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Volume 38 ， Issue 1 ， 2020
- Abstract：Vigorous mesoscale eddies and significant sea surface temperature (SST) variations are found in the northern edge of the Pacific warm pool that features large SST gradient. However, the relations between SST gradient, eddies, and SST variations in this region remain unexplored. In this study, by combining multi-altimeter sea surface height (SSH), satellite microwave SST observations and a mesoscale eddy dataset, we investigated the two-dimensional structures of SSTa (SST anomalies) in two subareas, which have different eddy characteristics and can be discriminated in the intensity of background SST gradient. The eddy characteristics of this region, focusing on their concentration to 21°N, are also described. We found that eddies can result in two distinct patterns of eddy-induced SST anomalies, with two different horizontal processes respectively. One is a monopole pattern that is caused by elevation/depression of the isopycnals, and another is a dipole pattern caused by eddy's rotation and stirring of the background SST field. In addition, contributions of both parts to the total SSTa and the SSTa variations were evaluated. The intensity of surrounding SST gradient plays an important role in shaping the SSTa structure:when SST gradient is larger, the eddy-associated SSTa pattern organizes more dipole. The distinct annual cycle in two components of SSTa is associated with the seasonal modulation of the warm pool's horizontal structure.Keywords：mesoscale eddy;sea surface temperature (SST) anomaly;trap effect;stirring effect;heat transport4|2|3Updated：2023-04-27
- Abstract：Subtropical sea surface salinity (SSS) maximum is formed in the subtropical South Indian Ocean (SIO) by excessive evaporation over precipitation and serves as the primary salt source of the SIO. Spaceborne SSS measurements by Aquarius satellite during September 2011-May 2015 detect three disconnected SSS maximum regions (>35.6) in the eastern (105°E-115°E, 38°S-28°S), central (60°E-100°E, 35°S-25°S), and western (25°E-40°E, 38°S-20°S) parts of the subtropical SIO, respectively. Such structure is however not seen in gridded Argo data. Analysis of Argo profile data confirms the existence of the eastern maximum patch and also reveals SSS overestimations of Aquarius near the western and eastern boundaries. Although subjected to large uncertainties, a mixed-layer budget analysis is employed to explain the seasonal cycle of SSS. The eastern and central regions reach the highest salinity in February-March and lowest salinity in August-September, which can be well explained by surface freshwater forcing (SFF) term. SFF is however not controlled by evaporation (E) or precipitation (P). Instead, the large seasonal undulations of mixed layer depth (MLD) is the key factor. The shallow (deep) MLD in austral summer (winter) amplifies (attenuates) the forcing effect of local positive E-P and causes SSS rising (decreasing). Ocean dynamics also play a role. Particularly, activity of mesoscale eddies is a critical factor regulating SSS variability in the eastern and western regions.Keywords：sea surface salinity (SSS);subtropical salinity maximum;Aquarius;Argo float;freshwater flux4|2|0Updated：2023-04-27
- Abstract：Based on the data from a special project titled China's Offshore Marine Integrated Investigation and Evaluation as well as Regional Ocean Modeling Systems (ROMS) diagnostic numerical model, we studied the influence of high wind processes on the circulation and water exchange between the Bohai and Yellow Seas (BYS) in winter. The results show that the vertical structure of the Yellow Sea Warm Current (YSWC) is relatively uniform under condition of high winds, showing obvious barotropic features. However, this flow is not a stable mean flow, showing strong paroxysmal and reciprocating characteristics. A comparison of the changes in sea level suggests that the intensity of the northwards upwind flow is consistent with the abnormal fluctuations in the sea level. It indicates that the upwind flow is closely related to the water exchange between the BYS. The impact of high wind processes on the water exchange between the BYS is enormous. It can make the flux through the Bohai Strait, as well as that through the mouth of each constituent bay (i.e., Liaodong Bay, Bohai Bay, and Laizhou Bay) far greater than usual, resulting in a significant increase in the water exchange rate. The exchange capacity, which is about 8% of the total volume of the Bohai Sea, can be completed in a few days. Therefore, the water exchange of the Bohai Sea may be completed by only a few occasional high wind processes in winter.Keywords：high wind;Yellow Sea Warm Current (YSWC);sea level rise or drop;water exchange4|2|1Updated：2023-04-27
