Siste publikasjoner ved Institutt for naturvitenskapelige fag

Biological nitrogen fixation is a key process impacting productivity in the Baltic Sea. Most studies of this process have focused on filamentous cyanobacterial diazotrophs, leaving the ecological roles of non-cyanobacterial diazotrophs (NCDs) poorly resolved. Here, we investigate the diazotrophic community across different primary productivity phases (productive and post-productive) and within distinct particle fractions (suspended and sinking) across the Northern Baltic Proper, Gulf of Finland, and Gulf of Bothnia. Using nifH gene amplicon sequencing, we show that NCDs dominate the diazotrophic community, accounting for 81%–100% of all sequences, whereas filamentous cyanobacteria contribute up to 19% and are largely restricted to the post-productive phase. Productivity phases emerged as a descriptor for structuring the diazotroph community composition, with Thermodesulfobacteriota dominating during the productive phase (up to 64.8%) and Gammaproteobacteria during the post-productive phase (up to 77.1%). Suspended and sinking particles were broadly similar, yet each exhibited distinct taxon-specific enrichments between phases, which might suggest different ecological strategies within the major NCD groups. This suggests potential roles in aggregate-associated nitrogen fixation; such mechanisms could include polysaccharide degradation and anaerobic metabolism. Phytoplankton composition (18S rRNA) varied between productivity phases and co-occurred with shifts in the diazotrophic community, suggesting potential cross-domain interactions. Comparing across basins, we did not observe significant differences in diazotroph community composition, except for a higher relative abundance of cyanobacterial diazotrophs in the Gulf of Finland. Taken together, our findings show diverse NCD lineages inhabiting particle-associated niches, highlighting the need to further investigate their ecological significance in the Baltic Sea. IMPORTANCE Nitrogen is a key nutrient that supports life in marine ecosystems. Traditionally, nitrogen fixation in the Baltic Sea has been attributed mainly to filamentous cyanobacteria. In this study, we show that non-cyanobacterial diazotrophs dominate the nitrogen-fixing community across productivity phases. We also demonstrate that suspended and sinking particles provide habitats for these microorganisms, allowing different groups to thrive under varying conditions. We further show that shifts in the phytoplankton community co-occur with changes in the diazotrophic composition. Together, our findings reveal that nitrogen fixation in the Baltic Sea extends beyond filamentous cyanobacteria and involves a diverse particle-associated diazotrophic community. Understanding the role of these overlooked microorganisms is important for predicting how nitrogen cycling will respond to ongoing changes, such as warming, eutrophication, and shifts in plankton communities.

Abstract Marine protected areas (MPAs) are globally seen as useful tools to preserve marine biodiversity and restore depleted fisheries. However, high fishing pressure around MPAs could disfavour individuals with large home ranges crossing protected area borders and thereby cause a shift towards less mobile individuals within MPAs. Eventually, this could reduce the benefits of protected areas for both conservation (i.e. phenotypic diversity) and fisheries (i.e. spillover). Here, we tested whether MPAs select against highly mobile phenotypes of European lobster (Homarus gammarus) by using multi-year data (2006–2019) on captures and recaptures of 8020 tagged individuals collected at three MPA-fished area pairs along the Norwegian Skagerrak coast. By applying spatially explicit capture-recapture models to this dataset, we could estimate sigma, a model parameter that reflects the spatial range of the populations, and test for temporal, sex, and size-specific variation in sigma across populations. We found no general evidence that lobsters exhibited higher sigma values in fished areas than in MPAs, nor that spatial range consistently declined through time within protected areas. Although models including temporal variation in sigma performed better than time-constant models, significant declines through time were only statistically supported for male lobsters at one MPA. Furthermore, sex- and size-specific mobility patterns varied markedly among populations. Overall, while selection against mobility may occur in some protected populations, our results suggest that this is not a general consequence of MPA implementation and that the mechanisms regulating lobster spatial behaviour are likely context dependent.

Ticks are important vectors of zoonotic pathogens in Europe, but knowledge regarding the presence of Rickettsia spp. and Bartonella spp. in questing Ixodes ricinus in Norway remains limited. This study investigated the occurrence of these bacteria in ticks collected across the Norwegian distribution range of I. ricinus. A total of 564 adult ticks and 3930 nymphs (393 pools) collected in seven counties were analysed by real-time PCR. Rickettsia spp. were detected only in adult ticks, with an overall prevalence of 3.9 % (22/564). Infected ticks were identified in only two counties, Østfold and Agder, with a prevalence of 11.2 and 10.9 %, respectively. Species-specific analysis confirmed R. helvetica in 77.3 % (17/22) of the positive samples. Rickettsia spp. were not detected in any nymph pools. Bartonella spp. were detected in 0.5 % (3/564) of adult ticks, representing the first report of Bartonella spp. in questing I. ricinus in Norway. Infected ticks were found in three counties, Østfold, Telemark, and Nordland. Bartonella spp. were not detected in any nymph pools. These findings demonstrate that Rickettsia spp. and Bartonella spp. are present in questing adult ticks in Norway, highlighting the importance of continued surveillance of emerging tick-borne pathogens in northern Europe.

Ocean alkalinity enhancement (OAE) is a possible climate mitigation technology that can remove CO2 from the atmosphere. Here, we studied the feasibility of OAE in a case study using serpentinite gangue and examined the carbon dioxide removal (CDR) potential, the legal requirements, and the economic viability. The carbon emission factor was estimated to stay below 70 kg CO2e t−1 CO2 removed. Permitting would require the risks for marine ecosystems at the site to be carefully considered. Under the assumptions of this case study, OAE would require CDR credit prices higher than 100 € t−1 CO2 removed to be economically viable. Commitments of public and private actors to buy OAE credits would reduce market uncertainty and could be a way to promote OAE if the environmental impacts are acceptable.

Understanding population structure and clarifying species boundaries are essential for the sustainable management of exploited marine species. Although genomic resources for shallow-water taxa have expanded rapidly, open-water species remain comparatively understudied. Here, we present a comprehensive genomic analysis of the white anglerfish (Lophius piscatorius), a commercially important species that occupies a wide depth range. We examined genetic structuring and verified species identity across its distribution range in the North Atlantic and Mediterranean. We combined whole-genome sequencing of selected individuals with targeted SNP genotyping of 897 specimens from 35 locations. Our results support a panmictic or nearly panmictic population of white anglerfish throughout the Northeast Atlantic, consistent with earlier studies, here extended northward to about 68° N. We found no evidence of local adaptation or selection. Like earlier studies, we detected apparently misclassified specimens of the closely related black anglerfish (L. budegassa) and extensive hybridization with up to 20% hybrids in local samples from around the Celtic Sea and nearby waters. Most or all hybrids appear to be first generation (F1), with a few potential backcrossed individuals of less certain identification. Demographic analyses indicate a recent colonization of the North Atlantic, with black anglerfish diverging more recently and maintaining a smaller effective population size. These results underscore the value of integrating genomic tools into monitoring frameworks to improve species identification, delineate population units, and inform sustainable fisheries management.

Life skills like problem-solving, communication, collaboration, and creative and critical thinking are closely tied to scientific practices in science education. However, there is ongoing debate about how to define and operationalize scientific practices for implementation in schools and teacher education. In Norway, these practices are a core element of the science curriculum, but their definition remains vague. To address this, we used a design-based research approach to develop a skills-based tool for teaching and learning scientific practices in schools and teacher education. The tool highlights twelve interrelated skills that support students’ engagement in scientific practices and their reflection on scientific processes. We describe the process of designing and developing the teaching tool, our design analysis of why and how the tool evolved, and three design principles to inform the development of a skills-based teaching tool to practice science. These principles highlight three critical features of the tool: it is dynamic and flexible, initiates active learning, and provides support for teachers.

This study explores pre-service teachers' (PSTs) storylines regarding their engagement with programming as a new component of mathematics and science education in Norwegian schools. To familiarize fourth-year PSTs with programming and exploratory teaching approaches, a 4-week period of experiential learning was conducted. Designed to elicit reflection on the role of the teacher, this 4-week period culminated in the PSTs working in groups to plan and deliver instruction for high school students. We have used narrative inquiry to investigate the positioning of PSTs regarding programming, the use of programming in teaching, and exploratory approaches to teaching programming. The study is based on the weekly reflection logs of nine PSTs. In this paper, we chose one PST (we called Thor, Linn, and Hans) from each group and narrated how their positioning unfolded over the four weeks. Understanding PSTs’ positioning when faced with changing curricula may help teacher educators in supporting prospective teachers.

Long-term animal re-identification (ReID) must remain robust to gradual morphological evolution and seasonal appearance shifts. Although recent vision–language models provide strong pretrained visual representations, adapting them to longitudinal ecological settings remains challenging, particularly under identity and temporal distribution shifts. We present a parameter-efficient CLIP adaptation framework for animal ReID and introduce a continuous metadata-conditioning mechanism that incorporates numerical attributes directly into the prompt representation during training. While low-rank visual adaptation, prompt-based supervision, and cross-modal alignment provide the adaptation framework, the proposed metadata-conditioning strategy constitutes the primary methodological contribution. By preserving the continuous structure of numerical metadata rather than discretizing it into textual categories, the proposed approach enables smooth modulation of the embedding space during training while maintaining a purely visual inference pipeline. Experiments on a seven-year longitudinal fish dataset and multiple wildlife benchmarks demonstrate improved performance under closed-set, open-set, and time-aware evaluation protocols. The results demonstrate that continuous metadata conditioning improves robustness to longitudinal appearance variation and temporal distribution shifts, while parameter-efficient adaptation enables a purely visual inference pipeline without requiring metadata at test time.

