Institutional Repository of South China Sea Institute of Oceanology, CAS
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The typical water masses in the South China Sea and their relations to the Luzon Strait transport
No full text吕宋海峡是南海与外洋相连的唯一深水通道，通过吕宋海峡西北太平洋与南海在各个深度层次上存在广泛的水交换，吕宋海峡水交换对南海温盐分布、物质平衡、环流结构等存在重大影响。但由于观测数据时间和空间上的局限性，而模式同化结果又无法得到充分验证以保证其准确性，吕宋海峡水交换影响下的南海盐度特征及变化一直亟待揭示。本论文主要利用WOD13、ISHII、HYCOM、SODA等实测及同化模式数据研究了南海表层水的季节及年际变化特征，南海北部次表层高盐水分布及其与西北太平洋环流的关系，南海中层低盐水的变化特征及其影响因子，以及南海深层水团及其环流特征。本文取得的主要成果如下：（1）南海北部高盐水核心位于100~200m水深之间，最西可到111°E，具有显著的季节变化周期，高盐水的体积在6月达到最小值，12月达到最大值。进一步的分析表明，其季节变化主要受低纬度西北太平洋大尺度环流的调制，与北赤道流分叉点位置的季节变化（1月到达最北端、6月到达最南端）呈现很好的相关性。受太平洋大尺度风场的影响，北赤道流分叉点上半年（下半年）向南（北）移动，导致黑潮输运增强（减弱），通过吕宋海峡进入南海的盐通量减少（增加），从而使南海次表层高盐水的盐度降低（升高）。吕宋海峡断面的流速和盐通量分布特征显示，西太平洋高盐水主要通过吕宋海峡中部（20°~21.3°N）进入南海北部
Sequence analyses of the ribosomal RNA gene in Soleoidei and its application in phylogenetic inference
No full text核糖体RNA基因（rDNA）具有协同进化和非协同进化两种方式。为了检测鳎亚目（Soleoidei）鱼类rDNA序列是否存在多态性现象，并探究这些序列是否适合作为鳎亚目鱼类系统进化分析的分子标记，本研究通过克隆测序获得了11种鳎科（Soleidae）鱼类共233条rDNA序列以及16种舌鳎科（Cynoglossidae）鱼类共1126条rDNA序列，并应用这些序列构建了鳎亚目鱼类系统进化树。研究结果如下：11种鳎科鱼类中，7个种类的18S-ITS1-5.8S rDNA严格遵循协同进化原则，只有塞内加尔鳎（Solea senegalensis）、缨鳞条鳎（Zebrias crossolepis）、眼斑豹鳎（Pardachirus pavoninus）和卡氏大鼻鳎（Dagetichthys cadenati）四个种的rDNA表现出非协同进化方式；而所有16种舌鳎科鱼类中，都具有两种到五种不同类型的rDNA序列，表明其遵循非协同进化原则
Study on microbial community structure, distribution and diazotrophic diversity in Seagrass meadow, Xincun Bay, South China Sea
No full text海草床中蕴含着丰富的微生物，微生物在生态系统中生源物质循环和能量流动方面发挥重要作用。目前，有关我国南海海草床生态系统中微生物的多样性，特别是固氮群落的分布特征研究还未见系统报道。鉴于此，本论文以南海新村湾海草床生态系统为对象进行相关研究，旨在阐明其中微生物群落结构和分布特征。1) 可培养方法分析南海新村湾海草床细菌群落组成特征通过对南海新村湾海草植株、水体及沉积物样品中可培养细菌分析，共获得496株可培养细菌，其主要分布在芽孢杆菌属(Bacillus)(35.17%)、弧菌属(Vibrio)(14.71%)和希瓦氏菌属(Shewanella)(6.66%)等。沉积物所含可培养细菌数目最多，为207株。海菖蒲(Enhalus acoroides)、泰来藻(Thalassia hemperichii)和海神草(Cymodocea rotundata)周围可培养细菌中差异较大类群为交替单胞菌目(Alteromonadales)、假单孢菌目(Pseudomonadales)和肠杆菌目(Enterobacteriales)。海草床中细菌分布具有季节差异性，夏季和秋季所有样品中细菌数目均高于春季和冬季。3号站位所获得细菌数目最少。另外，对海草床中可培养固氮微生物研究，共获得7株固氮菌，为海草床中固氮微生物深入研究提供了菌株资源
Features of faults and sedimentation in rifting stage in Baiyun sag, Pearl River mouth basin
No full text珠江口盆地白云凹陷地处南海北部深水陆坡区，经历了古近纪两幕裂陷作用，新近纪裂后沉降作用和中中新世以后的构造活化作用，形成了多期继承性和新生性的断层系统和复杂的沉积相分布。前人受资料的限制，多研究裂后期的沉积与构造特征，对裂陷期沉积的维地震资料,其中在白云凹陷西南部和中部有三维地震资料覆盖。二维地震资料多数采集达8 秒的反射信息,部分可达12 秒以上，在新的资料基础之上，部分学者对于裂陷期沉积与构造有了新的认识，提出了低角度铲式断层和拆离断层控凹的观点。但对于拆离断层的发育时间，与铲式断层和高角度断层的关系，对沉积的控制方式等问题，尚缺乏认识。本文在前人的研究基础之上，结合钻井资料和地震剖面，运用测井相分析技术、地震相分析技术和活动速率方法进行白云凹陷裂陷期断裂统计分析以及沉积相划分，重点研究裂陷期白云凹陷低角度断层及断层组合的发育演化以及低角度铲式断层和拆离断层控制下白云凹陷裂陷期沉积相分布特征，并结合断裂和沉积特征进一步探讨低角度断层及断层组合对于沉积的影响和控制作用。主要认识有
Reseach of socio-spatial transition of floating population in Dongguan
