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Volume 42 ， Issue 2 ， 2024
- Abstract：Coastal upwelling is significant for marine ecosystems by lifting nutrient-rich deep waters into the euphotic zone, thereby increasing primary and secondary productivity. The satellite observations show that the northern Arafura Sea (NAS), especially in the coastal region, features high chlorophyll-a (chl-a) concentrations, implying a strong coastal upwelling. However, coastal upwelling in the NAS has not received much attention. Based on a semi-automatic image processing technology, the seasonal and interannual variability of coastal upwelling in the NAS are investigated in this study using satellite-observed sea surface temperature (SST) and wind data. The results suggest that there are seasonal coastal upwelling events in the NAS modulated by upwelling-favorable southeast monsoon (SEM). The annual mean days, mean area, and annual mean intensity of coastal upwelling events during the SEM season are 92 days, 6 514 km2, and -5.31×105, respectively, while the corresponding values during the northwest monsoon (NWM) season are 32 days, 5 569 km2, and -1.41×105. It is also found that the SEM coastal upwelling in the NAS displays prominent interannual variability. The strong upwelling events are found in 2010, 2013, 2016, and 2017 when the southeast monsoon winds were weaker. Further analysis suggests that at the interannual scale, the upwelling index (UI) averaged in the SEM season is negatively correlated with that of three upwelling indicators. This can be attributed to the limitation of onshore geostrophic flow which is evidenced by the negative correlation between the UI and the alongshore difference in sea surface height. This study highlights the important role of the southeast monsoon in the temporal variability of coastal upwelling in the NAS.Keywords：coastal upwelling;the northern Arafura Sea;southeast monsoon;interannual variability33|26|0Updated：2024-10-11
- Abstract：Accurately estimating the ocean subsurface salinity structure (OSSS) is crucial for understanding ocean dynamics and predicting climate variations. We present a convolutional neural network (CNN) model to estimate the OSSS in the Indian Ocean using satellite data and Argo observations. We evaluated the performance of the CNN model in terms of its vertical and spatial distribution, as well as seasonal variation of OSSS estimation. Results demonstrate that the CNN model accurately estimates the most significant salinity features in the Indian Ocean using sea surface data with no significant differences from Argo-derived OSSS. However, the estimation accuracy of the CNN model varies with depth, with the most challenging depth being approximately 70 m, corresponding to the halocline layer. Validations of the CNN model’s accuracy in estimating OSSS in the Indian Ocean are also conducted by comparing Argo observations and CNN model estimations along two selected sections and four selected boxes. The results show that the CNN model effectively captures the seasonal variability of salinity, demonstrating its high performance in salinity estimation using sea surface data. Our analysis reveals that sea surface salinity has the strongest correlation with OSSS in shallow layers, while sea surface height anomaly plays a more significant role in deeper layers. These preliminary results provide valuable insights into the feasibility of estimating OSSS using satellite observations and have implications for studying upper ocean dynamics using machine learning techniques.Keywords：machine learning;convolutional neural network (CNN);ocean subsurface salinity structure (OSSS);Indian Ocean;satellite observations66|25|1Updated：2024-10-11
- Abstract：Chlorophyll-a (Chl-a) concentration is a primary indicator for marine environmental monitoring. The spatio-temporal variations of sea surface Chl-a concentration in the Yellow Sea (YS) and the East China Sea (ECS) in 2001–2020 were investigated by reconstructing the MODIS Level 3 products with the data interpolation empirical orthogonal function (DINEOF) method. The reconstructed results by interpolating the combined MODIS daily +8-day datasets were found better than those merely by interpolating daily or 8-day data. Chl-a concentration in the YS and the ECS reached its maximum in spring, with blooms occurring, decreased in summer and autumn, and increased in late autumn and early winter. By performing empirical orthogonal function (EOF) decomposition of the reconstructed data fields and correlation analysis with several potential environmental factors, we found that the sea surface temperature (SST) plays a significant role in the seasonal variation of Chl a, especially during spring and summer. The increase of SST in spring and the upper-layer nutrients mixed up during the last winter might favor the occurrence of spring blooms. The high sea surface temperature (SST) throughout the summer would strengthen the vertical stratification and prevent nutrients supply from deep water, resulting in low surface Chl-a concentrations. The sea surface Chl-a concentration in the YS was found decreased significantly from 2012 to 2020, which was possibly related to the Pacific Decadal Oscillation (PDO).Keywords：chlorophyll a (Chl a);data interpolation empirical orthogonal function (DINEOF);empirical orthogonal function (EOF) analysis;Yellow Sea;East China Sea27|23|0Updated：2024-10-11