Tick-borne diseases constitute a major group of emerging vector-borne infections and represent a growing public health concern in many European countries. In Europe, the most clinically significant agents transmitted by Ixodes ricinus are tick-borne encephalitis virus (TBEV) and Borrelia burgdorferi sensu lato, the causative agents of tick-borne encephalitis and Lyme borreliosis, respectively. Ixodes ricinus also serves as a vector for other pathogenic microorganisms, including louping-ill virus (LIV) and Anaplasma phagocytophilum. Various endosymbionts, such as Wolbachia pipientis and Midichloria mitochondrii, are also found in ticks. In this study, we assessed the prevalence of TBEV, LIV, B. burgdorferi s. l., A. phagocytophilum, W. pipientis, and M. mitochondrii in 3437 I. ricinus ticks collected from five locations in Norway. The estimated pool prevalence of TBEV ranged from 0 to 0.4% in nymphs, while the prevalence in adults ranged from 0 to 7.1%. In contrast, no LIV was detected. Borrelia burgdorferi s. l. was detected at all sites, with prevalences ranging from 3.4% to 14.3% (overall prevalence of 5.7%), representing four genotypes (B. afzelii, B. garinii, B. valaisiana and B. burgdorferi sensu stricto). Estimated pooled prevalence of A. phagocytophilum was 5.1% in nymphs, while the overall prevalence in adults was 19.8%. In adult ticks, W. pipientis and M. mitochondrii occurred at overall prevalences of 11.0% and 84.1%, respectively. In only 12.3% of ticks, none of the agents investigated were detected. However, 32.6% of the ticks showed co-occurrence of infectious agents and/or the endosymbionts. Thus, this underscores the need for improved understanding of microbial interactions influencing tick-borne disease outcomes.

In the context of global amphibian declines, there is need to map local amphibian populations to establish baseline knowledge of potential future species losses. Even in well-studied lakes and ponds within popular recreational areas near urban centres, information on amphibian occurrence can be limited. In this study, the local distributions of Lissotriton vulgaris, Rana temporaria and Bufo bufo were assessed using eDNA analysis in two city forest areas of Kristiansand, Southern Norway. In the forest Baneheia, all three species were detected, although R. temporaria was present in only half of the lakes. In the forest Jegersberg, L. vulgaris was detected in nearly all lakes while B. bufo only in fewer than half, and R. temporaria was not detected. Our results support the public observations system Artsobservasjoner.no that R. temporaria is uncommon in the coastal area of Kristiansand. Comparison of active netting with eDNA analysis indicated that eDNA is a more reliable method for detecting amphibians. Interestingly, larvae of L. vulgaris were observed in one of the lakes in Baneheia inhabited by Salmo trutta, in a shallow bay with dense aquatic vegetation, demonstrating that newts can successfully reproduce alongside trout under certain conditions.

Computer vision can transform wildlife monitoring by automating phenotyping and individual identification. Achieving this, however, depends on access to large, well-curated image datasets that capture natural variation across individuals and years. Here, we present Melops, a longitudinal dataset comprising 24 578 images of 9 861 individual corkwing wrasse, Symphodus melops, collected over seven years through a capture–mark–recapture survey. Each fish was PIT-tagged for re-identification and photographed from both sides against a standardized white background with a colour reference. Alongside the images, we provide metadata including body length, sex, and reproductive state. To support deep learning applications, the dataset includes both the original photographs and automatically cropped images focusing on the whole fish or specific body regions. Together, these resources provide a foundation for developing computer vision methods for individual re-identification, colour pattern analysis, sex classification and other visual phenotyping tasks. Beyond this species, Melops can serve as a model for similar datasets in other taxa. Because it contains thousands of individuals with repeated observations, it provides a rare opportunity to explore temporally aware re-identification and phenotypic change in wild fish.

Background Ticks are important vectors of zoonotic pathogens, posing a growing threat to animals and humans in Europe. In Norway, the tick species Ixodes ricinus is expanding its range, increasing the risk of tick-borne infections. This study aimed to estimate the seroprevalence of IgG antibodies against Borrelia burgdorferi sensu lato (s. l.), tick-borne encephalitis virus (TBEV), and Anaplasma phagocytophilum in domestic dogs residing in Norway, and to assess their potential role as sentinel species for tick-borne pathogen surveillance at the northernmost limit of I. ricinus’ geographical range. Serum samples (n = 433) from domestic dogs were collected across 15 counties between 2016 and 2023 and analysed using immunoblot assays. Results Overall, 38% of the dogs were seropositive for one or more tick-borne pathogens. The seroprevalence was 20% for B. burgdorferi s. l., 19% for TBEV, and 11% for A. phagocytophilum. Statistically significant regional differences were observed for the latter two pathogens. Conclusions The findings indicated widespread exposure of Norwegian dogs to tick-borne pathogens and support their role as sentinel species for assessing human risk. Continued surveillance and preventive measures are recommended to reduce tick infestation and pathogen transmission to both dogs and humans.

Small pelagic fish (SPF) are critical to the trophodynamic structure and function of marine systems and support some of the most valuable and socially important fisheries worldwide. Their “boom and bust” population dynamics, shifts in distribution, and importance as forage resources for other fish stocks place unique challenges to assessing and managing SPF. In response to these challenges, an international working group was formed in 2019 to foster collaboration aimed at closing key knowledge gaps in the ecology and sustainable management of SPF. Here, that group reviews progress made over the last ~10 years and identifies priorities for the next stage of coordinated international collaboration. Key research needs include: (i) enhancing monitoring programs to capture shifts in SPF distribution and incorporating new technologies, from molecular tools and digital imaging to biophysical and ecological modelling, (ii) improving data sharing to better understand life-history bottlenecks and cross-regional population dynamics, (iii) advancing process-based studies on oceanic and trophodynamic interactions to clarify the ecological roles of SPF as both predators and prey, and (iv) conducting bioeconomic and risk analyses to assess the vulnerability of fishing-dependent human communities to environmental and fish population fluctuations. A key pathway forward involves integrating mechanistic ecological knowledge, ecosystem and bioeconomic modelling, and social-ecological frameworks into real-time, adaptive, and equitable management approaches. This integration will be essential for developing resilient, ecosystem-based fisheries management capable of anticipating tipping points, accommodating non-stationary population dynamics, and ensuring sustainability under future climate and socio-economic uncertainties.

Background Borrelia burgdorferi sensu lato (s. l.) and Neoehrlichia mikurensis are the most prevalent pathogenic bacteria found in Ixodes ricinus in Norway. Here we evaluate the prevalence of both bacteria and the density of infected ticks, key factors to assess the human infection risk. The study was performed in one location in southern Norway. Results An overall prevalence of 12% for B. burgdorferi s. l. and 8% for N. mikurensis was found. The most prevalent B. burgdorferi s. l. genospecies was Borrelia afzelii, followed by Borrelia burgdorferi sensu stricto and Borrelia garinii. The highest density of infected nymphs with B. burgdorferi s. l. was in May and the lowest was in November. In the case of N. mikurensis, the highest density of infected nymphs was found in September and the lowest in November. B. burgdorferi s. l. prevalence was negatively correlated with tick density. Conclusions Our results highlight the importance of assessing not only pathogen prevalences but also tick population densities. Extended periods of surveillance in questing ticks are necessary to understand the intricate dynamics of ticks and tick-borne pathogens.

Intraspecific diversity in life histories and movement behaviour can buffer population dynamics of animals against environmental change and potentially improve the reliability of ecosystem services such as fisheries yields. We used a combination of acoustic telemetry and genetics to study the movement behaviour of 2 sympatric ecotypes of Atlantic cod Gadus morhua across a wide range of body sizes (N = 389, body lengths = 35-101 cm), during their foraging season (July-December) within 3 subarctic fjords in northern Norway. As expected, most tagged fish belonged to a coastal ecotype (93%). In addition, a migratory Northeast Arctic ecotype was also seen in all 3 fjords during the foraging season (7%). On average, individuals belonging to the Northeast Arctic ecotype used deeper locations in the fjords compared to the coastal ecotype. The 2 ecotypes behaved similarly in terms of horizontal and vertical movements. Larger individuals were typically detected at more locations (i.e. a higher horizontal movement activity) and greater depths, while smaller individuals on average had more extensive vertical movements. Females (N = 200) and males (N = 189) showed similar movement behaviours. Our findings imply that conservation measures, such as marine protected areas, should connect shallow and deep fjord habitats to effectively preserve Atlantic cod. Similarly, the biodiversity impact of anthropogenic pressures such as fishing and aquaculture will likely depend on their specific location within fjords

Microbial communities are central to water quality, fish health, and operational stability in modular recirculating aquaculture systems (M-RAS). The composition and succession of microbial communities in the main production tank and the effluent were investigated during an Atlantic salmon grow-out period using 16S rRNA gene sequencing. Effluent from the aquaculture system was further reused for cultivation of Phaeodactylum tricornutum, enabling assessment of how effluent-derived microbial communities respond to algal growth conditions. In the main production tank, microbial communities showed an early shift from Rhodobacterales toward increasing dominance of Flavobacteriales, followed by a community assemblage with strong contributions by taxa of Thiotrichales and Chitinophagales. Operational disturbances, including reduced feeding and salinity adjustment, coincided with increased relative abundances of ASVs affiliated with Arcobacteraceae, Weeksellaceae, and Pseudoalteromonadaceae, taxonomic groups that include species described as opportunistic or pathogen-associated in marine fish systems. The effluent harboured a temporally variable microbial community throughout the grow-out period, characterized by fluctuations in the relative abundances of dominant orders such as Flavobacteriales, Enterobacterales, and Bacteroidales. Microbial communities in effluent studied during a two-week cultivation of P. tricornutum shifted toward taxa typical of algal phycospheres, including Caulobacterales and Rhodobacterales, which are often linked to mutualistic functions between algae and bacteria such as vitamin provision and nutrient remineralization. However, the effluent also harboured Bacteroidetes taxa (e.g., Maribacter, Zobellia, Aurantivirga), some of which have been reported in other systems to compete with diatoms for resources. Their presence during algal cultivation may therefore warrant consideration if the resulting biomass is intended for use in aquafeeds. These findings suggest that microbial community composition in M-RAS responds to operational adjustments, and that effluent reuse for algal cultivation not only enables resource recovery but also reshapes downstream microbial community assembly.

