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Vertebral deformities in cultured big size Rainbow Trout: Radiological analysis from juvenile to harvest size
Full text linkVertebral deformities are a big challenge in Rainbow Trout seawater aquaculture. However, supportive scientific literature is missing. The present study used radiology to follow the development of vertebral deformities in a population of farmed Rainbow Trout as they grew from 36 g to 5.5 kg. In addition, separately collected deformity screening data from three other farmed populations were included for comparison.
The fish developed deformities in different vertebral regions over time, eventuating to affect almost the entire vertebral column. At this point, the fish were ∼ 5.5 kg and 93 % of the fish had one or more deformed vertebrae. A negative relationship between severity of deformity (number of deformed vertebrae per individual), and fish length and weight strongly suggest a negative impact on fish welfare. The most frequently affected area was the ural region of the vertebral column. This region is a part of the caudal fin complex which also suffered from degradation of the fin rays. Ural region deformities were also frequent in the separately investigated populations.
The current results indicate that Rainbow Trout are not able to maintain normal bone development under current farming conditions, consequently, jeopardizing the welfare of the fish.publishedVersio
New update of a fortification model
Full text linkVKM has calculated the intakes of vitamins and minerals and compared them with the tolerable upper intake levels (UL) in a model for assessing the fortification of food and drink. Fortification means adding vitamins and minerals. The intake calculations cover all age groups. The model has been updated with data from a new dietary survey for adults, and with new tolerable upper intake levels from EFSA for several of the vitamins and minerals. Some of the data entered into the model has been taken from Danish dietary surveys, as there is no Norwegian data available. For most nutrients, it is the amount that can be added for 1- and 2-year-olds that regulates the fortification. The model was established in 2006, and has been updated in 2009, 2013 and 2021. The model does not include the risk of low intake of nutrients. The work has been commissioned by the Norwegian Food Safety Authority, which will use the results from the model as part of the basis for assessing applications for food fortification.New update of a fortification modelpublishedVersio
Integrating and assessing machine learning acoustic target classification models for fish survey estimations
Full text linkScientific acoustic-trawl surveys collect data that are used to track fish and zooplankton populations over time. Most rely on manual annotation during acoustic target classification, but automated methods have been proposed. Here, we report on a framework for testing deep learning-based acoustic classification models and integrating them into the survey estimation process. The approach was applied to North Sea lesser sandeel (Ammodytes marinus) surveys from 2009 to 2024. Three U-Net-based models were tested: a baseline model, a depth-aware model, and a model trained with similarity-based sampling for the foreground class. A threshold based on the training years was applied to the models’ SoftMax outputs. The official sandeel estimation process was used as a starting point, replacing input data with model predictions. The biomass estimates were generally similar between manual annotations and model-based estimates, but variation existed across years. The baseline model misclassified a surface layer as sandeel and was prone to bottom contamination, causing larger deviations from official estimates. Discrepancies between the similarity-based model and the official estimates resulted from an incorrectly applied SoftMax threshold, leading to missing school interiors and indicating threshold sensitivity. Unlike traditional F1 score evaluations commonly used in image-based classification, our comparison assessed predictions in a survey-relevant context. The evaluation indicated that full automation was not yet feasible, but the predictions could be used as starting points for manual scrutiny. Annotating a subset of the data to refine thresholds or employing more advanced active learning approaches could enhance efficiency. These methods could enable faster, more consistent survey annotation.publishedVersio
Exploring multistability in marine ecosystems: Insights from food web model dynamics
No full textThis review synthesizes the role of multistability in deterministic food web models of marine ecosystems, focusing on how structural features of ordinary differential equation (ODE) models give rise to multiple stable states. From an initial pool of 178 publications, we systematically selected 35 studies that explicitly report multistability in predator–prey and food web models. These were analyzed according to key structural components – such as functional responses, growth and mortality terms, nonlinearities, and network topologies – to identify the mechanisms underpinning the emergence of bistability, tristability, and higher-order multistability.
The reviewed models exhibit a wide range of attractor types, including equilibrium points, limit cycles, and chaotic attractors. Our analysis highlights the influence of non-monotonic functional responses, intraspecific competition, Allee effects, and time-scale separation in generating complex dynamics. Furthermore, we find that bifurcation analysis and numerical simulations are the primary tools used to characterize stability landscapes and attractor transitions.