- Abstract：Optical remote sensing has been widely used to study internal solitary waves (ISWs). Wind speed has an important effect on ISW imaging of optical remote sensing. The light and dark bands of ISWs cannot be observed by optical remote sensing when the wind is too strong. The relationship between the characteristics of ISWs bands in optical remote sensing images and the wind speed is still unclear. The influence of wind speeds on the characteristics of the ISWs bands is investigated based on the physical simulation experiments with the wind speeds of 1.6, 3.1, 3.5, 3.8, and 3.9 m/s. The experimental results show that when the wind speed is 3.9 m/s, the ISWs bands cannot be observed in optical remote sensing images with the stratification of h1∶h2=7∶58, ρ1∶ρ2=1∶1.04. When the wind speeds are 3.1, 3.5, and 3.8 m/s, which is lower than 3.9 m/s, the ISWs bands can be obtained in the simulated optical remote sensing image. The location of the band’s dark and light extremum and the band’s peak-to-peak spacing are almost not affected by wind speed. More-significant wind speeds can cause a greater gray difference of the light-dark bands. This provided a scientific basis for further understanding of ISW optical remote sensing imaging.Keywords：internal solitary wave (ISW);optical remote sensing;wind speed;characteristics of ISWs bands17|23|0Updated：2024-10-11
- Abstract：The dynamic parameters for internal solitary waves (ISWs) derived from the extended Korteweg-de Vries (eKdV) equation play an important role in the understanding and prediction of ISWs. The spatiotemporal variations of the dynamic parameters of the ISWs in the northern South China Sea (SCS) were studied based on the reanalysis of long-term temperature and salinity datasets. The results for spectrum analysis show that there are definite geographical differences for the periodic variation of the parameters: in shallow water, all parameters vary with a wave period of one year, while in deep water wave components of the parameters at other frequencies exist. Using wavelet analysis, the wavelet power spectral densities in deep water exhibited an inter-annual variation pattern. For example, the wave component of the dispersion coefficient with a wave period of about half a year reached its power peak once every two years. Based on previous work, this inter-annual variation pattern was deduced to be caused by dynamic processes. In further work on the regulatory mechanisms, empirical orthogonal function (EOF) decomposition was performed. It was found that the modes of the dispersion coefficient have different geographical distributions, explaining the reason why the wave components in different frequencies appeared in different locations. The numerical simulation results confirm that the variations in the parameters of the ISWs derived from the eKdV equation could affect the waveforms significantly because of changes in the polarity of the ISWs. Therefore, the periodic variations of the dynamic parameters are related to the geographical location because of dynamic processes operating.Keywords：internal solitary waves (ISWs);dynamic parameters;eKdV equation;spatiotemporal variation;polarity;empirical orthogonal function (EOF) decomposition18|23|0Updated：2024-10-11
- Abstract：The subtropical North and South Pacific Meridional Modes (NPMM and SPMM) are well known precursors of El Niño-Southern Oscillation (ENSO). However, relationship between them is not constant. In the early 1980, the relationship experienced an interdecadal transition. Changes in this connection can be attributed mainly to the phase change of the Pacific decadal oscillation (PDO). During the positive phase of PDO, a shallower thermocline in the central Pacific is responsible for the stronger trade wind charging (TWC) mechanism, which leads to a stronger equatorial subsurface temperature evolution. This dynamic process strengthens the connection between NPMM and ENSO. Associated with the negative phase of PDO, a shallower thermocline over southeastern Pacific allows an enhanced wind-evaporation-SST (WES) feedback, strengthening the connection between SPMM and ENSO. Using 35 Coupled Model Intercomparison Project Phase 6 (CMIP6) models, we examined the NPMM/SPMM performance and its connection with ENSO in the historical runs. The great majority of CMIP6 models can reproduce the pattern of NPMM and SPMM well, but they reveal discrepant ENSO and NPMM/SPMM relationship. The intermodal uncertainty for the connection of NPMM-ENSO is due to different TWC mechanism. A stronger TWC mechanism will enhance NPMM forcing. For SPMM, few models can simulate a good relationship with ENSO. The intermodel spread in the relationship of SPMM and ENSO owing to SST bias in the southeastern Pacific, as WES feedback is stronger when the southeastern Pacific is warmer.Keywords：North and South Pacific Meridional Modes (NPMM and SPMM);El Niño-Southern Oscillation (ENSO);Pacific Decadal Oscillation (PDO);Coupled Model Intercomparison Project Phase 6 (CMIP6)16|21|1Updated：2024-10-11