- Abstract：The emulsification of crude oil is caused by the oil flowing into the water, resulting in the increase of oil film tension, viscosity, water content, and volume, which brings great harm to the marine ecological environment and difficulties for the cleanup of marine emergency equipment. The realization observation of emulsification crude oil will increase the response speed of marine emergency response. Therefore, we set up crude oil emulsification samples to study the physical property in laboratory and conducted radar measurements at different incidence angles in outdoor. The radar is C band in resolution of 0.7 m by 0.7 m. A fully polarimetric scatterometer (HH, VV, and VH/HV) is mounted at 1.66 m (minimum altitude) height at an incidence angle between 35° and 60°. An asphalt content of less than 3% crude oil and the filtered seawater were used to the outdoor emulsification scattering experiment. The measurement results are as follows. The water content can be used to describe the process of emulsification and it is easy to measure. Wind speed, asphalt content, seawater temperature, and photo-oxidation affect the emulsifying process of crude oil, and affects the normalized radar cross section (NRCS) of oil film but wind is not the dominant factor. It is the first time to find that the emulsification of crude oil results in an increase of NRCS.Keywords：emulsification of crude oil;normalized radar cross section (NRCS);water content;wind speed;temperature4|3|3Updated：2023-04-27
- Abstract：Ocean internal waves appear as irregular bright and dark stripes on synthetic aperture radar (SAR) remote sensing images. Ocean internal waves detection in SAR images consequently constituted a difficult and popular research topic. In this paper, ocean internal waves are detected in SAR images by employing the faster regions with convolutional neural network features (Faster R-CNN) framework; for this purpose, 888 internal wave samples are utilized to train the convolutional network and identify internal waves. The experimental results demonstrate a 94.78% recognition rate for internal waves, and the average detection speed is 0.22 s/image. In addition, the detection results of internal wave samples under different conditions are analyzed. This paper lays a foundation for detecting ocean internal waves using convolutional neural networks.Keywords：ocean internal waves;faster regions with convolutional neural network features (Faster R-CNN);convolutional neural network;synthetic aperture radar (SAR) image;region proposal network (RPN)5|2|3Updated：2023-04-27
Physics
- Abstract：Plate subduction is the largest natural factory that processes elements,which controls recycling and mineralization of a variety of elements. There are three major ore deposit belts in the world:the circumPacific,the central Asian,and the Tethys belts. All the three belts are closely associated with plate subductions,the mechanism remains obscure. We approached this problem from systematic studies on the behaviours of elements during geologic processes. This contribution summaries the recent progress of our research group. Our results suggest that porphyry Cu deposits form through partial melting of subducted young oceanic crust under oxygen fugacities higher than ·FMQ~+1.5,which is promoted after the elevation of atmospheric oxygen at ca. 550 Ma. Tin deposits are associated with reducing magmatic rocks formed as a consequence of slab rollback. The Neo-Tethys tectonic regime hosts more than 60% of the world's total Sn reserves. This is due to the reducing environment formed during the subduction of organic rich sediments. For the same reason,porphyry Cu deposits formed in the late stages during the closure of the Neo-Tethys Ocean. Tungsten deposits are also controlled by slab rollback,but is not so sensitive to oxygen fugacity. Subduction related W/Sn deposits are mostly accompanied by abundant accessory fluorites due to the breakdown of phengite and apatite. Decomposition of phengite is also significant for hard rock lithium deposits,whereas orogenic belt resulted from plate subduction promote the formation of Li brine deposits. Cretaceous red bed basins near the Nanling region are favorable for Li brines. Both Mo and Re are enriched in the oxidationreduction cycle during surface processes,and may get further enriched once Mo-,Re-enriched sediments are subducted and involved in magmatism. During plate subduction,Mo and Re fractionate from each other. Molybdenum is mainly hosted in porphyry Mo deposits and to a less extent,porphyry Cu-Mo deposits,whereas Re is predominantly hosted in porphyry Cu-Mo deposits and sedimentary sulfide deposits.Keywords：plate subduction;oxygen fugacity;ore deposits;geochemical behaviors;subduction factory5|3|18Updated：2023-04-27
