Spatial and temporal dynamics of phytoplankton and bacterioplankton biomass in Sanya Bay, northern South China Sea

The composition of phytoplankton and the dynamics of phytoplankton and bacterioplankton biomass （PB and BB, respectively） of Sanya Bay, South China Sea, were determined. A total of 168 species （67 genera） phytoplankton were identified, including BaciUariophyta （diatom, 128 species）, Pyrrophyta （35 species）, Cyanophyta （3 species）, and Chrysophyta （2 species）. Annual average zbundance of phytoplankton was 1.2 × 107 cells/m^3, with the highest abundance in autumn, and the lowest in summer. Annual average diversity index （H＇） and evenness （J） values were 3.96 and 0.70, respectively. Average chlorophyll-a was 2.5 mg/m^3, and the average PB was 124 mg C/m^3, with the highest value in autumn. Surface PB was higher than the bottom, except for summer. Annual mean bacterioplankton abundance and BB were 6.9 × 10^1l cells/m^3 and 13.8 mg C/m^3, respectively. The highest BB was found in summer, followed by winter, spring, and autumn. Surface BB was higher than bottom all year round. The spatial distribution patterns of PB and BB were very similar with the highest biomass in the estuary, and decreased seaward, primarily due to the terrestrial input from the Sanya River and influx of oceanic water. The main factor influencing PB and BB was dissolved inorganic nitrogen （DIN）. Other factors such as temperature, which is above 22℃ throughout the year, had a negligible impact. The correlation between BB and PB was significant （P 〈 0.01）. The annual average ratio of BB/PB was 0.12 （0.06-0.15）. Phytoplankton primary production was one of the most important factors in controlling the distribution of bacterioplankton.

Environmental Drivers of Temporal and Spatial Fluctuations of Mesozooplankton Community in Daya Bay, Northern South China Sea

The response of zooplankton to the ecological environment in Daya Bay is unclear under the influence of both climate changes and anthropogenic activities on a seasonal to inter-annual scale.Based on monthly surveys and historical data,we found the zooplankton community had changed temporally and spatially.A total of 134 species was recorded during the study,and copepods dominated numerically in terms of diversity and abundance.Both copepods and cladocerans were the main contributors to zooplankton abundance.The community structure of zooplankton was temporally classified into the warm and cold groups,and spatially into the three groups located in the marine cage-culture area(MCCA),the outflow of nuclear power plants(ONPP)and unpolluted waters(UPW).The zooplankton was characterized by low biomass(dry weight),high diversity and abundance in the warm period in contrast to that in the cold period.Compared with the other two groups,the MCCA group of zooplankton showed high abundance,low diversity and biomass.Variations in dominant species were closely related to temperature,salinity and chlorophyll a concentration.Species diversity and dry weight decreased in comparison with 30 years ago,while zooplankton abundance increased.The seasonal variation in zooplankton was affected mainly by temperature that was controlled by monsoon,while the spatial difference in the community structure was probably due to eutrophication in the MCCA and thermal water discharge from ONPP.The zooplankton community is undergoing great changes with the tendency of miniaturization and gelatinization in recent 30 years in Daya Bay.

A Comparison of the Zooplankton Community in the Bay of Bengal and South China Sea During April-May, 2010

This study compares the structure of the zooplankton community in the Bay of Bengal(BoB) and South China Sea(SCS) during the period of spring inter-monsoon, 2010. A total of 215 species of zooplankton were identified, of which 187 species were present in the BoB and 119 in the SCS. Of the taxonomic groups recorded, Copepoda was the most diverse group in all samples followed by pelagic Tunicata, Siphonophorae and Chaetognatha. Flaccisagitta enflata, Cosmocalanus darwinii, Euchaeta larva, Macrura larva and Candacia truncata were predominant both in the BoB and SCS. Moreover, the distribution of some dominant species differed regionally, such as Cypridina dentata, Pleuromamma robusta and Mesosagitta decipiens only in the BoB, and Pleuromamma gracilis, Neocalanus gracilis and Eudoxoides spiralis in the SCS. The average zooplankton abundance was 33.37 ± 7.19 ind. m^(-3) in the BoB and 35.08 ± 2.07 ind. m-3 in the SCS. Copepoda was one of the most abundant groups in the Bo B and SCS. Based on multivariate analysis, it was possible to distinguish the zooplankton in the BoB and SCS communities at the similarity level of approximately 55%, and the dissimilarity was mainly due to C. dentata, P. robusta, M. decipiens, C. darwinii, N. gracilis and P. gracilis. The relationships between zooplankton and temperature, salinity and chlorophyll a were not statistically significant. Zooplankton community structure in the BoB and SCS was observed to be generally similar in terms of species composition and abundance, but the differences observed may be the result of species-specific geographical distribution and local hydrographic conditions.

