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Volume 43 ， Issue 4 ， 2025
- Abstract：Numerical models are crucial for quantifying the ocean-atmosphere interactions associated with the El Niño-Southern Oscillation (ENSO) phenomenon in the tropical Pacific. Current coupled models often exhibit significant biases and inter-model differences in simulating ENSO, underscoring the need for alternative modeling approaches. The Regional Ocean Modeling System (ROMS) is a sophisticated ocean model widely used for regional studies and has been coupled with various atmospheric models. However, its application in simulating ENSO processes on a basin scale in the tropical Pacific has not been explored. For the first time, this study presents the development of a basin-scale hybrid coupled model (HCM) for the tropical Pacific, integrating ROMS with a statistical atmospheric model that captures the interannual relationships between sea surface temperature (SST) and wind stress anomalies. The HCM is evaluated for its capability to simulate the annual mean, seasonal, and interannual variations of the oceanic state in the tropical Pacific. Results demonstrate that the model effectively reproduces the ENSO cycle, with a dominant oscillation period of approximately two years. The ROMS-based HCM developed here offers an efficient and robust tool for investigating climate variability in the tropical Pacific.Keywords：Regional Ocean Modeling System (ROMS);statistical atmospheric model;hybrid coupled model;El Niño-Southern Oscillation (ENSO);model evaluation;tropical Pacific29|21|0Updated：2025-08-07
- Abstract：Convectively unstable processes caused by dense water subsidence are common occurrences in high-latitude oceanic regions, and significantly modulate mass and heat transport and mixing processes in the ocean. An idealized numerical experiment using the large eddy simulation method was conducted to analyze the three-dimensional flow field structure and the mechanism for dense water subsidence. Specifically, a negative salt flux is set at the sea surface, in which salt flux enters the sea surface to simulate the icing and salting-out phenomena that occur at high latitudes. Results show that the mean-state 3D flow field of dense water subsidence exhibits a hollow conical distribution. The horizontal flow field is characterized by a cyclonic vortex that driven primarily by the pressure gradient and influenced by the Coriolis effect. Moreover, the inverse vertical pressure gradient generated by this vortex inhibits the sinking of the plume, leading to its off-axis deflection and the development of an anticyclonic precession. In addition, the impact of rotation on the structure of a sinking plume within a stratified environment is discussed. Both horizontal vortex intensity and cone angle of the hollow cone flow field are increased with increasing rotation rate, resulting in a decrease in the plume’s maximum sinking depth. Variances in rotation direction cause the horizontal vortex and sinking plumes of dense water in the northern and southern hemispheres to rotate in opposite directions.Keywords：convectively unstable process;3D flow field;large eddy simulation (LES);rotation rate22|11|0Updated：2025-08-07
- Abstract：Variations in ocean mixed layer depth (MLD) show a significant impact on energy balance in the global climate systems and marine ecosystems. At present, the accuracy of modeling MLD, especially in the region with complex ocean dynamics, remains a challenge, thus calling for an emergency using artificial intelligence approach to improve the assessment of the MLD. A novel convolutional neural network model was developed based on a dual-attention module (DA-CNN) to estimate the MLD in the Bay of Bengal (BoB) by integrating multi-source remote sensing data and Argo gridded data. Compared with the original CNN model, the DA-CNN model exhibits superior performance with notable improvements in the annual average root mean square error (RMSE) and R2 values by 13.0% and 8.4%, respectively, while more accurately capturing the seasonal variations in MLD. Moreover, the results using the DA-CNN model show minimum RMSE and maximum R2 values, in comparison to the calculation by the random forest, artificial neural network model, and the hybrid coordinate ocean model. Accordingly, our findings suggest that the newly developed DA-CNN model provides an effective advantage in studying the MLD and the associated ocean processes.Keywords：mixed layer depth (MLD);remote sensing observation;dual-attention module (DA-CNN);Bay of Bengal19|14|0Updated：2025-08-07