- Abstract：Fractional crystallization of basaltic magma at variable depths influences strongly the geochemical compositions of mid-ocean ridge basalts (MORBs),especially at slow-spreading mid-ocean ridges. The Carlsberg Ridge is a typical slow-spreading ridge located in the northwestern Indian Ocean. In this study,we conducted petrological,geochemical and modelling studies of MORBs collected along the Carlsberg Ridge from 57°-65°E to understand the fractional crystallization processes of magma and the controls on variations in MORB geochemistry. Our results show that the mantle sources beneath the Carlsberg Ridge are heterogeneous even on the local scale of a segment; such heterogeneity may be ubiquitous beneath the Carlsberg Ridge. Mantle heterogeneity may be caused by the enriched components resulting in the "DUPAL" anomaly,whereas the effect of pyroxenite on mantle heterogeneity is negligible. The parental melts experienced crystallization of olivine,plagioclase and clinopyroxene prior to eruption,which played a significant role in the major and trace element variations in MORBs from the Carlsberg Ridge. The liquid lines of descent (LLDs),deduced from the forward modelling of three parental magma compositions using the Petrolog3 program at pressures between 1 atm and 10 kbar,demonstrate that clinopyroxene joined the olivine and plagioclase cotectic. The over-enrichment in highly incompatible elements relative to LLDs may be caused by the processes of replenishment-tapping-crystallization in magma chambers. The calculated crystallization pressures suggest that parental magmas beneath the Carlsberg Ridge experienced moderateto high-pressure crystallization and that crystallization beneath the slow-spreading Carlsberg Ridge may start at upper mantle depths.Keywords：fractional crystallization;crystallization pressure;mantle heterogeneity;Carlsberg Ridge;midocean ridge basalt (MORB)4|2|2Updated：2023-04-27
Geology
- Abstract：Benthic algae communities dominate the primary production in littoral zone of shallow lake. To understand the long-term effect of alteration in the composition of benthic algae community assemblage in such as a lake in China,we analyzed the benthic algae developments and indicators in the Donghu Lake in Wuhan,central China in 2004 and 2014. We compared the benthic algae biomass,compositions,and species richness of aquatic macrophytes and the changes of primary physicochemical parameters. The results show that in the 10-year period,chl a and conductivity declined significantly but nutrient level of the whole lake remained largely stable. The benthic algae biomass doubled and the relative proportion of green algae increased,whereas the benthic diatom ratio decreased. The benthic diatom assemblages and taxa differed in a number of ways,showing more epiphytic diatom species,and the relative abundance and species richness changed markedly. The number of aquatic macrophyte species increased from 3 in 2004 to 15 in 2014, presenting a remarkable recovery from previous eutrophication conditions. The changes of water level,chl a,and conductivity played a crucial role in governing aquatic macrophytes re-colonization in the littoral zones in the period. The ecological characteristics of littoral benthic diatoms reflect habitat coupling as indicated by redundancy analysis. Therefore,the close link between benthic algae and macrophyte recovery demonstrates that the benthic algae metrics are much more useful than nutrient levels to quantify the process of restoration in the lake.Keywords：benthic algae;benthic diatom;lake restoration;aquatic macrophyte;water level4|2|1Updated：2023-04-27
- Abstract：Copper sulfate (CuSO4) is widely used in controlling the Microcystis aeruginosa blooms. Many studies reported the toxicity mechanisms of Cu2+ to M. aeruginosa at the physiological level,but little is known about a transcriptomic basis of these mechanisms. In the present study,M. aeruginosa was treated by 0.5 mg/L Cu2+ (half of the 96-h EC50) for 72 h. The results show that Cu2+ content in M. aeruginosa increased after 72 h Cu2+ exposure,whereas the Fv/Fm chlorophyll fluorescence value and chlorophyll a content in M. aeruginosa sharply decreased. Reactive oxygen species concentration and activity of antioxidant enzymes (superoxide dismutase,catalase and peroxidase) were all increased. These physiological data confirmed toxicity of Cu2+ to M. aeruginosa. The RNA-seq analysis showed that 6 646 725 and 7 880 291 clean reads were obtained for the Cu-treated and control libraries,respectively. The 595 genes (252 downward trend and 343 upward trend) with the Gene Ontology (GO) annotations were divided into three main functional categories:cellular component,molecular function,and biological process. In the Cluster of Orthologous Groups (COG) annotation,418 differentially expressed genes with 25 functional definitions were obtained. Among them,'replication,recombination and repair','energy production and conversion',and 'general function prediction only' were the largest three groups of transcripts. In the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis,genes involved in photosynthesis and oxidative phosphorylation were present at the highest percentages. In addition,the genes involved in photosynthesis and oxidative phosphorylation were identified,and then confirmed using real-time PCR. This study reported the first transcriptome of M. aeruginosa. Photosynthesis and oxidative phosphorylation were severely affected by Cu2+ toxicity,which may have contributed to cell death. These data provide the potential mechanism to explain the CuSO4 effect on the harmful M. aeruginosa.Keywords：transcriptome;physiology;Microcystis aeruginosa;copper sulfate4|0|1Updated：2023-04-27
