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Improving coral monitoring by reducing variability and bias in cover estimates from seabed images
Get PDFSeabed cover of organisms is an established metric for assessing the status of many vulnerable marine ecosystems. When deriving cover estimates from seafloor imagery, a source of uncertainty in capturing the true distribution of organisms is introduced by the inherent variability and bias of the annotation method used to extract ecological data. We investigated variability and bias in two common annotation methods for estimating organism cover, and the role of size selectivity in this variability. Eleven annotators estimated sparse cold-water coral cover in the same 96 images with both grid-based and manual segmentation annotation methods. The standard deviation between annotators was three times greater in the grid-based method compared to segmentation, and grid-based estimates from annotators tended to overestimate coral cover. Size selectivity biased the manual segmentation; the minimum size of colonies segmented varied between annotators fivefold. Two modelling techniques (based on Richard’s selection curves and Gaussian processes) were used to impute areas where annotators identified colonies too small for segmentation. By imputing small coral sizes in segmentation estimates, the coefficient of variation between annotators was reduced by approximately 10%, and method bias (compared to a reference dataset) was reduced by up to 23%. Therefore, for sparse, low cover organisms, manual segmentation of images is recommended to minimise annotator variability and bias. Uncertainty in cover estimates may be further reduced by addressing size selectivity bias when annotating small organisms in images using a data-driven modelling technique.publishedVersio
Integration of citizen science and eDNA reveals novel ecological insights for marine fish conservation
Get PDFIn the face of climate change, the accelerating nature crisis, and other anthropogenic impacts, conserving biodiversity demands effective monitoring. While innovative approaches have emerged to enhance biodiversity assessment, significant data gaps persist, particularly within marine ecosystems. In this study, we assess the utility of combining citizen (community) science with environmental DNA (eDNA) metabarcoding for characterizing and quantifying marine fish biodiversity. Over the summer of 2022, 32 volunteers conducted extensive water sampling in a large Norwegian fjord, yielding 96 samples. Contrasting eDNA findings with conventional observational surveys (such as a national species registration database and beach seine surveys) unveiled a substantial overlap in recorded species inventories. The eDNA citizen science initiative identified previously undocumented species and rediscovered others emphasizing an increase in warm-water species within the study area. Additionally, eDNA data unveiled reduced diversity within the inner fjord relative to the outer fjord. To conclude, our study demonstrates the successful integration of eDNA within a citizen science framework, facilitating comprehensive biodiversity tracking across coastal marine regions. These findings hold promise for advancing marine conservation efforts by providing valuable data to inform critical decision-making processes.publishedVersio
Uncrewed surface vehicles (USVs) as platforms for fisheries and plankton acoustics
Get PDFUncrewed surface vehicles (USVs) equipped with echosounders have the potential to replace or enhance acoustic observations from conventional research vessels (RVs), increase spatial and temporal coverage, and reduce cost and carbon emission. We discuss the objectives, system requirements, infrastructure, and regulations for using USVs with echosounders to conduct ecological experiments, acoustic-trawl surveys, and long-term monitoring. We present four example applications of USVs with lengths <8 m, and highlight some advantages and disadvantages relative to RV-based data acquisitions. Sail-driven USVs operate continuously for months and are more mature than motorized USVs, but they are slower. To maintain the pace of an RV, multiple sail-powered USVs sample in coordination. In comparison, motorized USVs can travel as fast as RVs and therefore may facilitate a combined survey, interleaving USV and RV transects, with RV-based biological sampling. Important considerations for all USVs include platform design, noise and transducer motion mitigation, communications and operations infrastructure, onboard data processing, biological sampling approach, and legal requirements. This technology is evolving and applied in multiple disciplines, but further development and institutional commitment are needed to allow USVs equipped with echosounders to become ubiquitous and useful components of a worldwide network of autonomous ocean observation platforms.Uncrewed surface vehicles (USVs) as platforms for fisheries and plankton acousticspublishedVersio