- Abstract：Considering the difficulty of integrating the depth points of nautical charts of the East China Sea into a global high-precision Grid Digital Elevation Model (Grid-DEM), we proposed a “Fusion based on Image Recognition (FIR)” method for multi-sourced depth data fusion, and used it to merge the electronic nautical chart dataset (referred to as Chart2014 in this paper) with the global digital elevation dataset (referred to as Globalbath2002 in this paper). Compared to the traditional fusion of two datasets by direct combination and interpolation, the new Grid-DEM formed by FIR can better represent the data characteristics of Chart2014, reduce the calculation difficulty, and be more intuitive, and, the choice of different interpolation methods in FIR and the influence of the “exclusion radius R” parameter were discussed. FIR avoids complex calculations of spatial distances among points from different sources, and instead uses spatial exclusion map to perform one-step screening based on the exclusion radius R, which greatly improved the fusion status of a reliable dataset. The fusion results of different experiments were analyzed statistically with root mean square error and mean relative error, showing that the interpolation methods based on Delaunay triangulation are more suitable for the fusion of nautical chart depth of China, and factors such as the point density distribution of multiple source data, accuracy, interpolation method, and various terrain conditions should be fully considered when selecting the exclusion radius R.Keywords：water depth;fusion method;Grid Digital Elevation Model (Grid-DEM);image recognition;Delaunay triangulation17|12|0Updated：2025-08-07
- Abstract：Mesoscale eddies are widespread in the global ocean, significantly influencing the physical, chemical, and biological structures of water column. Based on the CTD data and suspended particulate matter (SPM) data collected at 36 hydrographic stations during a field cruise in southern Mozambique Channel, combined with satellite altimeter observations, we identified a series of mesoscale eddies traversing the Mozambique Channel. Our hydrographic measurements, coupled with in situ chlorophyll fluorescence data, reveal that these eddies significantly influence thermohaline structure and chlorophyll distribution, which in turn affects primary productivity and SPM concentrations in the upper ocean. The cyclonic eddies facilitate the upwelling of cold subsurface water, leading to a shallowing of the pycnocline and the creation of a low-temperature anomaly with variable salinity anomalies at different depths. Conversely, anticyclonic eddies submerge warm surface water, deepening the pycnocline, and resulting in a high-temperature anomaly accompanied by distinct salinity patterns. Significantly, a coastal anticyclonic eddy was observed to intercept terrestrial material from the Delagoa Bight, redirecting it west of 36°E. This study presents unique and quasi-synchronous CTD datasets capturing mesoscale eddy impacts, and provided valuable insights into SPM variability within the often-neglected southern Mozambique Channel.Keywords：mesoscale eddy;suspended particulate matter (SPM);organic carbon;chlorophyll concentration;Mozambique Channel13|12|0Updated：2025-08-07
Physics
- Abstract：Based on Moho and Curie depth, heat flow, and upper mantle S-wave velocity anomaly, we infer the thermo-chemical structure of the lithospheres in Africa and surrounding oceans. The Moho depth is derived from gravity anomaly using the Parker-Oldenburg method, with constraints from seismic Moho. Crustal stratification defined by Curie-Moho depth difference shows that thermal and strong compositional processes may have shaped the lithospheric architecture of the African continental plate. Moho and Curie depths indicate the southern and eastern African cratons have thermochemical structures different from the West African Craton. Large Curie-Moho depth difference in southern and eastern Africa aligns with the low velocity anomaly originated from the core-mantle boundary. Mantle upwelling from the African low-velocity anomaly presumably induced partial melting at great depth, and the release of mineral-rich fluid and large amounts of volatile components facilitates a regional metasomatism, and results in a depleted, predominantly felsic, low-density paramagnetic crust. Mantle xenolith in kimberlites and volcanic rocks supports metasomatism by melts transmitted through narrow conduits as an intermittent or continuous upward flux of mineral-rich fluid. Alignment of the Curie-Moho depth difference at the intra-plate volcanic province correlates with weak lithospheric strength along the corridor connecting the intra-plate volcanic province with the Ethiopian plateau, suggesting a pathway for thermochemical asthenospheric flow. Crustal stratification and compositional-driven density layering support crustal buoyancy and uplift in the Hoggar, and southern and eastern Africa. A magnetized uppermost mantle is prevalent in the entire oceanic region, except at large igneous provinces (LIPs), volcanic seamounts, and oceanic plateaus, which have partial paramagnetic crusts. Our results support thermochemical upwelling related to the low velocity anomaly beneath the African plate.Keywords：Moho Depth;Curie depth;thermochemical processes;Africa plate;Archean craton;crustal composition14|12|0Updated：2025-08-07
