Oral candidiasis is a significant health concern, especially for elderly individuals. The present study examined chitosan as a potential antimicrobial dental material for Candida albicans treatment. Four types of chitosan products purified from Chionoecetes opilio and Decapodiformes, with varying weight average molecular weight and degree of deacetylation (DAC) were used. Antimicrobial activity was assessed with fungal viability assays, culture turbidity measurements, and live/dead cell staining, while mechanism of action was determined by examining extracellular adenosine triphosphate (ATP) level, reactive oxygen species (ROS) production, and gene expression changes. All examined products exhibited antimicrobial activity, with Decapodiformes-derived chitosan showing better efficacy. Greater molecular weight was correlated with immediate effects and higher DAC with sustained activity. Chitosan treatment increased extracellular ATP and ROS levels, and suppression of genes involved in mitochondrial biosynthesis and drug resistance. These findings suggest potential use of chitosan as an antimicrobial agent in dental materials for oral candidiasis prevention and treatment.

Abstract A total of 743 zoea I and II snow crab (Chionoecetes opilio (O. Fabricius 1788)) were collected in the northwest Atlantic, Canada, in 2012 and 2013. Nine larval appendages were measured for both zoeal stages (410 zoeae I and 333 zoeae II). Snow crab larval morphometric information in the current literature was examined from the Sea of Japan, the northern Pacific, the Northwestern Atlantic, the Barents Sea, and the Kara Sea. Larval size measurements from the present study, conducted at the southernmost sampling location, were compared with those of seven different geographic locations worldwide. Results suggested an increasing trend in the rostro-dorsal spine length with latitude.

Snow crabs (Chionoecetes opilio), a commercially valuable species in Korean waters, have been managed under the Total Allowable Catch (TAC) system since 2002. However, stock assessment has been limited due to difficulties in estimating key ecological traits such as growth, maturity, and mortality. In this study, the Bayesian Schaefer Model (BSM), implemented within CMSY++ framework, was applied to assess the stock status of snow crabs in Korean waters. BSM requires catch and abundance index data, such as catch per unit effort (CPUE) or biomass, as well as prior information on species resilience and relative biomass (B/k). To improve the reliability of B/k priors, we developed a method to calculate them quantitatively using fishery data, sales amounts, and biological information, unlike the qualitative assumptions on stock and fishing conditions proposed in previous research. Two standardized CPUE indices with differing temporal trends in recent years were used as abundance indices. To address the structural uncertainty associated with these divergent trends, we applied a grid-based approach by treating each CPUE index as an independent model scenario and integrating the posterior distributions. A total of 12,000 posterior estimates (6000 per index) were generated through the BSM and used to construct a Kobe plot. Results indicate that the current biomass is slightly above the level supporting maximum sustainable yield, and fishing mortality slightly below the optimal level, suggesting that the stock is healthy and sustainably exploited. Future research should aim to establish a systematic framework for developing quantitative B/k priors to enhance stock assessment accuracy.

Shellfish allergy poses a significant health risk affecting up to 2% of the global population. Comprehensive allergen profiling across species is crucial for improving diagnostics and therapies, given the challenges posed by cross-reactivity. This study aims to identify and compare the allergen profiles of six widely consumed edible crab species. Muscle proteins were extracted from five brachyurans (true crabs) including Charybdis feriata, Portunus pelagicus, Scylla paramamosain, Chionoecetes opilio, and Eriocheir sinensis, as well as the king crab Paralithodes camtschaticus, and were analyzed for IgE reactivity with serum samples from 29 crab-allergic individuals and three nonallergic controls. IgE-binding proteins were identified by immunoblotting followed by mass spectrometry. Recombinant king crab allergen was purified and tested on ELISA against samples from 50 crab-allergic individuals, with its specific IgE reactivity evaluated by inhibition ELISA and immunoblot. Comparison of the gene expression of the identified allergens along with reported epitopes was revealed through comparative transcriptomics and multiple sequence alignments. IgE reactivity was detected only in serum samples from crab-allergic individuals. Immunoblotting distinguished eight putative crab allergens and three registered crab allergens. The protein and allergen profiles of the king crab were distinct from the brachyuran crab species based on dendrogram analysis; malate dehydrogenase (MDH) was distinctly reactive only in king crab with 41.4% sensitization on immunoblot, while recombinant MDH displayed a 14% sensitization rate, leading to its registration as Para c 11. MDH homologs from true crabs showed minimal inhibition to Para c 11 (< 10%). Based on transcriptomic analysis, the identified crab allergens showed similar expression across species, while the sequence and epitope similarity exceeded 68%. The study provides molecular insights into crab allergen diversity and highlights the potential for species-specific crab allergies with Para c 11 as a potential king crab-specific allergen, paving the way for personalized and advanced component-resolved diagnostics.

