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Transfer and bioaccumulation of chemical and biological contaminants in the marine polychaete Hediste diversicolor (OF müller 1776) when reared on salmon aquaculture sludge
Get PDFSide streams from aquaculture production such as fish sludge poses ample opportunities for biological upcycling, as the sludge contains high amounts of nutrients, energy and valuable biochemicals, making it an ideal food for extractive species. Sludge has been proposed as a feed stock for polychaete production, which in turn can be utilized live in shrimp aquaculture or as an aquafeed ingredient. However, the biosafety of such value chains has not yet been addressed. We conducted an experiment exposing the polychaete Hediste diversicolor to aquaculture sludge spiked with four different fish pathogens (Mycobacterium salmoniphilum, Yersinia ruckeri, Infectious Pancreatic Necrosis (IPN) and Infectious Salmon Anaemia (ISA)) known to cause diseases in Atlantic salmon (Salmo salar L.). Moreover, we assessed whether heavy metals and other potentially hazardous elements present in fish sludge bioaccumulates in the polychaetes. Neither of the bacteria nor viruses could be detected in the polychaetes after 14 days of continuous exposure. Seven of the 15 elements we analysed showed bioaccumulation factors significantly below one, meaning biodilution, while the other eight did not differ from one, meaning no bioaccumulation. None of the elements showed a significant bioaccumulation. Further on, none of the heavy metals found in the polychaetes at the end of our experiment exceeded the EU regulatory maximum levels for fish feed ingredients. The current results suggest that a H. diversicolor can reared on aquaculture sludge, and aquaculture sludge may serve as feed stock for polychaete production without the product exceeding EU regulations for contaminants in animal feed.publishedVersio
Impacts of marine heatwaves in coastal ecosystems depend on local environmental conditions
Get PDFMarine heatwaves (MHWs), increasing in duration and intensity because of climate change, are now a major threat to marine life and can have lasting effects on the structure and function of ecosystems. However, the responses of marine taxa and ecosystems to MHWs can be highly variable, making predicting and interpreting biological outcomes a challenge. Here, we review how biological responses to MHWs, from individuals to ecosystems, are mediated by fine-scale spatial variability in the coastal marine environment (hereafter, local gradients). Viewing observed responses through a lens of ecological theory, we present a simple framework of three ‘resilience processes’ (RPs) by which local gradients can influence the responses of marine taxa to MHWs. Local gradients (1) influence the amount of stress directly experienced by individuals, (2) facilitate local adaptation and acclimatization of individuals and populations, and (3) shape community composition which then influences responses to MHWs. We then synthesize known examples of fine-scale gradients that have affected responses of benthic foundation species to MHWs, including kelp forests, coral reefs, and seagrass meadows and link these varying responses to the RPs. We present a series of case studies from various marine ecosystems to illustrate the differential impacts of MHWs mediated by gradients in both temperature and other co-occurring drivers. In many cases, these gradients had large effect sizes with several examples of local gradients causing a 10-fold difference in impacts or more (e.g., survival, coverage). This review highlights the need for high-resolution environmental data to accurately predict and manage the consequences of MHWs in the context of ongoing climate change. While current tools may capture some of these gradients already, we advocate for enhanced monitoring and finer scale integration of local environmental heterogeneity into climate models. This will be essential for developing effective conservation strategies and mitigating future marine biodiversity loss.publishedVersio
Zooplankton link climate to capelin and polar cod in the Barents Sea
Get PDFCapelin (Mallotus villosus) and polar cod (Boreogadus saida) hold a fundamental position in the Barents Sea ecosystem as consumers of zooplankton while serving as forage fish for the commercial and ecological key species Atlantic cod (Gadus morhua). The ongoing warming and Atlantification of the Barents Sea, along with increasing net primary production, makes previously inaccessible northern areas available as feeding grounds for capelin. The opposite effect is anticipated for the ice-dependent polar cod. The transport of Atlantic water with boreal plankton from the Norwegian Sea is important for sustaining biodiversity and production in the Barents Sea. A decline of the medium-sized mesozooplankton biomass to a low level during 2016 to 2022 coincided with a strongly decreasing summer volume transport with the Atlantic