- Abstract：Focusing on the Zengmu-Beikang Basin in the southern South China Sea, we summarized the regional sequence stratigraphic framework and identified mass-transport complex (MTC) that had developed since the Late Miocene (10.5 Ma), by using high-resolution multibeam bathymetric and 2D seismic datasets. Based on the analysis of high amplitude and continuous seismic reflections within the mass-transport deposits (MTDs), we identified 14 basal shear surfaces (BSS) and divided the MTC into 14 units (MTD1–MTD14 from the youngest to the oldest in numerical order). Two types of seismic facies and five seismic features within the MTDs were recognized, including chaotic and transparent facies (debris flow), chaotic and semi-transparent facies (debris flow), thrust-fold systems, blocks, escarpments, pressure ridges, and normal faults. Analysis of the depositional area, frequency, and vertical extent of the escarpments of the fourteen MTD units revealed their variations in dimensions. Specifically, MTD14–MTD4 exhibited a gradual increase in the size of the deposition unit, with larger-sized MTD7–MTD4; while MTD3–MTD1 showed a gradual decrease in the size. The evolution of the MTDs in the study area is primarily controlled by several factors, including erosion of mass-movement processes (e.g., slide, slump, and mass flows), sea-level fluctuation and sediment supply, tectonic activity, development of mud diapirs, and topographic influence. It is also plausible that the large-sized MTD7–MTD4 might be formed in the Pliocene due to steep slope gradient and instability caused by the development of mud diapirs, whereas in the Quaternary, the influence of mud diapirs in the shallow strata diminished, and smaller-sized MTD3–MTD1 were formed.Keywords：mass-transport deposit (MTD);seismic interpretation;mud diapir;change in the size of MTD units10|11|0Updated：2025-08-07
Geology
- Abstract：Marine pollution is a well-recognized phenomenon that has many negative effects on the marine environment. The effects of marine pollution are due to the discharge of hazardous materials, toxins, or other pollutants into the marine environment, which includes seas, estuaries, oceans, and other water bodies, and this unwanted input affects the blue economy. The blue economy, which includes industries and research associated with marine and ocean resources, is often affected by marine pollution on multiple levels, such as economic costs, direct resource impacts, health risks, and infrastructure damage. In one report, the pollution-related issues in many countries were estimated at 9 t/inh and clean-up costs between $12 to $160/t. More extensive pollution mitigation projects might take up to 15 years to conclude and cost up to $500/t. To better understand the role of marine pollution and its impact on the blue economy, some key parameters are discussed as follows: the role of biofouling, volatile organic compounds, the impact of metals, anionic pollutants, and antifouling coatings. The review findings also highlight the impact of marine pollution on ecosystems and associated economic activities, which could be reduced through measures such as better international cooperation, waste management, and the development of sustainable practices. Related information on the strategies and policies that could be adopted for sustainable blue economy are stated after each section.Keywords：marine environment;blue economy;marine pollution;biocorrosion;biofilm13|17|0Updated：2025-08-07
