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Volume 41 ， Issue 4 ， 2023
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- Abstract：The Qarhan Salt Lake (QSL) in western China is K-Sr-Li-B-Br-Rb multi-resource coexisting Quaternary brine deposits. Significant research efforts have been directed to the origin of K-Li resources and evolutionary history of the QSL. However, the study on the different sources, recharge processes, and differential distribution patterns for these resource elements in brine deposits is still inadequate. Therefore, we measured Li-B concentrations and H-O-Sr-B isotopic compositions of different waters (river, spring, and brine) from the QSL, combined with the reported K-Sr contents and multiple isotopes of waters, to discuss the recharge, source of K-Sr-Li-B and their spatial distributions, by analogy with other evaporite basins in the world. The results show that: (1) the K-Li-B-Sr elemental concentrations of brines and their spatial distribution in the QSL are diverse; (2) high K and Sr values are distributed in Dabuxun and Qarhan sections, respectively, which are controlled by Ca-Cl springs in the northern QSL; on the contrary, Li and B values are enriched in the Bieletan section and are charged by thermal springs in the Kunlun Mountains; (3) the formation and evolution of Ca-Cl and thermal springs constrain fundamentally on the recharge processes of K-Sr and Li-B elements in the terminal salt lakes of the Qaidam Basin (QB); (4) some analogues of recharge processes limit the resource elements of the QSL and other salt lakes (Da Qaidam, Lop Nur, Zhabuye, Atacama, and Guayatayoc) in the world provides a reference for the resource exploration in deep formation waters in the evaporite basins.Keywords：K-Sr-Li-B elements;differential distribution;recharge process;Qarhan Salt Lake (QSL);analogue14|0|7Updated：2024-10-14
- Abstract：The Qaidam Basin (QB) is a concentrated distribution area and chemical industrial bases of salt lakes in China. Lakes in the QB have been expanding during the past 20 years. Rapid lake expansion resulted in some considerable scientific issues on the protection of salt lake resources and infrastructure, and monitoring of hydrological processes at the lake-basin scale. Although the spatial-temporal trends of lake changes on the Qinghai-Tibet Plateau (QTP) have been well documented, the underlying influencing mechanism and hydrogeological implications of rapid lake changes in the QB are not well understood. Three lakes in the northern QB were selected to investigate lake water level fluctuations on different time scales based on extensive in-situ monitoring and satellite observations. The influencing mechanism and hydrogeological implications of rapid changes of terminal lakes were discussed in combination with the reported increasing precipitation rate and mass balance of glaciers in the northern QTP. Results reveal the following: (1) the fluctuation pattern of Sugan Lake was asynchronous and out of phase with that of Xiao Qaidam and Toson lakes during the monitoring period; (2) Sugan Lake water rose gradually, and the rise interval was from late April to early July. In contrast, Xiao Qaidam and Toson lakes took on a rapid and steep rise, and the rise intervalwas from late July to September; (3) the influencing mechanisms for rapid lake fluctuations are controlled by different factors: glacier and snow melting with increasing temperature for Sugan Lake and increasing precipitation for Xiao Qaidam and Toson lakes; (4) in accordance with different intervals and influencing mechanisms of rapid lake expansions in the QB, hydrological risk precaution of lakes and corresponding river catchments was conducted in different parts of the basin. This study provided an important scientific basis for assessing the hydrological process and hydrological risk precaution, and protection of salt lake resources along with rapid lake expansions in the arid area.Keywords：lake level fluctuation;influencing mechanism;hydrogeological implication;northern Qaidam Basin;in-situ monitoring16|0|0Updated：2024-10-14
- Abstract：Zabuye Salt Lake (ZSL) in Xizang is the only saline lake in the world with natural crystalline lithium carbonate. As it is an important lithium production base in China, any changes of this lake are concerning. Global climate change (CC) has affected the hydrological conditions of glaciers, lakes, and ecosystems in the Tibetan Plateau (TP). With the aim of monitoring dynamic hydrological changes in ZSL and Lunggar Glaciers (LG) to identify factors governing lake changes, and to estimate the potential damage to grasslands and salt pans, Landsat remote sensing (RS) and meteorological data were used to do a series of experiments and analysis. Firstly, according to the spectral characteristics (SC), salt lake, glaciers, grasslands, and salt pans around the salt lake were extracted by band calculation (BC). Secondly, basin and water areas of the expanded lake were estimated using a shuttle radar topography mission (SRTM) digital elevation model (DEM). Thirdly, comprehensive analyses of lake and glacier area changes, and regional meteorological factors (annual average temperature, annual precipitation, and evaporation) were performed, and the results show that ZSL expanded at a rate of 5.28 km2/a, it is likely to continue expanding. Expansion was closely related to the large-scale melting of a glacier caused by rising temperatures. Continued lake expansion (LE) will exert different effects on surrounding grasslands and salt pans, 7.84 km2 of grassland and 2.7 km2 of salt pan will be submerged with every meter of water increase in the lake. Similar prediction methods was used to monitor other lakes on the TP. Mami Co, Selin Co, and Chaerhan salt lakes all expanded at different rates, and may potentially cause different levels of potential harm to surrounding grasslands and roads. Our study contributes to salt lake research and demonstrates the superiority of RS technology for monitoring saline lakes.Keywords：Tibetan Plateau;Zabuye Salt Lake;climate change;remote sensing;lake expansion22|0|3Updated：2024-10-14
