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Volume 37 ， Issue 5 ， 2019
- Abstract：In this study, high-resolution temperature and salinity data obtained from three Sea-Wing underwater gliders were used together with satellite altimeter data to track the vertical thermohaline structure of an anticyclonic eddy that originated from the loop current of the Kuroshio southwest of Taiwan, China. One of the gliders crossed the entire eddy and it observed a remarkable warm anomaly of as much as 3.9℃ extending to 500 dbar from the base of the mixed layer. Conversely, a positive salinity anomaly was found to be above 200 dbar only in the anticyclonic eddy, with a maximum value of >0.5 in the mixed layer. Below the mixed layer, water of higher salinity (>34.7) was found, which could have been preserved through constrained vertical mixing within the anticyclonic eddy. The salinity in the upper layer of the anticyclonic eddy was much similar to that of the northwestern Pacific Ocean than the northern South China Sea, reflecting Kuroshio intrusion with anticyclonic eddy shedding from the loop current.Keywords：Anticyclonic Eddy;South China Sea;Kuroshio;Sea-Wing underwater glider5|2|11Updated：2023-05-20
- Abstract：Data from satellite altimetry and in situ observations together with the Hybrid Coordinate Ocean Model (HYCOM) reanalysis data were used to investigate the mechanism and formation of an anticyclonic eddy in the northeastern South China Sea (SCS). Analysis of water mass using cruise data indicated that the water captured in the eddy differs from those in the SCS, the Kuroshio intrusion, and the eddy-forming region. Data from sea surface height (SSH) and sea level anomaly (SLA) indicate that the eddy formed due both to the Kuroshio intrusion and the local circulation in the SCS. The Kuroshio intrusion is present at the start of the eddy growth (March 5-9) before Kuroshio leaps the Luzon Strait. The eddy then becomes larger and stronger in the absence of the Kuroshio intrusion. From the eddy budget of the HYCOM reanalysis data, the formation of the eddy goes in three steps. By the third step, the eddy had become affected by variations of local SCS circulation, which is more strongly than in the first step in which it is affected more by the Kuroshio intrusion. The variability of the temperature and salinity inside the eddy provide a support to this conclusion. The water in the SCS intruded into the eddy from the southeast, which decrease the salinity gradually in the southern part of the eddy during the growth period.Keywords：Anticyclonic Eddy;Kuroshio intrusion;circulation variation;water mass4|2|1Updated：2023-05-20
- Abstract：The decadal variations of the North Pacific Tropical Water (NPTW) at 137°E in the western North Pacific Ocean are investigated based on the repeated hydrographic observations along with two global gridded ocean products. The results indicate that the maximum salinity of NPTW experiences significant quasi-decadal variations, having maxima around 1979, 1987, 1995, 2004, and 2012, while minima around 1974, 1983, 1991, 1999, and 2008 during the period of interest. The NPTW area also shows similar quasidecadal variation, expanding/shrinking as its maximum salinity increases/decreases at the 137°E section. These variations are induced mainly by changes in the mixed layer salinity in the source region and largescale circulation in the northwestern tropical Pacific Ocean, both of which are related to the Pacific Decadal Oscillation. The underlying processes at work are further confirmed through conducting the subsurface salinity budget analysis. Besides, short-term processes are also at work through nonlinear interactions, especially after 2000.Keywords：North Pacific Tropical Water (NPTW);decadal variation;subsurface salinity budget;Pacific Decadal Oscillation4|3|0Updated：2023-05-20
- Abstract：Studies on climate change typically consider temperature and precipitation over extended periods but less so the wind. We used the Cross-Calibrated Multi-Platform (CCMP) 24-year wind field data set to investigate the trends of wind energy over the South China Sea during 1988-2011. The results reveal a clear trend of increase in wind power density for each of three base statistics (i.e., mean, 90th percentile and 99th percentile) in all seasons and for annual means. The trends of wind power density showed obvious temporal and spatial variations. The magnitude of the trends was greatest in winter, intermediate in spring, and smallest in summer and autumn. A greater trend of increase was found in the northern areas of the South China Sea than in southern parts. The magnitude of the annual and seasonal trends over the South China Sea was larger in extreme high events (i.e., 90th and 99th percentiles) compared to the mean conditions. Sea surface temperature showed a negative correlation with the variability of wind power density over the majority of the South China Sea in all seasons and annual means, except for winter (41.7%).Keywords：wind energy;Cross-Calibrated Multi-Platform (CCMP) wind field;South China Sea;temporal and spatial variation4|1|1Updated：2023-05-20
