Issue Ebook
cover story
Latest Issue
Volume 38 ， Issue 6 ， 2020
-
- Abstract：Based on initial errors of sea temperature in the tropical Indian Ocean that are most likely to induce spring predictability barrier (SPB) for the El Niño prediction, the sensitive area of sea temperature in the tropical Indian Ocean for El Niño prediction starting from January is identified using the CESM1.0.3 (Community Earth System Model), a fully coupled global climate model. The sensitive area locates mainly in the subsurface of eastern Indian Ocean. The effectiveness of applying targeted observation in the sensitive area is also evaluated in an attempt to improve the El Niño prediction skill. The results of sensitivity experiments indicate that if initial errors exist only in the tropical Indian Ocean, applying targeted observation in the sensitive area in the Indian Ocean can significantly improve the El Niño prediction. In particular, for SPB-related El Niño events, when initial errors of sea temperature exist both in the tropical Indian Ocean and the Pacific Ocean, which is much closer to the realistic predictions, if targeted observations are conducted in the sensitive area of tropical Pacific, the prediction skills of SPB-related El Niño events can be improved by 20.3% in general. Moreover, if targeted observations are conducted in the sensitive area of tropical Indian Ocean in addition, the improvement of prediction skill can be increased by 25.2%. Considering the volume of sensitive area in the tropical Indian Ocean is about 1/3 of that in the tropical Pacific Ocean, the prediction skill improvement per cubic kilometer in the sensitive area of tropical Indian Ocean is competitive to that of the tropical Pacific Ocean. Additional to the sensitive area of the tropical Pacific Ocean, sensitive area of the tropical Indian Ocean is also a very effective and cost-saving area for the application of targeted observations to improve El Niño forecast skills.Keywords：tropical Indian Ocean;El Niño prediction;sensitive area;targeted observation8|0|4Updated：2023-04-27
- Abstract：We investigated the effects of monsoon onset vortex (MOV) on the mixed layer heat budget in the Bay of Bengal (BOB) in spring 2003 using the reanalysis datasets. The results suggest that the solar radiation flux penetrating the mixed layer and the existence of barrier layer are both able to modulate the effects of MOV on the evolution of sea surface temperature (SST) in the BOB. Prior to the formation of BOB MOV, the local SST raised quickly due to mass of solar radiation reaching the sea surface under the clear-sky condition. Meanwhile, since the mixed layer was shallow before the onset of the Asian summer monsoon (ASM), some solar radiation flux could penetrate to directly heat the deeper water, which partly offset the warming effect of shortwave radiation. On the other hand, the in-situ SST started to cool due to the upwelling of cold water when the MOV generated over the BOB, along with the rapidly increased surface wind speed and its resultant deeper mixed layer. As the MOV developed and moved northward, the SST tended to decrease remarkably because of the strong upward surface latent heat flux over the BOB ascribed to the wind-evaporation mechanism. However, the MOV-related precipitation brought more fresh water into the upper ocean to produce a thicker barrier layer, whose thermal barrier effect damped the cooling effect of entrainment upwelling on the decrease tendency of the BOB SST. In other words, the thermal barrier effect could slow down the decreasing trend of the BOB SST even after the onset of ASM, which facilitated the further enhancement of the MOV.Keywords：monsoon onset vortex (MOV);Bay of Bengal;air-sea interaction;mixed layer depth;barrier layer thickness;heat budget analysis5|0|1Updated：2023-04-27
- Abstract：Intensity variations of the SE-NW-oriented tropical cyclones (TC) in the East China Sea (ECS) passing over the Kuroshio are studied using multi-year high-resolution sea surface temperature data, the tropical cyclone data, and the global reanalysis dataset. The statistical results show that there are 81 TCs passing over the Kuroshio from the southeast in the East China Sea, over 68 years from 1949 to 2016. In terms of the change of the atmospheric pressure in the center of the TC, there are three categories:31 TCs are intensified, 28 maintain their intensities, and 22 weakened. Significant seasonal differences are presented in the distribution. In the analysis on the intensified TCs, it is found that the TCs in the range where the center translational speed is from 1 m/s to 8 m/s and the distance from the Kuroshio main axis is from 10 km to 75 km are intensified more significantly. The analysis of three specific examples of TCs show that the stronger characteristics of the Kuroshio warm water in the ECS, the greater the intensity increase of such tropical cyclones.Keywords：intensity of typhoons;Kuroshio;East China Sea4|0|1Updated：2023-04-27
- Abstract：The daily regional reanalysis product of the China Ocean Reanalysis (CORA) product was released in website in 2018. Using in situ observational data including Argo profiling floats, drifters, and cruise data, the performance of CORA in the South China Sea in terms of temperature, salinity, current and mixed layer depths is evaluated based on timescale (seasonal and interannual) and spatial distribution characteristics. The CORA temperature, salinity, and mixed layer depth show certain seasonal and interannual variations. In 50-400 m depth in the SCS, the CORA temperature is colder in winter and warmer in summer and autumn. In 0-150 m in the SCS, the CORA salinity is higher in most time of the year. However, in the second half of the year, the salinity is slightly weaker in 100-150 m depth. In most years, the CORA mixed layer depths tend to be shallower, and in season, shallower in winter and deeper in summer. In spatial distribution, the closer the area is to the coast, the greater the CORA errors would be. The CORA temperature is colder in the western side and warmer in the eastern side, resulting in a weaker SCS western boundary current (SCSwbc). In most areas, the CORA mixed layer depths are shallower. In the area close to the coast, the CORA mixed layer depths change rapidly, and the deviations in the mixed layer depths are larger. In the central SCS, the CORA mixed layer depths change slowly, and the deviations in the mixed layer depths are also small.Keywords：China Ocean Reanalysis (CORA);South China Sea (SCS);drifter, Argo;cruise data;evaluation4|0|2Updated：2023-04-27
