance. Chlorophyll fluorescenceSolar Induced Fluorescence (SIF)ReflectancePhotosynthetic functionMERIS terrestrial chlorophyll index (MTCI)High-Arctic tundrapublishedVersio

Assessment of the risk to Norwegian biodiversity from import and keeping of crustaceans in freshwater aquaria

Introduction The Norwegian Scientific Committee for Food and Environment (VKM) was requested by the Norwegian Environment Agency to assess the risk of negative impacts to biodiversity in Norway resulting from import of crustacean decapods for keeping in freshwater aquariums. VKM was asked to 1) list species of crayfish, crabs and shrimps that are currently kept in freshwater aquaria in Norway, and species that are likely to be kept in freshwater aquaria in Norway within the next 10 years, 2) assess the ability of the species to survive under Norwegian conditions and cause impacts on ecosystems and other species, and 3) state the potential negative effects on the biological diversity of diseases caused by pathogens, regulated under the Norwegian Food Act.Methods The risk assessment, without focus on pathogens, was performed in two steps. First, we used a pre-screening toolkit to identify species of crayfish, crabs and shrimps with potential to become invasive in freshwater habitats in Norway. Each species was given an invasiveness score based on 55 questions on biogeography, ecology, and climate change. In a second step, a full risk assessment, including the potential impacts of pathogens, was conducted on those species receiving the highest invasiveness score. This assessment included questions on the organism’s probability of entry and pathways of entry, establishment and spread, potential impacts on biodiversity, and how climate change scenarios might affect the assessment. Likelyhood and confidence was assessed for each question. In conclusion, each species was designated as either low-, moderate-, or high risk. Many crustacean decapod species are confirmed or suspected carriers of pathogens that can cause mass mortality among native crustaceans. The risk posed by crustaceans as carriers of pathogens may be independent of the environmental risk that they pose through ecological interactions. Therefore, the four crustacean disease pathogens that are regulated under the Norwegian Food Act, were assessed separately. These include Aphanomyces astaci causing crayfish plague, white spot syndrome virus (WSSV) causing white spot disease, Taura syndrome virus (TSV) causing Taura syndrome, and yellow head virus genotype 1 (YHV1) causing yellow head disease. The assessments comprised questions on the pathogen’s probability of entry (as a hitchhiker organism with imported crustaceans), pathways of entry, establishment and spread, and potential impact on crustacean biodiversity. Likelihood and confidence were assessed for each question. In conclusion, each pathogen was designated as either low-, moderate-, or high risk.In a third step, we categorized the likelihood that a crustacean species introduces a pathogen associated with a high- or moderate risk into: I) known chronic carriers, II) suspected chronic carriers, III) suspected situational carrier, IV) possible pathogen transmitters, and V) no direct or circumstantial evidence for carrier status or pathogen transmission in the genus.Results Based on information from the Norwegian Pet Trade Association, the project group listed 112 taxa (mainly species and some genera) of freshwater crayfish, crabs and shrimps that are relevant for trade in Norway. These included 38 crayfish taxa, 28 crab taxa, and 45 shrimp taxa. In addition, one marine crab was included. Sixteen species of crayfish, four species of shrimps, and two species of crabs underwent a full ecological risk assessment. The probabilities of entry both into the aquarium trade in Norway, and potentially further into Norwegian nature, were based on the prevalence of the species in the aquarium trade in Norway. We assumed that all species were equally likely to escape captivity or to be released. The four pathogens regulated under the Norwegian Food Act are either known or potential hazards to biodiversity in Norway. A. astaci is already present in Norway. It is regarded among the greatest threats to European freshwater crayfish, including noble crayfish (Astacus astacus). American freshwater crayfish are either known or suspected chronic carriers of A. astaci, while several crayfish species from other continents, as well as some species of crab and shrimp, may be situational carriers. WSSV is a "non-exotic" list 2 disease. All decapods can be infected by the virus. WSSV is primarily a problem in shrimp farming in Asia, but has spread to America and more recently to Australia. WSSV can cause 100% mortality in noble crayfish at water temperatures above 20 °C. Both TSV and YHV1 are "exotic" list 1 diseases. These can infect and cause high mortality in a limited range of saltwater shrimps. There is no evidence that TSV and YHV1 pose a risk to freshwater crayfish in the Nordic climate, nor is introduction likely through aquarium trade in freshwater crustaceans. Several other pathogens that cause crustacean dirsease are listed by the World Organization for Animal Health (OIE). These were briefly assessed, but not fully risk assessed.Conclusions VKM concluded that the risk of negative impacts on biodiversity caused by ecological interactions following import and private keeping of crayfish is high for Faxonius virilis, Faxonius spp., Procambarus clarkii, P. virginalis, and Pacifastacus leniusculus. These species can displace native crayfish, reduce the abundance of aquatic plants, and cause cascading effects that negatively influence invertebrates, fish, and birds. They can likely establish in Norwegian nature under the current climate conditions. The risk of negative consequences is moderate (with medium confidence) for the crayfish Cambarellus patzcuarensis, Procambarus alleni, Creaserinus fodiens, Cambarellus montezumae, Cherax monticola, Cherax tenuimanus, Faxonius neglectus. Perconon gibbesi of the crabs and Neocaridina davidi and Macrobrachium rosenbergii of the shrimps were associated with a moderate risk with medium confidence. Species associated with medium risk are omnivorous keystone species that will have at least moderate ecological impact on littoral freshwater ecosystems (medium confidence) if established in dense populations. None of the species associated with medium risk are likely to establish today. However, climate change will increase the risk for establishment and resulting ecological impact. The risk for negative impacts caused by the crayfish plague pathogen Aphanomyces astaci is high with high confidence. Crayfish plague can cause up to 100% mortality, and has already eradicated several noble crayfish populations in Norway. For WSSV, the risk for negative impact is moderate with high confidence. The risks associated with TSV and YHV1 are assessed as low for Norwegian crustacean biodiversity. According to the risk assessment of pathogens and the categorization of crustacean species based on their likelihood of being carriers of A. astaci and WSSV, 25 and 13 species of crayfish are associated with a high and medium risk, respectively. Four and 25 species of crabs are associated with a medium and low risk, respectively, and 14 and 31 species of shrimps are associated with medium and low risk, respectively. Notably, all species in the named genera should be regarded as belonging to the given risk category. OIE and general literature provide information of known crustacean diseases along with known susceptible crustacean hosts. However, there is a lack of information regarding carrier status of known and unknown disease pathogens for many exotic crustaceans. In this perspective, all exotic crustaceans should be regarded as potentially infected with a known or unknown pathogen. In order to reduce the risk of spreading diseases, eggs and living or dead animals should under no circumstances be disposed of in nature. The same applies for aquarium water or any material, such as gravel or ornamental plants, that have been in contact with the animals or water in the aquarium. The current permit requirement exemption for import of freshwater organisms that can only survive at temperatures above 5 °C provides no protection against the introduction, establishment, and spread of accompanying pathogens that could cause mass mortality in Norwegian crustacean populations. Finally, we can never predict how, or from which host species, a new disease might emerge. Many pandemics and plagues result from cross-continental pathogen-host jumps often facilitated by human transport, trade, introduction, release, or escape of alien species and associated alien pathogens