- Abstract：About 23% of the surface area and 44% of the volume of all the lakes are occupied by saline lakes in the world. Importantly, agricultural diversion, illegal encroachment, pollution, and invasive species could cause these lakes to dry up completely or partially by 2025. Illegal saltpan encroachment is causing Sambhar, India’s largest saline lake, to shrink by 4.23% every decade. This study aims to characterize the soil parameters where halophytes are growing. A literature survey was conducted for halophytes and soil characteristics. The study area was divided into four zones for stratified random sampling. Soil sampling was conducted in February 2021. The soil indicators for halophyte selected were pH, electrical conductivity, moisture, salinity, organic carbon, and organic matter. The obtained results were interpolated in the geospatial platform for soil characteristic mapping. It is found that no research is conducted on halophytes of the lake. Studies on soil are also inconsistent and only six common parameters could be identified. Results show that the pH ranged 9.37–7.66, electrical conductivity was 16.1–0.38, moisture 23.37%–1.2%, organic carbon 3.29%–0.15%, organic matter 5.6%–0.2%, and salinity 8.86%–0.72%. Though these results show improved condition as compared to last few years, in long term, the lake is desiccating. During the UN Decade of Ecosystem Restoration (2021–2030), if these causes are not addressed, the ecosystem may completely dry up.Keywords：halophytes;inland lakes;saline wetlands;soil;geospatial mapping;interpolation14|0|1Updated：2024-10-14
- Abstract：The prokaryotic cell storage compound ploy-β-hydroxybutyrate (PHB) has been considered as prebiotics that can be applied in aquaculture. In this paper, the dietary effect of a PHB-accumulating Halomonas strain (HM·PHB) identified from our previous work were studied in Artemia under gnotobiotic and xenic culture conditions, in comparison of Halomonas without PHB accumulation (HM) and microalgae Isochrysis (ISO) feeding. Under gnotobiotic condition, both HM·PHB and HM served as sole food supporting Artemia survival. Although both HM·PHB and HM feeding had no significant difference on Artemia survival percentage (P>0.05), HM·PHB significantly improved their resistance against Vibrio anguillarum challenge (P<0.05). Mass Artemia culture were further performed in xenic condition. Compared to ISO, HM·PHB feeding protected Artemia against V. anguillarum challenge (P<0.05), and HM·PHB and HM feeding resulted in increased T-AOC, pepsin, T-SOD and CAT activities (P<0.05). High throughput sequencing analysis showed that HM·PHB and HM feeding resulted in a lower Artemia gut microbial diversity (P<0.05), and modified the gut microbial community by remarkably reducing the Vibrio proportion. The outcome of the paper confirmed the beneficial effect of Halomonas-PHB in Artemia culture, which supports the use of Halomonas-PHB in the production of bio-secured live feed Artemia.Keywords：Halomonas-ploy-β-hydroxybutyrate (Halomonas-PHB);Artemia;pathogen resistance;gut microbiota15|0|0Updated：2024-10-14
- Abstract：Brine shrimp Artemia franciscana provide food for many migrating and staging birds that spend summer and fall on Great Salt Lake, Utah, USA. Artemia produce live young and cysts (hard-walled eggs); these cysts are commercially harvested on Great Salt Lake and support a large industry in Utah. It is unclear the impact that millions of hungry birds have on the Artemia population in the lake. To help assess that, this study evaluated cyst viability (percentage of cysts that contain an embryo) and hatchability (percent of cysts that hatch) from cysts that had passed through the digestive tract of eared grebes Podiceps nigricollis and cysts obtained directly from Great Salt Lake at the same site where each grebe was collected. Hatchability was significantly higher for cysts collected from the water column (19%) than from the stomach (0.3%) or intestines (3%) of eared grebes. Viability also was significantly different for cysts collected from the water column (29%), stomach (0.7%), and intestines (5%). These results indicate that eared grebes nutritionally benefit from eating cysts and that they may be an important food source for grebes in late fall after the adult population of Artemia dies off due to the water becoming too cold. Also, enough cysts survive their passage through the digestive system that grebes can vector hatchable cysts to other waterbodies.Keywords：Artemia;dispersal;eared grebes;hatchability;invasive species;Great Salt Lake;salty lakes;viability14|0|0Updated：2024-10-14
- Abstract：To explore pharmaceutical actinobacteria from salty environments in Siberia, 8 soil samples were collected from different depths of Gudzhirganskoe saline lake, the Republic of Buryatia, Russia. Totally, 635 actinobacterial strains affiliated with 21 genera in 12 families of 7 orders were obtained by culture-dependent approaches. The predominant genus was Streptomyces (74.5%), followed by Microbacterium (4.9%), Agromyces (3.5%), Nocardiopsis (3.0%), and Kitasatospora (2.5%). Seven strains showed relatively low 16S rRNA similarities (<98.65%) with validly described species. Seventy-seven strains were selected as representatives to evaluate their antimicrobial activities and underlying mechanisms by paper-disk diffusion method and a double fluorescent protein reporter system (pDualrep2), respectively. Streptomyces sp. S6b3-1 was highlighted due to its strong inhibitory activities against Gram-positive bacteria and underlying antibacterial mechanism by inducing the SOS response in the reporter system. LG-1, (R)-6-[1-(benzoyloxy) ethyl]-phenazine-1-carboxylic acid, an analogue of saphenamycin was finally isolated from the culture broth of Streptomyces strain. This study preliminarily explored the actinobacterial diversity of soil samples collected in the highly alkaline and saline lake Gudzhirganskoe by culture-dependent approach and their capacity to produce antibiotics for the first time, which revealed that it deserves to make more efforts to discover new actinobacterial species and potential new antibiotics from the saline lake in Eastern Siberia.Keywords：Gudzhirganskoe saline lake;actinobacteria;diversity;antimicrobial activities;phenazine antibiotic16|0|1Updated：2024-10-14
