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Volume 39 ， Issue 1 ， 2021
- Abstract：The HAMSOM (Hamburg Shelf Ocean Model), a high-resolution regional ice-ocean coupled model, was applied to investigate the seasonal evolution of Bohai Sea ice for winter 2015/2016. HAMSOM was initialized with monthly climatological temperature and salinity data from WOA13 and driven by hourly meteorological data obtained from the NCEP above the sea surface and tides at the open boundary. The ice model used here is a modified Hibler-type dynamic-thermodynamic sea ice model based upon viscous-plastic rheology. The ice extent, concentration, area, thickness, length of ice season as well as the distance between the top of Liaodong Bay (North China) and the outer ice edge line were simulated and compared with the observed data. Three types of modeling experiments were carried out to investigate the effects of wind, tide, and both wind and tide on Bohai Sea ice. The results show that wind, as both a dynamic and a thermodynamic factor, has a significant impact on the ice thickness, ice area, and ice-freezing and ice breakup dates as well as the ice velocity, while tides are a dynamic factor that influences only the ice velocity. During the severe ice period, the wind speed intensity increased by 25%, the average ice thickness thickened by approximately 4.0 cm in Liaodong Bay, approximately 2.1 cm in Bohai Bay and approximately 2.5 cm in Laizhou Bay, and the total ice coverage area and total ice actual area increased by about 2×104 km2 and 1.4×104 km2, respectively. While the tidal amplitude intensity increased by 25%, the average ice velocity increased by approximately 0.1 m/s.Keywords：Bohai Sea ice;ice-ocean coupled model;effects of wind and tides6|0|0Updated：2023-05-20
- Abstract：Upper ocean responses to the passage of sequential tropical cyclones over the northwestern South China Sea (SCS) in 2011 were investigated using satellite remote sensing data, Argo reanalysis data, and an array of mooring data. We found that the sea surface low temperature region lasted for more than 38 days and two phytoplankton blooms occurred after the passage of sequential tropical cyclones. The upper ocean cooling reached 2-5℃ with a right-side bias was observed along the typhoon track to about 200 km. The maintenance of low temperature region and the two phytoplankton blooms were mainly driven by upwelling and near-inertial turbulence mixing induced by the sequential tropical cyclones. The first phytoplankton bloom appeared on the 7th day after the passage of the three tropical cyclones, and the chlorophyll-a (chl-a) concentration increased by 226%, which may be mainly driven by typhoons induced upwelling. The second phytoplankton bloom occurred on the 30th day, the chl-a concentration increased by 290%. Further analysis suggested that only the typhoons with similar characteristics as Nesat and Nalgae can induce strong near-inertial oscillation (NIO). Strong turbulent mixing associated with the near-inertial baroclinic shear instability lasted for 26 days. The measured mean eddy diffusivity in the upper ocean was above 10-4 m2/s after typhoon Nesat. Enhancement of the turbulent mixing in the upper ocean helped to transport nutrient-rich cold waters from the deep layer to the euphotic layer, and is a major mechanism for the long-term maintenance of low temperature region as well as the second phytoplankton bloom.Keywords：sequential tropical cyclones;two phytoplankton blooms;tropical cyclones induced upwelling;turbulence mixing by the near-inertial baroclinic shear instability4|0|0Updated：2023-05-20
- Abstract：Features of the interannual variability of the spring Wyrtki Jet in the tropical Indian Ocean are revealed using observation data and model output. The results show that the jet has significant interannual variation, which has a significant correlation with winter El Niño Modoki index (R=0.62). During spring after an El Niño (La Niña) Modoki event, the Wyrtki Jet has a positive (negative) anomaly, forced by a westerly (easterly) wind anomaly. The result of a linear-continuously stratified model shows that the first two baroclinic modes explain most of the interannual variability of the spring Wyrtki Jet (~70%) and the third to fifth modes together account for approximately 30%. Surface wind anomalies in the tropical Indian Ocean are related to the Walker circulation anomaly associated with El Niño/La Niña Modoki. The interannual variability of the spring Wyrtki Jet has an evident impact on sea surface salinity transport before the onset phase of the summer monsoon in the Indian Ocean.Keywords：Equatorial Indian Ocean;Wyrtki Jet;interannual variability;El Niño/La Niña Modoki5|1|4Updated：2023-05-20
- Abstract：This study is the first to depict typhoon-induced continental shelf wave (CSW) propagation in the eastern Taiwan Strait (TWS) during the passage of Typhoon Meranti in 2016 using tidal gauge data and along-track satellite altimeter data. The strong amplitude response of sea level oscillations (within the range of 0.30-0.54 m) as a free, barotropic CSW after Meranti, which impacted the TWS, was clearly detected in time and frequency (in bands of 64-81 h) using wavelet and cross-wavelet analyses. The measured group and phase speeds were consistent with the dispersion curves for CSW with the first-mode derived from the cross-shelf sections of the eastern TWS, with the mean speeds reaching 3 and 5.6±0.7 m/s, respectively. Coincidentally, the typhoon-induced sea level anomaly (SLA) was also captured by the satellite altimeter before this CSW entered into the TWS. Using the theoretical cross-shore CSW modes to fit the SLA data, the results indicated that the first three wave modes can interpret this CSW event appeared in the southern TWS very well, with the first mode being the dominant one.Keywords：continental shelf wave (CSW);tidal gauge data;satellite altimeter data;typhoon;Taiwan Strait4|0|2Updated：2023-05-20
