With continuing sea ice reductions in the Arctic, dynamic physical and ecological processes have more active roles compared to the ice-locked, isolated Arctic Ocean of previous decades. To better ...understand these changes, observations of high-resolution sea ice conditions are needed. Remote sensing is a useful tool for observations in the harsh Arctic environment. For unsupervised ice detection, we demonstrate the promising value of radar phase difference from polarimetric radar measurements in this study, based on full polarimetric complex RADARSAT-2 SAR images in the marginal ice zone. It is demonstrated that the phase difference from co-polarized and cross-polarized synthetic aperture radar (SAR) images show promising capability for high resolution sea ice discrimination from open water. In particular, the phase difference shows superior potential for the detection of frazil ice compared to the traditional methodology based on the radar intensity ratio. The relationship between phase difference and radar incidence angle is also analyzed, as well as the potential influence of high sea state. The new methodology provides an additional tool for ice detection. In order to make the best use of this tool, directions for further studies are discussed for operational ice detection and possible ice classification.
Pathogen dispersal from infected aquaculture sites into the surrounding ocean poses risks of infection to wild and farmed species, but is difficult to predict. This study aimed to build a framework ...using an ocean circulation and a particle tracking model in conjunction with a dynamic infection model and a virus inactivation model to simulate the dispersal of the infectious salmon anemia virus (ISAV) from Atlantic salmon farms. Simulated particles were released from hypothetically infected farms and advected by modelled currents. Inactivation of viral cohorts by ambient ultraviolet radiation and natural microbial communities was simulated during advection. Simulations showed that ISAV concentration varied spatiotemporally with the progression of the outbreak, current speed and direction, tidal elevation amplitude, and environmental decay. Connectivity among aquaculture sites varied in relation to seaway distances, though simulations showed that connectivity can also be asymmetrical between farm sites. Sensitivity analyses showed that the dispersal of ISAV was moderately sensitive to uncertainty associated with the viral decay model, highlighting the importance of obtaining accurate estimates of inactivation rates of ISAV. This framework provides an approach to simulate waterborne viral transmission that considers the biology and epidemic features of significance for pathogens and the dynamic conditions of the ocean.
The study was designed to explore the effect of vaccinating turbot broodstocks on the immunity of offsprings. The expression of IgM, C3, TGF-β1, IL-1β, transferrin, lysozyme and their concentrations ...were detected respectively with quantitative real-time PCR and Elisa kits in offsprings at different stages from both naive and vaccinated brood stocks. The survival rate of offsprings in pathogen challenge experiment and their pathogen inhibition rate were also detected. The results shown that the maternal transfer of genes and proteins both existed in turbot. In the expression level, from eggs to 5 dpf (days past fertilization), the immune related genes expressed far more in vaccinated broodstocks offsprings, after hatching, the phenomenon disappeared. In protein level, transferrrin, C3 and IL-1β kept a stable level in concentration from eggs to 25 dph (days past hatching), and increased sharply at 45 and 55 dph. While, IgM and lyzozyme had a much higher concentration at 5 dpf in the embryos from vaccinated broodstocks, and we concluded that vaccinating broodstocks enhanced the production or maternal transfer of IgM and lyzozyme. Vibrio anguillarum challenge experiment showed that the vaccinated offsprings of 4 dpf and 14 dph had a better anti-pathogen ability than the ones from naive brood stocks. Throughout the study, it was concluded that vaccinating broodstocks could strength the maternal transfer of immune factors in gene and protein level, and the gene expression level during hatching was also enhanced at the early stage of development.
•The maternal transfer of immune genes and proteins both exists in turbot.•Vaccinating brood stocks before spawning seasons could enhance the maternal transfer effect.•The enhancing effect of vaccinating focused on the hatching process.•Different kinds of immune factors have different variations during the experiment.
