Top-down control of spring surface phytoplankton blooms by microzooplankton in the Central Yellow Sea,China

Phytoplankton growth and microzooplankton grazing were studied during the 2007 spring bloom in Central Yellow Sea. The surveyed stations were divided to pre-bloom phase (Chl a concentration less than 2 μg L⁻¹), and bloom phase (Chl a concentration greater than 2 μg L⁻¹). Shipboard dilution incubation experiments were carried out at 19 stations to determine the phytoplankton specific growth rates and the specific grazing rates of microzooplankton on phytoplankton. Diatoms dominated in the phytoplankton community in surface waters at most stations. For microzooplankton, Myrionecta rubra and tintinnids were dominant, and heterotrophic dinoflagellate was also important in the community. Phytoplankton-specific growth rates, with an average of 0.60±0.19 d⁻¹, were higher at pre-bloom stations (average 0.62±0.17 d⁻¹), and lower at the bloom stations (average 0.59±0.21 d⁻¹), but the difference of growth rates between bloom and pre-bloom stations was not statistically significant (t test, p=0.77). The phytoplankton mortality rate by microzooplankton grazing averaged 0.41±0.23 d⁻¹ at pre-bloom stations, and 0.58±0.31 d⁻¹ during the blooms. In contrast to the growth rates, the statistic difference of grazing rates between bloom and pre-bloom stations was significant (after removal of outliers, t test, p=0.04), indicating the importance of the top-down control in the phytoplankton bloom processes. Average potential grazing efficiency on primary productivity was 66% at pre-bloom stations and 98% at bloom stations, respectively. Based on our results, the biomass maximum phase (bloom phase) was not the maximum growth rate phase. Both phytoplankton specific growth rate and net growth rate were higher in the pre-bloom phase than during the bloom phase. Microzooplankton grazing mortality rate was positively correlated with phytoplankton growth rate during both phases, but growth and grazing were highly coupled during the booming phase. There was no correlation between phytoplankton growth rate and cell size during the blooms, but they were positive correlated during the pre-bloom phase. Our results indicate that microzooplankton grazing is an important process controlling the growth of phytoplankton in spring bloom period in the Central Yellow Sea, particularly in the “blooming” phase.     

春季黄海微型浮游动物对不同粒径浮游植物的摄食速率研究

于2005年3月对黄海海域的7个站位应用稀释法研究了浮游植物的生长率和微型浮游动物对浮游植物的摄食压力。结果表明：实验期间,微型浮游动物生长速率范围在0．34～0．95d-1,浮游植物摄食速率范围在0．44～0．94d-1。微型浮游动物对浮游植物的现存量和初级生产力的摄食压力分别为47．76％～63．80％和61．50...     

2009年晚春黄海南部浮游植物群落

在2009年6月对黄海南部及中部海域30个站位进行综合调查,对获得的131个浮游植物样品用Utermohl方法进行初步分析,共鉴定浮游植物4门51属73种（不包括未定名种）,其中硅藻32属47种（不包括未定名种）,甲藻17属24种（不包括未定名种）,定鞭藻1门1种,蓝藻1门1种,硅藻在物种丰富度上占有优势。浮游植物的生...     

2009 年晚春黄海南部浮游植物群落

在2009 年6 月对黄海南部及中部海域30 个站位进行综合调查, 对获得的131 个浮游植物样品用Uterm?hl 方法进行初步分析, 共鉴定浮游植物4 门51 属73 种(不包括未定名种), 其中硅藻32 属47种(不包括未定名种), 甲藻17 属24 种(不包括未定名种), 定鞭藻1 门1 种, 蓝藻1 门1 种, 硅藻在物种丰富度上占有优势。浮游植物的生态类型主要以温带近岸种为主, 优势物种为具齿原甲藻(Prorocentrum dentatum)、柔弱伪菱形藻(Pseudo-nitzschia delicatissima)、具槽帕拉藻(Paralia sulcata)等。调查区浮游植物细胞丰度介于0.089 × 10³～1 045.200 × 10³ 个/L, 平均为15.941 × 10³ 个/L, 甲藻的细胞丰度要高于硅藻。细胞丰度高值区位于调查区的南部海域, 以具齿原甲藻为主, 垂向上在10 m 层出现最大值, 随着深度的增加丰度降低。调查区的Shannon-winner 多样性指数和Pielou 均匀度指数的平面分布基本一致, 并且与细胞丰度的分布呈相嵌形式, 即在细胞丰度高的区域多样性指数较低。     

黄、东海春季和秋季微型浮游动物对浮游植物的摄食压力

2000年秋季(10月21日-11月7日)和2001年春季(4月30日-5月15日)用稀释培养法在黄海和东海测定了微型浮游动物对浮游植物的摄食,结果表明:(1)秋季表层浮游植物叶绿素α(Chl α)的内禀生长率为0.40～0.59 d<'-1>,微型浮游动物对Chl α的摄食率为0.21～0.63 d<'-1>,对Ch...     