- Abstract：Near-diurnal vertically-standing waves with high vertical wavenumbers kz were observed in the velocity and shear fields from a set of 75-d long ADCP moored in the northeastern South China Sea (SCS) away from the "critical" latitude of 28.8°. These enhanced near-diurnal internal waves followed a fortnightly spring-neap cycle. However, they always happened during semidiurnal spring tides rather than diurnal springs although strong diurnal internal tides with the fortnightly spring-neap cycle were prevailing, suggesting that they were generated via subharmonic instability (PSI) of dominant semidiurnal M2 internal tides. When two semidiurnal internal tidal waves with opposite vertical propagation direction intersected, both semidiurnal subharmonic and super harmonic waves were largely intensified. The observed maximum diurnal velocity amplitudes were up to 0.25 m/s. The kinetic energy and shear spectra further suggested that frequencies of daughter waves were not always perfectly equal to M2/2. The superposition of two daughter waves with nearly equal frequencies and nearly opposite kz in a PSI-triad leaded to the vertically-standing waves.Keywords：internal tides;South China Sea (SCS);resonant interactions;rotary spectra;parametric subharmonic instability4|0|2Updated：2023-05-20
- Abstract：The vertical mixing parameterization scheme, by providing the effects of some explicitly missed physical processes and more importantly closing the energy budgets, is a critical model component and therefore imposes significant impacts on model performance. The Yellow Sea Cold Water Mass (YSCWM), as the most striking and unique phenomenon in the Yellow Sea during summer, is dramatically affected by vertical mixing process during its each stage and therefore seriously sensitive to the proper choice of parameterization scheme. In this paper, a hindcast of YSCWM in winter of 2006 was implemented by using the Regional Ocean Modeling System (ROMS). Three popular parameterization schemes, including the level 2.5 Mellor-Yamada closure (M-Y 2.5), Generic Length Scale closure (GLS) and K-Profile Parameterization (KPP), were tested and compared with each other by conducting a series of sensitivity model experiments. The influence of different parameterization schemes on modeling the YSCWM was then carefully examined and assessed based on these model experiments. Although reasonable thermal structure and its seasonal variation were well reproduced by all schemes, considerable differences could still be found among all experiments. A warmer and spatially smaller simulation of YSCWM, with very strong thermocline, appeared in M-Y 2.5 experiment, while a spatially larger YSCWM with shallow mixed layer was found in GLS and KPP schemes. Among all the experiments, the discrepancy, indicated by core temperature, appeared since spring, and grew gradually by the end of November. Additional experiments also confirmed that the increase of background diffusivity could effectively weaken the YSCWM, in either strength or coverage. Surface wave, another contributor in upper layer, was found responsible for the shrinkage of YSCWM coverage. The treatment of wave effect as an additional turbulence production term in prognostic equation was shown to be more superior to the strategy of directly increasing diffusivity for a coastal region.Keywords：Yellow Sea Cold Water Mass (YSCWM);vertical mixing parameterizations;thermocline;background diffusivity;surface wave induced mixing5|0|1Updated：2023-05-20
Physics
- Abstract：The content and distribution pattern of rare earth elements (REEs) in surface sediments from the Eastern and Western Pacific Ocean, the Northern and Southern Atlantic Ocean, and the Southwestern Indian Ocean were explored and the resources and geochemical characteristics of REEs in deep-ocean sediments from different oceans were studied. The total REE abundances (∑REE) in the different oceans ranged as follows:Eastern Pacific, 56.88-500.02 μg/g; Western Pacific, 290.68-439.94 μg/g; Northern Atlantic, 55.33-154.90 μg/g; Southern Atlantic, 40.83-69.30 μg/g; and Southwestern Indian Ocean, 20.24-64.76 μg/g. Their corresponding LREE (La-Eu)/HREE (Gd-Lu) average values were 5.18, 5.86, 9.01, 5.21, and 4.59, which indicated that the light REEs were all evidently enriched. δEu and δCe showed slight Eu-negative anomalies and significant Ce-positive anomalies in all sediments. Although the contents of REEs in the sediments varied among the different oceans, the distribution patterns of REEs were similar, and the correlation coefficient was greater than 0.929 0. In the Eastern Pacific sediments, ΣREE showed a significantly positive correlation with Co, Cu, Zn, Mn, Mo and a weak correlation with Fe. In the Western Pacific and Southern Atlantic sediments, ΣREE presented no obvious correlation and a weakly negative correlation with Co, Cu, Zn, Mn, Mo and Fe, respectively. ΣREE in the Southwestern Indian Ocean sediments positively correlated with Cu, Zn, Mn, Mo, Fe, and had a weakly negative correlation with Co.Keywords：rare earth elements (REE) geochemistry;distribution pattern;REE fractionation;marine sediment4|0|1Updated：2023-05-20
- Abstract：To understand the petrogenesis and magma evolution history in the Eastern Manus Basin (EMB), geochemistry of pyroxene and plagioclase mineral phenocrysts in basaltic andesites and dacites were reported. The plagioclase-melt thermometry showed that, plagioclase in dacites crystalized in 1 027.2-1 028.5℃ under 3.37-5.08 kbar, whereas in basaltic andesite was 1 181.4-1 187.0℃ under 1.79-4.46 kbar. Pyroxene compositions and invariable La/Sm vs La values of whole rock powders indicate that lavas were erupted in rapid cooling rate and mainly controlled by fractional crystallization (FC). In addition, oscillatory zonings in plagioclase and pyroxene phenocrysts indicated small local perturbations and degassing episodes in the magma chamber. Some high Mg# clinopyroxene antecrysts were found in EMB lavas. The highest Mg# of parental EMB melts is 69, which falls into the range of initial partial melts from upper mantle peridotite source (68-75). In terms of isotopic compositions, the EMB lavas most likely originated from Indian-type MORB mantle which was influenced by subduction components. In details, the subduction components are mainly derived from the dehydration of a subducted altered oceanic crust, and the contribution of sediment influence is minor. The Pb isotopic compositions and end member modeling further suggest that the source of subduction components is more likely from the Pacific Plate instead of the Solomon Plate.Keywords：Eastern Manus Basin;plagioclase;pyroxene;whole rock;Sr-Nd-Pb isotope;magma4|0|0Updated：2023-05-20
