Search

Copyright of Journal of Food Safety & Quality is the property of Journal of Food Safety & Quality Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Experimental Technology & Management is the property of Experimental Technology & Management Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this paper, we propose non-negative intensity (NNI) as an alternative intensity-based technique for target strength identification in marine ecosystem research. NNI identifies local surface regions of a body with positive-only sound power contributions. NNI is employed for sound scattering by fluid-loaded, fluid-filled elastic structures with weak scattering boundary conditions. Three numerical case studies are presented for which fully coupled fluid-structure interaction models based on the finite element method (FEM) and the boundary element method (BEM) are developed. To validate the three-way coupling between the structural and fluid domains, an elastic shell submerged in water and filled with different internal fluids is initially considered. Results for the scattered acoustic intensity obtained numerically are compared with analytical results from the literature. Models representing Antarctic krill of simple and complex geometry are developed. A 3×3 cylinder array representing a simplified aggregation of krill is also presented. Target strength is calculated using both the scattered intensity and NNI for different incident excitation angles. Results for NNI identify the surface regions of an individual organism or group of organisms with the greatest contribution to the scattered sound at the target strength locations. [ABSTRACT FROM AUTHOR]

Antarctic krill mainly inhabit the Antarctic Ocean, not far from Antarctica, especially the Weddell Sea, where krill is dense. Marine fisheries have reached new levels, but the topic of sustainable use of marine fishery resources is far from reaching the required levels. In order to study the sustainable development of the Antarctic krill environment, this paper studies the living environment and applicability of Antarctic krill based on system dynamics, and provides some references for the sustainable development of marine resources. Mentioned the use of case analysis method, literature analysis method and other methods to collect data, build a Model, and read and analyse a large number of related literatures through the literature survey method. The experimental results proved that the salinity has a significant effect on the survival rate of Antarctic krill (p < 0.05). When the salinity is 34, the molting frequency reaches its maximum value, which is 70 %. It is concluded that the ability of Antarctic krill to adapt to gradual changes in salinity is stronger than that of sudden changes in salinity, and the suitable salinity for survival is 30-42. With 34 as the basic salinity, when the salinity rises within a certain range, the molting rate of krill will increase, and as the salinity decreases, the molting rate will gradually decrease. This shows that improving the environmental resources of Antarctic krill is an effective method for improving salinity. [ABSTRACT FROM AUTHOR]

In this paper, Antarctic krill was used as the raw material. Physicochemical indexes, flora changes and flavor substances of shrimp paste with different salt concentrations and fermentation days were investigated. The main dominant bacterial groups in the shrimp paste samples were detected by 16S rDNA high-throughput sequencing technology. At phylum level, the dominant bacteria groups were Proteobacteria , Firmicutes and Actinobacteria , while at genus level, the dominant bacteria groups were Staphylococcus , Psychrobacter and Herbaspirillum. Qualitative analysis of volatile compounds in shrimp paste samples by GC-IMS technique. A total of 29 volatiles were detected, and a total of 37 volatile flavor compounds including dimers and trimers were isolated and identified, including 16 aldehydes, 8 alcohols, 8 ketones, 2 ethers and 3 esters. Establishing correlations between important colonies and volatile compounds. • The flavor changes of shrimp paste under different salt concentrations and fermentation days. • Changes in the main microbial communities in shrimp paste under different salt concentrations and fermentation days. • 29 volatile substances were detected in shrimp paste samples. • There is a significant correlation between volatile compounds and bacterial colonies. [ABSTRACT FROM AUTHOR]

Antarctic krill (Euphausia superba, hereafter krill) is a pelagic living crustacean and a key species in the Southern Ocean ecosystem. Krill builds up a huge biomass and its synchronized behavioral patterns, such as diel vertical migration (DVM), substantially impact ecosystem structure and carbon sequestration. However, the mechanistic basis of krill DVM is unknown and previous studies of krill behavior in the laboratory were challenged by complex behavior and large variability. Using a new experimental set-up, we recorded the swimming activity of individual wild-caught krill under light–dark cycles. Krill individuals exhibited differential phototactic responses to the light regime provided. However, using a new activity metric, we showed for the first time a consistent nocturnal increase in krill swimming activity in a controlled environment. Krill swimming activity in the new set-up was strongly synchronized with the light–dark cycle, similar to the diel vertical migration pattern of krill in the field when the krill were sampled for the experiment, demonstrated by hydroacoustic recordings. The new set-up presents a promising tool for investigating the mechanisms underlying krill behavioral patterns, which will increase our understanding of ecological interactions, the spatial distribution of populations, and their effects on biogeochemical cycles in the future. [ABSTRACT FROM AUTHOR]

