2007 Vol. 26, No. 6

Display Method:
A three-dimensional coupled physical-biological model study in the spring of 1993 in the Bohai Sea of China
WANG Hui, LIU Guimei, SUN Song, HAN Boping, FU Xiang
2007, (6): 1-12.
A three-dimensional(3-D) coupled physical and biological model was used to investigate the physical processes and their influence on the ecosystem dynamics of the Bohai Sea of China.The physical processes include M2 tide,time-varying wind forcing and river discharge.Wind records from 1 to 31 May in 1993 were selected to force the model.The biological model is based on a simple,nitrate and phosphate limited,lower trophic food web system.The simulated results showed that variation of residual currents forced by M2 tide,river discharge and time-varying wind had great impact on the distribution of phytoplankton biomass in the Laizhou Bay.High phytoplankton biomass appeared in the upwelling region.Numerical experiments based on the barotropic model and baroclinic model with no wind and water discharge were also conducted.Differences in the results by the baroclinic model and the barotropic model were significant:more patches appeared in the baroclinic model comparing with the barotropic model.And in the baroclinic model,the subsurface maximum phytoplankton biomass patches formed in the stratified water.
Annual and interannual variations of sea-level anomaly in the Bay of Bengal and the Andaman Sea
QIU Yun, LI Li, YU Weidong, HU Jianyu
2007, (6): 13-29.
Annual and interannual variations of sea-level anomaly(SLA) in the Bay of Bengal and the Andaman Sea are investigated using altimeter-derived SLA data from 1993 to 2003.It is found that the SLA annual variation in the study area can be divided into three phases with distinctive patterns.During the southwest monsoon(May-September),positive SLA presents in the equatorial region and extends northward along the eastern boundary of the bay,and the SLA distribution in the interior bay appears to be high in the east and low in the west with two cyclonic cells developing in the north and south of the western bay respectively,between which an anticyclonic cell exists.During the early northeast monsoon(October-December),the whole bay is dominated by a large cyclonic cell with the pattern of high SLA in the east and low in the west still retained,and the SLA distribution outside the bay is changed in response to the reversal of the Indian Monsoon Current(IMC) in November.During the late northeast monsoon(January-April),a large anticyclonic cell of SLA develops in the bay with negative SLA prevailing in the equatorial region and extending northward along the eastern boundary of bay.Therefore,the SLA distribution in the interior bay reverses to be high in the west and low in the east.It is suggested that the SLA annual variation in the bay is primarily driven by the local wind stress curl,involving Sverdrup balance while the abrupt SLA variation during the peak of northeast monsoon may be partly caused by the semiannual fluctuation of wind in the equatorial region.This fast adjustment in the interior bay is induced by the upwelling coastal Kelvin wave excited by the decay of Wyrtki jet during December through January.Besides the annual variation,in the bay,there are obvious SLA fluctuations with the periods of 2 and 3~7 a,which are driven by the interannual variability of large-scale wind field in the equatorial region.The coastal Kelvin wave also provides an important link for the SLA interannual variation between the equatorial region and the interior bay.It is found that the El Niño-Southern Oscillation(ENSO)-induced influence on the SLA interannual variation in the interior bay is stronger than the Indian Ocean dipole(IOD) with the associated pattern of low sea-level presenting along the periphery of the bay and high sea-level in the northeast of Sri Lanka.
Basic mathematical model for the normal black smoker system and the hydrothermal megaplume formation
LIU Longlong, ZHAI Shikui
2007, (6): 30-40.