- Abstract：The maritime administrative department employs synthetic aperture radar (SAR) satellite remote sensing technology to obtain evidence of illegal discharge of ships. If the ship is discharged during navigation, it forms a long dark wake on the SAR image due to the suppression of the Bragg wave by the oil film. This study investigates key techniques for rapid detection of long ship wakes, thereby providing law enforcement agencies with candidate ships for possible discharge. This paper presents a rapid long ship wake detection method that uses satellite imaging parameters and the axial direction of the ship in images to determine the potential detection area of the wake. Then, the threshold of long ship wake detection is determined using statistical analysis, the area is binarized, and isolated points are removed using a morphological filter operator. The method was tested with ENVISAT Synthetic Aperture Radar and GF-3 SAR data, and results showed that the method was effective, and the overall accuracy of the decision reaches 71%. We present two innovations; one is a method that draws a Doppler shift curve, and uses the SAR imaging parameters to determine the detection area of the long wake to achieve rapid detection and reduce the image detection area. The other is where a classical linear fitting method is used to quickly and accurately determine whether the detected dark area is a long ship wake and realizes the twisted long ship wake detection caused by the sea surface flow field, which is otherwise difficult to detect by the traditional Radon and Hough transform methods. This method has good suppression performance for the dark spot false alarm formed by low speed wind region or upward flow. The method is developed for maritime ship monitoring system and will promote the operational application of maritime ship monitoring system.Keywords：marine pollution;illegal discharge;linear fit;oil spill;synthetic aperture radar (SAR);long ship wake4|2|3Updated：2023-05-20
- Abstract：GPS buoy methodology is one of the main calibration methodologies for altimeter sea surface height calibration. This study introduces the results of the Qinglan calibration campaign for the HY-2A and Jason-2 altimeters. It took place in two time slices; one was from August to September 2014, and the other was in July 2015. One GPS buoy and two GPS reference stations were used in this campaign. The GPS data were processed using the real-time kinematic (RTK) technique. The final error budget estimate when measuring the sea surface height (SSH) with a GPS buoy was better than 3.5 cm. Using the GPS buoy, the altimeter bias estimate was about -2.3 cm for the Jason-2 Geophysical Data Record (GDR) Version 'D' and from -53.5 cm to -75.6 cm for the HY-2A Interim Geophysical Data Record (IGDR). The bias estimates for Jason-2 GDR-D are similar to the estimates from dedicated calibration sites such as the Harvest Platform, the Crete Site and the Bass Strait site. The bias estimates for HY-2A IGDR agree well with the results from the Crete calibration site. The results for the HY-2A altimeter bias estimated by the GPS buoy were verified by cross-calibration, and they agreed well with the results from the global analysis method.Keywords：HY-2A altimeter;calibration;GPS buoy;sea surface height;Jason-2 altimeter4|0|7Updated：2023-05-20
- Abstract：The absorption spectrum of phytoplankton is an important bio-optical parameter for ocean color hyperspectral remote sensing; its magnitude and shape can be affected considerably by pigment composition and concentration. We conducted Gaussian decomposition to the absorption spectra of phytoplankton pigment and studied the spectral components of the phytoplankton, in which the package effect was investigated using pigment concentration data and phytoplankton absorption spectra. The decomposition results were compared with the corresponding concentrations of the five main pigment groups (chlorophylls a, b, and c, photo-synthetic carotenoids (PSC), and photo-protective carotenoids (PPC)). The results indicate that the majority of residual errors in the Gaussian decomposition are < 0.001 m-1, and R2 of the power regression between characteristic bands and HPLC pigment concentrations (except for chlorophyll b) was 0.65 or greater for surface water samples at autumn cruise. In addition, we determined a strong predictive capability for chlorophylls a, c, PPC, and PSC. We also tested the estimation of pigment concentrations from the empirical specific absorption coefficient of pigment composition. The empirical decomposition showed that the Ficek model was the closest to the original spectra with the smallest residual errors. The pigment decomposition results and HPLC measurements of pigment concentration are in a high consistency as the scatter plots are distributed largely near the 1:1 line in spite of prominent seasonal variations. The Woźniak model showed a better fit than the Ficek model for Chl a, and the median relative error was small. The pigment component information estimated from the phytoplankton absorption spectra can help better remote sensing of hyperspectral ocean color that related to the changes in phytoplankton communities and varieties.Keywords：phytoplankton absorption spectrum;pigment concentration;Gaussian decomposition4|1|3Updated：2023-05-20
Physics
- Abstract：Outbreaks of large-scale green tides formed by Ulva prolifera in the Yellow Sea (YS) cause heavy ecological damages and huge economic losses. However, the ecological consequences of green tides remain poorly understood due to the lack of knowledge on the settlement region of massive green algae floating in the YS. In this study, we established a method to trace the settlement region of floating green algae, using 28-isofucosterol preserved in sediment as the specific biomarker for green algae. Sterols including 28-isofucosterol in surface sediment samples collected during an investigation in the YS and the Bohai Sea (BS) in August 2015 were analyzed using gas chromatography coupled with a mass spectrometer (GC-MS). Based on the content of 28-isofucosterol in sediment samples, the potential settlement region of floating green algae was identified in the sea area southeast to the Shandong Peninsula around the sampling site H06 (122.66°E, 36.00°N). This paper presents a first result on the settlement region of floating green algae in the YS for providing a solid basis to elucidate the ecological consequences of green tides in the area.Keywords：green tide;biomarker;sterol;Ulva prolifera4|0|8Updated：2023-05-20