Geology
- Abstract：Marine biogenic emission of dimethylsulfide (DMS) has been well recognized as the main natural source of reduced sulfur to the remote marine atmosphere and has the potential to affect climate, especially in the polar regions. We used a global climate model (GCM) to investigate the impact on atmospheric chemistry from a change to the contemporary DMS flux to that which has been projected for the late 21st century. The perturbed simulation corresponded to conditions that pertained to a tripling of equivalent CO2, which was estimated to occur by year 2090 based on current worst-case greenhouse gas emission scenarios. The changes in zonal mean DMS flux were applied to 50°S-70°S Antarctic (ANT) and 65°N-80°N Arctic (ARC) regions. The results indicate that there are clearly different impacts after perturbation in the southern and northern polar regions. Most quantities related to the sulfur cycle show a higher increase in ANT. However, most sulfur compounds have higher peaks in ARC. The perturbation in DMS flux leads to an increase of atmospheric DMS of about 45% in ANT and 33.6% in ARC. The sulfur dioxide (SO2) vertical integral increases around 43% in ANT and 7.5% in ARC. Sulfate (SO4) vertical integral increases by 17% in ANT and increases around 6% in ARC. Sulfur emissions increases by 21% in ANT and increases by 9.7% in ARC. However, oxidation of DMS by OH increases by 38.2% in ARC and by 15.17% in ANT. Aerosol optical depth (AOD) increases by 4% in the ARC and by 17.5% in the ANT, and increases by 22.8% in austral summer. The importance of the perturbation of the biogenic source to future aerosol burden in polar regions leads to a cooling in surface temperature of 1 K in the ANT and 0.8 K in the ARC. Generally, polar regions in the Antarctic Ocean will have a higher offsetting effect on warming after DMS flux perturbation.Keywords：dimethylsulfide (DMS);sulfur dioxide;DMS sea-to-air flux;perturbation;global climate model (GCM);polar region4|0|3Updated：2023-05-20
- Abstract：Antibiotics released into the environment through anthropogenic activities exert selective pressure, driving bacteria towards increasing antimicrobial resistance. The prevalence of antibiotics and the ecological risks posed in the riverine estuarine of Larut River and Sangga Besar River, which included wastewater effluents from hospital, zoo, and poultry slaughterhouse sources were investigated. Solid phase extraction (SPE) followed by high-performance liquid chromatography tandem mass chromatography (HPLC-MS/MS) were used to extract and quantify the antibiotic residues from 22 antibiotics belonging to six major antibiotic classes (sulfonamide, macrolide, fluoroquinolone, phenicol, trimethoprim, and tetracycline). Sixteen antibiotic residues were detected with concentrations ranging from limit of detection (LOD) to 1 262.3 ng/L. Fluoroquinolones and macrolides were the most frequently detected compounds. Erythromycin, clarithromycin, and ofloxacin detected in hospital and zoo effluents posed a high risk to algae while tetracycline had low to medium ecological risks toward all the relevant organisms from aquatic environments (algae, invertebrate Daphnia magna, and fish).Keywords：antibiotic residues;prevalence;ecological risk;anthropogenic pollution;riverine;estuarine4|0|0Updated：2023-05-20
Chemistry
- Abstract：Coral restoration is becoming popular to help restoring degraded coral reefs. However, few studies have tried to monitor the long-term recovery of coral reefs, which makes it difficult to assess the performance of the restoration. We monitored the growth of three transplanted Acropora corals and naturally-attached Pocillopora damicornis on artificial reefs (ARs) from October 2014 to September 2018 during which there were several attacks of typhoons. Results show that two staghorn Acropora species had the highest growth rates (11.0-12.1 cm/a), followed by table coral A. divaricate (5.6 cm/a) and P. damicornis (4.8 cm/a). A linear growth pattern was found for the three Acropora species; the pattern gradually slowed in P. damicornis. There was a strong interspecific competition for space among the corals on ARs, and it led to the sharply declined occurrence of slow-growing P. darmicornis colonies in 2017. Coral recovery was successful at the Wuzhizhou Island and quickly increased AR complexity. However, the ARs made of metal frames fail to resist the direct attack from a catastrophic typhoon. Therefore, concrete and environmentalfriendly materials should be used in future restoration. This study is the first report on long-term monitoring and assessment of coral reef restoration in China. The results offer future guide of reef restoration for impaired coral reefs in regions easily affected by typhoons.Keywords：coral restoration;artificial reefs;coral transplantation;Acropora;Pocillopora damicornis4|0|5Updated：2023-05-20
- Abstract：In tropical waters where temperatures are relatively stable, we investigated whether the relationship between phytoplankton growth and grazing loss rate across different habitats around Peninsular Malaysia can be attributed to its eutrophication states. We measured phytoplankton growth (μ) and grazing loss (g) rates in waters off Bachok Marine Research Station (BMRS), located northeast of Peninsular Malaysia. Chlorophyll-a (chl-a) concentration ranged from 2.90 to 15.78 μg/Land was dominated by nanoand micro-phytoplankton (>2 μm in size). Using the Landry and Hassett dilution method, μ at BMRS ranged from 1.02 to 1.58/d whereas g varied from 0.07 to 0.88/d. Grazing accounted for 35% of the primary production at BMRS. A systematic review of available data in waters around Peninsular Malaysia, revealed how μ fluctuated over a wide range (0.01-1.80/d) and correlated with chl a distribution (R2=0.181, P < 0.001). However, the relationship was only significant at < 9 μg/L chl a for mesotrophic waters and < 16 μg/L chl a for eutrophic waters. In contrast, g ranged from 0.00 to 1.01/d, and correlated with μ at all locations. The g/μ slope ranged from 19% to 84%, and was generally similar for waters around Peninsular Malaysia. However, all the g/μ slopes had a positive y-intercept except for BMRS, and this seemed to suggest the availability of alternative prey supporting grazing at the other stations.Keywords：phytoplankton growth;grazing loss;grazing pressure;Bachok Marine Research Station (BMRS)4|1|0Updated：2023-05-20