A tube model to simulate the normal black smoker system has been built,where the Darcy flow equation,the Ergun equation and the turbulent pipe flow equation are used respectively to describe the dynamic process of different key areas in the hydrothermal circulation system.At the same time,a convection-diffuse Equation for the temperature field is used for describe the exchange of thermal energy and the law of temperature variation.Combining the above facts and using efficient mathematical algorithms and programming with the MatLab programming language,the variation curves of temperature,pressure and mass flow rate are determined,while also the dynamic heat equilibrium and pressure equilibrium within the black smoker system are analyzed.On the basis of the model of the normal black smoker system,a megaplume formation model is further built.For instance,the hydrothermal venting plume on the Juan de Fuca Ridge has been simulated and the simulation results are fairly consistent with Baker's imputed data in 1986.On the basis of the above productive simulation,a series of factors for megaplume formation and the effectiveness of the main parameters of the periodicity of the megaplume formation,temperature and the maximum mass flow rate are systematically discussed.Main conclusions are as follows:The normal black smoker system can evolve into a megaplum eruption.In fact,the passageway of the hydrothermal discharge is blocked by the hydrothermal sediments during the black smoker period,which leads to a hydrothermal fluid accumulation,rise of temperature and increase of buoyancy pressure under the seabed.After a period of 2~3 a,the megaplume hydrothermal eruption will occur when the increasing buoyancy pressure is high enough to crack the blockage(cap).Meanwhile,the temperature of the heat source must exceed 500℃,while the highest temperature of the eruption fluid may be high up to 413℃,which is fairly consistent with the surveying data.If the temperature of the heat source were to be higher than 500℃,then the critical period for the megaplume formation could be obviously curtailed to be less than 1 a,while the critical temperature and the maximum mass flow rate are nearly invariable.As the permeability increases,the maximum mass flow rate increases gradually close to a steady value.
Photoinduced toxicity single and binary mixtures of four polycyclic aromatic hydrocarbons to the marine diatom Skeletonema costatum
MENG Wei, WANG Liping, ZHENG Binghui
2007, (6): 41-50.
Diatom Skeletonema costatum Cleve is one of the main predominant phytoplankton species in the Changjiang Estuary in China.In order to provide some basic information for future assessment of the potential risk on phytoplankton communities in this estuary caused by polycyclic aromatic hydrocarbons(PAHs),this alga was selected as a representative to investigate the photoinduced toxicity of PAHs,in single and mixture.Four PAHs including three-ring phenanthrene and anthracene,four-ring fluoranthene and pyrene were tested in the laboratory.The single toxicity of each PAH on this microalga was compared with and without the simulated solar UV radiation.The results showed that this microalga was sensitive to PAH's photoinduced toxicity.Ratios of the 72 h median effect concentration obtained for fluorescent and UV light tests were about 8.4 for phenanthrene,13.0 for anthracene,6.5 for fluoranthene,and 5.7 for pyrene,indicating that UV light enhanced the PAH toxicity to this alga significantly.Under the fluorescent radiation(lacking UV),the dose-response curves based on chemical concentrations revealed that the order of toxic strength was fluoranthene greater than pyrene greater than anthracene greater than phenanthrene; while under the UV radiation(476 μW/cm2 for UVA,6.5 μW/cm2 for UVB) it became fluoranthene approximately equaling anthracene greater than pyrene greater than phenanthrene,indicating that the UV light also changed its relative toxicity to this alga.The photoinduced toxicity of PAHs to the marine diatom S.costatum might be a synergistic effect of photosensitization reactions(e.g.,generation of single-state oxygen) and photomodification(photooxidation and/or photolysis).The combined effects of six binary mixtures on the marine diatom S.costatum were investigated using the additive-index method.Four binary-mixtures(phenanthrene plus anthracene; phenanthrene plus pyrene; anthracene plus fluoranthene; anthracene plus pyrene) were found to be synergistic joint action mode,while two binary-mixtures(phenanthrene plus fluoranthene; fluoranthene plus pyrene) displayed antagonist,revealing a complex pattern of possible interactions.The combined action mode of PAHs might be related to various factors such as the mixture compounds,mixture ratios and test conditions,etc.
Marine diatom Thalassirosira weissflogii nutrient drawdown and its physiological status variation challenged to zinc and cadmium exposure
LI Chundi, LONG Aimin, YAN Wen, MA Fujun, CHEN Shaoyong
2007, (6): 51-61.