Current. The low biomass of medium-sized zooplankton observed in later years raises concern about the feeding conditions now experienced by the higher trophic levels. Both capelin and polar cod feed predominantly on lipid rich sub-Arctic and Arctic zooplankton species. We found a significant inverse relationship between capelin and mesozooplankton biomass and a clear dietary shift from smaller to larger predator size. Smaller capelin (<12 cm) contained a comparatively higher proportion of copepods, dominated by Calanus glacialis, followed by C. finmarchicus and Metridia longa (copepodite stages IV-VI). As the capelin grow, their diet switches towards larger zooplankton, primarily euphausiids (mainly Thysanoessa inermis). All age groups of polar cod fed heavily on pelagic amphipods (mostly Themisto libellula) in addition to copepods and euphausiids, and to some degree also on fish, thus displaying a higher trophic position than capelin. Capelin growth from age 1 to 2 was negatively associated with their abundance at age 2, but positively related to stomach fullness for 2-year-old fish, indicating density-dependent growth. While our study reveals interactions between capelin and zooplankton, such signals between polar cod and their prey were not evident.publishedVersio
Lyd i lakseoppdrett
Get PDFLydnivået på oppdrettsanlegg har økt ettersom anleggene har blitt større, mer mekanisert og bruker en rekke støyende maskiner (arbeids- og brønnbåter, pumper og kompressorer). Lyd brer seg godt under vann og kan høres av fisk. Vi ønsket å beskrive denne menneskeskapte lyden i mer detalj ettersom den muligens påvirker atferd, velferd, helse og produksjonen av oppdrettsfisken, eller andre dyr i nærheten av anlegget. Vi målte lydnivå (SPL = sound pressure levels) under vann ved 10 ulike oppdrettsanlegg for laks i Norge, hvorav 4 åpne merder, 2 semi-lukkede merder og 4 landbaserte karanlegg. Laksen kan høre mye av lyden som ble målt (nivå, frekvens og mangfold). Støyen varierte betydelig mellom anlegg og over tid og rom innenfor lokaliteter. Lydtrykksnivåene ble beregnet som kvadratisk gjennomsnitt (RMS= root mean square) for frekvensbåndene laksefisk hører best (20-100 Hz og 100-500 Hz). I lukkede merder var lyden kraftigst i frekvensområdet 100-500 Hz hvor typiske SPLRMS verdier lå i området 123-134 dB re 1 µPa. Men lyden i støyende perioder var betydelig høyere, med SPLRMS verdier på 143-154 dB re 1 µPa. I kar var det lavere nivå enn i lukket merd og mer lyd i det laveste frekvensområdet (typiske SPLRMS på 112-127 dB re 1 µPa), forøket i støyende perioder (SPLRMS verdier på 131-135 dB re 1 µPa). I landanleggene var lyden mer forutsigbare enn i sjø. I de åpne merdene var det mindre støy enn i både lukket og landanlegg, likere verdier mellom de to frekvensbåndene (typiske SPLRMS verdier på 95-105 dB re 1 µPa). Men, i åpne sjøanlegg var det derimot stor variasjon mellom dag og natt, hvor støy var knyttet til besøk av arbeids- og brønnbåter. Lydnivåer i støyende perioder hadde SPLRMS verdier på 138-157 dB re 1 µPa med mest støy i det lave frekvensområdet 20-100 Hz. Når brønnbåter manøvrerte langs en merd og lydenergien ble kumulert over tid, i form av lydeksponerings nivået (SEL), som et mål på total lyd-dose, kunne verdiene komme opp i 144-145 dB re 1 µPa2s, 20–1000 Hz over 60 s. Meget støyende forhold gitt som spisstrykket ble beregnet for 175 dB re 1 µPa ble observert ved to anledninger: under sprengning ved et storsmoltanlegg på land, og inne i en lukket merd nær en undervannsluke som ble lukket med et smell (mekanismen ble deretter ombygd for å bli stillere). I et bonusmateriale fra sjøanlegget Hattasteinen ble det målt 1 s SPLRMS på 158 dB re 1µPa (spisstrykk: 175 dB re 1µPa) ved detonasjon av 850 kg sprengstoff omtrent 1500 m unna. Bortsett fra i disse tre relativt uvanlige tilfellene, målte vi ikke nivåer av lyd som vi tror kan gi betydelig hørselstap eller akustisk skade hos laks. Men lydnivåer målt i de fleste systemer, spesielt plutselige lyder vil ofte gi betydelige atfredsresponser hos fisken, illustrert av fluktresponser observert ved sprenging og lukelukking. Generelt var lydene vi målte innenfor samme type og nivåer som tidligere er rapportert fra oppdrettsanlegg, men arbeidet beskriver betydelig mer detaljer om lyden og sammenhenger mellom tid på døgn, type anlegg, støyende utstyr og fartøy. Det gjenstår å vurdere om de støyende oppdrettsmiljøene kan føre til akklimering og/ eller kronisk stress. Det er behov for mer kunnskap for å forstå de samvirkende effektene av lyd og varighet på atferd, helse- og velferd hos oppdrettet laksefisk.Lyd i lakseoppdrettpublishedVersio
Phytoplankton bloom distribution and succession driven by sea-ice melt in the Kong Håkon VII Hav
