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Videreutviklet protokoll for vurdering av modningsgrad hos oppdrettstorsk
Get PDFDen videreutviklede protokollen for vurdering av modningsnivået hos oppdrettstorsk skisserer distinkte modningsstadier hos både hann- og hunntorsk (Gadus morhua). Denne protokollen hjelper til med å evaluere graden av modenhet hos torsk i oppdrettsanlegg. Hvert stadium involverer en makroskopisk vurdering, som inkluderer bilder av gonadene både inne i og utenfor fisken, detaljerte bilder, en generell beskrivelse av gonadene og fiskemålinger. I tillegg omfatter den en mikroskopisk vurdering med histologiske bilder og beskrivelser. Protokollen gir også retningslinjer for korrekt innsamling av gonadeprøver fra hann- og hunntorsk for videre histologiske analyser, samt instruksjoner for å ta bilder som muliggjør visuell vurdering av modningsstadier av en tredjepart. Til slutt presenteres resultater fra første år overvåkning av modningsgrad i vinter 2023-2024 i fire torskeoppdrettsvirksomheter i Norge, med en sammenligning mellom vurderinger gjort av næringsaktører og Havforskningsinstituttet.Videreutviklet protokoll for vurdering av modningsgrad hos oppdrettstorskpublishedVersio
Salmon farming alters the structure and functioning of Norwegian maerl bed communities
Get PDFEffluents resulting from fish farming activities can alter the structure and functioning of benthic ecosystems. In Norway, recent technological advances within the salmon industry have facilitated the expansion of aquaculture into shallower locations, leading to additional pressures upon coastal habitats. Maerl/rhodolith beds are important bioengineers in coastal waters—supporting highly diverse associated macrofaunal communities—and are likely to be particularly at risk. This study aims to investigate the environmental changes induced by fish farms in their vicinity and their impact on the structure and functioning of maerl bed macrofaunal communities. High dissolved nutrients and organic enrichment levels were observed close to the cages, associated with lower live maerl cover. Overall, the most substantial impact of salmon farms on macrofaunal communities was observed within 100 m from the cages. Nevertheless, changes in the structure and functioning of assemblages were evidenced up to 300 m. In the vicinity of the cages, communities were characterized by the dominance of endobenthic subsurface deposit feeders and opportunistic species, notably the polychaetes Chaetozone sp., Capitella sp. and Scoloplos armiger. Conversely, sites situated farther away from the cages exhibited higher abundances of epibenthic taxa, including crawlers, grazers and species sensitive to organic enrichment. Sites unaffected by the presence of fish farms were described by high abundances of the ophiuroid Ophiura robusta, the polychaete Proclea graffi and ostracods, reflecting more favourable environmental conditions. Such changes in macrofaunal communities highlight the vulnerability of maerl beds to the impacts of aquaculture, thus emphasizing the importance of rigorous site selection when establishing new fish farming facilities.publishedVersio
Ocean warming shapes embryonic developmental prospects of the next generation in Atlantic cod
Get PDFAlthough early embryonic protein production relies exclusively on maternal molecules such as messenger RNAs (mRNAs) incorporated into ovarian follicles, knowledge about any thermally induced, intergenerational effects is scarce in ectotherms. Here, we investigated how elevated temperatures (9°–12°C vs. 6°C) during oogenesis influenced the next generation by targeting maternal mRNAs in Atlantic cod (Gadus morhua) embryos, in view of up- and down-regulated genes in ovarian follicles of pre-spawning adults. Overall, the spawning female liver showed significantly higher levels of free amino acids and N-metabolites at 9°C than at 6°C. Higher-than-optimal temperatures induced adjustments in embryo transcriptome proportional to the temperature increase relative to the control group. The adjustments included alterations in maternal-effect genes, which are developmentally conserved among vertebrates. The transcriptomic differences for a selection of genes in embryos were reflected in ovarian follicles (containing multiple cell types) several months ahead of the spawning season, implying that environmental conditions of the adults are key for adjusting the genetic instructions for offspring development. This programming of fundamental traits from mother to offspring appears part of a sophisticated process to adapt the offspring to a changing ocean, though within life stage-specific, physiological thermal tolerance windows.publishedVersio
A holo-omics analysis shows how sugar kelp can boost gut health in Atlantic salmon
Get PDFThe projected growth of Aquaculture requires continuous optimisation of feeding regimes, especially in enhancing disease resilience through immunostimulating feed supplements. Seaweed has been introduced as a promising supplement due to its proposed immunostimulant effects, while mitigating carbon emissions and marine eutrophication. Two separate growth trials were performed to evaluate the effects of a seaweed supplement, focusing on a closed land-based RAS system with fish growing from ~300–600 g and an open water netbased trial with fish growing from ~500–2500 g. A multi-omics approach was taken to investigate the effect of using up to 2 % fermented sugar kelp (Saccharina latissima) as a supplement on the growth performance and gut health of Atlantic salmon (Salmo salar L.). Standard growth metrics and quality indicators were coupled with multi-omics data for the host intestinal transcriptome, intestinal metabolome, and intestinal microbiome. Levels of iodine and heavy metals in the fish fillets resulting from seaweed inclusion were evaluated. Seaweed additives up to 2 % had no negative impact on the salmon growth performance or other health parameters. While concentration of iodine increased with seaweed addition, all