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Volume 42 ， Issue 5 ， 2024
- Abstract：Geophysical fluid dynamics (GFD) is an interdisciplinary field that studies the large-scale motion of fluids in the natural world. With a wide range of applications such as weather forecasts and climate prediction, GFD employs various research approaches including in-situ observations, satellite measurements, numerical simulations, theoretical analysis, artificial intelligence, and physical model experiments in laboratory. Among these approaches, rotating tank experiments provide a valuable tool for simulating naturally-occurring fluid motions in laboratories. With proportional scaling and proper techniques, scientists can reproduce multi-scale physical processes of stratified fluids in the rotation system, which allows for the simulation of essential characteristics of fluid motions in the atmosphere and oceans. In this review, rotating tanks of various scales in the world are introduced, as these tanks have been actively used to explore fundamental scientific questions in ocean and atmosphere dynamics. To illustrate the GFD experiments, three representative cases are presented to demonstrate the frontier achievements in the the GFD study by using rotating tank experiments: mesoscale eddies in the ocean, convection processes, and plume dynamics. Detailed references for the experimental procedures are provided. Future studies are encouraged to further explore the utilization of rotating tanks with improvements in experimental design and integration of other research methods. This is a promising direction of GFD to help enhance our understanding of the complex nature of fluid motions in the natural world and to address the challenges posed by global environmental changes.Keywords：laboratory experiment;rotating tank;geophysical fluid dynamics (GFD)28|18|0Updated：2024-11-19
- Abstract：The Antarctic Bottom Water formation site Vincennes Bay, East Antarctica is experiencing a substantial intrusion of modified Circumpolar Deep Water (mCDW), which may inhibit the formation of Dense Shelf Water (DSW) and drive basal melting of the ice shelves. Based on hydrographic data obtained from March to November in 2012, we evaluated the spatial spread of mCDW over the continental shelf region of Vincennes Bay and the associated temporal evolution of water properties, as well as the sea ice formation effect on water column in the coastal polynya. Results show that two branches of mCDW occupied the deep layers of the continental shelf, distinguished by the potential density (smaller than 27.8 kg/m3 or not) when potential temperature θ=0.5 °C in the θ-salinity space. The warmer and less dense branch observed on the east plateau, accessed the eastern ice shelves in the coastal polynya to drive basal melting of ice shelves. In contrast, the other colder and denser branch in the mid-depression reached the western Underwood Ice Shelf. DSW formation was detectable in the coastal polynya during September–November, proving the occurrence of deep convection. Surface heat loss and brine rejection during the intensive sea ice formation contributed to the destratification of the water column in the coastal polynya. It was estimated that at least 1.11±0.79 TW heat carried by mCDW into the inner part of the polynya.Keywords：modified circumpolar deep water;evolution of water properties;coastal polynya;ice shelf;Vincennes Bay28|22|0Updated：2024-11-19
- Abstract：Based on an algebraically Rossby solitary waves evolution model, namely an extended (2+1)-dimensional Boussinesq equation, we firstly introduced a special transformation and utilized the Hirota method, which enable us to obtain multi-complexiton solutions and explore the interaction among the solutions. These wave functions are then employed to infer the influence of background flow on the propagation of Rossby waves, as well as the characteristics of propagation in multi-wave running processes. Additionally, we generated stereogram drawings and projection figures to visually represent these solutions. The dynamical behavior of these solutions is thoroughly examined through analytical and graphical analyses. Furthermore, we investigated the influence of the generalized beta effect and the Coriolis parameter on the evolution of Rossby waves.Keywords：Rossby wave;Boussinesq equation;Complexiton solution;Breather solution26|20|0Updated：2024-11-19
- Abstract：Tropical cyclones constitute a major risk for coastal communities. To assess their damage potential, accurate predictions of their intensification are needed, which requires a detailed understanding of the evolution of turbulent heat flux (THF). By combining multiple buoy observations along the south-north storm track, we investigated the THF anomalies associated with tropical storm Danas (2019) in the East China Sea (ECS) during its complete life cycle from the intensification stage to the mature stage and finally to its dissipation on land. The storm passage is characterized by strong winds of 10–20 m/s and a sea level pressure below 1 000 hPa, resulting in a substantial enhancement of THF. Latent heat (LH) fluxes are most strongly affected by wind speed, with a gradually increasing contribution of humidity along the trajectory. The relative contributions of wind speed and temperature