- Abstract：As in-situ observations are sparse, targeted observations of a specific mesoscale eddy are rare. Therefore, it is difficult to study the three-dimensional structure of moving mesoscale eddies. From April to September 2014, an anticyclonic eddy located at 135°E-155°E, 26°N-42°N was observed using 17 rapidsampling Argo floats, and the spatiotemporal variations in the three-dimensional structure were studied. The results are as follows:(1) the eddy was identified and tracked using satellite altimeter data. It had a lifetime of 269 days and an average radius of 91.5 km. The lifetime of the eddy can be divided into three phases, i.e., the initiation, maturity, and termination phases. The depth of its influence reached 1 000 m; (2) the Argo profiles were divided into seven periods (approximately 20 days in each) for composite analysis, and the composite Argo profiles and CARS2009 (CSIRO Atlas of Regional Seas) climatology data were merged following the data-interpolating variational analysis (DIVA) method to reconstruct the three-dimensional structure. The temperature and salinity anomaly cores of the anticyclonic mesoscale eddy are located from 400 to 600 m. From 800 to 900 m, there is an area of low salinity at the center of the eddy. A high concentration anomaly of dissolved oxygen was located at approximately 250 m; (3) to better understand the features of the eddy and its interaction with the surroundings, we calculated the anomalous velocity of the geostrophic flow and the heat, salt, dissolved oxygen transport anomaly, and discussed the eddy's origin and its adjustments to topography. The maximum heat, salt, and oxygen transport caused by eddy were 9.37×1011 W, 3.08×103 kg/s, and 2.70×102 kg/s, which all occurred during the termination phase. This study highlights the applicability of using Argo floats to understand the three-dimensional structure thermohaline features of eddies in the North Pacific.Keywords：Argo;three-dimensional structure;spatiotemporal variation;dissolved oxygen4|0|6Updated：2023-04-27
- Abstract：The increases of atmospheric carbon dioxide and other greenhouse gases have caused fundamental changes to the physical and biogeochemical properties of the oceans, and it will continue to occur in the foreseeable future. Based on the outputs of nine Earth System Models from the fifth phase of the Coupled Model Intercomparison Project (CMIP5), in this study, we provided a synoptic assessment of future changes in the sea surface temperature (SST), salinity, dissolved oxygen (DO), seawater pH, and marine net primary productivity (NPP) in the coastal China seas over the 21st century. The results show that the mid-high latitude areas of the coastal China seas (East China Seas (ECS), including the Bohai Sea, Yellow Sea, and East China Sea) will be simultaneously exposed to enhanced warming, deoxygenation, acidification, and decreasing NPP as a consequence of increasing greenhouse gas emissions. The magnitudes of the changes will increase as the greenhouse gas concentrations increase. Under the high emission scenario (Representative Concentration Pathway 8.5), the ECS will experience an SST increase of 3.24±1.23℃, a DO concentration decrease of 10.90±3.92 μmol/L (decrease of 6.3%), a pH decline of 0.36±0.02, and a NPP reduction of -17.7±6.2 mg/(m2·d) (decrease of 12.9%) relative to the current levels (1980-2005) by the end of this century. The co-occurrence of these changes and their cascade effects are expected to induce considerable biological and ecological responses, thereby making the ECS among the most vulnerable ocean areas to future climate change. Despite high uncertainties, our results have important implications for regional marine assessments.Keywords：Coupled Model Intercomparison Project (CMIP5);sea surface temperature (SST);dissolved oxygen (DO);seawater pH;net primary productivity4|3|4Updated：2023-04-27
- Abstract：To investigate the relationship between surface currents and wave distributions in typhoons, we took the Typhoon Talim in 2017 as a case, and found that the track of the typhoon winds up to 50 m/s was almost consistent with the Kuroshio track, particularly from September 13 to 16, 2017. The surface current data, derived from the NCEP Climate Forecast System Version 2 (CFSv2) from the National Center of Atmospheric Research (NCAR), revealed that the speed of the wind-induced current exceeded that of the Kuroshio in the region with the maximum wind speed. In this study, was utilized a third-generation numeric wave model, WAVEWATCH-Ⅲ (the latest version 5.16), developed by the National Oceanic and Atmospheric Administration (NOAA), to simulate the wave fields of Typhoon Talim using the European Centre for Medium-Range Weather Forecasts (ECMWF) reanalysis wind data in 0.125°×0.125° grid as the forcing field. We found that the root-mean-square error (RMSE) of the significant wave height (SWH) was 0.34 m when validated against measurements from altimeter Jason-2. In addition, we discovered that the SWH had a similar tendency to the change in the surface current speed that was approximately 0.5 m/s at the beginning of Typhoon Talim. However, the relationship became weak as the surface current speed was below 0.2 m/s. Our findings show that the distribution of typhoon waves is resulted from the interaction of surface current and the wind-sea portion of the wave system, since the distribution pattern of wind-sea is consistent with the surface current, and there is a weak relationship between surface current and swell.Keywords：current;typhoon wave;WAVEWATCH-Ⅲ model4|0|5Updated：2023-04-27