levels remain below recommended thresholds. Furthermore, gut transcriptome analyses of 179 individuals revealed multiple indications for an immunostimulant effect of seaweed, including overexpression of the mucin biosynthesis and pyrimidine metabolism pathways related to mucus production and intestinal homeostasis. Genome-resolved metagenomics revealed a core microbiome dominated by Mycoplasma, Photobacterium, and Brevinema species. Interestingly, the assembled genomes of these three core species had consistently higher levels of genome erosion and gene loss compared to other present species suggesting host adaptation. Further, reduced prevalence of known pathogens such as Aliivibrio highlights a potential protective effect of seaweed by impeding growth of opportunistic pathogens. Results suggest that supplementation of up to 2 % fermented seaweed can increase feed efficiency, stabilise the intestinal microbiome and potentially increase resistance against known pathogenic bacteria including Aliivibrio species. Seaweed Aquaculture Atlantic salmon Host-microbe interactions Multi-omics ImmunostimulantspublishedVersionacceptedVersio
Intercorrelations of Chlorinated Paraffins, Dechloranes, and Legacy Persistent Organic Pollutants in 10 Species of Marine Mammals from Norway, in Light of Dietary Niche
Get PDFShort-, medium-, and long-chain chlorinated paraffins (CPs) (SCCPs, MCCPs, and LCCPs) and dechloranes are chemicals of emerging concern; however, little is known of their bioaccumulative potential compared to legacy contaminants in marine mammals. Here, we analyzed SCCPs, MCCPs, LCCPs, 7 dechloranes, 4 emerging brominated flame retardants, and 64 legacy contaminants, including polychlorinated biphenyls (PCBs), in the blubber of 46 individual marine mammals, representing 10 species, from Norway. Dietary niche was modeled based on stable isotopes of nitrogen and carbon in the skin/muscle to assess the contaminant accumulation in relation to diet. SCCPs and dechlorane-602 were strongly positively correlated with legacy contaminants and highest in killer (Orcinus orca) and sperm (Physeter macrocephalus) whales (median SCCPs: 160 ng/g lw; 230 ng/g lw and median dechlorane-602: 3.8 ng/g lw; 2.0 ng/g lw, respectively). In contrast, MCCPs and LCCPs were only weakly correlated to recalcitrant legacy contaminants and were highest in common minke whales (Balaenoptera acutorostrata; median MCCPs: 480 ng/g lw and LCCPs: 240 ng/g lw). The total contaminant load in all species was dominated by PCBs and legacy chlorinated pesticides (63–98%), and MCCPs dominated the total CP load (42–68%, except 11% in the long-finned pilot whale Globicephala melas). Surprisingly, we found no relation between contaminant concentrations and dietary niche, suggesting that other large species differences may be masking effects of diet such as lifespan or biotransformation and elimination capacities. CP and dechlorane concentrations were higher than in other marine mammals from the (sub)Arctic, and they were present in a killer whale neonate, indicating bioaccumulative properties and a potential for maternal transfer in these predominantly unregulated chemicals.Intercorrelations of Chlorinated Paraffins, Dechloranes, and Legacy Persistent Organic Pollutants in 10 Species of Marine Mammals from Norway, in Light of Dietary NichepublishedVersionpublishedVersio
Onset of circadian rhythmicity in the brain of Atlantic salmon is linked to exogenous feeding
Get PDFAn organism’s biological processes are adapted to and driven by rhythmicity in the natural environment and periodicity of light is one of the most influential factors. In a developing organism, the onset of circadian rhythmicity might indicate the time point of functional necessity for aligning processes to the environment. Here, the circadian clock mechanism has been studied in the developing brain of Atlantic salmon (Salmo salar), by comparing the endogenous feeding alevin, independent on the environment for nutritional supply, to the exogenous feeding fry, dependent on the light period for detecting and catching prey. The results showed that while only a few clock genes were cyclic in the yolk sac alevins, many of the clock genes and genes of the circadian rhythm pathway cycled significantly in the feeding fry. Few genes were differentially expressed between time points in the circadian sampling series during the yolk sac stage, but several hundred genes were found differentially expressed in the first feeding stage. Genes important for cell cycle progression were cyclic or differentially expressed between time points after exogenous feeding, indicating a clock-controlled cell cycle at this stage. The expression of important genes in the melatonin synthesis were also cyclic in the feeding fry with an acrophase in the transition between light and dark or in darkness. Analyzing the impact of exogenous feeding on the developing brain supported a shift from utilization of proteins and lipids in the yolk to utilization and allocation of dietary energy and nutrients. Taken together, the life history transition related to onset of exogenous feeding is linked to the establishment of a persistent circadian rhythmicity in the salmon brain, which needs to be synchronized to light-dark cycles to enable the fry to search and capture feed.publishedVersio
The International Union for Conservation of Nature Red List does not account for intraspecific diversity