- Abstract：Carbonyl compounds, especially polyunsaturated aldehydes (PUAs), are increasingly reported as teratogenic to grazers and deleterious to phytoplankton. While PUAs have been considered to be mainly produced by diatoms after cell wounding, little is known about whether microalgae other than diatoms, particularly harmful algal bloom (HAB)-forming species, produce carbonyl compounds. In this study, we analyzed the carbonyl compounds from eight common HAB-forming species (Akashiwo sanguinea, Karenia mikimotoi, Karlodinium veneficum, Margalefidinium polykrikoides, Prorocentrum donghaiense, P. minimum, Scrippsiella trochoidea, and Heterosigma akashiwo) using gas chromatography-mass spectrometry in full scan and selected ion monitoring (SIM) modes. Our results show a ubiquitous presence of carbonyl compounds in both dissolved and particulate forms in all species we examined. In the full scan mode, 133 chromatographic peaks were detected from 51 samples altogether. Both the varieties of carbonyl compounds and their quantities were algal species dependent, although most of the carbonyl compounds could not be fully identified according to the mass spectral database only due to the unavailability of enough standards for all analytes. Aided with nine standards in SIM mode, we further identified and quantified all nine aldehydes (2-methyl-2-pentenal, trans-2-nonenal, cis-6-nonenal, 2, 6-dimethyl-5-heptenal, trans-2-hexenal, trans-2-decenal, 2, 4-heptadienal, trans-trans-2, 4-octadienal, and trans-trans-2, 4-decadienal). Four of these nine aldehydes were detected in particulate form, which confirmed that trans-2-nonenal could be produced by K. mikimotoi, Karl. veneficum, P. donghaiense, P. minimum, S. trochoidea, and H. akashiwo, 2, 4-heptadienal and trans-trans-2, 4-decadienal by A. sanguinea, M. polykrikoides, and S. trochoidea, and trans, trans-2, 4-octadienal by S. trochoidea, respectively. We proved that some dinoflagellate and raphidophyte species could contribute to the pool of carbonyl compounds including PUAs in a marine ecosystem. Some carbonyl compounds, particularly those in high cell quota and/or dissolved concentration, may be related to fishkilling or allelopathy which needs further identification and quantification.Keywords：aldehyde;dinoflagellate;harmful algal blooms (HABs);heptadienal;octadienal;decadienal4|3|0Updated：2023-05-20
- Abstract：Increasing numbers of approaches to assess eutrophication, such as estuarine trophic status, the Oslo-Paris Commission Common Procedure, and the Water Framework Directive, focus on the symptoms of eutrophication. In China, however, nutrient index methods dominate the assessment of coastal waters. In this study, an integrated method that includes both water quality and ecological response was compared with the Northwest Pacific Action Plan (NOWPAP) Common Procedure. Observation data from Jiaozhou Bay, Shandong, China, were used in a comparison of the two methods in a trophic status study. Overall, both clearly revealed a high level of nutrient enrichment in the bay, indicated by high nutrient concentrations. Though the two methods differed in their methodological design in the assessment of the ecological effects of nutrient enrichment, they have acquired similar results:the integrated method suggested that the status was good, and the NOWPAP Common Procedure suggested that the status was low (indicating that the bay had no serious eutrophication problem). The introduction of filter feeders (shellfish aquaculture) into the bay on a reasonable scale may have been effective in mitigating eutrophic conditions, and perhaps explains the low ecological impacts there. Our results will be useful to ecosystem-based eutrophication management in the bay and in similar areas.Keywords：eutrophication assessment;integrated methodology;Northwest Pacific Action Plan (NOWPAP) Common Procedure;Jiaozhou Bay4|2|1Updated：2023-05-20
- Abstract：Octopus minor is widely distributed along the northern coast of China. To date, there is little information on the prey selection process of this species. To understand this process, several experiments were carried out. Three types of bivalves, namely, Ruditapes philippinarum, Mactra chinensis, and Mytilus galloprovincialis, were used to observe the prey selection of O. minor and to analyze the potential causes of prey selection from three aspects:prey profitability, adductor muscle tension and handling time. Under single-prey conditions, we found that the average (±SD) predation rates of O. minor on R. philippinarum, M. chinensis, and M. galloprovincialis were 1.73±0.50, 1.27±0.42, and 0.8±0.2/d, respectively. Under different prey combinations, octopods actively selected one type of prey over the other(s), and the order of prey preference was R. philippinarum, followed by M. chinensis and lastly M. galloprovincialis. Furthermore, the shells of the consumed prey showed that O. minor only consumed bivalves by pulling them apart since there was no evidence of drill holes on the shells. The prey selection of O. minor was related to the prey profitability and handling time; O. minor appeared to select preys with a higher profitability and a shorter handling time. However, the difficulty in opening the bivalve was not consistent with the prey preference of the octopods. These results suggest that O. minor prefers to consume R. philippinarum possibly due to a high profitability and a short handling time that supports the optimum Foraging Theory.Keywords：Octopus minor;bivalve;prey preference;prey selection;prey profitability4|0|4Updated：2023-05-20