The uptake of zinc and cadmium by a species of marine diatom Thalassirosira weissflogii and the nutrient variation(phosphorus and silicon) in the culture medium were estimated when exposed to zinc and cadmium stress under controlled laboratory conditions.It was found that low cadmium addition could stimulate the culture to grow with a relatively high rate and exert its toxicity at the elevated concentration.The cellular uptake of zinc and cadmium by the diatom varied in the ranges of 1.21~3.75 and 0.060~0.629 fmol per cell respectively in the whole cultivation period.The mean cellular phosphorus and silicon drawdowns were constant with 0.26~0.42 and 0.30~0.46 pmol per cell respectively in those healthy cultures.It is illustrated that the algal cells can adjust some physiological mechanisms to decrease metal accumulation and keep metal homeostasis in the organism.The correlation analysis results further indicate that the cellular cadmium uptake might be closely related with the cellular phosphorus,silicon drawdown and the growth rate of diatom(P<0.05,0.001,0.01); and the cultures grow better in good conditions,the lower amount of phosphorus,silicon materials are consumed by a single cell to keep a high efficiency of utilization.
Macrobenthic community structure in the Changjiang Estuary and its adjacent waters in summer
MENG Wei, LIU Lusan, ZHENG Binghui, LI Xinzheng, LI Zhongyu
2007, (6): 62-71.
On the basis of data collected in the summer of 2006 from 27 sampling stations in the Changjiang Estuary and its adjacent waters,the ecological characteristics of macrobenthos and the relationship between the macrobenthos and the environmental factors were studied using hierarchical cluster and non-metric multidimensional scaling(MDS).The biomass,abundance,Shannon-Wiener's and Margalef's indices of the macrobenthos were presented.The results showed that a total of 253 macrobenthic species were found in the research region,and most of them belong to mollusks and polychaetes.The dominant species were Cossurella dimorpha,Eocylichna cylindrella,Episiphon kiaochowwanense,Nassarius semiplicatus,Ocstergrenia variabilis and Sternaspis scutata.The average abundance of the macrobenthos was(313.15±233.4) ind./m2,and the average biomass was(15.2±11.2)g/m2.The distribution patterns of the abundance and biomass of the macrobenthos were similar.The abundance and biomass in the area close to the estuary were lower than those from the area more distant to the estuary; the central part of the research region had higher abundance and biomass than other parts of the research region.In accordance with the results,four macrobenthic communities with distinct spatial differences were identified.The low abundance and biomass in the area close to the estuary should be caused by the high sedimentation rate.The statistical analysis indicated that the depth is the most important factor affecting the distribution of macrobenthos.
Ontogeny of immune organs during early development stage of P.crocea
XU Xiaojin, WENG Zhaohong, WANG Jun, SU Yongquan
2007, (6): 72-82.
A histological and ultrastructural study was performed on the development of the head kidney,thymus,and spleen in Pseudosciaena crocea aging in range from just hatching to the 60th day after hatching(DAH).Head kidney was first present on the 3rd DAH.Primordial haemopoietic stem cells were first observed in the head kidney which rapidly differentiate into different cellular types.Progenitor spleen was present on the 4th DAH,located close to the gut,which soon became rich in blood capillaries,red blood cells and thrombocytes.The thymus was obvious on the 4th DAH,and was located on either side of the upper corner of the opercular cavity,closely under the membrance of the opercuhr cavity.The thymus was the last lymphoid organ to appear but showed a quick development.This organ seemed to originate from haemopoietic stem cells migrating from the head region of the kidney.The thymus consisted of outer thymocytic and inner epithelioid zones.There was no obvious demarcation between them,but both zones were visible.Small lymphocytes appeared,or lymphoid organs become lymphoid,in the sequence thymus,head kidney and spleen.Only a small number of lymphocytes appeared in the later stages.Non-specific systems may play an important role in the immunocompetence mechanisms of P.crocea during its early development stage.
Phylogenetic analysis of Pectinidae(Bivalvia) based on the ribosomal DNA internal transcribed spacer region
HUANG Xiaoting, BI Ke, HU Jingjie, HU Xiaoli, BAO Zhenmin
2007, (6): 83-90.