- Abstract：Resting cysts play crucial roles in the ecology of dinoflagellates,especially in wintering or surviving unfavorable conditions,seeding harmful algal blooms (HABs),and facilitating the geographic expansion. Encystment of dinoflagellates is tightly coupled with sexual reproduction in most cases,which can occur either through homothallism (self-fertilization) or heterothallism (intercrossing of +/-strains). The types of sexual reproduction have important ecological implications. The toxic and HAB-forming dinoflagellate,Pheopolykrikoides hartmannii has been previously reported to be heterothallic. Here,we provide visual confirmation of homothally of P. hartmannii and the first detailed visual recording of cyst germination based on the observations of a clonal isolate from Jiaozhou Bay,China. To document the homothallism,we first observed cell pairs in sexual mating,planozygotes with two longitudinal flagella,and cysts with typical morphology as described previously from the clonal culture. We then germinated a single cyst,established a new clonal culture from one of the two daughter cells after the first cell division of the germling (i.e. from the diploid germling to two haploid cells),and produced cysts again from the newly established clonal culture. For the observation of the germination time-series,we took micrographs and videos to show all germination processes,particularly with an interesting observation of the short amoeboid stage of the germling releasing from the archeopyle (~15 s),which was a landmark of the germination process and has not been reported elsewhere. This definitive evidence of homothallic sexuality and cyst production in P. hartmannii provides a new insight into the biology and ecology of the species,particularly a mechanism that may partly account for the population dynamics and ubiquitous distribution of the species.Keywords：germination;harmful algal blooms (HABs);heterothallism;homothallism;resting cyst;Pheopolykrikos hartmannii4|0|0Updated：2023-04-27
- Abstract：In the coastal ecosystems of the Black Sea, macrophytobenthos and, in particular, the association of Cystoseira crinite, C. barbata, Cladostephus verticillatus, and Corallina mediterranea, with its thick vegetative canopy (VC), is the key contributor to primary production (PP). Though the vertical structure of the canopy, formed by the algal association, is of principal importance to the PP level, this subject has been long-neglected by researchers. The goal of our work was to compare vertical structures of the vegetative canopy of Cystoseira brown algae under diverse hydrodynamical conditions of the Crimean Peninsula coast. Samples were collected using the 50 cm×50 cm counting frame at eight stations positioned in shallow (55-60 cm deep) sites of Sevastopol Bay (Crimean Peninsula). Dry weight biomass of the VC was determined for all algae assemblage and for each algal species individually, per horizontal surface unit, at each height (Z). The study shows that:1) the VC is characterized by unimodal vertical distribution of biomass, with maximum estimate in the lower part, where the biomass increases to 85% of the total biomass; 2) a series of single-peaked curves reliably describes the unimodal distribution of the biomass; thalli of different age groups are found along the canopy profile; and 3) algae found in epiphytic synusia prefer inhabiting the upper part of the VC. The role of environmental factors (seawater turbulence and solar radiation) is discussed in reference to the formation of the vertical structure, made up of the associations of the brown algae Cystoseira.Keywords：vertical structure of the canopy;phytobenthos;phytocenosis;Cystoseira;epiphyte;biomass;multicellular algae;Black Sea4|3|0Updated：2023-04-27
- Abstract：Aurelia coerulea polyp is an important stage in the outbreaks of this species. To test the combined effects of salinity and temperature on the survival and asexual reproduction of polyps,we maintained 864 polyps at various salinities (15,25,33,and 40) and temperatures (9,12,15,18,21,and 24℃). Polyps could mostly survive in all treatment combinations except in salinity 15 treatments with low temperatures (9-15℃). Budding occurred at all temperatures (9-24℃),while strobilation only occurred at the low temperatures (9-15℃). The range of 12-15℃ was suitable for strobilation and ephyrae release. The optimal range of salinity for asexual reproduction was 25-33. Low (15) or high (40) salinity could significantly reduce the numbers of new buds or ephyrae,and low salinity of 15 retarded and even prevented strobilation at low temperatures. The optimal treatment for budding and strobilation was 21℃-salinity 25 and 12℃-salinity 33,respectively. Salinity had less of an impact than temperature on asexual reproduction,except for the polyps in high or low osmotic pressure conditions.Keywords：Aurelia coerulea;polyp;temperature;salinity;asexual reproduction4|0|2Updated：2023-04-27