- Abstract：The increasing use of pharmaceuticals has become a major environmental issue in China. The presence of antibiotics in water may have deleterious effects on non-target aquatic organisms such as microalgae. In this study, a cyanobacterium and an alga species in surface waters, Microcystis aeruginosa and Chlamydomonas microsphaera, were exposed to 0, 0.1, 0.5, 1.0, 2.0, 5.0, 10.0, and 20.0 mg/L of oxytetracycline dihydrate (OXY) and sulfamethoxazole (SMZ) for 96 h to determine the effects of these antibiotics on the growth and surface morphology. Moreover, the photosynthetic activity and the contents of superoxide dismutase (SOD), malondialdehyde (MDA), and protein were measured to examine the biochemical characteristics of M. aeruginosa and C. microsphaera under OXY and SMZ stress. The effects of both antibiotics on the growth of both species were concentration-dependent and characterized by low-dose stimulation and high-dose inhibition. C. microsphaera was more sensitive to both antibiotics than M. aeruginosa was. The algal cell membranes of both species disintegrated after exposure to a high concentration of OXY. All of the physiological parameters measured in this study were relatively stable at low concentrations of OXY and SMZ. After exposure to high concentrations of OXY and SMZ, photosynthetic activity decreased significantly, whereas lipid peroxidation and the abundance of SOD, MDA, and protein increased significantly. Thus, low-dose antibiotics may increase algal blooms in eutrophic waters.Keywords：antibiotics;cyanobacterium;green algae;physiology;growth4|0|1Updated：2023-05-20
- Abstract：Ophiopholis mirabilis is a common species with a high population density on the western coasts of the northern Pacific Ocean. The number of O. mirabilis has been increasing recently in the scallop aquaculture zone (the Zhangzi Island area, northern Yellow Sea) in China. To explore the mechanism of its population variation, the reproductive cycle of O. mirabilis was investigated in this area (39°04'N; 122°51'E) from February 2017 through January 2018 and determined by the monthly gonad index (GI), histological examinations of the gonads and the oocyte size-frequency distribution. O. mirabilis had a clear annual reproductive cycle that was synchronous between males and females. Sea temperature and food availability played important roles in O. mirabilis reproduction. The GI value was less reliable for determining reproductive activity in O. mirabilis because the nutritive tissues within the gonads may be utilized to synthesize gametes, leading to a decrease in GI during maturation. The histological results also show that abundant nutritive phagocytes were present in the gonads of O. mirabilis, which, together with the germ cells, affected the weight of the gonads. In addition, the mature oocytes of O. mirabilis were relatively small (75-150 μm), indicating that the larval development was planktotrophic. This study provided insights into the reproductive patterns and biology of O. mirabilis and is an essential basis for the quantity control of this species in aquaculture areas.Keywords：reproductive biology;Ophiuroidea;the northern Pacific Ocean;Ophiopholis mirabilis4|0|0Updated：2023-05-20
- Abstract：Sulfate-reducing bacteria (SRB) are ubiquitous anaerobic microorganisms that play significant roles in the global biogeochemical cycle. Coastal wetlands, one of the major habitats of SRB, exhibit high sulfate-reducing activity and thus play significant roles in organic carbon remineralization, benthic geochemical action, and plant-microbe interactions. Recent studies have provided credible evidence that the functional rather than the taxonomic composition of microbes responds more closely to environmental factors. Therefore, in this study, functional gene prediction based on PacBio single molecular real-time sequencing of 16S rDNA was applied to determine the sulfate-reducing and organic substrate-decomposing activities of SRB in the rhizospheres of two typical coastal wetland plants in North and South China:Zostera japonica and Scirpus mariqueter. To this end, some physicochemical characteristics of the sediments as well as the phylogenetic structure, community composition, diversity, and proportions of several functional genes of the SRB in the two plant rhizospheres were analyzed. The Z. japonica meadow had a higher dissimilatory sulfate reduction capability than the S. mariqueter-comprising saltmarsh, owing to its larger proportion of SRB in the microbial community, larger proportions of functional genes involved in dissimilatory sulfate reduction, and the stronger ability of the SRB to degrade organic substrates completely. This study confirmed the feasibility of applying microbial community function prediction in research on the metabolic features of SRB, which will be helpful for gaining new knowledge of the biogeochemical and ecological roles of these bacteria in coastal wetlands.Keywords：sulfate-reducing bacteria (SRB);microbial community function prediction;16S rDNA PacBio SMRT sequencing;Zostera japonica;Scirpus mariqueter;rhizosphere4|0|1Updated：2023-05-20