Harbour seals (Phoca vitulina) have a broad distribution in coastal ecosystems across the northern hemisphere. In southern Scandinavia, a lack of spatially-resolved data on harbour seal populations poses a major challenge for developing ecologically informed management frameworks, particularly in Norway, where populations are regulated using county-level administrative boundaries. In this study, we use haul-out data from 26 harbour seals tagged with GPS phone tags during the post-moult period to provide the first assessment of connectivity and movement across management boundaries in the Skagerrak–Kattegat region of southern Scandinavia. Specifically, we examined the frequency and timing of haul-out events relative to management units and quantified spatial networks of connectivity across national and sub-national jurisdictions. We reveal a high degree of spatial connectivity in the region, with haul-outs occurring over a broad, integrated network along the Skagerrak–Kattegat coastline. Generally, harbour seals in the region had a high probability of performing cross-boundary haul-out events, with individuals repeatedly transitioning across distinct Norwegian management units, as well as transnationally between Norway, Sweden and Denmark. This study offers critical insights into harbour seal movement ecology in this data-limited region, whilst also addressing an important topic of applied management. We demonstrate that the current management units in the Norwegian Skagerrak may not adequately reflect the spatiotemporal scales of harbour seal movement. Importantly, these findings can complement forthcoming genetic data and support efforts to redefine management units in the area. More broadly, our study illustrates how telemetry-based assessments of spatial connectivity can provide a powerful tool to inform management frameworks for other wide-ranging marine species facing similar conservation challenges.

Seaweed aquaculture is a growing blue sector that provides many benefits to society (e.g. biomass provision for food, feed and cosmetics) and the environment (e.g. eutrophication mitigation, carbon uptake and habitat provision). Successful and sustainable production expansion requires that these activities are operated within limits of acceptable change (LAC) i.e. align with ecological and social carrying capacity. Emerging from a three-round Delphi study, this work presents, from a Global North perspective, the most relevant 1) limiting variables from the socio-environmental spheres that influence the cultivation unit (inputs), such as high operating costs or underdeveloped markets or uncertain impacts from climate change, and 2) the negative impacts of aquaculture on environment and society (outputs), such as overhyped and unrealistic expectation for seaweed cultivation, conflicts with fisheries or pollution. Consolidated lists of these inputs and outputs are accompanied by specific thresholds beyond which unacceptable changes are likely to occur. These results are placed into a globally applicable holistic framework for a multidimensional assessment of seaweed aquaculture including barriers and carrying capacity, which has been outlined for the first time for seaweed cultivation. Our results emphasize the need to include socio-economic aspects into ecosystem approaches, like profitability or social license to operate – and the need for broad stakeholder participation. This study provides thus a directly useable lists of aspects to consider for cultivators and decision-makers. And as is as such a crucial contribution for the ongoing discourse on sustainable growth of this emerging blue sector.

Genetic divergence between populations and/or species is mainly driven by reproductive isolation, that is, reduced gene flow, due to either pre- and/or postzygotic barriers. In this study, we investigate the role of (i) reproductive ecological interactions and (ii) mechanisms of evolutionary isolation between two genetically differentiated populations of a coastal fish species, corkwing wrasse Symphodus melops, in a large semi-natural mesocosm basin over a 2-year period. Corkwing wrasse is one of the main cleaner fish species used by the salmon aquaculture industry in Europe, where translocation is a common practice. The parentage analysis performed on the group of offspring survivors at the end of the translocation experiment evidenced strong selective winter mortalities in hybrid offspring (with mixed parental origin). Additionally, it suggested unprecedented assortative mating patterns in corkwing wrasse. Fish of west Norwegian origin experienced stronger intensity of sexual selection and displayed higher relative reproductive success (RRS) than individuals of southern origin under the experimental conditions. Size of the breeder and alternative sneaking behavior in males are two phenotypic traits often selected to attract potential mates and maximize reproductive fitness. However, neither of them had a significant effect on offspring production. Hence, our results suggest that other traits related to mate choice and competition, not examined here, could play a major role. Our results revealed strong selection against hybrids and potential assortative mating between southern and western corkwing wrasses population as two major contemporary drivers reshaping the historical genetic divergence associated to founder events during post-glacial recolonization in Norway. We discuss the relevance of our findings for aquaculture-based fisheries enhancement systems, resource management and conservation.

Intraspecific diversity can profoundly shape ecological interactions, yet its role within complex food webs remains challenging to quantify. We explored how eco-evolutionary divergence within Atlantic cod (Gadus morhua), specifically between the resident Fjord and migratory North Sea ecotypes, influences food web structure and function in a coastal marine ecosystem. Using key trait differences, including growth rate, age and size at maturation, reproductive investment, and ontogenetic dietary shifts, we parameterized an allometric trophic network model with empirical data from the Norwegian Skagerrak. The high-resolution network comprised 148 trophic guilds and 2054 feeding links, permitting resolution of ecotype-specific interactions. We found pronounced intraspecific divergence: North Sea cod reached higher trophic position earlier, exerting greater interspecific influence, whereas Fjord cod retained higher early-stage biomass, intensifying intraspecific competition between ecotypes. Together, these complementary roles indicate that variation within a single species can both dampen and amplify food web interactions across life stages, enhancing ecosystem connectivity, and triggering cascading ecological effects. To sustain this natural buffer, conservation and management must move beyond species-level metrics and actively protect intraspecific diversity.

The mating system of the iconic Atlantic cod (Gadus morhua) has been described as a lek, a mating system where male–male agonistic interactions are expected. However, observing such behaviors directly in marine environments is challenging. So far, the evidence supporting the importance of agonistic interactions between males is mainly derived from laboratory studies with fish kept in close confinement, possibly elevating the observed levels and their perceived importance. In natural aquatic systems, agonistic interactions may be inferred from acoustic telemetry transmitters fitted with accelerometers, given that they are associated with high activity levels. A large telemetry dataset on Atlantic cod was collected during (i) a field study at two Western Norway spawning grounds from 2019 to 2024 and (ii) a close confinement net—pen study in 2019–2020. A total of 154 sexed mature Atlantic cod were tagged with acoustic transmitters fitted with accelerometers and depth sensors, yielding ~1.5 million accelerometer detections for subsequent activity analyses. In the net-pens, male cod showed much higher activity levels than females. Overall activity levels were reduced in the field, but male activity levels remained higher than those of females during the spawning period. A prominent feature of coastal cod spawning along the Norwegian coast is that males tend to dwell deeper than females. We therefore explored whether depth influenced activity patterns of males and females. This was indeed the case with males being more active than females at fish depths > 20 m and no sex-difference in activity levels closer to the surface (< 20 m depth). No sex difference in activity levels was found outside the spawning period. Our data suggest that male–male agonistic interactions, inferred from activity levels, are present on natural spawning grounds for Atlantic cod, albeit at reduced levels compared to levels exhibited in net–pen confinement. We hypothesize that the heightened activity levels of males compared to females when occupying deeper waters are related to their overall deeper distribution and territorial and agonistic behavior at these depths, agreeing with the lek description of the cod mating system.

Alternative reproductive tactics (ARTs) are consistent intrasexual differences in behavior that maximize reproductive success through different means. In corkwing wrasse (Symphodus melops), smaller males mimic female visual morphology (hereafter sneakers) to steal fertilizations from nest-building parental males (hereafter nesting males). We investigated whether this visual mimicry effectively deceived 47 nesting males across 4 sites by quantifying 2 agonistic responses (attack latency and attack frequency) to models depicting unfamiliar females, sneakers and rival nesting males. Contrary to expectations, nesting males exhibited faster agonistic responses towards female models, with lower attack latencies compared with both male types. Additionally, the relationship between model type and attack frequency varied between sites, with reduced attack frequencies at sites subject to increased levels of anthropogenic disturbance. These results provide evidence that nesting males can visually discriminate between females and sneakers even in the absence of behavioral cues, suggesting that visual mimicry alone may be insufficient for successful deception. This highlights the need to investigate alternative sensory modalities, such as behavioral mimicry, to explain the successful reproduction of sneaker males and the maintenance of ARTs in this species.

Spawning locations of marine fish set the initial conditions for processes that influence survival, abundance, distribution, and the structure of the adult populations. The prevailing paradigm suggests that fish spawning is aggregated in few and spatially well-defined geographic areas. While corroborated, this view is biased by the sampling strategy. Here, we challenge the main paradigm and analyze an extensive and unique 16-year dataset of egg catches along the entire Norwegian coast to examine spawning patterns of Atlantic cod (Gadus morhua). Our results reveal that cod populations exhibit persistent spawning aggregations throughout the entire coastline, spanning a large range of oceanographic conditions. Distinct regional patterns were identified, linking egg abundance to habitat characteristics, including temperature, salinity, distance from coastline, and advective potential of the spawning site, pointing to a high degree for local adaptations. We found that regional differences are driven by the cod spawning strategies that are directed more toward fresher, warmer, and less advective body of waters, going from North-Norway to the Skagerrak area. Collectively our results demonstrate that spawning in marine fish can comprise a series of events at multiple locations and times, each uniquely associated with oceanographic variables. This research provides a foundation for developing a new framework to characterize marine fish life cycle closure and population structure, offering a critical baseline for conserving coastal marine habitats.

