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Volume 42 ， Issue 4 ， 2024
- Abstract：A 110-year ensemble simulation of an ocean general circulation model (OGCM) was analyzed to identify the modulation of salinity interdecadal variability on El Niño-Southern Oscillation (ENSO) amplitude in the tropical Pacific during 1901–2010. The simulating results show that sea surface salinity (SSS) variation in the region exhibits notable and coherent interdecadal variability signal, which is closely associated with the Interdecadal Pacific Oscillation (IPO). As salinity increases or reduces, the SSS modulations on ENSO amplitude during its warm/cold events vary asymmetrically with positive/negative IPO phases. Physically, salinity interdecadal variability can enhance or reduce ENSO-related conditions in upper-ocean stratification, contributing noticeably to ENSO variability. Salinity anomalies associated with the mixed layer depth and barrier layer thickness can modulate ENSO amplitude during positive and negative IPO phases, resulting in the asymmetry of sea surface temperature (SST) anomaly in the tropical Pacific. During positive IPO phases, SSS interdecadal variability contributes positively to El Niño amplitude but negatively to La Niña amplitude by enhancing or reducing SSS interannual variability, and vice versa during negative IPO phases. Quantitatively, the results indicate that the modulation of the ENSO amplitude by the SSS interdecadal variability is 15%–28% during negative IPO phases and 30%–20% during positive IPO phases, respectively. Evidently, the SSS interdecadal variability associated with IPO and its modulation on ENSO amplitude in the tropical Pacific are among factors essentially contributing ENSO diversity.Keywords：El Niño-Southern Oscillation (ENSO) amplitude;interdecadal Pacific Oscillation (IPO);ocean salinity variability;tropical Pacific;upper-ocean stratification28|16|0Updated：2024-10-11
- Abstract：Marine heatwaves (MHWs) can cause irreversible damage to marine ecosystems and livelihoods. Appropriate MHW characterization remains difficult, because the choice of a sea surface temperature (SST) temporal baseline strongly influences MHW identification. Following a recent work suggesting that there should be a communicating baseline for long-term ocean temperature trends (LTT) and MHWs, we provided an effective and quantitative solution to calculate LTT and MHWs simultaneously by using the ensemble empirical mode decomposition (EEMD) method. The long-term nonlinear trend of SST obtained by EEMD shows superiority over the traditional linear trend in that the data extension does not alter prior results. The MHWs identified from the detrended SST data exhibited low sensitivity to the baseline choice, demonstrating the robustness of our method. We also derived the total heat exposure (THE) by combining LTT and MHWs. The THE was sensitive to the fixed-period baseline choice, with a response to increasing SST that depended on the onset time of a perpetual MHW state (identified MHW days equal to the year length). Subtropical areas, the Indian Ocean, and part of the Southern Ocean were most sensitive to the long-term global warming trend.Keywords：marine heatwaves (MHWs);ensemble empirical mode decomposition (EEMD);long-term temperature (LTT) trend;total heat exposure (THE)23|24|0Updated：2024-10-11
- Abstract：Rapidly monitoring regional water quality and the changing trend is of great practical and scientific significance, especially for the Beijing-Tianjin-Hebei (BTH) region of China where water resources are relatively scarce and inland water bodies are generally small. The remote sensing data of the GF1 satellite launched in 2013 have characteristics of high spatial and temporal resolution, which can be used for the dynamic monitoring of the water environment in small lakes and reservoirs. However, the water quality remote sensing monitoring model based on the GF1 satellite data for lakes and reservoirs in BTH is still lacking because of the considerable differences in the optical characteristics of the lakes and reservoirs. In this paper, the typical reservoirs in BTH-Guanting Reservoir, Yuqiao Reservoir, Panjiakou Reservoir, and Daheiting Reservoir are taken as the study areas. In the atmospheric correction of GF1-WFV, the relative radiation normalized atmospheric correction was adopted after comparing it with other methods, such as 6S and FLAASH. In the water clarity retrieval, a water color hue angle based model was proposed and outperformed other available published models, with the R2 of 0.74 and MRE of 31.7%. The clarity products of the four typical reservoirs in the BTH region in 2013–2019 were produced using the GF1-WFV data. Based on the products, temporal and spatial changes in clarity were analyzed, and the main influencing factors for each water body were discussed. It was found that the clarity of Guanting, Daheiting, and Panjiakou reservoirs showed an upward trend during this period, while that of Yuqiao Reservoir showed a downward trend. In the influencing factors, the water level of the water bodies can be an important factor related to the water clarity changes in this region.Keywords：GF1 satellite;atmospheric correction;clarity;Beijing-Tianjin-Hebei;spatial and temporal change analysis29|17|0Updated：2024-10-11