- Abstract：Maternal effects are one of the most interesting topics in evolutionary ecology as they can affect the rate of evolution and population dynamics by phenotypic manipulation of offspring related to fitness. At present, studies examining the interaction between maternal environment effects and maternal age (birth order) effects are scarce. We designed an experiment to reveal whether environmentally induced maternal manipulation works equally on offspring across birth orders in rotifer Brachionus calyciflorus. In the experiment, newborn amictic mothers (F0) were cultured parallelly in low (LD) and high (HD) population density. Offspring (F1) of young (YF0) and old (OF0) mothers in both LD and HD groups were cultured under a crowded condition and the mixis ratios of both F1 and F2 were examined. Results show that F1 from HD-YF0 had a significantly higher mixis ratio and those amictic ones produced daughters (F2) with higher mixis ratio in response to crowding than those from HD-OF0. In contrast, no such differences among F1 siblings were found in the LD-F0 group. Therefore, the effect of maternal age on the sexual propensity of the offspring can be affected independently by the maternal population density.Keywords：rotifer;Brachionus calyciflorus;sexual propensity;birth order effect;maternal environment;mixis ratio4|0|0Updated：2023-05-20
- Abstract：To better understand the spatial-temporal variation in phytoplankton community structure and its controlling factors in Jiaozhou Bay, Qingdao, North China, four seasonal sampling were carried out in 2017. The phytoplankton community structure and various environmental parameters were examined. The phytoplankton community in the bay was composed of mainly diatoms and dinoflagellates, and several other species of Chrysophyta were also observed. Diatoms were the most dominant phytoplankton group throughout the year, except in spring and winter, when Noctiluca scintillans was co-dominant. High Si/N ratios in summer and fall reflect the high dominance of diatoms in the two seasons. Temporally, the phytoplankton cell abundance peaked in summer, due mainly to the high temperatures and nutrient concentrations in summer. Spatially, the phytoplankton cell abundance was higher in the northern part of the bay than in the other parts of the bay in four seasons. The diatom cell abundances show significant positive correlations with the nutrient concentrations, while the dinoflagellate cell abundances show no correlation or a negative correlation with the nutrient concentrations but a significant positive correlation with the stratification index. This discrepancy was mainly due to the different survival strategies between diatoms and dinoflagellates. The Shannon-Wiener diversity index (H') values in the bay ranged from 0.08 to 4.18, which fell in the range reported in historical studies. The distribution pattern of H' values was quite different from that of chlorophyll a, indicating that the phytoplankton community structure might have high biomass with a low diversity index. Compared with historical studies, we believe that the dominant phytoplankton species have been changed in recent years due mainly to the changing environment in the Jiaozhou Bay in recent 30 years.Keywords：phytoplankton;community structure;environmental parameter;seasonal variation;cell abundance;Jiaozhou Bay4|2|7Updated：2023-05-20
- Abstract：Decreasing fish resources in estuaries is a subject of anthropogenic activities. Studies of the spatiotemporal distribution of fish eggs and larvae can help identify the status and processes underlying recruitment in a fishery. As the fifth largest river estuary in the world, the Huanghe (Yellow) River estuary (HRE) is a typical estuary that has been seriously affected by human activities. Annual surveys on ichthyoplankton and environmental factors were conducted in the months of May of 2005 and 2009-2016 in the HRE to investigate the spatiotemporal distribution of fish eggs and larvae and the associated influencing factors. A total of 23 and 20 species of eggs and larvae, respectively, were collected. The dominant orders were Perciformes (51.2%) and Clupeiformes (25.6%). The average number of fish species eggs and larvae were 6.0 and 4.1 in average abundance of 0.91 and 0.13 ind./m3, respectively. The dominant species were mainly low-commercial-value small-sized fishes, such as Clupanodon punctatus, Harengula zunasi, and Acanthogobius, whereas certain traditional commercial fishes, such as Trichiurus lepturus, and Clupea pallasii, were not seen. Analysis of the fish egg and larval community revealed four temporal assemblages and two spatial assemblages. Salinity was the main factor on the spatial distribution of ichthyoplankton communities, the species number and Shannon-Weiner diversity index (H') of the fish egg and larval community near the river mouth with lower salinity were significantly lower than the community far away from the river mouth with higher salinity. In addition, increases of water temperature promoted the number and abundance of fish species eggs, and the areas of abundant prey tended to have a more diversified and abundant of ichthyoplankton species. In overall, overfishing, dam construction, and other human activities were the main drivers that led to the substantial decline in fishery resources in the HRE.Keywords：Huanghe (Yellow) River estuary;fish egg and larva;environmental factors;fishery resources;human activity4|1|4Updated：2023-05-20
Ecology