- Abstract：The exposed calcareous rocky area of the Abu Qir Headland, east of Alexandria, Egypt which range from coarse grains, through pebbles, cobbles, and boulders to rocky platforms, was significantly colonized by sclerobionts (epibionts and endobionts). The epibiont species diversity was comparatively higher than that of endobionts. Epibiont communities included bryozoans (the anascan-grade cheilostome Biflustra savartii), serpulid (Hydroides elegans, Spirobranchus cf. tetraceros, Vermiliopsis striaticeps and Protula or Apomatus) and spirorbid (Spirorbis) wormtubes, and balanoid barnacles (Amphibalanus amphitrite, Balanus trigonus, and Perforatus perforatus). The cheilostome bryozoan colonies, which developed extensive sheets, proliferated on the study rocky shore either encrusting the bioeroded basement directly, or encrusting other epilithic taxa, particularly balanoid barnacles and serpulid worms. Encrusters displayed a remarkable marginal competitive interaction (overgrowth and stand-off) for space on the study rocky shore. On the other hand, endobionts were not well represented on the studied rocky shore exposure. It was possible to identify three ichnotaxa:Gastrochaenolites, Maeandropolydora, and Finichnus. The findings documented represent a significant contribution to our knowledge of sclerobionts composition, sequence of their colonization and/or bioerosion, and their mutual relationships on the intertidal rocky shore of the Abu Qir Headland.Keywords：sclerobionts;encrustation;bioerosion;Mediterranean;Egypt4|0|0Updated：2023-05-20
- Abstract：The Yellow Sea Cold Water Mass (YSCWM) is a distinct hydrographic phenomenon of the Yellow Sea, and the distribution pattern of meio- and macrobenthos differs inside and outside of the YSCWM. However, such a pattern has never been observed in the microbenthic ciliate communities. Therefore, we hypothesized that benthic ciliates followed a similar distribution pattern as meio- and macrobenthos, but this pattern has not been uncovered by morphological methods. We evaluated the diversity and distribution of benthic ciliates at five stations along hydrographic gradients across the YSCWM and adjacent shallow water by using morphology and DNA and complementary DNA (cDNA) high-throughput sequencing of the V4 region of 18S rRNA gene. Results showed that the diversity of benthic ciliates detected by DNA (303 OTUs), and the cDNA (611 OTUs) sequencing was much higher than that detected by the morphological method (79 species). Morphological method detected roughly different ciliate communities inside and outside of the YSCWM, but without statistical significance. No clear pattern was obtained by DNA sequencing. In contrast, cDNA sequencing revealed a distinct distribution pattern of benthic ciliate communities like meioand macrobenthos, which coincided well with the results of the environmental parameter analysis. More than half of the total sequences detected by DNA sequencing belonged to planktonic ciliates, most (if not all) of which were recovered from historic DNA originating through the sedimentation of pelagic forms because none of them were observed morphologically. The irrelevant historic DNA greatly influenced the recovery of rare species and thus limited the understanding of the benthic ciliate diversity and distribution. Our research indicates that the methods used have significant effects on the investigation of benthic ciliate communities and highlights that cDNA sequencing has great advantages in estimating the diversity and distribution of benthic ciliates, as well as the potential for benthic environmental assessments.Keywords：benthic ciliates;cDNA high-throughput sequencing;community comparison;DNA highthroughput sequencing;morphology5|0|4Updated：2023-05-20
- Abstract：A mass-balanced Ecopath model presents a quantitative description of the trophic structure, flow of energy and trophic interaction among ecological groups of an ecosystem. The Ecopath with Ecosim (EwE) modeling program (Version 6.5) was used to develop a preliminary trophic model for a tropical freshwater reservoir. The total fish biomass was 6.245 t/km2 and the highest trophic level of the reservoir was 3.362 (for snakehead). The ecosystem is phytoplankton based because primary producers originated 68% and detritus originated 32% of the total flow from lower trophic level. The gross efficiency of the fishery was 0.004, suggesting the inefficiency of the system. The positive effect of phytoplankton and detritus on most of the other groups were evident from mixed trophic analysis while moderately higher ecotrophic efficiency (EE) of phytoplankton shows the ecosystem's potential bottom-up control. The competition for the same resources among different groups was also obvious. The ratio of primary production/respiration (1.969) suggests that the ecosystem is at the developing stage and utmost contemplation should be given to concerned human activities. The low value of relative ascendancy (30.13) and overhead (69.87) reveals the stability of the ecosystem and some degrees of maturity. It also predicts the presence of significant strength in reserve of the system to withstand or overcome any perturbation. However, ecologically sustainable resource management plans should be implemented to ensure the sustainability of this reservoir resources.Keywords：Ecopath;Kaptai reservoir;trophic interaction;transfer efficiency;energy flow4|0|1Updated：2023-05-20
Ecology
- Abstract：On May 24-29,2019,a harmful algal bloom occurred in Pingtan coastal areas,Fujian,southeast China,and caused mass mortality of cage-cultured fish. Two clonal cultures of an unknown naked dinoflagellate were set up from seawater samples taken during the bloom. The cultures were examined for morphological features,ultrastructure characters,photosynthetic pigments,the large subunit (LSU) of the rRNA gene,and the internal transcribed spacer (ITS) sequences,as well as acute toxicity analysis. The cell was unarmored,small-sized,and ovoid,and was characterized by elaborate striations on the epicone and hypocone. The nucleus was large,ellipsoid to oval or kidney-shaped,and centrally located in the cell. A long linear apical groove originated above the sulcus in the ventral epicone and extended to the dorsal side. An elongate,slit-like "ventral pore" was located on the left of the epicone,well away from the apical groove. The chloroplasts were yellowish brown,numerous,band like,and irregularly distributed in the cell periphery. Fucoxanthin was the main accessory pigment composition. Phylogeny topology reconstructed on partial LSU rDNA showed that the unknown dinoflagellate branched as a sister species to Karlodinium sp. (strain IFR981 & IFR797,from France) and Karlodinium corrugatum (strain KDGSO08,from Australia),with genetic divergences of 0.6% and 3.3%,respectively. Based on the morphological and molecular phylogenetic analysis,we describe the novel dinoflagellate as Karlodinium elegans sp. nov. A toxicity assay revealed that the clonal culture of K. elegans (strain PTB601) had no adverse effect on brine shrimp (Artemia salina) and marine medaka (Oryzias melastigma),indicating it may not be a toxic species.Keywords：Karlodinium;Kareniaceae;harmful algal bloom;toxicity;dinoflagellate4|0|0Updated：2023-05-20