Get PDFThe existence of ice-edge phytoplankton blooms in the Southern Ocean is well described, yet direct observations of the mechanisms of phytoplankton bloom development following seasonal sea-ice melt remain scarce. This study constrains such responses using biological and biogeochemical datasets collected along a coastal-to-offshore transect that bisects the receding sea-ice zone in the Kong Håkon VII Hav (off the coast of Dronning Maud Land). We documented that the biogeochemical growing conditions for phytoplankton vary on a latitudinal gradient of sea-ice concentration, where increased sea-ice melting creates optimal conditions for growth with increased light availability and potentially increased iron supply. The zones of the study area with the least ice cover were associated with diatom dominance, the greatest chlorophyll a concentrations, net community production, and dissolved inorganic carbon drawdown, as well as lower sea surface fugacity of CO2. Together, these associations imply higher potential for an oceanic CO2 sink due, at least in part, to more advanced bloom phase and/or larger bloom magnitude stemming from a relatively longer period of light exposure, as compared to the more ice-covered zones in the study area. From stable oxygen isotope fractions, sea-ice meltwater fractions were highest in the open ocean zone and meteoric meltwater fractions were highest in the coastal and polynya zones, suggesting that potential iron sources may also change on a latitudinal gradient across the study area. Variable phytoplankton community compositions were related to changing sea-ice concentrations, with a typical species succession from sympagic flagellate species (Pyramimonas sp. and Phaeocystis antarctica) to pelagic diatoms (e.g., Dactyliosolen tenuijunctus) observed across the study area. These results fill a spatiotemporal gap in the Southern Ocean, as sea-ice melting plays a larger role in governing phytoplankton bloom dynamics in the future Southern Ocean due to changing sea-ice conditions caused by anthropogenic global warmingPhytoplankton bloom distribution and succession driven by sea-ice melt in the Kong Håkon VII HavpublishedVersio
Virus-specific antibody secreting cells reside in the peritoneal cavity and systemic immune sites of Atlantic salmon (Salmo salar) challenged intraperitoneally with salmonid alphavirus
Get PDFThe development and persistence of antibody secreting cells (ASC) after antigenic challenge remain inadequately understood in teleosts. In this study, intraperitoneal (ip) injection of Atlantic salmon (Salmo salar) with salmonid alphavirus (WtSAV3) increased the total ASC response, peaking 3–6 weeks post injection (wpi) locally in the peritoneal cavity (PerC) and in systemic lymphoid tissues, while at 13 wpi the response was only elevated in PerC. At the same time point a specific ASC response was induced by WtSAV3 in PerC and systemic tissues, with the highest frequency in PerC, suggesting a local role. Inactivated SAV (InSAV1) induced comparatively lower ASC responses in all sites, and specific serum antibodies were only induced by WtSAV3 and not by InSAV1. An InSAV1 boost did not increase these responses. Expression of immune marker genes implies a role for PerC adipose tissue in the PerC immune response. Overall, the study suggests the Atlantic salmon PerC as a secondary immune site and an ASC survival niche.publishedVersio
Exploring the effects of methodological choices on the estimation and biological interpretation of life history parameters for harbour porpoises in Norway and beyond
Get PDFThis study investigates effects of subtle methodological choices on the estimation and biological interpretation of age, growth and reproductive parameters for harbour porpoises. The core analyses are based on a focal Norwegian data set built on samples from 134 harbour porpoises caught incidentally in gillnet fisheries along the Norwegian coast during autumn 2016 and spring 2017. Two contrasting practices for interpretation of seasonal and ontogenetic characteristics of tooth growth layer formation resulted in significant age differences among spring samples of young porpoises and for older animals across seasons. In turn, these differences affected estimates of age at maturity and asymptotic lengths, respectively. We also found significant differences in male age at maturity between two well-documented maturity criteria and between mathematical estimators of age at maturity for both sexes. Two different criteria for corpus albicans classification furthermore resulted in different patterns of ovarian corpora accumulation, which may affect some estimates of fecundity rates and contaminant loads. Both corpora accumulation patterns were also found in reanalysed data from German and Greenlandic porpoises. Based on tabulated overviews of methodological choices made in previous harbour porpoise studies, we argue that several of the issues mentioned above have wider relevance and may affect the validity of meta-analyses as a tool for estimating harbour porpoise sensitivity to extrinsic pressures. Differences in cause of death (COD) composition between data sets can have a similar effect. We demonstrate this in a meta-analysis of published harbour porpoise pregnancy rates, showing significantly higher values for trauma-killed samples compared to samples comprising mixed COD categories. COD also affected the estimated impacts of three previously analysed extrinsic predictors as well as an added predictor for vessel noise levels. We discuss the potential contributions of methodological, biological and anthropogenic factors in shaping observed regional differences in estimates of harbour porpoise life history parameters.publishedVersio