anomalies to sensible heat (SH) depend on the stability of the boundary layer. Under stable conditions, SH variations are driven by wind speed, while under near-neutral conditions, SH variations are driven by temperature. A comparison of the observed THF and associated variables with outputs from the ERA5 and MERRA2 reanalysis products reveals that the reanalysis products can reproduce the basic evolution and composition of the observed THF. However, under extreme weather conditions, temperature and humidity variations are poorly captured by ERA5 and MERRA2, leading to large LH and SH errors. The differences in the observed and reproduced LH and SH during the passage of Danas amount to 26.1 and 6.6 W/m2 for ERA5, respectively, and to 39.4 and 12.5 W/m2 for MERRA2, respectively. These results demonstrate the need to improve the representation of tropical cyclones in reanalysis products to better predict their intensification process and reduce their damage.Keywords：tropical cyclone (TC);air-sea turbulent heat flux (THF);latent heat flux;sensible heat flux;buoy observation;reanalysis product19|25|0Updated：2024-11-19
Physics
- Abstract：Tephra layers in the western Philippine Sea, characterized by abundant volcanic glass shards, may provide crucial evidence on the eruption history of volcanoes and tectonic evolution of the western Pacific. A 220-ka sediment core from the Benham Rise in the western Philippine Sea offers new insights into the provenance of four intercalated tephra layers (T1–T4, in chronological order) containing either colorless or brown glass shards. Relative to primitive mantle, all glass shards are enriched in large-ion lithophile elements, such as Rb, Cs, and Pb, and depleted in high field-strength elements, such as Th, Nb, and Ta, indicating a subduction-related origin. The colorless glass shards are characterized by high SiO2 (>78%) and light rare earth element (LREE) contents as well as high La/Sm ratios (>9), low FeO and MgO contents (<1%), low Sr/Y (<15) and high Ba/Th ratios (>100), pointing to a rhyolitic composition and a medium-K calc-alkaline serial affinity. In contrast, the brown glass shards are characterized by lower SiO2 (<63%) and LREE contents, higher FeO, MgO, and CaO contents, lower La/Sm (<6) and Ba/Th (<75), and similar Sr/Y ratios (<15), indicating derivation from medium to high-K calc-alkaline andesite magma. Brown glass shards from layers T3 (152 ka) and T4 (172 ka) were correlated with volcanic deposits from the Taal and Laguna Caldera in the Maccolod Corridor, respectively, while the colorless glass shards from layers T1 (36.5 ka) and T2 (61.2 ka) were likely sourced from the Irosin Caldera in the Bicol Arc. Establishing the provenance of late Pleistocene tephra layers in the western Philippine Sea is helpful to complement a Philippine volcanic history and establish a regional tephro-chronostratigraphy.Keywords：volcanic glass;provenance;chemical composition;Philippine Sea;late Pleistocene14|28|0Updated：2024-11-19
- Abstract：Situated between the petroliferous Cenozoic Zhujiang (Pearl) River Mouth Basin and the mud volcano-rich Mesozoic Dongsha Basin in the middle sector of the northern South China Sea, the Weitan Banks area has been previously mapped as a basement high that is composed of Mesozoic magmatic rocks. In this study, we present several favorable indicators for petroleum geology that were detected from geophysical profiling and benthic sampling in the area. A conspicuous hill was discovered, named “Zhongwei Hill”, ~80 m high above the ~340 m deep seafloor and ~1 km broad, in a depression with more than 7 km thick sedimentary strata. The Zhongwei Hill was seismically imaged with a mushroom-shaped structure and containing a cake-like crown, fluid flow pipes, and an ~10 km broad anticline at depth. Thus, the hill represents a source-plumbing-eruption system. Shallow gas zones linked to deep fracture were found at or near the hill. Stratigraphic correlation indicates that the deep strata comprise the Jurassic and Paleogene strata, the major hosts of hydrocarbon source rocks. In addition to the hill, there are number of mounds from which three bottom water samples were collected and the samples are rich in dissolved methane with concentrations high up to ~900 nmol/L, much higher than the background level (0.5–2 nmol/L). The benthic samples are rich in coarse sediment clastics, authigenic carbonate nodules, and deep-water habitats likely feeding on methanotrophic community. Given these observations and the context, we propose that the Zhongwei Hill represents a mud volcano, likely thermally driven, that seeps methane from Jurassic and Paleogene source layers, thus poses a favorable clue for significant hydrocarbon generation capacity in transitional zone of the Zhujiang River Mouth Basin and the Dongsha Basin.Keywords：South China Sea;Zhongwei Hill;deep-level anticline;mud volcano;Mesozoic source layer;hydrocarbon generation11|19|0Updated：2024-11-19