- Abstract：We investigated the bacterioplankton abundance, community composition and the associated Vibrio clades of natural seawater in Bohai Sea coastal waters. Seawater samples (10 L in triplicate) were collected at 0.5, 3, and 5 m depths near the coastal aquaculture zone of the Bohai Sea on May 12, 2016. Real-time PCR and 16S rRNA gene amplicon high-throughput sequencing methods were employed by which 485 operational taxonomic units (OTUs) at a 97% sequence similarity level were generated. Gammaproteobacteria, Alphaproteobacteria, and Bacteroidetes were the most abundant groups, accounting for 49.5%, 23.5%, and 18.9% of the total assemblage, respectively. Obvious variations in Pseudoalteromonas, Vibrio, and Octadecabacter, which were the most abundant genera, could be observed among different samples. Notably, the results of Vibrio-specific real-time PCR indicated that Vibrio had extremely high 16S rRNA gene copy numbers. The 16S rRNA gene sequencing results across all the samples also indicated that they occupied a large proportion of the total assemblage. Both the alpha diversity and major bacterioplankton group Pseudoalteromonas had significant correlations with the concentration of PO43-. Overall, studies on bacterioplankton communities with highly abundant Vibrio clades can provide interesting insight into the microbial function and health assessment of the Bohai Sea coastal ecosystem.Keywords：Bohai Sea;bacterioplankton;Vibrio;16s rRNA;Illumina MiSeq4|0|0Updated：2023-05-20
- Abstract：Innexin proteins are a class of transmembrane proteins existing in invertebrates and they have diverse biological functions. The innexin protein Sp-inx2 has been demonstrated to play roles in immune response and promotion of cell apoptosis in the mud crab Scylla paramamosain. One novel innexin gene, named as Sp-inx3 was characterized from S. paramamosin in this study, with an open reading frame of 1 101 bp encoding 367 amino acid residues. Multiple sequence alignment revealed that the Sp-inx3 is highly homologous with innexin3 of Cancer boredis and Homorus americanus. Quantitative real-time PCR (qPCR) and the western blotting results revealed that Sp-inx3 gene was expressed predominantly in the eyestalk, brain, and thoracic ganglion mass in both female and male crabs. The immunohistochemistry assay (IHC) also showed the widespread and intense immunoreactivity of Sp-inx3 in the brain and thoracic ganglion mass. Sp-inx3 mRNA transcription profiles exhibited significantly higher expression from the embryo1 to embryo4 period and low level of expression at the prehatching period and zoea I larva period of S. paramamosain. These results indicate that the Sp-inx3 may play an important role in the nervous system and early embryonic development of S. paramamosain.Keywords：Scylla paramamosain;Sp-inx3;gene expression;embryonic development;nervous system4|0|0Updated：2023-05-20
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iTRAQ-based analysis of 17β-estradiol induced proteome in Chinese tongue sole
Cynoglossus semilaevis Abstract：The phenomenon of sex dimorphism prevails among many fish species. It has attracted the general research interest due to its close relationship to fish growth and thus aquaculture productivity. In Chinese tongue sole (Cynoglossus semilaevis), 17β-estradiol (E2) can be used reportedly to induce the feminization of fish, although the detailed regulatory network remained elusive. We treated the tongue sole fry before sex differentiation with E2 (10 and 30 μg/L) to identify potential targets of E2 in Chinese tongue sole. The E2 treatment indeed induced genetic male fish sex-reversal to phenotypic female. Using an iTRAQ-based comparative proteomic analysis, 409 proteins that differentially expressed after E2 induction were identified, including 259 up-regulated and 150 down-regulated proteins. Furthermore, 19 differentially expressed proteins identified in the comparative proteomic analysis were selected to assess their transcription and eight of them exhibited the same tendency. Functions of the eight proteins included mainly nucleotide and protein binding. Interestingly, a far upstream element-binding protein 3-like isoform exhibited the significant upregulation both at transcription and translation levels after E2 treatment. This work identified a set of candidate proteins for E2 response and deepened our understanding of E2 regulatory mechanism.Keywords：Cynoglossus semilaevis;17β-estradiol;sex reversal;proteome;iTRAQ analysis4|0|0Updated：2023-05-20 - Abstract：The brine shrimp Artemia exhibits two reproductive modes:1) oviparity, producing diapause embryos; and 2) ovoviviparity, producing free-swimming nauplii. Previous studies have suggested the existence of a critical stage that determines the reproductive mode. Physicochemical factors, such as photoperiod, temperature, and salinity, have been suggested to irreversibly affect the reproductive mode of oocytes during this critical stage. In this study, experiments were carried out using a photoperiod and temperature-sensitive parthenogenetic Artemia clone where maternal Artemia were shifted bidirectionally between ovoviviparity (18 h L:6 h D, 27℃) and oviparity (6 h L:18 h D, 19℃) culture conditions. In the main experiment (Artemia shifted at six different stages including the post-larva Ⅱ to adult Ⅱ), the reproductive mode of first brood was converted when shifting was performed on post-larva Ⅱ and Ⅲ but was not converted when females were shifted after post-larva Ⅲ. A supplementary experiment further revealed that the reproductive mode of first brood could be altered when shifting females at an "early phase of postlarva Ⅳ", characterized by a developing ovisac reaching the middle of the third abdominal segment, ventral spines, and some oocytes growing larger than the others. In both experiments, reproductive modes of the second brood were significantly affected when the shifting was performed on post-larva Ⅳ. These results suggest that the critical stage for inducing oviparity and embryonic diapause is at the previtellogenic stage of oocytes, or at maternal "early phase of post-larva Ⅳ" for the first-brood offspring. During this stage, differential gene expression patterns of the two destined oocytes may be triggered by the token stimuli signals received by the oocytes.Keywords：Artemia;reproduction mode;environmental factors;diapause;critical stage;Anostraca4|0|0Updated：2023-05-20