Undersøkelser av hydrokarboner og organiske miljøgifter i sedimenter fra Mareano-området i 2023
Get PDFHavforskningsinstituttet har gjennomført målinger av hydrokarboner (PAH) i sedimenter fra 14 lokaliteter i Mareano-området, inkludert syv sedimentkjerner. I overflatesedimenter ble det i tillegg målt totalt hydrokarbon innhold (THC), bromerte flammehemmere (PBDE), klorerte miljøgifter (PCB og pesticider) og ved seks lokaliteter også «nye» organiske miljøgifter (PFAS, alkylfenoler, bisfenol A (BPA), dekloraner, fosfororganiske flammehemmere (PFR), klorparafiner og siloksaner). Prøvene var innsamlet i 2023 i områdene Sørlige Nordsjø 1 (NSJ-1) og Utsira i Nordsjøen og i deler av Skagerrak. Meget lave nivåer av hydrokarboner ble funnet i grove sedimenter fra område NSJ-1, mens noe høyere nivåer ble funnet i Utsira-område og enda høyere nivåer i Skagerrak. Benzo[a]pyren og PAH16 var i Miljødirektoratets klasse I («Bakgrunn») i område NSJ-1, klasse II («God tilstand») i Utsira-område og Skagerrak, og for PAH16 i tilstandsklasse III («Moderat forurenset») ved én lokalitet i Skagerrak. PAH-konsentrasjonsprofiler i kjernene tydet for det meste på tilførsler av pyrogene PAH i moderne sedimentlag, knyttet til antropogen påvirkning. Nivåene av menneskeskapte organiske miljøgifter av alle typer listet ovenfor var relativt lave eller meget lave. Nivåene var som regel høyere i Skagerrak enn i Nordsjøen. Nivåene tilsvarte Miljødirektoratets klasse II for de stoffene som det er etablert tilstandsklasser for, med unntaket av PFOS som var i tilstandsklasse III ved to lokaliteter i Skagerrak og Utsira-område, og BPA som var i denne klassen ved én lokalitet i Skagerrak.Undersøkelser av hydrokarboner og organiske miljøgifter i sedimenter fra Mareano-området i 2023publishedVersio
The ontogeny of lymphoid organs and IgM<sup>+</sup> B-cells in ballan wrasse (Labrus bergylta) reveals a potential site for extrarenal B-cell lymphopoiesis: The pancreas
Get PDFVaccination of farmed fish is the most effective prophylactic measure against contagious diseases but requires specific knowledge on when the adaptive immune system is fully developed. The present work describes kidney and spleen morphogenesis as well as B-cell development in the ballan wrasse (Labrus bergylta). The kidney was present at hatching (0 days pot hatching, dph) but was not lymphoid before larvae was 50–60 dph (stage 5), containing abundant Igμ+ cells. The spleen anlage was first observed in larvae at 20–30 dph and was later populated with B-cells. Unexpectedly, we found strong RAG1 signal together with abundant Igμ+ and IgM + cells in the exocrine pancreas of larvae from when the kidney was lymphoid and onwards, suggesting that B-cell lymphopoiesis occurs not only in the head kidney (HK) but also in pancreatic tissue. In this agastric fish, the pancreas is diffused along the intestine and the early presence of IgM+ B-cells in pancreatic tissue might have a role in maintain immune homeostasis in the peritoneal cavity, making a substantial contribution to early protection. IgM-secreting cells in HK indicate the presence of systemic IgM at stage 5, before the first IgM+ cells were identified in mucosal sites. This work together with our previous study on T-cell development in this species indicates that although T- and B-cells start to develop around the same time, B-cells migrate to mucosal tissues ahead of T-cells. This early migration likely involves the production of natural antibodies, contributing significantly to early protection. Moreover, a diet composed of barnacle nauplii did not result in an earlier onset of B-cell lymphopoiesis, as seen in the previous study analysing T-cell development. Nevertheless, components for adaptive immunity indicating putative immunocompetence is likely achieved in early juveniles (>100 dph). Additionally, maternal transfer of IgM to the offspring is also described. These findings provide important insights into the development of the immune system in ballan wrasse and lay the foundation for optimizing prophylactic strategies in the future. Furthermore, this work adds valuable information to broaden the knowledge on the immune system in lower vertebrates.publishedVersio