- Abstract：Atlantic meridional overturning circulation (AMOC) plays an important role in transporting heat meridionally in the Earth’s climate system and is also a key metrical tool to verify oceanic general circulation models. Two OMIP (Ocean Model Intercomparison Project phase 1 and 2) simulations with LICOM3 (version 3 of the LASG/IAP Climate System Ocean Model) developed at the State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics (LASG), Institute of Atmospheric Physics (IAP), are compared in this study. Both simulations well reproduce the fundamental characteristics of the AMOC, but the OMIP1 simulation shows a significantly stronger AMOC than the OMIP2 simulation. Because the LICOM3 configurations are identical between these two experiments, any differences between them must be attributed to the surface forcing data. Further analysis suggests that sea surface salinity (SSS) differences should be mainly responsible for the enhanced AMOC in the OMIP1 simulation, but sea surface temperature (SST) also play an unignorable role in modulating AMOC. In the North Atlantic, where deep convection occurs, the SSS in OMIP1 is more saline than that in OMIP1. We find that in the major region of deep convection, the change of SSS has more significant effect on density than the change of SST. As a result, the SSS was more saline than that in OMIP2, leading to stronger deep convection and subsequently intensify the AMOC. We conduct a series of numerical experiments with LICOM3, and the results confirmed that the changes in SSS have more significant effect on the strength of AMOC than the changes in SST.Keywords：oceanic general circulation model (OGCM);Atlantic meridional overturning (AMOC);surface forcing;deep convection16|19|0Updated：2024-10-11
- Abstract：Insufficient observations near the origin of the Kuroshio have led to incomplete understanding of the intraseasonal variability (ISV) of the Kuroshio. Direct measurements of the Kuroshio velocity were performed with an array of three profiler moorings (122.7°E, 123°E, and 123.3°E) along 18°N from January 2018 to February 2020. The ISV of the Kuroshio at 18°N was investigated based on a combination of mooring observations and global high-resolution HYbrid Coordinate Ocean Model reanalysis data. The estimated time-averaged transport in the upper 350 m across the observation transect was 6.5±2.6 Sv (1.0 Sv=106 m3/s). Two significant ISV peaks at 50–60 and ~100 d were recognized in the power spectra of the meridional velocity and transport. Further analysis indicated that the ISV at 50–60 d was caused by westward-propagating eddies at average propagation speed of ~13 cm/s and wavelength of ~635 km. Another ISV peak at ~100 d was mainly caused by northward-propagating eddies generated in the North Equatorial Current region. Further investigation indicated that the ISV of the Kuroshio at 18°N is dominated by meridional transport, rather than by the zonal migration of the Kuroshio main axis. Our findings provide a better understanding of the ISV of the Kuroshio east of Luzon Island.Keywords：intraseasonal variability (ISV);Kuroshio;mooring observation;eddy26|21|0Updated：2024-10-11
- Abstract：The basic structure and intraseasonal evolution of currents in the southeastern Andaman Sea was analyzed based on data collected in 2017 from two subsurface moorings (C1 and C5). Periodic variation in the upper ocean currents of the Andaman Sea was investigated by combining observational and satellite data. Mooring observations show that rapid changes of current speed and direction occurred in May and June, with a significant increase in current velocity at the C1 mooring. In the second half of the year, southward flow dominated at the C1 mooring, and alternating northward and southward flows were evident at the C5 mooring during the same period but the northward flow prevailed in boreal winter. In addition, analysis of the power spectra of the upper currents revealed that the tidal period at both moorings is primarily semidiurnal with weaker energy than that of the low-frequency currents. The upper ocean currents at the C1 and C5 moorings exhibited intraseasonal variation of 30–60 d and 120 d, while the zonal current at the C1 mooring exhibited a notable period of approximately 180 d. Further analysis indicated that the variability of currents in the Andaman Sea is influenced primarily by equatorial Kelvin waves and Rossby wave packets. Moreover, our results suggest that equatorial Kelvin waves from the eastern Indian Ocean entered the Andaman Sea in the form of Wyrtki Jets and propagated primarily along two distinct pathways during the observation period. In addition to coastal boundary Kelvin waves, it was found that a branch of the Wyrtki Jet that directly enters the Andaman Sea and flows northward along the slope of the continental shelf, and reflected Rossby wave packets by topography.Keywords：mooring observation;Wyrtki Jet;Rossby waves;intraseasonal variation15|19|0Updated：2024-10-11
- Abstract：A recent study by Liu et al. (2020) suggested that due to the saturation of equatorially trapped planetary waves with different dynamical types, temporal periods, meridional and baroclinic modes, complex layer structures of vertical velocity shear and hence turbulent mixing could frequently occur in the thermocline of the eastern equatorial Pacific. We investigated the occurrence of the interior turbulent mixing as indicated by shear instabilities, above the Equatorial Undercurrent (EUC) core at three equatorial sites along 140°W, 170°W, and 165°E, respectively, based mainly on data from the Tropical Atmosphere and Ocean (TAO) mooring array. We found that turbulent mixing bursts persisted in the thermocline of all three sites. Specifically, the interior turbulent mixing layers (ITMLs) could occur in probability of approximately 68%, 53%, and 48% at the three sites, respectively. The overall occurrence