Assessment of the risk to Norwegian biodiversity from import and keeping of crustaceans in freshwater aquaria. Scientific Opinion of the Panel on Alien Organisms and trade in Endangered Species (CITES) of the Norwegian Scientific Committee for Food and Environment

Key words: Risk assessment, Crayfish, Shrimps, Crabs, Climate change, Aphanomyces astaci, White spot syndrome, Alien species, Biological invasion Introduction The Norwegian Scientific Committee for Food and Environment (VKM) was requested by the Norwegian Environment Agency to assess the risk of negative impacts to biodiversity in Norway resulting from import of crustacean decapods for keeping in freshwater aquariums. VKM was asked to 1) list species of crayfish, crabs and shrimps that are currently kept in freshwater aquaria in Norway, and species that are likely to be kept in freshwater aquaria in Norway within the next 10 years, 2) assess the ability of the species to survive under Norwegian conditions and cause impacts on ecosystems and other species, and 3) state the potential negative effects on the biological diversity of diseases caused by pathogens, regulated under the Norwegian Food Act. Methods The risk assessment, without focus on pathogens, was performed in two steps. First, we used a pre-screening toolkit to identify species of crayfish, crabs and shrimps with potential to become invasive in freshwater habitats in Norway. Each species was given an invasiveness score based on 55 questions on biogeography, ecology, and climate change. In a second step, a full risk assessment, including the potential impacts of pathogens, was conducted on those species receiving the highest invasiveness score. This assessment included questions on the organism’s probability of entry and pathways of entry, establishment and spread, potential impacts on biodiversity, and how climate change scenarios might affect the assessment. Likelyhood and confidence was assessed for each question. In conclusion, each species was designated as either low-, moderate-, or high risk. Many crustacean decapod species are confirmed or suspected carriers of pathogens that can cause mass mortality among native crustaceans. The risk posed by crustaceans as carriers of pathogens may be independent of the environmental risk that they pose through ecological interactions. Therefore, the four crustacean disease pathogens that are regulated under the Norwegian Food Act, were assessed separately. These include Aphanomyces astaci causing crayfish plague, white spot syndrome virus (WSSV) causing white spot disease, Taura syndrome virus (TSV) causing Taura syndrome, and yellow head virus genotype 1 (YHV1) causing yellow head disease. The assessments comprised questions on the pathogen’s probability of entry (as a hitchhiker organism with imported crustaceans), pathways of entry, establishment and spread, and potential impact on crustacean biodiversity. Likelihood and confidence were assessed for each question. In conclusion, each pathogen was designated as either low-, moderate-, or high risk. In a third step, we categorized the likelihood that a crustacean species introduces a pathogen associated with a high- or moderate risk into: I) known chronic carriers, II) suspected chronic carriers, III) suspected situational carrier, IV) possible pathogen transmitters, and V) no direct or circumstantial evidence for carrier status or pathogen transmission in the genus. Results Based on information from the Norwegian Pet Trade Association, the project group listed 112 taxa (mainly species and some genera) of freshwater crayfish, crabs and shrimps that are relevant for trade in Norway. These included 38 crayfish taxa, 28 crab taxa, and 45 shrimp taxa. In addition, one marine crab was included. Sixteen species of crayfish, four species of shrimps, and two species of crabs underwent a full ecological risk assessment. The probabilities of entry both into the aquarium trade in Norway, and potentially further into Norwegian nature, were based on the prevalence of the species in the aquarium trade in Norway. We assumed that all species were equally likely to escape captivity or to be .........publishedVersionpublishedVersio