There is a growing interest in understanding the thermal tolerance of ectotherms across life stages. Identifying the stages that are most sensitive can help develop more robust projections on the consequences of climate impacts to populations, as well as help guide management and conservation efforts. Here, we estimate upper and lower thermal tolerance (as Critical Thermal maximum, CTmax, and minimum, CTmin) of Atlantic bluefin tuna (Thunnus thynnus) larvae. This species is an iconic apex predator that exhibits regional endothermy during the adult stage, but thermal tolerance of larvae was unknown. CTmin and CTmax were estimated in larvae grown from wild eggs under laboratory conditions. The mean (±SE) CTmax and CTmin across all tested batches and developmental stages was 31.7 (±0.6) and 17.9 (±0.7)°C, respectively. Rate of temperature change (1.5, 3, 6, or 9 °C h−1) had no effect on the thermal tolerance estimates. Similarly, CTmin and CTmax were consistent across preflexion, flexion, and postflexion larval stages. The observed high inter-individual variability in CTmin and CTmax (11-13 °C) likely reflects methodological challenges related to the extreme sensitivity of the species to handling stress and confinement. Present and future thermal safety margin (by 2060) for larvae in the Balearic Islands are 3.6 (±0.6 SE) °C and 1.8 (±0.6 SE)°C, respectively. Future research should continue exploring alternative methods for estimating thermal limits and incorporate experimental designs with multiple stressors such as exposing well- and poorly-fed larvae to heatwaves and/or different light levels.

Understanding how animals respond to environmental stressors across their life cycle is essential for predicting species' vulnerability to climate change. Here, we systematically reviewed the literature to quantify the variation in research effort on different life stages in the field of conservation physiology. Specifically, we reviewed experimental studies measuring physiological and life-history responses to climatic stressors across three representative scientific journals: Conservation Physiology, Journal of Thermal Biology and Journal of Experimental Biology. Our systematic map of 1276 studies revealed a pronounced underrepresentation of studies on embryos, representing only 8% to 9% of studies. This pattern was remarkably consistent across all axes considered (i.e. journals, taxonomic groups, physiological traits and environmental stressors). We also found that 80% of studies only investigated single life stages, and over 5% of studies did not clearly report the life stage(s) used. Despite the increasing recognition of the ecological importance and sensitivity of early life stages to environmental stressors, we found no evidence that research on embryos has gained traction over the past decade (2013–2024). We argue that these ontogenetic biases likely reflect a combination of historical precedents and enduring methodological and logistical constraints that continue to shape research agendas. To build a more holistic understanding across the life cycle, we: (i) call for a paradigm shift placing embryos at the center of experimental agendas, (ii) outline emerging methodological advances that increase the feasibility of research on early life stages, (iii) demonstrate how studies on embryos align with ethical considerations for animal research, (iv) highlight perspectives for future evidence syntheses and study reporting and (v) promote investigations of the mechanisms underlying physiological variation across ontogeny. Closing the ontogenetic gap will be key to improving our ability to predict population-level impacts of climate change and guiding more effective conservation and management interventions.

Benthic organisms are important ecological receptors, playing fundamental roles across seafloor ecosystems, delivering some of the most important functions in the marine environment. Some of these key benthic functions include nutrient cycling, food provision for higher trophic levels, and carbon storage. Over the past 6 years, benthic monitoring has faced growing complexity, driven by diminishing funding and the constraints imposed by the COVID-19 pandemic. These challenges underscore the pressing need to recognize the enduring value of benthic time series in supporting monitoring, management, and modelling efforts. These long-term data sets have been critical to advance our current understanding into the areas of cumulative effects, conservation, management of Marine Protected Areas (MPAs), development of indicators, and assessment of climate-driven changes in marine ecosystems. Ongoing expert group discussions consistently affirm both the relevance and necessity of continuing to collect these vital data sets. However, the focus on emerging technologies and so-called ‘cutting-edge’ approaches sometimes leads to the undervaluation and compromising some of these long-term series. We contend that a comprehensive understanding of benthic ecology, essential for robust marine management, reliable numerical analysis, and taxonomic consistency, cannot be achieved without the continuity provided by long-term data. Such time series are indispensable for tracking patterns of change and assessing responses across diverse human activities and seafloor ecosystems. While our research has concentrated on soft sediment environments, many of the key principles and recommendations outlined here are broadly applicable to other ecosystem types.

Innledning: Studien undersøker bruken av casebasert læring som en metode i praksisveiledning. Case er definert som bioingeniørfaglig relevante scenarioer brukt i teoretisk eller praktisk veiledning. Studien hadde som mål å kartlegge i hvilken grad case brukes i ekstern praksis, hvordan de utarbeides og anvendes på tvers av fagområder og læringssituasjoner, samt å kartlegge praksisveiledernes syn på fordeler og ulemper ved bruk av case. Metode: En deskriptiv metode med både kvantitative og kvalitative tilnærminger ble benyttet. Metoden er basert på en spørreundersøkelse sendt til praksisveiledere i norske sykehus i perioden juni 2023 til januar 2024. Det var totalt 51 respondenter. Resultat: Studien viser at 55 % av praksisveilederne som svarte på spørreundersøkelsen bruker case i veiledningen. Casene er hovedsakelig selvutviklede og basert på problemstillinger fra laboratoriehverdagen. Fra veiledernes perspektiv fremmer casebasert læring studentenes kritiske tenkning, selvstendighet og evne til å integrere teori og praksis. Blant veiledere som i dag ikke benytter case, uttrykte mange interesse for å implementere case i veiledningsarbeidet, samt å samarbeide med kolleger om å utvikle slike caser. Konklusjon: Studien fremhever potensialet casebasert læring har til å gjøre praksisperioden mer engasjerende, fremme dybdelæring og til å kunne tilpasses til studentenes individuelle behov.

L-tryptophan (TRP), the precursor to serotonin (5-HT), modulates stress responsiveness and social behaviour in vertebrates. In cleaner fish such as lumpfish (Cyclopterus lumpus), these traits are integral to sea lice control in Atlantic salmon (Salmo salar) farming. We tested whether a TRP-enriched diet attenuates the stress response during commercial sea transfer and affects early cohabitation performance. Lumpfish were fed a control (5.2 g kg−1) or TRP-enriched diet (24 g kg−1, 4.6× control TRP) for 7 d, fasted for 2 d before transport, and then fed for 14 d after deployment in commercial net pens. Post-transfer stress was assessed using plasma cortisol concentrations. Telencephalic 5-HT neurochemistry was quantified as [5-HT], its metabolite 5-hydroxyindoleacetic acid [5-HIAA], and 5-HIAA/5-HT. Performance was evaluated based on growth, stomach content, and survival. TRP feeding increased 5-HIAA/5-HT after the pre-transfer phase, indicating increased serotonergic turnover, and reduced post-transport plasma cortisol, consistent with reduced HPI-axis reactivity. During 16 d of salmon cohabitation, TRP-fed fish showed a higher proportion of empty stomachs and slightly reduced growth, while cumulative survival did not differ between treatments. By the end of cohabitation, telencephalic 5-HIAA had converged back to similar means, while 5-HT remained significantly elevated in the TRP group. Overall, short-term dietary TRP enrichment reduced acute handling and transport stress in lumpfish without compromising survival, but prolonged exposure was associated with reduced feeding and growth. Dietary TRP enrichment thus appears promising as a pre-conditioning strategy to enhance lumpfish robustness during critical husbandry stages, although potential trade-offs with feeding motivation, growth, and cleaning behaviour require further study.

Atlantic cod Gadus morhua is a keystone species in the North Atlantic and Barents Sea ecosystems. Coastal Atlantic cod stocks have declined in recent decades, raising concerns about their recovery. Knowledge about cod behaviour, ecology and habitat use is vital to a management that ensures better costal cod population resilience and recovery. In this study, we aimed to quantify seascape use by Atlantic cod, using 3-dimensional acoustic telemetry to track 82 coastal cod (35-118 cm) from April through September in a 20 km 2 subarctic Norwegian fjord. We calculated continuous swimming trajectories in individual Atlantic cod with high precision (~15 m) and combined this with high-resolution bottom substrate classification and bathymetric maps with derivatives such as terrain slope and bathymetric position index. Bedrock and mixed gravel/stone substrates were among the least available habitats in the fjord, yet small cod (<55 cm) spent the most time in these habitats and avoided substrates containing mud and/or sand. Large cod (>55 cm) spent the most time in association with mud and sandy substrate. Large cod used deeper fjord parts than small cod, with only 24% overlap between the average depth distributions of the 2 size groups. Small cod were associated with steeper terrain slopes. The combination of the precise tracking method, detailed bathymetry and high-resolution habitat mapping provided new understanding of the size-dependent habitat use by Atlantic cod, and may serve as an important tool for marine research as well as coastal planning and management.