The ribosomal DNA internal transcribed spacer(ITS) region is a useful genomic region for understanding evolutionary and genetic relationships.In the current study,the molecular phylogenetic analysis of Pectinidae(Mollusca:Bivalvia) was performed using the nucleotide sequences of the nuclear ITS region in nine species of this family.The sequences were obtained from the scallop species Argopecten irradians,Mizuhopecten yessoensis,Amusium pleuronectes and Mimachlamys nobilis,and compared with the published sequences of Aequipecten opercularis,Chlamys farreri,C.distorta,M.varia,Pecten maximus,and an outgroup species Perna viridis.The molecular phylogenetic tree was constructed by the neighbor-joining and maximum parsimony methods.Phylogenetic analysis based on ITS1,ITS2,or their combination always yielded trees of similar topology.The results support the morphological classifications of bivalve and are nearly consistent with classification of two subfamilies(Chlamydinae and Pectininae) formulated by Waller.However,A.irradians,together with A.opercularis made up of genera Amusium,evidences that they may belong to the subfamily Pectinidae.The data are incompatible with the conclusion of Waller who placed them in Chlamydinae by morphological characteristics.These results provide new insights into the evolutionary relationships among scallop species and contribute to the improvement of existing classification systems.
Gene cloning and sequence analysis of the cold-adapted chaperones DnaK and DnaJ from deep-sea psychrotrophic bacterium Pseudoalteromonas sp.SM9913
ZHAO Dianli, CHEN Xiulan, HE Hailun, SHI Mei, ZHANG Yuzhong
2007, (6): 91-100.
Pseudoalteromonas sp.SM9913 is a phychrotrophic bacterium isolated from the deep-sea sediment.The genes encoding chaperones DnaJ and DnaK of P.sp.SM9913 were cloned by normal PCR and TAIL-PCR(GenBank accession Nos DQ640312,DQ504163).The chaperones DnaJ and DnaK from the strain SM9913 contain such conserved domains as those of many other bacteria,and show some cold-adapted characteristics in their structures when compared with those from psychro-,meso- and themophilic bacteria.It is indicated that chaperones DnaJ and DnaK of P.sp.SM9913 may be adapted to low temperature in deep-sea and function well in assisting folding,assembling and translocation of proteins at low temperature.This research lays a foundation for the further study on the cold-adapted mechanism of chaperones DnaJ and DnaK of cold-adapted microorganisms.
Isolation and identification of a marine killer yeast strain YF07b and cloning of the gene encoding killer toxin from the yeast
WANG Xianghong, CHI Zhenming, LI Jing
2007, (6): 101-108.
It was found that the marine yeast strain YF07b could secrete a large amount of killer toxin against a pathogenic yeast strain WCY which could cause milky disease in Portunus trituberculatus.The marine yeast strain YF07b was identified to be Pichia anomala according to the results of routine yeast identification and 18S rDNA and ITS sequences.The gene encoding killer toxin in the marine yeast strain YF07b was amplified by PCR technology.After sequencing,the results show that an open reading frame,consisting of 1 281 bp,encoded a presumed protein of 427 amino acids.The sequence of the cloned gene was found to have 99% match with that of the gene encoding killer toxin in Pichia anomalas strain K.A signal peptide including 17 amino acids appeared in the N-terminal domain of the killer toxin.Therefore,the mature protein consisted of 410 amino acids,its molecular mass was estimated to be 47.4 ku and its isoelctronic point was 4.5.
Virus-phytoplankton adhesion: a new WSSV transmission route to zooplankton
ZHANG Jiasong, DONG Shuanglin, TIAN Xiangli, DONG Yunwei, LIU Xiangyi, YAN Dongchun
2007, (6): 109-115.