Distribution, residence time, autotrophic production, and heterotrophic removal of DOP in the Mirs Bay, northern South China Sea

The importance of dissolved organic phosphorus(DOP) as a potential nutrient source for primary producers in marine systems has been recognized for up to eight decades, but currently, the understanding of the biogeochemistry of DOP is in its infancy. In the present study, monthly data between 2000 and 2014 were used to analyze the temporal and spatial distributions of DOP in the Mir Bay, the northern South China Sea. The DOP residence time(TDOP) was also investigated using a simple regression analysis in combination with chlorophyll a(Chl a) measurements while excess DOP(ΔDOP), produced by the biogeochemical processes of autotrophic production and heterotrophic removal, was determined using a two-component mixing mass-balance model in combination with salinity measurements. The results showed that the DOP concentration was(0.017±0.010) mg/L higher in the surface-water compared with the bottom-water and higher in the inner Tolo Harbour and waters adjacent to Shatoujiao compared with the main zone of the bay. Although seasonal changes and annual variability in the DOP were small, the surface DOP concentration was higher in the wet season(April–September)than in the dry season(October–March) due to the impacts of seaward discharges and atmospheric deposition into the bay. Measurement and regression results showed that the DOP release rate from phytoplankton production was about 1.83(gP)/(gChl a) and the TDOP was about 7 d, which implied that the DOP cycle in the bay was rapid. The ΔDOP was calculated from the model to be about 0.000 mg/L in the main zone of the bay and about 0.002 mg/L in the inner Tolo Harbour and waters adjacent to Shaotoujiao, suggesting that the autotrophic production of DOP was almost balanced by the heterotrophic removal in the main zone of the bay and dominated in the inner Tolo Harbour and waters adjacent to Shaotoujiao. In conclusion, the Mirs Bay is very productive and fairly heterotrophic.

An Analysis of the Characteristics of Monsoon Onset over the Bay of Bengal and the South China Sea in 2010

Based on NCEP/NCAR daily reanalysis and the Tropical Rainfall Measuring Mission data, the back- ground atmospheric circulation and the characteristics of meteorological elements during the period of the Bay of Bengal monsoon （BOBM） and the South China Sea （SCS） monsoon （SCSM） in 2010 are studied. The impacts of the BOBM onset on the SCSM onset and the relationship between the two monsoons are also analyzed. The two main results are as follows： （l） The BOBM onset obvi- ously occurs earlier than the SCSM onset in 2010, which is a typical onset process of the Asian monsoon. During the BOBM＇s onset, northward jump, and eastward expansion, convective precipitation and southwest winds occurred over the SCS, which resulted in the onset of the SCSM. （2） The relationship among strong convection, heavy rainfall, and vertical circulation configuration is obtained during the monsoon onsets over the BOB and SCS, and it is concluded that the South Asian High plays an important role in this period.

Application of vertically integrated sampling approach to study of new production via ^(234)Th -^(238)U disequilibria

The spatial and temporal distributions of new production vary largely in different sea areas. To understand the level of new production in the sea area studied better, an estimate of new production must be obtained in large spatial and temporal scales. The ~234Th/ ~238U disequilibrium is an effective method for the study of new production. Two sampling strategies, vertically integrated sampling ap proach based on trapezoidal integration principle and discrete layer sampling approach, were compared in the studies of the xiamen Bay and the northern South China Sea. The scavenging fluxes and removal fluxes of ~234Th and the residence times for dissolved and particulate ~234Th were calculated. The coinci dent results from two Sampling approach suggest that vertically integrated sampling approach is not only effective and reliable, but also significantly reduces the number and volume of samples. It allows us to study new production by ba ^(234)Th - ^(238)U disequilibria in large spatial scale.

南海柘林湾鱼类群落结构季节变动的研究

为阐明南海柘林湾鱼类群落结构的动态变化,基于2011年4月(春季)、8月(夏季)、11月(秋季)和2012年2月(冬季)对南海柘林湾拖网调查的数据,对柘林湾鱼类群落结构季节动态、鱼类营养级指数季节变化进行了初步分析。结果显示,各季节调查共捕获鱼类99种,底层鱼类占49.49%,暖水性鱼类占78.78%,肉食性鱼类占79.79%。各季节质量百分比和数量百分比优势种以拟矛尾■虎鱼(Parachaeturichthys polynema)、龙头鱼(Harpodon nehereus)、皮氏叫姑鱼(Johnius belengeri)等为主。柘林湾鱼类资源密度和资源尾数密度最高季节为夏季,各季节鱼类个体体质量大多小于15 g。春、秋季鱼类组成相对丰富,冬季生物量优势度最高。柘林湾鱼类以中级肉食性和高级肉食性为主,年度平均营养级指数为3.478,属于中级水平,夏季高营养级鱼类平均体质量最高。