probability shows obvious and similar biannual variations at 140°W and 170°W, which is higher in boreal from late summer to winter and lower in spring. Vertically, the ITMLs are primarily located above the EUC core and prevail in deeper (shallower) layers from late summer to winter (spring). Most ITMLs (70%) lasted for hours to 3 days, and a few of them (15%) for more than 7 days. The thicknesses of ITMLs were concentrated between 15 and 55 m. At 165°E, the vertical distribution of ITML occurrence probability was different from that at 140°W and 170°W, as it did not show a preference for depths; the durations of ITMLs are short (also from hours to several days) and their thicknesses were between 5 and 25 m. These properties, particularly the high occurrence probability, and short durations demonstrated the persistence of thermocline mixing in the western to eastern equatorial Pacific thermocline and confirmed the generation mechanism by persistent equatorial waves as well.Keywords：interior turbulent mixing layer (ITML);weakly sheared layer (WSL);Equatorial Undercurrent (EUC) core;occurrence probability;seasonality15|15|0Updated：2024-10-11
- Abstract：Major differences in beach erosion between two neighboring artificial beaches Xiangluwan Beach (XL beach) and Meiliwan Beach (ML beach) in Zhuhai, China, were studied after Super Typhoon Hato. In this study, a fully nonlinear Boussinesq wave model (FUNWAVE)-Total Variation Diminishing (TVD) was used to distinguish the main impact factors, their relative contributions, and the hydrodynamic mechanisms underlying the different beach responses. Results show that compared to the ML beach, the main reason for the relatively weak erosion on Xiangluwan (XL) beach was the smaller beach berm height (accounting for approximately 75.9% of the erosion response). Regarding the beach with a higher berm, the stronger wave-induced undertow flow, along with the higher sediment concentration, led to a higher offshore sediment transport flux, resulting in more severe erosion relative to the beach with a smaller berm height. The second most important reason explaining the weak erosion on XL beach was the absence of seawalls (accounting for approximately 17.9% of the erosion response). Wave reflection induced by the seawall could cause higher suspended sediment concentration, resulting in a toe scouring near the seawall. The offshore submerged breakwater protected XL beach slightly (accounting for approximately 6.1% of the erosion response). Due to the higher water level induced by storm surge, most of the wave energy could penetrate through the submerged breakwater. The effect of the larger berm width of XL beach was negligible. Compared to the beach with a larger berm width, the erosion/deposition regions in the beach with a narrower berm width showed shoreward migration, without significant changes in the erosion/deposition extent. Despite of this, the larger berm width could reduce the wave energy reaching the shoreline. This study of the storm stability of artificial beaches may be applied to beach restoration design.Keywords：beach erosion;berm height;berm width;seawall;fully nonlinear Boussinesq wave model (FUNWAVE)18|8|0Updated：2024-10-11
Physics
- Abstract：Deep-sea mining activities can potentially release metals, which pose a toxicological threat to deep-sea ecosystems. Nevertheless, due to the remoteness and inaccessibility of the deep-sea biosphere, there is insufficient knowledge about the impact of metal exposure on its inhabitants. In this study, deep-sea mussel Gigantidas platifrons, a commonly used deep-sea toxicology model organism, was exposed to manganese (100, 1 000 µg/L) or iron (500, 5 000 µg/L) for 7 d, respectively. Manganese and iron were chosen for their high levels of occurrence within deep-sea deposits. Metal accumulation and a battery of biochemical biomarkers related to antioxidative stress in superoxide dismutase (SOD), catalase (CAT), malondialdehyde (MDA); immune function in alkaline phosphatase (AKP), acid phosphatase (ACP); and energy metabolism in pyruvate kinase (PK) and hexokinase (HK) were assessed in mussel gills. Results showed that deep-sea mussel G. platifrons exhibited a high capacity to accumulate Mn/Fe. In addition, most tested biochemical parameters were altered by metal exposure, demonstrating that metals could induce oxidative stress, suppress the immune system, and affect energy metabolism of deep-sea mussels. The integrated biomarker response (IBR) approach indicated that the exposure to Mn/Fe had a negative impact on deep-sea mussels, and Mn demonstrated a more harmful impact on deep-sea mussels than Fe. Additionally, SOD and CAT biomarkers had the greatest impact on IBR values in Mn treatments, while ACP and HK were most influential for the low- and high-dose Fe groups, respectively. This study represents the first application of the IBR approach to evaluate the toxicity of metals on deep-sea fauna and serves as a crucial framework for risk assessment of deep-sea mining-associated metal exposure.Keywords：mussel;metal;deep-sea mining;biomarker;environmental monitoring17|5|0Updated：2024-10-11