Development of Atlantic halibut (
Hippoglossus hippoglossus) aquaculture will be enhanced with cryopreservation of halibut sperm by ensuring a reliable supply of sperm of desired quality and ...quantity. To assist in its commercial application, the cryopreservation of large volumes of halibut sperm was investigated. Three cryoprotectants were compared: dimethyl sulfoxide (DMSO), polyethylene glycol (PG) and glycerol (GLY) at two concentrations (10% or 15%). Two salt solutions, Hanks’ balanced salt solution (HBSS) and 0.1
M KHCO
3 with 0.125
M sucrose solution (KS) were tested as diluents. Both factors were examined in 1.6
mL volumes. A cryopreservation volume of 4
mL and a low dilution ratio (1:1) were examined separately. Based on motility and fertilization rate, 10% and 15% DMSO diluted with HBSS or KS solution proved to be effective extenders with mean fertilization rates ranging from 52.2
±
27.2% to 65.8
±
26.1%; none of which were significantly different from that of the control. Four other extenders, 10% PG or 10% GLY with HBSS or KS, resulted in significantly lower fertilization rates. Use of a 4
mL cryopreservation volume did not exhibit a significant effect on fertilization rate or motility of post-thawed sperm compared to a 1.6
mL volume (
P
>
0.05); while the use of a dilution ratio of one part sperm with three parts cryopreservation solution (1:3 v/v with sperm concentration of 0.51
±
0.11
×
10
10
cells/ml) had a significantly better preservation effect than using a ratio of 1:1 with sperm concentration of 1.02
±
0.21
×
10
10
cells/ml (
P
<
0.05). From these results, an optimized protocol for the cryopreservation of Atlantic halibut sperm using a volume as large as 4
mL has been established.
In this research, the concentration and activity of oxidants and anti-oxidants in turbot semen, and their effects on sperm quality were studied. The results showed that superoxide dismutase （SOD）, ...catalase, glutathione reductase （GR）, uric acid, vitamin E （VE） and vitamin C （Vc） were more abundant in seminal plasma than in spermatozoa. The variation for each of them was specific. In seminal plasma, the activity of SOD and GR increased from November 15, November 30 to December 15, and then decreased on December 30. The concentrations of both Vc and uric acid decreased during the first 3 sampling times and increased on December 30 The oxidants in seminal plasma accumulated to the highest on December 30. Lactic acid （LA） and ATP levels decreased to the low- est on December 30. The correlation analysis showed that GR had the significant positive relevance to sperm motility and VSL/VCL, while .OH had negative relevance to them.
Hormone implantation is widely applied in halibut (Hippoglossus hippoglossus L.) aquaculture to extend the sperm production season of broodstock males. The ability to combine this technique with ...cryopreservation would increase sperm availability, thereby improving reproduction success and facilitating gene management. In this paper, the cryopreservation ability of sperm from hormone-treated males was examined at three times post-implantation and compared with that of sperm from males that were not hormone-treated. All sperm samples were cryopreserved using the same method. The effectiveness of these techniques was assessed by examining the fertilization rate and motility of thawed sperm. The spermotocrit and concentration of fresh sperm samples were measured to reveal the effect of hormone implantation on sperm characteristics. The reported results indicate that hormone implantation did not affect cryopreservation efficiency. The fertilization rate resulting from thawed sperm of hormone-treated males showed no significant difference from that of untreated males or from fresh sperm. A significant positive relationship was demonstrated between the spermatocrit and concentration of sperm; and a significant decrease of spermatocrit was found in sperm collected from hormone-treated males 14days post-implantation. No significant linear relationship between spermotocrit and fertilization rate of thawed sperm was shown.