Image quality of list-mode proton imaging without front trackers

List mode proton imaging relies on accurate reconstruction of the proton most likely path (MLP) through the patient. This typically requires two sets of position sensitive detector systems, one upstream (front) and one downstream (rear) of the patient. However, for a clinical implementation it can be preferable to omit the front trackers (single-sided proton imaging). For such a system, the MLP can be computed from information available through the beam delivery system and the remaining rear tracker set. In this work, we use Monte Carlo simulations to compare a conventional double-sided (using both front and rear detector systems) with a single-sided system (only rear detector system) by evaluating the spatial resolution of proton radiographs (pRad) and proton CT images (pCT) acquired with these set-ups. Both the pencil beam spot size, as well as the spacing between spots was also adjusted to identify the impact of these beam parameters on the image quality. Relying only on the pencil beam central position for computing the MLP resulted in severe image artifacts both in pRad and pCT. Using the recently extended-MLP formalism that incorporate pencil beam uncertainty removed these image artifacts. However, using a more focused pencil beam with this algorithm induced image artifacts when the spot spacing was the same as the beam spot size. The spatial resolution tested with a sharp edge gradient technique was reduced by 40% for single-sided (MTF10% = 3.0 lp/cm) compared to double-sided (MTF10% = 4.9 lp/cm) pRad with ideal tracking detectors. Using realistic trackers the difference decreased to 30%, with MTF10% of 4.0 lp/cm for the realistic double-sided and 2.7 lp/cm for the realistic single-sided setup. When studying an anthropomorphic paediatric head phantom both single- and double-sided set-ups performed similarly where the difference in water equivalent thickness (WET) between the two set-ups were less than 0.01 mm in homogeneous areas of the head. Larger discrepancies between the two set-ups were visible in high density gradients like the facial structures. A complete CT reconstruction of a Catphan$^{\circledR}$ module was performed. Assuming ideal detectors, the obtained spatial resolution was 5.1 lp/cm for double-sided and 3.8 lp/cm for the single-sided setup. Double- and single-sided pRad with realistic tracker properties returned a spatial resolution of 3.8 lp/cm and 3.2 lp/cm, respectively. Future studies should investigate the development of dedicated reconstruction algorithms targeted for single-sided particle imaging.publishedVersio

Uncertainty-aware spot rejection rate as quality metric for proton therapy using a digital tracking calorimeter

Objective. Proton therapy is highly sensitive to range uncertainties due to the nature of the dose deposition of charged particles. To ensure treatment quality, range verification methods can be used to verify that the individual spots in a pencil beam scanning treatment fraction match the treatment plan. This study introduces a novel metric for proton therapy quality control based on uncertainties in range verification of individual spots. Approach. We employ uncertainty-aware deep neural networks to predict the Bragg peak depth in an anthropomorphic phantom based on secondary charged particle detection in a silicon pixel telescope designed for proton computed tomography. The subsequently predicted Bragg peak positions, along with their uncertainties, are compared to the treatment plan, rejecting spots which are predicted to be outside the 95% confidence interval. The such-produced spot rejection rate presents a metric for the quality of the treatment fraction. Main results. The introduced spot rejection rate metric is shown to be well-defined for range predictors with well-calibrated uncertainties. Using this method, treatment errors in the form of lateral shifts can be detected down to 1 mm after around 1400 treated spots with spot intensities of 1 × 107 protons. The range verification model used in this metric predicts the Bragg peak depth to a mean absolute error of 1.107 ± 0.015 mm. Significance. Uncertainty-aware machine learning has potential applications in proton therapy quality control. This work presents the foundation for future developments in this area.publishedVersio

Stepperøyrkvein Calamagrostis purpurascens i Wijdefjorden på Svalbard - einaste lokalitetar i Europa

Source: pdf of printed version. Blyttia 74(4), 2016. Norsk Botanisk Forening</a