- Abstract：Ulva prolifera is the causative species of the annually occurring large-scale green tides in China since 2007. Its specific biological features on reproductivity strategies, as well as intra-species genetic diversity, are still largely unknown, especially at the genome level, despite their importance in understanding the formation and outbreak of massive green tides. In the present study, the restriction site-associated DNA genotyping approach (2b-RAD) was adopted to identify the genome-wide single-nucleotide polymorphisms (SNPs) of 54 individual thalli including samples collected from Subei Shoal in 2019 and Qingdao coast from 2019 to 2021. SNPs genotype results revealed that most of the thalli in 2019 and 2020 were haploid gametophytes, while only half of the thalli were gametophytes in 2021, indicating flexibility in the reproductive strategies for the formation of the green tides among different years and the dominance of asexual and vegetative reproductive mode for the floating period. Besides, population analysis was conducted, and it revealed a very low genetic diversity among samples from Subei Shoal and the Qingdao coast in the same year and a higher divergence among samples in different years. The results showed the efficiency of 2b-RAD in the exploration of SNPs in U. prolifera and provided the first genome-wide scale evidence for the origin of the large-scale green tides on the Qingdao coast. This study improved our understanding of the reproductive strategy and genetic diversity of the green tide causative species and will help further reveal the biological causes of the green tide in China.Keywords：green tide;Ulva prolifera;2b-RAD;single-nucleotide polymorphism (SNP);reproductive strategy;genetic diversity14|4|0Updated：2024-10-11
- Abstract：The estuarine areas are under frequent influence from freshwater intrusion and ocean currents, in which zooplankton species are diversified and variable as they are sensitive to physio-chemical variations in water. Therefore, understanding the relationships between zooplankton and environmental factors help us know the water quality. To achieve co-existence with species in similar ecological group or habit, they could inevitably alter themselves to fit the ecology and adjust the function according to the competitive exclusion in ecological theory. However, information of the co-existence of dominant species in the Changjiang (Yangtze) River estuary (CRE) and adjacent waters remains scarce. We explored the relationships between dominant zooplankton and environmental factors in the study region in spring-summer from 2016 to 2020, involving particularly the composition of dominant species, ecological groups, their relationships with environmental factors, and co-existence of important species, using the non-multidimensional scale analysis (nMDS) method and redundancy analysis. Results show that Labidocera euchaeta and Tortanus vermiculus were dominant species in the study scope. The turnover rate of dominant zooplankton was greater (>50%) in spring while the species number was higher in summer. The dominant species were estuarine, offshore, and eurytopic based on the adaptation to salinity. In spring, the ecological groups were dominated by estuarine species, while in summer by estuarine and offshore species. In addition, the nMDS showed that the dominant species in the same ecological group were more dispersed and not prominently clustered; the dominant species were staggered among different ecological groups. The temperature, salinity, pH, dissolved oxygen, and chlorophyll a were the main environmental factors on the distribution of the dominant species in spring, while in summer were dissolved oxygen, temperature, salinity, and pH. The domination of medusae of Nemopsis bachei and Pleurobrachia globosa in zooplankton community in spring, and the continuous decrease in abundance of L. euchaeta reflected the effects of local climate change. The temperature and salinity changes in different years and the subsequent response of zooplankton reflected the influence of freshwater intrusion and/or ocean currents. Zooplankton in similar ecological habits exhibited the competitive exclusion in terms of co-existence.Keywords：Changjiang River estuary (CRE);zooplankton;dominant species;ecological group;environmental factor;co-existence17|7|0Updated：2024-10-11
- Abstract：Cometabolic degradation is currently an effective and extensively way to remove high molecular weight polycyclic aromatic hydrocarbons (HMW-PAHs). Unfortunately, due to low bio-accessibility and high biotoxicity, the cometabolic degradation rate of HMW-PAHs is limited. Glycine-β-cyclodextrin (GCD) was obtained through amino modification of β-cyclodextrin (BCD) and added to cometabolic system of phenanthrene (PHE) and pyrene (PYR) to assist PYR biodegradation. Results show that the addition of GCD (100 mg/L) effectively improved the removal rate of PYR (20 mg/L) by 42.3%. GCD appeared to increase the bio-accessibility and reduce the biotoxicity of PHE and PYR, and then promoted the growth of Pseudomonas stutzeri DJP1 and stimulated the elevation of dehydrogenase (DHA) and catechol 12 dioxygenase (C12O) activities. The phthalate metabolic pathway was accelerated, which improved the cometabolic degradation. This study provided a new reference for the cometabolic degradation of HMW-PAHs.Keywords：cometabolism;phenanthrene;pyrene;glycine-β-cyclodextrin;biological accessibility;biotoxicity16|5|0Updated：2024-10-11
Ecology