- Abstract：Phycocyanin (PC), a natural algal protein, is reported for having anti-oxidant and antiinflammatory properties. We investigated its ability to attenuate lung inflammation in mice subjected to X-ray radiation. Male C57BL/6 mice were assigned to the control, total body irradiation, PC pretreatment, and PC treatment groups. Mice in the PC pretreatment group were gavaged with 200 mg/kg PC for 7 consecutive days before irradiation, and those in the PC treatment group were gavaged with 200 mg/kg PC for 7 consecutive days after irradiation. Lungs were collected on Day 7 after irradiation exposure. Hematoxylin and eosin staining of mouse lung sections showed considerable inflammation damage 7 days after irradiation compared with the control lung but a reduction in pathological injury in the PC treatment group. Pretreatment or treatment with PC significantly decreased levels of interleukin-6 and tumor necrosis factor-α in the lung, and also increased the relative mRNA expression of superoxide dismutase and glutathione. In vivo, PC significantly reduced the expression of Toll-like receptor TLR2, myeloid differentiation primary response Myd88, and nuclear factor NF-κB, at both the transcriptional and translation level. Taken together, these data indicated that PC attenuated lung inflammatory damage induced by radiation by blocking the TLR2-MyD88-NF-κB signaling pathway. Therefore, PC could be a protective agent against radiation-induced inflammatory damage in normal tissues.Keywords：phycocyanin;inflammatory;TLR2-MyD88-NF-κB signaling pathway4|3|1Updated：2023-05-20
- Abstract：Clibanarius, a genus of hermit crabs, is one of the most diverse genera within Diogenidae. However, studies on the phylogeny withinClibanariusis very limited. We reconstruct the molecular phylogeny of the genus Clibanarius based on two mitochondrial (16S rRNA and COI) and two nuclear protein-coding (NaK and PEPCK) genes using a multigene phylogenetic approach. Eleven selected Clibanarius species from the Indo-West Pacific are analyzed and the Bayesian and maximum likelihood analyses produced identical results in topology. Results suggest that C. rutilus and C. infraspinatus are more closely related to each other than to C. snelliusi, and C. striolatus shows a close relationship to C. longitarsus. The close association of C. merguiensis with C. englaucus and C. humilis is strongly supported by the divergence of C. virescens from them. Our phylogenetic results contradict the morphological classification scheme proposed for Clibanarius and indicate that the relative length of dactyls and propodi is not phylogenetically significant in Clibanarius. In addition, we speculate that the morphological characteristic of the median cleft of the telson might be phylogenetically important for Clibanarius.Keywords：Clibanarius;phylogeny;molecular;evolution4|0|0Updated：2023-05-20
- Abstract：A new species belonging to the genus Haloschizopera Lang, 1944 (Copepoda, Harpacticoida, Miraciidae, Diosaccinae) was identified based on the samples collected from the East China Sea, near the offshore of Zhejiang Province, East China. The new species is closely related to H. pygmaea Norman & Sccot T., 1905 and shares a combination of the following features:A1 eight-segmented; A2 exp-2 with one distal seta, exp-3 with three setae; P1 endopodal segments subequal, enp-1 not exceeding exp-2; exp-3 of P3 with one inner seta, of P4 with two inner setae. The new species is characterized by the presence of one inner seta on P2 exp-3 of both sexes. It can also be distinguished from its congeners by the characters of female:P5 exopod subcircular, endopodal lobe extending beyond half-length of exopod; genital doublesomite ornamented with three dorsolateral rows of spinules on anterior part.Keywords：meiobenthos;new species;taxonomy;species group4|0|0Updated：2023-05-20
- Abstract：A new monstrilloid copepod species, Cymbasoma cheni sp. nov., from Meizhou Bay (an embayment in Fujian Province, southeastern China) is described and illustrated. The diagnostic character of the new species is the structure and armature of the fifth leg, which is represented by a single lobe armed with three naked setae subequal in length. The new species closely resembles Cymbasoma bowmani Suárez-Morales and Gasca, 1998 in the structure of the fifth legs, and the body proportions, including total body length, and relative lengths of the cephalothorax and the genital double somite. However, Cymbasoma cheni sp. nov. is distinguished by lack of cuticular ornamentation on the cephalothorax, the position of the oral papilla, and the structure of the fifth leg with three naked setae. Although the structure of the fifth legs is similar in Cymbasoma cheni sp. nov. and Cymbasoma quintanarooense (Suárez-Morales, 1994), the new species can be easily distinguished from Cymbasoma quintanarooense by the relative length of the antennule, differences in the genital double-somite and the ovigerous spines, and the shape of ocelli. This is the sixth record of this genus from China seas.Keywords：Copepoda;Monstrilloida;Cymbasoma;new species;Fujian Coast4|0|0Updated：2023-05-20
Biology