- Abstract：Harmful algal blooms (HABs) of dinoflagellates pose significant threats to aquaculture, marine ecosystems, and human health. While resting cysts have been well known for their vital roles in initiating HABs of dinoflagellates, mapping results of the cyst abundance and distribution in marine sediments have been also well documented to be a highly valuable predictor, and thus can be used as a basis to assess the risk of HABs. We attempted to establish a framework for the risk assessment of dinoflagellate HABs based mainly on cyst-mapping of marine sediments and a case application of it to the risk assessment of HABs in the Yellow Sea. In the framework, firstly, the targeted marine area subjected to the assessment was determined and gridded into different assessment units according to their geography, administration, and ecological or economic function. Secondly, the dinoflagellate cyst abundance from the surface sediment, HABs records, and the monitoring results of vegetative cells for all or particular species of concern were collected experimentally or by literature search, as three main indicators scored and weighted respectively with different values. The scoring and weighting process was based on scientific reasoning and empirical consideration as detailed in the text. Thirdly, the risk of HABs occurrences for all or any particular species of concern at each site was ranked with five levels according to the calculated risk values. Finally, the final evaluation results were presented with tables, matrix diagrams, and color-coded textual annotations on nautical charts. As a case application, we performed a risk assessment for HABs of target species in the Yellow Sea, which warned high risks of HABs for Karlodinium veneficum, Gymnodinium catenatum, and others. This assessment framework provides a practical and testable tool for all involved stakeholders, and subject to improvement along with the advancement of ecology of HABs.Keywords：harmful algal bloom (HAB);dinoflagellate;resting cyst;risk assessment;cyst mapping;Yellow Sea11|15|0Updated：2025-08-07
- Abstract：Silicon limitation negatively affects the growth and metabolism of diatoms. However, its influence on the topography and mechanical properties of diatom frustules, and consequently on predation, remains unclear. We investigated how silicon limitation affects the mechanical strength of diatom frustules. Under silicon limitation, the growth rates of diatom Cylindrotheca closterium, Amphora coffeaeformis, Thalassiosira weissflogii, and Cyclotella sp. decreased by 19%, 56%, 42%, and 73%, respectively. Similarly, the biogenic silica content of silicon-limited C. closterium, T. weissflogii, and Cyclotella sp. decreased by 17%, 11%, and 9%, respectively, whereas A. coffeaeformis showed a 63% increase. Atomic force microscopy and X-ray photoelectron spectroscopy revealed that silicon shortage reduced frustule hardness by approximately 60% and decreased condensed silica components on their surface by about 80%, except in A. coffeaeformis. Additionally, copepods consumed 20% to 600% more diatoms grown under silicon deficiency compared to those grown under Si-rich conditions, with the exception of A. coffeaeformis. These findings suggest that silicon limitation diminishes diatom populations and accelerates carbon export from diatoms to the deep sea.Keywords：Si limitation;diatom;frustule;mechanical property;copepod6|8|0Updated：2025-08-07
- Abstract：As a frequently-observed phenomenon in the northern South China Sea (nSCS), subsurface chlorophyll maximum (SCM) evolution from summer to winter remains unclear, neither the associated hydrographic control. In this study, on the basis of in-situ data of fall-season cruises in 2004–2006, we characterized the depth, thickness and intensity of the SCM in the nSCS using a general Gaussian-function fitting approach, and investigated a linkage to the corresponding ocean vertical buoyance properties. Our results show that the SCM becomes deeper, thicker and less intense offshore-wards in the nSCS during fall seasons. In parallel, a correlation between the SCM variation and mixed layer depth exists in the nSCS, and it becomes pronounced in the shelf region compared to the slope and basin areas in autumn. Physically, once warmer surface ocean and thus stronger thermo-determined stratification, the SCM layer goes deeper and becomes thicker and less intense in the nSCS, especially in the shelf area of the nSCS. Moreover, the impact of water temperatures at deeper layers on the vertical stratification exerts more consequent roles on the spatial variability of SCM, compared to surface temperatures in the nSCS. Specifically, the isotherm line of 22 °C acts as crucial indicator for variations of the SCM in the nSCS during autumns.Keywords：subsurface chlorophyll maximum (SCM);northern South China Sea (NSCS);autumn season;hydrographic control12|4|0Updated：2025-08-07