Background: Chronic stress in aquaculture poses major challenges to fish welfare, health, and productivity. Detecting compromised welfare early requires validated biomarkers that link operational welfare indicators (OWIs) to underlying neuroendocrine states, including allostatic load and stress coping capacity. The central serotonergic system is a promising candidate for such validation, given its conserved role in stress regulation across vertebrates. Methods: We sampled 40 Atlantic salmon ( Salmo salar ) from research-scale sea cages spanning a wide range of welfare states under production-relevant conditions. Fish were exposed to acute crowding during routine rearing operations immediately prior to sampling. Plasma cortisol was measured, along with serotonin (5-HT) concentration and turnover, proxied by 5-hydroxyindoleacetic acid (5-HIAA) and the 5-HIAA/5-HT ratio, in the brain stem and telencephalon. Associations among 5-HTergic variables, welfare indicators (OWI sum, scale loss, condition factor), and acute stress metrics (crowding time, cortisol) were analysed using principal component analysis (PCA), multivariate analysis of variance (MANOVA), and post hoc linear models. Results: Brain stem 5-HT concentration and turnover were consistently associated with welfare-related indicators and loaded strongly with these variables in multivariate space, indicating sensitivity to cumulative stress and compromised welfare. In contrast, telencephalic 5-HT turnover aligned primarily with acute stress metrics rather than welfare state. MANOVA and post hoc analyses confirmed these region-specific associations. A significant interaction for telencephalic 5-HIAA revealed that fish in poorer welfare states exhibited a blunted 5-HTergic response to acute stress compared with individuals in better welfare condition, consistent with reduced stress responsiveness under chronic strain. Conclusion: Our findings demonstrate a clear regional dissociation in central 5-HTergic stress processing in Atlantic salmon: brain stem 5-HT activity reflects chronic stress burden and welfare state, whereas telencephalic 5-HT turnover reflects acute stress reactivity conditional on baseline welfare. These results support the use of region-specific 5-HTergic measures as biologically grounded markers distinguishing chronic welfare compromise from functional acute stress responses in aquaculture, while emphasizing caution when interpreting acute stress reactivity in chronically stressed individuals.

The interconnectivity among coral reefs, seagrass ecosystems, and mangroves (CSM) forms a critical ecological continuum that sustains biodiversity, enhances resilience to environmental stressors, and supports coastal communities. This study reviews the synergistic interactions between these interconnected ecosystems under climate change, highlighting their importance in carbon sequestration, ocean acidification, shoreline protection, and biodiversity conservation. We examine how cross-ecosystem fluxes of organisms, nutrients, and energy enhance resistance and recovery to climate stressors, including ocean acidification, sea level rise, and marine heat waves. Despite their critical role, these ecosystems face significant vulnerability, and their continued decline poses a direct threat to coastal resilience and ecosystem services. The review emphasizes the necessity of maintaining habitat connectivity, which is integral to species survival and ecosystem function. A comprehensive conservation strategy is proposed, advocating for a polycentric governance model to address the complexities of CSM interactions, incorporating multiple stakeholders to promote sustainable management and policy coordination. Critical research gaps are identified, particularly in understanding the underappreciated role of seagrasses in marine conservation and the poorly understood spillover effects between CSM ecosystems. The study calls for a unified, evidence-based approach to coastal management that enhances the resilience of CSM ecosystems, mitigates climate impacts, and ensures the long-term sustainability of these invaluable systems for future generations.

Plankton communities underpin marine ecosystem functioning, yet the mechanisms driving the onset and termination of spring phytoplankton blooms are not fully understood. In particular, the role of microzooplankton grazing and the impact of mixotrophic versus heterotrophic ciliates on phytoplankton dynamics. This study aimed to quantify ciliate grazing and phytoplankton growth rates throughout a spring bloom in Roskilde Fjord, Denmark; and determine whether nutrient depletion or microzooplankton grazing was the primary driver of bloom culmination. Surface water was collected during March 2017, and multiple dilution experiments were conducted to estimate phytoplankton growth and grazing mortality rates. Phytoplankton community structure was assessed by flow cytometry, while ciliate morphotypes and nutritional modes were identified using FlowCam imaging. Despite initially high nutrient concentrations, a marked decrease in DIN and DIP occurred over the study period. Phytoplankton biomass, dominated by cryptophytes, reached its peak by mid-March before declining. Concurrently, ciliate assemblages shifted from mixotrophic to heterotrophic dominance. Grazing rates frequently exceeded phytoplankton growth rates after the first experimental day, indicating strong top-down control. The lack of significant differences in growth between nutrient-amended and unamended treatments suggested grazing, rather than nutrient depletion, predominantly constrained phytoplankton accumulation. These findings highlight how ciliate grazing can exert a critical influence on spring bloom dynamics, even under moderate nutrient conditions. Understanding these trophic interactions is essential for predicting the resilience and stability of coastal marine ecosystems in the face of changing environmental conditions.

It has been become increasingly clear that swimming performance is crucial for the migratory success of wild Atlantic salmon (Salmo salar) smolts, yet the associated traits remain largely unexplored. In this study, smolts were caught during their downstream migration to the sea and were categorized as strong or poor swimmers based on their time to fatigue in a swimming test. Behavioral profiles were characterized through a confinement and novelty test, and relationships to cardiac morphology and glucocorticoid profiles were investigated. Strong swimmers increased activity over time in the confinement test, while poor swimmers showed the opposite trend, indicating differences in boldness. There were no differences in plasma cortisol in groups of fish with contrasting swimming performance. Still, strong swimmers had higher cortisone levels 24 h after the swim test, suggesting a protective mechanism against elevated cortisol in this group. No differences in heart morphology were found between the groups. In addition, acoustic telemetry revealed a trend toward lower survival rates for strong swimmers in predator-rich environments. Overall, our results highlight a link between glucocorticoid profiles, boldness and swimming capacity in Atlantic salmon smolts. Further studies are needed to confirm the observed survival patterns and to better understand how predator pressure may shape the fitness consequences of these traits in migrating smolts.

We present a genome assembly from a specimen of Thunnus thynnus (Atlantic Bluefin Tuna; Chordata; Actinopteri; Scombriformes; Scombridae). The genome sequence has a total length of 799.05 megabases. Most of the assembly (99.17%) is scaffolded into 24 chromosomal pseudomolecules. The mitochondrial genome has also been assembled, with a length of 16.53 kilobases. Gene annotation of this assembly on Ensembl identified 23,266 protein-coding genes.

Lumpfish (Cyclopterus lumpus) are frequently used as “cleaner fish” to control parasitic sea lice in salmonid fish farms, but it has been questioned whether the benefits in terms of sea louse control outweigh the economic and lumpfish-welfare costs involved. Here we estimated the efficacy of lumpfish in controlling salmon lice (Lepeophtheirus salmonis) in salmonid farms by combining analyses of occurrence of salmon lice in stomach contents of lumpfish and experimental results on digestion time. We then conducted scenario simulations of salmon louse dynamics in salmonid fish farms, by combining the lumpfish feeding model with a lumpfish growth model and a salmon louse population model. Results showed that at a mean lumpfish weight of 50 g and typical conditions for other factors (9 °C, 2 kg salmonids, and 0.8 pre-adult and adult salmon lice per salmonid), the estimated feeding rate was 0.17 salmon lice per lumpfish per day (95 % confidence interval: 0.12–0.22). This rate increased with salmon louse concentration, temperature and salmonid weight and decreased with lumpfish weight. Scenario simulations of salmon louse dynamics under conditions representative for salmonid farms in Norway suggested that stocking lumpfish from the start of the production cycle with a 1:10 lumpfish per salmon ratio on average postponed the first salmon louse treatment by 43 days. The longest postponement was at intermediate external infestation pressure. Scenario simulations for a network of farms suggested that coordinated and strategic use of lumpfish after a spring treatment may succeed in supressing salmon louse outbreaks through spring and summer.

Cyanobacteria play a critical role in regulating carbon, nitrogen, and phosphorus cycles in the Baltic Sea, seasonally forming extensive blooms under nitrogen-limited conditions in summer. Understanding their responses to environmental disturbances is crucial in the Baltic Sea where increasing and persistent surface water temperature anomalies were observed over the past two decades. During a 17-day mesocosm experiment in the southwestern Finnish archipelago (Gulf of Finland) designed to investigate microbial community dynamics under varying nutrient conditions, the unexpected occurrence of a natural disturbance event created a unique opportunity to assess the effects of pronounced physical changes on cyanobacterial dynamics. The natural disturbance overshadowed the expected effects of the nutrient treatments, which was especially evident for cyanobacteria. The picocyanobacterium Cyanobium spp. emerged as the dominant species throughout the study, particularly following the occurrence of the near gale wind-driven rainfall, likely due to its adaptability to rapid environmental changes. Conversely, the filamentous cyanobacteria Aphanizomenon spp. and Pseudoanabaena spp. thrived under stable conditions. These findings highlight the resilience of picocyanobacteria to environmental fluctuations and their primary role in driving cyanobacterial community dynamics during summer in the Baltic Sea, where natural perturbations are expected to occur with increasing frequency due to climate change.

We have generated a high-quality reference genome for Anisus vorticulus to support monitoring of the genetic diversity of populations of this declining freshwater species. The chromosome-level genome assembly encompasses 1.04 Gb, composed of 835 contigs and 77 scaffolds, with contig and scaffold N50 values of 2.35 Mb and 59.2 Mb, respectively. The genome was assembled into 18 chromosomal pseudomolecules.

Flåtten øker i antall, sprer seg til nye områder, nye flåttarter ankommer landet, og stadig flere mennesker og dyr opplever flåttbitt og sykdom. Samtidig svekkes kunnskapsgrunnlaget vårt. Forskningen på flåtten er ikke bare på et minimum, men er i ferd med å tørke ut.