- Abstract：The long-term data (1996–2021) on the summer abundances of the dominant zooplankton species (copepod Arctodiaptomus salinus (Daday, 1885), rotifers Brachionus plicatilis (Müller, 1786) and Hexarthra sp.) in saline Lake Shira were used to analyze the response of zooplankton to air temperature and a change in the circulation regime of the lake: breakdown and reestablishment of meromixis. All groups of zooplankton responded to prolonged summer elevated temperatures by increasing their abundance. During the breakdown of the stable stratification of Lake Shira (2015–2016), zooplankton abundance increased on average by a factor of two and amounted to 9×105 inds./m2 in the water column for copepods. That increase coincided with similar responses of other components of the lake’s mixolimnion ecosystem, whose biomasses increased approximately two-fold during that period. After the reestablishment of the meromixis, the abundance of zooplankton decreased to previous values. Thus, the abundance of zooplankton is largely determined by weather (the effect of temperature) and ecological factors (mixing regime).Keywords：meromictic lake;zooplankton;copepods;rotifers;meromixis breakdown14|0|1Updated：2024-10-14
- Abstract：Saline and hypersaline wetlands account for almost half of the volume of inland water globally. They provide pivotal habitat for a vast range of species, including crucial ecosystem services for humans such as carbon sink storage and extractive resource reservoirs. Despite their importance, effective ecological assessment is in its infancy compared to current conventional surveys carried out in freshwater ecosystems. The integration of environmental DNA (eDNA) analysis and traditional techniques has the potential to transform biomonitoring processes, particularly in remote and understudied saline environments. In this context, this preliminary study aims to explore the potential of eDNA coupled with conventional approaches by targeting five hypersaline lakes at Rottnest Island (Wadjemup) in Western Australia. We focused on the invertebrate community, a widely accepted key ecological indicator to assess the conservational status in rivers and lakes. The combination of metabarcoding with morphology-based taxonomic analysis described 16 taxa belonging to the orders Anostraca, Diptera, Isopoda, and Coleoptera. DNA-based diversity assessment revealed more taxa at higher taxonomic resolution than the morphology-based taxonomic analysis. However, certain taxa (i.e., Ephydridae, Stratyiomidae, Ceratopogonidae) were only identified via net surveying. Overall, our results indicate that great potential resides in combining conventional net-based surveys with novel eDNA approaches in saline and hypersaline lakes. Indeed, urgent and effective conservational frameworks are required to contrast the enormous pressure that these ecosystems are increasingly facing. Further investigations at larger spatial-temporal scales will allow consolidation of robust, reliable, and affordable biomonitoring frameworks in the underexplored world of saline wetlands.Keywords：macroinvertebrate;hypersaline;environmental DNA (eDNA);conservation;ecological survey;community composition14|0|1Updated：2024-10-14
- Abstract：Cladocera are filter feeders abundant in freshwaters, which consume phytoplankton particles in wide size and taxonomic ranges. The ability of cladocerans to control phytoplankton abundance by grazing is determined by various factors including the characteristics of phytoplankton. Freshwater salinization may reduce the strength of top-down grazing control of phytoplankton because of the detrimental effects of salinity on the grazing intensity of zooplankters. We performed grazing experiments with two species of Cladocera of different body lengths to test their ability to graze on phytoplankton in natural waters differing in salinity and size and taxonomic composition of food particles. Grazing experiments demonstrated that the grazing rate was mostly controlled by the abundance of phytoplankton in the medium. The grazing rate was reduced at salinity ca. above 3 g/L of NaCl in the medium. The lower grazing rate was observed in the medium with larger phytoplankton particles. Both species predominantly consumed phytoplankton particles with a diameter of 6–12 µm, which may shift the size distribution of phytoplankton towards a larger average diameter of particles. The taxon-specific feeding was also observed, as both species predominantly consumed diatom algae. Thus, we found that because of grazing, the size and taxonomic characteristics of phytoplankton are shifted towards a less edible community. The detrimental effect of elevated salinity on grazing rate supports growing concern about freshwater salinization negatively affecting water quality, particularly reducing top-down grazing control of phytoplankton.Keywords：selective feeding;Daphnia;Moina;top-down control;phytoplankton;salinity14|0|1Updated：2024-10-14
- Abstract：Sergei Winogradsky illuminated revolutionary concepts and produced a tool to visualize complex microbial communities and their metabolisms over time: columns displaying aquatic consortia with variety of niches. We worked with museums in Utah to create Winogradsky columns that would highlight aesthetic properties of the Great Salt Lake (GSL) ecosystem, which has a salinity gradient from the freshwater wetlands to salt saturation. One column, constructed using haloarchaea-rich hypersaline brine and oolitic sand of the lake’s north arm, was enriched with nutrients, and resulted in the desired pink hue over time. After a seven-year maturation period, we examined the microbial taxa present in the water through 16S/18S rRNA and Internal Transcribed Spacer (ITS) gene sequencing. A pigment analysis revealed an abundance of bacteriochlorophyll a. The presence of this pigment coupled with the DNA sequencing results, suggest that the haloarchaea that dominate the GSL brine, were not responsible for the pink coloration, but instead Gammaproteobacteria, especially Halorhodospira species. Among the eukaryotes, the lack of phytoplankton and the abundance of fungi were noteworthy observations. These data likely relate to the reduction of oxygen in a non-aerated sealed system over time. Our second exhibit had the goal of educating museum goers about the varying salinities of Great Salt Lake. Here we employed three distinct columns of water and sediment from this salinity gradient. Observations of these columns overtime gave us information about invertebrate communities in addition to the microbial consortia. Both installations taught us about comparing an artificial environment in a museum setting to the natural ecosystem. Taken together, we present the data collected and lessons learned from using Winogradsky columns in public spaces for teaching about an important saline lake.Keywords：Great Salt Lake;Winogradsky;halophiles;extreme environment;museum exhibit15|1|0Updated：2024-10-14
