Heavy precipitation and extreme drought have caused severe economic losses over South China and Indochina(INCSC)in recent decades.Given the areas with large gross domestic product(GDP)in the INCSC region are distribut...Heavy precipitation and extreme drought have caused severe economic losses over South China and Indochina(INCSC)in recent decades.Given the areas with large gross domestic product(GDP)in the INCSC region are distributed along the coastline and greatly affected by global warming,understanding the possible economic impacts induced by future changes in the maximum consecutive 5-day precipitation(RX5day)and the maximum consecutive dry days(CDD)is critical for adaptation planning in this region.Based on the latest data released by phase 6 of the Coupled Model Intercomparison Project(CMIP6),future projections of precipitation extremes with bias correction and their impacts on GDP over the INCSC region under the fossil-fueled development Shared Socioeconomic Pathway(SSP5-8.5)are investigated.Results indicate that RX5day will intensify robustly throughout the INCSC region,while CDD will lengthen in most regions under global warming.The changes in climate consistently dominate the effect on GDP over the INCSC region,rather than the change of GDP.If only considering the effect of climate change on GDP,the changes in precipitation extremes bring a larger impact on the economy in the future to the provinces of Hunan,Jiangxi,Fujian,Guangdong,and Hainan in South China,as well as the Malay Peninsula and southern Cambodia in Indochina.Thus,timely regional adaptation strategies are urgent for these regions.Moreover,from the sub-regional average viewpoint,over two thirds of CMIP6 models agree that maintaining a lower global warming level will reduce the economic impacts from heavy precipitation over the INCSC region.展开更多
The inland saltwater lakes harbor exceptional biodiversity.Here,two new species of solitary sessile peritrich ciliates were isolated from Qinghai Lake,the largest inland saltwater lake in China.Their morphology,ciliat...The inland saltwater lakes harbor exceptional biodiversity.Here,two new species of solitary sessile peritrich ciliates were isolated from Qinghai Lake,the largest inland saltwater lake in China.Their morphology,ciliature,silverline system,and molecular phylogeny were investigated based on live observation,silver staining,and analysis of the small subunit ribosomal DNA(SSU rDNA).Vorticella paraglobosa sp.n.is characterized mainly by its obconical or elongate bell-shaped zooid,C-shaped macronucleus,single ventrally located contractile vacuole,two-rowed infundibular polykinety 3,and 28-38 silverlines between peristome and aboral tro-chal band and 10-15 between aboral trochal band and scopula.Vorticella cotyliformis sp.n.differs from its congeners mainly by its double-layered peristomial lip,cup-shaped zooid,J-shaped macronucleus,single ventrally positioned contractile vacuole,three-rowed infundibular polykinety 3,and 70-85 silverlines between peristome and aboral trochal band and 21-25 between aboral trochal band and scopula.The SSU rDNA sequences of the two new species were obtained,and the subsequent molecular phylogenetic analysis supported their taxonomic classification.展开更多
Climate change, resulting from human-caused CO_(2) and other greenhouse gas emissions, is an urgent problem that demands immediate action from everyone. The need to decrease emissions has sparked a renewed emphasis on...Climate change, resulting from human-caused CO_(2) and other greenhouse gas emissions, is an urgent problem that demands immediate action from everyone. The need to decrease emissions has sparked a renewed emphasis on developing and utilizing offshore Carbon Capture,Utilization,and Storage(CCUS) technologies.While these technologies offer potential solutions to mitigate greenhouse gas emissions,many challenges must be addressed to ensure successful implementation.展开更多
The Agulhas system is the strongest western boundary current system in the Southern Hemisphere and plays an important role in modulating the Indian-to-Atlantic Ocean water exchange by the Agulhas leakage.It is difficu...The Agulhas system is the strongest western boundary current system in the Southern Hemisphere and plays an important role in modulating the Indian-to-Atlantic Ocean water exchange by the Agulhas leakage.It is difficult to measure in situ transport of the Agulhas leakage as well as the Agulhas retroflection position due to their intermittent nature.In this study,an innovative kinematic algorithm was designed and applied to the gridded altimeter observational data,to ascertain the longitudinal position of Agulhas retroflection,the stability of Agulhas jet stream,as well as its strength.The results show that the east-west shift of retroflection is related neither to the strength of Agulhas current nor to its stability.Further analysis uncovers the connection between the westward extension of Agulhas jet stream and an anomalous cyclonic circulation at its northern side,which is likely attributed to the local wind stress curl anomaly.To confirm the effect of local wind forcing on the east-west shift of retroflection,numerical sensitivity experiments were conducted.The results show that the local wind stress can induce a similar longitudinal shift of the retroflection as altimetry observations.Further statistical and case study indicates that whether an Agulhas ring can continuously migrate westward to the Atlantic Ocean or re-merge into the main flow depends on the retroflection position.Therefore,the westward retroflection may contribute to a stronger Agulhas leakage than the eastward retroflection.展开更多
Harmful algal blooms(HABs) have led to extensive ecological and environmental issues and huge economic losses.Various HAB control techniques have been developed,and biological methods have been paid more attention.Alg...Harmful algal blooms(HABs) have led to extensive ecological and environmental issues and huge economic losses.Various HAB control techniques have been developed,and biological methods have been paid more attention.Algicidal bacteria is a general designation for bacteria which inhibit algal growth in a direct or indirect manner,and kill or damage the algal cells.A metabolite which is strongly toxic to the dinoflagellate Alexandrium tamarense was produced by strain DH46 of the alga-lysing bacterium Alteromonas sp.The culture conditions were optimized using a single-factor test method.Factors including carbon source,nitrogen source,temperature,initial pH value,rotational speed and salinity were studied.The results showed that the cultivation of the bacteria at 28℃ and 180 r min-1with initial pH 7 and 30 salt contcentration favored both the cell growth and the lysing effect of strain DH46.The optimal medium composition for strain DH46 was determined by means of uniform design experimentation,and the most important components influencing the cell density were tryptone,yeast extract,soluble starch,NaNO3 and MgSO4.When the following culture medium was used(tryptone 14.0g,yeast extract 1.63g,soluble starch 5.0 g,NaNO3 1.6 g,MgSO4 2.3 g in 1L),the largest bacterial dry weight(7.36 g L-1) was obtained,which was an enhancement of 107% compared to the initial medium;and the algal lysis rate was as high as 98.4% which increased nearly 10% after optimization.展开更多
Dark respiration （non-photorespiratory mitochondrial respiration）, which occurs both in the light and in darkness, is vital for growth and survival of algae and plays a critical role in modulating the carbon balance...Dark respiration （non-photorespiratory mitochondrial respiration）, which occurs both in the light and in darkness, is vital for growth and survival of algae and plays a critical role in modulating the carbon balance of them. In the present study, we have investigated dark respiration in the light （RL） and in darkness （RD） in three marine macroalgal species, Hizikia fusiformis （phaeophyta）, Gracilaria lemaneiformis （Rhodophyta） and Ulva lactuca （Chlorophyta）, cultured at 20 ℃ using aeration with two CO2 conditions： current ambient （CO2 concentration about 380 μl/L） and elevated CO2 （approximately 720 μl/L） air. RL was estimated by using the Kok method, whereas RD was determined as the rate of O2 influx at zero light. The results showed that both RL and RD were unchanged for the elevated CO2-grown algae relative to ambient CO2 concentration for all the algal species tested. However, RL was significantly lower than RD across all the algal species and growth CO2 treatments, demonstrating that daytime respiration was partly depressed by the light. The percentage of inhibition of respiration by light was similar between ambient and elevated CO2- grown algae. The ratio of respiration to photosynthesis, which tended to decrease when estimated using RL instead of RD, was not altered for the elevated relative to ambient CO2 concentration. The results suggest that RL, rather than RD, is a more accurate estimate of nonphotorespiratory carbon loss in marine macroalgae during the daytime. It would not be anticipated that elevated atmospheric CO2 would exert a substantial influence on respiratory flux either in the light or in darkness in these particular marine macroalgal species.展开更多
