Search Results (82)

To evaluate the nutritional enrichment effects of Euphausia superba meal on Moina mongolica Daday, different concentrations of krill meal (26, 39, 52, and 65 mg·L⁻¹) were applied as enrichment supplements, with non-enriched M. mongolica serving as the control. After a 6 h enrichment period, the compositions and contents of amino acids and fatty acids in M. mongolica were analyzed, and the astaxanthin content was simultaneously determined. The results showed that, compared with the control group cultured on a mixed diet of photosynthetic bacteria, yeast, and Nannochloropsis, enrichment with Antarctic krill meal at appropriate concentrations (26–39 mg·L⁻¹) markedly altered the fatty acid profile of M. mongolica. In particular, the levels of highly unsaturated fatty acids (HUFAs), including ∑ω6-PUFA and ∑ω3-PUFA, were significantly enhanced, with a pronounced increase in eicosapentaenoic acid (EPA). Furthermore, the total amino acid content, as well as the contents of six flavor-enhancing amino acids and ten essential amino acids for fish, were significantly higher in the enriched groups than in the control (p < 0.05). However, excessive supplementation of krill meal inhibited the growth of M. mongolica, suggesting a concentration-dependent effect. In addition, enrichment with whole Antarctic krill meal for 6 h did not significantly increase the astaxanthin content in M. mongolica, which may be related to the limited assimilation efficiency within the short enrichment duration. Overall, enrichment of M. mongolica with Euphausia superba meal at appropriate concentrations (26–39 mg·L⁻¹) effectively improves its fatty acid and amino acid composition, thereby enhancing its nutritional value as live feed for aquaculture larvae. Full article

Antarctic krill protein (AKP) was conjugated with three reducing monosaccharides (ribose, glucose, fructose) and five polysaccharides (xanthan gum, konjac glucomannan, inulin, κ-carrageenan, and pectin) via a controlled Maillard-type glycation process (pH 7.0, 90 °C, 24 h). We comparatively evaluated glycation reactivity (color change and degree of glycation), structural responses (particle size, FTIR, intrinsic fluorescence, surface hydrophobicity, and microstructure), and key techno-functional properties (solubility, water- and oil-holding capacities, and emulsifying performance). Monosaccharide-conjugated AKP exhibited stronger browning and higher apparent glycation activity, consistent with the higher reactivity of small-molecule sugars. In contrast, polysaccharide-conjugated AKP showed more pronounced improvements in dispersion-related and interfacial functions, reflecting enhanced steric stabilization and hydration after polysaccharide grafting. Notably, κ-carrageenan conjugation delivered the strongest overall functional enhancement (water-holding capacity ≈ 22.1 g/g; oil-holding capacity ≈ 10 g/g) and the most stable emulsions. These findings clarify how glycosylating-agent size and architecture steer AKP glycation outcomes, providing a practical basis for tailoring AKP ingredients for aqueous and emulsion-based foods. Full article

The objective of this study was to explore the effect of the assembly sequences of wall materials on the structure and properties of Antarctic krill peptide (AKP)-loaded ovalbumin (OVA)–chitosan (CS) nanoparticles (NPs). Two AKP-loaded NPs (CS/OVA-AKP and OVA/CS-AKP) were prepared by changing the sequences of OVA and CS. The results confirmed that CS/OVA-AKP had a smaller particle size (291 nm vs. 320 nm), lower polydispersity index (0.233 vs. 0.282), higher absolute zeta potential (34.4 mV vs. 32.1 mV), and higher encapsulation efficiency (81.6% vs. 75.4%) than OVA/CS-AKP. X-ray diffraction analysis confirmed that AKP was encapsulated in an amorphous state within the NPs. Fourier transform infrared spectroscopy and three-dimensional (3D) fluorescence spectroscopy revealed that electrostatic interactions, hydrogen bonding, and hydrophobic interactions were the primary driving forces for nanoparticle formation, with CS/OVA-AKP demonstrating a stronger OVA fluorescence quenching effect. Compared with OVA/CS-AKP, CS/OVA-AKP exhibited better redispersibility, and CS/OVA-AKP showed greater stability under various environmental factors (thermal treatment, salt concentration, pH, and storage time). During simulated gastrointestinal digestion, CS/OVA-AKP effectively protected AKP from gastric degradation and showed a higher AKP release rate in simulated intestinal fluid (61.1%) than OVA/CS-AKP (53.0%). The release followed the Korsmeyer–Peppas model, with OVA/CS-AKP exhibiting non-Fickian diffusion (n = 0.7500), and CS/OVA-AKP approached Case II transport (n = 0.9889), indicating erosion-controlled release behavior. CS/OVA-AKP also demonstrated higher hypoglycemic activity, with inhibition rates of 41.1%, 37.5%, and 36.1% for α-glucosidase, α-amylase, and DPP-IV, respectively. These findings underscore the important influence of wall-material assembly sequences on the structure and properties of AKP-loaded NPs, offering valuable insights for the development of bioactive peptide delivery systems. Full article