- Abstract：Mesoscale eddies are common oceanic phenomena. Although many related studies have been conducted, the ability for mesoscale eddies to carry real particles remains poorly addressed. We considered the drifters as real particles to characterize the capability of mesoscale eddies to carry particles. Firstly, mesoscale eddies in the northwest Pacific (99°E-180°E, 0°-66°N) were identified using sea level anomaly (SLA) data from 1993 to 2015. Secondly, three important parameters (the carrying days, the number of circles the drifter revolving around the eddy center, and the carrying distances) were calculated by colocalizing eddy data with drifters. Finally, statistical analysis and composite analysis were conducted, reflecting the capability of mesoscale eddies to carry particles. The mechanisms on the carrying capability of eddies were also discussed. Results show that (1) the motion of carried drifters reflects the upper limit of rotational speed of eddies that the drifters revolve around the eddy center by ≤ 90° for one day in most cases; (2) the drifters tend to be carried for a longer time when their minimal distances to the eddy center measured with normalized distance are small; (3) there are two types of eddies (cyclonic and anticyclonic eddies) in different subregions of northwest Pacific, and each has a different carrying capability (on average, similar in the tropical ocean and Subtropical Countercurrent, cyclonic eddies tend to have stronger carrying capability in Southern Kuroshio Extension, and anticyclonic eddies tend to have stronger carrying capability in Northern Kuroshio Extension and Subarctic Gyre); (4) on average, the carried drifters tend to travel for a longer time around the normalized eddy radii ranging from 0.41 to 0.76; (5) the carrying days are related to the Rossby number of the eddy (in general when the Rossby number is smaller, the carrying days are longer).Keywords：mesoscale eddy;drifter;Rossby number;composite analysis;carrying capability4|0|5Updated：2023-04-27
Special Section on Indo-Pac Project
- Abstract：An ensemble-based method for the observation system simulation experiment (OSSE) is employed to design optimal observation stations and assess the present observation stations in the northeastern South China Sea (SCS). We employed the 20-year (1992-2012) sea surface height (SSH) data to design an array to monitor the intraseasonal to interannual variability. The results show that the most key region was found located at the northwest of Luzon Island (LI) where the energetic Luzon cyclonic gyre (LCG) occurs; other key regions include the edge of the LCG, the northwest of the Luzon Strait (LS), and the southwest of Taiwan, China. By contrast, we found that the present observation stations might oversample at the northwest of the LS and undersample at the northwest of LI. In addition, the optimal stations perform better in a larger area than the present stations. In vertical direction, the key layer is located within the upper 200-m depth, of which the surface and subsurface layers are most valuable to the observing system.Keywords：assimilation;observation system simulation experiment (OSSE);ensemble;South China Sea (SCS);Kalman filter4|0|1Updated：2023-04-27
Physics
- Abstract：Changes in the marine productivity and sedimentary environment since the last deglaciation in the Ross Sea are presented in this paper. Opal has replaced calcium carbonate as the major biogenic component and has a significantly positive correlation with total organic carbon (TOC), which indicates that siliceous phytoplankton controlled the absorption and release of carbon by the biological pump and was the main producer of marine organic matter. Using the AMS 14C age framework, foraminiferal fossils and redox sensitive elements (RSEs), we found that both the sedimentary environment and marine productivity changed clearly in ~11 cal ka BP, which is more likely related with the melting and retreat of the Ross Ice Shelf. In addition, the increase of marine productivity promoted the sinking of more organic-matter to the seabed. A large proportion of oxygen in the bottom water body was consumed and more carbon dioxide was produced during the decomposition of organic matter, making the bottom water body more soluble to calcium carbonate.Keywords：biogenic components;marine productivity;redox environment;ice shelf retreat;the Ross Sea4|2|1Updated：2023-04-27
Geology
- Abstract：Jellyfish blooms occur worldwide and have resulted in serious problems in tourism, fisheries, coastal industries, and the marine ecosystem. The life cycle of scyphozoan jellyfish consists of a pelagic medusa stage and a benthic polyp stage. Success of asexual reproduction of the polyps determines directly the number of medusae; thus, the polyp stage is the key to understanding the population dynamics of medusae. Nemopilema nomurai, Aurelia coerulea, and Rhopilema esculentum are three scyphozoan jellyfish commonly inhabit in Chinese coastal waters. Polyps of A. coerulea are easily visible, while those of N. nomurai and R. esculentum remain yet to be found in the wild. However, distribution of the medusa indicates that the polyps of all three species may occur together. To evaluate the distribution pattern of polyps of the three species and explore intraguild predation by the polyps, we conducted a laboratory experiment that considered the attachment sequence and size relationship of calyx diameter of the polyps. We found that the polyps of A. coerulea preyed on polyps of the other two species in all treatments, except when polyps of R. esculentum were bigger than those of A. coerulea. The polyps of R. esculentum preyed on the polyps of N. nomurai only when polyps of R. esculentum attached first and were bigger than those of N. nomurai. Colonies of N. nomurai polyps were rarely found in the places inhabited by A. coerulea polyps. In addition, A. coerulea polyps are known to inhabit at depths of less than 20 m in coastal sea, thus, we speculate that N. nomurai polyp colonies might occur at depths of more than 20 m. Therefore, our finding that polyps of A. coerulea aggressively preyed on polyps of other species may help understand other such systems of jellyfish bloom in the world.Keywords：jellyfish bloom;polyps;intraguild predation;nature habitats4|3|2Updated：2023-04-27