Ecological experiments were conducted to examine the effects of seawater containing elevated par- tial pressure of carbon dioxide （p CO2 800 × 10 -6 , 2 000 × 10 -6 , 5 000 × 10 -6 and 10 000 × 10...Ecological experiments were conducted to examine the effects of seawater containing elevated par- tial pressure of carbon dioxide （p CO2 800 × 10 -6 , 2 000 × 10 -6 , 5 000 × 10 -6 and 10 000 × 10 -6 ） on the survival and reproduction of female Acartia pacifica, Acartia spinicauda, Calanus sinicus and Centropages tenuiremis, which are the dominant copepods in the southern coastal waters of China. The results show that the effects of elevated p CO2 on the survival rates of copepods were species-specific. C. sinicus, which was a macro-copepod, had a higher survival rate （62.01%–71.96%） than the other three species （5.00%–26.67%） during the eight day exposure. The egg production rates of C. sinicus, A. spinicauda and C. tenuiremis were significantly inhibited by the increased p CO2 and the exposure time duration. There were significantly negative impacts on the egg hatching success of A. spinicauda and C. tenuiremis in the p CO2 2 000 × 10 -6 and 10 000 × 10 -6 groups, and, in addition, the exposure time had noticeably impacts on these rates too. This study indicates that the reproductive performances of copepods were sensitive to elevated p CO2 , and that the response of different copepod species to acidified seawater was different. Furthermore, the synergistic effects of seawater acidification and climate change or other pollutant stresses on organisms should be given more attention.展开更多
The coastal ecosystems are highly sensitive to climate change and are usually influenced by variations in phytoplankton communities and water physiochemical factors.In the present study,the phytoplankton community,chl...The coastal ecosystems are highly sensitive to climate change and are usually influenced by variations in phytoplankton communities and water physiochemical factors.In the present study,the phytoplankton community,chlorophyll a(Chl a)and their relationships with environmental variables and dimethylsulfide(DMS)and dimethylsulfoniopropionate(DMSP)were investigated in spring 2017(March 24 to April 16)in the East China Sea(26.0°-33.0°N,120.0°-128.0°E)and southern Yellow Sea(31.0°-36.0°N,120.0°-125.0°E).The spatial distributions of phytoplankton species composition and cell density were investigated by qualitative and quantitative methods and were compared with historical data to study phytoplankton species succession in the survey area.The results showed that there were 275 phytoplankton species belonging to 90 genera and 6 phyla in the survey area,of which 208 species belonged to 62 genera of Bacillariophyta and 56 species belonged to 20 genera of Pyrrophyta.The dominant phytoplankton species were Skeletonema dohrnii,Chaetoceros vanheurckii and Prorocentrum donghaiense.The phytoplankton cell densities ranged from 0.06×10^(4)cells/L to 418.73×10^(4)cells/L,with an average value of 21.46×10^(4)cells/L.In spring,the average ratio of Bacillariophyta/Pyrrophyta was41.13 for the entire study area.The areas with high phytoplankton cell density were mainly distributed in the northern South Yellow Sea and offshore waters of the East China Sea.According to a canonical correspondence analysis among phytoplankton and environmental parameters,the water Chl a concentrations were notably consistent with phytoplankton cell density(P<0.001),and both showed significant negative correlations with salinity and nitrite(P<0.05)and significant positive correlations with dissolved oxygen and pH(P<0.001).There was a significant positive correlation between diatom(both in cell density and in dominant species)and DMS(P<0.05),which indicated that diatoms play a greater role in DMS production in this investigated area.展开更多
The authors have investigated the biochemical events by which marine algal virus infection induces cell cycle arrest. The key G 2 /M-phase regulatory proteins are analyzed by immunobloting in unicel-lular Emiliania hu...The authors have investigated the biochemical events by which marine algal virus infection induces cell cycle arrest. The key G 2 /M-phase regulatory proteins are analyzed by immunobloting in unicel-lular Emiliania huxleyi,suggesting that virus induced cell cycle arrest is related with virus＇s effect on cyclins and cyclin dependent kinases. E. huxleyi virus（EhV） represses Cdc2/cyclinB complex activity by inhibiting the activity of Cdc2 kinase in a phosphorylation-related manner,blocking host cells G 2 /M checkpoint. Dephosphorylated /inactive Cdc25C combined with up-regulation of Wee1 expression at early infect period appears to be important mechanisms by which EhV represses Cdc2/cyclinB complex activity that is required for entry into M phase. This study has allowed us to confirm that algal virus infection leads to selective activation or inhibition of certain cell-cycle factors,which may play a significant role in establishing a more efficient environment for viral gene expression and DNA replication.展开更多
The performance and integrity of a cassette cross-flow ultrafilter （Pellicon 2, Millipore） are examined with a suite of macromolecules of different molecular masses. The retention coefficient during the cross-flow u...The performance and integrity of a cassette cross-flow ultrafilter （Pellicon 2, Millipore） are examined with a suite of macromolecules of different molecular masses. The retention coefficient during the cross-flow ultrafiltration experiments increases with increasing molecular mass and reaches 90% with 10 kDa dextran in both milli-Q water and ultrafiltered seawater media. Based on a 90% retention coefficient, the molecular mass cut-off for the ultrafiltration membrane is defined at 10 kDa, which is ten times （1 kDa） that rated by the manufacturer. To further validate the accuracy of the laboratory calibration, the samples from the lower Zhujiang River and the Jiulong River Estuary are ultrafiltered with the cassette ultrafiltration membrane and the colloidal organic carbon abundances in these samples are quantified with the ultrafiltration per- meation model based on time series permeation subsamples. The colloidal organic carbon abundances are 5.8%-21.1% in the Jiulong River Estuary and 5.6%-11.0% in the lower Zhujiang River. These are consistent with the reported values for both estuaries as well as with the colloidal organic carbon abundances in ma- rine environments over the coastal and open oceans with 10 kDa cut-off membranes. Therefore, these field data support the laboratory calibration result and indicate the validity of the experimental and quantification procedure adopted. The discrepancy between the nominal molecular mass cut-off and the actual pore size of the ultrafiltration membrane should be of great concern for research in colloidal and nanoparticle biogeochemistry. Careflfl examination of the membrane integrity should be taken during ultrafiltration ex- oeriments in order to avoid misleading molecular mass cut-off information.展开更多
Toxic and harmful algal blooms are usually more frequent in mariculture areas due to the abundant trophic conditions.To investigate the relationship between toxic and harmful microalgae and environmental factors,we se...Toxic and harmful algal blooms are usually more frequent in mariculture areas due to the abundant trophic conditions.To investigate the relationship between toxic and harmful microalgae and environmental factors,we set up 12 stations near three mariculture regions(Gouqi Island,Sandu Bay,and Dongshan Bay)in the East China Sea.We collected samples from all four seasons starting from May 2020 to March 2021.We identifi ed 199 species belonging to 70 genera,of which 38 species were toxic and harmful,including 24 species of Dinophyceae,13 species of Bacillariophyceae,and 1 species of Raphidophyceae.The species composition of toxic and harmful microalgae showed a predominance of diatoms in the summer(August),and dinofl agellates in the spring(May),autumn(November),and winter(March).The cell densities of toxic and harmful microalgae were higher in summer(with an average value of 15.34×10^(3) cells/L)than in other seasons,3.53×10^(3) cells/L in spring,1.82×10^(3) cells/L in winter,and 1.0×10^(3) cells/L in autumn.Pseudo-nitzschia pungens,Prorocentrum minimum,Paralia sulcata,and Prorocentrum micans were the dominant species and were available at all 12 stations in the three mariculture areas.We selected 10 toxic and harmful microalgal species with frequency>6 at the survey stations for the redundancy analysis(RDA),and the results show that NO^(-)_(3),water temperature(WT),pH,DO,and NO^(-)_(2) were the main factors on distribution of toxic and harmful microalgae.We concluded that the rich nutrient conditions in the East China Sea mariculture areas increased the potential for the risk of toxic and harmful microalgal bloom outbreaks.展开更多