Antarctic krill oil (AKO) is a valuable nutraceutical; however, it is highly susceptible to oxidation. Encapsulation represents an effective strategy to enhance the storage stability of AKO. This study explored a novel approach for encapsulating AKO using sodium alginate (ALG) and gelatin (GLN) to improve its stability, and multiple parameters were systematically evaluated, including oil-loading efficiency, surface oil content, particle size, water activity, and thermal stability. Additionally, core-material retention efficiency, acid value, peroxide value, and anisidine value were measured after accelerated oxidation. The results demonstrated that the optimal encapsulation conditions consisted of an ALG:GLN ratio of 2:1, a 9% CaCl₂ coagulation bath, 750 μm nozzle size, followed by freeze-drying. Under these conditions, the microcapsules achieved an oil-loading efficiency of 62.63% and a surface oil content of 19.21%. The water activity of the microcapsules was 0.516. Thermogravimetric analysis indicated that AKO microcapsules encapsulated with ALG/GLN exhibited higher thermal stability (~300 °C) compared to those encapsulated with ALG alone (~280 °C). When AKO or its microcapsules were subjected to accelerated oxidation at 65 °C, compared to ALG-encapsulation alone, the ALG/GLN encapsulation system significantly reduced the oxidation indicators of the oil, such as acid value (24%), peroxide value (26%), and anisidine value (28%). In conclusion, incorporating GLN into ALG-based microcapsules significantly enhanced the antioxidant capacity of AKO and prolonged its shelf life. Full article

Antarctic krill surimi is a novel type of gel-based food that has attracted increasing attention. However, pure Antarctic krill surimi generally exhibits poor gel-forming properties. Konjac glucomannan (KGM) offers a promising approach to address this limitation due to its gel-forming ability and thermal stability. This study investigated the effect of KGM (0.0–20.0 mg/g) on the functional properties and structural characteristics of Antarctic krill-KGM surimi gels. The results demonstrated that as KGM levels increased, water-holding capacity, whiteness, hardness, chewiness, and gel strength of the composite surimi gels first increased and then decreased, while cooking loss followed the opposite trend. Texture analysis showed that gel strength was significantly enhanced at 10.0 mg/g KGM, reaching a maximum value of 1581.78 ± 12.86 (p < 0.05). Water distribution analysis confirmed that the relative content of immobilized water increased with increasing KGM levels. Fourier transform infrared spectroscopy demonstrated that the Antarctic krill-KGM surimi gels were primarily linked by non-covalent intermolecular interactions. Furthermore, microstructural analysis showed that KGM contributed to a more homogeneous and continuous gel matrix. These results indicate that KGM can modulate electrostatic repulsion, spatial potential resistance, and act as a reinforcing filler in the surimi gel matrix. Overall, the results demonstrated that KGM is a feasible candidate for enhancing the quality of Antarctic krill surimi gels. Full article

Background: Rheumatoid arthritis (RA) is a chronic autoimmune disease characterized by synovitis. The prevalence of RA is estimated to be 0.5–1% worldwide. Methods: This work investigated the therapeutic effects and underlying mechanisms of blue mussel (Mytilus galloprovincialis) oil (BMO) on RA in rats, using green-lipped mussel oil (GMO) and Antarctic krill oil (KO) as controls. Results: The results suggested that BMO, GMO, and KO all alleviated paw swelling in rats and reduced serum levels of rheumatoid factor (RF), anti-cyclic citrullinated peptide (anti-CCP) antibody, and pro-inflammatory cytokines such as TNF-$\alpha$ and IL-17. Histopathological assessment further revealed that BMO, GMO, and KO prevented synovial fibroplasia, mitigated inflammatory cell infiltration, and improved cartilage damage in ankle joints. Overall, BMO exhibited slightly superior alleviating effects compared with GMO and KO. Plasma lipidomics analysis revealed that the lipid metabolites altered by BMO showed significant correlations with RA-related indicators, particularly pro-inflammatory cytokines. Functional enrichment analysis suggested the involvement of inflammation-related pathways, particularly the NF-$\kappa$B signaling pathway. Further validation demonstrated that BMO effectively suppressed the production of inflammatory cytokines (TNF-$\alpha$, IL-17) and the expression of NF-$\kappa$B p65, JAK2, and STAT3 proteins in synovial tissue. And IL-17 production in footpad tissues is closely associated with CD3-positive T cells. Similar effects were also observed for GMO and KO. Conclusions: Collectively, BMO might ameliorate RA by inhibiting NF-$\kappa$B and JAK2/STAT3 signaling pathways. Full article