- Abstract：Zooplankton distributions are largely influenced by both biotic and abiotic factors in the surrounding environment. Some zooplankton species can be used as bio-indicators for particular currents and water masses to help discover the dynamics of water current in the ocean. In this study, we investigated the distribution of zooplankton in North Yellow Sea (NYS) during winter when the Yellow Sea Warm Current (YSWC) influenced that area. Zooplankton communities in the NYS were dominated by temperate and warm-temperate species, such as Calanus sinicus, Paracalanus parvus, Acartia bifilosa, and Sagitta crassa. Two warm-water species, Eucheata plana and Sagitta enflata were also present. Cluster analysis grouped NYS zooplankton into three communities, the Shandong Coastal Community (SCC) in the Shandong neritic area, the Yellow Sea Central Community (YSCC) in the central waters of the NYS, and the Liaoning Coastal Community (LCC) in the Liaoning neritic area. Abundances varied significantly among these communities, with an average of 102.2 ind./m3 in SCC, 179.8 ind./m3 in YSCC, and 1 244.2 ind./m3 in LCC. Depth and the bottom (3 m from the sea floor) temperature were likely the primary abiotic factors influencing zooplankton distributions. The appearance of E. plana, an indicator species for the YSWC path, indicated a significant northwestward trend for the YSWC in 2007.Keywords：North Yellow Sea;Yellow Sea Warm Current;zooplankton;bio-indicator;community structure4|2|0Updated：2023-04-27
- Abstract：To understand the relationship between planktonic diatoms and environmental variables in the lakes on the Songnen Plain, northeast (NE) China, we investigated water quality and planktonic diatoms from 71 sampling points in 27 lakes, based on which Canonical Correspondence Analysis (CCA) was conducted. The result show that planktonic diatoms displayed certain responses to environment gradients, and the total phosphorus (TP) explained the maximum variation of planktonic diatom species among the 15 environmental variables, suggesting that TP was the most important and significant environmental parameter affecting the distribution of diatom species. In addition, we established a diatom-total phosphorus transfer (DTPT) function, of which component 5 of the weighted averaging partial least squares regression (WAPLS) was chosen to and compared with a series of weighted average regression (WA) models and WA-PLS models. According to the jackknifing statistical test, the component 5 of WA-PLS models provided a lower root-mean-square error prediction (RMSEP=0.202) and a higher correlation coefficient between observation and prediction (R2_Jack=0.759). After deletion of three outliers, the root-mean-square error prediction of the DTPT function was reduced (RMSEP=0.169) while the correlation coefficient between observation and prediction was increased (R2_Jack=0.823). Therefore, this DTPT function performed better than other regional TP models in the world. However, it remains demanding for expanding the background dataset to improve the prediction ability of the model.Keywords：Songnen Plain;diatom;total phosphorus;transfer function6|2|3Updated：2023-04-27
- Abstract：Artificial Neural Network (ANN) models have been extensively applied in the prediction of water resource variables,and Geographical Information System (GIS) includes powerful functions to visualize spatial data. In order to provide an efficient tool for environmental assessment and management that combines the advantages of these two modules,a GIS-based ANN water quality prediction system was developed in the present study. The ANN module and ArcGIS Engine module,along with a dynamic database,were imbedded in the system,which integrates water quality prediction via the ANN model and spatial presentation of the model results. The structure of the ANN model could be modified through the graphical user interface to optimize the model performance. The developed system was applied to a real case study for the prediction of the total phosphorus concentration in the Lake Champlain area. The prediction results were verified with the monitoring data,and the performance of the developed model was further evaluated through graphical techniques and quantitative statistical methods. Overall,the developed system provided satisfactory prediction results,and spatial distribution maps of the predicted results were obtained,which coincided with the monitored values. The developed GIS-based ANN water quality prediction system could serve as an efficient tool for engineers and decision makers.Keywords：water quality prediction;Geographical Information System (GIS);artificial neural network;integration;system development6|4|0Updated：2023-04-27