Snow crab (Chionoecetes opilio) is considered an invasive species in the Barents Sea, with the first observations dating back to 1996. The Norwegian commercial snow crab fishery started in 2012. In this fishery conical baited pots are adopted, similar to fisheries in other areas that target snow crabs. Over the last decade, different management measures have been implemented to ensure sustainability in this relatively new fishery. One central challenge is pot loss during deployment caused by challenging weather and operational conditions. Lost snow crab pots exhibit considerable potential for the continuous capture of crabs, so-called ghost fishing, which has been documented during lost gear retrieval and experimental trials. This study accounted for different snow crab pot loss scenarios and associated economic implications. The results show that given the substantial number of pots on snow crab fishing vessels, even small variations in pot loss rates (pot losses ranging from 0.5 to 3.0%) could result in considerable differences in ghost fishing amounts and the associated environmental and economic effects. The estimated amounts of ghost fishing in this study ranged from 11.5 to nearly 70 tonnes of ghost-fished crabs over a 3-year period, assuming 0.5–3.0% pot loss scenarios, resulting in significant differences in the amount of ghost-fished snow crabs and the value of the ghost fishing catch. These results highlight the importance of incentives and technical measures that can reduce pot losses and the associated ghost fishing time.

Changes in the Communities in the Southwestern Kara Sea as a Result of the Snow Crab (Chionoecetes opilio) Invasion

ABSTRACT Introduction The nutritional composition of snow crabs (Chionoecetes opilio) varies substantially by geographic origin. This study aimed to determine differences in the fatty acid profiles of Russian and Korean snow crabs and to identify origin-based biomarkers. Methods Fatty acid analysis and multivariate statistical analysis were performed to identify distinguishing compounds. Results Significant differences (p < 0.05) were found in docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), with cut-off values set at 18.90% and 33.55% of total fatty acids, respectively. Discussion A statistical model was developed and validated to distinguish geographic origin, providing a reliable tool for food origin verification and supporting regulatory efforts and consumer confidence.

In the Barents Sea commercial snow crab (Chionoecetes opilio) fishery, an increase in catch efficiency of the conical pots is important for the profitability of the industry. Light emitting diodes (LEDs) have previously been tested for increasing catch efficiency of the snow crab pots. These earlier experiments have shown varying results ranging from large increase in snow crab catches to no significant effect. These experiments have used different pot soaking times; however, the soaking time might affect the impact of LEDs on catch efficiency. In commercial snow crab fishery, the pot soak time is varying which has not been considered in earlier experiments testing the effect of LEDs. Therefore, this study examined whether pot soaking time can explain the observed differences in relative catch efficiency of snow crab pots with and without LEDs with soak times ranging from 2 to 14 days in the Barents Sea snow crab fishery. For target sizes of snow crab (≥95 mm carapace width), results indicated an increase in catch efficiency between 10 and 30% for pots with LEDs with exception of one experiment using six days soak time. However, experimental results were subjected to large uncertainties and, except from one experiment with five days soak time, the estimated increases were nonsignificant. Furthermore, the pot soak time was not found to impact the effect of white LEDs on capture efficiency.

Impact of environmental conditions on spatial distribution of size-sex groups is described statistically for snow crab Chionoecetes opilio. Based on the relationships identified, absolute values of catches are calculated for each such group. Machine learning approach is implemented for the feature engineering and statistical relationships evaluation. The approach can be adopted for other benthic stocks.