- Abstract：Ulva linza is one of the species that causes green tides in the Yellow Sea,China. Due to the difficulties in chromosomal preparation,the large numbers of chromosomes,and their relatively small sizes,there have been no reported studies on Ulva macroalgae chromosomes. The karyotypes and chromosomes in U. linza were observed after a series of treatments. The chromosomes were pretreated with 0.1% colchicine for 12 h and then mixed with enzymes. The samples were dropped from 30 cm height onto glass slides,which spread out the surface coat. These pretreatments were the optimal chromosomes preparation treatments. The prepared chromosomes were stained with 4',6-diamidino-2-phenylindole (DAPI),which is a fluorescent probe sensitive and specific to DNA. The chromosome number in the haploid male and female gametophytes was n=9,and was 2n=18 in the diploid sporophytes. The female gametophyte chromosomes were between 0.804 and 2.292 μm in size,the male gametophyte chromosomes were between 0.917 and 2.916 μm,and the sporophyte chromosomes were between 0.912 and 2.167 μm. The relative sizes of the chromosomes were used to analyze the karyotypes of the female and male gametophyte chromosomes. The results provide a solid foundation for the basic technique that can be used to localize molecular markers of Ulva chromosomes.Keywords：Ulva linza;gametophytes;sporophytes;chromosome;karyotype4|0|0Updated：2023-05-20
- Abstract：The Mariana Trench, the deepest trench on the earth, is ideal for deep-sea adaptation research due to its unique characters, such as the highest hydrostatic pressure on the Earth, constant ice-cold temperature, and eternal darkness. In this study, tissues of a the hadal holothurian (Paelopatides sp.) were fixed with RNA later in situ at ~6 501-m depth in the Mariana Trench, which, to our knowledge, is the deepest in-situ fixed animal sample. A high-quality transcript was obtained by de-novo transcriptome assembly. A maximum likelihood tree was constructed based on the single copy orthologs across nine species with their available omics data. To investigate deep-sea adaptation, 113 positively selected genes (PSGs) were identified in Paelopatides sp. Some PSGs such as microphthalmia-associated transcription factor (MITF) may contribute to the distinct phenotype of Paelopatides sp., including its translucent white body and degenerated ossicles. At least eight PSGs (transcription factor 7-like 2[TCF7L2], ETS-related transcription factor Elf-2-like [ELF2], PERQ amino acid-rich with GYF domain-containing protein[GIGYF], cytochrome c oxidase subunit 7a, [COX7A], type I thyroxine 5'-deiodinase[DIO1], translation factor GUF1[GUF1], SWI/SNF related-matrix-associated actin-dependent regulator of chromatin subfamily C and subfamily E, member 1[SMARCC] and[SMARCE1]) might be related to cold adaptation. In addition, at least nine PSGs (cell cycle checkpoint control protein[RAD9A], replication factor A3[RPA3], DNA-directed RNA polymerases I/Ⅱ/Ⅲ subunit RPABC1[POLR2E], putative TAR DNA-binding protein 43 isoform X2[TARDBP], ribonucleoside-diphosphate reductase subunit M1[RRM1], putative serine/threonine-protein kinase [SMG1], transcriptional regulator[ATRX], alkylated DNA repair protein alkB homolog 6[ALKBH6], and PLAC8 motif-containing protein[PLAC8]) may facilitate the repair of DNA damage induced by the high hydrostatic pressure, coldness, and high concentration of cadmium in the upper Mariana Trench.Keywords：sea cucumber;Mariana Trench;deep-sea adaptation;positive selection analysis;translucent white body;ossicle degeneration4|0|0Updated：2023-05-20
- Abstract：Coloration is an important phenotypic trait for multiple adaptive functions. It is interesting to find white-eye (AW) and orange-eye (AO) phenotypes in the shrimp Alvinocaris longirostris inhabiting the deep-sea cold seep and hydrothermal vent areas of the northwestern Pacific. By comparative transcriptome analyses,1 491 differentially expressed genes (DEGs) were identified between AW and AO. Among them,many DEGs were associated with immunity,antioxidation,and detoxification. Two significant enzyme encoding genes,xanthine dehydrogenase,and tryptophan oxidase involved in pigment biosynthesis pathways were up-regulated in AW and AO,respectively,which might be related to the differences of white and orange eye phenotypes. Moreover,single nucleotide polymorphism (SNP) calling detected that genotypes of 28 SNP distributing in 14 unigenes were completely different between AW and AO. Particularly,there were three and two non-synonymous mutations in immune genes crustin Pm5 and antimicrobial peptide,respectively. Results indicate that the difference in eye color is probably resulted from immune response to variable micro-environmental stressors encountered in the dispersal process of the shrimps,such as symbiotic microbes,pathogens,and toxic substances,and might be genetically fixed at last. The suggested pathway preliminarily explained the formation mechanism of different eye phenotypes in Alvinocaridid shrimps,providing a basis for further study on adaptive evolution of eyes in deep-sea chemosynthetic faunas.Keywords：alvinocaridid shrimps;cold seep and hydrothermal vent;differentially expressed genes;eye color;single nucleotide polymorphism (SNP) mutation;transcriptome4|0|0Updated：2023-05-20