- Abstract：Polychaetes are one of the most important groups of macrobenthic organisms in coastal and marine environments, in terms of diversity and abundance, and play an important role in the functioning of ecosystem. This study aims to describe the structure and spatial distribution of polychaete communities along Essaouira's rocky shoreline (Atlantic coast of Morocco) in relation to the major environmental variables such as granulometry, salinity, temperature, pH, and intertidal range. Twelve sites from these intertidal rocky shores were sampled using a quadrat method during the summer 2016. A total of 4 435 individuals belonging to 34 taxa were recorded. Among the families, Sabellaridae (24%) and Nereididae (23%) were ranked first in terms of abundance of individuals. Sabellaria alveolata (24%) and Perinereis cultrifera (13%) were the dominant species. Diversity (H') values varied from 2.28 to 3.95. Pielou's index (J') varied between 0.62 and 0.89. This was essentially due to the low dominance of few species. Cluster analysis was used to characterise Essaouira's rocky shores on the basis of benthic polychaete communities. SIMPER analysis confirmed the presence of three distinct communities. According to canonical correspondence analysis, the structure and distribution of faunal assemblages of benthic polychaetes was mainly related to topographical complexity, water temperature, hydrodynamic conditions and upwelling. We conclude that these rocky shores show typically high benthic polychaete diversity compared to the taxonomic list of other rocky coasts. In addition, these results constitute a baseline data for the development of a sustainable network for long-term monitoring of benthic polychaete community changes due to ecological factor influences and anthropogenic activity impacts.Keywords：polychaetes;taxonomic diversity;Essaouira;rocky shore;faunal assemblage4|6|0Updated：2023-04-27
- Abstract：Although the taxonomy of oligotrich ciliates has been widely investigated, yet the species diversity remains poorly known. We newly designed a pair of oligotrich-specific LSU rDNA primers covering the 600-bp D1/D2 region, and it was effective for detecting oligotrich species. Using the primers, we constructed the cloning libraries to investigate the species diversity of oligotrichs in the northern coastal waters of the South China Sea. In total, 165 oligotrich sequences were obtained from five widely separated sampling sites. Sixty operational taxonomic units (OTUs) were obtained at 99% similarity threshold, and low-abundance OTUs with no more than two sequences contributed most of these (about 78%). Our findings are consistent with previous morphological studies, Strombidium was found the most abundant and widely distributed genus in this area. In addition, the BLAST search in the NCBI database resulted in 95% OTUs matching with named oligotrich species in similarity below 99%. Therefore, oligotrich morphospecies diversity has been underestimated as low-abundance species, and the LSU rDNA oligotrich sequence database needs to be better promoted.Keywords：diversity;low-abundance species;oligotrich ciliates;operational taxonomic units (OTUs)4|2|1Updated：2023-04-27
- Abstract：Pseudoalteromonas marina is one of the potential pathogens that cause green spot disease (GSD) in Pyropia yezoensis. To prevent GSD from development and spread, an effective method to detect the pathogen at early GSD infection stages need to be established. In this research, PCR methods were established targeting the dnaA gene (encoding chromosome replication initiator protein) and the dnaN gene (encoding β sliding clamp of DNA polymerase Ⅲ protein) to detect P. marina with three primer pairs pws-dnaA2 (Forward, 5'-ACCGCATTAACGAACTACTCGTG-3'; Reverse, 5'-TGCCATTACCTACAGCATGG-3'), pcs-dnaN2 (Forward, 5'-CTTACAACGTTATCAGCGGC-3'; Reverse, 5'-GTTGAGTATTAAGTGATTGAGTAAGC-3') or pws-dnaN3 (Forward, 5'-ACTTACAACGTTATCAGCGGC-3'; Reverse, 5'-ACTGCTGTTTGAGTCTGCTAAC-3'). Three PCR methods corresponding to the three primer pairs sufficiently distinguished P. marina from 22 bacterial species, thus resulting in detection limits of 4 to 4×102 CFU cells or 2.37×101 to 2.37×103 fg of P. marina DNA per PCR reaction. In an artificial infection experiment of P. yezoensis infected with P. marina, all established PCRs successfully detected P. marina at early GSD infection stages. The results show that the established PCRs are specific and sensitive, and are potential for applications in early diagnosis of GSD in Pyropia.Keywords：Pyropia yezoensis;green spot disease (GSD);Pseudoalteromonas marina;PCR detection;early diagnosis4|0|0Updated：2023-04-27
- Abstract：The quality of light is an important abiotic factor that affects the growth and development of photosynthetic organisms. In this study, we exposed the unicellular green alga Dunaliella salina to red (660 nm) and blue (450 nm) light and analyzed the cell growth, total carotenoid content, and transcriptomes. The growth of D. salina was enhanced by illumination with red light, whereas blue light was not able to promote the algal growth. In contrast, the total carotenoid content increased under both red and blue light. The RNA of D. salina was sequenced and the transcriptomic response of algal cells to red and blue light was investigated. Six transcripts encoding for the blue light receptor cryptochrome were identified, and transcripts involved in the carotenoid metabolism were up-regulated under both red and blue light. Transcripts encoding for photoprotective enzymes related to the scavenging of reactive oxygen species were up-regulated under blue light. The present transcriptomic study provides a more comprehensive understanding of carotenoid biosynthesis in D. salina under different wavelengths of light.Keywords：blue light;carotenoid;Dunaliella;red light;transcriptome4|0|5Updated：2023-04-27