- Abstract：Sea cucumber Apostichopus japonicus is an important marine economic species in Asian countries due to its profound nutritional and medicinal value. So far, with the rapid development of intensified artificial aquaculture of sea cucumbers, the use of antibiotics is still an inexpensive and dispensable way to treat pathogenic infections, especially during the nursery phase. However, there is little information on the effects of antibiotics on the intestinal microbiota of sea cucumber. Therefore an Illumina based sequencing method was used to examine the intestinal bacterial composition of juvenile A. japonicas following diets with three typical antibiotics (tetracycline, erythromycin, and norfloxacin) under 15, 30, and 45 d. The findings reveal that different antibiotics have distinct effects on the growth performance of juvenile sea cucumbers. However, the richness and diversity of microbiota were barely affected by antibiotics but the community composition alterations indicated that the three antibiotics exhibited their respective patterns of reshaping the intestinal bacteria of juvenile sea cucumbers. In common, the abundance of some sensitive genera with helpful functions, such as Thalassotalea, Shewanella, Sulfitobacter, and Halomonas decreased significantly with exposure to antibiotics and the abundance of multiple potential pathogenic- and suspected antibiotic-resistant microorganisms like Arcobacter, Leucothrix, and Clostridium_sensu_stricto_1 was found increased significantly in the antibiotic groups. These results suggest that low doses of antibiotics could affect the composition of the intestinal microbiota of sea cucumbers and might increase the risk of infection of the hosts. This study could help us to explore how antibacterial compounds modify the gut microbiota of sea cucumbers and provide theoretical guidance in hatchery management by scientific antibiotic use in sea cucumber mariculture.Keywords：gut microbiota;sea cucumber;antibiotic;16S rRNA gene;illumina sequencing4|0|3Updated：2023-05-20
- Abstract：To identify the pathogen that causes scuticociliatosis in farmed-raised turbot Scophthalmus maximus, we isolated a ciliate from the brain tissue of an infected turbot and identified it as Uronema marinum based on morphological and molecular evidence. We then infected the turbots in artificial laboratory settings with pure cultured U. marinum. The infected turbots showed syndromes similar to those observed in naturally infected ones. Furthermore, microscopic examination and PCR detection confirmed the presence of the ciliate in the tissues of those laboratory-infected turbots. To our best knowledge, this is the first report of scuticociliatosis caused by U. marinum in farm-raised turbot S. maximus in China.Keywords：Scophthalmus maximus;scuticociliatosis;histopathology;Uronema marinum5|0|2Updated：2023-05-20
- Abstract：An abnormally high temperature produces a stress response in turbot causing large economic losses in the turbot aquaculture industry of China. A genetic improvement of the upper thermal tolerance (UTT) of turbot could allow cultured fish to adapt. A genetic evaluation of UTT is required for determining the practicability of including this trait into a breeding program. In this study, data were recorded from a temperature tolerance test conducted on 3 200 individual turbots from 32 full-sib groups. A cross-sectional linear model and a cross-sectional threshold probit model were used to analyze the test-period survival and a cross-sectional threshold logit model was used to analyze the test-day survival. In addition, phenotypic and genetic correlations between body weight and survival data were estimated. The estimated heritability values obtained from the cross-sectional linear model (CSL), the cross-sectional threshold (probit) model (THRp), and the cross-sectional threshold (logit) model (THRl) were 0.247 9±0.108 3, 0.288 3±0.161 2, and 0.106 9±0.045 2, respectively. The correlation coefficients among the full-sib family estimated breeding values (EBVs) obtained from the three models were greater than 0.998 6 and all models produced an almost identical family ranking. The accuracies of selection obtained with the CSL, THRp, and THRl model were 0.773 8, 0.775 4, and 0.784 4, respectively, the greatest from the THRl model. The genetic correlations between body weight and survival data EBVs from the CSL, THRp, and THRl models were 0.020 1, -6.201 1×10-4, and -3.115 4×10-4, respectively, and the phenotypic correlations between the two traits were -0.837 1 and -0.667 1, respectively. The findings of this study provide background information to determine the best strategy of selection for the genetic improvement of UTT in turbot.Keywords：Scophthalmus maximus;upper thermal tolerance;genetic parameters;cross-sectional models4|0|0Updated：2023-05-20
- Abstract：Understanding the feeding selectivity on phytoplankton by shellfish is currently a big challenge. In order to investigate the feeding behavior of bay scallop (Argopecten irradians) on phytoplankton, we compared its compositions of phytopigments in digestive glands with those in the surrounding seawater, and conducted five consecutive investigations between July and November 2016 in a bay scallop culture area along coast of Qinghuangdao City, northwest of the Bohai Sea, China. Phytopigments in four-size fractionated phytoplankton of seawater (micro-(20-200 μm); nano(L)-[10-20 μm]; nano(S)-[2.7-10 μm], and pico-[ < 2.7 μm]) and digestive glands of A. irradians were examined to investigate the selective feeding of A. irradians. Results show that fucoxanthin and peridinin constituted the major part of taxonomically diagnostic carotenoids (TDCs) in the micro-and nano(L)-phytoplankton in seawater. Compared with total phytoplankton biomass of seawater (TPB, sum of the four sizes), a substantial decrease of fucoxanthin proportion to total DCs in digestive glands was observed while that of peridinin, 19'-butanoyloxyfucoxanthin, alloxanthin and 19'-hexanoyloxy-fucoxanthin showed an obvious increase when those pigments were mainly confined to micro-sized phytoplankton (20-200 μm). However, zeaxanthin and prasinoxanthin were mainly confined to nano(s)-and pico-phytoplankton, of which the proportions in digestive glands were usually lower in TPB. The contribution of lutein to total DCs in digestive glands (with an average of 7.23%) increased compared with TPB of seawater (with an average of 0.63%) during all five sampling times.Keywords：phytoplankton;pigments;selective feeding;Argopecten irradians;aquaculture4|0|4Updated：2023-05-20