Recovered archival satellite tags afford a rare opportunity to evaluate diving behavior relative to ocean conditions at fine spatiotemporal scales. Ocean temperature and mixed layer depth (MLD) were ...strongly related to daily and seasonal patterns in diving behavior of an adult female porbeagle shark Lamna nasus. The shark remained below MLD when waters were strongly stratified in summer or in the Gulf Stream; the daily timing of dives was associated with local sunrise and sunset. In the presence of a hurricane, diving activity abruptly increased, coincident with upwelling causing an abrupt decrease in surface temperature. Our first report of the behavioral response to a hurricane as well as the seasonal patterns in depths, occupied temperatures, and vertical speeds suggest environmental preferences of porbeagle are not static and individuals may use horizontal, as well as vertical, movement to take advantage of areas with specific characteristics.
Aquaculture farm cages have the ability to interact with local circulation due to the drag caused by the cages. We examined how the drag influences the residence time of particles within fish farms ...in the southwest Isles region of New Brunswick, Canada, in the Bay of Fundy using a high-resolution hydrodynamic model. To accomplish this, we parameterized the cage drag in the model and modeled flow structures at multiple spatial scales, ranging from several meters within the cages, to tens of kilometers in the adjacent open ocean. We used models with and without cage drag to demonstrate how residence time was influenced by the imposition of the cage infrastructure. Our examination indicated that the drag produced by cages is able to significantly change the residence time of particles. The magnitude of the change is strongly sensitive to the timing of tides, tidal speeds and specific locations of farms. Our results suggest that the flushing properties of the wastes from aquaculture activities—for example, feed and subsequently fecal material—are strongly related to flow properties and their interactions with cages. These results emphasize that the design of fish farms should explicitly account for the influence of physical infrastructure (i.e. cages) on depositional processes in order to try and minimize environmental effects.
The aim of this study was to optimize the cryopreservation protocols for the sperm of red seabream, Pagrus major. The 2‐mL cryovials and programmable freezer were employed for cryopreservation. Six ...extenders, six cryoprotectants in various concentrations ranging from 6 to 20% (v/v), four cooling rates, and three thawing temperatures were evaluated by postthaw sperm motility and fertility. The ratio of sperm to egg for postthaw sperm fertilization trials was experimentally standardized and was optimal at 500:1. The best motility of postthaw sperm (79.4 ± 4.7% to 88.6 ± 8.0%), fertilization rates (89.6 ± 2.9 to 95.6 ± 1.9%), and hatching rates (85.3 ± 5.1% to 91.4 ± 4.3%) were achieved when Cortland extender, dimethyl sulfoxide (15, 18, and 20%) or ethylene glycol (9, 12%) as cryoprotectants, 20 C/min as the cooling rate, and 40 C as the thawing temperature were employed. Moreover, the results on embryonic development were not significantly different between cryopreserved sperm and fresh sperm during incubation process. In conclusion, these methods of cryopreservation of red seabream sperm are suitable for routine aquaculture application and preservation of genetic resources.
Previous studies have revealed the effect of set size (the number of activated items) on object switching in working memory, but the underlying neural mechanism remains unclear. In this study, ...participants were asked to first remember two (small size) or three (large size) two‐digit numbers and the corresponding geometrical figures as different references for numerical comparison and then compare a series of numbers (10–99) to the reference numbers cued by different geometrical figures. The cue repeated or switched across trials. Behavioral results revealed that the switch cost was greater in the large‐size condition than in the small‐size condition. Event‐related potential results showed that in the N2 component, an interaction was observed between set size and transition, with a significant transition effect (switch minus repeat) in the large‐size condition and a non‐significant transition effect in the small‐size condition. The same interaction was observed in the P3 component, with a larger amplitude difference (switch minus repeat) in the large‐size condition than in the small‐size condition. These results suggested that when set size is increased, the effort to inhibit the irrelevant items increases, resulting in large cost of object switching in working memory.
In the first ERP study of the neural mechanisms underlying the effect of set size on the cost of object switching in working memory, we showed that the effect of memory set size on switch cost is mirrored in brain potentials in the N2 and P3 components, with a larger amplitude difference (switch minus repeat) in large‐size than small‐size condition, reflecting increased selective inhibition of irrelevant items.
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