anoxygenic phototrophic bacteria （AAPB）, which form a unique functional group of heterotrophic bacteria, have the abilit,to utilize light energy. The impact of carbon source and light intensity on the growth and bac...anoxygenic phototrophic bacteria （AAPB）, which form a unique functional group of heterotrophic bacteria, have the abilit,to utilize light energy. The impact of carbon source and light intensity on the growth and bacteriochlorophyn a （ BChl a） expression of a typical strain of AAPB, Erythrobacter longus strain DSMZ6997 was examined during batch culture and continuous culture. The results showed that the expression of BChl a in DSMZ6997 was regulated by both carbon-source and light conditions, and was stimulated by low availability of carbon but inhibited by light to a certain extent at 300 lx and completely at 1 500 lx. In contrast, cell abundance, and even cell size of this strain, was substantially enhanced under light/dark cycle cultivation conditions over dark conditions, indicating the promotion of growth by light. These results led to the conclusion that utilization of light through BChl a helps AAPB to survive under carbon stress, while light at high intensity is harmful to the synthesis of BChl a in AAPB.展开更多
Metallothioneins(MTs) are normally considered to be sensitive indicators of heavy metal pollution, but it is less clear whether the MT gene can actively respond to other environmental stresses. In this study, an MT m ...Metallothioneins(MTs) are normally considered to be sensitive indicators of heavy metal pollution, but it is less clear whether the MT gene can actively respond to other environmental stresses. In this study, an MT m RNA molecular sequence of 471 bp(full length) was identified in marine cultured black porgy(Acanthopagrus schlegelii), encoding 60 amino acids containing 20 cysteine residues. The MT sequence was highly homologous to that of other fish belonging to the MT superfamily type 1 family. The three dimensional structure of the deduced MT peptide was composed of two metal-binding domains capable of ligating divalent heavy metals. The MT m RNA transcripts were detected in the 11 tested tissues and the highest quantity was present in the liver. Stresses by two factors, benzo[a]pyrene(B[a]p) exposure and bacterial challenge, were evaluated on MT gene expression. The level of MT gene transcripts in the liver significantly declined 24 h post B[a]p exposure and the quantity was significantly correlated with the exposure time during a 24 h period. In contrast, MT gene expression in the liver was significantly increased 48 h post bacterial infection and the quantity was significantly correlated with the infection time during this period of 48 h. Our results indicated that MT gene expression in black porgy liver was sensitive to environmental stresses other than just the heavy metal pollution reported, suggesting that the development of a reliable biomarker for heavy metal pollution will be more complex than expected.展开更多
Common carp are among the oldest domesticated fish in the world.As such,there are many food and ornamental carp strains with abundant phenotypic variations due to natural and artificial selection.Hebao red carp(HB,Cyp...Common carp are among the oldest domesticated fish in the world.As such,there are many food and ornamental carp strains with abundant phenotypic variations due to natural and artificial selection.Hebao red carp(HB,Cyprinus carpio wuyuanensis),an indigenous strain in China,is renowned for its unique body morphology and reddish skin.To reveal the genetic basis underlying the distinct skin color of HB,we constructed an improved highfidelity(HiFi) HB genome with good contiguity,completeness,and correctness.Genome structure comparison was conducted between HB and a representative wild strain,Yellow River carp(YR,C.carpio haematopterus),to identify structural variants and genes under positive selection.Signatures of artificial selection during domestication were identified in HB and YR populations,while phenotype mapping was performed in a segregating population generated by HB×YR crosses.Body color in HB was associated with regions with fixed mutations.The simultaneous mutation and superposition of a pair of homologous genes(mitfa) in chromosomes A06 and B06 conferred the reddish color in domesticated HB.Transcriptome analysis of common carp with different alleles of the mitfa mutation confirmed that gene duplication can buffer the deleterious effects of mutation in allotetraploids.This study provides new insights into genotype-phenotype associations in allotetraploid species and lays a foundation for future breeding of common carp.展开更多
Marine sponge Tedania anhelans distributes throughout the intertidal zone of Fujian, southeastern China, and is a potential source of natural bioactive products. The sponge harbors a large number of bacterial groups t...Marine sponge Tedania anhelans distributes throughout the intertidal zone of Fujian, southeastern China, and is a potential source of natural bioactive products. The sponge harbors a large number of bacterial groups that have been identified using various techniques, including fluorescent in situ hybridization （FISH）. Fractionation of dissociated sponge allowed isolation of 25 bacterial species. Based on 16S rRNA gene sequencing, phylogenetic analysis attributed most of these eubacteria to cL-Proteobacteria, y-Proteobacteria, Cytophaga/Flavobacterium/Bacteroidetes （CFB group）, and the family Bacillaceae of Gram-positive bacteria. In sequence similarity, five putatively novel species were identified with less than 98% similarity to other strains in the NCBI database. Tests for antimicrobial activities were performed against Gram-positive bacteria, Gram-negative bacteria, fungi, antitumor indicators Escherichia coli 343/591 （with DNA repair deficiency）, regular E. coli 343/636 （with different DNA repair capacity）, and 10 bacterial isolates exhibited inhibitory bioactivities. Among these strains, three isolates were detected involving function gene NRPS-A domains, which were most closely related to the amino acid sequences of linear gramicidin synthetase and pyoverdine synthetase. These results contribute to our knowledge of the microbes associated with marine sponges and further reveal novel bacterial resources for the screening of bioactive marine natural products.展开更多
Dinitrogen(N_(2))fixed by a group of prokaryotes(diazotrophs)is the dominant process adding bioavailable nitrogen into the ocean.Although it has been intensively studied how N_(2) fixation is controlled by resources(b...Dinitrogen(N_(2))fixed by a group of prokaryotes(diazotrophs)is the dominant process adding bioavailable nitrogen into the ocean.Although it has been intensively studied how N_(2) fixation is controlled by resources(bottom-up factors),it is unclear whether the grazing(top-down control)effectively impacts growth and distribution of different diazotroph groups.In this study,we evaluate this question by conducting log-log regression of diazotroph biomass onto corresponding N_(2) fixation rates in the global ocean.The slope of the regression for Trichodesmium is~0.8,indicating that a small portion of the increase in N_(2) fixation does not accumulate as its biomass.This leads to a conclusion that Trichodesmium is under a substantial top-down control,although bottom-up control still dominates.We also analyze the residuals of the regression in the North Atlantic,concluding that free trichomes of Trichodesmium are subject to stronger top-down control than its colonies.The weak correlation between the biomass and N_(2) fixation of unicellular cyanobacterial diazotrophs indicates that the degree of top-down control on this type of diazotrophs varies greatly.The analyses obtain unrealistic results for diatom-diazotroph assemblages due to complicated nitrogen sources of these symbioses.Our study reveals the variability of top-down control among different diazotroph groups across time and space,suggesting its importance in improving our understandings of ecology of diazotrophs and predictions of N_(2) fixation in biogeochemical models.Measurements of size-specific N_(2) fixation rates and growth rates of different diazotroph groups can be useful to more reliably analyze the top-down control on these key organisms in the global ocean.展开更多