The northwestern Antarctic Peninsula is an important spawning, recruitment, and overwintering ground for Antarctic krill. The region is warming rapidly, and the current impacts of climate and environmental variability on the reproductive cycle of krill remain unclear. Here, we examine the reproductive stage of female krill in the austral winter from 2012 to 2016 in relation to climate and environmental data to assess what factors influence the timing of reproductive development. We observed significant interannual variability in the degree of maturation in female krill, ranging from 48% of female krill measured at a station in 2016 to a maximum of 94% of female krill measured at a station in 2014. On average, across all five years, three-quarters of the female krill sampled were in the stage known as previtellogenesis, the point at which the onset of sexual maturity begins. The preceding spring, summer, and autumn Southern Annular Mode and the Multivariate El Niño Index explained most of the variance in the data and indicated a strong, preconditioning storm-related effect on environmental conditions leading up to winter, affecting krill maturation status at the end of the winter season. Results from our study can be used to improve krill population models that are necessary for the management of the krill fishery and for conservation at the northwestern Antarctic Peninsula. [ABSTRACT FROM AUTHOR]

The present study is the attempt to combine oceanologic measurements and biochemical analysis, which is as possible to implement on board as in a laboratory with chosen certain statistics to reveal trophic conditions and the environment state in which Antarctic krill live in season in real time on site. The fatty acid constituents of total lipids in juvenile and mature Antarctic krill sampled from the Bransfield Strait (BS), the Antarctic Sound (AS), and waters at the eastern tip of the Antarctic Peninsula (AP) collected during the 87th cruise of the R/V Akademik Mstislav Keldysh in January–February 2022 were analyzed. The fatty acid (FA) profile in juvenile and mature Antarctic krill was studied by gas chromatography with a mass selective detector to identify the qualitative composition and a flame ionization detector to quantify the studied FAs. Using NMDS analysis (quantitative panel), great difference was found between krill from the BS compared to krill collected in the AS and the AP. The differences are reliable owing to the following 16 FAs, most of them trophic biomarkers of microphytoplankton, and suggest regional differences, mainly in abundance and ability of forage objects. CTD measurements discuss the abiotic factors (potential temperature, salinity, and chlorophyll "a"). Compensatory modifications of the composition of FA components in Antarctic krill inhabiting different water areas are a way of maintaining the species' viability under certain and variable habitat conditions. [ABSTRACT FROM AUTHOR]

The extent to which marine species avoid survey vessels is the subject of considerable debate, with stimuli such as noise and pressure waves receiving particular attention. By some estimates, avoidance behaviour is a major bias in the assessment of pelagic species distribution and density. Surveyors of the marine environment are increasingly using autonomous platforms; thus the question of avoidance of these novel platforms must be considered. A long-duration, underwater glider with an integrated echo-sounder was deployed to measure the density and distribution of Antarctic krill. We show that krill reacted to the glider, despite the low-noise profile of the platform. The weighted-mean depth of krill swarms was observed to deepen when a glider came within 30 m. In addition, we observed a near-range decrease in depth-integrated acoustic backscatter and we demonstrate that this effect is not explained by the instrument's acoustic footprint. The potential triggers for these behaviours are discussed. The list of sensors available for use on a glider is increasing, with some producing sound, light or other potential stimuli for behavioural response. Our paper demonstrates that caution should be used when designing mission payloads and in the interpretation of acoustic data for animal density from gliders. A key consideration for surveyors may be the factoring in of an exclusion zone from their analyses. • Antarctic krill swarms responded to the presence of the glider, interpreted as an avoidance response. • Near-range echo was less than expected without avoidance; simulation shows sampling does not account for the difference. • Slope of swarm centre of mass suggests and effect up to 40 m below the glider. • Often thought of as quiet vehicles, glider surveys of biomass will need to account for target disturbances. [ABSTRACT FROM AUTHOR]

To reduce costs associated with the detection and population assessment of Antarctic krill and diversify the single detection approach, our team designed and deployed a drifting sonar buoy for krill detection in the waters surrounding Antarctica. The experimental results indicate that the drifting sonar buoy fulfills its primary functions and meets the requirements for krill detection in designated marine areas. The initial experiment lasted seven days, during which the buoy collected 157 records of speed and location data as well as 82 records of sea surface temperature and acoustic data, demonstrating its potential for krill detection. The experiment also revealed shortcomings in the initial design of the drifting sonar buoy, leading to proposed improvements. The paper further compares the advantages and disadvantages of the drifting sonar buoy and traditional fishing vessels in krill detection with the buoy offering unique benefits in low-cost deployment, labor savings, broad monitoring range, and continuous real-time data monitoring. The drifting sonar buoy serves as an excellent complement to fishing vessels in krill detection.