Geographic redistribution of farmed salmonids reduces salmon lice infestations and treatment frequency in a simulation study
Get PDFHost density is a key driver in parasite population dynamics, and often the number of parasites increases rapidly with host density. In the context of Norwegian salmonid farming, this mechanism has led to a disparity between the desire to increase cultured salmonid production, and to reduce the negative effects of parasite infestations. Salmon lice infestations are detrimental to animal welfare due to salmon lice treatments and spillover from farms to wild salmonids. Here, we examine how a redistribution of the salmonid farm biomass may hamper exchanges of lice larvae between farms, and consequently reduce the salmon lice burdens and treatment frequencies. More specifically, we use a stochastic simulation model, fitted to empirical data from Norwegian aquaculture, to examine how lice abundances and treatments responded when the biomass in the system was distributed onto fewer, larger farms situated farther apart. To maintain realistic fish growth, seasonality and cohort development, lice population dynamics were simulated on top of historic production data from Norway. We simulated several scenarios, where an increasing number of farms were closed, and their biomass was redistributed to other farms with matching co - horts. The results indicate that fewer and larger farms reduce lice numbers and treatment frequency, and that a strategic removal of farms, based on their importance for connectivity in an oceanographic lice dispersal network, improves this effect. Some core mechanisms are highlighted that should be considered in regional production planning, and in the allocation of production concessions in salmonid farming.publishedVersio
Observing change in pelagic animals as sampling methods shift: the case of Antarctic krill
Get PDFUnderstanding and managing the response of marine ecosystems to human pressures including climate change requires reliable large-scale and multi-decadal information on the state of key populations. These populations include the pelagic animals that support ecosystem services including carbon export and fisheries. The use of research vessels to collect information using scientific nets and acoustics is being replaced with technologies such as autonomous moorings, gliders, and meta-genetics. Paradoxically, these newer methods sample pelagic populations at ever-smaller spatial scales, and ecological change might go undetected in the time needed to build up large-scale, long time series. These global-scale issues are epitomised by Antarctic krill (Euphausia superba), which is concentrated in rapidly warming areas, exports substantial quantities of carbon and supports an expanding fishery, but opinion is divided on how resilient their stocks are to climatic change. Based on a workshop of 137 krill experts we identify the challenges of observing climate change impacts with shifting sampling methods and suggest three tractable solutions. These are to: improve overlap and calibration of new with traditional methods; improve communication to harmonise, link and scale up the capacity of new but localised sampling programs; and expand opportunities from other research platforms and data sources, including the fishing industry. Contrasting evidence for both change and stability in krill stocks illustrates how the risks of false negative and false positive diagnoses of change are related to the temporal and spatial scale of sampling. Given the uncertainty about how krill are responding to rapid warming we recommend a shift towards a fishery management approach that prioritises monitoring of stock status and can adapt to variability and change.publishedVersio
Modelling seasonal and geographical n-3 polyunsaturated fatty acid contents in marine fish from the Northeast Atlantic Ocean