Despite the advances in modeling techniques, the review reveals a significant gap between theory and empirical application. Most models are general in nature and seldom incorporate real-world species, parameterized data, or specific ecosystem structures. We discuss this gap and propose a collaborative modeling approach focused on keystone species and the development of a shared repository of food web models.
By categorizing multistable behaviors and clarifying their mechanistic origins, this review contributes towards a more robust theoretical foundation for understanding multistability in marine ecosystems.publishedVersio
Invading and range-expanding pink salmon inform management actions for marine species on the move
Full text linkSpecies redistributions, whether resulting from invasions or range expansions, pose similar challenges for conservation and man- agement. Redistribution impacts on host ecosystems and species combine with those from climate c hange, whic h are already acute at northern latitudes. Using pink salmon Oncorhync hus gorbusc ha , whic h are native to the Pacific Ocean, we employ knowledge exchange to inform decision-making in non-native marine areas: they are expanding their range to the Arctic Ocean and are invasive in the At- lantic Ocean. The predicted future marine distribution of pink salmon focuses ef for t on where and when pink salmon are present and informs on potential interactions with native species. Management actions taken in the Atlantic Ocean to reduce invasive pink salmon are resource-intensive, but removed salmon could be a food resource. Addressing identified gaps regarding the invasion potential of pink salmon, interactions among pink salmon and other species, and current mitigation efforts would support forward-thinking man- agement decisions given predictions of continued environmental change. We also highlight steps that can be taken immediately to coordinate actions and better inform responses. Managed for production in the Pacific and as an invasion in the Atlantic, pink salmon provide a tangible approach to informed decision-making through collaboration for marine species on the move. range-expanding; management; Arctic; Atlantic; pink salmon; climate change; distribution shift; invasive speciespublishedVersio
Analysis of microplastics in selected North Sea areas and the Skagerrak - Mareano studies 2023
No full textPlastforsøpling (makro-, meso-, mikro- og potensielt nanoplast) er anerkjent som et globalt problem de siste årene. Mikroplast er funnet i alle undersøkte deler av marint miljø og i et stort antall dyre- og plantearter. På verdensbasis øker produksjonen av plast fortsatt, mens avfallhåndteringen i store deler av verden fortsatt er utilstrekkelig utviklet, og det forventes følgelig å gi en økende plastforsøpling i årene som kommer. Marine sedimenter ansees som et endepunkt i mikroplastens reise gjennom økosystemet. Her akkumulerer mikroplast partikler av mange forskjellige polymer-(plast)typer, selv de som på grunn av sin lavere tetthet enn sjøvann burde flyte på havoverflaten. I 2023 har Mareano-prosjektet valgt ut 8 overflatesedimentprøver fra Utsira-området (3 lokaliteter), Sørlige Nordsjø (NSJ-1; 1 lokalitet) og Skagerrak (4 lokaliteter) og i tillegg 3 sedimentkjerner fra Utsira-området (1 lokalitet) og Skagerrak (2 lokaliteter) til mikroplastanalyse. Havforskningsinstituttet (HI) har på oppdrag fra Mareano-prosjektet utført analysene. Sedimentprøvene (100 – 200 g våtvekt) ble homogenisert, og dernest ble en tetthetsseparasjon gjennomført i spesialkonstruerte «bauta» i en konsentrert saltløsning (sinkklorid (ZnCl2)/kalsiumklorid (CaCl2), ρ ~1,5 g/cm3). Prøvene ble deretter filtrert over en 45 µm stålfilter. Filteret ble brettet til en konvolutt for å sikre partiklene og beskytte prøven mot kontaminering. Deretter fulgte kjemiske behandlinger for å fjerne/redusere biologisk materiale som tre og skjellfragmenter. Etter overføring til et analysefilter (PTFE, 3,0 µm porestørrelse) og tørking, ble prøvematerialet analysert på antall, størrelse og type av mikroplastpartikler ved hjelp av infrarød-mikroskopisk bildegiving (µIR). Prøvematerialet ble videre overført til et