- Abstract：Six hydrothermal sediment samples were collected from the Xunmei and Tongguan hydrothermal fields along the southern Mid-Atlantic Ridge during the China Ocean Cruise DY46 in 2017. Sulfides and oxides in the samples were separated, and Cu and Zn isotope compositions were analyzed. Results show that the ranges of δ65Cu values of the bulk sediments, sulfides, and oxides were 0.36‰–2.46‰, 0.21‰–1.10‰, and 0.68‰–1.52‰, respectively. The δ65Cu values of sulfides in four samples (46II-14, 46II-30, 46III-06, and 46II-09) were relatively low (0.21‰–0.50‰), corresponding to the δ65Cu values of sulfides from inactive old hydrothermal chimneys in northern Mid-Atlantic Ridge (nMAR), suggesting that the sulfides in the sediments were originated from collapsed dead chimney mainly. While the δ65Cu values of the other two samples (46III-02 and 46III-08) were relatively high (1.10‰–0.96‰), corresponding to the δ65Cu values for active hydrothermal chimneys sulfides in nMAR, which indicated that the sulfides in these two samples might mainly come from sulfide particles settled from active hydrothermal plume. Because of the high density of sulfide particles, they tended to settle near the hydrothermal vents first. Therefore, high δ65Cu values of sulfides in 46III-02 and 46III-08 implied that undiscovered active hydrothermal vents near the sampling positions of 46III-02 in the Xunmei hydrothermal field and 46III-08 in the Tongguan hydrothermal field. The δ66Zn values of hydrothermal sediments and sulfides ranged 0.11‰–0.43‰ and 0.29‰–0.67‰, respectively. In the four samples from the Xunmei hydrothermal field, a positive correlation was found between the distance of the sampling position from sulfide mineralized spot and the Zn isotopic ratio, showing that the greater the distance from the mineralized spot, the heavier the Zn isotope composition as seen in two samples (46II-30 and 46II-14) of the Xunmei-3 spot. This result aligned with the findings of Wilkinson et al. (2005) and Baumgartner et al. (2023), suggesting that the lower the Zn isotope composition, the closer it is to the hydrothermal vent. However, in the Xunmei hydrothermal field, the Zn isotope composition in the other two samples (46III-02 and 46III-06) showed the opposite trend. This indicated that there might be an active hydrothermal vent near the sampling location of sample 46III-02. This observation aligned with the Cu isotope analysis results. This study showed that Cu-Zn isotopes are good indicators for understanding the formation mechanisms of hydrothermal sediments and for locating active hydrothermal vents.Keywords：Cu-Zn isotope;hydrothermal sediments;mineral exploration;southern Mid-Atlantic Ridge11|17|0Updated：2024-11-19
- Abstract：To understand the acoustic and physical properties of piston core samples collected from the Sunda continental shelf and analyze their distribution patterns, the samples were analyzed in laboratory, from which three provinces were divided in sound speed, sound speed ratio, porosity, wet bulk density, and maximum shear strength. Province Ⅰ had lower sound speed and sound speed ratio (<1.04), high porosity, and low wet bulk density. Province Ⅱ had higher sound speed and sound speed ratio (>1.04), low porosity, and high wet bulk density. Province Ⅲ had the lowest sound speed and sound speed ratio (0.99), highest porosity (81%), and lowest wet bulk density (1.34 g/cm3). The distribution pattern indicates that sediment movement, sediment source, topography, and hydrodynamic conditions influenced the distribution of acoustic and physical properties. Furthermore, we investigated the relationship of the maximum shear strength to the porosity and wet bulk density, and found that the maximum shear strength was proportional to both the porosity and wet bulk density. This finding has significant implications for ocean engineering applications.Keywords：seafloor sediment;acoustic property;Sunda Shelf11|14|0Updated：2024-11-19
- Abstract：A total of 98 samples from two boreholes in shallow sea area and two oyster reefs in adjacent coastal plain in the northwestern coast of Bohai Bay were collected for diatom analyses and species identification. The ratio of the marine species Thalassionema nitzschioides to the intertidal-coastal species complex Cyclotella striata/stylorum serves as a novel proxy for assessing the strength of marine influence. Chronological data, corrected for the local residence time effect, facilitated the construction of a diatom proxy-based marine influence curve for the study area. This curve delineates the dynamics of marine influence and their correlations with paleo-climate fluctuations and the East Asian monsoon variability, as well as their role in chenier formation. Results include: (1) eight periods of intensified marine influence have been documented since 7 000 a BP in the study area. The peak of each period, as determined by the diatom proxy, corresponds closely to the warm climatic phases and stronger East Asian summer monsoons, suggesting that the peaks marine influence indicate typically the periods of climatic warmth and monsoon activity intensification in the region; (2) a strong correlation exists between the development of cheniers and marine influence, and chenier formation began with the increasing marine influence and terminated at the end of warm periods as marine influence weakens. The climatic changes in the coastal area, as indicated by the diatom proxy, hold significant potential for future related research endeavors.Keywords：Bohai Bay;diatom;diatom-based marine influence curve;paleo-climate;Holocene11|13|0Updated：2024-11-19
Geology