Special Section on Salt Lake Research
- Abstract：The South China Sea (SCS) is the largest marginal sea in the Northwest Pacific Ocean, and it encounters frequent typhoons. The atmosphere and ocean will create significant thermal and dynamic responses during the intense disturbance caused by typhoons. However, these responses have not been thoroughly investigated owing to the complicated marine environment. According to the satellite data, the SCS Basin was observed to have a strong sea surface temperature (SST) response to Typhoon Mangkhut, resulting in widespread SST cooling. A coupled model was used to investigate the atmospheric and oceanic responses to Typhoon Mangkhut. Best-track data, satellite SST, and ARGO measurements show that the coupled WRF-CROCO simulation displays better track, intensity, SST, temperature, and salinity profiles than those of the WRF-only simulation. Results show that the typhoon induced rightward intensifications in wind speed, ocean current, and SST. The following are some remarkable atmosphere and ocean responses: (1) the SST below the inner-core region is cooled by 1 °C, resulting in a 37%–44% decrease in wet enthalpy, and the central pressure is increased by ~9 hPa. Therefore, the changes in SST below the inner-core region of the SCS Basin have a significant impact on air-sea fluxes under high-wind conditions; (2) the ocean boundary layer analysis shows that near-inertial oscillations on the right side of the typhoon track and a strong inertial current up to ~2.28 m/s in the upper ocean were observed, which resonated with the local wind and flow field on the right side and induced strong SST cooling; (3) a decrease in SST decreased the moist static energy of the typhoon boundary layer, thereby weakening the typhoon’s intensity. The difference in equivalent potential temperature and sea surface pressure have a good correlation, indicating that the influence of moist static energy on typhoon intensity cannot be overlooked.Keywords：Super Typhoon Mangkhut;coupled ocean-atmosphere model;wet enthalpy;inertial current14|0|0Updated：2024-10-14
- Abstract：There is a vast upwelling area induced by the southeast monsoon in the waters off South Java, making the region an important fishing ground. Climate events can affect the variation of upwelling, but oceanographers have different understandings on the extent to which climate events control upwelling in this area, which leads to a lack of basis for studies on the evaluation and mechanisms of the variability of fishery resources in the region. The correlation between environmental parameters, including surface temperature (SST), chlorophyll-a (Chl-a) concentration, and climate event indices in South Java from 2003 to 2020 was analyzed. Results show that the Indian Ocean Dipole (IOD) has a greater influence on the interannual variability of upwelling intensity than ENSO. During the IOD, variations in equatorial latitudinal winds excite different types of Kelvin waves that anomalously deepen or shallow the thermocline, which is the main cause of anomalous variations in upwelling, independent of variations in the local wind field. A correlation between the interannual variability in upwelling and the annual catches was revealed, showing that climatic events indirectly affect fishery resources through upwelling effects. During positive IOD/El Niño periods, strong upwelling delivers more nutrients to the surface layer, which favors fish growth and reproduction, resulting in higher annual catches. A negative IOD/La Niña, on the other hand, leads to weaker upwelling and fewer nutrients into the surface waters. Fish tend to move in deeper waters, making traditional fishing methods less efficient and consequently lower annual catches.Keywords：South Java;El Niño/La Niña-Southern Oscillation (ENSO);Indian Ocean Dipole (IOD);fishery resources;upwelling16|0|0Updated：2024-10-14
- Abstract：Colored dissolved organic matter (CDOM) is an important optically active substance in marine environment. Its biochemical conservatism makes it an important indicator to offshore pollution process. Monitoring the content, composition, and diffusion process of CDOM is a good approach to analyze the terrestrial input, optical properties, and ecological environment of offshore areas. The spatiotemporal characteristics of CDOM around the Leizhou Peninsula were analyzed based on field observation data collected in the autumn 2020 and spring 2021, and an empirical inversion model of the ag(355) (absorption coefficient at 355 nm) and spectral slope (Sg) (g stands for gelbstoff/gilvin, which is called CDOM) based on Sentinel-3A ocean and land color instrument (OLCI) images was constructed. The results show (1) the order of average ag(355) value around the Leizhou Peninsula was east coast (0.503/m)>Qiongzhou Strait (0.502/m)>west coast (0.365/m); (2) the best band combinations of CDOM inversion in spring and autumn were (B4+B11)/B3 and (B7–B1)/B6 (B stands for the band of spectral images), and the final inversion results are close to the measured results, indicating that the model has good accuracy; (3) the Sg value of the CDOM absorption spectrum was fitted to the hyperbolic-exponential model. The fitting accuracy of the model was higher than those of the exponential model and the hyperbolic model, and the best Sg inversion model was constructed by selecting Sg(275–295) and Sg(250–295) in spring and autumn; (4) the spatial distributions of ag(355) and Sg were inverted, and CDOM in the waters around the Leizhou Peninsula originated from terrestrial organic matter carried by coastal aquaculture zones and runoff in the northeast Zhanjiang and the northern Beibu Gulf.Keywords：colored dissolved organic matter (CDOM);ocean and land color instrument (OLCI);spectral slope;hyperbolic-exponential model;inversion19|0|1Updated：2024-10-14
Physics