This study aimed to develop a dietary fiber-rich Antarctic krill composite shrimp surimi gel (AKSG) and to investigate the improvement effects of high protein (HP), high protein and dietary fiber (HPDF), and high dietary fiber (HDF) diet interventions on constipation behaviors and gut microbiota of mice. The results showed that the HPDF group significantly improved defecation in constipated mice, enhanced gastrointestinal peristalsis, and exhibited the most obvious effect on improving the colonic structure. The gut microbial analysis showed that the HPDF group increased the relative abundance of beneficial bacteria and improved the intestinal microbial environment of constipated mice. In addition, all groups effectively regulated the secretion of intestinal neurotransmitters. Inulin significantly increased the fecal water content by binding to water molecules, thus softening feces. Meanwhile, the addition of an appropriate amount of protein could further absorb water in the intestinal tract and relieve constipation. In conclusion, dietary fiber-rich AKSG might be a promising nutritious functional food for constipation relief. Full article

Ice krill (Euphausia crystallorophias) play a key role in the Antarctic coastal ecosystem, yet its spatial growth variability remains poorly understood. This study examined 5298 krill individuals from 52 stations across the Amundsen Sea, transitional waters, and the Ross Sea, collected between 2020 and 2024. Length–weight relationships (LWR) were constructed to derive the condition factor a and the allometric growth exponent b, followed by regional comparisons and environmental response analyses using boxplots, redundancy analysis (RDA), and generalized additive models (GAM). Boxplots revealed that a was significantly higher in the Amundsen Sea and transitional zone than in the Ross Sea, while b was highest and most variable in the Amundsen Sea. RDA indicated that a was primarily associated with depth, latitude, mean temperature, and mean salinity, whereas b was influenced by sea surface temperature, chlorophyll-a, sea ice concentration, and longitude. GAM further showed nonlinear responses of a to mean temperature, mean salinity, and depth, with peaks near −0.5 °C, 34.2 PSU, and 3500 m, respectively. These results suggest that krill in deep, cold, and less-productive transitional zone allocate more energy to body condition (high value a), while those in warmer, moderately productive regions like the Amundsen Sea invest more in structural growth (high value b). This study provides new insights into the environmentally driven growth strategies of ice krill and contributes to understanding its ecological adaptability under changing climatic and oceanographic conditions. Full article

Antarctic krill (Euphausia superba) is a keystone species in the marine ecosystem of the Antarctic Ocean, bringing about significant ecological and economic value. The spatio-temporal distribution of Antarctic krill directly affects commercial fishing; meanwhile, changes in krill population structure play a crucial role in maintaining the balance of the Southern Ocean ecosystem. This study analyzed six years of midwater trawl data, including over 160,000 krill length measurements, to elucidate spatio-temporal dynamics and population composition, providing actionable insights for improved fishery management. Here, we reveal southward migration shifts in krill fishing grounds, with smaller individuals favoring ice-rich southern latitudes. Commercial krill fishing operations preferentially targeted high-density fishing grounds rather than selecting larger individuals. Among the catches, the age 1+ class accounted for the highest proportion at 42.80%, followed by the age 2+ class at 39.42%, with individuals ≥3+ accounting for 17.44%. Although the mean krill length experienced a decline in 2017, it demonstrated a sustained recovery in subsequent years, reaching peak dimensions in 2022. This maximum-growth year also exhibited the highest proportion (12.6%) of individuals within ≥4 age classes. Consequently, the sustained increase in fishing effort in recent years has not resulted in a reduction in the size of individual krill. The mean krill length showed a significant positive correlation with the depth (r = 0.36, p < 0.01) and temperature (r = 0.26, p < 0.01) of the krill cluster, and a significant negative correlation with resource density (r = −0.20, p < 0.01), year (ρ = −0.31, p < 0.01) and latitude (ρ = −0.31, p < 0.01). The length exhibited U-shaped temporal trends, and latitudinal and longitudinal nonlinearity. Body size was positively correlated with depth (p < 0.01), whereas as temperature increased, body size first increased and then remained constant. As density increased, the mean krill length increased first and then slowly decreased. Recent warming intensifies population shifts, with potential cascading effects on ecosystem structure and carbon sequestration. Full article