Ghost fishing by self-baited lost, abandoned or discarded pots in snow crab (Chionoecetes opilio) fishery

The introduction of a large predatory snow crab, Chionoecetes opilio, into the Kara Sea is a unique situation where the impact of an invasive species affecting an otherwise undisturbed ecosystem can be observed unhindered by other ecosystem stressors. Trophic interactions are one of the principal relationships between animals and can help assess an ecosystem's stability. The trophic positions and sources of organic material for the most common benthic species of Blagopoluchiya Bay sampled at different stages of the invasion were calculated using stable isotope analysis. The most pronounced changes in the trophic web occurred amongst the megabenthic species, where previously most abundant deposit-feeding ophiuroids have disappeared. However, the benthic species' trophic position and primary production source preference did not change. A sea star, Urasterias lincki, remained the highest carnivore in the bay, and the invasive crab remained at a lower trophic level, showing higher omnivory in its diet. Any changes in the consumers' prey items were within the same trophic level. Overall, active predators became one of the most abundant feeding mode groups. The average weighted trophic position of all megabenthic species increased to the third trophic level, where mostly secondary consumers remained.

Profitable marine invasions can occur when a newly arrived invasive species not only negatively changes ecosystem characteristics but is also exploited as a valuable market commodity. Such species pit existing ecosystem production values against potential value paths as their presence instigates management decisions that may vary from favoring a conservative, status quo approach on one end to a more risk-loving, adaptive approach on the other. Despite commitments to environmental treaties for limiting spread, local interests may purposefully support growth of invasions for their benefit. Potential value paths will depend not only on the ecological changes in the natural capital supporting the profitable resource extraction but also the user rights developed to address the changing asset structure and productivity. Current economic thinking suggests that the stronger the user rights in addressing questions of exclusivity, security and duration, the higher the gains to the present value of expected benefits from the rights. We discuss how both scale and uncertainties regarding irreversible ecological value and productivity shifts may require refinement of this theory. We explore the Barents Sea Snow Crab (Chionoecetes opilio) fishery, with particular attention to the Norwegian approach to its management. The uncertain ecological impacts of this invasive species have led to international disputes and significant management challenges. Norway has implemented exclusionary policies by designating the crab as sedentary to limit foreign access, sparking conflicts over the Svalbard Treaty. These unilateral actions have led to fines, court cases, and diplomatic tensions. As the Snow Crab expands toward sensitive Arctic habitats, a broader governance approach is needed. We take a critical look at the exclusivity, security, and durability of property rights associated with the Norwegian Snow Crab fishery, assessing their inherent weaknesses and implications since the onset of the fishery in 2012. As there is a growing interest in developing profitable resource exploitation and fisheries for new, often invading species, the Norwegian Snow Crab fishery provides valuable lessons and guidance for governance and management of such resources, aiming to mitigate risks and foster economically viable and environmentally responsible practices.

As a part of a marine expedition on the R/V «Dalnye Zelentsy» along the western coast of the Novaya Zemlya archipelago, an assessment of megabenthic species diversity and biomass in bycatch of trawl was carried out in August 2023 specimens of 29 taxa belonging to 6 phyla were identified during the survey. The highest species diversity (20 species) was recorded in the northern coastal area of the Novaya Zemlya archipelago, where the dominant forms in terms of biomass were sea urchins Strongylocentrotus pallidus – 237.1 kg/km2. A tendency for a 5-fold decrease in megabenthos species diversity and a decrease in the average biomass of organisms – from 17.2 to 0.47 kg/km2 was detected with transition from north to south. The association of sea urchins S. pallidus and brittle stars Gorgonocephalus sp. (84 % biomass share of representatives in bycatch) is identified in the north of the study area, which is replaced by the association of sea urchins S. pallidus and crustaceans Chionoecetes opilio (74.6 %) when moving to the south. According to the results of the RDA analysis, the effects of trawl fishing and type of water mass have the greatest impact on species diversity and biomass of megabenthic organisms. Trawling intensity, type of water mass, and sediment characteristics explain 75 % of the observed variability in these biological parameters.