Physics
- Abstract：Coastal tidal creeks are important channels for exchanges of material and energy between sea and land, and play an important role in the ecological protection of tidal flats. Although tidal creeks have evolved differently in various regions, the evolutionary process of tidal creeks in the Huanghe (Yellow) River delta of China, one of the most active deltas worldwide, is not entirely clear. Therefore, the evolution of tidal creeks in the delta from 1981 to 2021 was investigated by quantitatively analysing the tidal creeks and developing a standard for dividing their evolution periods. Visual interpretation and supervised classification methods were applied to the Landsat images to extract the tidal creek network, and 17 groups of tidal creek systems were selected. Results indicate that Creek S1 was the most developed creek for having 113 tidal creeks totaling 65.8 km in length, while Creek E3 had the fastest growth rate for having average annual increase of 1.9 km. Meanwhile, the level of tidal creeks increased, the average and median lengths of tidal creeks increased, and the number of tidal creeks decreased since 1981. The evolution of the tidal creek system could be divided into four stages, namely, rising, developing, stabilizing, and degrading. Analyses of a representative tidal creek show that there was no degenerated tidal creek during the rising period, with an increase in the number of 50 and a length increase of 57.9 km between 1981 and 1989. The proportion of new tidal creeks in the developing period was more than 50% and the new tidal creeks in the stabilizing period were equal to the degraded tidal creeks. Extinct tidal creeks were greater than 50% during the degrading period. There was no fixed order of tidal creek evolution in each period, and there may be a skip in evolution. Our findings provided a reference for studying the evolution of tidal creeks.Keywords：tidal creek;evolution pattern;remote sensing;Huanghe (Yellow) River delta41|7|0Updated：2024-10-11
- Abstract：The northward subduction of the Neo-Tethys oceanic crust triggered multiple magmatic activities in the West Myanmar Arc, which in turn influenced the deposition of sedimentary pyroclastic rocks from the Cretaceous to Eocene strata in the Central Myanmar Basin (CMB). The pore structure of these lithologic reservoirs is complex and rich in tuffaceous sandstone, which plays an adverse role in reservoir development in this region. To understand the development characteristics and genetic mechanism of the pyroclastic rocks within three sets of reservoirs in this area, a comprehensive analysis was conducted through borehole core observations, thin section identification, scanning electron microscope analysis, and mercury injection tests. The tuffaceous sandstone from the upper Cretaceous to the Eocene is dominated by intermediate-acid volcanic rock debris. The pyroclastic rocks exhibit evident chloritization and ironization, with residual intergranular pores being the principal type accompanied by a smaller amount of intergranular dissolved pores and intragranular dissolved pores. The highest porosity is observed in the Eocene tuffaceous sandstone, ranging from 8% to 12%. The Late Cretaceous to Paleocene sandstones exhibit lower porosity levels of only 4%–6%. These reservoirs are characterized by their low-porosity and low-permeability. Despite the presence of a good source rock in this area, the volcanic debris particles filling the pores, as well as their subsequent devitrification, chloritization, and limonite mineralization, result in pore throat blockage and narrowing. The reservoirs in this area are small in size, exhibit poor reservoir connectivity and lateral continuity, and fail to meet the necessary conditions for commercial-scale hydrocarbon accumulation and migration.Keywords：Central Myanmar Basin;back-arc basin;reservoir characteristic;volcanic debris31|17|0Updated：2024-10-11
- Abstract：Salinity is a crucial property of water body and is essential for the restoration of paleoecology and paleoenvironment. However, the theoretical method of application of elemental geochemical proxies to paleosalinity reconstruction is still underdeveloped. Moreover, accurate determination and reconstruction of paleosalinity and its variation in an offshore lacustrine basin have been extremely challenging thus far. This study presents detailed elemental geochemical investigations from the Zhanhua Sag in the southern Bohai Bay Basin to reconstruct the salinity variation in the Paleogene Eocene Shahejie Formation (50.8–33.9 Ma). Based on the variation of strontium barium ratio (Sr/Ba) and boron gallium ratio (B/Ga), we determined three typical salinity types of water body: salty water (Sr/Ba>0.5, B/Ga>6), brackish water (0.2<Sr/Ba<0.5, 3<B/Ga<6), and fresh water (Sr/Ba<0.2, B/Ga<3), after eliminating carbonate-sourced strontium (Sr). The salinity values following Couch’s paleosalinometer ranged from 