- Abstract：The China National Blue Bay Remediation Action Plan (NBBRAP) is a crucial step towards achieving the overall goal of building a maritime power and a beautiful ocean. This paper presents the resource-environment-economy (REE) composite system from the three-dimensional perspective of REE. Especially,through the coordination degree model of the composite system based on the order degree of subsystems,empirical analysis of the coordination degree of the REE composite system in a typical coastal city Qingdao from 2005 to 2016 was carried out. Results indicate that the degree of coordination and interactive coordination of the REE composite system in Qingdao were in a low-quality state. Qingdao's economy development depended largely on the expense of over-exploitation of resources and environmental degradation in 2013-2015. Government policy implementation was less persistent in 2009-2010 and 2011-2013. The immediate stimulating effect was significant,making the coordination degree of the REE composite system fluctuate in a volatile manner. Analysis of the coordination degree of the REE composite system has practical guiding significance for the successful implementation attainment of the NBBRAP target in Qingdao and is conducive to deepening the learning and promotion of this plan in other coastal cities.Keywords：China National Blue Bay Remediation Action Plan;resource-environment-economy;coordination4|2|0Updated：2023-04-27
Ecology
- Abstract：Lake eutrophication is recognised as a serious global challenge, and many regional legislative programmes are being made to attempt to relieve nutrient pollution and restore deteriorated lake ecological state. However, it is of primary importance to understand the degradation processes and reference conditions. The palaeolimnological approach allows us to use ecological evidences preserved in lake sediments to track the changes of lake trophic status under human impact. Diatoms, a proxy for ecological and limnological change, and pigments, a proxy for algal production and composition, were analysed on a short sediment sequence from Lake Dojran (Republic of North Macedonia and Greece), and their preservation qualities were evaluated before environmental interpretation. Good diatom preservation is inferred mainly from the consistent co-occurrence of robust, highly-silicified taxa and small taxa throughout the sequence. Pigment evaluation of the comparison between wet sediment samples in dark and cold storage and their corresponding dry sediment samples lyophilized immediately after the recovery reveals that sediment restoration conditions are critical for the accuracy of analysis. We show that the increased chlorophyll and xanthophyll pigment concentrations, particularly the siliceous-algae pigment fucoxanthin and diatoxanthin, together with the distinct increase in diatom concentration, indicate accelerated lake eutrophication and a major ecological shift linked to intensified water abstraction practice and agricultural expansion in the late 18th to early 19th century. Evidence of diatom assemblage composition is muted probably by the dominance of widely-tolerant small fragilaroid species in diatom composition and the better competitive ability of cyanobacteria and chlorophytes than diatoms for low light under eutrophic and turbid conditions. This study improves our understanding of recent human-induced environmental change and current ecological restoration target in this lake.Keywords：diatom, pigment;Lake Dojran;Mediterranean;lake eutrophication;palaeolimnology4|2|0Updated：2023-04-27
- Abstract：Seabed photographing has been applied with various underwater camera apparatuses (UCAs) for observations of megabenthic epifauna, which reveals more details than traditional sampling tools do. In this study, we improved a UCA named a towed underwater video-camera system (TUV system) with image processing software for seabed photographing in coastal areas up to 100 m. In May 2017, the TUV system was tested at 4 stations in the Zhangzi Island marine area in the northern Yellow Sea to investigate local megabenthic epifauna, especially brittle stars. At each station, more than 500 good seabed photographs each in area of 0.155 0 m2 were obtained in just 10 min. Almost all of the epifauna larger than 1 mm could be identified from the photographs, including echinoderms, bivalves, cnidarians, and crustaceans. Three dominant brittle stars (Ophiopholis mirabilis, Ophiura sarsii vadicola, and Stegophiura sladeni) were spotted, and their abundance, disc diameter, cluster size, and coverage area were calculated and analyzed from the seabed photographs. The results show that the TUV system could be applied in coastal waters of hard sandy bottoms and could be used for quantitative investigations of megabenthic epifauna.Keywords：seabed photography;brittle stars;underwater camera apparatuses (UCAs);coastal waters4|3|1Updated：2023-04-27
- Abstract：To evaluate the status and changes of macrobenthic communities related to the construction of the Longkou Artificial Island (LAI) in the Bohai Sea, China, four annual surveys were conducted from 2010 to 2013. Significant changes on environmental variations and macrobenthic communities were observed in 2013 after the LAI construction a couple of years later. The changing environment was primarily presented by lower values of pH, dissolved oxygen (DO), organic material (OM) percentage, and higher salinity, suspended particulate matter (SPM) concentration and oil concentration. The main dominant species shifted from Polychaeta taxa in 2010 to Mollusca taxa in 2013 due to the changes of environmental variables. An apparent miniaturization tendency in body size of macrobenthic species was presented from 2010 to 2013. The biodiversity indices increased yearly from 2010 to 2013. However, inter-site homogenization was observed in both the community structure and health status. Multivariate AZTI Marine Biotic Index (M-AMBI) analysis showed that the health status of stations changed depending on its original status and distance to the LAI. However, no significant differences were found in the spatial distribution of either environmental variables or abundance, biomass and biodiversity of macrobenthic communities. All the results will provide a basis for the long-term ecological assessment of reclamation.Keywords：macrobenthic assemblages;benthic health assessment;M-AMBI index;Longkou Artificial Island;Bohai Sea4|2|0Updated：2023-04-27