At present, the primary fishing method of Antarctic krill is beam trawl, in which the fishing vessel drags the beam equipped with nets through the trawl warp for midwater trawling. Due to the behavioral characteristic of collective activities, the shoal of Antarctic krill often appears in some specific depths of the sea. The existing fishing method needs to adjust the trawling depth by modifying the length of the trawl warp and the navigation speed of the vessel, which cannot adjust the trawling depth independently. To solve this problem, we proposed a depth variable device installed on the beam to adjust the trawling depth independently, aiming to track the depth where the shoal of Antarctic krill is located for accurate fishing. Investigate the hydrodynamic feature of the proposed beam trawl device by numerical analysis and water channel experiment to design the wing's profile and determine the effective range of angle of attack. It was found that when the angle of attack of the wing is 0°–17.7°, the regulation effect of depth adjusting is better. The analysis results can be used as the parameter basis for compiling the control program for the depth variable beam. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Functional Materials / Gongneng Cailiao is the property of Chongqing Functional Materials Periodical Press and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

There is an emerging consumption of the Antarctic krill (AK) muscle‐based food due to its excellent nutritional value and enormous biomass storage capacity. However, the coarse texture of the muscle and the weak gelling properties of AK protein impede its expansion in surimi‐based products. This investigation successfully prepared heat‐induced gels of AK surimi with desirable textural properties by including Litopenaeus vannamei in varying proportions. Higher concentrations of L. vannamei resulted in improved three‐dimensional printability, greater water‐holding capacity (WHC), larger viscoelastic modulus, and a well‐formed microstructural matrix of AK surimi, due to an increased level of myofibrillar protein. Compared with AK, L. vannamei muscle had double the salt‐soluble protein content, which was corroborated by increased intensity of bands of actin, paramyosin, tropomyosin, and myosin light chains on reducing SDS‐PAGE. DSC results indicated that a high ratio of L. vannamei elevated the denaturation temperature and enthalpy of myosin, sarcoplasmic protein, and actin, suggesting a high degree of cross‐linking. It was also found that when hydroxypropyl cassava starch was added at 0.5% (w/w), WHC and gel strength were further improved with a more compact gel matrix. The successful preparation of unwashed mixed surimi with AK meat fully exploited in this study provides an option for AK surimi‐based product industrialization. [ABSTRACT FROM AUTHOR]

Antarctic krill is widely distributed in Antarctic waters, with rich resource reserves. It is the largest single catching biological resource in the world′s oceans. This paper combed the operation of global Antarctic krill fishing and processing ships, analyzed the development and utilization of Antarctic krill and the development status of fishing and processing ships in major countries, selected "Furong Sea" and "Antarctic Endurance", made a comparative analysis between China′s Antarctic krill fishing and processing ships and Norwegian fishing boats, and pointed out that there were still some problems in the development of Chinese Antarctic krill fishing and processing ships. There were problems in the production mode, the traditional fishing methods of fishing vessels needed to be improved and the on-board processing technology needed to be further improved. Based on this, it was considered that China should promote transformation and upgrading and form a new Antarctic krill fishing and processing fishing vessel system in the future; strengthen the industrial quality and constantly improve the fishing gear and equipment level of fishing vessels; improve the processing links and break through the bottleneck of on-board processing technology, to provide help to the development of China′s Antarctic krill fishing industry.