The implications of climate change during the second half of the 20th century have been reported throughout the world. Although marginal seas are sensitive to climate change and anthropogenic impacts, relatively littl...The implications of climate change during the second half of the 20th century have been reported throughout the world. Although marginal seas are sensitive to climate change and anthropogenic impacts, relatively little attention has been given to the South East Asian marginal seas. Thus, to bridge this gap in knowledge, a sediment core was collected from the coastal areas of the Leizhou Peninsula in the South China Sea （SCS） to study the inter-decadal climate change and its consequences using diatom species composition as a proxy record. Diatom absolute abundance varied from 2 300 to 68 000 and averaged 16 000 valves per gram of dry weight （v/gdw）. The fractional dissolution index （F~） was usually below 0.5, which indicates low to moderate preservation of diatom valves at coastal area of the SCS. At the inter-decadal time scale, total diatom abundance was high for the period after 1972, which coincided with 1） increased percentage of planktonic diatom abundance and F~; 2） emergence and dominance of high productivity indicative cosmopolitan species such as Thalassionema nitzschioides and Paralia sulcata （their relative abundance increased from 〈1.5% to 〉7% for the period before and after 1972, respectively）; 3） decreased relative abundance of the small-sized eutrophication indicative species, Cyclotella striata, from 70% to 40%. This study reveals that variations in the abundance of diatoms preserved in the sediment was a function of both production and dissolution/preservation of diatom valves, which in turn was intimately connected to the prevailing environmental/climatic conditions. In conclusion, these data reveal the existence of substantial changes in the coastal SCS in response to the 1970s climate shift that was recorded in different parts of the world.展开更多
Understanding phosphorus dynamics in marine environment is of great importance, and appropriate trac- ers for phosphorus cycling in oceans are invaluable. In this study, two methods were developed for extrac- tion, pu...Understanding phosphorus dynamics in marine environment is of great importance, and appropriate trac- ers for phosphorus cycling in oceans are invaluable. In this study, two methods were developed for extrac- tion, purification, and determination of naturally occurring ^32p and ^33P in rainwater, marine plankton and sediments using both a low-level beta counter （LBC） and an ultra-low-level liquid scintillation spectrome- ter （LSS）. Blanks, chemical yields and counting efficiencies were quantified for both methods. The chemical purification of ^32P and ^33P separated by both procedures was validated by their decay curves. The absorber thickness of aluminum for LBC was assessed as 39.2 mg/cm2. ^32P and ^33P specific activities in some rain samples were determined by both methods and showed good consistent results. The advantage of the LSS over the LBC is apparent in its high counting efficiency and in determining samples with high concentration of stable phosphorus. However, when measuring environmental samples with low concentration of stable phosphorus, such as rainwater, both methods can be used and each has its distinct advantage.展开更多
Dinofl agellates are the major causative agents of harmful algal blooms in the global ocean and they usually form blooms under conditions of very low dissolved inorganic phosphorus(DIP).However,the mechanisms underpin...Dinofl agellates are the major causative agents of harmful algal blooms in the global ocean and they usually form blooms under conditions of very low dissolved inorganic phosphorus(DIP).However,the mechanisms underpinning the dinofl agellate blooms remain unclear.Here,we quantitatively compared protein expression profi les of a marine dinofl agellate,Prorocentrum donghaiense,grown in inorganic P-replete,P-defi cient,and DIP-and dissolved organic phosphorus(DOP)-resupplied conditions by employing a Tandem Mass Tag(TMT)-based quantitative proteomic approach.Proteins involved in intracellular P reallocation,organic P,and non-P lipid utilization were up-regulated under the P-defi cient condition,while inorganic phosphate transporters varied insignifi cantly.In response to the P resupplementation,nitrogen metabolism,ribosome,porphyrin,and chlorophyll metabolism were up-regulated,while lysosome,and starch and sucrose metabolism were down-regulated.Notably,photosynthesis was up-regulated and secondary metabolism was down-regulated only in the DIP-resupplied cells,whereas amino acid metabolism and vitamin B6 metabolism were up-regulated in the DOP-resupplied cells,indicating diff erential response mechanisms of P.donghaiense to DIP or DOP resupplementation.Our results indicated that P.donghaiense initiated multiple strategies in response to an ambient inorganic P-defi ciency,and its efficient DOP assimilation by providing both P and carbon sources might be a key factor driving bloom formations of P.donghaiense in a low DIP environment.展开更多
Recently, there has been growing concerns about environmental issues related to urbanization in China. The intense natural resources utilization and increasing population has brought great pressure, especially in coas...Recently, there has been growing concerns about environmental issues related to urbanization in China. The intense natural resources utilization and increasing population has brought great pressure, especially in coastal areas, consequently affecting the sustainable development of coastal cities. In 2002, Environmental Impact Assessment Act (EIA Act) was enacted in China. Environmental impact assessment targeted at planning, one level of strategic environmental assessment (SEA), thus became a legislative requirement. This paper considers SEA to be one of the important approaches not only to control coastal pollution, but also to conserve coastal ecosystems and finally to achieve sustainable development during urbanization, thus it will be a set an example for other areas of China. The experience of SEA in Xiamen, a coastal city in southeast China, illustrates the potentials of SEA. This paper first briefly introduces the concept and potentials of SEA, then compares two SEA cases and a project EIA case in Xiamen, and finally identifies the key characteristics of SEA.展开更多
文摘Heavy precipitation and extreme drought have caused severe economic losses over South China and Indochina(INCSC)in recent decades.Given the areas with large gross domestic product(GDP)in the INCSC region are distributed along the coastline and greatly affected by global warming,understanding the possible economic impacts induced by future changes in the maximum consecutive 5-day precipitation(RX5day)and the maximum consecutive dry days(CDD)is critical for adaptation planning in this region.Based on the latest data released by phase 6 of the Coupled Model Intercomparison Project(CMIP6),future projections of precipitation extremes with bias correction and their impacts on GDP over the INCSC region under the fossil-fueled development Shared Socioeconomic Pathway(SSP5-8.5)are investigated.Results indicate that RX5day will intensify robustly throughout the INCSC region,while CDD will lengthen in most regions under global warming.The changes in climate consistently dominate the effect on GDP over the INCSC region,rather than the change of GDP.If only considering the effect of climate change on GDP,the changes in precipitation extremes bring a larger impact on the economy in the future to the provinces of Hunan,Jiangxi,Fujian,Guangdong,and Hainan in South China,as well as the Malay Peninsula and southern Cambodia in Indochina.Thus,timely regional adaptation strategies are urgent for these regions.Moreover,from the sub-regional average viewpoint,over two thirds of CMIP6 models agree that maintaining a lower global warming level will reduce the economic impacts from heavy precipitation over the INCSC region.