Ecology
- Abstract：Chlorella pyrenoidosa (Chlorophyceae) is widely cultured for production of health food and animal feed. In outdoors, mass cultivation of C. pyrenoidosa often suffers from high temperature. A better understanding of the effects of high temperature on photosynthesis and photoprotection can help optimize the productivity of C. pyrenoidosa cultures. In this study, we investigated effect of high temperature (35, 38, or 41℃) on the balance between photosynthetic light absorption and energy utilization of C. pyrenoidosa. In contrast to 30℃, higher temperature of 35 or 38℃ did not inhibit the growth of C. pyrenoidosa. Treatment in 35℃ maintained the balance. Moreover, the PSI acceptor side in 38℃ was over-reduced and PSII reaction centers were over-excited under strong light, which destroyed the balance and generated active oxygen species (AOS). However, the activated antioxidant enzymes might remove completely the over-production of AOS, thereby protect C. pyrenoidosa cells from photodamage. It shows that this C. pyrenoidosa strain could tolerate as high as 38℃. Furthermore, treatment in 41℃ resulted in more lack of the balance than that in 38℃. However, the activities of antioxidant enzymes stopped increasing in 41℃, and were not strong enough to remove the excess AOS. Therefore, treatment in 41℃ could decrease the growth of C. pyrenoidosa. In addition, strong and longtime light exposure would cause serious photodamage to C. pyrenoidosa cells.Keywords：antioxidant enzyme;Calvin cycle;high temperature tolerance;photoprotection;photosynthesis;Chlorella pyrenoidosa4|0|2Updated：2023-04-27
- Abstract：Halomonas sp. YSR-3 was isolated from the Yellow Sea and identified as a polyphosphateaccumulating bacterium and the characteristics of its intracellular polyphosphate (polyP) granules and phosphorus absorption were studied. Most YSR-3 cells stored one or two polyP granules in regular appearance and high-density. The diameter of the granules was about 400 nm measuring by a transmission electron microscope (TEM). After stained with 4, 6-diamidino-2-phenylindole (DAPI) and visualized by a fluorescence microscope, the cells turned blue and the granules were bright yellow. The composition of granules includes P (major ingredient), Mg, S, K, and Ca as detected by an energy dispersive X-ray spectrometer (EDS). When inorganic phosphorus (PO43-) and ferric ion (Fe3+) were added into media, the biomass increased and the cells formed intracellular polyP granules owing to the phosphorus assimilation from media. The YSR-3 obtained higher biomass by adding 0.02 g/L FePO4 than 0.005 g/L and 0.01 g/L FePO4; however, the phosphorus absorption was higher with 0.01 g/L FePO4 than 0.005 g/L and 0.02 g/L FePO4. The optical density at wavelength 480 nm (OD480 nm) was 0.79 and 100% cells could form intracellular polyP granules. These results show that strain YSR-3 is able to acquire higher biomass and absorb more inorganic phosphorus when 0.01 g/L FePO4 is added. The characteristics of absorbing and storing phosphorus as intracellular inorganic polyP granules have a potential for application in high-efficiency phosphorus removal in wastewater treatment.Keywords：polyphosphate-accumulating bacterium;polyphosphate granule;Halomonas;enhanced biological phosphorus removal4|0|0Updated：2023-04-27
- Abstract：The live-bearing genus Sebastes is renowned for its outstanding species richness and color diversity, and its speciation has been a point of interest. This study investigated the age, growth, reproductive biology, color pattern and ontogenetic divergence of a pair of closely related rockfishes from the coasts of the Shandong Peninsula, namely, Sebastes koreanus (n=879) and S. nudus (n=257). Marginal increment analysis of sectioned otoliths showed that annulus formation occurred once a year between June and July in both species. The sex-pooled growth curves of S. nudus and 3 populations of S. koreanus differed significantly from each other. No apparent latitudinal cline in growth parameters was found in S. koreanus. For both species, the peak parturition periods were from April to May, and the peak copulation periods were from November to December. S. nudus has a highly variable and conspicuous color pattern while S. koreanus has a stable and dull color pattern. This difference, together with the overlapping distribution and the close relationship, make S. koreanus and S. nudus an ideal model to investigate the color-driven speciation of the Sebastes. We confirmed that S. nudus changes its body color with age and season and fully expresses the carotenoid-based nuptial coloration when the fish reaches first maturity. Moreover, our comparisons of morphological traits that are likely related to survival and quality of these fishes suggested that S. nudus may suffer higher predation risk and foraging difficulty beginning at age 3. In light of the ontogenetic development of the color pattern in S. nudus, we suggested that the full expression of nuptial coloration most likely triggers the strong selective pressure to enhance swimming performance, anti-predator defense and foraging capacity of S. nudus through predator-prey interactions. By understanding all these details, we further inferred a hypothesis that both color pattern and bathymetric segregation play key roles in facilitating the speciation of demersal rockfishes.Keywords：Sebastes;growth;color pattern;speciation4|0|0Updated：2023-04-27