- Abstract：Water scarcity and pollution pose a threat to the sustainable development of cities and society. Therefore, it is crucial to analyze the hydrochemical characteristics and carbon dynamics of water-deficient areas. Taking the Taiyuan section of Fenhe River as the research object, we systematically explored the hydrochemical characteristics of surface water and its evolutionary processes, as well as the ecological effect of algal carbonic anhydrase in carbon cycle using the hydrochemical evolution method and correlation analysis. The ternary diagram demonstrates that the main water chemical type in Fenhe River was SO2-4 ·Cl--Na+. The Gibbs and end-member diagrams of each ion display that the chemical composition of surface water was mainly controlled by silicate decomposition. The chemical ions originated mainly from dissolution of some minerals, such as plagioclase, halite, dolomite, calcite, and gypsum. The diatoms had a lower CO2 requirement because they exhibited a higher abundance at a lower partial pressure of CO2 (pCO2). However, high CO2 concentration had a positive effect on cyanobacteria, which reduced the active transport of HCO3-, saved the energy needed for this part of active transport, and indirectly improved the overall photosynthetic efficiency of algae. Carbonic anhydrase (CA) activity was significantly negatively correlated with pCO2 and positively correlated with HCO3- concentration, indicating that CA in water promoted the conversion of CO2 to HCO3-. The HCO3- generated from this process continued to participate in the erosion of silicate rocks, sequestering CO2 in the form of CaCO3, which has a non-negligible impact on the carbon sink in the Fenhe River. These consequences may have important implications for the biogeochemical cycling occurring in urban water.Keywords：hydrochemistry;inorganic carbon;phytoplankton community;carbonic anhydrase;Fenhe River24|17|0Updated：2024-11-19
- Abstract：Microeukaryotes play a vital role in shaping marine ecosystems, especially in marine productivity, the microbial food web, and carbon cycle. The Indian Ocean is one of the largest oligotrophic areas in the world, but little is known about the biodiversity of microeukaryotes in the area. The community composition and geographical distribution of microeukaryotes collected from the surface (SUR) and deep chlorophyll maximum (DCM) layers in the southwestern Indian Ocean were studied using high-throughput sequencing of the 18S rRNA gene. The metagenomic data helped quantify the impact of environmental factors on microeukaryotic communities. The relative abundance of different taxa groups exhibited distinct patterns between SUR and DCM layers, except for the most dominant Dinoflagellata that accounted for more than 40.6% abundance in each sample. Radiolaria was much more abundant in the nutrient-rich DCM layer than the SUR layer. The community similarity of microeukaryotes decreased with increasing of geographic distance, whereas the temperature and inorganic nitrogen were the most important environmental parameters to community structure. Abundant communities were more influenced by dispersal limitations and rare communities were more responsive to environmental factors. Correlation network analyses revealed strong biotic interactions indicative of parasitism, predation and competition, and their contribution to microeukaryotic population in diverse environments. Overall, this study provided insights into the biodiversity of microeukaryotes by characterizing the differences between water layers and identifying the driving factors in the ocean.Keywords：microeukaryote;southwestern Indian Ocean;community structure;environmental factor;biotic interaction;Dinoflagellata16|9|0Updated：2024-11-19
- Abstract：Meroplankton play a crucial role in both benthic and pelagic ecosystems. Existing quantitative research on estimating the quantities of meroplankton groups is both underrepresented and inaccurate. To investigate and evaluate the influence of varying mesh sizes (505 and 160 μm) on the sampling efficiency of meroplankton, we conducted an examination using two commonly used plankton nets during the spring season in the Southern Yellow Sea (SYS). Our study revealed a total of 12 meroplankton groups, with 9 groups identified in the 505-μm mesh nets and 11 groups in the 160-μm mesh nets. The results demonstrated the superior collection efficiency of the 160-μm net compared to the 505-μm net across the majority of meroplankton groups. Furthermore, we focused on exploring the abundance, distribution patterns, and realized niches of meroplankton collected by the two mesh size nets, and observed that the distribution of meroplankton closely resembled the distribution of possible benthic adults in the SYS. Correlation analysis of the six dominant groups collected in the 160-μm mesh nets revealed that seawater temperature and salinity emerged as the key environmental factors driving variations in meroplankton abundance within the SYS. This study also found that a smaller mesh size net does not necessarily capture meroplankton more comprehensively. A comprehensive understanding of the ecological characteristics of meroplankton requires the combination of two types of nets for research. Our research significantly advances our understanding of the quantification, abundance, and distribution of meroplankton, serving as a valuable contribution to the broader landscape of detailed quantitative meroplankton studies.Keywords：meroplankton;plankton net mesh size;collection efficiency;distribution characteristic;realized niches11|2|0Updated：2024-11-19