- Abstract：The function of exogenous alanine (Ala) in regulating biomass accumulation, lipid production, photosynthesis, and respiration in Chlorella pyrenoidosa was studied. Result shows that the supplementation of Ala increased C. pyrenoidosa biomass and lipid production in an 8-d batch culture. The concentration of 10 mmol/L of Ala was optimum and increased the microalgal cell biomass and lipid content by 39.3% and 21.4%, respectively, compared with that in the control (0-mmol/L Ala). Ala supplementation reduced photosynthetic activity while boosting respiratory activity and pyruvate levels, indicating that C. pyrenoidosa used exogenous Ala for biomass accumulation through the respiratory metabolic process. The accelerated respiratory metabolism due to Ala supplementation elevated the substrate pool and improved the lipogenic gene expression, promoting lipid production at last. This study provided a novel method for increasing biomass accumulation and lipid production and elucidated the role of Ala in regulating lipid production.Keywords：alanine;Chlorella pyrenoidosa;lipid;respiration;lipogenic gene14|5|0Updated：2024-10-11
- Abstract：The Tbx family is first known through the study of their functions in the body and limbs, and its members Tbx4 and Tbx5 genes are important factors in determining the characteristics of the appendages. Pampus argenteus is one of the important economical marine fishes widely distributed in offshore areas. Therefore, it is necessary to study the role of Tbx family genes in the deletion of pelvic fin in P. argenteus. In this study, we cloned Tbx4 and Tbx5 cDNA sequence of P. argenteus (GenBank: MH709128 and MH712458). The Western blot and real time PCR were used to detect the expressions of Tbx4 and Tbx5 in different developmental stages and tissues of P. argenteus. In addition, whole-mount in-situ hybridization was used to study the localization of Tbx4 and Tbx5 genes in different developmental stages of P. argenteus. Results show that the translation of Tbx4 mRNA was inhibited during the critical period of pelvic fin development. Among different tissues, Tbx4 protein levels were the lowest in the abdominal epithelium, and even lower than that in the pectoral fin, suggesting that the protein expression was also inhibited in the abdominal epithelium of adult P. argenteus. Therefore, the results indicated that upstream genes regulation led to the key stage-specific and low expression of Tbx4 during pelvic fin development and in the abdominal epithelium.Keywords：Stromateidae;pelvic fin;protein translation;T-box;aquaculture;broodstock24|4|0Updated：2024-10-11
- Abstract：Global warming threatens freshwater ecosystems and compromises fish survival. To elucidate the role of miRNAs in the livers of heat stressed largemouth bass, juvenile fish was subject to heat stress under 37 °C. Both mRNA-seq and miRNA-seq were conducted on the liver tissues under control and heat stress conditions. Differential gene expression analysis and enrichment analysis were performed on mRNA and miRNA expression profiles. A total of 406 differentially expressed genes (DEGs) were discovered, of which 212 were up-regulated and 194 were down-regulated. Most of the DEGs were significantly implicated in the regulation of “protein processing in endoplasmic reticulum”, “proteasome”, “steroid biosynthesis”, and “ornithine decarboxylase inhibitor activity” pathways. In addition, 47 differentially expressed miRNAs (DEMs) were identified in largemouth bass livers under heat stress, including 21 up-regulated and 25 down-regulated miRNAs. A negatively regulated miRNA-mRNA network including 12 miRNAs and 19 mRNAs was constructed with DEMs involved in “protein degradation”, “calcium ion regulation”, “cell apoptosis”, and “lipid metabolism”. Moreover, this study indicated novel-miR-144 activated the IRE1 signaling pathway by targeting txndc5 to induce liver apoptosis in largemouth bass under heat stress. This study revealed the involvement of miRNA regulation in largemouth bass in response to heat stress.Keywords：heat stress;largemouth bass;miRNA-mRNA interaction10|4|0Updated：2024-10-11
- Abstract：The giant freshwater prawn Macrobrachium rosenbergii distributed from tropical to subtropical regions, is a warm-water species, and its survival temperature is 14–35 °C, which greatly limits its culture cycle and culture area in China. Therefore, it is urgent to cultivate a new high quality, high yield variety with improved cold-resistance, but the genetic parameters for cold-resistance traits are unknown in M. rosenbergii. In this study, the cold-resistance of adult M. rosenbergii populations was tested using the indoor artificial cooling method. Individuals were selected from 139 families of Shufeng G3 generation and cultured for 200 days. A linear mixed model was constructed by ASReml-R to evaluate the genetic parameters of the cold-resistance trait (cooling degree hours, CDH) and growth traits (body weight, BW, and body length, BL) based on the restricted maximum likelihood (REML) method. The results show that the heritability of CDH was low (0.12±0.05), while the growth traits (BW and BL) had low to moderate heritability, with 0.20±0.06 for BW and 0.06±0.04 for BL. The phenotypic and genetic correlation between BW and BL was significantly positive, but significantly negative phenotypic and genetic correlations were detected between CDH and BW and between CDH and BL. Furthermore, the analysis of the differences between cold-resistance and phenotypic traits showed that the female reproductive status, exoskeleton hardness and claw number of adult prawns had a great influence on the cold-resistance of M. rosenbergii (P<0.05), indicating that adults with claws and hard exoskeletons are preferred as parents in subsequent breeding selection. The present results can be attributed to the selection and breeding of a new cold-resistant variety of M. rosenbergii.Keywords：cold-resistance;growth traits;heritability;correlation;Macrobrachium rosenbergii16|7|0Updated：2024-10-11