基金supported by the projects of the National Natural Science Foundation of China(Nos.42076113,42176145)the Fundamental Research Funds for the Central Universities(Nos.20720200106,20720200109).
文摘The inland saltwater lakes harbor exceptional biodiversity.Here,two new species of solitary sessile peritrich ciliates were isolated from Qinghai Lake,the largest inland saltwater lake in China.Their morphology,ciliature,silverline system,and molecular phylogeny were investigated based on live observation,silver staining,and analysis of the small subunit ribosomal DNA(SSU rDNA).Vorticella paraglobosa sp.n.is characterized mainly by its obconical or elongate bell-shaped zooid,C-shaped macronucleus,single ventrally located contractile vacuole,two-rowed infundibular polykinety 3,and 28-38 silverlines between peristome and aboral tro-chal band and 10-15 between aboral trochal band and scopula.Vorticella cotyliformis sp.n.differs from its congeners mainly by its double-layered peristomial lip,cup-shaped zooid,J-shaped macronucleus,single ventrally positioned contractile vacuole,three-rowed infundibular polykinety 3,and 70-85 silverlines between peristome and aboral trochal band and 21-25 between aboral trochal band and scopula.The SSU rDNA sequences of the two new species were obtained,and the subsequent molecular phylogenetic analysis supported their taxonomic classification.
文摘Climate change, resulting from human-caused CO_(2) and other greenhouse gas emissions, is an urgent problem that demands immediate action from everyone. The need to decrease emissions has sparked a renewed emphasis on developing and utilizing offshore Carbon Capture,Utilization,and Storage(CCUS) technologies.While these technologies offer potential solutions to mitigate greenhouse gas emissions,many challenges must be addressed to ensure successful implementation.
基金The National Key R&D Program of China under contract No.2019YFA0606702the National Natural Science Foundation of China under contract Nos 42176222,91858202,41630963,and 41776003+1 种基金the National Science Foundation under contract No.NSF-IIS-2123264the fund suported by the National Aeronautics and Space Administration under contract No.NASA-80NSSC20M0220.
文摘The Agulhas system is the strongest western boundary current system in the Southern Hemisphere and plays an important role in modulating the Indian-to-Atlantic Ocean water exchange by the Agulhas leakage.It is difficult to measure in situ transport of the Agulhas leakage as well as the Agulhas retroflection position due to their intermittent nature.In this study,an innovative kinematic algorithm was designed and applied to the gridded altimeter observational data,to ascertain the longitudinal position of Agulhas retroflection,the stability of Agulhas jet stream,as well as its strength.The results show that the east-west shift of retroflection is related neither to the strength of Agulhas current nor to its stability.Further analysis uncovers the connection between the westward extension of Agulhas jet stream and an anomalous cyclonic circulation at its northern side,which is likely attributed to the local wind stress curl anomaly.To confirm the effect of local wind forcing on the east-west shift of retroflection,numerical sensitivity experiments were conducted.The results show that the local wind stress can induce a similar longitudinal shift of the retroflection as altimetry observations.Further statistical and case study indicates that whether an Agulhas ring can continuously migrate westward to the Atlantic Ocean or re-merge into the main flow depends on the retroflection position.Therefore,the westward retroflection may contribute to a stronger Agulhas leakage than the eastward retroflection.
基金financially supported by the National Natural Science Foundation(40930847,31070442)the Natural Science Foundation of Fujian Province(2012J01150)Public science and technology research funds projects of ocean(201305016,201305041,201305022) and MELRI1003
文摘Harmful algal blooms(HABs) have led to extensive ecological and environmental issues and huge economic losses.Various HAB control techniques have been developed,and biological methods have been paid more attention.Algicidal bacteria is a general designation for bacteria which inhibit algal growth in a direct or indirect manner,and kill or damage the algal cells.A metabolite which is strongly toxic to the dinoflagellate Alexandrium tamarense was produced by strain DH46 of the alga-lysing bacterium Alteromonas sp.The culture conditions were optimized using a single-factor test method.Factors including carbon source,nitrogen source,temperature,initial pH value,rotational speed and salinity were studied.The results showed that the cultivation of the bacteria at 28℃ and 180 r min-1with initial pH 7 and 30 salt contcentration favored both the cell growth and the lysing effect of strain DH46.The optimal medium composition for strain DH46 was determined by means of uniform design experimentation,and the most important components influencing the cell density were tryptone,yeast extract,soluble starch,NaNO3 and MgSO4.When the following culture medium was used(tryptone 14.0g,yeast extract 1.63g,soluble starch 5.0 g,NaNO3 1.6 g,MgSO4 2.3 g in 1L),the largest bacterial dry weight(7.36 g L-1) was obtained,which was an enhancement of 107% compared to the initial medium;and the algal lysis rate was as high as 98.4% which increased nearly 10% after optimization.
基金The 973 Project under contract No. 2009CB421207the National Natural Science Foundation of China under contract Nos 41076094 and 30970450+1 种基金Program for New Century Excellent Talents in University under contract No. NCET-10-0375the Fundamental Research Funds for the Central Universities,SCUT
文摘Dark respiration （non-photorespiratory mitochondrial respiration）, which occurs both in the light and in darkness, is vital for growth and survival of algae and plays a critical role in modulating the carbon balance of them. In the present study, we have investigated dark respiration in the light （RL） and in darkness （RD） in three marine macroalgal species, Hizikia fusiformis （phaeophyta）, Gracilaria lemaneiformis （Rhodophyta） and Ulva lactuca （Chlorophyta）, cultured at 20 ℃ using aeration with two CO2 conditions： current ambient （CO2 concentration about 380 μl/L） and elevated CO2 （approximately 720 μl/L） air. RL was estimated by using the Kok method, whereas RD was determined as the rate of O2 influx at zero light. The results showed that both RL and RD were unchanged for the elevated CO2-grown algae relative to ambient CO2 concentration for all the algal species tested. However, RL was significantly lower than RD across all the algal species and growth CO2 treatments, demonstrating that daytime respiration was partly depressed by the light. The percentage of inhibition of respiration by light was similar between ambient and elevated CO2- grown algae. The ratio of respiration to photosynthesis, which tended to decrease when estimated using RL instead of RD, was not altered for the elevated relative to ambient CO2 concentration. The results suggest that RL, rather than RD, is a more accurate estimate of nonphotorespiratory carbon loss in marine macroalgae during the daytime. It would not be anticipated that elevated atmospheric CO2 would exert a substantial influence on respiratory flux either in the light or in darkness in these particular marine macroalgal species.