- Abstract：The change in the ecological environment in the arid core area is a critical issue in the context of global warming. To study the paleoclimate evolution, precise identification of minerals deposited in Asia’s arid hinterland, Lop Nur Salt Lake, NW China was conducted. The hyperspectral data of the salt crust was sampled to identify the species and content of sedimentary minerals, and the multispectral photos were used to reconstruct the salt crust morphology using the unmanned aerial vehicles platform. The SUnSAL (sparse unmixing by variable splitting and augmented Lagrangian) method was employed to inverse the sedimentary mineral components along the shoreline. The heterogeneity of salt and clay minerals in bright and dark ear-shaped strips was evaluated. The paleoclimatic environment associated with salt lake extinction was reconstructed by analyzing paleoclimate records of sediments, spectral reflectance and morphology of the salt crust. Results show that: (1) the variations in the micro-geomorphology of the salt crust are obviously the reason for the formation of bright and dark ear-shaped strips and the differences in the species and relative content of the sedimentary minerals are the microscopic reason. The high ratio of sedimentary salt minerals to clay minerals (RS/C) contributes to the high reflectivity, and the salt crust presents a bright texture. The low RS/C results in the low reflectivity, salt crust presents a dark texture; (2) the bright and dark ear-shaped strips represent warm-arid and cold-humid climates. The shape of the Lop Nur Lake shoreline evolved due to alternating warm-dry and cold-humid paleoclimate changes.Keywords：UAV remote sensing;Lop Nur;sparse spectral unmixing;salt lake;paleoclimate change14|0|0Updated：2024-10-14
- Abstract：With the development of economy, the impact of human activities on ecological environment is increasing, and environmental protection work is important. Trace elements (Co, Ni, Cu, Pb, Zn, Cd, Cr, and Sc) in surface fine-grained sediment samples from the Jiaozhou Bay catchment were selected to evaluate their 2015 environmental background values and the environmental quality. Using statistical analysis, the environmental background values (ranges) of Sc, Co, Ni, Cu, Pb, Zn, Cd, and Cr were calculated, being 13.1 (10.8–15.4), 12.4 (8.6–16.2), 32.0 (22.9–41.2), 29.6 (13.5–64.9), 24.1 (13.0–44.6), 77.6 (38.5–156.5), 0.07 (0.02–0.20), and 82.5 (66.5–104.0) mg/kg, respectively. The enrichment factor, contamination factor, and pollution load index were used to evaluate the pollution status of the Jiaozhou Bay catchment. The environmental background values of most elements are higher than those of the upper continental crust and lower than those of global shale. At present, the pollution in the eastern Jiaozhou Bay is much higher than that in the western part. The results shall be helpful for future management for trace element pollution monitoring in the Jiaozhou Bay catchment.Keywords：sediments;environmental background values;environmental assessment;Contamination;Jiaozhou Bay12|0|0Updated：2024-10-14
Geology
- Abstract：Upper Circumpolar Deep Water (UCDW) and North Pacific Deep Water (NPDW) coexist in the upper deep layer (i.e., with a 1.2–2.0-℃ potential temperature range and a 2 000–4 100-dbar pressure range) of the Eastern Philippine Sea. They have similar properties in potential temperature and salinity, while have a significant difference in dissolved silicate. Based on the repeated observations along a 137°E transect from the World Ocean Database (WOD18), this study revealed the interannual variability of dissolved silicate in the upper deep layer of the Eastern Philippine Sea. Dissolved silicate increased in 1995, 1996, 2005, 2006, and 2007, and decreased in 1997, 2000, 2001, 2002, and 2004. Composition analysis showed that the large difference between positive and negative dissolved silicate anomalies occurred mainly at ~15°N and north of 25°N, with the concentration reaching 4.25 μmol/g. Further analysis indicated that the interannual dissolved silicate variability was related to the zonal current variation in the upper deep layer. The relatively strong (weak) westward current transport increased (decreased) NPDW to the Eastern Philippine Sea, thereby resulting in increased (decreased) dissolved silicate.Keywords：interannual variability;North Pacific deep water;upper deep layer;dissolved silicate;zonal velocity variability12|0|0Updated：2024-10-14
- Abstract：A five-component weighted average partial least squares (WA-PLS) calibration model was developed by analysing diatom assemblages in 34 surface sediment samples (collected in 2015) from the Changjiang River estuary (CRE) and its adjacent areas to infer dissolved inorganic nitrogen (DIN) concentrations. Eighteen additional sets of surface sediment diatoms and corresponding upper water DIN data (collected in 2012) were used to evaluate the accuracy of the model, and the relationship between observed and diatom-inferred DIN (DI-DIN) values (R2=0.85) illustrated the strong performance of the transfer function, indicating that precise reconstructions of former DIN are possible. The diatom-DIN transfer function was applied to the diatom record from a sediment core DH8-2 (1962‒2012) collected in the Fujian-Zhejiang area south of the CRE. The reconstruction based on the DI-DIN model showed a significant DIN increase from 1962–2012, reflecting the influence of human activities on the very large increase in eutrophication. Three distinct periods can be seen from the changes in DIN and diatom taxa. In the 1962–1972 period, the DIN content was relatively low, with an average of 5.94 μmol/L, and more than 80% of the diatom species identified were benthic taxa. In the 1972–2004 period, as the impact of human activities intensified, large nutrient inputs caused the DIN content to increase, with an average of 8.25 μmol/L. The nutrient inputs also caused a significant change in the nutrient components and a distinct increase in small planktonic taxa. In the 2004–2012 period, the DIN content continued to rise, fluctuating at approximately 10 μmol/L. A continuous increase in the frequency of planktonic taxa (up to 65.48%) indicated that eutrophication was further intensified, which was confirmed by the transformation from diatom-induced red tide to dinoflagellate-induced red tide during this period.Keywords：Changjiang River estuary;dissolved inorganic nitrogen (DIN) reconstruction;diatoms;transfer function15|0|0Updated：2024-10-14
Chemistry