The Greater Oslofjord, like many other coastal systems, is undergoing rapid ecological shifts driven by climate change, coastal freshening and darkening. To understand how these bottom-up stressors restructure food webs, we utilized a multi-trophic approach analyzing three sympatric predators (approx. 500 individuals): Harbour seals (Phoca vitulina), Great Cormorants (Phalacrocorax carbo), and Atlantic Cod (Gadus morhua). We combined dietary DNA (dDNA) metabarcoding with stable isotope analysis (δ13C, δ15N) to trace temporal and spatial dietary changes over 20 years. Traditional morphological methods often fail to capture soft-bodied prey and secondary consumption; thus, we used dDNA combined with novel reference databases to maximize taxonomic resolution. Our dDNA results revealed high-resolution predation data, including the detection of secondary consumption (zoo- and phytoplankton) alongside primary prey, effectively mapping the food web from top predators down to primary producers. Isotope data complemented this by delineating trophic niche widths and source of primary production (land vs. sea). We observed distinct dietary variations linking predator foraging behavior to environmental gradients. This included observable changes over the last 20 years, such as an increase in invasive species in their diet and a shift in zoo- and phytoplankton composition. These findings demonstrate that combining molecular and isotopic analysis of top predators provides a powerful tool for monitoring the cascading effects of anthropogenic changes on marine food webs.

I en tid med svekket tillit til forskning og raske teknologiske endringer har naturfaget en nøkkelrolle i å utdanne aktive demokratiske borgere. Faget handler ikke bare om å formidle fagkunnskap, men også om å lære vitenskapelige og teknologiske praksiser og forstå naturvitenskapens egenart. Slike ferdigheter styrker elevenes evne til kritisk tenkning, vurdering av informasjon og deltakelse i sosiovitenskapelige diskusjoner. Utfordringen er at naturfagundervisningen bygger på en tradisjon som ofte vektlegger teorier og begreper fremfor praksiser (Ødegaard et al., 2021), og som kan oppleves ekskluderende for enkelte grupper (Palmer et al., 2024). For å styrke den demokratiske dannelsen i form av både kunnskap, ferdigheter og holdninger, trengs en mer praktisk og humanistisk naturfagundervisning, der naturvitenskapene forstås som en menneskelig aktivitet med egen kultur, verdier og metoder (Southerland & Settlage, 2022). En humanistisk naturfagundervisning er mer et verb enn et substantiv, og legger vekt på at kunnskap bør læres i kontekst og med utgangspunkt i et reelt behov for å vite (Klopfer & Aikenhead, 2022). Med dette som bakgrunn har vi utviklet UTFORSK-verktøyet: 12 sekskantede brikker som representerer sentrale ferdigheter i naturvitenskapelige praksiser. Gjennom designbasert forskning har vi identifisert tre prinsipper: verktøyet er fleksibelt og dynamisk, inviterer til aktiv læring og støtter lærere i arbeidet med praksiser og tenkemåter. Det gir rom for dialog fremfor endelige svar, noe som bidrar til å humanisere vitenskapen. Brikkene hjelper lærere med planlegging, fokusering og refleksjon, og legger til rette for læringsprosesser som engasjerer elever i konkrete fenomener og diskusjoner om formål, verdier og metoder.

Det er et uttalt mål å øke den nasjonale selvforsyningsgraden. Men fiskeri var knapt nevnt når regjeringen lanserte totalberedskapsplan. Det mangler en nasjonal plan for hvordan norsk fisk og skalldyr skal gjøres tilgjengelig i en krise, og hvordan fiskeflåten faktisk kan være beredt.

Havkunnskap er knapt nevnt i læreplanen, selv om Norge er en havnasjon, påpeker Nasjonalkomiteen for FNs havforskningstiår. De ber om at havet løftes høyere i skolen fra tidlig alder.

Bruk av KI kan svekke læring, lesing og faglig selvtillit hos bioingeniørstudenter, advarer foreleser Vivian Kjelland. Hun mener egen tenking og faktakunnskap er avgjørende for trygghet, eksamen og pasientsikkerhet.

Det finnes mange myter om flåtten. Forsker Vivian Kjelland er redd desinformasjonen kan øke smitten av flåttbårne sykdommer.

Mange firbente bærer på skjult smitte etter flåttbitt. Slik avslører du de usynlige symptomene, og unngår den vanligste miljøfellen når du behandler kjæledyret ditt.

Vi husker fra historietimene at Svartedauden kom med et skip til Bjørgvin i 1349. Hva var Svartedauden, og er denne bakterien fortsatt aktuell for en ny pandemi? I denne episoden har vi besøk av Nils Chr. Stenseth, som er professor i biologi og nestleder ved Senter for pandemi- og én-helseforskning ved Universitetet i Oslo. Stenseth har i en årrekke forsket på hvordan bakterien som forårsaket svartedauen - yersinia pestis – har beveget seg rundt i verden. Han har også forsket på hvordan klima kan påvirke både denne bakterien og hantavirus, for eksempel. I studio ellers er som vanlig overlege Frank Olav Pettersen fra Infeksjonsmedisinsk avdeling ved Ullevål, og Gunnveig Grødeland som er professor i immunologi og leder for Senter for pandemi- og en-helseforskning ved Universitetet i Oslo.

Fuktig vårvær og varme har gitt myggen perfekte forhold, og været fremover vil avgjøre hvor ille det kan bli.

Mange kjæledyr får mye blodsugende flått på seg.

Mildere klima gir økt risiko for at flåtten kan etablere seg fast i Finnmark.

I denne parallellsesjonen ønsker jeg å dele erfaringer med bruk av papirkretser som et verktøy for å fremme kreativitet, problemløsning og estetiske læringsprosesser i naturfag. Gjennom arbeidet med papirkretser får studentene mulighet til å kombinere praktisk arbeid med kunstnerisk uttrykk og teknologisk forståelse – en tilnærming som kan beskrives som educative making. Undervisningsopplegget jeg presenterer, er utviklet for lærerutdanning i naturfag, og har som mål å vise hvordan praktisk arbeid kan være både deduktivt og induktivt. Studentene introduseres først for grunnleggende prinsipper for elektriske kretser gjennom en strukturert, deduktiv øvelse med en ferdig mal. Deretter får de bruke det de har lært til å lage egne kreative produkter – ofte med estetiske og personlige uttrykk – hvor de må anvende kunnskapen på nye måter. Dette gir rom for utforskning, feiling og problemløsning, og åpner for refleksjon rundt hvordan praktisk arbeid kan bidra til dypere forståelse i naturfag. Når den kreative aktiviteten gjennomføres som gruppearbeid, gir det også en mulighet til å rette oppmerksomheten mot sosiale, kulturelle og politiske krefter i læringsmiljøet. Ved å be studentene reflektere individuelt over hvordan deres posisjon i gruppa påvirket prosessen og resultatet, kan man åpne for viktige samtaler om makt, inkludering og deltakelse i undervisning og læring. Som inspirasjon viser jeg også til prosjektet Illuminated Masterpieces fra en videregående skole i USA, hvor elever har laget kunstverk med integrerte papirkretser i kunstfaget. Dette prosjektet illustrerer hvordan kunst og ingeniørtenkning kan møtes i undervisningen, og hvordan estetiske prosesser kan styrke elevenes engasjement og læring i naturfag.

The latest educational reform in Norway in 2020 has raised new challenges for science teachers and teacher educators. This presentation will focus on providing insight into our response to two of the curricula changes 1) the introduction of the core element Natural science practices and approaches and 2) that teachers at the secondary level in Norway are now required to integrate computer programming into their science teaching. I will argue that although these new elements are well supported and justified by changing societal demands and aligned with educational reforms worldwide, they are ambitious and present significant challenges regarding preservice and in-service teachers' competence and teacher identities. There is a need for systematic educational research supporting implementation processes in the context of teacher education and in schools. I will present parts of our published and ongoing research regarding how to understand and implement the core element Natural science practices and approaches as well as a study investigating the positioning of preservice teachers regarding the incorporation of programming in mathematics and science education (in process). Both directions of the research I will present envision preservice and in-service teachers as change agents and focus on how to empower teachers in implementing science teaching aligned with the new curriculum, recognizing tensions and viewing teachers as resources rather than from a deficit perspective.

Fremtidens bioingeniørutdanning og harmonisering av utdanningene i Europa var hovedtemaer for utdanningskonferansen i Bergen.

Det er ikke så farlig om studentene spiser for mye pizza og har det rotete hjemme. Det er viktigere at de har noen gode studievaner. Her er noen triks foreldre kan bidra med.

Abandoned, lost and discarded fishing gear (ALDFG) contributes to marine littering and can continue to capture animals after they have been lost resulting in what is called ghost fishing. Ghost fishing is a global problem and poses a threat in several ways. It negatively affects targeted and non-target species, marine habitats, ecosystems and fisheries sustainability. The issue of ghost fishing has gained more recognition over the years, hoverer, information on its many impacts regarding the environment, species and habitats is still lacking. Norway have implemented legislations to try and reduce ghost fishing, for instance, having a cotton thread in fishing gear. The thread is designed to degrade after a given amount of time in the water making is easier for trapped animals to escape. The Institute of Marine Research in Norway and Green bay AS started a clean-up project to remove ghost gear in Raet national park in 2019. In 2021 the project expanded to other national parks, and it is still ongoing. This thesis used data collected in this project from 2019-2024 to investigate several aspects of ghost fishing along the Norwegian coast; catchability over time, breakdown time of the cotton thread, regional differences and what depths animals was ghost fished at. Catchability decreased the longer a trap had been in the ocean, regarding parlour traps and brown crab, and it decreased significantly faster in traps with cotton thread. The probability of the cotton thread dissolving passed the 50% mark at 130 days after gear loss. Results from regional differences showed that there were higher catches of brown crab in the southeast and a higher number of crayfish traps and CPUE of wrasse in the west. Different species were mainly caught in ghost gear at depths where they are usually found. These results highlight the importance of the cotton thread and provide useful insight into how to better regulate ghost fishing in both regions in Norway. As ghost gear still poses as a threat to the marine environment, more research on the subject and arranging more clen-up projects is recommended.