3.1 to 11.9, reflecting the overall characteristics of oligohaline (0.5<salinity value<5) to mesohaline (5<salinity value<18) brackish water. All proxies yielded similar trends in paleosalinity variation, demonstrating a clear trend of rising and then declining from 50.8 Ma to 33.9 Ma. We considered that the B/Ga ratio had the highest reliability and resolution in determining the salinity types of water body in the study area. The environmental factors causing paleosalinity variation were also thoroughly analysed based on the temporal relationship among the salinity types of watermasses, paleoclimate characteristics from pollen records, and marine transgression events from marine fossils. Our research established a model of paleoclimatic and eustatic mechanisms to explain paleosalinity variation, providing reasonable and integral driving forces for the salinity variation of all offshore lacustrine basins.Keywords：paleosalinity;paleoclimate;Zhanhua Sag;Middle-Upper Eocene;Shahejie Formation26|20|0Updated：2024-10-11
- Abstract：A new hydrothermal field (Tianshi) was discovered on the rift valley wall through plume anomaly surveys and geological work conducted in 2012 and 2018 between 2°35′N and 2°43′N of the slow-spreading Carlsberg Ridge (CR). Here, the results of two expeditions conducted to detect and characterize the new hydrothermal field are reported. Mineralogical and geochemical data, as well as 14C ages of a sediment core collected near the field are presented to reveal the hydrothermal history. Results show that the Tianshi field is a basalt-hosted hydrothermal system. Geochemical data of the sediments collected near the field indicate a strong hydrothermal contribution, and hydrothermal Fe and Cu fluxes range from 30 to 155 mg/(cm2·ka) and 0.59 to 11.49 mg/(cm2·ka), respectively. Temporal variations in the fluxes of hydrothermal Fe indicate that there have been at least three amplified hydrothermal venting events (H1, H2, and H3) in the Tianshi field over the last 35.2 ka, in 28.6–35.2 ka BP, 22.0–27.6 ka BP, and 1.2–11.4 ka BP, respectively. Hydrothermal event H2 was driven by an increased magmatic production associated with sea level fall during the Last Glacial Maximum, while event H3 was promoted by tectonic activity associated with a rapid sea level rise. This study further verified the role of sea level change in modulating hydrothermal activity on mid-ocean ridges.Keywords：plume anomaly;sediment core;new hydrothermal field;hydrothermal history;Carlsberg Ridge16|10|0Updated：2024-10-11
Geology
- Abstract：The Ninety East Ridge in the Indian Ocean has complex and unique characteristics. The concentrations and distribution characteristics of 10 trace metals (V, Cr, Mn, Fe, Co, Ni, Cu, Cd, Pb, and U) in seawater from the Ninety East Ridge in the Indian Ocean were investigated. Results show that the average concentrations of different trace metals in all the collected seawater samples were 1.134 μg/L for V, 0.158 μg/L for Cr, 0.489 μg/L for Mn, 0.427 μg/L for Fe, 0.011 μg/L for Co, 0.395 μg/L for Ni, 0.403 μg/L for Cu, 0.097 μg/L for Cd, 0.139 μg/L for Pb, and 3.470 μg/L for U. Differences in the horizontal and vertical distributions of all measured trace metals were revealed, and the occurrence of high concentrations was nonuniform. In addition, the significant differences in the concentration distribution of different trace metals in seawater on both sides of the Ninety East Ridge present regional segmentation in the area for various trace metals in deep sea water. This study provided basic data for future investigations on the environmental and ecological impact of trace metals in the Indian Ocean and the potential water mass transport mechanism.Keywords：trace metal;environmental characteristic;Ninety East Ridge;seawater;Indian Ocean19|7|0Updated：2024-10-11
Chemistry
- Abstract：Variations of picoplankton groups were investigated over a one-month period in Daya Bay and Sanya Bay, in the northern South China Sea. The two coastal regions exhibited different variation patterns in physicochemical parameters. Moreover, the diel variations of picoplankton groups were different between the two bays. The abundance of the picoplankton in Sanya Bay displayed a pronounced diel variation, while it was not significant in Daya Bay. In addition, some similar patterns of picoplankton abundance were discovered. In the two bays, virioplankton exhibited the smallest fluctuation range, whereas picocyanobacteria fluctuated most markedly. The fluctuation range of picoplankton groups was larger in spring tide than in neap tide, especially in Sanya Bay. Random forest model analysis demonstrated that the variation of picoplankton groups was attributed to physical and chemical factors in Sanya Bay and Daya Bay, respectively. Therefore, our findings suggest that virioplankton abundance can persist more stably in response to changing environmental conditions compared to bacterioplankton and picophytoplankton.Keywords：diel variation;abundance;picoplankton group;virioplankton;picocyanobacteria16|12|0Updated：2024-10-11