The pathogenicity of white spot syndrome virus(WSSV)to zooplankton species,rotifer Brachionus urceus(Linnaeus),copepod Acartia clausi(Giesbrecht)and mysid shrimp Neomysis awatschensis(Brandt),was estimated by immersion challenge and virus-phytoplankton adhesion route to investigate a potential new transmission route of WSSV to zooplankton.WSSV succeeded in infecting these zooplankton species and nested-PCR revealed positive results for the virus-phytoplankton adhesion route,whereas WSSV cannot infect zooplankton by immersion challenge.These results indicated that virus-phytoplankton adhesion route is a successful new transmission route of WSSV to zooplankton and also implied that phytoplankton could be a carrier in WSSV transmission.
Modeling of the eddy viscosity by breaking waves
ZHANG Shuwen, YUAN Yeli, ZHENG Quan'an
2007, (6): 116-123.
Breaking wave induced nearsurface turbulence has important consequences for many physical and biochemical processes including water column and nutrients mixing,heat and gases exchange across air-sea interface.The energy loss from wave breaking and the bubble plume penetration depth are estimated.As a consequence,the vertical distribution of the turbulent kinetic energy(TKE),the TKE dissipation rate and the eddy viscosity induced by wave breaking are also provided.It is indicated that model results are found to be consistent with the observational evidence that most TKE generated by wave breaking is lost within a depth of a few meters near the sea surface.High turbulence level with intensities of eddy viscosity induced by breaking is nearly four orders larger than υwl(=κu*wz),the value predicted for the wall layer scaling close to the surface,where uw is the friction velocity in water,κ with 0.4 is the von Kármán constant,and z is the water depth,and the strength of the eddy viscosity depends both on wind speed and sea state,and decays rapidly through the depth.This leads to the conclusion that the breaking wave induced vertical mixing is mainly limited to the near surface layer,well above the classical values expected from the similarity theory.Deeper down,however,the effects of wave breaking on the vertical mixing become less important.
In-line response of vertical cylinders in regular and random waves
LI Yok-sheung, SU Wei, ZHAN Jiemin, ZHAN Sheng
2007, (6): 124-138.
The in-line response of a vertical flexibly mounted cylinder in regular and random waves is reported.Both theoretical analyses and experimental measurements have been performed.The theoretical predictions are based on the Morison equation which is solved by the incremental harmonic balance method.Experiments are then performed in a wave flume to determine the accuracy of the Morison equation in predicting the in-line response of the cylinder in regular and random waves.The interaction between waves and vibrating cylinders are investigated.
Numerical modeling on the interaction of internal solitary wave with slope-shelf and modal analysis
LI Qun, XU Zhaoting, CHEN Xu, YU Jia
2007, (6): 139-149.
On the basis of a nonhydrostatic numerical model,the interaction of internal solitary wave with slope-shelf was studied.The breaking and polarity transformation were analyzed.A "kink" structure,due to shoaling topography and higher nonlinear effect,was found to be generated by the leading wave before breaking.Coherent vortex shedding behind the leading wave was presented.The evolution characteristics of the modal structure were analyzed based on the empirical orthogonal function method.The modal structure was complicated due to the effect of the variable topography,especially when breaking occurred.In the performed experiments,the contributions to the total variance from higher mode jumped from no more than 20% to over 40%.
Coextraction of microbial metagenomic DNA and RNA from deep-sea sediment
ZHAO Jing, YANG Xiangsheng, ZENG Runying
2007, (6): 150-157.
A protocol to coextract the microbial metagenomic DNA and RNA from deep-sea sediment was developed for the microbiological study of environmental samples.The obtained pure metagenomic DNA with the size larger than 23 kb and stable RNA could be used directly for PCR and reverse transcription-PCR(RT-PCR)respectively.The direct lysis including the treatments of SDS,proteinase and lysozyme was applied to acquiring the metagenomic DNA and RNA furthest.Prior to the lysis treatment,the glass bead and denaturing solution were added to enhance the lysis efficiency and keep the integrity of RNA respectively.Denaturing gradient gel electrophoresis(DGGE)was applied in accessing the microbial 16S rRNA diversity by PCR and RT-PCR amplification from a single extraction.The pattern obtained by this analysis revealed some differences between them,indicating the efficiency of the protocol in extracting the metagenomic DNA and total RNA from deep-sea sediment.