- Abstract：At present, the function and profile of long noncoding RNAs (lncRNAs) in half-smooth tongue soles Cynoglossus semilaevis remain poorly understood. Therefore, we identified lncRNAs in the species using large-scale deep sequencing approaches. A total of 96 726 222 clean reads and 2497 lncRNAs were obtained from the compound samples. In total, 1 694 known lncRNAs and 803 novel lncRNAs were identified. Most of the novel lncRNAs distributed mainly in a range of 200-3 000 nt and contained 2-6 exons. Six novel lncRNAs were selected for expression analysis by quantitative reverse transcription-polymerase chain reaction, of which lnc_770 and lnc_150 were expressed mainly in the ovary. This study provides a valuable resource for lncRNA studies of half-smooth tongue sole and improves our understanding of the function of non-coding RNA in fish.Keywords：Cynoglossus semilaevis;long noncoding RNAs (lncRNAs);expression profiles4|0|0Updated：2023-04-27
Biology
- Abstract：Although the impact of ocean acidification on marine bivalves has been previously investigated under mainly controlled laboratory conditions, it is still unclear whether the impact of acidification on sediment-burrowing species differs between those within or without sediment. In order to fill this gap in our knowledge, we compared shell properties of the infaunal Manila clam (Ruditapes philippinarum) exposed to three pH concentrations (7.4, 7.7, and 8.0), within and without sediments. In the first experiment (140 d), clams were exposed to seawater in an acidification system without sediment. A decrease in shell weight corresponding to the increase in dissolution rate was observed in the group of pH 7.4, at which shell color disappeared or whitened. SEM observations confirmed the changes of the external shell surface. In the second experiment (170 d), sediment was placed at the bottom of each exposure chamber. The effects were found obvious in shell dissolution rate and shell color in the shell specimens exposed to overlying seawater but not found in the shell specimens exposed to sediment. Although the experimental period was longer in the second experiment, shell specimens in the first experiment were more seriously damaged than those in the second experiment under acidic seawater conditions. Our results, in relation to the defense function of the shell, show that marine bivalves in burrowing behavior are more adaptable to seawater acidification than those who do not burrow into sediment.Keywords：ocean acidification;sediment;Manila clam (Ruditapes philippinarum);shell properties4|0|0Updated：2023-04-27
- Abstract：The rapa whelk Rapana venosa transforms from a phytophagous larva to a carnivorous juvenile after settlement and metamorphosis. The high mortality rate and low metamorphosis rate (< 1%) of larvae are among the key factors limiting the recovery of the resources of R. venosa. We studied these two processes and showed that the larva has the ability to settle and metamorphose in the middle and late 4 spiral whorl period,and the use of substrates (scallop shells with oysters) can significantly improve the settlement and metamorphosis rate of larvae. The presence of darkness,juvenile bivalve shellfish,and oyster polysaccharide could effectively increase the rates of larval settlement and metamorphosis. Our findings broaden the understanding of settlement and metamorphosis in gastropods and can be used to improve population control,resource recovery and commercial breeding strategies for R. venosa.Keywords：larval development;substrate;oyster polysaccharide;commercial breeding4|2|0Updated：2023-04-27
- Abstract：The structure of intestinal microbiota of black rockfish Sebastes schlegelii in five early development stages were determined in high throughput sequencing with Illumina MiSeq PE300 system. The relationship between intestinal microbial community and the environmental (including culture water and feed) microbiota and the abundance variation trends of core microbiota were investigated,based on which the source of some core microbiota was analyzed in this study. The results show that Proteobacteria and Firmicutes are the most dominant phyla in guts. At the genus level,there are obvious differences between the artificial breeding fish and wild adults in the intestinal microflora structure. The compositions of dominant genera are similar,although the structure of intestinal microbiota