基金The State Oceanic Administration Foundation of China under contract No.200805029
文摘Ecological experiments were conducted to examine the effects of seawater containing elevated par- tial pressure of carbon dioxide （p CO2 800 × 10 -6 , 2 000 × 10 -6 , 5 000 × 10 -6 and 10 000 × 10 -6 ） on the survival and reproduction of female Acartia pacifica, Acartia spinicauda, Calanus sinicus and Centropages tenuiremis, which are the dominant copepods in the southern coastal waters of China. The results show that the effects of elevated p CO2 on the survival rates of copepods were species-specific. C. sinicus, which was a macro-copepod, had a higher survival rate （62.01%–71.96%） than the other three species （5.00%–26.67%） during the eight day exposure. The egg production rates of C. sinicus, A. spinicauda and C. tenuiremis were significantly inhibited by the increased p CO2 and the exposure time duration. There were significantly negative impacts on the egg hatching success of A. spinicauda and C. tenuiremis in the p CO2 2 000 × 10 -6 and 10 000 × 10 -6 groups, and, in addition, the exposure time had noticeably impacts on these rates too. This study indicates that the reproductive performances of copepods were sensitive to elevated p CO2 , and that the response of different copepod species to acidified seawater was different. Furthermore, the synergistic effects of seawater acidification and climate change or other pollutant stresses on organisms should be given more attention.
基金The National Key Research and Development Program of China under contract Nos 2016YFA0601302 and 2018FY100202。
文摘The coastal ecosystems are highly sensitive to climate change and are usually influenced by variations in phytoplankton communities and water physiochemical factors.In the present study,the phytoplankton community,chlorophyll a(Chl a)and their relationships with environmental variables and dimethylsulfide(DMS)and dimethylsulfoniopropionate(DMSP)were investigated in spring 2017(March 24 to April 16)in the East China Sea(26.0°-33.0°N,120.0°-128.0°E)and southern Yellow Sea(31.0°-36.0°N,120.0°-125.0°E).The spatial distributions of phytoplankton species composition and cell density were investigated by qualitative and quantitative methods and were compared with historical data to study phytoplankton species succession in the survey area.The results showed that there were 275 phytoplankton species belonging to 90 genera and 6 phyla in the survey area,of which 208 species belonged to 62 genera of Bacillariophyta and 56 species belonged to 20 genera of Pyrrophyta.The dominant phytoplankton species were Skeletonema dohrnii,Chaetoceros vanheurckii and Prorocentrum donghaiense.The phytoplankton cell densities ranged from 0.06×10^(4)cells/L to 418.73×10^(4)cells/L,with an average value of 21.46×10^(4)cells/L.In spring,the average ratio of Bacillariophyta/Pyrrophyta was41.13 for the entire study area.The areas with high phytoplankton cell density were mainly distributed in the northern South Yellow Sea and offshore waters of the East China Sea.According to a canonical correspondence analysis among phytoplankton and environmental parameters,the water Chl a concentrations were notably consistent with phytoplankton cell density(P<0.001),and both showed significant negative correlations with salinity and nitrite(P<0.05)and significant positive correlations with dissolved oxygen and pH(P<0.001).There was a significant positive correlation between diatom(both in cell density and in dominant species)and DMS(P<0.05),which indicated that diatoms play a greater role in DMS production in this investigated area.
基金The National High Technology Research and Development Program of China under contract No. 2008AA09Z408the National Natural Science Foundation of China under contract Nos 40930847, 30940002 and 40876061+1 种基金Fujian Province Natural Science Foundation, China under contract No. 2010J01261the Foundation for Innovative Research Team of Jimei University, China under contract No. 2010A007
文摘The authors have investigated the biochemical events by which marine algal virus infection induces cell cycle arrest. The key G 2 /M-phase regulatory proteins are analyzed by immunobloting in unicel-lular Emiliania huxleyi,suggesting that virus induced cell cycle arrest is related with virus＇s effect on cyclins and cyclin dependent kinases. E. huxleyi virus（EhV） represses Cdc2/cyclinB complex activity by inhibiting the activity of Cdc2 kinase in a phosphorylation-related manner,blocking host cells G 2 /M checkpoint. Dephosphorylated /inactive Cdc25C combined with up-regulation of Wee1 expression at early infect period appears to be important mechanisms by which EhV represses Cdc2/cyclinB complex activity that is required for entry into M phase. This study has allowed us to confirm that algal virus infection leads to selective activation or inhibition of certain cell-cycle factors,which may play a significant role in establishing a more efficient environment for viral gene expression and DNA replication.
基金The National Basic Research Program(973 Program)sponsored by the Ministry of Science and Technology under contract Nos 2014CB953700 and 2014CB953702the National Natural Science Foundation of China under contract Nos 40906040 and 41276063+3 种基金the Fundamental Research Funds for the Central Universities of Chinathe Natural Science Foundation of Fujian Province of China under contract No.2011J01277the Laboratory of Marine Ecosystem and Biogeochemistry of State Oceanic Administration of China under contract No.LMEB201103the Scientific Research Foundation for the Returned Overseas Chinese Scholars,Education of Ministry of China
文摘The performance and integrity of a cassette cross-flow ultrafilter （Pellicon 2, Millipore） are examined with a suite of macromolecules of different molecular masses. The retention coefficient during the cross-flow ultrafiltration experiments increases with increasing molecular mass and reaches 90% with 10 kDa dextran in both milli-Q water and ultrafiltered seawater media. Based on a 90% retention coefficient, the molecular mass cut-off for the ultrafiltration membrane is defined at 10 kDa, which is ten times （1 kDa） that rated by the manufacturer. To further validate the accuracy of the laboratory calibration, the samples from the lower Zhujiang River and the Jiulong River Estuary are ultrafiltered with the cassette ultrafiltration membrane and the colloidal organic carbon abundances in these samples are quantified with the ultrafiltration per- meation model based on time series permeation subsamples. The colloidal organic carbon abundances are 5.8%-21.1% in the Jiulong River Estuary and 5.6%-11.0% in the lower Zhujiang River. These are consistent with the reported values for both estuaries as well as with the colloidal organic carbon abundances in ma- rine environments over the coastal and open oceans with 10 kDa cut-off membranes. Therefore, these field data support the laboratory calibration result and indicate the validity of the experimental and quantification procedure adopted. The discrepancy between the nominal molecular mass cut-off and the actual pore size of the ultrafiltration membrane should be of great concern for research in colloidal and nanoparticle biogeochemistry. Careflfl examination of the membrane integrity should be taken during ultrafiltration ex- oeriments in order to avoid misleading molecular mass cut-off information.