Eelgrass meadows are key coastal habitats that provide critical ecosystem services. In Nordic coastal waters, these ecosystems are increasingly exposed to multiple stressors, and one of the emerging symptoms of ecological change is the proliferation of ephemeral algae, locally referred to as lurv. Ephemeral algae are short-lived communities of filamentous algae, benthic diatoms, and cyanobacteria, and high abundances have been associated with degradation of seagrass and kelp habitats. This study investigates the seasonal dynamics of ephemeral algae within eelgrass meadows in southern Norway, with a particular focus on understanding how environmental factors influence changes in ephemeral epiphytic and drift algae abundance, cover, structure and species composition throughout the season. Fieldwork was conducted using underwater video transects combined with algal sampling and environmental measurements. Video footage was analyzed to quantify algae occurrence and cover. While algal samples were used to assess the composition of the algal assemblages The results show clear seasonal variation in ephemeral algae, both in abundance and community composition. Epiphytic algae appeared to dominate early in the season, while filamentous algal forms became more prominent later in the summer and autumn. Algal cover and structure also varied between stations, suggesting that local environmental conditions influence both the development and persistence of ephemeral algae within eelgrass meadows. These findings contribute to a better understanding of how ephemeral algae develop and vary across season and space. They also highlight the importance of considering seasonal timing and local environmental conditions when assessing algal pressure in eelgrass habitats. Such knowledge is essential for developing a deeper understanding of ephemeral algae and eelgrass interactions in Skagerrak’s coastal ecosystems and for supporting management strategies aimed at sustaining seagrass ecosystems under increasing anthropogenic pressure.

Marine biodiversity is increasingly being lost as coastal urbanization accelerates and artificial marine structures expand globally. Following an increased awareness of the potential ecological risks and benefits of this development, there is a growing interest in enhancing biotic colonization on these structures. This study investigated colonization on newly introduced hard substrates in a temperate marine environment in southern Norway. Concrete plates (n = 54) of two types, conventional Portland cement concrete (B45) and a lower carbon fly ash alternative (B20) with diƯerent surface structure (smooth, normal and rough), were deployed at 1.5 metres depth at four diƯerent study sites in Lindesnes and Kristiansand municipalities. Additionally, three diƯerent rock types (rhomb porphyry, larvikite and trachyte) were deployed at the same sites. After an 11-month submersion period, the plates were retrieved and community composition, species richness and Shannon diversity were assessed. A total of 58 unique taxa were observed in this study and all plates, regardless of material, were successfully colonized in the duration of the study. The results showed that site was consistently the most dominant factor in explaining variation in species communities. On concrete plates, site explained 32 - 37% of variation in community composition while neither concrete type nor surface structure had a significant eƯect. A similar pattern was observed on rock plates, with site explaining 35 - 39% of variation. NMDS ordination indicated a clear separation in community composition between Lindesnes and Kristiansand. No significant eƯect from concrete type, surface structure or rock type was observed on species richness or Shannon diversity. In conclusion, this study indicates that environmental site-specific factors, light availability and hydrodynamic conditions in particular, play a more important role than substrate properties in determining biotic colonization. Although relatively low replication and subtle structural diƯerences between substrates are noted as limiting factors, this study indicates that location, rather than substrate, may be more important in determining the ecological eƯects of facilitating colonization.

Turf algae blooms are an increasing environmental concern in coastal ecosystems, as they are leading to a uniform landscape dominated by turf, habitat loss, and thus lower biodiversity. In addition, heavy metal pollution and organotin compounds in the marine environment may pose harmful effects on marine organisms, ecosystems, and human health. Turf algae have also been suggested as a potential resource for agricultural fertilizers, making it important to consider their capacity for accumulation of pollutants. The aim of this study was to investigate the extent to which turf algae accumulate metals and organotin compounds, and whether spatial and seasonal variations influence contamination levels. Turf samples were collected from three locations along the southern coast of Norway, with three stations sampled at each location. Two of the locations were sampled during both spring and autumn. Chemical analyses were conducted by an accredited laboratory, while statistical analyses, including PCA biplots, were performed in RStudio. Overall, the results showed relatively low concentrations of metals and organotin compounds across most stations, with the exception of one marina station that appeared to represent a localized contamination hotspot. The marina stations generally contained the highest concentrations of both metals and organotin compounds, whereas the one location without a marina displayed the lowest overall contamination levels. The heavy metal concentrations were generally higher during autumn compared to spring. PCA analyses further indicated associations between certain metals and specific stations and seasons. The findings show that turf algae accumulate both metals and organotin compounds to levels that could limit their suitability for agricultural applications such as fertilizer. However, the ability of turf algae to accumulate contaminants may also indicate a potential role in the removal of pollution from contaminated coastal environments.

The vast majority of marine fish are ectotherms, meaning their body temperature closely tracks that of the surrounding water, making them highly sensitive to changes in ambient temperature both physiologically and behaviourally. With ongoing climate change driving ocean warming, understanding how fish respond behaviourally to shifting thermal conditions is increasingly important for predicting ecological consequences at the population level. This study examined seasonal and diel variation in depth use by acoustically tagged Atlantic cod (Gadus morhua) in and around Raet National Park (607 km²) on the Norwegian Skagerrak coast, over one annual cycle (October 2023 – October 2024), using detections from 81 acoustic receivers distributed across a large, open coastal system that includes both nearshore and offshore habitats. A total of 26 individuals were retained for analysis after filtering. Generalised additive mixed models were fitted to mean daily depth of these fish, with day of year, sea surface temperature, and diel period as predictors, and individual identity as a random effect. Cod occupied greater depths during summer, when sea surface temperatures were highest, and shallower depths during the remaining seasons. Sea surface temperature exerted a significant independent effect on depth use beyond the seasonal trend. Diel vertical migration was consistent across the year, with cod on average occupying depths approximately 9% shallower at night than during the day. Individual cod differed substantially in their depth use throughout the year, reflecting pronounced among-individual variation in habitat use that persisted beyond what was explained by season, temperature, or time of day. These findings are consistent with depth use patterns previously reported from telemetry studies conducted in smaller, more confined inshore areas along the same coastline, showing that similar seasonal and diel behavioural signals are detectable across a much larger and more open study system. As ocean temperatures continue to rise, the association between warm surface conditions and the cod’s use of deeper habitats suggests that thermally driven displacement from shallow coastal foraging habitats may intensify, with potential consequences for the productivity and recovery of coastal cod populations in Skagerrak.

Seagrasses are a group of highly productive marine angiosperms and provide many ecosystem services, such as habitat provisioning, sediment stabilization and carbon sequestration. Seagrasses are in decline globally, which has been attributed to anthropogenic disturbance and climate change. The Skagerrak has in recent times been affected by coastal darkening and more frequent marine heatwaves, which will likely worsen under global warming. This experiment examined the concurrent effects of temperature increase and nutrient enrichment on eelgrass (Zostera marina), which is the dominant seagrass species along the Skagerrak coast. Using eelgrass transplanted from a local sheltered meadow, we manipulated nutrient levels and temperature in a full factorial outdoor mesocosm experiment. The experiment ran for eight weeks from mid-July to mid-September 2024, exposing eelgrass to four treatment combinations: ambient, warming (+3 °C), nutrient enrichment (one week pulse) and warming + enrichment. Maximum quantum yields were assessed using pulse-amplitude-modulation fluorometry, and morphometrics were taken before and after the experiment. An incidental two-week natural heatwave occurred during the experimental period, pushing temperatures in the heated treatment up to ~28°C. Treatments had mainly positive effects on seagrass growth metrics and maximum quantum yield, however with low overall significance. The experiment allowed for natural colonization of invertebrate fauna, and a thesis parallel to this one found significant effects on associated fauna. Our synthesis is therefore that eelgrass and associated fauna should be considered together when analyzing anthropogenic impacts on seagrasses. Our results suggest that eelgrass itself exhibits resilience to thermal stress with concurrent enrichment, however associated faunal biodiversity could be more strongly affected with potential consequences for ecosystem functioning.

Denne studien ser på hvordan lyr bruker områder, dybde og temperatur gjennom året og mellom dag og natt i Raet nasjonalpark i Skagerrak. Lyr er en viktig art både økologisk og kommersielt, men vi vet fortsatt ganske lite om hvordan den faktisk bruker habitatet sitt i norske havområder, spesielt når det gjelder bruk av temperatur og dybde. Ved bruk av akustisk telemetri ble data fra 43 merkede individer (34 – 63 cm lengde) samlet inn i perioden 2023 – 2025, i form av deteksjoner av individuelle fisk i et nettverk av utplasserte mottaker-stasjoner. Deteksjons-datae ble brukt til å analysere variasjon i bruk av dybde og temperatur. I tillegg ble det undersøkt hvor lenge de forskjellige fiskene oppholdt seg i nærheten av de forskjellige mottakerene for å se om områdebruken endret seg gjennom året. Resultatene viser klare sesongforskjeller. Lyr oppholdt seg generelt i dypere og kaldere vann gjennom vinteren og våren, mens den brukte grunnere og varmere vann om sommeren og høsten. Det var også forskjeller mellom dag og natt, men disse var relativt små. I tillegg var det tydelige individuelle forskjeller mellom fiskene, noe som forklarte en betydelig del av variasjonen i både dybde- og temperaturbruk. Arealbruken var mer konsentrert om vinteren og mer spredt om sommeren. Samlet sett tyder resultatene på at temperatur spiller en viktig rolle for hvordan lyr bruker habitatet sitt. Studien viser at både sesong og individuelle forskjeller bør tas med i vurderingen når arten skal forvaltes. Dette er relevant for videre utvikling av tiltak i marine verneområder.