glassfiberfilter (GF/C 1,2 µm porestørrelse), tørket og analysert på vektinnhold av forskjellige mikroplast typer ved hjelp av pyrolyse-gass-kromatografi-massespektrometri (Py-GC-MS). Mikroplastkonsentrasjonene i overflatesedimentprøvene analysert i dette prosjektet inneholder mellom 96 og 809 (378±130) mikroplast partikler per kg tørrvekt (MP/kg tv.), basert på µIR-spektroskopi. Basert på Py-GC-MS ligger plastforurensningsnivåer i overflatesedimentprøvene mellom 167 og 405 (274±75) µg per kilogram tørrvekt (µg/kg tv.). I kjernen fra stasjon R3200 ble det funnet mellom 175 og 476 (316±86) MP/kg tv., basert på µIR-spektroskopi. Analysen med Py-GC-MS fant konsentrasjoner mellom 77 og 412 (233±107) µg/kg tv. Mellom 145 og 1126 (491±175) MP/kg tv. ble detektert i kjerne R3310 ved hjelp av µIR-spektroskopi. Mikroplast konsentrasjonene ifølge Py-GC-MS ligger mellom 75 og 315 (138±54) µg/kg tv. Enda flere MP partikler ble detektert i kjerne R3365 med 249 til 1808 (812±287) MP partikler per kg tørrvekt. Ifølge Py-GC-MS ligger mikroplast konsentrasjonene mellom 113 og 473 (262±70) µg/kg tv. Den dominerende plasttypen er polyetylen (PE), både i µIR-analysen og i Py-GC-MS.Analyse av mikroplast i sedimenter fra deler av Nordsjøen og Skagerrak — Mareano-undersøkelser i 2023Analysis of microplastics in selected North Sea areas and the Skagerrak - Mareano studies 2023publishedVersio
Diet and feeding strategies of myctophids in the Northeast Atlantic
No full textThe trophic ecology of myctophids was investigated during spring 2019 in a large geographical span in the Northeast Atlantic (from Cape Verde to North of France), covering oligotrophic open ocean waters off south Iberia to the productive coastal areas of western Morocco. A total of 417 stomachs from 22 different myctophid species were analyzed. Myctophids from the southern areas (from 20 to 42° N) mostly fed on copepods, whereas amphipods were the main prey of myctophids collected in the northern stations (from 42 to 48° N). The calanoids Pleuromamma spp. and Candacia spp., amphipods, euphausiids, and decapod larvae were the most positively selected prey by all myctophid species, whenever these prey were present. Pleuromamma spp. was the most important prey for most species, with the largest average contribution to dietary carbon (49.6 ± 21.1%), while Candacia spp. was the dominant prey of Lampanyctus ater (contributing to 40.3% of the estimated dietary carbon), and amphipods were the dominant prey for Hygophum benoiti (39.0%), Myctophum punctatum (58.4%) and Symbolophorus veranyi (56.0%). Results of the present study indicate that myctophids in the Northeast Atlantic are mainly characterized by specialized feeding strategies, although some species showed mixed strategies (Ceratoscopelus warmingii, Lepidophanes gaussi, Lobianchia dofleini and Lobianchia gemellarii) and few species (Hygophum hygomii, H. benoiti and S. veranyi) generalized feeding strategy. Our data provide key knowledge for food web and ecosystem studies and contribute to determining the trophodynamics of the global mesopelagic fish community.acceptedVersio
Forsøk med seleksjonspresenninger i kvadratmaskesekk i snurrevadfiske etter hyse
Full text linkDe siste årene har Norges totale tillatte fangst av nordøstarktisk hyse vært 90 000–100 000 tonn, hvorav nesten halvparten er fangstet av kystflåten. Snurrevad har møtt utfordringer på grunn av betydelig fangst av undermålshyse, noe som har ført til hyppige områdestenginger. Denne studien evaluerer modifikasjoner av snurrevadredskap for å forbedre størrelsesselektiviteten og redusere fangst av undermålsfisk. Tidligere forbedringer, som firkantmaskede snurrevadsekker som ble påbudt i 2002, har vist forbedret størrelsesselektivitet. Problemene vedvarer imidlertid på grunn av lange sekkeforlengelser av diamantseksjoner og uønsket overflateseleksjon, noe som reduserer overlevelsesraten for undermålsfisk. Denne studien undersøker effekten av å implementere seleksjonspaneler (SP), inspirert av "Excluder"-enheten som brukes i industrielt trålfiske etter øyepål og tobis, i firkantmaskede seksjoner. Forsøk ble utført ombord på MS Båragutt i mai 2023 og sammenlignet standardkonfigurasjoner