- Abstract：Based on the reconstructed MODIS data and ECMWF reanalysis data from 2003 to 2021, spatial correlations between chlorophyll a (Chl a) and sea surface temperature (SST), photosynthetically available radiation (PAR), aerosol optical thickness (AOT), and wind speed (WS) in the Bohai Sea were analyzed from the perspective of time domain and frequency domain. Results indicate that the frequency-domain analysis was more conducive to revealing the correlations between Chl a and environmental factors. The spatial pattern of time-domain correlations was similar to the isobaths of the Bohai Sea, which was positive in shallow waters and negative in deep waters for SST, PAR, and AOT, and was reversed for WS. Frequency-domain correlations were obtained by performing Fourier Transform and were higher than correlations in time domain. The spatial distributions indicated that the effects of SST and PAR on Chl a were greater than AOT and WS in the Bohai Sea. Additionally, cross-spectrum analysis was applied to explore the response relationships. A depth-dependent pattern was shown in correlations and time lags, indicating that the influential mechanism of environmental factors on Chl-a concentration is related to seawater depth.Keywords：chlorophyll a (Chl a);frequency domain;spatial correlation;Bohai Sea23|13|0Updated：2024-10-11
- Abstract：To investigate the dominant species and interspecific association in the phytoplankton community of the Feiyun River basin in Zhejiang Province, East China, the main stream and the Shanxi-Zhaoshandu Reservoir in the downstream were chosen as the study area, for which 22 sampling sites were designated. Sampling was conducted in September 2021, January, May, and July 2022. Phytoplankton species were identified from both quantitative samples and in-vivo observations. Phytoplankton was quantified by direct counting. Results show that there were 98 species belonging to 6 phyla and 78 genera. In addition, to clarify the niches of the dominant phytoplankton species and their interspecific association, the dominance index was calculated, and a comprehensive analysis was conducted including niche width, niche overlap value, ecological response rate, overall association, chi-square test, and the stability. The phytoplankton community exhibited characteristics of a Cyanobacteria-Chlorophyta-Diatom type community, showing higher diversity in spring and lower diversity in summer. Among 11 dominants phytoplankton species from 3 phyla, both frequency and dominance degree varied seasonally, of which Microcystis sp. was the dominant species in Spring, Autumn, and Winter. The niche widths of the dominant species ranged from 0.234 to 0.933, and were categorized into three groups. The niche overlap values of the 11 dominant species ranged from 0.359 to 0.959, exhibiting significant seasonal differences—highest in winter followed by autumn, spring, and summer in turn. The overall correlation among dominant species in all four seasons revealed a non-significant negative association, resulting in an unstable community structure. A significant portion (84.2%) of species pairs displayed positive associations, suggesting a successional pattern where Diatoms dominated while other dominant species shared resources and space. Despite this pattern, stability measurements indicated that the dominant species community remained unstable. Therefore, careful monitoring is recommended for potential water environment issues arising from abnormal proliferation of dominant species in the watershed during winter. This research built a theoretical foundation with a data support to the early warning of eutrophication and provided a reference for water resources management in similar watersheds along the eastern coast of China.Keywords：phytoplankton;dominant species;niche;interspecific association;Feiyun River basin13|12|0Updated：2024-10-11
- Abstract：Particulate organic matter (POM) is an important energy source for aquatic consumers, understanding its origin and composition is essential for understanding the energetic dynamics of aquatic environments. The aim of this study was to analyze the relationship between POM and phytoplankton (isotopic values and chlorophyll concentration) and abiotic variables during dry and rainy seasons. Sampling was conducted in rivers and lagoons in the floodplain of the Upper Paraná River. We found a greater difference in δ13C values of POM between sampling points than between seasons, indicating that the composition of regional sources influences the composition of POM more than dry and rainy seasons. In addition, the concentration of chlorophyll during the dry season was positively correlated with δ13C values during that rainy period. Additionally, we found a relationship between factors limiting the growth of phytoplankton and δ13C values of POM, such as phosphate ions, indicating that variables that regulate phytoplankton growth tend to influence the composition of POM in river floodplains. Therefore, maintaining the variables that regulate the phytoplankton community is of fundamental importance for the composition of POM, an important energy source in aquatic environments.Keywords：freshwater;wetland;stable isotopes;food web;subtropical environment20|4|0Updated：2024-10-11