- Abstract：Eddies are major elements of ocean dynamics that affect ocean production. Understanding their effects on plankton distribution may help understand the dynamics of harmful phytoplankton blooms. Previous studies on the effects of eddies in the northern Arabian Sea have primarily focused on the zooplankton community, and few have observed zooplankton dynamics during winter blooms of Noctiluca scintillans. We investigated zooplankton community structure and the related environmental variability during a N. scintillans bloom that was affected by an eddy in February 2018. The sampling stations were deployed at eddy core and eddy edge distinguished in salinity, temperature, and velocity. Results show that N. scintillans bloomed at the eddy core with high-velocity currents induced by warm eddies that moved from eddy core to eddy edge. As a result, blooms significantly changed the zooplankton community structure. Non-bloom stations had higher zooplankton diversity than bloom stations. Zooplankton at non-bloom stations were dominated by either tunicates or copepods, such as Thalia democratica and Pleuromamma gracilis. In addition to the influence of N. scintillans blooms, the velocity of eddy currents was a crucial factor on the similarities in the zooplankton community composition between eddy edge and eddy core. Moreover, the lower abiotic factors in bloom area contribute to the structuring of the zooplankton community during N. scintillans blooms.Keywords：eddy;zooplankton community;Noctilucascintillans;northern Arabian Sea9|7|0Updated：2024-11-19
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Epiphytic zooplankton community profiles in a typical urban wetland as revealed by DNA metabarcoding
Abstract：Zooplankton, a crucial component of urban wetland, are one of the effective bioindicators for monitoring the feeding stocks of organisms at higher trophic levels and assessing the ecological quality of ecosystems. However, information about the characteristics of epiphytic zooplankton community structure resulted from traditional methods is limited and hindered by the large amount of detritus and sludge attached to the macrophytes. We investigated the epiphytic zooplankton communities associated with macrophytes (Vallisneria, Nymphaea, and Thalia dealbata) in a subtropical wetland using as DNA markers of the 18S rRNA gene and the mitochondrial cytochrome c oxidase subunit I (COI) gene. A total of 241 OTUs of zooplankton were obtained from COI amplicons, including 194 OTUs of Rotifera, 22 of Cladocera, and 25 of Copepoda, while only 62 OTUs of zooplankton were obtained from 18S rDNA amplicons including 34 OTUs of Rotifera and 28 of Copepoda. The zooplankton communities associated with the three macrophytes were similar, but they differed significantly from those in the open waters. However, there were no significant temporal differences among the zooplankton communities. Epiphytic zooplankton communities were dominated by littoral zooplankton such as Testudinella, Lecane, and Philodina. Microzooplankton, especially littoral species, utilize macrophytes as food sources and as refuges against predation. This further led to an increase in α and β diversity of zooplankton communities in urban wetlands. Our result suggests that the joint use of multiple molecular markers could improve the taxonomic resolution and generate a comprehensive biodiversity profile of zooplankton.Keywords：environmental DNA;metabarcoding;diversity;macrophyte;cytochrome C oxidase subunit I (COI);18S rRNA18|4|0Updated：2024-11-19 - Abstract：Global warming has caused an increase in the frequency and duration of droughts worldwide. Droughts could trigger large changes in physico-chemical conditions and phytoplankton community in waterbodies, resulting in a shift in the phytoplankton community. Spring diatom blooms in reservoirs have been increasingly observed in the past decade in the Taihu Lake basin. The aim of the present study is to elucidate the impacts of droughts on aquatic environment and to determine the driving factors for the succession of the phytoplankton functional groups based on the analysis of data collected during spring from 2009 to 2020 in the Daxi Reservoir. The unimodal relationship between 1-month aggregated precipitation index and phytoplankton species richness indicated the competitive exclusion occurred in extremely drought period. The structural equation modeling indicated that drought-related low water level conditions intensified sediment resuspension, and increased the phosphorus-enriched nonalgal turbidity in the Daxi Reservoir. Concurrently, a steady shift in the Reynolds phytoplankton functional groups from L0, TD, J, X2, and A (phytoplankton taxa preferring low turbidity and nutrient conditions) to TB (pennate diatoms being adapt to turbid and nutrient-rich conditions) was observed. The increased TP and non-algal turbidity in addition to the lowered disturbance contribute to the prevalence of Group TB. Considering the difficulties in nutrient control, timely water replenishment is often a feasible method of controlling the dominance of harmful algae for reservoir management. Finally, alternative water sources are in high demand for ensuring ecological safety and water availability when dealing with drought.Keywords：drought;reservoir;sediments resuspension;phytoplankton functional group;diatom13|6|0Updated：2024-11-19