Nocturnal migration is a common strategy among anadromous brown trout (Salmo trutta) during migration. This strategy reduced detection by visually oriented predators, thereby increasing survival during migration. Additionally, nocturnal migration reduces the need to engage in antipredator behaviour observed in diurnally migrating smolts, thereby minimizing the allocation of time and energy away from migration. Artificial light at night threatens nocturnal migration by altering the ecological condition that facilitate this strategy. In this study, we compared passage times over a defined stream section for nocturnally migrating brown trout in two coastal streams in the south of Norway under natural darkness and under artificial illumination from a LED lighting (mean light intensity at the stream bed ≈ 60 lux). Nocturnally migrating brown trout exhibited significantly longer passage times under illuminated conditions than during control nights (p = 0,0004), exceeding passage times observed during the day. In this study, spatial analyses were also conducted to assess the extent to which anadromous streams are rivers were affected by artificial light from streetlights within the costal municipalities in Agder County, southern Norway. The analyses revealed that high-intensity exposure occurred in 32% of streams, while 14% were exposed only to low intensities. However, low intensity exposure was three times more spatially extensive. Additionally, all of the anadromous rivers were exposed to artificial light, although exposure was primarily localized to riverbeds adjacent to settlements and at bridge crossings.

Understanding seabirds spatial use across seasons is essential for evaluating their ecological strategies and potential interactions with human activities like landfills and fisheries. This thesis combines GPS tracking of breeding great black-backed gulls (Larus marinus) in Tvedestrand on the Norwegian Skagerrak coast and vessel monitoring system (VMS) data to investigate spatial behaviour during the breeding season and fall period, and any overlap of individual movement behaviour with fishing vessels tracked within the Skagerrak region during the years 2024 and 2025. This study shows clear seasonal differences in spatial behaviour, with restricted movements, small core areas (0.7 - 5.8 km2) consistent with central place foraging theory, and minimal overlap with fishing activity during the breeding season (0 - 20%). The kernel density utilization distribution expanded by three orders of magnitude during the fall period (1,292 - 4,142 km2) with markedly higher overlap with fishing activity (34 - 56%). Despite these seasonal shifts, individuals showed consistent behavioural differences across periods and showed strong site fidelity, repeatedly using similar areas and movement routes across years. Overlap with fisheries varied among individuals, indicating individually specialized strategies in foraging behaviour connected to anthropogenic resources. These results suggest that individual tactics may result in inter-individual differences in vulnerability to the impact of fisheries. Future studies attempting to address the impact of fisheries on seabird populations would benefit from investigating potential links among non-breeding movements, overlap with fisheries and breeding efforts. In conclusion, this thesis highlights the importance of tracking individual tactics in spatial use over time, as individual specialisation seems to be the source of both population width and overlap with fisheries.

Partial migration, where some individuals migrate while others remain resident, is a widespread life-history phenomenon in brown trout (Salmo trutta). The factors driving individual migration decisions remain incompletely understood, particularly in small coastal streams. This study investigated partial migration in juvenile brown trout across three small coastal streams in Agder, Southern Norway, combining PIT-tag telemetry, molecular sex determination, behavioral boldness and environmental monitoring. A total of 418 juvenile trout were tagged in spring 2025 and monitored throughout the spring migration period (April - June). Migration probability was modelled using a generalized additive mixed model (GAMM), and migration timing was analyzed with a mixed-effects Cox proportional hazards model. Across all streams, 63.9 % of tagged individuals were classified as migrants, indicating that anadromy was the predominant strategy. Migration probability was strongly sex-biased, with females migrating at substantially higher rates than males, and body length showed a sex-specific, non-linear effect. Migration timing was driven by daily water temperature and body condition (Fulton's K), where individuals were more likely to migrate during periods of warmer water, and better-conditioned individuals migrated later in the season. Boldness did not predict either migration probability or timing, and no sex difference in boldness was detected. These findings demonstrate that partial migration in juvenile brown trout from small coastal streams is shaped primarily by sex, body length and water temperature, with sex-specific life-history trade-offs producing different relationships between body size and migration tactic in males and females. The results highlight the value of combining molecular sex determination with individual telemetry to capture true population-level migration patterns.

Verdens befolkning forventes å nærme seg 10 milliarder innen 2050, noe som øker behovet for bærekraftig matproduksjon. Akvakultur er den raskest voksende matproduksjonssektoren globalt, og landbaserte resirkulerende akvakultursystemer (RAS) trekkes frem som en teknologi med potensial til både å redusere miljøpåvirkningen fra fiskeoppdrett og muliggjøre effektiv og kontrollert produksjon av fisk. Samtidig produserer slike systemer betydelige mengder næringsrikt avløpsvann som inneholder blant annet nitrogen og fosfor, og som i dag i stor grad slippes ut uten videre ressursutnyttelse. Denne avhandlingen evaluerer potensialet for å integrere dyrking av marine mikroalger i avløpsvann fra et modulært resirkulerende akvakultursystem (MRAS) for Atlantisk laks. Mikroalgenes vekst, næringsopptak, og biomasseproduksjon blir kvantifisert gjennom en 14 dagers vekstperiode i ulike konsentrasjoner avløpsvann fra M-RAS. Bakteriesamfunnets sammensetning i produksjons- og avløpsvann i M-RAS gjennom en full produksjonssyklus på 44 uker blir også undersøkt, i tillegg til bakteriesamfunn i algekulturer dyrket på dette avløpsvannet. Tre arter ble studert: Phaeodactylum tricornutum, Isochrysis galbana og Skeletonema marinoi. Alle tre mikroalgeartene viste stabil vekst i ubehandlet M-RAS-avløpsvann ved ulike fortynningsgrader. Under disse forholdene ble uorganiske næringssalter effektivt fjernet fra vannet, med nær fullstendig reduksjon av nitrat, nitritt og fosfat, og omtrent 90 % reduksjon av ammonium. Avløpsvann fra M-RAS kan dermed fungere som et næringsrikt vekstmedium for mikroalger. Phaeodactylum tricornutum utmerket seg med høy fosforutnyttelse og god biomasseproduksjon. Innholdet av langkjedede omega-3-fettsyrer i biomassen var imidlertid relativt lavt, noe som indikerer at videre optimalisering av dyrkingsforhold er nødvendig dersom målet er produksjon av høykvalitets fôrkomponenter. Resultatene viste at bakteriesamfunnene i M-RAS gjennomgikk en tydelig omstrukturering i den tidlige fasen av produksjonssyklusen, etterfulgt av en mer stabil sammensetning senere i produksjonen. Samtidig ble det observert episodiske topper hos enkelte bakteriegrupper, noe som indikerer en respons på endringer i både driftsforhold og næringstilgang i systemet. I algekulturer dyrket på M-RAS-avløpsvann utviklet det seg distinkte bakteriesammensetninger, noe som viser hvordan bakteriesamfunn fra oppdrettssystemet kan påvirke mikrobielle prosesser i dyrkingssystemer basert på avløpsvann. Denne studien demonstrerer potensialet for å koble mikroalgedyrking til næringsgjenvinning i landbaserte oppdrettssystemer. Samtidig viser resultatene at bakterielle prosesser i både RAS og algekulturer kan påvirke hvordan slike integrerte systemer fungerer. Resultatene bidrar derfor med ny kunnskap om biologiske prosesser som må forstås og håndteres dersom mikroalger skal inngå i fremtidige sirkulære løsning for landbasert akvakultur.

Eelgrass meadows are biogenic habitats and important coastal ecosystems that grow along the entire Norwegian coast and serve important ecological functions. Eelgrass meadows provide habitat for diverse communities of invertebrate fauna above and below the sediment which are integral to ecosystem functioning. These communities are impacted by several natural and anthropogenic drivers. Changes in the composition of faunal communities have been linked to declining eelgrass meadows in the West of Sweden, but the faunal composition of Norwegian eelgrass is relatively understudied. In autumn 2002 (Fredriksen et al., 2010) sampled infaunal communities in eelgrass meadows and adjacent bare sediment in outside Flødevigen research station in the south of Norway. In 2023 the sites outside Flødevigen were resampled in summer and autumn to study changes in the faunal communities between 2002 and 2023, and between seasons in 2023. Taxonomic and functional compositions were compared with PERMANOVA and visualized using NMDS plots, changes in density were compared with GLMs and changes in diversity and functional indices were compared with ANOVA using sampling occasion (year and season), site and habitat type (vegetated and bare sediment) as factors. Density, species richness, and Shannon diversity decreased both from 2023 to 2002 and from summer to autumn in 2023. In both cases, taxonomic composition changed, whereas functional composition did not change significantly. The observed changes in density and diversity could be linked to changes in environmental factors such as eutrophication and temperature, as well as natural variability in infaunal communities. Based on this study, it is recommended that future monitoring of infauna in eelgrass continue with more frequent sampling at regular intervals at multiple sites to be able to distinguish general tendencies in infaunal communities from natural variation. The faunal community composition and ecosystem processes in eelgrass are closely linked, which is why these communities need to be considered in the monitoring of the ecological condition of eelgrass.