- Abstract：The increasing global concern regarding plastic pollution has prompted the research into the consequences of microplastics (MPs) on aquatic ecosystems. Fairy shrimp Branchinella kugenumaensis are freshwater planktonic organisms that have existed for 250 million years. This study aimed to uncover the harmful effects of MPs, with a particular focus on their size variations (0.1, 1, and 5 μm), on the fairy shrimp. We focused on how MPs could significantly affect the survival and growth of fairy shrimp. Notably, larger MPs, especially those measuring 5 μm, caused higher mortality rates and hindered the growth compared to smaller ones. The impact of MPs continued even subsequent to depuration in clean water. The accumulation of MPs within the intestines of fairy shrimp resulted in intestinal blockages, disrupted excretory functions, and harmed intestinal epithelial cells. Examinations at the histological, cellular, and molecular levels showed that exposure to MPs triggered necroptosis in intestinal cells, accompanied by alterations in pathways related to transcription, translation, digestion, energy metabolism, and neurological functions. Furthermore, the effects of MPs on gene expression and pathways varied based on particle size, with larger MPs having a more significant effect and causing a strong response in xenobiotic biodegradation and metabolism pathways. We suggest that the increasing severity of MPs pollution could pose a significant threat to the survival of fairy shrimp. This study provided vital insights into the complex relationship between microplastics and aquatic organisms, and highlighted the urgent need to address the potential devastating impact of plastic pollution on freshwater ecosystems. Additionally, due to their rapid growth, strong reproductive capacity, sensitivity, and ease of cultivation, fairy shrimp hold the potential candidate to serve as a model organism for studying the effects of MPs and other pollutants on freshwater ecosystems.Keywords：microplastic;freshwater ecosystem;toxic effects;fairy shrimp;model organism15|10|0Updated：2024-10-11
- Abstract：To effectively remove n-propylbenzene (n-PBZ) and isopropylbenzene (i-PBZ) leaked into seawater using Rhinomonas reticulata S6A (a newly isolated marine microalga), the effects of three inorganic nutrients and four environmental factors on their degradation were determined after 7 d of inoculation. Results show that NaNO3 at 300 mg/L caused a higher removal efficiency of both n-PBZ and i-PBZ (44.79% and 39.26%), while for NaH2PO4·H2O, greater removal rates of two PBZs (47.30% and 42.23%) were achieved at 30 and 20 mg/L, respectively. NaHCO3 supplementation (500–750 mg/L) resulted in a large reduction (43.67%–45.04%) in i-PBZ concentration. The change in seawater pH (from 6 to 9) did not affect the elimination of n-PBZ and i-PBZ. The most suitable salinity and temperature were 30 and 25–30 °C, respectively, leading to the PBZs removal of ~40%. Light intensity exhibited significant influence on elimination of PBZs, and the maximum removal efficiencies of 56.07% (n-PBZ) and 55.00% (i-PBZ) were recorded under 200 and 600 μmol/(m2·s), respectively. In addition, the microalga could still remove PBZs when it failed to grow well due to darkness, strong light, low temperature, or low salinity, which might mean that good growth of alga is not always a necessary condition for PBZs removal. Therefore, attention should be paid to the suitability of nutrient levels and environmental conditions (excluding pH) in seawater when using microalgae for bioremediating PBZs-contaminated seawater.Keywords：propylbenzene (PBZ);Rhinomonas reticulata;seawater;inorganic nutrient;environmental factor16|3|0Updated：2024-10-11
- Abstract：Since 2007, the Yellow Sea green tide has broken out every summer, causing great harm to the environment and society. Although satellite remote sensing (RS) has been used in biomass research, there are several shortcomings, such as mixed pixels, atmospheric interference, and difficult field validation. The biomass of green tide has been lacking a high-precision estimation method. In this study, high-resolution unmanned aerial vehicle (UAV) RS was used to quantitatively map the biomass of green tides. By utilizing experimental data from previous studies, a robust relationship was established to link biomass to the red-green-blue floating algae index (RGB-FAI). Then, the lab-based model for green tide biomass from visible images taken by the UAV camera was developed and validated by field measurements. Results show that the accurate and cost-effective method is able to estimate the green tide biomass and its changes in given local waters of the near and far seas. The study provided an effective complement to the traditional satellite RS, as well as high-precision quantitative techniques for decision-making in disaster management.Keywords：green tide;biomass estimation;quantitative technique;Yellow Sea;unmanned aerial vehicle (UAV);remote sensing (RS)24|18|0Updated：2024-10-11