- Abstract：Homeodomains, a 60-amino acid sequence encoded by 180 nucleotides, are highly conserved DNA-binding motifs that are present in a variety of transcription factors in species ranging from yeast to humans. The NKX proteins belong to the homeodomain (HD)-containing transcription factor family. They play vital roles in the regulation of morphogenesis. NKX1-2 is one member of the NKX subfamily. At present, information about its nuclear localization signal (NLS) sequence is limited. We studied the NLS sequence of zebrafish Nkx1.2 by introducing sequence changes such as deletion, mutation, and truncation, and identified an NLS motif (QNRRTKWKKQ) that is localized at the C-terminus of the homeodomain. Moreover, the deletion of two amino acid residues (RR) in this NLS motif prevents Nkx1.2 from entering the nucleus, indicating that the two amino acids are essential for Nkx1.2 nuclear localization. However, the NLS motif alone is unable to target cytoplasmic protein glutathione S-transferase (GST) to the nucleus. An intact homeodomain is necessary for mediating the complete nuclear transport of cytoplasmic protein. Unlike most nuclear import proteins with short NLS sequences, a long NLS is present in zebrafish Nkx1.2. We also demonstrated that the sequences of homeodomain of NKX1.2 are well conserved among different species. This study is informative to verify the function of the NKX1.2 protein.Keywords：NKX1.2;NKX protein;homeodomain;nuclear localization signal (NLS);nuclear transport15|4|0Updated：2024-10-11
- Abstract：Four species new to science were identified in the Tellinidae museum collections in the Marine Biological Museum of Chinese Academy of Sciences. Pinguitellina triquetra sp. nov., collected in 1981, has not previously been described or reported. It differs from other Pinguitellina species by its trigonal shape, rose-colored valve interior, and deep and wide pallial sinus, which is confluent with the pallial line. Pinguitellina protuberangla sp. nov. has a broad and deep dorsal corner, short and straight posterodorsal margin, comparatively large adductor scars, depressed and fragile shells, and deep socket at the anterior edge of the right valve. Pinguitellina minuta sp. nov. was previously misidentified as Arcopella casta in China. It is a new species based on its unique characteristics, which include small, fragile, inflated, translucent, and triangularly ovate-shaped shells with acuminated and convex umboes. As the first species described in China within the genus Abranda Iredale, 1924, Abranda xui sp. nov. has internal ligaments and thin, fragile, and translucent elliptical shells with fine radials on the surface. In this study, we reorganized the species currently contained in the two genera Pinguitellina and Abranda and created keys to the known species. We believe that numerous collected bivalve specimens have been overlooked in the South China Sea, and to date, mollusk has not been adequately sampled. Thus, further exploration and analysis are required to understand species diversity in this area.Keywords：Abranda;morphology;Pinguitellina;species diversity;taxonomy;Tellinidae31|5|0Updated：2024-10-11
- Abstract：The first record of abnormal body coloration in Sebastes koreanus Kim and Lee, 1994, from the Yellow Sea of China, was documented based on morphological characteristics and DNA barcoding. The two rockfish specimens were collected from the coastal waters of Qingdao, China, and the whole body and all fins of them were red. Of the two red-colored rockfish, there were tiny deep red spots on each fin, 2 red radial stripes behind and below the eyes and 1 large deep red blotch on the opercula, while the similar stripe and spot patterns are also present in the S. koreanus specimens with normal body coloration. The countable characteristics of the two specimens are in the range of the morphometry of S. koreanus. To further clarify the species identity and taxonomic status of the two specimens, DNA barcode analysis was carried out. The genetic distance between the red-colored rockfish and S. koreanus was 0, and the minimum net genetic distances between the red-colored rockfish and other Sebastes species except for S. koreanus were 3.0%, which exceeds the threshold of species delimitation. The phylogenetic analysis showed that the DNA barcoding sequences of the two red-colored rockfish clustered with the S. koreanus sequences. The above results of DNA barcode analysis also support that the two red-colored rockfish could be identified as the species of S. koreanus. The mechanism of color variation in S. koreanus is desirable for further research and the species could be an ideal model to study the color-driven speciation of the rockfishes.Keywords：abnormal body coloration;Sebastes koreanus;coastal water of China;Yellow Sea;morphological characteristics;DNA barcoding17|6|0Updated：2024-10-11
Biology