- Abstract：Environmental DNA (eDNA) has been used as an important tool for fish diversity analysis, which can greatly solve the problems in traditional survey methodology. However, little work has been done on the actual monitoring accuracy of eDNA. In this study, we analyzed the current status of fish resources in Erhai Lake in Yunnan, SW China, by dividing the lake into three sectors according to habitat differences, and compared the results of eDNA and traditional capture methods to investigate the shortcomings of the current analysis of eDNA results. A total of 27 fish species were detected by eDNA and traditional capture methods, including 20 and 19 fish species, respectively, and additional differences in fish composition between the two methods. The alpha diversity showed higher fish abundance and lower fish diversity by eDNA method compared to the traditional capture method, demonstrating that eDNA was not superior for use in fish diversity analysis. Fish community similarity analysis showed that community differences were generally significant for eDNA (P<0.05). RDA analysis indicated that environmental factors did not significantly affect fish communities monitored by the eDNA method. However, water temperature, aquatic plants, and water depth had significant (P<0.05) effects on fish communities in the traditional capture method, suggesting that eDNA results are insensitive to the effects of environmental factors. Our results illustrate the effectiveness of eDNA in fish identification and the issues in quantification compared to traditional capture methods. Therefore, combining eDNA with traditional methods is a more effective method for analyzing eDNA metabarcoding, following which the protocols of both quantitative methods can be designed to explore the regularity of eDNA quantification.Keywords：environmental DNA;traditional capture method;fish communities;habitat differences;Erhai Lake8|6|0Updated：2024-11-19
- Abstract：Oyster cultivation is a pivotal economic industry in Hainan Island, South China, where a high oyster species diversity is shown. However, the specific distribution and biodiversity of oyster resources in the island have remained unclear. To elucidate the diversity of oyster species and their distribution there, 307 oyster samples were collected from 29 sites in the intertidal zone around the island, and were identified using both morphological and molecular approaches. A minimum of 12 oyster species were identified in taxonomy, including Crassostrea species (C. gigas angulata, C. sikamea, C. iredalei, C. dianbaiensis, C. talonata, C. ariakensis, and C. hongkongensis), and Saccostrea species (S. malabonensis, S. mordax, S. echinata, S. circumsuta, and S. mordoides). The results revealed a remarkable diversity of oyster species along the coast of the island. Particularly noteworthy are that S. malabonensis and S. mordax constituted 36% and 22% of the collected specimens, respectively. This study provided a comprehensive overview on current state of oyster biodiversity in Hainan, serving as a valuable reference for conservation and research on species distribution and resource dynamics in oyster populations.Keywords：distribution of oysters;Crassostrea;Saccostrea;oyster resource11|7|0Updated：2024-11-19
Ecology
- Abstract：The model diatom Phaeodactylum tricornutum is considered a promising source of various high value bioproducts, and developing cultivation processes is crucial for its commercialization. Although mixotrophy and heterotrophy have been recommended as effective strategies for microalgal cultivation, previous studies on P. tricornutum have yielded conflicting results in terms of cultivating this microalga. To verify the capacity of this microalga utilizing external organic carbon, both heterotrophic and mixotrophic cultivation with varied carbon sources were performed using an axenic strain. The results demonstrate that glycerol was the only organic carbon that substantially stimulated the growth of P. tricornutum in the presence of light. Sodium acetate (NaAc) at low concentrations could also promote growth, while at high concentrations led to severe inhibition under mixotrophic conditions. The addition of glucose imposed no appreciable impact on either cell density or biomass concentration, confirming that P. tricornutum cannot metabolize external glucose. Subsequently, a comparative analysis between mixotrophy and autotrophy was performed to reveal the influences of glycerol on the cellular metabolism based on growth performances, biochemical compositions, and chlorophyll fluorescence parameters. Results also indicate that the addition of glycerol did not have detrimental effects on the capacity of either pigments biosynthesis or photosynthesis, but enhanced the saturated fatty acids and reduced the unsaturated fatty acids.Keywords：Phaeodactylumtricornutum;autotrophy;mixotrophy;fucoxanthin;glycerol16|6|0Updated：2024-11-19