No full text当代中国经济社会转型驱动着城市居民社会阶层分化的加剧，而大量迁移流动的外来人口在涌入城市进行空间实践过程中，呈现出典型的人口半城市化特征，成为以“人的城镇化”为核心的新型城镇化建设的重要着力对象。本文选取以“世界工厂”著称的东莞市作为实证案例，采取不同空间单元尺度对宏-微观两种层面上外来人口群体的社会空间演变进行深入解析，试图在对相关外来人口社会空间演变做出有益补充的同时，以期为同类中小城市在推动外来人口市民化和城市空间管治等方面提供启发和借鉴。 本文的研究脉络如下：首先，整理并辨析了外来人口与社会空间的相关概念。其次，通过层层递进式的逐步聚焦，回顾了国内外外来人口社会空间的相关研究，以此作为论文的理论基础。第三章和第四章是本文的重点，分别采取宏观和微观两个尺度层面对东莞市外来人口社会空间演变进行分析。其中，宏观层面上利用2000年和2010年两次人口普查数据，采用因子生态分析和社会区分析法，通过纵向对比得到外来人口社会空间分异演变的特征及规律。微观层面上基于“空间的生产”理论及社会空间辩证法，选取东莞市常平镇还珠沥村为实证案例，采用质性研究的相关分析方法，对外来人口社会空间演变过程及内在机制进行深入研究。最后，总结归纳论文结论，在剖析了研究不足的同时对进一步的研究进行了展望。 本文的主要研究结论包括：（1）通过对2000年和2010年东莞市外来人口社会空间的纵向对比发现，宏观层面上东莞市外来人口社会空间结构在一定程度上保持了原有同质化特征的同时，逐渐演变出较为显著的异质化趋势。同质化特征表现在两个时期均存在较大范围的外来同质人口群体集聚区；而异质化发展趋势主要体现在社会区的空间分布模式则由圈层演变为复杂的圈层—扇形结构。（2）职业差异不仅是直接影响外来人口社会空间分异的重要因子，同时还通过对其他因素产生间接影响来驱动社会空间演化。（3）微观外来人口社会空间的形成与演变是人力资本同质、地缘异构的外来人口个体在其空间生产中过程不断求同存异的过程。以血缘和地缘关系为主的社会生产关系的组织与重构对族群亚社会的形成起到了关键作用。（4）宏观和微观两种尺度层面上的外来人口社会空间演变存在互为照应的映射关系。After the reform and opening up, the social strata polarization of China had been drive by the economic and social transformation. A large number of floating population into the cities and showed remarkable semi-urban population characteristics, during the course of practice space. They are highly focused by the new urbanization strategy that emphasizing on "people oriented urbanization". Starting from different spatial levels and on the macroscopic and microscopic scale, we intensive analysis the Social spatial evolution of the floating population. This paper can enrich the Socio-spatial transformation of domestic study. Furthermore, it is instructive to the Implementation of the floating population urbanization and Social space management in medium-sized and small cities
Analysis of static coulomb stress of earthquakes in the spreading ridge of the South China Sea
No full text应力触发是指地震发生后造成后续断层的力学性质及物理化学性质的改变，抑制或加速断层错动的现象。马尼拉俯冲带及其附近区域是整个南海地震的多发和活跃区域。南海古扩张中脊由于受到后期的火山作用而被改造成为黄岩海山链，黄岩海山链沿着NE向俯冲于马尼拉海沟之下。菲律宾断裂是一条纵贯菲律宾群岛的左旋走滑型断裂，古扩张脊越过海沟的位置恰好是菲律宾断层切过海沟的位置。海山的俯冲及其周缘地区极易引发大震的产生，对海沟的几何形态、构造活动、应力调整必然会造成一定的影响。该处同时也是中国主要的海啸高风险区之一，强震引发的海啸极有可能对我国东南沿海城市造成破坏。因此，对马尼拉俯冲带区域，特别是洋脊俯冲段强震引发的应力场变化、地震活动特点和应力触发等方面的研究具有重要意义。The Coulomb failure function quantitatively describes stress changes in secondary faults near the source fault of an earthquake. Most of earthquakes occur along the Manila trench and its adjacent region. After its extinction the spreding axis was injected by alkalic magmatism delineating the E-W trending Scarborough Seamount chain which along the NE subduction beneath the Manila Trench. The Philippine fault is a left-lateral strike-slip fault extending NNW parallel to Philippine archipelago. Stewart Bank was proposed as a piece of the subducted Scarborough seamount, which has protruded through the forearc in recent time. A reflection profile indicates the Stewart Bank and the West Luzon Trough are separated by a fault zone. Large earthquakes often occur in seamount subduction region. It would affect the geometry of the trench, tectonic activity, stress adjustment. A tsunami induced by a hypothetical earthquake in the Manila Trench is very likely to damage China's southeast coastal cities. There is also one of China's major high-risk areas of tsunami. Therefore, research on the stress field change caused by the earthquake, seismic activity, stress triggering has important significance along the Manila trench and its adjacent region