- Abstract：Ulvaprolifera is the most common specie causative to green tide, and its growth is sensitive to temperature stress. However, the mechanisms of U.prolifera response to temperature stress remain elusive. In this study, high temperature (36 °C) stimulus promoted the death of unformed cell wall protoplasts and delayed the division of formed cell wall protoplasts, while low-temperature (4 °C) stimulus did not, suggesting that the mechanisms of the response of U. prolifera to high and low-temperature stresses are different. Transcriptome results show that proliferation-related genes were differentially expressed under high and low-temperature stresses, especially the proliferating cell nuclear antigen (PCNA) and cyclins (CYCs). Subsequently, the interaction between PCNA and Cyclin A was confirmed by Co-immunoprecipitation, yeast two-hybrid, and so on. Furthermore, high- and low-temperature stresses induced the expression of PCNA and CyclinA in varying of degrees, and activated extracellular signal-regulated kinase (ERK) signal pathway. These results suggest, PCNA, CyclinA, and ERK signal pathway played important roles in the resistance of U. prolifera to temperature stress. Interestingly, high-temperature stress induced an increase of miR-2916 in abundance, and exhibiting reverse expression of PCNA; and PCNA was target gene of miR-2916, suggesting that miR-2916 protected U. prolifera from high-temperature stress via post-transcriptionally regulation of PCNA. This study laid a foundation for understanding the function of PCNA and CyclinA, moreover, it has a guiding significance to explore the mechanisms of the response to temperature stress from proliferation-related genes regulatory networks in U. prolifera.Keywords：UIvaprolifera;proliferating cell nuclear antigen;Cyclin A;extracellular signal-regulated kinase;microRNA;temperature stress15|5|0Updated：2024-10-11
- Abstract：Thermal stress causes the overproduction and toxic accumulation of reactive oxygen species (ROS), which seems to be correlated with coral bleaching and, ultimately, death. The reduction of ROS concentration within the coral holobiont could minimize the effects of thermal stress and support efforts to reduce coral decline globally. In the current study, we explored the physiological responses of Pocillopora damicornis to ROS-scavenging bacteria inoculation as well as the microbiome restructuring that correlates with P. damicornis’s resilience to thermal stress after probiotic inoculation. Inoculation of corals with ROS-scavenging bacteria enhanced coral health and reduced ROS concentration. Furthermore, the enhanced coral thermal resistance promoted by ROS-scavenging bacteria was also correlated with an overall coral microbiome restructuring. In addition, the complex network relationships between bacteria and Symbiodiniaceae in corals after ROS-scavenging bacteria inoculation contributed to corals’ resilience to high temperatures. Besides, coral heat tolerance bacterial biomarkers, such as Myxococcota, were enriched in corals with added ROS-scavenging bacteria. Collectively, our findings validate the selected ROS-scavenging bacteria as coral probiotics that could help corals resist thermal stress on a short timescale. Additionally, our data contribute to our understanding of the potential interactions between different members of the coral holobiont and the use of probiotics as tools to aid coral restoration efforts.Keywords：coral;beneficial microorganisms for corals (BMCs);Symbiodiniaceae;thermal stress;coral bleaching22|10|0Updated：2024-10-11
Ecology
- Abstract：The chloride channel 7 gene (CLC7) of the Hong Kong oyster Crassostrea hongkongensis was cloned and named ChCLC7. The cDNA was 2 572 bp in length, with a 5′ non-coding region containing 25 bp, a 3′ non-coding region containing 327 bp, and an open reading frame of 2 298 bp. ChCLC7 has 96.8% and 92.1% homology with CLC7 of Crassostrea gigas and Crassostrea virginica, respectively, and it was clustered with CLC7 of C. gigas and C. virginica. QRT-PCR showed that ChCLC7 was expressed in all eight tissues, with the highest in adductor muscle and second in gill. The ChCLC7 expression pattern in gill was altered significantly under high salinity stress with an overall upward and then downward trend. After RNA interference, the expression of ChCLC7 and survival rate of oyster under high salinity stress was reduced significantly, and so did the concentration of hemolymph chloride ion in 48–96 h after RNA interference. We believed that ChCLC7 could play an important role in osmoregulation of C. hongkongensis by regulating Cl⁻ transport. This study provided data for the analysis of molecular mechanism against oyster salinity stress.Keywords：Crassostrea hongkongensis;chloride channel 7;salinity stress;RNA interference14|12|0Updated：2024-10-11