- Abstract：Scallop culture is an important way of bottom-seeding marine ranching, which is of great significance to improve the current situation of fishery resources. However, there are some problems in site-selection evaluation of marine ranching, such as imperfect criteria system, complex structure, untargeted criteria quantification, etc. In addition, no site-selection evaluation method of bottom-seeding culture areas for scallops is available. Therefore, we established a hierarchy structure model according to the analytic hierarchy process (AHP) theory, in which social, physical, chemical, and biological environments are used as main criteria, and marine functional zonation, water depth, current, water temperature, salinity, substrate type, water quality, sediment quality, red tide, phytoplankton, and zooplankton are used as sub-criteria, on which a multi-parameter evaluation system is set up. Meanwhile, the dualism method, assignment method, and membership function method were used to quantify sub-criteria, and a quantitative evaluation for the entire criteria was added, including the evaluation and analysis of two types of unsuitable environmental situations. By overall consideration in scallop yield, quality, and marine ranching construction objectives, the weight of the main criteria could be determined. Five grades in the suitability corresponding to the evaluation result were divided, and the Python language was used to create an evaluation system for efficient calculation and intuitive presentation of the evaluation outcome. Eight marine cases were simulated based on existing survey data, and the results prove that the method is feasible for evaluating and analyzing the site selection of bottom-seeding culture areas for scallops under various environmental situations. The proposed evaluation method can be promoted for the site selection of bottom-seeding marine ranching. This study provided theoretical and methodological references for the site selection evaluation of other types of marine ranching.Keywords：marine ranching;bottom-seeding scallops;site selection evaluation;analytic hierarchy process;evaluation system20|8|0Updated：2024-10-11
- Abstract：To identify the cause of mass mortality of adult Macrobrachium rosenbergii in a farm in Gaoyou City, Jiangsu Province, China, a dominant strain named DKQ-1 was isolated from the hepatopancreas of dying M. rosenbergii and identified as Aeromonas dhakensis by purification culture, biochemical characterization, and 16S rRNA and gyrB gene sequence analysis. The results of the challenge test revealed that the strain was highly pathogenic and the 50% lethal dose (LD50) in 72 h to M. rosenbergii was 1.54×105 CFU/mL. The amplification results of virulence genes show that strain DKQ-1 carried 9 virulence genes, including ascV, aexT, aer, act, lip, ompAI, gcaT, acg, and exu, supporting the strong virulence of strain DKQ-1 to M. rosenbergii. Histopathological observation of the hepatopancreas, gills, and intestines indicated that DKQ-1 injection into M. rosenbergii could cause serious tissue damage, which further supported the strong virulence of this strain. In addition, a drug susceptibility test revealed that strain DKQ-1 was sensitive to 16 kinds of antibiotics, resistant to 9 kinds of antibiotics, and had intermediate resistance to spectinomycin and kanamycin. This study is the first report of A. dhakensis isolated from M. rosenbergii and provided a reference for the pathogen identification of bacterial diseases in M. rosenbergii, and for the prevention and treatment caused by A. dhakensis.Keywords：Aeromonas dhakensis;histopathology;virulence gene;gyrB;drug susceptibility test;Macrobrachium rosenbergii23|12|0Updated：2024-10-11
- Abstract：Our previous study found that feeding with Lactobacillus plantarum Ep-M17 could effectively affect the growth performance, immune response, and gut microbiota of Penaeus vannamei. However, high temperature and pressure during feed pelletizing is the main problem that can lead to a decrease in the activity of probiotics or cause their inactivation. Further investigation needs to investigate whether inactivated Ep-M17 can exert similar effects as live Ep-M17. Therefore, we evaluated the effects of inactivated L. plantarum Ep-M17 on growth performance, immune response, disease resistance, and gut microbiota in P. vannamei. Results show that adding inactivated Ep-M17 to the feed also promoted body weight gain and increased relative immune protection in shrimp. Also, histological examination revealed that the administration of inactivated Ep-M17 led to improvements in the density and distribution of microvilli in the intestines and enhancements in the abundance of B and R cells in the hepatopancreas. Additionally, the inactivated Ep-M17 supplementation resulted in increased activity levels of nutrient immune-related enzymes in both the shrimp hepatopancreas and intestines. Moreover, it stimulated the expression of Lvlec, PEN-3a, Crustin, LGBP, Lysozyme, and proPo genes in both the hepatopancreas and intestines. Furthermore, the inactivated Ep-M17 also increased bacterial diversity in the gut of shrimp and promoted the abundance of specific flora, facilitating the host organism’s metabolism and immunity to improve the disease resistance of shrimp. Therefore, supplementation of inactivated L. plantarum Ep-M17 in shrimp diets can exert similar effects as live L. plantarum Ep-M17 effectively improving growth performance, gut microbiota, immune response, and disease resistance in P. vannamei.Keywords：Penaeus vannamei;Lactobacillus plantarum Ep-M17;inactivated probiotics;immune response;gut flora17|7|0Updated：2024-10-11
Aquaculture and Fisheries
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