- Abstract：As an important spawning ground for large yellow croaker Larimichthys crocea, Sansha Bay, South China Sea has been a research hotspot. However, studies on the influence of the bacterioplankton community and assessments of its seasonal succession of bacterioplankton in different sea areas in Sansha Bay are still limited. To address the issue, we use 16S rRNA gene amplicon sequencing and functional prediction to investigate the spatial-temporal dynamics of the bacterioplankton community in three distinct areas, i.e., Breeding Area (BA), Yantian Harbor (YH), and Bay Margin (BM) of Sansha Bay. Results show that the structure of the bacterioplankton community in Sansha Bay had a significant seasonal succession. Moreover, the representative zero-radius Operation Taxon Units in different seasons were significantly different among the three selected sea areas. Specifically, during the breeding season, bacterioplankton communities in BA were characterized by compound-degrading bacteria, such as Rhodococcus and Owenweeksia, while in YH and BM, animal parasites or symbionts such as Vibrio and Arcobacter were dominant. Furthermore, the redundancy analysis and Spearman correlation analysis further explained that water temperature, dissolved oxygen, and ammonia nitrogen were the main environmental factors responsible for the difference. In addition, the bioindicator functions screened by Functional Annotation of Prokaryotic Taxa and random forest machine learning mainly relied on compound degradation, nitrite oxidation, and photoheterotrophy. The compound-degradation-corresponded bacterioplankton genera such as Rhodococcus had relatively higher abundance in BM, while Nitrospina corresponding to nitrite oxidation tended to be abundant in YH and BA. Based on the spatial and temporal variation in the composition and function of bacterioplankton, our findings provide a basis for understanding the theory of bacterioplankton community structure in the inner-bay habitat of the large yellow croaker in Sansha Bay.Keywords：microbial ecology;bacterioplankton;large yellow croaker;breeding area;functional prediction14|0|0Updated：2024-10-14
- Abstract：In recent years, herbicide sulfometuron-methyl (SM) has been used to kill the invasive plant Spartina alterniflora in some coastal areas of China, which may lead to the toxic effects on non-target marine organisms. The 96-h median effective concentrations (96-h EC50) of SM on six species of marine microalgae were measured in growth inhibition tests, and were then compared with other published toxicity data, based on which a method of species sensitivity distribution (SSD) was built to estimate the hazardous concentration of SM for 5% of species (HC5) and potentially affected fraction (PAF) for a certain concentration. Results indicate that SM exhibited a high toxicity to two species of green algae (Chlorella pacifica and Dunaliella salina) with a 96-h EC50 of 0.11 and 0.13 mg/L respectively, had a medium toxicity to two species of golden algae (Diacronema viridis and Isochrysis galbana) with a 96-h EC50 of 14.24 and 21.48 mg/L respectively, and showed a low toxicity to two species of diatoms (Skeletonema costatum and Phaeodactylum tricornutum) with a 96-h EC50 of 148.99 and >100 mg/L, respectively. The estimated values of HC5 and the predicted no-effect concentrations (PNEC) for SM were 0.077 and 0.015 mg/L, respectively. According to the current dosage for killing S. alterniflora in tidal flats in Fujian Province, China, SM entering the sea by spraying might cause the acute injury or death of 14% of marine species. This hazard could last for about a month for those sensitive species. Therefore, on the premise of inhibiting the growth of this invasive plant, the dosage of SM should be reduced as much as possible to avoid severe damage to the marine ecosystem. The results provide a valuable information for marine ecological risk assessment on SM and for marine environmental management.Keywords：sulfometuron-methyl (SM);microalgae;acute toxicity;species sensitivity distribution (SSD);marine ecological risk14|0|2Updated：2024-10-14
- Abstract：The research on the biological ecology of the Prydz Bay-Amery Ice Shelf in East Antarctica is inadequate under the increasing threat from climate change, especially for Antarctic fish and krill. The Dynamic Bioclimatic Envelope Model (DBEM) has been widely used in predicting the variation of species distribution and abundance in ocean and land under climate change; it can quantify the spatiotemporal changes of multi population under different climate emission scenarios by identifying the environmental preferences of species. The species richness and geographical pattern of six Antarctic representative species around Prydz Bay-Amery ice shelf were studied under RCP 8.5 and RCP 2.6 emission scenarios from 1970 to 2060 using Geophysical Fluid Dynamics Laboratory (GFDL), Institut Pierre Simon Laplace (IPSL), and Max Planck Institute (MPI) earth system models. The results showed that the species richness decreased as a whole, and the latitude gradient moved to the pole. The reason is that ocean warming, sea ice melting, and human activities accelerate the distribution changes of species biogeographical pattern, and the habitat range of krill, silverfish, and other organisms is gradually limited, which further leads to the change of species composition and the decrease of biomass. It is obvious that priority should be given to Prydz Bay-Amery ice shelf in the planning of Marine Protected Areas (MPAs) in East Antarctica.Keywords：climate change;species richness;biogeographic pattern;marine protected areas;Prydz Bay-Amery Ice Shelf16|0|0Updated：2024-10-14
- Abstract：We used the Integrated Biological Responses version 2 (IBRv2) method to evaluate the biological effects of heavy metals in the sediments in Laizhou Bay, China on the benthic goby Acanthogobius ommaturus. In December 2018, gobies and sediments were collected from 15 stations. We measured the activities of defense enzymes and the contents of malondialdehyde (MDA) and metallothionein (MT) in the goby liver as well as the levels of heavy metals in the sediments and goby muscle tissue. Most of the heavy metal concentrations in sediment at each station were below the Class I criteria set by Chinese Standards for Marine Sediment Quality, and the Håkanson ecological risk index suggested low risk for the heavy metals. We found that A. ommaturus could effectively accumulate mercury, cadmium, arsenic, and zinc and that the contents of MT and MDA and the activities of glutathione peroxidase and glutathione reductase were suitable biomarkers of heavy metal pollution in this species. The IBRv2 method integrated these four biomarkers and discriminated stations according to heavy metal pollution. Higher IBRv2 values suggested more adverse effects in gobies, corroborating more serious heavy metal contamination. The stations with high IBRv2 values and high contents of heavy metals were mainly distributed in the west and northeast parts of the bay. These results show that the IBRv2 approach is a feasible strategy for assessing heavy metal pollution through biological response and biological status and that it can be implemented for environmental monitoring in Laizhou Bay.Keywords：integrated biomarker responses;heavy metal;assessment;goby Acanthogobius ommaturus;Laizhou Bay12|0|1Updated：2024-10-14