- Abstract：Coexisting floating-leaved and submerged plants experience similar environmental changes but may evolve different patterns of genetic variation. To compare local-scale genetic variation, we collected samples of floating-leaved Nymphoides peltata and submerged Myriophyllum spicatum coexisting in a disturbed urban lake in China. At the subpopulation level, using microsatellites, M. spicatum had higher clonal diversity than N. peltata. M. spicatum had 28.4% multilocus genotypes (MLGs) shared between subpopulations, but N. peltata had only one MLG shared between two adjacent subpopulations. N. peltata displayed more genetic variation between subpopulations than within subpopulations, but the reverse was true for M. spicatum. Principal components and Bayesian cluster analyses showed that individuals from each subpopulation of N. peltata tended to have relatively close genetic relationships. For M. spicatum, individuals from each subpopulation were genetically scattered with those from other subpopulations. Our results imply that in unpredictable adverse environments M. spicatum may be less subjected to local-deme extinction than N. peltata because of genetically diverse clones at the subpopulation level. This characteristic means that following adverse events, M. spicatum may rapidly restore subpopulation distributions via recolonization and intense gene flow among subpopulations.Keywords：aquatic plants;life forms;microsatellites;clonal diversity;eutrophic lake4|3|1Updated：2023-04-27
- Abstract：Euglena gracilis is a unicellular green eukaryotic microalga that features characteristics of both plants and animals. The photosynthetic function of its chloroplast is easily lost under stress resulting in bleached mutants,while the physiological role of their residual plastid DNAs remains unclear. In this study,we obtained five bleached mutants by ofloxacin (Ofl) treatment,identified 12 residual plastid genes in five bleached mutants,and determined the mRNA levels in the wild type E. gracilis (WT) and one bleached mutant (OflB2) under dark and light stimulation conditions by quantitative reverse transcribed PCR (qRTPCR). Results show that the expression of all selected plastid genes in both WT and OflB2 mutant did not change significantly in darkness,while their responses to light stimulation were different. Under the light stimulation conditions,half of the genes did not change significantly,while most of the other genes were down-regulated in OflB2 mutant and up-regulated in WT. Therefore,the bleached mutant retains part of the plastid genome and the plastid relic is responsive to light. Our research will help to understand the functions of residual plastid DNA and evolution of chloroplasts.Keywords：Euglena gracilis;bleached mutant;residual plastid genes;light response4|0|0Updated：2023-04-27
- Abstract：Nannochloropsis oceanica is a marine microalgal species with both economic value and biological importance. It grows fast,contains rich oils,reproduces asexually,holds a small and haploidy genome,and is easy to be modified genetically. However,the genetic study of N. oceanica is scarce. Very less genetic bases of its traits have been deciphered,and no gene has been isolated from it with the function verified simultaneously via either genetic or reverse genetic approaches or both (de novo cloned). Changing medium salinity may aid to control harmful organisms met during large scale cultivation. As a stress,it may also facilitate the accumulation of desirable chemicals including fatty acids. In order to decipher the genetic basis of the low salinity tolerance of N. oceanica,we mutated N. oceanica with Zeocin. In total,five mutant bulks were constructed at equal number of cells,100 mutants each,which were tolerant to a discontinuous serial of salinities from that of 100% of f/2 to that of a mixture of 4% of f/2 and 94% of BG11. The bulks were genotyped through whole genome re-sequencing and analyzed with bulked mutant analysis (BMA) newly modified from bulked segregant analysis (BSA). In total,47 SNPs and 112 InDels were found to associate with the low salinity tolerance,and around them a set of low salinity tolerance associating genes were identified. A set of annotatable genes commonly found between control and different salinities indicated that the genes functioning in gene expression,energy metabolism and cellular structure may be involved in the low salinity tolerance. These associating molecular markers and genes around them were not enough for outlining the physiological mechanism underlining the tolerance; however they should aid to improve N. oceanica genetically.Keywords：Nannochloropsis oceanica;bulked mutant analysis (BMA);low salinity tolerance4|0|0Updated：2023-04-27
- Abstract：Acanthogobius ommaturus,a fish species of the Family Gobiidae,is a marine commercial fish perched on the bottom of seawater. In this study,Illumina high-throughput sequencing technology was applied to obtain the candidate microsatellite markers of A. ommaturus. A total of 4 746 microsatellite-rich fragments were found,of which 4 542 microsatellites are with primer fragments,containing 971 dinucleotide sequences,2 643 trinucleotide sequences,569 tetranucleotide sequences,406 pentanucleotide sequences,and 212 hexanucleotide sequences. Based on the results of high-throughput sequencing,a total of 141 pairs of the microsatellite primers were designed and screened. And then 24 polymorphic primers were finally obtained by polyacrylamide gel electrophoresis. In total,271 alleles were detected in the 24 pairs of primers. The number of alleles for different primers ranged from 5 to 19. The average number of effective alleles (Na) was 11.292; the average observed heterozygosity (Ho) of the 24 pairs of primers was 0.665,the average expected heterozygosity (He) was 0.880,and the average polymorphic information content was 0.846. All sites were highly polymorphic (PIC>0.50).Keywords：microsatellite;Acanthogobius ommaturus;high-throughput sequencing;polymorphic sites4|0|2Updated：2023-04-27