渤黄海营养盐结构及其潜在限制作用的时空分布

根据2006-2007年4个季节的现场调查资料,分析探讨了渤海和黄海营养盐结构分布变化特征及其对浮游植物生长的潜在的限制状况.结果表明,渤黄海水体 Si/N/P 比值均偏离 Redfield 比值,季节变化明显;春夏冬季 N/P和 Si/P比值由近岸向远岸海域递减,高值区主要分布在黄河口、鸭绿江口及苏北近岸,秋季上层水体N/P和Si/P比值的分布趋势有所不同,高值区主要分布在南黄海的中部海域.受陆源输入的影响,近岸特别是河口区 N/P和 Si/P比值均较高,温跃层的生消变化和生物活动调控着黄海中部海域营养盐结构的变化.渤黄海浮游植物生长主要受P的潜在限制,部分季节受N、Si的潜在限制;营养盐限制状况存在着明显的时空变化及不同营养盐的同时或交替限制的现象.     

春、秋季东、黄海营养盐的分布变化特征及营养结构

利用2000年10～11月和2001年3～4月的调查资料,分析讨论了春、秋季东、黄海营养盐的分布变化特征及营养结构状况。结果表明:该海域表层营养盐高值主要出现在长江冲淡水影响区和江浙近海海域,低值出现于东海陆架区和黄海西北部,黄海中部水域春、秋季因温跃层强弱不同表层营养盐含量差别较大。东、黄海海域春、秋季表层水N/P、Si/N和Si/P值(除秋季黄海北部局部水域N/P值小于10外)均远高于Redfield比值。春季东海海域N/P、Si/N和Si/P值明显高于黄海海域,并高于秋季;秋季黄海海域N/P、Si/N和Si/P值要高于东海海域,变化也大于春季。在强温跃层存在期间和浮游生物旺发季节,表层水域N/P、Si/N和Si/P值原本高的区域往往进一步升高,而温跃层较弱或浮游植物生长繁殖能力较弱的季节,表层水域N/P、Si/N和Si/P值将略有降低。东、黄海水域浮游植物光合作用受N限制的可能性极小,绝大部分水域主要是受P限制,Si的含量普遍较高,它不可能成为限制因子。长江冲淡水区和江浙近海海域过量的N及高N/P值特性且持续升高的趋势可能是近20年来这一地区富营养化程度加剧、赤潮频发的主要原因。     

春季黄海浮游植物生态分区:物种组成

Phytoplanktonic ecological provinces of the Yellow Sea(31.20°–39.23°N, 121.00°–125.16°E) is derived in terms of species composition and hydrological factors(temperature and salinity). 173 samples were collected from 40 stations from April 28 to May 18, 2014, and a total of 185 phytoplanktonic algal species belonging to 81 genera of 7phyla were identified by Uterm?hl method. Phytoplankton abundance in surface waters is concentrated in the west coast of Korean Peninsula and Korea Bay, and communities in those areas are mainly composed of diatoms and cyanobacteria with dominant species of Cylindrotheca closterium, Synechocystis pevalekii, Chroomonas acuta,Paralia sulcata, Thalassiosira pacifica and Karenia mikimotoi, etc. The first ten dominant species of the investigation area are analyzed by multidimensional scaling(MDS) and cluster analysis, then the Yellow Sea is divided into five provinces from Province I(P-I) to Province V(P-V). P-I includes the coastal areas near southern Liaodong Peninsula, with phytoplankton abundance of 35 420×10~3–36 163×10~3 cells/L and an average of 35 791×10~3 cells/L, and 99.84% of biomass is contributed by cyanobacteria. P-II is from Shandong Peninsula to Subei coastal area. Phytoplankton abundance is in a range of 2×10~3–48×10~3 cells/L with an average of 24×10~3cells/L, and 63.69% of biomass is contributed by diatoms. P-III represents the Changjiang(Yangtze River) Diluted Water. Phytoplankton abundance is 10×10~3–37×10~3 cells/L with an average of 24×10~3 cells/L, and 73.14% of biomass is contributed by diatoms. P-IV represents the area affected by the Yellow Sea Warm Current.Phytoplankton abundance ranges from 6×10~3 to 82×10~3 cells/L with an average of 28×10~3 cells/L, and 64.17% of biomass is contributed by diatoms. P-V represents the cold water mass of northern Yellow Sea. Phytoplankton abundance is in a range of 41×10~3–8 912×10~3 cells/L with an average of 1 763×10~3 cells/L, and 89.96% of biomass is contributed by diatoms. Overall, structures of phytoplankton community in spring are quite heterogeneous in different provinces. Canonical correspondence analysis(CCA) result illustrates the relationship between dominant species and environmental factors, and demonstrates that the main environmental factors that affect phytoplankton distribution are nitrate, temperature and salinity.     