Ecology
- Abstract：The microalga Phaeocystis globosa is recognized as a harmful alga and also one of the few keystone phytoplankton genera that shape the structure and function of marine ecosystems. P. globosa possess a complex polymorphic life cycle, exhibiting phase alternation between free-living cells of approximately 3–6 μm in diameter and gelatinous colonies (palmelloid stage) reaching several millimeters. The knowledge on the factors that induced the morphological transition of P. globosa in the last two decades was reviewed. Emphasis is given to infochemicals, an additional biological factor induced by predator, with the attempt to reveal a relevant mechanism of induced morphological defense.Keywords：Phaeocystis globosa;polymorphisms;harmful algal blooms;defense strategies;infochemical16|0|0Updated：2024-10-14
- Abstract：Lipidomics approach by UPLC-Q-Exactive-MS was used for the identification, quantification, comparison, and characterization of sphingolipids in virus infected marine Emiliania huxleyi BOF92 cells. The results show that 16 significantly changed sphingolipids (including Cer, CerG1, and SPHm) were identified during viral infection. Our data confirmed previously recognized facts that viral infection led to a shift toward virus-specific sphingolipids, which is consistent with the down-regulation of genes involved in the host de novo sphingolipid biosynthesis. Moreover, we revealed the upregulation of virus-encoded homologous genes participating in de novo sphingolipids biosynthesis and virus-specific hydroxylated long chain bases (LCBs) as phytoCer, suggesting the competitive inhibition of host sphingolipid synthesis to produce the required building blocks for viral production, replication, and assembly. Additionally, Cer 40꞉1;2, Cer 40꞉2;2 isomer, and CerG1 39꞉0;2, Cer 39꞉0;2 as novel metabolite markers might indicate the general dysfunctions in E. huxleyi in response to viral infection. Our results show that viral infection led to a profound remodeling of host sphingolipidome, by which viruses depend on the hijacking of host sphingolipid metabolism to support the viral life cycle.Keywords：Emiliania huxleyi;Coccolithovirus;UPLC-Q-exactive-MS;sphingolipid metabolism;biomarkers15|0|0Updated：2024-10-14
- Abstract：Dunaliella salina is a classic halophilic alga. However, its molecular mechanisms in response to high salinity at the post transcriptional level remain unknown. A unique halophilic alga strain, DS-CN1, was screened from four D. salina strains via cell biological, physiological, and biochemical methods. High-throughput sequencing of small RNAs (sRNAs) of DS-CN1 in culture medium containing 3.42-mol/L NaCl (SS group) or 0.05-mol/L NaCl (CO group) was performed on the BGISEQ-500 platform. The annotation and sequences of D. salina sRNAs were profiled. Altogether, 44 novel salt stress-responsive microRNAs (miRNAs) with a relatively high C content, with the majority of them being 24 nt in length, were identified and characterized in DS-CN1. Twenty-one differentially expressed miRNAs (DEMs) in SS and CO were screened via bioinformatic analysis. A total of 319 putative salt stress-related genes targeted (104 overlapping genes) by novel miRNAs in this alga were screened based on our previous transcriptome sequencing research. Furthermore, these target genes were classified and enriched by GO and KEGG pathway analysis. Moreover, 5 novel DEMs (dsa-mir3, dsa-mir16, dsa-mir17, and dsa-mir26 were significantly upregulated, and dsa-mir40 was significantly downregulated) and their corresponding 10 target genes involved in the 6 significantly enriched metabolic pathways were verified by quantitative real-time PCR. Next, their regulatory relationships were comprehensively analyzed. Lastly, a unique salt stress response metabolic network was constructed based on the novel DEM-target gene pairs. Taken together, our results suggest that 44 novel salt stress-responsive microRNAs were identified, and 4 of them might play important roles in D. salina upon salinity stress and contribute to clarify its distinctive halophilic feature. Our study will shed light on the regulatory mechanisms of salt stress responses.Keywords：Dunaliella salina;salt stress response;small RNA (sRNAs) sequencing;microRNA (miRNAs)18|0|0Updated：2024-10-14
- Abstract：Vitellogenesis is the main event of oocyte growth in oviparous animals, which is mainly manifested by the accumulation of vitellogenin (VTG). The accumulation of vitellogenin depends mainly on the absorption of exogenous vitellogenin, which enters oocyte through endocytosis mediated by its receptor (VGR). We investigated the expression and localization of VTG and VGR during gonad development of Pampus argenteus. The qPCR results show that vtgs were not expressed in male fish, but in the ovary and liver of female fish; the expression levels went up at first and then down. The expression levels of vgr in the testis were low and only 1%–3% of that in ovary. ELISA results show that during the ovarian development of P. argenteus, VTG in liver, serum, and ovary all showed a trend from increasing to decreasing. However, VTG in liver peaked in Stage Ⅳ, and in serum and ovary peaked in Stage V, reflecting changes in the characteristics of VTG in the liver (synthesis), blood (transport), and ovaries (accumulation). During gonad development, VGR in the ovaries first increased and then decreased, reaching a peak in Stage V, in contrast to vgr mRNA expression. The VGR content in the testis was extremely low and stable, consistent with vgr mRNA. Immunohistochemistry results show that the location and intensity of VTG and VGR positive signals were synchronized with the changes of their protein content, which revealed that VTG was mainly synthesized in the liver cytoplasm, secreted into the blood, and transported to ovary in Stage Ⅲ. VGR is highly expressed in oocytes in Stage Ⅱ. In Stage Ⅲ, a large amount of VTG reaches the ovary, when VGR begins to translate and is subsequently transported to the plasma membrane of the oocyte. Therefore, the positive signal of VGR was stronger near the plasma membrane of oocytes in Stages Ⅰ and Ⅱ. By using qPCR, ELISA, and immunohistochemistry, the synthesis, transport, and accumulation of vitellogenin were elucidated and the mechanism of its endocytosis on egg membrane mediated by VTG during the development of P. argenteus was revealed preliminarily.Keywords：Pampus argenteus;vitellogenin (Vtg);vitellogenin receptor (VGR);vitellogenesis14|0|0Updated：2024-10-14