基金Supported by the Science&Technology Basic Resources Investigation Program of China(No.2018FY100202)。
文摘Toxic and harmful algal blooms are usually more frequent in mariculture areas due to the abundant trophic conditions.To investigate the relationship between toxic and harmful microalgae and environmental factors,we set up 12 stations near three mariculture regions(Gouqi Island,Sandu Bay,and Dongshan Bay)in the East China Sea.We collected samples from all four seasons starting from May 2020 to March 2021.We identifi ed 199 species belonging to 70 genera,of which 38 species were toxic and harmful,including 24 species of Dinophyceae,13 species of Bacillariophyceae,and 1 species of Raphidophyceae.The species composition of toxic and harmful microalgae showed a predominance of diatoms in the summer(August),and dinofl agellates in the spring(May),autumn(November),and winter(March).The cell densities of toxic and harmful microalgae were higher in summer(with an average value of 15.34×10^(3) cells/L)than in other seasons,3.53×10^(3) cells/L in spring,1.82×10^(3) cells/L in winter,and 1.0×10^(3) cells/L in autumn.Pseudo-nitzschia pungens,Prorocentrum minimum,Paralia sulcata,and Prorocentrum micans were the dominant species and were available at all 12 stations in the three mariculture areas.We selected 10 toxic and harmful microalgal species with frequency>6 at the survey stations for the redundancy analysis(RDA),and the results show that NO^(-)_(3),water temperature(WT),pH,DO,and NO^(-)_(2) were the main factors on distribution of toxic and harmful microalgae.We concluded that the rich nutrient conditions in the East China Sea mariculture areas increased the potential for the risk of toxic and harmful microalgal bloom outbreaks.
基金This study was supported by the National Natural Science Foundation of China under contract Nos 40232021,40576063 and 40521003the Ministry of Science and Technology of China under contract Nos 2005AA635240 and 2003DF000040.
文摘anoxygenic phototrophic bacteria （AAPB）, which form a unique functional group of heterotrophic bacteria, have the abilit,to utilize light energy. The impact of carbon source and light intensity on the growth and bacteriochlorophyn a （ BChl a） expression of a typical strain of AAPB, Erythrobacter longus strain DSMZ6997 was examined during batch culture and continuous culture. The results showed that the expression of BChl a in DSMZ6997 was regulated by both carbon-source and light conditions, and was stimulated by low availability of carbon but inhibited by light to a certain extent at 300 lx and completely at 1 500 lx. In contrast, cell abundance, and even cell size of this strain, was substantially enhanced under light/dark cycle cultivation conditions over dark conditions, indicating the promotion of growth by light. These results led to the conclusion that utilization of light through BChl a helps AAPB to survive under carbon stress, while light at high intensity is harmful to the synthesis of BChl a in AAPB.
基金sponsored by the National Natural Science Foundation of China (grant No.31100376)the Shanghai Municipal Education Commission (grant No.14YZ001)the MEL Visiting Fellowship Program
文摘Metallothioneins(MTs) are normally considered to be sensitive indicators of heavy metal pollution, but it is less clear whether the MT gene can actively respond to other environmental stresses. In this study, an MT m RNA molecular sequence of 471 bp(full length) was identified in marine cultured black porgy(Acanthopagrus schlegelii), encoding 60 amino acids containing 20 cysteine residues. The MT sequence was highly homologous to that of other fish belonging to the MT superfamily type 1 family. The three dimensional structure of the deduced MT peptide was composed of two metal-binding domains capable of ligating divalent heavy metals. The MT m RNA transcripts were detected in the 11 tested tissues and the highest quantity was present in the liver. Stresses by two factors, benzo[a]pyrene(B[a]p) exposure and bacterial challenge, were evaluated on MT gene expression. The level of MT gene transcripts in the liver significantly declined 24 h post B[a]p exposure and the quantity was significantly correlated with the exposure time during a 24 h period. In contrast, MT gene expression in the liver was significantly increased 48 h post bacterial infection and the quantity was significantly correlated with the infection time during this period of 48 h. Our results indicated that MT gene expression in black porgy liver was sensitive to environmental stresses other than just the heavy metal pollution reported, suggesting that the development of a reliable biomarker for heavy metal pollution will be more complex than expected.
基金supported by the National Key R&D Program of China (2019YFE0119000)National Natural Science Foundation of China (31872561)+1 种基金National Science Fund for Distinguished Young Scholars (32225049)Alliance of International Science Organizations (ANSO-CR-PP-2021-03)。
文摘Common carp are among the oldest domesticated fish in the world.As such,there are many food and ornamental carp strains with abundant phenotypic variations due to natural and artificial selection.Hebao red carp(HB,Cyprinus carpio wuyuanensis),an indigenous strain in China,is renowned for its unique body morphology and reddish skin.To reveal the genetic basis underlying the distinct skin color of HB,we constructed an improved highfidelity(HiFi) HB genome with good contiguity,completeness,and correctness.Genome structure comparison was conducted between HB and a representative wild strain,Yellow River carp(YR,C.carpio haematopterus),to identify structural variants and genes under positive selection.Signatures of artificial selection during domestication were identified in HB and YR populations,while phenotype mapping was performed in a segregating population generated by HB×YR crosses.Body color in HB was associated with regions with fixed mutations.The simultaneous mutation and superposition of a pair of homologous genes(mitfa) in chromosomes A06 and B06 conferred the reddish color in domesticated HB.Transcriptome analysis of common carp with different alleles of the mitfa mutation confirmed that gene duplication can buffer the deleterious effects of mutation in allotetraploids.This study provides new insights into genotype-phenotype associations in allotetraploid species and lays a foundation for future breeding of common carp.
基金Supported by the Natural Science Foundation of Fujian Province,China(No.2011J01245)the Fundamental Research Funds for the Central Universities(No.2010121034)
文摘Marine sponge Tedania anhelans distributes throughout the intertidal zone of Fujian, southeastern China, and is a potential source of natural bioactive products. The sponge harbors a large number of bacterial groups that have been identified using various techniques, including fluorescent in situ hybridization （FISH）. Fractionation of dissociated sponge allowed isolation of 25 bacterial species. Based on 16S rRNA gene sequencing, phylogenetic analysis attributed most of these eubacteria to cL-Proteobacteria, y-Proteobacteria, Cytophaga/Flavobacterium/Bacteroidetes （CFB group）, and the family Bacillaceae of Gram-positive bacteria. In sequence similarity, five putatively novel species were identified with less than 98% similarity to other strains in the NCBI database. Tests for antimicrobial activities were performed against Gram-positive bacteria, Gram-negative bacteria, fungi, antitumor indicators Escherichia coli 343/591 （with DNA repair deficiency）, regular E. coli 343/636 （with different DNA repair capacity）, and 10 bacterial isolates exhibited inhibitory bioactivities. Among these strains, three isolates were detected involving function gene NRPS-A domains, which were most closely related to the amino acid sequences of linear gramicidin synthetase and pyoverdine synthetase. These results contribute to our knowledge of the microbes associated with marine sponges and further reveal novel bacterial resources for the screening of bioactive marine natural products.