- Abstract：The turbidity maximum zone (TMZ) is a distinctive aquatic environment marked by consistently higher turbidity compared to upstream and downstream section. In the TMZ, physicochemical properties such as intense light limitation, abundant nutrients, and rapid salinity shifts play a crucial role in shaping phytoplankton dynamics. The Qiantang River estuary-Hangzhou Bay (QRE-HZB) is a macrotidal estuary system known for its exceptionally high suspended solids concentration. To investigate the impact of TMZ on the standing crop and size structure of phytoplankton in the QRE-HZB, we conducted three cruises in dry, wet, and dry-to-wet transition seasons during 2022–2023, by assessing parameters including size-fractionated chlorophyll a (chl a), turbidity, Secchi depth, temperature, salinity, nutrients, and mesozooplankton. Results reveal significant variations in the TMZ and associated environmental factors in different periods, which markedly influenced the phytoplankton chl-a concentration, size structure, and cell activity (pheophytin/chl a). The chl-a concentration was high with micro-phytoplankton predominance in wet season, while nano-phytoplankton dominated in dry season. Within the TMZ, lower chl-a concentrations and pico-chl-a contributions, alongside higher pheophytin/chl-a and micro-chl-a contributions, were observed. The Spearman’s rank correlation and generalized additive model analyses indicated strong correlations of chl-a concentrations with turbidity, nutrients, and mesozooplankton. Redundancy analysis further revealed that salinity, nutrients, and turbidity significantly regulated variations in size structure. Phytoplankton mortality within the TMZ was primarily driven by high turbidity and salinity fluctuations, reflecting the vigorous resuspension and mixing of freshwater and seawater in the QRE-HZB. These findings highlight that the standing crop and size structure of phytoplankton were strongly regulated by the TMZ and associated physicochemical factors in the macrotidal QRE-HZB.Keywords：Qiantang River Estuary;Hangzhou Bay;turbidity maximum zone;phytoplankton;standing crop;size structure14|4|0Updated：2025-08-07
- Abstract：Ctenophore Pleurobrachia globosa (P. globosa) invades even the northernmost Bohai Sea from the south of China. Three years (2019–2021) of surveys were conducted in the Bohai Bay (BoB) of the Bohai Sea to examine its population dynamics and potential impact on nuclear power plants. Results show that P. globosa mainly occurred from July to October each year, reaching the maximum abundance in August/September and even bloomed in August 2020. Correlations with environmental factors indicate this species has strong tolerance to acidification and hypoxia, and it has potentially indirect feeding relationship with phytoplankton. Seven stages in three groups were illustrated in life history of P. globosa. Two entire generations were detected in August, confirming its 2-week generation time. Spawning time started earlier in the south than in the north of BoB. The spatiotemporal variation and life cycle of P. globosa in BoB are useful for further study on the invasion, bloom, aggregation, and regeneration of P. globosa.Keywords：Pleurobrachia globosa;population dynamic;spatiotemporal variation;life history;nuclear power plant;Bohai Bay10|4|0Updated：2025-08-07
Ecology
- Abstract：In our previous studies, we obtained scallops with black mantles by treating fertilized eggs with EMS (ethylmethane sulfonate) in the Argopecten scallop variety “Bohai”. While scallops that are potentially rich in melanin may have higher market values, the mechanisms underlying the occurrence of these black-mantled are largely unknown. We sequenced and compared the transcriptomes and metabolomes of the mantles from the black-mantled “Bohai Red” scallops and those from the scallops with normal-colored (white) mantles. Results reveal that the pigment component in the black mantle of scallops was melanin indeed. Based on the transcriptome data, 1 314 differentially expressed genes were obtained and subjected to the gene ontology (GO) enrichment analysis. The upregulated genes in the black mantle were mainly enriched in transition metal ion binding, hydrolytic enzyme activity, and copper ion binding. Several candidate genes associated with black mantle formation in scallops were identified. Among them, the downregulation of monoamine oxidase (MAO) and glutathione S-transferases (GST) genes and upregulation of cytochrome P450 family 3 subfamily A (CYP3A) and protein kinase A (PKA) genes may have a positive effect on the formation of black mantle in scallops. The differentially expressed metabolites were mainly enriched in metabolism-related biological pathways, suggesting that the formation of black mantle in scallops may affect physiological functions related to metabolism in scallops. This study provided new evidence for understanding the mechanisms of coloration in scallop tissues, which eventually benefit the selection of new scallop strain with high melanin content.Keywords："Bohai Red" scallop;melanin;transcriptome analysis;metabolomic analysis;enzyme‐linked immunosorbent assay6|4|0Updated：2025-08-07