- Abstract：Members of the family Scenedesmaceae are some of the most common algal taxa in inland ecosystems, and they are widely distributed in freshwaters, aerial, and sub-aerial habitats. With the continuous updating of methods, the classic morphological taxonomy of this family needs to be revised. In recent years, many genera of Scenedesmaceae have been established via the use of molecular methods. The phylogenetic relationships within Scenedesmaceae were analyzed using different molecular markers and morphological data, and the new freshwater genus Coccoidesmus Wang, Hou et Liu gen. nov. was described. Two new species in this genus were also described. Phylogenetic analysis based on tufA genes revealed that the new genus formed an independent clade closely related to Comasiella. However, these two genera are characterized by significant morphological differences in colony arrangement and cell shape. The chloroplast genome of the type species was assembled and annotated, and analyses of genome structure and sequences were conducted. More genome data could help clarify the phylogenetic relationships within this family.Keywords：phylogenetic;Scenedesmaceae;Coccoidesmus;morphology;chloroplast genome11|18|0Updated：2024-10-11
- Abstract：Chaetoceros Ehrenberg is one of the most diverse genera of planktonic diatoms. The species in section Chaetoceros are characterized by cells and setae having numerous chloroplasts and being widely distributed. However, the delimitations of some species are problematic because of limited morphological information in the classical descriptions. Monoclonal strains of the section Chaetoceros were established, morphological features were studied using light and electron microscopy, and the hypervariable D1–D3 region of the nuclear ribosomal large subunit gene was sequenced to address phylogenetic relationships. Fifteen species belonging to the section Chaetoceros were recorded, including two new species, C. hainanensis sp. nov. and C. tridiscus sp. nov. Chaetoceros hainanensis was characterized by straight chains, narrowly lanceolate to hexagonal apertures, sibling setae diverging in nearly right angles, stipule-shaped spines on terminal setae and arrowhead-shaped spines on intercalary setae. C. tridiscus had short straight chains, narrowly lanceolate apertures, arrowhead-shaped spines and circular poroids arranged in a grid pattern on terminal and intercalary setae. The phylogenetic analyses revealed six groups formed by 19 species within the section Chaetoceros, which was found to be monophyletic. The subdivision of the section is still not well understood. The morphological characters within each group varied considerably and molecular information on more species are needed to enrich the phylogenetic profiling.Keywords：morphology;large subunit ribosomal RNA encoding gene (LSU);section Chaetoceros;Chaetoceros hainanensis;Chaetoceros tridiscus14|8|0Updated：2024-10-11
- Abstract：We describe a new species of Discostella from Guiyang based on light and scanning electron microscopic observations, as well as molecular analysis. This species is morphologically distinguished from other species by a relatively smooth and slightly recessed central area with marginal striae of unequal lengths forked near the margin. Marginal fultoportulae and a single rimoportula are situated between every two costae or on the costae. Both morphological characters and the concatenated data of rbcL and SSU rDNA indicate that Discostella guiyangensis is a unique and new species. According to divergence time estimation analysis, Discostella guiyangensis is the oldest species among the Discostella species sequenced currently. In addition, we complement molecular data of Discostella asterocostata and Discostella stelligera.Keywords：Discostella;morphology;molecular analysis;divergence time estimation;new species17|16|0Updated：2024-10-11
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Morphology and phylogenetic placement of
Mallomonas vietnamica (Synurales, Chrysophyceae) from ChinaAbstract：The newly described chrysophyte, Mallomonas vietnamica, is reported for the first time in China from specimens collected in Guizhou Province, SW China. The morphological characteristics were studied using light and scanning electron microscopy. The species was described based on morphological characteristics, including cell size, scale size, dome, V-rib, and bristles. Subsequently, molecular sequencing of M. vietnamica was conducted and a phylogenetic tree was constructed based on concatenated SSU, LSU, and rbcL sequences. The phylogenetic tree led us to suggest raising a new section named Uncatusipedae for this species. This study provides new molecular data from the genus Mallomonas and enriches our understanding of the species diversity and geographical distribution of the genus Mallomonas in China.Keywords：Chrysophyta;Mallomonas vietnamica;phylogenetic study;taxonomy19|9|0Updated：2024-10-11
Biology