Molecular cloning and functional characterization of the related genes involved in the Akt-FoxO signaling pathway from the Hong Kong oyster, Crassostrea hongkongensis
No full text香港牡蛎 ( Crassostrea hongkongensis ) 是华南沿海重要的养殖贝类，生活环境复杂多变，长期受到温度、盐度、pH等天然生态环境因子的影响。在长期演化过程中，香港牡蛎形成了很多独特的优良性状，很好地适应了其生存环境，这是基因与环境长期相互作用的结果。解析基因与环境的相互作用，从分子和基因水平上来认识生物适应环境改变的遗传基础，不但是生物学研究中的核心问题之一，而且就香港牡蛎来说，也是对开发保护地区特色的基因资源和良种创制都有深远意义的工作。 通过搜索香港牡蛎血淋巴EST数据库，发现一个Akt1基因的EST序列，然后利用RACE技术克隆获得香港牡蛎Akt1全长cDNA序列 ( ChAkt1 )。香港牡蛎Akt1 cDNA 长度为2223 bp，编码493个氨基酸。该蛋白具有三个保守的结构域：氨基末端的PH结构域，中间的激酶结构域和羧基末端的调节区。多重序列比对分析显示，香港牡蛎Akt1与来自其他物种的同源蛋白高度保守。实时荧光定量PCR分析表明，ChAkt1在香港牡蛎各成体组织和不同胚胎发育时期均有表达，且其mRNA水平在受到病原菌（溶藻弧菌、酿酒酵母）感染和高温刺激后显著上调。亚细胞定位分析显示，ChAkt1蛋白在主要分布于HEK293T细胞的胞质中，少量存在于细胞核中。进一步研究发现，ChAkt1的过表达能够显著激活NF-κB信号通路而抑制p53信号通路。 利用RACE技术，我们从香港牡蛎克隆获得FoxO基因的全长cDNA序列。该序列长度为2367 bp，包括249 bp的5'非编码区，117 bp的3'非编码区以及2001 bp的开放阅读框，它编码666个氨基酸，其中保守的叉头框结构域位于第66位到155位氨基酸，三个高度保守的Akt磷酸化位点分别为T23、S163和S218。组织表达模式分析显示，ChFoxO在消化腺和鳃中分布最多，而在心脏中分布最少。在三种胁迫因子（病原菌、热激和干露）刺激下，ChFoxO的转录水平均明显上升。另外，ChFoxO蛋白主要分布于HEK293T细胞的胞质中，其过表达能够明显激活NF-κB和L8G5报告基因的转录活性。 总而言之，本研究首次克隆Akt-FoxO信号通路中的两个关键基因，并对其功能进行了初步分析。我们的结果不仅丰富了河口软体动物适应多变环境的分子特征、调控与演化机制等相关研究，而且为其优良品种创制等开发利用提供了理论基础和科学根据。Hong Kong oyster, Crassostrea hongkongensis, is an economically important marine aquaculture animal along the coastal waters of the South China Sea. They live a physically harsh and dynamic environment with tremendous exposure, such as daily changes in temperature, salinity and pH. However, the improved oyster varieties with many fine properties have been formed during the long term process of natural evolvement and evolved to acquire powerful defense mechanisms to withstand the environmental stress, which is the result of the interaction of genetic and environmental factors. Understanding the interactions between environments and gene expressions and its molecular basis by which organisms adapt to environmental conditions is one of the fundamental issues of biological research and has far-reaching practical significance for the development and protection of gene resources and the breeding of good strains starting from the Hong Kong oyster. A BLAST analysis of all EST sequences from a C. hongkongensis hemocyte EST library revealed that one EST was homologous to Crassostrea gigas Akt1. By RACE amplification, the full-length cDNA sequence of ChAkt1 was obtained from oysters. The full-length cDNA is 2,223 bp and encodes a putative protein of 493 amino acids that contains an amino-terminal pleckstin homology ( PH ) domain, a central catalytic domain and a carboxy-terminal regulatory domain. Quantitative real-time PCR ( qRT-PCR ) analysis