Antarctic krill, an important marine resource, contains significant arsenic levels, predominantly as the low-toxicity arsenobetaine (AsB). However, the stability of AsB during post-harvest storage and its transformations during human digestion are poorly understood, which is critical for a comprehensive safety assessment. This research investigated the effects of temperature, light exposure, and in vitro simulated digestion on the stability and transformation dynamics of major arsenic species in Antarctic krill. The results revealed that AsB predominated among the arsenic species. AsB remained stable during long-term frozen storage (−18 °C for 5 months) and short-term refrigeration (4 °C for 2 days). However, AsB content decreased significantly during storage at ambient temperature (25 °C) and after prolonged light exposure (>8 h), indicating that improper storage conditions can lead to its degradation. During simulated gastrointestinal digestion, a significant transformation of arsenic species was observed. The content of toxic inorganic As(III) decreased significantly during the gastric phase, while the less-toxic AsB content markedly increased. Furthermore, dimethylarsinic acid (DMA) and As(V) were newly detected during the intestinal phase. These findings demonstrate that arsenic stability in krill is highly dependent on storage conditions. Moreover, the transformations during digestion—notably the decrease in As(III) and increase in AsB—suggest a potential reduction in overall arsenic toxicity upon consumption. This provides a critical theoretical basis for developing storage guidelines and improving human health risk assessments for Antarctic krill products. Full article

Antarctic krill (Euphausia superba) are an essential source of food for whale, seal, several fish, squid and seabird species in the Southern Ocean. Krill also play a major role in biogeochemical cycling and are the target of a growing commercial fishery. Krill can be detected and quantified with echosounders, particularly in swarms, and monitoring krill abundance and distribution is integral to assessing the status of regional populations and managing fisheries. We used echosounders to investigate the hemispherical distribution and behaviour of krill swarms during the Antarctic Circumnavigation Expedition (ACE), a multidisciplinary exercise that included measurements of atmospheric chemistry. Krill swarms were grouped using hierarchical clustering into four principal types: small swarms (on average 2 m high, 25 m long); large swarms (13 m high and 341 m long); deep swarms, which were also densely packed (average depth of 52 m); and shallower swarms, which had lower densities (average depth of 28 m). We found a weak negative relationship between the concentration of atmospheric methane close to the sea surface and the presence of krill. High densities of krill were found in the Amundsen Sea, an area purported to be of increasing importance for krill as the climate changes. Full article

This study estimated the density distribution of Antarctic krill inhabiting an area near the South Shetland Islands using two acoustic analysis methods recommended by the Commission for the Conservation of Antarctic Marine Living Resources, based on data collected using an echosounder installed on commercial fishing vessels. Mean Antarctic krill density for the entire survey area was estimated with two methods recommended by the Commission for the Conservation of Antarctic Marine Living Resources. The mean body length of krill collected using trawl gear was 49.06 ± 4.15 mm (range: 22.0–67.0 mm), with mode of krill observed at 50 mm body length. Using the swarm-based method and the frequency differences according to krill size, the mean densities of krill for stations and transects were 14.86 g/m² (CV = 47.09%) and 13.10 g/m² (CV = 41.16%), respectively. Furthermore, using the dB-difference method for the entire survey area, the average densities were 10.76 g/m² (CV = 43.83%) and 10.14 g/m² (CV = 53.48%), respectively, using the frequency difference based on krill size determined at all stations and per transect. Full article

Antarctica and the Southern Ocean are important sinks in the global mercury (Hg) cycle, and in the marine environment, inorganic Hg can be converted by bacteria to monomethylmercury (MeHg), a highly bioavailable and toxic compound that biomagnifies along food webs. In the Southern Ocean, higher concentrations of Hg and MeHg have typically been reported in the coastal waters of the Ross and Amundsen Seas, where katabatic winds can transport Hg from the Antarctic Plateau and create coastal polynyas, which results in spring depletion events of atmospheric Hg. However, some studies on MeHg biomagnification in Antarctic marine food webs have reported higher Hg concentrations in penguins from sub-Antarctic waters and, unexpectedly, higher levels in juvenile krill than those in adult Antarctic krill. In light of recent estimates of the phytoplankton and zooplankton biomass and distribution in the Southern Ocean, this review suggests that although most studies on MeHg biomagnification refer to the short diatom–krill–vertebrate food chain, alternative and more complex pelagic food webs exist in the Southern Ocean. Thus, juvenile krill and micro- and mesozooplankton grazing on very small autotrophs and heterotrophs, which have high surface-to-volume ratios for MeHg ad-/absorption, may accumulate more Hg than consumers of large diatoms, such as adult krill. In addition, the increased availability of Hg and the different diet contribute to a greater metal accumulation in the feathers of Adélie penguins from the Ross Sea than that of those from the sub-Antarctic. Full article