ABSTRACTSnow crab (Chionoecetes opilio) in the eastern Bering Sea (EBS) supports a valuable crab fishery that harvests large males. To better understand the potential impact of the presence of snow‐Tanner hybrids (C. opilio × C. bairdi) on snow crab mating dynamics, the maternal lineage of hybrids was evaluated using single nucleotide polymorphisms (SNPs). Contrary to results from a previous study that indicated hybrids result only from crosses between Tanner crab (C. bairdi) males and snow crab females, results from this study showed hybrids result from bidirectional parental crosses. SNP and microsatellite markers were used to evaluate the species and number of males detected as mates in female sperm reserves acquired during mating and as sires among embryos in brooded clutches. The incidence of interspecies mating between female snow crab and Tanner crab or hybrid males was low (2%), suggesting interspecies mating is not currently a pressing fishery management concern. Most females had stored sperm from either a single mate (59%) or two mates (32%), which reflects fewer mates than observed for other snow crab populations. Few females were observed with either no stored sperm (5%) or sperm from three to four mates (4%). Single (82%) or dual (18%) paternity was found among embryos in brooded clutches. Sperm from some mates appeared to be fully utilized for fertilization of the brooded clutch for 35% of females. In contrast to findings for other snow crab populations, no significant differences were detected in the numbers of mates or sires between primiparous and multiparous females. The low extent of polyandry observed may suggest that female snow crab in the EBS have limited mating opportunities, potentially leading to insufficient sperm reserves to fertilize subsequent clutches without remating.

The introduction of a new species can lead to substantial changes in a new ecosystem. Local and introduced species' survival depends on their ability to adapt to the new environment. Studying such adaptations is often hindered by multiple factors affecting the ecosystem. The introduction of a large predatory snow crab, Chionoecetes opilio, into the Kara Sea, is a unique invasive species affecting an otherwise undisturbed ecosystem. The crab has caused drastic changes in the macro- and megabenthic taxonomic structure, abundance, and biomass of the most common species in an Arctic fjord, Blagopoluchiya Bay. Stomach content and stable isotope analysis were applied to study crabs' feeding habits. As the abundance of the most common prey items diminished, the crabs switched to other less accessible food. Prior to substantial changes in benthic communities, the diet of the snow crabs was similar to that of other invaded and native areas, where animal food predominates. However, with the degradation of the ecosystem, detritus contribution has substantially increased. The changes in prey items did not change the crab's trophic status, and they continued to feed within the same trophic niche. In the depleted benthic communities of Blagopoluchiya Bay, the snow crab is forced to use all available food sources.

Most likely, the non-indigenous snow crab opilio, Chionoecetes opilio, entered the Kara Sea from the Barents Sea, both due to the migration of adults and with currents at the larval stage. At the moment, all bottom stages, including mature individuals and a large number of pelagic larvae are present in the Kara Sea. However, the origin of the larvae has not yet been clarified. The larvae that hatched in the Kara Sea should be at an earlier stage of development compared to the Barents Sea larvae that got here due, to later development of phytoplankton and, accordingly, later hatching. The larvae of the snow crab Chionoecetes opilio and the spider crab H. araneus were collected in the central and southwestern parts of the Kara Sea in July — early August 2019 by the Bongo zooplankton net 60 cm in diameter. It was established that the larvae were unevenly distributed across the Kara Sea. The main concentrations were found on the border with the Barents Sea in the St. Anna Trough (up to 860 ind./m2), and relatively high concentrations of larvae were noted in the southwestern part, where their abundance at the stations varied from 18 to 302 ind./m2. In the zone of the Ob-Yenisei plume, crab larvae were absent or their abundance was minimal. Using molecular genetic methods, the species identity of 361 larvae (344 C. opilio and 17 H. araneus) was reliably determined, and measurements of a number of morphological structures were made for 401 larvae. Significant differences in size at the zoea stage II between C. opilio and H. araneus were established. In most of the Kara Sea in July 2019, in zooplankton samples, crab larvae were represented by zoea I C. opilio with rare specimens of zoea I H. araneus of the Kara Sea origin. Only in the southwestern part, on the border with the Barents Sea, the presence of zoea II C. opilio and H. araneus was observed in samples with an increase in the proportion of the latter species in catches, which probably originate from the Barents Sea.