Antioxidant and osteoinductive properties of organic selenium in microdiets for gilthead seabream (Sparus aurata) larvae
Get PDFThis study investigated the effect of yeast derived selenium (Se) dietary supplementation on larval performance, whole body mineral contents, lipid peroxidation, fatty acid profiles, expression of antioxidants and bone biomarkers genes, mineralization and skeletal anomalies in gilthead seabream (Sparus aurata) larvae. Five experimental microdiets containing 1.4, 6.1, 9.2, 12.0 and 14.0 mg Se/kg diets were fed to triplicate groups of larvae (total length: 7.26 ± 0.83 mm, 30 dph) for 21 days. Larval Se levels increased proportionally to the elevation of dietary Se. Those fed with dietary Se level at 6.1 mg/kg had a higher growth performance than those fed with non-supplemented diet (1.4 mg/kg), then reached a plateau from larvae fed with Se6.1 to Se14 diet although growth was not significantly affected by different diets. In addition, larval survival was not significantly affected. However, larvae fed the lowest Se levels showed a significant increase in lipid peroxidation, the downregulation of antioxidant genes, a reduction in polyunsaturated fatty acids (PUFA) contents and the highest incidence of skeletal anomalies. While increase up to 6.1–12 mg Se/kg, reduced oxidative stress, increased PUFA, vertebral mineralization, up-regulated antioxidant and bone metabolism related genes and contributing to reduce skeletal anomalies of larvae. However, further increase in dietary Se up to 14 mg/kg led to the lowest gpx, cat and alp expressions, in agreement with a lower mineralization. These findings suggest, dietary Se level at 6.1 mg/kg would be the minimum dietary Se level required in microdiets for gilthead seabream larvae. Thus, the study demonstrates the importance of dietary Se for bone metabolism and mineralization due to its antioxidant and osteo-inductive properties.publishedVersio
Does the processing of black soldier fly larvae meal affect the amino acid solubility in Atlantic salmon (Salmo salar)?
Get PDFThe present work aimed to evaluate protein and amino acid (AA) digestibility/solubility of different black soldier fly larvae (BSFL) based meals for Atlantic salmon in vivo and in vitro. Three types of insect meals that had been through different processing techniques were included: microwave full fat BSFL meal (BSFM), defatted BSFL meal with an enzymatic pre-treatment (BSFE) and a defatted BSFL meal without enzymatic pre-treatment (BSFH). For the in vivo digestibility studies only two ingredients (BSFE and BSFH) were used. The experimental diets for the different ingredients were prepared by mixing a control diet with BSFL meals at an 80:20 ratio. The in vitro method implied a two-stage hydrolysis involving both gastric simulation (acid hydrolysis) and gastrointestinal simulation (acid hydrolysis followed by alkaline hydrolysis), using enzymes extracted from salmon. The results showed that the AA solubility was higher in the gastrointestinal phases than the gastric phase alone, showing the importance of having both phases in vitro solubility for an effective protein breakdown. The AA solubility of different insect-based meals showed that neither partial defatting nor the addition of enzymatic treatment impacted the protein and AA solubility. The in vivo trial (56 days) recorded no differences between fish fed diets containing BSFE and BSFH for growth or body indices. The protein and AA apparent digestibility were similar for both BSFE and BSFH ingredients. Thus, in the current study no differences in nutrient digestibility were observed due to different processing methods employed to BSFL meal both in vivo and in vitro.publishedVersio
Minstestørrelse på rensefisk ved utsett i oppdrettsnøter for å hindre rømming - Del 1: Bergnebb og små grønngylte
Get PDFRapporten beskriver hvilken minstestørrelse av bergnebb og grønngylte som må benyttes ved utsett i oppdrettsnøter med en gitt maskeåpning for å hindre rømming. Minstestørrelsene er basert på trengingsforsøk i tank og modellberegninger med analyseverktøyet FISHSELECT (kun bergnebb). Beregningene ble gjort for ubehandlet (dvs. uten impregnering), knuteløst oppdrettsnotlin av polyamid med en nominell maskeåpning på hhv 26, 30, 40 og 50 mm. Maskeåpningene som er oppgitt i notsertifikatet er målt på tørt notlin. Målinger viste at maskeåpningen i våt tilstand var fra 14-18% større enn i tørr tilstand.Minstestørrelse på rensefisk ved utsett i oppdrettsnøter for å hindre rømming - Del 1: Bergnebb og små grønngyltepublishedVersio