- Abstract：Resazurin (RZ) is a weakly fluorescent blue dye and can be reduced irreversibly to highly fluorescent pink resorufin (RF) that is reduced reversibly to colorless dihydroresorufin (hRF) by photodeoxygenation, chemical reaction and reductive organic compounds produced through cell metabolism. Because of the reliable and sensitive fluorescence-color change and noninvasive features, RZ has been used widely as a redox indicator in cell viability/proliferation assays for bacteria, yeast, and mammalian cells. However, RZ is used rarely for physiological characterization of marine microorganisms. Here, we developed a custom-made irradiation and absorption-analysis device to assess the reducing capacity and physiologic status of marine bacterial cultures. We measured the absorption spectra of RZ, RF, and hRF in the presence of the reducing compound Na2S and under visible-light irradiation. After establishing appropriate parameters, we monitored the color changes of RZ and its reduced derivatives to evaluate the coherence between reducing capacity, bioluminescence and growth of the deep-sea bacterium Photobacterium phosphoreum strain ANT-2200 under various conditions. Emission of bioluminescence is an oxidation process dependent upon cellular reducing capacity. Growth and bioluminescence of ANT-2200 cell cultures were impeded progressively with increasing concentrations of RZ, which suggested competition for reducing molecules between RZ at high concentration with reductive metabolism. Therefore, caution should be applied upon direct addition of RZ to growth media to monitor redox reactions in cell cultures. Analyses of the instantaneous reduction velocity of RZ in ANT-2200 cell cultures showed a detrimental effect of high hydrostatic pressure and high coherence between the reducing capacity and bioluminescence of cultures. These data clearly demonstrate the potential of using RZ to characterize the microbial metabolism and physiology of marine bacteria.Keywords：oxic-reduction indicator;absorption spectra;bacterial growth;marine microorganism4|0|0Updated：2023-05-20
- Abstract：The wingless-related integration site (WNT) proteins are a family of secreted glycoproteins that are evolutionarily conserved and are believed to be involved in evolution in vertebrates and invertebrates. WNT signaling pathways may be associated with limb regeneration and development in crustaceans. However, the detail mechanisms remain unclear. Therefore, the distribution of WNT4 in the hepatopancreas, muscle, hemocyte, ganglion, heart, eyestalk, gill tissue, and different larvae development stages of the swimming crab (Portunus trituberculatus) were characterized using immunofluorescence, real-time PCR, and Western blotting. Significant PtWNT4 expression was detected in heart and eyestalk. In addition, PtWNT4 was expressed in all larval stages of P. trituberculatus with a dynamic expression pattern, especially in the eyestalk and other organs in the carapace area. The injection of WNT4 dsRNA into regenerative limbs significantly decreased PtWNT4 mRNA levels in the eyestalk, heart, and muscle, resulting in 1.9-fold, 2.2-fold, and 2.7-fold decreases compared with those detected in the group injected with crab saline (P < 0.05), respectively, indicating successful gene silencing. Overall, expression analysis on the WNT4 using RNAi provides an insight to its functional mechanism during limb regeneration in P. trituberculatus. The results not only demonstrated the requirement for WNT4 in limb regeneration of Crustaceans, but also suggested its ability to promote larval development at specific stages.Keywords：wingless-type MMTV integration site family member-4(WNT4);limb regeneration;larvae development;Portunus trituberculatus;expression pattern;RNAi4|0|1Updated：2023-05-20
Biology
- Abstract：The unfolded protein response (UPR) is an important protective and compensatory strategy used during endoplasmic reticulum stress caused by factors including glucose starvation, low pH, or heat shock. However, there is very little information on the possible role(s) of the UPR under adverse conditions experienced by marine invertebrates. We observed that rough endoplasmic reticulum (ER) was dramatically expanded and numerous autophagosomes were accumulated in the intestinal cells of sea cucumbers, Apostichopus japonicus, under heat stress (4 h at 25℃ compared with 15℃ controls). Moreover, heat stress led to sharp increases in the relative transcript and protein expression levels of two primary ER chaperones:the endoplasmic reticulum resident protein 29-like (ERP29) and protein disulfide-isomerase A6-like (PDIA6). These results suggest a potential adaptive mechanism to deal with heat-induced stress in sea cucumber intestine.Keywords：Apostichopus japonicus;endoplasmic reticulum (ER);unfolded protein response (UPR);endoplasmic reticulum resident protein 29-like (ERP29);protein disulfide-isomerase A6-like (PDIA6)4|0|0Updated：2023-05-20
- Abstract：Disease in clams frequently occurred over the last decade and has become a serious threat to the clam aquaculture industry and natural stocks. Mass clam mortality events were reported to be associated with the presence of opportunistic pathogen vibrio. However, the complexity of infection that occurs in the natural environment remains poorly understood. In this study, we smulated a natural disease outbreak by vibrio immersion infection to study the diversity and dynamics of microbiota in the digestive tract of clam Meretrix petechialis during the infection process. Dramatic changes in operational taxonomic unit richness and phylum composition of the bacterial communities were observed during pathogen invasion. In addition, we investigated the potential relationship between microbiota dynamics and host status during disease progression. Results reveal that, at the end stage of vibrio infection, interindividual variation in the digestive tract microbiota increased, as did the difference in individual health status. The moribund clams displayed signs of microbial community shifts to low diversity, and the microbial community was characterized by mass proliferation of a few operational taxonomic units.Keywords：Meretrix petechialis;vibrio challenge;16S ribosomal RNA;bacterial community;digestive tract4|0|2Updated：2023-05-20