- Abstract：Endoplasmic reticulum (ER) homeostasis is vital to cell physiological functions. Glucose-regulated protein 78 (GRP78) is a molecular chaperone considered a sensor of ER stress and participates in maintaining ER homeostasis. However, very few studies have provided detailed descriptions of crustacean GRP78 genes. The complete coding sequence of the GRP78 of Neocaridina denticulata sinensis was obtained and termed NdGRP78 in this study. Sequence analysis showed that the open reading frame of NdGRP78 encodes a protein of 656 amino acid residues, and the encoded protein includes three heat shock proteins 70 (HSP70) family conservational motifs, one ATP/GTP binding site A, and one ER homolog region. Multiple sequence alignments demonstrated that the sequences of these key protein functional domains were highly conserved. Phylogenetic analysis revealed that the NdGRP78 protein belongs to a member of the HSP70 family. The NdGRP78 mRNA was detected in all tested tissues by real-time fluorescence quantitative PCR (qPCR), suggesting that the NdGRP78 mRNA was the constituent expression in N. denticulata sinensis. The in-situ hybridization result showed that the expression of NdGRP78 mRNA occurred in all types of hepatopancreas cells. Furthermore, the NdGRP78 expression was significantly increased when shrimp were transferred into Vibrio parahaemolyticus-EGFP infected conditions, low or high temperature, and hypoxia. The above results indicate that NdGRP78 expressions were associated with stress responses. This study provided a theoretical support to the good understanding of the role of NdGRP78 in response to different types of environmental stress tolerance.Keywords：Neocaridina denticulata sinensis;GRP78;in-situ hybridization;environmental stress6|1|0Updated：2025-08-07
- Abstract：As a key component of the plant antioxidant enzymatic system, superoxide dismutase (SOD) can efficiently protect cells from oxidative stress and maintain redox homeostasis. Currently, there are few studies related to SOD genes in various taxa of algae, and the specific functions and evolutionary patterns of these family members remain unclear. In this study, comprehensively evolutionary analysis of SOD gene family in the bladed Bangiales was carried out. A total of 9, 10, and 12 SOD genes were identified from three species of Pophyra umbilicalis, Pyropia haitanensis, and Pyropia yezoensis, respectively. Based on phylogenetic analysis, SOD gene members within the same subfamily exhibited similar motif patterns as well as conserved domains, which could be attribute to Cu/Zn-SOD and Fe/Mn-SOD. The promoter regions of SOD genes were rich in hormone-responsive, stress-responsive, and growth cis-acting elements, with variations and similarities observed among different species of other red algae and subfamilies. According to subcellular location prediction, it is suggested that Cu/Zn-SOD was predominantly located in chloroplasts, while Fe/Mn-SOD was primarily located in mitochondria. Also, the two subfamilies differed significantly in the two-/three-dimensional protein structures. In terms of gene evolution, the strongest collinearity relationship was shown between Pyropia haitanensis and Pyropia yezoensis, with all the 1꞉1 orthologous gene pair being subjected to a purifying selection (Ka/Ks<1, Ka: non-synonymy rate; Ks: synonymy rate). Moreover, 12 SOD genes underwent positive selection during the evolutionary process. Furthermore, gene expression analysis based on transcriptomic data from Pyropia haitanensis showed that the expression patterns of SOD genes varied under different stress conditions. Together, this study revealed the evolutionary pattern of SOD genes in three bladed Bangiales species , which will lay the foundation for subsequent studies on the function of SOD genes.Keywords：superoxide dismutase;bladed Bangiales;gene family;evolutionary analysis6|8|0Updated：2025-08-07
- Abstract：This study explored the morphological characteristics and differences of the otoliths in three native species, Schizothorax biddulphi, S. eurystomus and S. curvifrons, in the Yarkand River of the Tarim River, Xinjiang, China. A total of 93 specimens (27 S. biddulphi, 39 S. eurystomus, and 27 S. curvifrons) were analyzed using six basic otolith morphological parameters (OA, Rmax, Rmin, OP, OL, OW) to derive six factors (F1, F2, F3, F4, F5, F6) and seven indices (RO, FF, CI, RE, EL, RR, AR) for morphological assessment. A discriminant analysis incorporating 77 Fourier coefficients of the otoliths revealed distinct morphological differences among the species. A significant power function relationship between otolith morphology and standard length was observed across the species, with R2 values ranging from 0.409 to 0.749. Principal component analysis (PCA) of 7 traditional