This study was conducted to investigate the effects of replacing fish meal with either whole-fat or defatted krill powder on the growth, body color, immunity, and related gene expression of red–white koi carp. A total of 630 red–white koi carp with an initial body mass of 13.5 ± 0.05 g were randomly divided into seven groups with three replicates per group and 30 fish per replicate. The control group was fed a basic diet (C0). The other six diets were supplemented with different levels of whole krill meal or defatted krill meal as replacements (10% whole fat, 20% whole fat, 30% whole fat, 10% defatted, 20% defatted, and 30% defatted) in the experimental groups, named W10, W20, W30, D10, D20, and D30, respectively, for a total duration of 60 days. The growth, body color, immunity and gene expression indexes were measured in the koi after completion. The results indicate the following. (1) Compared with C0, the experimental groups of koi showed a significant increase in the specific growth rate (SGR) (p < 0.05), while the hepatosomatic index (HSI) and viscerosomatic ratio (VSI) decreased. Additionally, there was a significant increase in the relative expression level of insulin-like growth factor (IGF-1) in both the liver and muscle (p < 0.05). (2) The experimental groups of koi carp exhibited a significant increase in the carotenoid content in the scales and skin, as well as an elevated relative expression level of the tyrosinase (TYR) gene in the muscle (p < 0.05). (3) The lysozyme (LZM) and superoxide dismutase (SOD) activities were significantly increased in the experimental groups compared to C0 (p < 0.05). Additionally, the SOD activity was significantly higher in the defatted groups than in the whole-fat groups (p < 0.05). Furthermore, the liver alkaline phosphatase (AKP) activity was significantly lower in the D20 and D30 groups compared to the other five groups. (4) The expression level of LPL was significantly lower in the liver and muscle of the whole-fat group compared to the defatted group (p < 0.05). Tissue section observation revealed that the hepatocytes in the W20 and W30 groups exhibited a reduced size and an increased lipid droplet count, while the vacuolar degeneration of the hepatocytes increased in the D30 group. In conclusion, replacing fish meal with whole-fat or defatted krill powder or defatted Antarctic krill meal significantly improves the growth performance, body color, and immunity of red–white koi carp. However, excessive addition of krill meal can easily cause liver damage. The recommended replacement level for whole krill powder is 20% to 30%, while defatted krill powder should be replaced at a level of 10% to 20%. Full article

This study, based on the vessel position data of pump-suction beam trawlers and the integrated species distribution model (ISDM), deeply analyzes the spatio-temporal distribution characteristics of the habitat of Antarctic krill and the contributions of key environmental factors. The Convolutional Neural Network–attention model (CNN–attention model) was used to identify the fishing status of the vessel position data of Norwegian pump-suction beam trawlers for Antarctic krill during the fishing seasons from 2021 to 2023. Variables of marine environment, including sea surface temperature (SST), sea surface height (SSH), chlorophyll concentration (CHL), sea ice concentration (SIC), sea surface salinity (SSS), and spatial factor Geographical Offshore Linear Distance (GLD) were combined and input into the ISDM for simulating and predicting the spatial distribution of the habitat. The model results show that the Area Under the Curve (AUC) and True Skill Statistic (TSS) indices for all months exceed 0.9, with an average AUC of 0.997 and a TSS of 0.973, indicating extremely high accuracy of the model in habitat prediction. Further analysis of environmental factors reveals that Geographical Offshore Linear Distance (GLD) and chlorophyll concentration (CHL) are the main factors affecting habitat suitability, contributing 34.9% and 25.2%, respectively, and their combined contribution exceeds 60%. In addition, factors such as sea surface height (SSH), sea surface temperature (SST), sea ice concentration (SIC), and sea surface salinity (SSS) have impacts on the habitat distribution to varying degrees, and each factor exhibits different suitability response characteristics in different seasons and sub-regions. There is no significant correlation between the habitat area of Antarctic krill and catch (p > 0.05), while there is a significant positive correlation between the fishing duration and the catch (p < 0.001), indicating that a longer fishing duration can effectively increase the Antarctic krill catch. Full article