- Abstract：The sea star Asterias amurensis is widely viewed as a severe “marine pest” because of its broad feeding habits. Over the past few decades, A. amurensis undergoes massive and sporadic population outbreaks worldwide, causing extensive economic and ecological losses to the local aquaculture industry and marine ecosystem. Understanding the genetic diversity and population structure of A. amurensis can provide vital information for resource management. By analyzing the polymorphism of the mitochondrial cytochrome C oxidase subunit I (COI) gene and ten simple sequence repeat (SSR) microsatellites markers, the genetic diversity and population structure of A. amurensis of four populations along the northern coast of China was uncovered. A total of 36 haplotypes were identified, and a main haplotype was found in four populations. The Qingdao (QD) population displayed the highest genetic diversity among all the populations. The AMOVA and pairwise Fst showed that there was small but statistically significant population differentiation among the four populations, especially between QD and Weihai (WH). Moreover, the principal component analysis (PCA) and admixture analysis showed that several individuals in Yantai (YT) and Dalian (DL) had little genetic association with other individuals. Overall, this study provided useful information of the genetic diversity and population structure of A. amurensis and will contribute to the resource management of A. amurensis in China.Keywords：Asterias amurensis;cytochrome C oxidase subunit I (COI);simple sequence repeat (SSR);population structure;China seas16|0|0Updated：2024-10-14
Biology
- Abstract：In the East China Sea (ECS), chub mackerel Scomber japonicus constitutes an important coastal-pelagic fishery resource that is mainly exploited by Chinese, Japanese, and Korean light-purse seine fisheries. Because the early life history of chub mackerel plays a significant role in its recruitment, we developed an individual-based model to study the distribution, growth, and survival rate of chub mackerel larvae and juveniles in the ECS to improve our understanding of the chub mackerel population structure and recruitment. Our results show that as body length rapidly increases, the swimming capacity of chub mackerel larvae and juveniles improves quickly, and their spatial distribution depends more on their habitat conditions than the ocean currents. Correspondingly, the juveniles from the central and southern ECS spawning ground are scarcely recruited into the Japan/East Sea (JES) or the western Pacific Ocean, but a significant proportion of juveniles from the northern ECS spawning ground still enter the JES and there are exchanges between the stocks in the ECS and JES. Thus, it seems more reasonable to assess and manage the chub mackerels in the ECS and JES as a stock. The water temperature and ocean primary production in the ECS are two important factors influencing the chub mackerel habitat conditions and their spatial and temporal distribution are significantly different as the spawning time changes. Therefore, the spawning time and location play an important role in the growth and survival rate of the larvae and juveniles. Generally, when chub mackerel spawns at the southern ECS spawning ground in March, the larva and juvenile growth and survival rate is relatively high; as spawning time moves forward, higher growth and survival rates would be expected for the chub mackerel spawned coastward or northward. For specific spawning sites, early or delayed spawning will reduce the survival rate.Keywords：East China Sea (ECS);Scomber japonicus;individual-based model;early life history17|0|1Updated：2024-10-14
- Abstract：Japanese Spanish mackerel Scomberomorus niphonius is a pelagic, neritic species that occurs in the Yellow Sea in high commercial value. The spawning period of this fast-growing species is controlled by water temperature. Based on microstructural analysis of otoliths from 145 young-of-the-year (YoY) S. niphonius collected by trawl in 2017, 2018, and 2020, and the temporal variation in the spawning period in the northern Yellow Sea, and its relationship to water temperature were examined. We found that the spawning lasted from late April to late June but differed in year: in 2017 it occurred from April 23 to June 1 and peaked in early May, in 2018 it extended later from May 7 to June 29, and in 2020 from May 6 to June 22 and peaked later from late May to mid-June. The highest temperature in 2017 corresponds with the earliest end of the spawning period and a lower growing degree-day (GDD, °C·day) of 383 °C·day. In 2018, slower warming corresponds with a longer spawning period, and a GDD spawning period of 506 °C·day. Rapid warming in late 2020 corresponds with a spawning peak, and a GDD spawning temperature of 448 °C·day. Despite differences in spawning period, the water temperature when spawning commenced was 10–12 °C. Therefore, water temperature is the major determinant of the spawning period, affecting both the starting and the ending of spawning. This study improved our understanding of the spawning dynamics and environmental adaptation of S. niphonius, and how these might change in environments subject to increased warming.Keywords：otolith microstructure;Scomberomorus niphonius;spawning period;Yellow Sea;water temperature14|0|0Updated：2024-10-14
Aquaculture and Fisheries
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