med eksperimentelle design som inkluderer SP-er. SP besto av en 30x30 cm presenningsfirkant beregnet på å stimulere fiskens adferd for økt seleksjon på fiskedyp. Resultatene viste at SP-er økte rømningsraten signifikant for undermålshyse (<40 cm). Konfigurasjoner med SP-er forårsaket imidlertid også tap for fisk mellom 40–50 cm. Studien konkluderer med at SP-er forbedrer størrelsesselektiviteten, men det er behov for optimalisering for å balansere fangst av undermålsfisk og tap av fisk over minstemål. Fremtidig forskningForsøk med seleksjonspresenninger i kvadratmaskesekk i snurrevadfiske etter hysepublishedVersio
Cold Seeps and Coral Reefs in Northern Norway: Carbon Cycling in Marine Ecosystems With Coexisting Features
Full text linkCold seeps and cold-water corals (CWCs) coexist on Northern Norway's continental shelf at the Hola trough between Lofoten and Vesterålen. Here, cold seeps release methane from the seabed, yet none reaches the sea surface. Instead, the methane dissolves and disperses in the ocean where it is ultimately consumed by methane-oxidizing microorganisms. These microorganisms metabolize methane and release carbon dioxide and dissolved organic matter (DOM), which may impact the biogeochemical habitat of CWCs in close vicinity of cold seeps. We investigated the biogeochemistry of carbon, carbon isotopes, nutrients, DOM compositions, and microbial diversity in the water column. Our results indicated that dissolved inorganic carbon concentrations were 29% higher near cold seeps with modified carbon's isotopic compositions. The hydrophysical parameters and surface-to-bottom control of sinking particles mainly govern water column productivity and nutrient cycle. DOM compositions implied that the seep-associated microbiomes modify DOM's chemical diversity and isotopic composition at CWCs and the entire water column near cold seeps. Cold seeps and CWCs coexist in Northern Norway's continental shelves; however, enhanced water temperatures and consequent increase in methane release at cold seeps may modify the carbon cycling in the area, which could mitigate the ecological role and functioning of CWC reefs in the future.publishedVersio
Changes in Planktic Foraminiferal Distribution, Productivity, and Preservation in the Barents Sea During the Last Three Millennia
Full text linkPlanktic foraminifers are ubiquitous marine calcifiers sensitive to ocean biogeochemical and physical changes. Their fossil remains have thus been widely used for the reconstruction of past oceanographic and climatic changes. Here, we have investigated the distribution patterns of planktic foraminiferal species, their abundance, shell size, and preservation state in two sediment cores from the northern and southern Barents Sea during the last three millennia and compared them with a living assemblage from the water column. The study area covers the cold Arctic zone in the north and the warm boreal zone in the south. In the north, we found very low to almost zero abundances of fossil planktic foraminifers, mainly since c. 1300 Common Era (C.E.), and dominance by the polar species Neogloboquadrina pachyderma. In the south, higher abundances were found, where the taxa was dominated by the subpolar species Turborotalita quinqueloba, Globigerinita uvula and Neogloboquadrina incompta. The highest foraminiferal concentrations occurred in the transition phases between cold and warm periods, with a rapid decrease in abundance during the last two hundred years coinciding with the Industrial Revolution. The lack of planktic foraminifers since c. 1300 C.E. in the north and the consistently low %CaCO3 are attributed to CaCO3 dissolution in the sediment, possibly driven by the decomposition of total organic matter as suggested by high %TOC, high surface productivity, and the presence of solely agglutinated benthic foraminifers. Dissolution of CaCO3 muted the signals of paleoproductivity and paleoclimate in the north, while the southern site showed clear variability throughout the investigated time intervalChanges in Planktic Foraminiferal Distribution, Productivity, and Preservation in the Barents Sea During the Last Three MillenniaacceptedVersio