- Abstract：Previous studies have revealed that ammonia nitrogen has several adverse effects on clam Ruditapes philippinarum. However, knowledge is lacking regarding the related proteins involved in the toxicological responses, which is vital to elucidate the underlying mechanism of ammonia nitrogen. In this study, clams R. philippinarum were exposed to ammonia nitrogen for 21 d at two environmentally relevant concentrations. The tandem mass tags approach (TMT) was applied to assay the differentially expressed proteins (DEPs) in clam gill tissues on the 3rd and 21st day. Finally, a total of 7 263 proteins were identified. Bioinformatics analyses revealed that clam protein profiles changed in dose- and time-dependent manner after ammonia nitrogen exposure. We inferred that the clams may face heavy challenges after ammonia exposure, such as unbalanced gender ratio, lysosomal disease, energy lack, neurological disorders, altered glutamine metabolism, increased lipid synthesis, and impaired immunity. Variation profiles of enzyme activities of glutaminase and glutamine synthase provided direct evidence to verify the related inference from proteome data. Most of the inferred toxic effects merit further study. This study identified important proteins related to ammonia nitrogen toxicity in the clam and indicated the severe stress of marine ammonia pollution on the healthy development of mollusc aquaculture.Keywords：ammonia nitrogen;Ruditapesphilippinarum;proteomic analysis;toxicity8|10|0Updated：2024-11-19
- Abstract：Antarctic krill Euphausia superba plays a key role in the Antarctic food web. The trophic linkage between krill and other macro-organisms has been studied in the past decades, but the variability of parasites in krill is less studied and remains poorly understood. Therefore, it is important to understand the factors that influence abundance and infection of parasites in krill. Moreover, the relationship between the infection intensity of parasite and krill diet needs to be clarified, which is helpful for understanding the role of parasite in the food web. We investigated the abundance of the highly prevalent gregarine parasites in the digestive tract of krill and the factors influencing the gregarine infection to krill in the East Antarctic. The infection rate of Cephaloidophora pacifica Avdeev, 1985 to krill (n=50 individuals) was 94%. The results of generalized linear model show the infection intensity of C. pacifica to the host was related significantly to the station, krill size, and maturity stage, but not the food species and abundance in the stomach of krill. Abundance of C. pacifica in krill differed among stations, and the lowest abundance occurred in the station nearest to the coast. Gregarines abundance varied among sexual maturity stages of krill and increased with krill size.Keywords：Cephaloidophora pacifica;Euphausiids;parasite;diet;dinoflagellate9|8|0Updated：2024-11-19
- Abstract：The body surface of crustaceans is covered with a sturdy shell. The growth and development of crustaceans are realized through molting. Neocaridina denticulata sinensis is a suitable candidate for crustacean scientific research. Two calcium-associated cuticular protein genes, named NdCAP-1 and NdCAP-2, were obtained from N. denticulata sinensis. Molecular docking simulated the binding effect of both proteins and calcium ions. Semi-quantitative reverse transcription PCR results show that NdCAP-1 is expressed in D2–4 stage, NdCAP-2 expressed in D2–4 and A–B stages, and both were significantly expressed in the cephalothorax cuticle and pereiopods. Then, it was revealed that NdCAP-1 and NdCAP-2 are regulated by NdEcR-mediated 20E signaling pathways. Knockdown of NdCAP-1 and NdCAP-2 was observed to cause surface defects. The recombinant proteins (rNdCAP-1 and rNdCAP-2), obtained by prokaryotic expression, had calcium-binding and chitin-binding ability, inhibited formation of calcium carbonate precipitate. These results show that calcium-associated cuticular proteins play important roles in cuticle formation and calcification.Keywords：Neocaridinadenticulatasinensis;calcium-associated cuticular protein;molting cycle;RNAi;calcium-binding ability12|3|0Updated：2024-11-19
- Abstract：The mechanisms underlying sex determination and differentiation have long intrigued researchers in the fields of development and evolutionary biology. The roughskin sculpin (Trachidermus fasciatus Heckel), displaying sexual dimorphism, provides an ideal model for studying the mechanisms. However, both genetic and genomic information concerning sex determination and differentiation, such as gonadal transcriptome data in roughskin sculpin, are lacking. Here, we present the first gonadal transcriptomes of roughskin sculpin and identify sex-related genes. We identified 8 531 differentially expressed genes (DEGs), among them 4 065 were upregulated in the ovary and 4 466 upregulated in the testis. Several sex-related gene ontology (GO) terms were enriched in ovary-biased genes, including “binding of sperm to zona pellucida”, “egg coat formation”, “positive regulation of acrosome reaction”, “cell division”, and “cell cycle”, while the GO terms such as “spermatogenesis”, “sperm axoneme assembly”, “cilium assembly”, “cilium movement”, and “cilium movement involved in cell motility” were enriched in testis-biased genes. Moreover, six KEGG pathways were significantly enriched in the ovary, whereas only one was enriched in the testis. Of these DEGs, 40 sex-related genes were identified, which including 26 testis-biased genes (such as Dmrtb1, Gsdf, Sox9b, Wnt4b, Tcp11l2, and Efhb), and 14 ovary-biased genes (such as Cyp19a1a, Foxh1, Foxr1, Gdf3, Hsd17b12, and Igf2bp3). This gonadal transcript dataset would broaden our understanding of sex determination and differentiation mechanisms in roughskin sculpin, expand the genomic database, support future studies on sex-related gene functions, and facilitate molecular biology research into roughskin sculpin.Keywords：Trachidermusfasciatus;transcriptome;ovary;testis;sex-related gene10|4|0Updated：2024-11-19