南海柘林湾海洋牧场生物碳储量研究

文章以柘林湾海洋牧场海洋生物为研究对象,采用元素分析法,对海洋生物不同组织器官灰化前后碳(C)质量分数进行测定。在此基础上,估算灰化前柘林湾海洋生物C质量分数,探讨海洋牧场生物碳储量。结果表明,1)灰化前柘林湾海洋牧场各生物主要组织器官肌肉、骨骼/壳、内脏C质量分数均值变化分别为37.72%~47.41%、11.23%~34.91%、27.58%~33.95%,其中硬骨鱼纲、甲壳纲(虾)、腹足纲、双壳纲等固碳能力较强,但除头足纲外,总体差别不大。灰化后,主要组织器官肌肉、骨骼/壳、内脏C质量分数均值变化分别为1.83%~8.28%、1.90%~12.54%、0.62%~8.29%,其中腹足纲和双壳纲储碳能力较强;2)2013年柘林湾海洋牧场海洋生物储碳约为6.728×104t。其中人类捕捞从海洋中移除C约0.155×10~4t,占总碳储量的2.31%;沉积在海底的C约0.11×10~4t,占总碳储量的1.7%;封存在海洋内的并不断进入碳循环的C约6.46×10~4t,占总碳储量的95.98%。不同海洋生物碳汇特征不同,海洋牧场可有效提高区域碳汇强度。

柘林湾近代沉积物中甲藻孢囊的垂直分布

于 2001 年 月在柘林湾 个采样点采集了各约 4 3 20 cm的沉积物柱状样,分层研究了甲藻孢囊的垂直分布。在 个沉积物样品中共分析鉴定出甲藻孢囊47 种,而且还观察到了 种该海域特有的种类。 33 3孢囊组成以原多甲藻等异养型孢囊为主,而有毒的亚历山大藻和链状裸甲藻孢囊也均有分布。每个样品中所分析鉴定的孢囊种类数较少,仅有 ～ 种,平均 种。孢囊丰度也较低,在 ～ 5 16 10 59 1 998 cysts/g D Wt之间,平均 280 cysts/g D Wt。香农-威弗种类多样性指数和孢囊种类数都以位于非养殖区湾外海域的 S3站最高,同时在3 个站位的6～8 cm 层次处,随深度的增加均有较大幅度的上升。研究结果表明,柘林湾的富营养化程度较高,而且湾内海域大于湾外海域,养殖区大于非养殖区,近年有加剧的趋势。

1998年夏季南海水团分析

根据 1 998年夏季“南海季风试验 ( SCSMEX)”期间所获的 CTD资料 ,使用系统聚类、Fuzzy模式聚类、Bayes判别分析和 Fuzzy分析等水团分析方法 ,对南海水体的结构和水团配置状况等进行了分析 ,划出了南海存在的 9个主要水团 ,并对各水团的温、盐度特征进行了初析。在调查期间 ,南海本地水 (南海水 )几乎控制了整个调查海区 ,而黑潮水仅出现在台湾岛的西南海域 ;海水强烈混合发生在吕宋海峡附近 ;在中南半岛以东和吕宋岛以西海域 ,表层水明显下沉 ;在南海东南部可能有来自苏禄海的海水 ,其温。

CLIMATIC FEATURES OF SCS SUMMER MONSOON ONSET AND ITS POSSIBLE MECHANISM

The high quality dataset from the SCS (South China Sea) Monsoon Experiment and 40-year NCEP/NCAR reanalysis data are used to investigate the large-scale features and abrupt change in meteorological elements during the onset of the SCS summer monsoon.It is found that the SCS summer monsoon establishment is characterized by the South Asian high migrating swiftly from the eastern side of Philippines to the northern part of Indo-China Peninsula and the enhancement of the Bay of Bengal trough and equatorial westerly over the Indian Ocean associated with the equatorial westerly expanding towards northeastward,and followed by the mid-low latitude interaction and continuous retreat eastward of the western Pacific subtropical high.Further study shows that the meridional temperature difference and the zonal wind vertical shear over the Asian lower latitudes also experience abrupt change during the onset of the SCS summer monsoon. Numerical experiments reveal that the Indian Peninsula acts as a critical role for the enhancement of the Bay of Bengal trough with a cyclonic difference circulation excited to the east side of the peninsula through ground sensible heating in such a way that the SCS summer monsoon occurs prior to the Indian summer monsoon.