- Abstract：Thymidylate synthase (TS) is a key enzyme in the de novo biosynthesis of thymidine monophosphate, serving as a well-known drug target in chemotherapy against cancers and infectious diseases. Additional to its clinical value, TS is supposed to be a promising drug target in aquatic-disease control. To facilitate designing pathogen-specific TS inhibitors for shrimp-disease control, we report the crystal structures of TS from Litopenaeus vannamei (LvTS) in the apo form, LvTS-dUMP complex and LvTS-dUMP-raltitrexed complex at 2.27 Å, 1.54 Å, and 1.56 Å resolution, respectively. LvTS shares a similar fold with known TSs, existing as a dimer in the crystal. The apo LvTS and LvTS-dUMP take an open conformation, and raltitrexed binding induces structural changes into a closed conformation in LvTS-dUMP-raltitrexed. Compared to those in other known TS-dUMP-raltitrexed complexes with the closed conformation, the C-terminal loop in LvTS-dUMP-raltitrexed shifts its position away from the bound raltitrexed; the distance between C6 of dUMP and Sγ of the catalytic cysteine is obviously longer than that in the known TS structures with closed conformations, resembling that in the TS structures with open conformations. Other species-specific interactions with dUMP and raltitrexed are also observed. Therefore, LvTS-dUMP-raltitrexed adopts a loosely closed conformation with structural features intermediate between the closed and the open conformations that were reported in other TSs. Our study provides the first crustcean TS structure, and reveals species-specific interactions between TSs and the ligands, which would facilitate designing pathogen-specific TS inhibitors for shrimp-disease control.Keywords：thymidylate synthase (TS);closed conformation;deoxyuridine monophosphate (dUMP);thymidine monophosphate (TMP);raltitrexed;Litopenaeus vannamei4|0|0Updated：2023-04-27
-
Description of
Cephalodella changdensis sp. nov. (Rotifera: Notommatidae) from Hunan Province, ChinaAbstract：A new freshwater rotifer Cephalodella changdensis sp. nov. discovered in two locations in Changde, Hunan, China, is described morphologically. The new species is characterized by body shape moderately elongate, double eyespots frontally, toes conical and almost straight, about one fourth of total length, trophi type B (classification after Wulfert, 1937), rami asymmetrical with a pair of long alulae, fulcrum inverted T-shaped (ventral/dorsal view) with dorsally directed distal projection (lateral view), and manubria asymmetrical, left one slightly longer and stronger, with J-shaped or crutch-shaped posterior ends.Keywords：rotifer;new species;Cephalodella changdensis sp. nov.;taxonomy;trophi asymmetrical4|0|0Updated：2023-04-27 - Abstract：A new free-living marine nematode species of the genus Leptolaimus belonging to the family Leptolaimidae was collected from intertidal sediments of the Shenzhen Mangrove Nature Reserve, Shenzhen, South China, and it is described here as Leptolaimus holovachovi sp. nov. The new species is characterized by body length 734-896 μm in males and 822-941 μm in females; papilliform cephalic sensilla; circular amphideal fovea; males with 7-14 anterior midventral alveoli in the pharyngeal region, 4-5 midventral tubular precloacal supplements and 4-6 alveolar precloacal supplements; spicules slender, slightly arcuate, proximally cephalated and distally pointed. Plate-like gubernaculum without apophyses. The new species differs from other congener species of the genus by the unique feature of having anterior midventral alveoli in the pharyngeal region.Keywords：new species;free-living marine nematode;taxonomy;South China Sea4|0|0Updated：2023-04-27
- Abstract：Integrated Multi-Trophic Aquaculture (IMTA) is an effective method for sustainable aquaculture as species from different trophic levels could reduce negative effects from fed species in the environment. A proper proportion of different trophic species in an IMTA system could improve the aquaculture production and environmental sustainability. At present, research on the proper proportions for farming species is scarce. We investigated the effects of IMTA modes of oyster (Crassostrea gigas) and kelp (Saccharina japonica) in different weight ratios on water quality and carbonate system in a closed enclosure experiment for three days in the Sanggou Bay in Shandong Province, China, in December 2017. Nine collocation modes in oyster:kelp weight ratio were tested showing as 24:3, 24:2, 24:1, 16:3, 16:2, 16:1, 8:3, 8:2, and 8:1. The water parameters were determined at 17:00 on Day 1 (D1), and 6:00 and 17:00 on Days 2 (D2) and 3 (D3). As two-way ANOVA showed, all increased parameters (dissolved oxygen (DO), pH, chl a, the carbonate system and pCO2) were significantly related to oyster-kelp modes, and interaction between modes and time were also significant (P < 0.05). On the 3th day, the 8:3 mode was the highest in DO, pH, chl a, CO32- (P < 0.05), and dissolved inorganic carbon (DIC), HCO3-, CO2, and pCO2 were the lowest (P < 0.05). According to previous references and the results of this study, the appropriate oyster:kelp proportion at the beginning of winter is from 8:2 to 8:3. The results of this study may help government to optimize the aquaculture structure of Sanggou Bay.Keywords：Integrated Multi-Trophic Aquaculture (IMTA);Pacific oyster;Crassostrea gigas;kelp;Saccharina japonica4|0|2Updated：2023-04-27