- Abstract：Pseudodiaptomus dubia is a calanoid copepod abundant in the mariculture ponds of southern China. However, our understanding of the population dynamics of P. dubia in aquaculture ponds is limited. In this study, groups of larval P. dubia were each fed a different microalgal species, and the effects of these different diets on development, survival, and reproduction were assessed. The five microalgae used were species common in aquaculture farms in China, and included two chlorophytes (Chlorella saccharophila and Platymonas subcordiformis), one golden microalga (Isochrysis zhanjiangensis), and two diatoms (Chaetoceros muelleri and Cyclotella meneghiniana). Our results indicated that C. saccharophila was not a suitable food for larval P. dubia, as all larvae fed this microalga died at stage Ⅲ (as copepodites). The survival rates of P. dubia larvae fed C. muelleri, I. zhanjiangensis, and P. subcordiformis were significantly higher than that of larvae fed C. meneghiniana. In the adult stage, copepods fed C. muelleri, I. zhanjiangensis, and C. meneghiniana produced more nauplii (430-566 nauplii/female), had higher intrinsic growth rates (0.2-0.253/d), and better longevity (59-60 days) than those fed P. subcordiformis. Our results therefore suggest that P. dubia has different nutritional needs and food preferences at different life stages. For example, P. subcordiformis was suitable for developing larvae but not for breeding adults, while C. meneghiniana was suitable for breeding adults but not for developing larvae. Both C. muelleri and I. zhanjiangensis were excellent foods for P. dubia throughout the entire life cycle.Keywords：copepods;development;reproduction;Pseudodiaptomus dubia;diet4|0|0Updated：2023-05-20
- Abstract：Biofloc technology has been applied successfully in the intensive aquaculture of several fish and shrimp species. The growth of heterotrophic microorganisms can be stimulated through adding extra carbon, which reduces the nitrogen level in the water and provides microbial protein to the animals. However, most of the studies and practical applications have been conducted in freshwater and marine environment. This paper focused on brine shrimp Artemia that lives in high salinity environment together with other halophilic or halotolerant microorganisms. The effect of carbon supplementation on Artemia growth, water quality, and microbial diversity of bioflocs was studied in the closed culture condition without any water exchange. The salinity of the culture medium was 100. A 24-d culture trial was conducted through supplementing sucrose at carbon/nitrogen (C/N) ratio of 5, 15, and 30 (Su5, Su15, and Su30), respectively. The culture without adding sucrose was used as a control. Artemia was fed formulated feed at a feeding ration of 60% recommended feeding level. The results showed that sucrose supplementation at higher C/N ratio (15 and 30) significantly improved the Artemia survival, growth and water quality (P < 0.05). Addition of sucrose at C/N ratio of 15 and 30 significantly increased biofloc volume (BFV) (P < 0.05). The Illumina MiSeq sequencing analysis showed that supplementing carbon at C/N ratio of 15 had a better total bacterial diversity and richness, and shaped the microbial composition at genera level. This study should provide information for studying the mechanism of biofloc technology and its application in high salinity culture conditions.Keywords：bioflocs;C/N ratio;Artemia growth;water quality;microbial diversity;high throughput sequencing4|0|2Updated：2023-05-20
- Abstract：To investigate the effects of salinity on early development of Chinese mitten crab (Eriocheir sinensis), and the salinity tolerance mechanism of embryos, different developmental stages of embryos (gastrula, eyespot and pre-hatching stage), and hatched stage Ⅰ zoea and megalopa, were exposed to a range of salinities (1, 5, 10, 15 (control), 20, 25, 30, 35 and 40). Hatching, survival and molting were monitored. Effects of 24-hour hypersaline (35) and hyposaline (1) stress on egg diameter, water content, Na+/K+-ATPase (NKA) activity, and crustacean hyperglycemic hormone (CHH) gene mRNA expression in embryos and megalopa, are reported. Embryos are more tolerant of low (≤5) than high (≥ 25) salinities, with optimum ranges for gastrula and pre-hatching stage embryos being 5-20, and for eyespot embryo and stage Ⅰ zoea, 10-20. Most megalopa can molt to the first juvenile instar by day 5 at salinities between 1 and 40, whereas molting of megalopa stages was delayed at 40. Hypersaline conditions resulted in a loss of moisture, reduction of egg volume, and a significant increase in NKA activity and CHH mRNA expression at some developmental stages. Hyposaline conditions did not affect moisture content or egg volume, but resulted in decreased NKA activity and CHH mRNA expression in embryos. For megalopa stages, NKA activity was significantly upregulated following both hypo-and hypersaline stress. Our results suggest high salinity will inhibit development and hatching of E. sinensis embryos, and low salinity will affect the survival of their stage Ⅰ zoea. Increased NKA activity in embryos and megalopa stages might indicate a hyporegulation response under hypersaline conditions. These findings provide useful information for spawning ground protection of indigenous E. sinensis and enrich the knowledge of embryonic tolerance mechanisms of hyperregulating crustaceans following osmotic stress.Keywords：Eriocheir sinensis;salinity;embryo development;zoea;megalopa;Na+/K+-ATPase4|0|2Updated：2023-05-20
Aquaculture and Fisheries
Corrigendum
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