showed that ChAkt1 mRNA is broadly expressed in various tissues and during different stages of the oyster’s embryonic and larval development. Upon exposure to two stressors ( microbial infection and heat shock ), the expression level of ChAkt1 mRNA increases significantly. Furthermore, ChAkt1 is located mainly in the cytoplasm in HEK293T cells, where the over-expression of ChAkt1 regulates the transcriptional activities of NF-κB and p53 reporter genes. ChFoxO, another gene in the Akt-FoxO signaling pathway, was cloned by RACE amplification from C. hongkongensis. The full length cDNA is 2,367 bp containing a 5'-untranslated region ( UTR ) of 249 bp, a 3'-UTR of 117 bp and an open reading frame ( ORF ) of 2,001 bp. The ORF encodes a predicted protein of 666 amino acid residues with a conserved forkhead ( FH ) domain from aa 66 to 155, three highly conserved Akt phosphorylation sites ( T23; S163; S218 ). ChFoxO mRNA could be detected in the above tissues, with poor expression in heart and positive expression in digestive gland and gill. Furthermore, upon exposure to three stressors ( microbial infection, heat shock and aerial exposure ), the expression levels of ChFoxO transcripts had a significant improvement. More importantly, ChFoxO protein is mostly deposited in the cytoplasm in HEK293T cells, while over-expression of the protein enhances the transcriptional activity of NF-κB and L8G5 reporter genes. All in all, we first reported the molecular cloning of two key genes in the Akt-FoxO signaling pathway in the present study from the Hong Kong oyster, C. hongkongensis. Hopefully, these results not only enrich the related study on the molecular characteristics, regulatory and evolutionary mechanisms under which estuarine mollusk adapts to the climate of constant change, but also provide a theoretical and applied foundation for utilizing and creating new germplasm resources
Coherent and incoherent internal tides in the southern South China Sea
No full textCoherent and incoherent internal tides (CITs and ICITs) in the southern South China Sea were investigated from two sets of 18-month mooring current records. The CITs were mainly composed of diurnal Q (1), O (1), P (1) and K (1) and semidiurnal M (2). The observed diurnal internal tides (ITs) were more coherent than the semidiurnal constituents. Coherent diurnal variance accounted for approximately 58% of the diurnal motion, whereas semidiurnal tides contained a much smaller fraction (35%) of coherent motion. The ICITs mainly consisted of motion at non-tidal harmonic frequencies around the tidal frequency, and showed clear intermittency. The modal decomposition of CITs and ICITs showed that CITs were dominated by mode- 1, whereas mode-1 and higher modes in ICITs signals showed comparable amplitudes. CITs and ICITs accounted for approximately 64% and 36% of the total kinetic energy of internal tides, respectively