gradually changes with the growth of larvae and juveniles. The core microbiota including Bacillus, Acinetobacter, Pseudomonas, Lactobacillus, Lactococcus, Glaciecola, Vibrio, Pseudoalteromonas, Acidovorax, and Aliivibrio were determined in the analysis of dominant and shared species. Compared with the water,the effect of feed microbiota on the structure of the gut microbial community is more obvious. Moreover,the trends of Bacillus, Acinetobacter, Pseudomonas, Lactobacillus, Lactococcus, and Glaciecola were opposite to Vibrio and Pseudoalteromonas in the gut. The correlation analysis suggested that Acidovorax, Glaciecola, Pseudomonas, Lactobacillus, and Acinetobacter might transited from mainly the parents and/or came from the fertilization process. The relative results may provide a theoretical reference for selecting the native probiotics,and supply the basic data for artificially regulating the intestinal microbiota with probiotic during early developmental stage of black rockfish.Keywords：core microbiota;correlation analysis;intestinal microbiota;larva and juvenile;microbiota structure;Sebastes schlegelii4|0|2Updated：2023-04-27
- Abstract：Tetraploid fish are important for mass production of triploids in polyploid breeding. In this study,we reported a novel protocol for artificial induction of tetraploidy by a combination of cold shock and hydrostatic pressure administered to gynogenetically developed eggs in Japanese flounder Paralichthys olivaceus. The induction was carried out by activating the eggs with UV-irradiated sperm of red sea bream Pagrus major,administering a cold shock (0℃,5 to 45 min) 3 min after fertilization to inhibit second polar body exclusion,incubating the eggs for 60 min at 17℃,and treating them with a 650 kg/cm2 hydrostatics pressure shock for 6 min. We named the embryos gyno-tetraploids that developed from eggs after such treatments. The hatching rate of the gyno-tetraploids ranged from 20.99%±3.66% to 36.01%±2.79%,and the tetraploid rate ranged from 80.00% to 100.00%. All-maternal inheritance was verified using 6 high-recombination-rate microsatellite markers. This method successfully induced gyno-tetraploidy. The successful induction of gyno-tetraploidy lays the foundation for triploidization of new varieties with improved economic traits of interest that can benefit commercial culture.Keywords：gynogenesis;polyploidy;chromosome manipulation;mosaic4|3|0Updated：2023-04-27
- Abstract：The transient receptor potential vanilloid 4 (TRPV4),another Ca2+ entry channel,belongs to the vanilloid subfamily and responds to a number of different physical and chemical stimuli and exists widely in mammals. However,our understanding of the TRPV4 in fish remains poor. Therefore,we studied the TRPV4 gene from Cynoglossus semilaevis,named CsTRPV4 that encodes a putative protein of 870 amino acids common in structure and characteristic of mammalian TRPV4,including the domains of ANK repeats,six TM,TRP domain,and CaMBD. The CsTRPV4 was expressed ubiquitously in examined tissues:higher expression in the heart,spleen,testis,and eye,but lower expression in kidney and liver. Surprisingly,the expression of CsTRPV4 in lateral line was significantly higher than in many other tissues as the CsTRPV4 was expressed significantly in the free neuromasts. In addition,CsTRPV4 in the free neuromast from the larval fish was significantly expressed in the hair cells of the free neuromasts. Therefore,the free neuromasts can act as a mechano-sensor to the mechanical stimulation in molecular level in C. semilaevis,which lays a foundation for further study of the functions of the free neuromasts.Keywords：transient receptor potential vanilloid 4 (TRPV4);Cynoglossus semilaevis;gene expression;free neuromasts;in situ hybridization4|0|0Updated：2023-04-27
Aquaculture and Fisheries
- Abstract：To fill the blank in systematic study on the organoleptic quality of large yellow croaker Larimichthys crocea,we analyzed the organoleptic quality of the fish meat of wild,trash-fish-fed,and compound-feed-fed large yellow croaker. Six fish (weight:500 g) per group were sampled in the same period,and 89 indices of fish organoleptic quality were measured and analyzed. Results reveal significant differences in the body condition factor,skin/muscle color,flesh texture,odor,and taste aspects between wild and farmed fish. Compared with the wild fish,farmed fish showed fatter body shape,whiter skin or muscle color,tender muscle,higher level of fishy odor or volatile intensity,but lower delicious taste. In addition,compared with trash-fish feeding,compound-feed feeding could improve the body shape,skin color,flesh texture,and fish taste of large yellow croaker,but it also increased the fishy odor. In principle component analysis and cluster analysis,the present study preliminarily established the systematic evaluation with multiple indices to the quality of large yellow croaker. It shall be helpful for the evaluation or improvement of the quality of farmed large yellow croaker.Keywords：large yellow croaker;appearance;texture;odor;taste4|4|6Updated：2023-04-27
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