基金The National Natural Science Foundation of China under contract Nos 41890802 and 42076153。
文摘Dinitrogen(N_(2))fixed by a group of prokaryotes(diazotrophs)is the dominant process adding bioavailable nitrogen into the ocean.Although it has been intensively studied how N_(2) fixation is controlled by resources(bottom-up factors),it is unclear whether the grazing(top-down control)effectively impacts growth and distribution of different diazotroph groups.In this study,we evaluate this question by conducting log-log regression of diazotroph biomass onto corresponding N_(2) fixation rates in the global ocean.The slope of the regression for Trichodesmium is~0.8,indicating that a small portion of the increase in N_(2) fixation does not accumulate as its biomass.This leads to a conclusion that Trichodesmium is under a substantial top-down control,although bottom-up control still dominates.We also analyze the residuals of the regression in the North Atlantic,concluding that free trichomes of Trichodesmium are subject to stronger top-down control than its colonies.The weak correlation between the biomass and N_(2) fixation of unicellular cyanobacterial diazotrophs indicates that the degree of top-down control on this type of diazotrophs varies greatly.The analyses obtain unrealistic results for diatom-diazotroph assemblages due to complicated nitrogen sources of these symbioses.Our study reveals the variability of top-down control among different diazotroph groups across time and space,suggesting its importance in improving our understandings of ecology of diazotrophs and predictions of N_(2) fixation in biogeochemical models.Measurements of size-specific N_(2) fixation rates and growth rates of different diazotroph groups can be useful to more reliably analyze the top-down control on these key organisms in the global ocean.
基金Supported by the National Natural Science Foundation of China(No.41476116)the National Key Research and Development Program of China(No.2016YFA0601302)
文摘The implications of climate change during the second half of the 20th century have been reported throughout the world. Although marginal seas are sensitive to climate change and anthropogenic impacts, relatively little attention has been given to the South East Asian marginal seas. Thus, to bridge this gap in knowledge, a sediment core was collected from the coastal areas of the Leizhou Peninsula in the South China Sea （SCS） to study the inter-decadal climate change and its consequences using diatom species composition as a proxy record. Diatom absolute abundance varied from 2 300 to 68 000 and averaged 16 000 valves per gram of dry weight （v/gdw）. The fractional dissolution index （F~） was usually below 0.5, which indicates low to moderate preservation of diatom valves at coastal area of the SCS. At the inter-decadal time scale, total diatom abundance was high for the period after 1972, which coincided with 1） increased percentage of planktonic diatom abundance and F~; 2） emergence and dominance of high productivity indicative cosmopolitan species such as Thalassionema nitzschioides and Paralia sulcata （their relative abundance increased from 〈1.5% to 〉7% for the period before and after 1972, respectively）; 3） decreased relative abundance of the small-sized eutrophication indicative species, Cyclotella striata, from 70% to 40%. This study reveals that variations in the abundance of diatoms preserved in the sediment was a function of both production and dissolution/preservation of diatom valves, which in turn was intimately connected to the prevailing environmental/climatic conditions. In conclusion, these data reveal the existence of substantial changes in the coastal SCS in response to the 1970s climate shift that was recorded in different parts of the world.
基金The National Natural Science Foundation of China under contract No.41125020a special scientific research project for public welfare supported by the State Oceanic Administration under contract No.2010050012-3
文摘Understanding phosphorus dynamics in marine environment is of great importance, and appropriate trac- ers for phosphorus cycling in oceans are invaluable. In this study, two methods were developed for extrac- tion, purification, and determination of naturally occurring ^32p and ^33P in rainwater, marine plankton and sediments using both a low-level beta counter （LBC） and an ultra-low-level liquid scintillation spectrome- ter （LSS）. Blanks, chemical yields and counting efficiencies were quantified for both methods. The chemical purification of ^32P and ^33P separated by both procedures was validated by their decay curves. The absorber thickness of aluminum for LBC was assessed as 39.2 mg/cm2. ^32P and ^33P specific activities in some rain samples were determined by both methods and showed good consistent results. The advantage of the LSS over the LBC is apparent in its high counting efficiency and in determining samples with high concentration of stable phosphorus. However, when measuring environmental samples with low concentration of stable phosphorus, such as rainwater, both methods can be used and each has its distinct advantage.
基金Supported by the National Key Research Development Program of China(No.2017YFC1404302)the National Natural Science Foundation of China(Nos.41425021,41706131)+1 种基金the Open Fund of CAS Key Laboratory of Marine Ecology and Environmental Sciences,Institute of Oceanology,Chinese Academy of Sciences(No.KLMEES201806)supported by the“Ten-Thousand Talents Program”for leading talents in science and technological innovation。
文摘Dinofl agellates are the major causative agents of harmful algal blooms in the global ocean and they usually form blooms under conditions of very low dissolved inorganic phosphorus(DIP).However,the mechanisms underpinning the dinofl agellate blooms remain unclear.Here,we quantitatively compared protein expression profi les of a marine dinofl agellate,Prorocentrum donghaiense,grown in inorganic P-replete,P-defi cient,and DIP-and dissolved organic phosphorus(DOP)-resupplied conditions by employing a Tandem Mass Tag(TMT)-based quantitative proteomic approach.Proteins involved in intracellular P reallocation,organic P,and non-P lipid utilization were up-regulated under the P-defi cient condition,while inorganic phosphate transporters varied insignifi cantly.In response to the P resupplementation,nitrogen metabolism,ribosome,porphyrin,and chlorophyll metabolism were up-regulated,while lysosome,and starch and sucrose metabolism were down-regulated.Notably,photosynthesis was up-regulated and secondary metabolism was down-regulated only in the DIP-resupplied cells,whereas amino acid metabolism and vitamin B6 metabolism were up-regulated in the DOP-resupplied cells,indicating diff erential response mechanisms of P.donghaiense to DIP or DOP resupplementation.Our results indicated that P.donghaiense initiated multiple strategies in response to an ambient inorganic P-defi ciency,and its efficient DOP assimilation by providing both P and carbon sources might be a key factor driving bloom formations of P.donghaiense in a low DIP environment.
文摘Recently, there has been growing concerns about environmental issues related to urbanization in China. The intense natural resources utilization and increasing population has brought great pressure, especially in coastal areas, consequently affecting the sustainable development of coastal cities. In 2002, Environmental Impact Assessment Act (EIA Act) was enacted in China. Environmental impact assessment targeted at planning, one level of strategic environmental assessment (SEA), thus became a legislative requirement. This paper considers SEA to be one of the important approaches not only to control coastal pollution, but also to conserve coastal ecosystems and finally to achieve sustainable development during urbanization, thus it will be a set an example for other areas of China. The experience of SEA in Xiamen, a coastal city in southeast China, illustrates the potentials of SEA. This paper first briefly introduces the concept and potentials of SEA, then compares two SEA cases and a project EIA case in Xiamen, and finally identifies the key characteristics of SEA.