- Abstract：The farming of Scylla paramamosain with specific flavors has a higher commercial value, and the flavors are related to the integrated farming environment and non-volatile flavor substances, while the survival environment is one of the important ways to source gut microorganisms in the organism. In this study, the levels of dominant taxa in the gut flora of S. paramamosain from Mong Cai, Vietnam (VN), Taishan City, Guangdong Province (TS) of China, and Ninghai County, Ningbo City (NB) Zhejiang Province of China converged with those of S. paramamosain from Sanmen County, Ningbo City (CK1, CK2, and CK3) at 28 d of domestication. The top 15 genera with the highest abundance of VN, TS, and NB gut flora were the same as CK1, CK2, and CK3, but with different percentages, and gradually converged to CK1, CK2, and CK3, respectively, at 28 d of domestication. Correlation between intestinal flora and non-volatile flavor substances in the hepatopancreas at the percentage level of relative abundance of bacterial genera found that above 28 d of domestication, Muribaculaceae, Psychrilyobacter, Clostridia_vadinBB60_group, Halarcobacter Carboxylicivirga, Sediminispirochaeta may be the most important genera affecting flavor amino acids of VN. Sediminispirochaeta, Carboxylicivirga, Halarcobacter, Photobacterium, ZOR0006, Psychrilyobacter, and Pseudomonas may be the most important genera affecting flavor amino acids of NB. Sediminispirochaeta, Carboxylicivirga, Halarcobacter, Photobacterium, ZOR0006, Vibrio, and Sphingomonas may be the most important genera affecting flavor amino acids of TS. These results show that the intestinal flora structure of crabs from different areas were domesticated in the same area for at least 28 d before they converged to that of the domesticated crab, and the most important genera affecting the flavor amino acids of TS, VN, and NB were also identified. The results of this study provide a reference and basis for the technique of directional cultivation of the flavor quality of the crab.Keywords：survival environment;Scylla paramamosain;intestinal flora structure;non-volatile flavor substance;directional breeding12|6|0Updated：2024-10-11
- Abstract：The Pacific oyster Crassostrea gigas, one of the most exploited molluscs in the world, has suffered from massive mortality in recent decades, and the occurrence mechanisms have not been well-characterized. In this study, to reveal the relationship of associated microbiota to the fitness of oysters, temporal dynamics of microbiota in the gill, hemolymph, and hepatopancreas of C. gigas during April 2018–January 2019 were investigated by 16S rRNA gene sequencing. The microbiota in C. gigas exhibited tissue heterogeneity, of which Spirochaetaceae was dominant in the gill and hemolymph while Mycoplasmataceae enriched in the hepatopancreas. Co-occurrence network demonstrated that the gill microbiota exhibited higher inter-taxon connectivity while the hemolymph microbiota had more modules. The richness (Chao1 index) and diversity (Shannon index) of microbial community in each tissue showed no significant seasonal variations, except for the hepatopancreas having a higher richness in the autumn. Similarly, beta diversity analysis indicated a relatively stable microbiota in each tissue during the sampling period, showing relative abundance of the dominant taxa exhibiting temporal dynamics. Results indicate that the microbial community in C. gigas showed a tissue-specific stability with temporal dynamics in the composition, which might be essential for the tissue functioning and environmental adaption in oysters. This work provides a baseline microbiota in C. gigas and is helpful for the understanding of host-microbiota interaction in oysters.Keywords：Pacific oyster;associated microbiota;spatial compartmentalization;temporal stability22|16|0Updated：2024-10-11
- Abstract：To improve the self-cleaning ability of aquaculture tank and the efficiency of circulating water, physical and numerical experiments were conducted on the influence of inlet structure on sewage discharge in a rounded square aquaculture tank with a single inlet. Based on the physical model of the tank, analysis of how inlet structure adjustment affects sewage discharge efficiency and flow field characteristics was conducted to provide suitable flow field conditions for sinkable solid particle discharge. In addition, an internal flow field simulation was conducted using the RNG k-ε turbulence model in hydraulic drive mode. Then a solid-fluid multiphase model was created to investigate how the inlet structure affects sewage collection in the rounded square aquaculture tank with single inlet and outlet. The finding revealed that the impact of inlet structure is considerably affecting sewage collection. The conditions of C/B=0.07–0.11 (the ratio of horizontal distance between the center of the inlet pipe and the tank wall (C) to length of the tank (B)) and α=25° (α is the angle between the direction of the jet and the tangential direction of the arc angle) resulted in optimal sewage collection, which is similar to the flow field experiment in the rounded square aquaculture tank with single inlet and outlet. An excellent correlation was revealed between sewage collection and fluid circulation stability in the aquaculture tank. The present study provided a reference for design and optimization of circulating aquaculture tanks in aquaculture industry.Keywords：rounded square aquaculture tank;sewage collection characteristic;inlet structure;computational fluid dynamic13|9|0Updated：2024-10-11
Aquaculture and Fisheries
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