otolith morphological indicators explained 81.243% of the variance, yielding an overall species discrimination rate of 81.65%. Further PCA of 77 Fourier harmonic values enhanced the discrimination accuracy, with the first 3 components accounting for 77.49% of the total variation and an improved discrimination rate of 100.00%. Cluster analysis resulted in the grouping of S. biddulphi and S. curvifrons together and revealed their association with S. eurystomus, indicating notable morphological distinctions. Both otolith shape indices and elliptical Fourier analysis have been useful in distinguishing the phenotypic units of different fish species. In this study, otolith morphology was applied for the first time to identify Schizothorax species, providing an in-depth description of species distribution and evolutionary history. This study provides a reference for the identification and systematic classification of Schizothorax species and a scientific basis for formulating effective species protection measures, for promoting the sustainable management of species and important habitats.Keywords：Schizothorax;otolith morphological analysis;elliptic Fourier transform;species discrimination11|8|0Updated：2025-08-07
- Abstract：During the expedition to an unnamed seamount of Caroline Ridge in the northwest Pacific Ocean, one Thalassometra specimen was sampled, and careful morphological assessment suggested that this specimen represents a new species within the genus Thalassometra: Thalassometra brachia sp. nov. This new species was collected at a depth of 688 m and is characterized by the dome-like centrodorsal, large number of arms (43 in total), irregularly arranged sockets with three per radial area, P2 and P3, similar in size and character and smaller than P1, spinous median carination on the first and second ossicles of the division series and on the first two brachials, and dense spicules in brachial bases.Keywords：new species;Crinoidea;Thalassometra;seamount;Western Pacific7|1|0Updated：2025-08-07
- Abstract：Two new species of superfamily Sphaerolaimoidea: Sphaerolaimus obesus sp. nov. and Pseudosteineria articulata sp. nov. are described from the Yellow Sea. Sphaerolaimus obesus sp. nov. is characterized by body stout, cuticle finely striated with lateral alae, outer labial sensilla and cephalic sensilla papilliform, eight bunches of subcephalic setae different in length, amphidial fovea situated at the level of buccal cavity, spicules arcuated with proximal end cephalated, gubernaculum with dorsal-caudal directed apophysis different in shape, seven precloacal papilliform supplements, tail conico-cylindrical with three terminal setae. Pseudosteineria articulata sp. nov. is characterized by cuticle distinctly annulated with lateral alae, six outer labial setae jointed, eight rows of subcephalic setae present, two rows of long somatic setae scattered along lateral alae, amphidial fovea posterior to subcephalic setae, spicules curved and jointed with proximal end with large manubrium, gubernaculum slightly funnel-shaped, tail conico-cylindrical. Phylogenetic analysis based on combined rDNA sequences place Sphaerolaimus obesus sp. nov. and Pseudosteineria articulata sp. nov. within family Sphaerolaimidae and Xyalidae, respectively. Relationships analysis within the superfamily Sphaerolaimoidea shows Sphaerolaimidae as a sister clade to Xyalidae and genera of Xyalidae as paraphyletic clades.Keywords：free living nematode;taxonomy;small subunit (SSU);large subunit (LSU)8|10|0Updated：2025-08-07
- Abstract：Chaetoceros is a species-diverse genus of marine diatoms. The section Chaetoceros, recognized for the presence of numerous chloroplasts in both cell body and setae, is a common group of marine phytoplankton containing some species, which may cause harm to marine organisms due to the robust setae. Modern taxonomic studies combining morphological and molecular data are still limited for the section Chaetoceros. To explore the diversity of the section Chaetoceros, monoclonal strains were established from the South China Sea and two novel species are described here, C. tetracarina sp. nov. and C. dicrinis sp. nov. Chaetoceros tetracarina is unique by the rimoportula on the anterior valve having four basal ridges supporting the external tube, whereas the other rimoportulae in the same chains or the one on the posterior valve for single cells each only possess a long external tube and lack basal ridges. Chaetoceros dicrinis is solitary and characterized by the symmetrical extending of the two setae on the same valve under light microscope (LM). The phylogenetic results show the presence of several groups within the section Chaetoceros. Chaetoceros tetracarina was sister to C. cf. pseudodichaeta, but differed by 33 and 46 bps in ribosomal large-subunit (LSU) and small-subunit (SSU) sequences respectively. The most closely-related species of C. dicrinis was C. denticulatus, but they were distinctly different morphologically, differing by 3 and 2 bps in LSU and SSU sequences respectively. This study provides new findings to understand the diversity of section Chaetoceros; however the inner relationships within this section remain largely unresolved.Keywords：Chaetoceros tetracarina;Chaetoceros dicrinis;new species;ribosomal rDNA;rimoportula10|1|0Updated：2025-08-07