Get PDFThe International Union for Conservation of Nature (IUCN) Red List identifies threatened and endangered species and is a key instrument in global biodiversity conservation efforts. Our understanding of the structure and value of genetic biodiversity below the species level is rapidly increasing. Nonetheless, the IUCN assessment criteria overlook genetic variation within species. Here, we address this blind spot and discuss the principles of species conservation status classification relative to intraspecific biodiversity. We focus on coastal species, which thrive in heterogeneous environments known to drive genetic differentiation. The focal example species, Atlantic cod and sugar kelp, have contrasting life histories, are ecologically and economically important constituents of the coastal ecosystem, and are currently not classified as threatened in Norway and Canada. We expose important variation in population structure, the presence of ecotypes and genetic-environment covariation, as well as loss of ecotypes that threatens the conservation of these species. Because the genetic makeup of species directly influences their resilience, omitting this information from conservation status assessments can result in loss of adaptive capacity to future stressors, such as climate change. Consequently, recognizing and preserving intraspecific variation emerges as vital for species’ abilities to adapt to and survive in future ocean conditions.publishedVersio
Exploring ecosystem effects of underwater noise in the nordic seas, using the NoBa-Atlantis E2E model
Get PDFUnderwater noise generated by human activities, such as shipping and seismic surveys, has emerged as a growing concern. Despite the mounting evidence that noise negatively impacts marine mammals, fish, and invertebrates, end-to-end ecosystem models often overlook noise as a stressor. This omission is due to the complexity of studying noise’s influence on entire populations and ecosystems, making it difficult to gauge the potential total effects accurately. In this study, we implemented potential effects of underwater noise in the Atlantis ecosystem modeling framework. Noise effects on organisms were simulated through reduced growth and consumption rates, increased mortality and movement away from noisy areas. The noise module was tested by a Morris sensitivity analysis on most of the fish, mammal and invertebrate species in the model. The species were aggregated into 12 groups perturbed with six different noise levels, with the spatial dimension taken into account by repeating the analysis under varying spatial configurations. The results revealed substantial systemic effects from increased vulnerability to noise from zooplankton, while marine mammal noise vulnerability had relatively little impact, in line with earlier Atlantis studies. Additionally, the coastal area exhibited significantly higher biomass variability, indicating a need for more research in this region where noise is expected to increase the most. These results provide an initial estimation of the potential effects of noise at the ecosystem level in the Nordic and Barents Seas. However, for improved realism of the noise module in future studies, we emphasize the need to develop response functions for each species’ sensitivity to noise. Understanding such species-specific sensitivities will be crucial in devising effective strategies to mitigate the detrimental consequences of underwater noise on marine ecosystems.acceptedVersionpublishedVersio
Tackling the elephant in the room – Large-scale salmon farming and the potential for far-field ecosystem effects
Get PDFSignificant expansion in salmon production globally has been partially enabled through the establishment of large-capacity sea-farms in high-energy environments that collectively produce substantial quantities of organic waste with potential to cause regional scale environmental degradation. We analyse results from comprehensive spatial and temporal surveys of water column particulates and seabed environmental indicators for responses to farm production, and residual effects. Results confirmed that while the particles can and do reach a relatively wide area, benthic effects do not necessarily follow suit. There was limited evidence of longer-term environmental degradation at some near-field locations and spatially removed deeper sites. We concluded that evidence for regional biological effects was negligible, suggesting: i) modern waste tracing techniques are more sensitive than traditional effects indicators, and ii) waste fluxes in the far-field were being assimilated without causing environmental perturbation. Monitoring at potential accumulation points, especially for sites with complex bathymetry and hydrodynamics is advised.publishedVersio
Tag attachment innovation on spurdog (Squalus acanthias) reveals year-round coastal association of pregnant females in northeastern Atlantic waters
Get PDFThe spurdog (Squalus acanthias Linnaeus, 1758) is a globally distributed squaliform shark that has historically been overfished but is now recovering in the northeast Atlantic. Data series on spurdog movement and habitat use have been somewhat limited to research surveys due to challenges associated with electronic tagging. Here, we offer a revised attachment method for externally attached pop-up satellite archival tags that was successful in long-term deployments on pregnant females. Twenty-one spurdogs were tagged in two fjord systems in western Norway for an average of 243 days and provided new details about their behaviour, demonstrating affinity for coastal habitat based on the pop-up locations and recovery positions of the tags (84% within 40 km from tagging location), and depth–temperature profiles. It is likely that parturition therefore occurs in these coastal waters, making them important to the life cycle of this species. The realized depth niche of tagged individuals suggested that surveys may miss sharks if they do not cover the full water column because the sharks used large parts of the water column and spent much time in shallower waters, albeit with seasonal variations (deeper and shallower in winter and summer, respectively). Adoption of this tagging method and combination with movement data from acoustic transmitters will help to better resolve the behaviour of this species as it transitions from a species at risk to a managed fishery. Such studies will provide a more comprehensive understanding of the species' habitat requirements that will empower better informed protections against a return to the red list of threatened species.publishedVersio