- Abstract：The effects of three environmental factors,salinity,carbonate alkalinity,and pH,on the survival,feeding,and respiratory metabolism of Eogammarus possjeticus (Amphipoda:Gammaridae) were investigated experimentally. The results show that E. possjeticus could tolerate a broad salinity range. The 24-h lowest median lethal salinity was 2.70,and the highest was 47.33. The 24-h median lethal alkalinity and pH were 23.05 mmol/L and 9.91,respectively; both values decreased gradually with time. Different values of salinity,carbonate alkalinity,and pH resulted in significant differences in the cumulative mortality (P < 0.05). The ingestion rate and feed absorption efficiency were significantly affected by the coupling of the three environmental factors (P < 0.05). With increases in carbonate alkalinity,salinity,and pH,both ingestion rate and feed absorption efficiency exhibited a downward trend,indicating a decline in feeding ability under high salinity and more alkaline water conditions. The coupling of salinity,carbonate alkalinity,and pH also had a significant effect on respiration and excretion (P < 0.05). The oxygen consumption rate increased first and then decreased with increasing carbonate alkalinity. Under the same carbonate alkalinity values,the oxygen consumption rate increased with increasing salinity. Under the same carbonate alkalinity and salinity,the oxygen consumption rate initially increased and then decreased with increasing pH. The O:N ratio first increased and then decreased with increasing carbonate alkalinity. When carbonate alkalinity was less than 6 mmol/L,the O:N ratio increased with increasing salinity and decreased with increasing pH. The results demonstrate that changes in salinity,carbonate alkalinity,and pH had a measurable impact on the osmotic pressure equilibrium in E. possjeticus and affected the energy supply mode (i.e. ratio of metabolic substrate).Keywords：Eogammarus possjeticus;saline and alkaline water;feeding;respiratory metabolism4|0|0Updated：2023-04-27
- Abstract：A 240-day feeding trial was conducted to investigate the effects of dietary vitamin C on growth performance,anti-oxidative response,and fatty acid composition of juvenile abalone Haliotis discus hannai Ino (initial body weight:0.93±0.00 g). Three semi-purified experimental diets were formulated containing 0.00,94.52,and 9 649.58 mg/kg of vitamin C supplied as L-ascorbyl-2-monophosphate. The results show that there was no significant difference in weight gain ratio,daily increment in shell length,and survival rate among the three treatments. Adding dietary vitamin C (9 649.58 mg/kg) significantly increased the activities of superoxide dismutase (SOD),glutathine peroxidase (GPX),glitathione-S-transferase (GST),glutathione reductase (GR),alkaline phosphatase (AKP),and lysozyme in viscera (P < 0.05). In muscle,activities of phenoloxidase,catalase,SOD,GST,GR,and AKP were increased in the treatment with 9 649.58 mg/kg of dietary vitamin C (P < 0.05). The highest concentrations of ascorbic acid in viscera and muscle were found in the group with 9 649.58 mg/kg of dietary vitamin C (P < 0.05). The contents of crude protein and crude lipid in the soft body were significantly increased in the 9 649.58 mg/kg group (P < 0.05). Dietary vitamin C supplementation significantly decreased the contents of saturated fatty acids (14:0,16:0,and 18:0),and increased the composition of 18:2n-6 and 22:6n-3 in the soft body of abalone (P < 0.05). Therefore,although there were no significant effects on the growth performance,dietary vitamin C supplementation improved the anti-oxidation and immune responses,increased specific unsaturated fatty acid (i.e.,16:1,18:1n-7,18:1n-9,18:2n-6 and 22:6n-3),and decreased specific saturated fatty acid (i.e.,14:0,16:0 and 18:0) contents in the soft body of abalone.Keywords：abalone;ascorbic acid;anti-oxidative capability;fatty acid6|2|0Updated：2023-04-27
- Abstract：The Pacific saury (Cololabis saira) is one of the major harvested species in the temperate waters of the northwestern Pacific Ocean (NPO). The Catch-MSY model uses catch data and basic life history information to estimate the Maximum Sustainable Yield (MSY) for data-limited fisheries. Since there is considerable uncertainty in the current status of the Pacific saury stock in the NPO,the Catch-MSY model was used in this study to estimate MSY on the basis of catch data and life history information from the North Pacific Fisheries Commission (NPFC). During the process,17 scenarios,according to different prior distributions of the intrinsic rate of increase (r) and carrying capacity (K),were set for sensitivity analysis. Moreover,the influence of different catch time series and different process errors were taken into account. The results show the following:(1) there was a strong negative correlation relationship between ln(r) and ln(K); the MSY increases with an increase in the lower limit of r; (2) The time series of catch data had a limited impact on the assessment results,whereas the results of the model were sensitive to the annual catch in the first and last years; (3) The estimated MSYs of the Pacific saury were 47.37×104 t (41.57×104 t to 53.17×104 t) in scenario S1A and 47.53×104 t (41.79×104 t to 53.27×104 t) in scenario S1B. Given the uncertainty of the Catch-MSY model,maintaining a management target between 50×104 t and 70×104 t was a better management regulation. This study shows that the Catch-MSY model is a useful choice for estimating the MSY of data-limited species such as the Pacific saury.Keywords：Cololabis saira;Catch-MSY model;intrinsic rate of increase;maximum sustainable yield;northwest Pacific Ocean4|0|0Updated：2023-04-27
Biology
- Address：Editorial Office of JOL, 88 Haijun Rd. Qingdao, 266000, China
- Tel：+86-532-82898754 Email：jol@qdio.ac.cn
- Technical support is provided by Beijing Founder electronics co., LTD 京ICP备09064830号-19
京公网安备11010802024621 - It is recommended to read the content of this site in Chrome&IE9+. Please switch to extreme mode in browser 360.
- Cookies We use cookies to help provide and enhance our service and tailor content. By continuing, you agree to the use of cookies.
0