Sensitivity of the half-life time of water exchange in coastal waters

A three-dimensional model was established to investigate water exchange in coastal waters, and applied to Qinzhou Bay(QZB) in the South China Sea. Given the strong tidal current in QZB, a half-life time was calculated for water exchange by filtering the tidal signal from the concentrations of a conservative substance. In a control run driven by the tide, without external inputs and an open boundary concentration of zero, it was estimated that the average half-life time in QZB was 54.8 d. Numerical experiments showed that wind accounted for an 11.9% reduction in the half-life time to 48.3 d. When rivers were included in the model, the half-life time decreased by 74.6% to 13.9 d. Sensitivity experiments showed that the half-life time for water exchange was greatly affected by the concentration of the conservative substance which was used at the open boundary. In response to 10,20, 30, and 40% increases in the boundary concentration, the half-life time increased to 91.5, 168.3, 186.2, and 229.1 d,respectively. Results also suggested that for coastal bays with large intertidal areas such as QZB, consideration of the wet and dry processes produced more accurate simulations of the hydrodynamics and the half-life times. Simulations, which did not incorporate wet and dry processes, were more than likely to have overestimated or underestimated the half-life times for water exchange.

柘林湾表层沉积物中甲藻孢囊的分布与浮游植物休眠体萌发研究

于2008年11月采集了广东柘林湾表层沉积物样品,对沉积物中的甲藻孢囊进行分类鉴定,同时对沉积物进行了直接萌发,并对萌发的浮游植物进行了定性定量分析,以了解柘林湾海域甲藻孢囊的分布状况,揭示赤潮发生潜势.研究结果显示,柘林湾海域甲藻孢囊种类多样性较低,仅分析鉴定出甲藻孢囊16种,有毒有害赤潮藻类亚历山大藻和链状裸甲藻的孢囊分布广泛.孢囊组成以异养型甲藻的孢囊占优势,其中,原多甲藻孢囊种类和密度最为丰富,显示了该海域较高的富营养化程度.孢囊密度较低,在16.59~83.37 cysts·g-1(以干重计,下同)之间,平均为39.52 cysts·g-1.空孢囊百分比均较高,平均百分比达到56.3%,说明大部分孢囊已经萌发.萌发的浮游植物种类数较少,共萌发出浮游植物26属33种,硅藻优势种类主要有拟菱形藻(Pseudonitzschia spp.)、角毛藻(Chaetoceros spp.)、中肋骨条藻(Skeletonema costatum)、圆筛藻(Coscinodiscus spp.)等.甲藻种类数较少,其中以woloszynskioid类中的Biecheleriopsis adriatica为优势甲藻.萌发的浮游植物中还出现了大量金色藻(Chrysochromulina spp.)及球形棕囊藻(Phaeocystis globaosa)等其他类别的潜在有毒种类.本研究结果表明,柘林湾海域沉积物中有毒有害赤潮藻类孢囊分布广泛,并萌发出大量的潜在有毒藻类,说明柘林湾海域具有较高的有害赤潮发生风险.

基于贝叶斯分类器的南海黄鳍金枪鱼渔场预报模型

本文利用来自中西太平洋渔业委员会(WCPFC)黄鳍金枪鱼延绳钓2000-2011年的历史渔获数据和美国国家海洋和大气管理局(NOAA)气候预报中心提供的海表温度最优插值数据和法国空间局(CNES)卫星海洋数据中心提供的多卫星融合高度计月合成海面高度资料,基于贝叶斯分类器,根据模型中环境因子的选取以及渔区分类策略的不同预拟了8种构建方案对2011年南海外海黄鳍金枪鱼的渔场进行分类预报,并将预报结果与实际渔场进行对比检验,比较分析不同方案对最终分类结果和精度的影响。检验结果表明,方案1-8总体精度分别为71.4%、75%、70.8%、74.4%、66.7%、68.5%、57.7%和63.7%。方案1-6在65%以上,均能够满足实际渔场预报业务化需求。采用SST和SSH双环境因子的方案均比采用单SST环境因子的方案总体精度稍高,一定程度上提高了预报精度,其中采用去除SST和SSH相关性的第一主分量作为预报因子的方案2达到了75%最高精度。采用CPUE平均值正负标准差作为节点比以33.3%与66.7%作为节点来区分高、中、低CPUE渔区的预报结果要更加准确。因此在模型筛选的基础上,选用模型方案2完成南海金枪鱼渔场渔情预报服务系统的系统实现。