Nunatsiavut is a self-governing Inuit territory in northern coastal Labrador, where cultural knowledge and social values are incorporated into co-managed subsistence and commercial fisheries. Snow crab (Chionoecetes opilio), known as Putjotik in Inuttitut (the Nunatsiavut dialect of Inuktitut), is a co-managed fishery through the Torngat Joint Fisheries Board (TJFB) and plays a crucial role in sustaining the community of Makkovik. Arctic Char (IKaluk) is also harvested in co-managed subsistence and commercial fisheries, and is a staple in local economies and culture. In 2022, the TJFB partnered with Inuit educators to foster youth stewardship in a project called Paigitsiaguk. The Paigitsiaguk project bridges Inuit and scientific knowledge to nurture cultural values and environmental stewardship through providing place and land-based resources to educators. The project team created a comprehensive database of curriculum outcomes required by the Newfoundland and Labrador school system, and then designed culturally relevant learning activities that presented Inuit knowledge with science and social studies for students in Nunatsiavut. These resources include learning activities that are organized into education kits: one of which is centered on Putjotik and another on IKaluk. The Putjotik kit has 23 activities tailored to meet grade-specific learning outcomes, while the IKaluk kit provides 12 place-based learning activities appropriate for multiple grade levels. By providing localized and culturally relevant education resources to teachers that revolve around stewarding local fish species and their ecosystems, youth are connecting to their communities and to the coastal environment. Educational resources and learning activities reflect Inuit and scientific knowledge systems, and position teachers as facilitators to encourage students to learn from the land and Elders, knowledge holders, fishers, scientists, and managers. This paper reflects the promising futures that this work can contribute to; from facilitating intergenerational knowledge transmission from knowledge holders to youth, to encouraging self-determined stewardship activities that encourage care for the ocean and its fisheries.

Identifying the species of king crab in processed products is crucial to prevent food fraud and harm to consumers. A rapid real-time PCR method was developed to identify three crab species (Chionoecetes japonicus, Chionoecetes opilio, and Paralithodes camtschaticus) in crab products within 30min. The method involved direct DNA extraction and utilized species-specific primer sets targeting mitochondrial cytochrome C oxidase subunit I (COI) and internal transcribed spacer (ITS1) for the three crab species. Specificity and sensitivity tests demonstrated consistent melting temperatures and cycle threshold values and a detection limit of 0.001ng DNA. The ultrafast PCR successfully distinguished the three crab species in 24 commercial products, indicating its rapid, specific, and sensitive potential for on-site identification of crab species in commercial food products.

The first quantitative video survey of the benthic megafauna was carried out on a transect in the eastern part of the Kara Sea from the slope of the Voronin Trough to the upper shelf in the depth range from 1680 to 70 metres. The data were obtained using the TU-V “Videomodule” during the 89th cruise of the R/V “Akademik Mstislav Keldysh” in autumn 2022. It was shown that the megabenthos in this area differs significantly from that of the western part of the sea and Blagopoluchiya Bay (Novaya Zemlya). In the eastern part of the Kara Sea, echinoderms dominated, among which ophiuroids were in the first place, whereas in the western part of the sea and in the Blagopoluchiya Bay, the key component of the megafauna was the snow crab Chionoecetes opilio. Single adults of Ch. opilio were recorded for the first time at almost all stations in the eastern part of the sea, but, in contrast to the western area, the snow crab has not yet become dominant here and has not influenced the benthic communities.

The snow/pink crab (Chionoecetes opilio) and Northern shrimp (Pandalus borealis) are widely distributed in the North Atlantic Ocean. During processing/consumption, about 80% of the harvest is discarded as processing waste, which is a rich source of protein, chitin, minerals, and carotenoids. This study, for the first time, investigated the proximate composition and individual amino acids, minerals, and carotenoids from different body parts (carapace, shoulder, claw, tip, and leg) of snow crabs and shrimp shells. Shrimp proteins were found to be abundant and well-balanced in their amino acid composition. Compared to shrimp shells, a lower content of amino acids was found in the snow crab, depending on the part of the shell used. Moreover, crab shells, mainly crab claws, contained a higher (p < 0.05) level of chitin compared to shrimp shells. Seven micro-elements (Mn, Fe, Cu, Zn, As, Ba, and Ce) and six macro-elements (Ca, Na, K, Mg, P, and Sr) were identified using inductively coupled plasma-mass spectrometry (ICP-MS). Among them, calcium and iron were higher in crab carapaces (p < 0.05), followed by shrimp shells and other crab shell segments. Additionally, shrimp and crab carapaces contained a significant level of carotenoids, and these were mainly composed of astaxanthin and its mono- and diesters, along with zeaxanthin, astacene, canthaxanthin, and lutein. Thus, this investigation provides detailed information to allow upcycling of shellfish waste and addresses the knowledge gap concerning the availability of various nutrients in different crab sections and shrimp shells.