The objective of this study was to determine the quality changes and shelf life of ready-to-eat roasted Antarctic krill, either untreated (CT) or treated with sodium diacetate (SD) or sodium diacetate and a deoxidizer (SDD), during storage at room temperature (25°C) by using sensory, physiochemical, and microbial assessment. Additionally, fluoride accumulation in this food product was used to evaluate its safety. Analysis showed that the addition of SD and SDD resulted in better sensory scores compared of that of CT samples (P <0.05). Accordingly, microorganism growth and total basic nitrogen (TVB-N) were maintained at a low level for the duration of storage with SD and SDD treatments. The total viable counts of SD and SDD reached (4.58 ± 0.08) log (CFU g−1) and (4.20 ± 0.11) log (CFU g−1), respectively. The mold was found after 6 and 18 days for SD and SDD treatment, and the numbers reached 5.2 × 106 and 8.5 × 104 respectively at the end of shelf life. The TVB-N values from CT continuously increased during the whole storage. While TVB-N values from SD and SDD remained significantly less change (P <0.05) during the early 20 days of the storage, and the values reached (12.11 ± 0.07) mg (100 g)−1 and (10.88 ± 0.15) mg (100 g)−1 on day 33 and day 70, respectively. Importantly, SDD treatment effectively minimized the oxidation values and retained the color of ready-to-eat roasted Antarctic krill. Our results showed that the shelf life of ready-to-eat roasted Antarctic krill treated with SDD was extended by up to 52 days. Additionally, rats fed ready-to-eat roasted Antarctic krill showed accumulation of fluoride exclusively in the thighbone. The accumulation of fluoride residues in the thighbone showed concentration-dependent. The concentrations of fluoride residues in rats were (1760.03 ± 38.21), (2371.52 ± 42.15) mg kg−1 and (3615.44 ± 30.53) mg kg−1, which were less than sodium fluoride feeding group (4621.01 ± 28.67) mg kg−1. The results suggested that the SD and SDD treatments led to better quality and shelf life extension of ready-to-eat roasted Antarctic krill during storage at room temperature (25°C). Therefore, the ready-to-eat roasted Antarctic krill can be of great interest to the seafood industry. [ABSTRACT FROM AUTHOR]

Antarctic krill (Euphausia superba) of the Euphausiidae family comprise one of the largest biomasses in the world and play a key role in the Antarctic marine ecosystem. However, the study of E. superba-derived microbes and their secondary metabolites has been limited. Chemical investigation of the secondary metabolites of the actinomycetes Nocardiopsis sp. LX-1 (in the family of Nocardiopsaceae), isolated from E. superba, combined with molecular networking, led to the identification of 16 compounds a–p (purple nodes in the molecular network) and the isolation of one new pyrroline, nocarpyrroline A (1), along with 11 known compounds 2–12. The structure of the new compound 1 was elucidated by extensive spectroscopic investigation. Compound 2 exhibited broad-spectrum antibacterial activities against A. hydrophila, D. chrysanthemi, C. terrigena, X. citri pv. malvacearum and antifungal activity against C. albicans in a conventional broth dilution assay. The positive control was ciprofloxacin with the MIC values of <0.024 µM, 0.39 µM, 0.39 µM, 0.39 µM, and 0.20 µM, respectively. Compound 1 and compounds 7, 10, and 11 displayed antifungal activities against F. fujikuroi and D. citri, respectively, in modified agar diffusion test. Prochloraz was used as positive control and showed the inhibition zone radius of 17 mm and 15 mm against F. fujikuroi and D. citri, respectively. All the annotated compounds a–p by molecular networking were first discovered from the genus Nocardiopsis. Nocarpyrroline A (1) features an unprecedented 4,5-dihydro-pyrrole-2-carbonitrile substructure, and it is the first pyrroline isolated from the genus Nocardiopsis. This study further demonstrated the guiding significance of molecular networking in the research of microbial secondary metabolites. [ABSTRACT FROM AUTHOR]

We used 22 years of seasonally and spatially consistent monitoring data to explore marine predator–prey numerical response relationships. Specifically, we tested whether indices of offspring performance (e.g. offspring mass near the time of their independence and/or growth rate) from three Antarctic krill-dependent predators, showed positive relationships with estimates of krill density, determined using fishery-independent acoustic surveys undertaken towards the middle of the predator breeding season. Results showed that indices of predator reproductive performance had little relationship with krill density. In most years, average krill densities were higher on-shelf than off-shelf, potentially providing ecological buffering for predators provisioning offspring. Interestingly, positive response relationships were evident between predator offspring mass and the spatial distribution of krill, measured using indices that represent levels of inequality (patchiness) in krill distribution. These relationships were strongest using indices that reflected the off-shelf krill spatial distribution. We found that krill density and predator offspring mass were also both negatively influenced by sea surface temperature and the Southern Annular Mode, indicating that the environment exerts strong control over ecosystem processes. Finally, we consider the relevance of our results to the ecological framework used by managers responsible for setting catch limits for the regional fishery for krill. [ABSTRACT FROM AUTHOR]