Biology
- Abstract：Inland culture of shrimp integrated with irrigation could be one of the most feasible livelihood options for many households nearby saline land. Compared with seawater and most of reported brackish water used for shrimp culture, the sulfate content was higher in both surface and ground water in the central Asia. We evaluated the effects of salinity, the SO2-4 /Cl- ratio and their interaction on the growth, oxygen consumption, Na+/K+-ATPase activity, total antioxidant capacity (T-AOC), and hepatopancreas histology of Litopenaeus vannamei reared in artificial seawater. The experiment lasted for 30 d, two salinity levels (20 and 10) and four SO2-4 /Cl- ratios (0.14, 0.577, 1.127, and 2.225 mg/mg) of waters were set. Results show no significant differences in survival among groups. Salinity and its interaction effects with SO2-4 /Cl- ratio did not significantly affect the final body weight, weight gain, and specific growth rate of shrimps, whereas the SO2-4 /Cl- ratio did (P<0.05). Shrimp mean weight gain and specific growth rate at water SO2-4 /Cl- ratio of 2.225 were significantly lower than at ratio of 0.14. At salinity 20, the shrimp final body weight at water SO2-4 /Cl- ratio of 2.225 was significantly lower than at other ratios (P<0.05), whereas there was no significant difference in final body weight among treatments at salinity 10 (P>0.05). Oxygen consumption, Na+/K+-ATPase activity, and T-AOC increased with increasing SO2-4 /Cl- ratio at both salinities. L. vannamei exposed to water SO2-4 /Cl- ratio of 2.225 at salinity 20 showed severe histopathological changes. This study indicated that L. vannamei has strong tolerance to sulfate in brackish water environment. The shrimp is more adaptable to SO2-4 /Cl- ratios below 2.225 at lower salinity, and the optimal SO2-4 /Cl- range for the growth is 0.14–0.577 (mg/mg) regardless of salinity level.Keywords：salinity;SO2-4 /Cl- ratio;interaction;Litopenaeus vannamei;growth;hepatopancreas6|12|0Updated：2025-08-07
- Abstract：As an economically crucial species in the southeast Pacific Ocean, understanding the spatiotemporal distribution changes of the habitat of Trachurus murphyi under the influence of climate change is essential for effective resource assessment and management. The spatiotemporal changes in suitable habitats of T. murphyi under three climate change scenarios (SSP126, SSP370, and SSP585) of Phase 6 of the Coupled Model Intercomparison Project (CMIP6) were explored based on key environmental factors affecting the potential distribution of the species in a habitat suitability index (HSI) model. Results show that seawater temperature would increase under different scenarios, while the mixed layer depths would decrease under SSP370 and SSP585 scenarios but vary slightly under the SSP126 scenario, which is similar to the variation in different climate periods. The positive difference in seawater temperature will be distributed in the central, southern, and offshore regions of Chile, and the negative difference in mixed layer depths be accounted for a large region. Under different climate scenarios, the HSI value for fishing ground and the overall proportion of suitable habitat area of T. murphyi will be decreased over the forecasted period. The suitable habitat of T. murphyi is concentrated in the 42°S–47°S area and will move to the southwest in different climate periods. Based on short-term climate change, the proportion of suitable habitat areas in the high seas of Chile is larger than in the exclusive economic zone under medium- and long-term climate change under different scenarios. The results of the gravity center of suitable T. murphyi habitat indicates that the spatial distribution of T. murphyi might be related to variations in oceanic currents. These findings provide insights for the effective fisheries resource management of T. murphyi in the Southeast Pacific Ocean.Keywords：southeastern Pacific Ocean;Chilean jack mackerel;environment variation;climate change;habitat change;spatio-temporal variation8|3|0Updated：2025-08-07
Aquaculture and Fisheries
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