Get PDFDemand for n-3 polyunsaturated fatty acids (n-3 PUFAs) exceeds supply. Large-scale studies on effects of season and geography of n-3 PUFAs in marine fish from the Northeast Atlantic Ocean (NEAO) may be used to optimize utilization and improve nutrition security. Using a sinusoid model, seasonal cycles of n-3 PUFAs were determined and found to be species-specific and clearly pronounced for the pelagic zooplankton feeding species. The Greenland halibut showed very little seasonal variation. The n-3 PUFA content in North Sea autumn-spawning (NSAS) herring peaked in summer, while Norwegian spring-spawning (NSS) herring and mackerel had their peak in autumn. A time shift of peaks in n-3 PUFAs between the two herring stocks was detected, likely due to different spawning strategies in addition to a delay of n-3 PUFAs flux in the northern regions of the NEAO. This study demonstrates that consideration of nutrient contents, such as n-3 PUFAs, when organizing and structuring fishery approaches may improve overall nutritional yield. Based on total annual Norwegian fish landings and seasonal variation in n-3 PUFA contents, n-3 PUFAs yield could theoretically be increased from 13.79 kilo ton per year from the current fishing tactics, to 15.54 if the pelagic species were only caught during the time of their seasonal n-3 PUFA peaks. Pelagic fish is a good source for dietary n-3 PUFAs, but harvest timing will also influence n-3 PUFAs intake by human consumers. One portion of fatty fish harvested during winter/spring may not meet the weekly intake reference nutritional guidelines for n-3 PUFAs. Marine n-3 PUFAs yields also varied geographically and decreased southwards, with the lowest values in Skagerrak. This study can serve as a model to understand patterns of reproductive cycles and geographical distribution of n-3 PUFAs in fatty fish from the NEAO and the novel approach may be useful to support sustainable, seasonal fishing programmes for optimization of n-3 PUFAs yields.publishedVersio
Water Effective Diffusion Coefficient in Dairy Powder Calculated by Digital Image Processing and through Machine Learning Algorithms of CLSM Micrographs
Get PDFRehydration of dairy powders is a complex and essential process. A relatively new quantitative mechanism for monitoring powders’ rehydration process uses the effective diffusion coefficient. This research focused on modifying a previously used labor-intensive method that will be able to automatically measure the real-time water diffusion coefficient in dairy powders based on confocal microscopy techniques. Furthermore, morphological characteristics and local hydration of individual particles were identified using an imaging analysis procedure written in Matlab©—R2023b and image analysis through machine learning algorithms written in Python™-3.11. The first model includes segmentation into binary images and labeling particles during water diffusion. The second model includes the expansion of data set selection, neural network training and particle markup. For both models, the effective diffusion follows Fick’s second law for spherical geometry. The effective diffusion coefficient on each particle was computed from the dye intensity during the rehydration process. The results showed that effective diffusion coefficients for water increased linearly with increasing powder particle size and are in agreement with previously used methods. In summary, the models provide two independent machine measurements of effective diffusion coefficient based on the same set of micrographs and may be useful in a wide variety of high-protein powders.publishedVersio
Environmental variables and bottom trawling effort affect the complexity and distribution of soft-bottom octocorals and burrowing megafauna communities in the Gulf of Cádiz
Get PDFBottom trawling significantly impacts benthic communities, reducing habitat complexity and biodiversity. The distribution and abundance of key species in the northeastern Gulf of Cádiz, Spanish waters of Atlantic Ocean, such as soft-bottom octocorals and burrowing megafauna, were examined using video observations and Spatial Distribution Models developed with Random Forest. The study was conducted in the Site of Community Importance “Volcanes de fango del golfo de Cádiz" focusing on depths between 300 and 950 metres depth. The effects of environmental variables and bottom trawling on octocoral distribution and abundance were assessed, and management strategies for habitat protection were proposed. Bottom trawling was found to decrease habitat suitability for large octocoral species while the abundance of Norway lobster was positively correlated with certain values of bottom trawling effort. The study suggests that bottom trawling causes significant reduction in octocoral distributions, substrate homogenization, and habitat differentiation. A 200 km2 area is recommended for a specific bottom trawling regulation to protect soft-bottom octocorals and support the recovery of commercial burrowing megafauna.publishedVersio