- Abstract：A variety of shell colors are one of the most fundamental characteristics of molluscs, which have importantly ecological and economic significance. The Pacific oyster Crassostrea gigas is distributed in many sea areas around the world and also an aquacultured mollusc with high nutritional value. In this study, the whole soft body and the mantle tissue of black-shelled Pacific oyster (BSO) and white-shelled Pacific oyster (WSO) with starkly different melanin contents were compared, and the differences in physiology and metabolism between BSO and WSO were analyzed. The results of physiological indicators suggested BSO show more melanin, more dry matter, more crude lipid content, and stronger ability to scavenge free radicals than WSO. The altered metabolites of glycerophospholipids, fatty acyls, and steroids revealed different regulatory mechanisms of lipids. The correlation analysis of metabolomics and previously published RNAseq data suggested that BSO and WSO mainly differed in the basal metabolic processes, such as lipid, amino acid and purine metabolisms. This study provides insights into the changes in the physiological indictors and the metabolites of oysters with varying melanin content.Keywords：Crassostrea gigas;UPLC-MS metabolomics;physiological indicators;melanin;shell color4|0|2Updated：2023-05-20
- Abstract：Haliotis discus hannai is an important marine economic species in China. Its egg color was found to be associated with economic traits, which provides a new idea for breeding. However, the molecular mechanism of the egg-color formation has not been reported. Thus, the pigment composition and comparative transcriptome analyses of H. discus hannai with green and gray egg color were conducted using high-performance liquid chromatography (HPLC) and RNA-Seq methods. Results show that individuals with green and gray eggs both possess the fucoxanthin. Lutein existed in gray-egged individuals, but not in green-egged individuals. In transcriptome analysis, 272 310 unigenes were received from 461 162 transcripts with a mean length of 985 bp and N50 of 1 524 bp, respectively. A total of 185 unigenes were identified as differentially expressed genes (DEGs). The DEGs involved in "flavin-containing compound metabolic process", "melanosome", "glutathione metabolism", and "cytochrome b6f complex" were likely related to the formation of the egg color. Our results provide foundational information for the functional analysis of egg-color related genes and are beneficial to the selective breeding of H. discus hannai.Keywords：Haliotis discus hannai;egg color;high-performance liquid chromatography;transcriptome;differentially expressed genes4|0|0Updated：2023-05-20
- Abstract：Gracilariopsis lemaneiformis is an economically-valued species and widely cultured in China at present. After being acclimated to different growth temperatures (15, 20, 25, and 30℃) for 7 days, the relative growth rate (RGR), nitrate reductase activity, soluble protein content and chlorophyll a fluorescence of G. lemaneiformis were examined. Results show that RGR was markedly affected by temperature especially at 20℃ at which G. lemaneiformis exhibited the highest effective quantum yield of PSⅡ[Y(Ⅱ)] and lightsaturated electron transport rate (ETRmax), but the lowest non-photochemical quenching. Irrespective of growth temperature, the nitrate reductase activity increased with the incubation temperature from 15 to 30℃. In addition, the greatest nitrate reductase activity was found in the thalli grown at 20℃. The value of temperature coefficient Q10 of alga cultured in 15℃ was the greatest among those of other temperatures tested. Results indicate that the optimum temperature for nitrate reductase synthesis was relatively lower than that for nitrate reductase activity, and the relationship among growth, photosynthesis, and nitrate reductase activity showed that the optimum temperature for activity of nitrate reductase in vivo assay should be the same to the optimal growth temperature.Keywords：chlorophyll a fluorescence;Gracilariopsis lemaneiformis;growth;nitrate reductase activity4|0|2Updated：2023-05-20
- Abstract：Length-weight relationship provides basic information of a fish's condition while the morphometric data of otolith has been traditionally used to determine the range of fish sizes for various purposes. The length-weight relationship of Terapon jarbua (Forskål, 1775) was examined from 165 specimens, while 132 specimens were used in sagittal otolith biometry measurements. Fish specimens were obtained from various locations in Malaysia including Pahang, Selangor, Sarawak, and Sabah. The total length of fish ranged 12.5-32.5 cm, while the total weight ranged 26.28-444.30 g. The otolith length ranged 0.423-1.070 cm, and the otolith weight was 0.010 3-0.157 2 g. The specimens displayed a mixture of positive and negative allometry growth as indicated by fluctuating b values between 2.74 and 3.15. The overall coefficient of determination (R2) between fish length and weight was 0.972 9, which implies a strong correlation. All regressions between the fish length and otolith dimensions were highly significant (P < 0.001). The otolith dimensions found to be most closely related to the fish total length was the otolith weight. This was supported by the regression model showing a high R2 value of 86.57%. The aspect ratio of otolith was 1.80±0.14 (mean±SD). Results confirm that the otolith growth reflects the somatic growth of T. jarbua. The length-weight relationship explained the growth conditions of the fishes in each location while the overall b value of 2.91 indicates that the condition of T. jarbua grown in Malaysian waters during the study period was generally in good condition. This study contributed to the database on the morphometric data of otolith of T. jarbua as well as the first report on fish length-weight relationship for T. jarbua in Malaysia.Keywords：aspect ratio;otolith;length-weight relationship;grunter4|0|0Updated：2023-05-20
Aquaculture and Fisheries
Erratum
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