Biology
- Abstract：The Atlantic tripletail (Lobotes surinamensis) is a high revenue-generating fish species predominantly caught by mechanized artisanal fishers community and the most available member of its family in Bangladesh. This is a ground work of fish stock assessment study in the Bay of Bengal region to explore the life history parameters and associated biomass of this species, using three length-based approaches of TropFishR, the length-based Bayesian biomass estimation (LBB), and Froese’s length-based indicators (LBIs). An almost homogenous body growth pattern (b=3.07; R2=0.98) was observed in the length-weight relationship of tripletail. The life history parameters for tripletail, as determined by the von Bertalanffy Growth Function (VBGF) model, were L∞=113.36 cm and k=0.51/a. The length converted catch curve (LCCC) yielded an estimation of the total mortality (Z=1.77/a), with the natural mortality estimated at (M=0.53/a) and the fishing mortality estimated at (F=1.24/a). But, the ratio of mortality (F/M=0.15) by LBB captured the non-fully exploited status of biomass (B/BMSY=2.1). LBI analysis indicated that the tripletail fishery’s spawning stock biomass is greater than the target and limit reference points, indicating a healthy state of biomass.Keywords：Bay of Bengal;Lobotessurinamensis;TropFishR;length based indicator (LBI);length-based Bayesian biomass estimation (LBB);Bangladesh11|4|0Updated：2024-11-19
- Abstract：To adapt to the change of aquaculture workshop site, optimize the shape of aquaculture tanks and improve the utilization rate of breeding space, it is necessary to determine the appropriate length-width ratio parameters of aquaculture tanks. In this paper, computational fluid dynamics (CFD) technology is adopted to study the flow field performance of aquaculture tanks with different L/B ratios (L: the length; B: the width, of aquaculture tank) and different jet direction conditions (lengthways jet and widthways jet). A three-dimensional numerical calculation model of turbulence in rounded rectangle aquaculture tanks in dual-diagonal-inlet layout was established. Jet directions are arranged lengthways and widthways, and the water flow velocity, resistance coefficient change, vorticity, etc. are analyzed under two working conditions. Results show that the flow field performance in aquaculture tank decreases with the increase of the L/B ratio. The flow field performed well when L/B was 1.0–1.3, sharply dropped at 1.4–1.6, and poor at 1.7–1.9. The results provided a theoretical basis for the design and optimization in flow field performance of the industrialized circulating aquaculture tanks.Keywords：aquaculture tank;length-width ratio;computational fluid dynamic;hydrodynamic16|7|0Updated：2024-11-19
- Abstract：Probiotics are live microbial food supplements that have been shown to have beneficial effects on animal health. Endogenous probiotic bacteria have long been used for their proposed health-promoting properties and have become a hot research topic in growth improvement in aquaculture. The endogenous probiotic bacteria from intestines of Macrobrachium rosenbergii (giant river prawn) was explored for their probiotic potential, from which 367 bacterial strains were isolated from the intestine of M. rosenbergii. After 16S rDNA sequence analysis, 234 isolates were identified as Lactococcus garvieae, which accounted for 63.76% of the total number of culturable intestinal bacteria, suggesting that this bacterium was the main component of the microbiota. Furthermore, to reveal the probiotic properties of L. garvieae, this isolated bacterial strain was characterized morphologically, physiologically, and biochemically. Its enzyme production capacity, bacteriostatic activity, and resistance to acid, high temperature, and pH, were assessed. In vitro experiments showed that the L. garvieae (No. C6a2) had a fast growth rate and entered the logarithmic phase rapidly. Besides, it had characteristics of acid-production and resistance, enzyme-producing capacity, and strong antibacterial activity against pathogenic Staphylococcus aureus, Aeromonas hydrophila, and Aeromonas veronii. However, it lacked the ability to tolerate high temperature. Our results provide novel data to deepen our understanding of the intestinal bacteria structure of M. rosenbergii and valuable information for probiotic screening and the application for M. rosenbergii.Keywords：Macrobrachium rosenbergii;intestinal bacteria;probiotic;Lactococcus garvieae8|6|0Updated：2024-11-19
Aquaculture and Fisheries
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