Experimental investigation of the load exerted by nonstationary internal solitary waves on a submerged slender body over a slope
No full textLaboratory experiments are performed in a large stratified fluid flume to examine the characteristics of the load on a submerged slender body that is exerted by a nonstationary internal solitary wave (ISW) from its interaction with a gentle slope. The nonstationary ISW over the slope and its load on the body are measured by using multi-channel conductivity-probe arrays and a specially designed force measurement device, respectively, and the body's vertical and horizontal positions on the load are determined by analyzing the effects of the incident ISW's amplitude. The experimental"results show that the load on the slender body increases as the incident ISW's amplitude increases; additionally, the effect of oscillations is enhanced because of the ISW's distortion, breaking and fission. The oscillating action from fission waves becomes dominant as the amplitude reaches a certain value. Additionally, the load is correlated with body's vertical position relative to the pycnocline. The magnitudes of the vertical and horizontal forces reach a maximum and minimum in the pycnocline, respectively, and the horizontal force in this direction is the opposite above and below the pycnocline. Compared to a case without a slope, the load on the slender body increases because of the nonstationary ISW, and its effect on the maximum force is transferred to the pycnocline. When the body's horizontal position is located close to the top of the slope, the direction of the horizontal and vertical forces remains consistent, but its acting time becomes longer. In addition, high-frequency actions on the slender body are impacted by nonstationary ISWs near the slope's top. (C) 2016 Elsevier Ltd. All rights reserved
Abnormally high phytoplankton biomass near the lagoon mouth in the Huangyan Atoll, South China Sea
No full textNutrient concentration and phytoplankton biomass were investigated in Huangyan Atoll in May 2015. The concentrations of nutrients were very low, and dissolved inorganic nitrogen was composed mainly of ammonia. Nitrogen likely was the primary limiting factor for phytoplankton growth. The spatial variation of phytoplankton biomass was significant among the lagoon, reef flats, and outer reef slopes. Extremely high chlorophyll a concentration and micro-phytoplankton abundance were found in the region near the lagoon mouth. This high phytoplankton biomass might be due to nutrient input from fishing vessels and phytoplankton aggregation driven by the southwestern wind. Our results indicate that phytoplankton biomass could be a reliable indicator of habitat differences in this coral reef ecosystem, and micro-phytoplankton seems to be more sensitive to nutrient input than pico-phytoplankton. (C) 2016 Elsevier Ltd. All rights reserved