The objective of the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR) is conservation (CCAMLR, 1980), and the management provision that distributes krill catches throughout the Scotia Sea expires in November. Conservation does not require undetectable ecosystem effects of fishing, but CCAMLR intended to manage the krill fishery so that any such effect would be minor. Conservation Measure 51-01 specifies two annual catch limits: an aspirational limit (5.61 Mt, the "precautionary catch limit") and an interim "trigger limit" (620 kt) (CCAMLR, 1991). Keywords: Antarctica; Antarctic krill; CCAMLR; fishery management; krill predators; precaution; risk assessment EN Antarctica Antarctic krill CCAMLR fishery management krill predators precaution risk assessment 1 4 4 10/04/22 20221001 NES 221001 INTRODUCTION If, by 1 December 2022, the total allowable catch of Antarctic krill ( I Euphausia superba i ) taken from the Scotia Sea (here, waters between 50-70°S and 20-70°W) (Figure 1) is not partitioned in space and time, the objective of an international conservation regime will be jeopardized. [Extracted from the article]

Poleward range shifts are a global‐scale response to warming, but these vary greatly among taxa and are hard to predict for individual species, localized regions or over shorter (years to decadal) timescales. Moving poleward might be easier in the Arctic than in the Southern Ocean, where evidence for range shifts is sparse and contradictory. Here, we compiled a database of larval Antarctic krill, Euphausia superba and, together with an adult database, it showed how their range shift is out of step with the pace of warming. During a 70‐year period of rapid warming (1920s–1990s), distribution centres of both larvae and adults in the SW Atlantic sector remained fixed, despite warming by 0.5–1.0°C and losing sea ice. This was followed by a hiatus in surface warming and ice loss, yet during this period the distributions of krill life stages shifted greatly, by ~1000 km, to the south‐west. Understanding the mechanism of such step changes is essential, since they herald system reorganizations that are hard to predict with current modelling approaches. We propose that the abrupt shift was driven by climatic controls acting on localized recruitment hotspots, superimposed on thermal niche conservatism. During the warming hiatus, the Southern Annular Mode index continued to become increasingly positive and, likely through reduced feeding success for larvae, this led to a precipitous decline in recruitment from the main reproduction hotspot along the southern Scotia Arc. This cut replenishment to the northern portion of the krill stock, as evidenced by declining density and swarm frequency. Concomitantly, a new, southern reproduction area developed after the 1990s, reinforcing the range shift despite the lack of surface warming. New spawning hotspots may provide the stepping stones needed for range shifts into polar regions, so planning of climate‐ready marine protected areas should include these key areas of future habitat. [ABSTRACT FROM AUTHOR]

Following the cessation of whaling, the southwest Atlantic humpback whale (Megaptera novaeangliae) population is thought to be close to pre-exploitation size, reversing 20th century changes in abundance. Using a model-based approach applied to concurrently collected data on baleen whale abundance and Antarctic krill (Euphausia superba) biomass in the South Sandwich Islands (SSI) region, we explore ecological interactions between these taxa. Krill biomass and baleen whale density were highest to the north and northeast of the SSI, where the Antarctic Circumpolar Current (ACC) is deflected around the island chain. Humpback whale density was elevated at locations of krill biomass density >150 gm-2. Krill consumption by baleen whales was estimated at 19–29% of the available krill standing stock. We used historic whaling data to confirm the plausibility of these consumption rates and found evidence of rapid weight gain in humpback whales, such that blubber depleted during the breeding season could be restored in a much shorter period than previously assumed. Little is known about krill replenishment rates in the flow of the ACC, or about niche separation between recovering baleen whale populations; both factors may affect species carrying capacities and further monitoring will be required to inform the management of human activities in the region. • Krill biomass density distribution was modelled using a two-stage Maxent/GLM process. • Humpback whale abundance and distribution was modelled using a GAM. • Whales consume 19–29% of available krill in the South Sandwich Islands region. • On southern feeding grounds humpback whales can rapidly restore depleted blubber. • Future studies on rates of krill transport in oceanographic currents will be important. [ABSTRACT FROM AUTHOR]