黄海中部营养盐的贯跃层输运

黄海中部层化季节上下混合层的温差远高于其他近岸海区,温跃层较强,但通过湍流卷挟仍存在贯跃层物质输运。根据从能量平衡出发的混合层理论模型,计算了黄海中部上、下层的卷挟速度,根据3个航次调查资料,定量估计了层化季节贯跃层的营养盐输运。结果表明:下层黄海冷水团是真光层的营养盐储库,通过湍流卷挟夏季可带来15.9mgC·m-2·d-1的新生产,半个月之内它可以更新上层海洋的营养盐,与大气氮输入作用同量级,远大于大气磷输入;春秋两季贯跃层输入比大气氮输入更为重要,春秋季前者带来的新生产分别为初级生产力的21%和30%,而大气氮输入带来的新生产春季为初级生产的5.7%,秋季为初级生产的9.5%。在整个层化季节营养盐的贯跃层输运带来的新生产在整个初级生产中可能占有很大份额。秋末强风过程带来的强湍流卷挟,可在一周之内更新上层海洋的营养盐,并在风停后刺激上层初级生产的增加。     

Spring phytoplankton bloom in the fronts of the East China Sea

Frontal areas between warm and saline waters of the Kuroshio currents and colder and diluted waters of the East China Sea (ECS) influenced by the Changjiang River were identified from the satellite thermal imagery and hydrological data obtained from the Coastal Ocean Process Experiment (COPEX) cruise during the period between March 1^st and 10^th, 1997. High chlorophyll concentrations appeared in the fronts of the East China Seas with the highest chlorophyll-a concentration in the southwestern area of Jeju Island (~2.9 mg/m³) and the eastern area of the Changjiang River Mouth (~2.8 mg/m³). Vertical structures of temperature, salinity and density were similar, showing the fronts between ECS and Kuroshio waters. The water column was well mixed in the shelf waters and was stratified around the fronts. It is inferred that the optimal condition for light utilization and nutrients induced both from the coastal and deep waters enhances the high phytoplankton productivity in the fronts of the ECS. In addition, the high chlorophyll-a in the fronts seems to have been associated with the water column stability as well.     

东、黄海沉积物-水界面营养盐交换速率的研究

2000年10月和2001年5月随“东方红2号”考察船在东、黄海进行考察,在A2、E2、E4、E5、E65个站位作了培养实验,研究沉积物-水界面在氧化和还原条件下的交换通量。在东海海域,NO3-、PO43-、总磷(TDP)由水向沉积物中扩散,NH4 、SiO32-由沉积物向水中扩散,NO3-、TDP、NH4 在还原条件下的交换通量大于氧化条件下的交换通量,PO43-、SiO32-在氧化还原条件下的交换通量基本一致。在黄海海域,两站位各溶解态营养盐的迁移方向有较大差异。在距离陆地较近的海域,各溶解态营养盐多由水中向沉积物中扩散,且距离陆地越近,交换通量越大。在东、黄海海域,沉积物释放的SiO32-对初级生产力的贡献分别为13%、10%~18%,与河流输送和大气沉降相比,沉积物对黄海、东海SiO32-的贡献分别占90%、86%,说明沉积物是SiO32-的源。而在整个东、黄海海域,对于溶解无机氮(DIN)和PO43-来说,它们的交换通量为负值,即沉积物从水体中吸附溶解无机氮和磷,说明沉积物是DIN和PO43-的汇。     

Distribution of phytoplankton in the East China Sea and the southern Yellow Sea in spring in relation to environmental variables and dimethylsulfide compounds

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, 12...     

黄海苏北浅滩海域春夏季浮游植物时空分布及其控制生态因子

The Subei Shoal is a special coastal area with complex physical oceanographic properties in the Yellow Sea. In the present study, the distribution of phytoplankton and its correlation with environmental factors were studied during spring and summer of 2012 in the Subei Shoal of the Yellow Sea. Phytoplankton species composition and abundance data were accomplished by Uterm?hl method. Diatoms represented the greatest cellular abundance during the study period. In spring, the phytoplankton cell abundance ranged from 1.59×10~3 to 269.78×10~3 cell/L with an average of 41.80×10~3 cell/L, and Skeletonema sp. and Paralia sulcata was the most dominant species. In summer, the average phytoplankton cell abundance was 72.59×10~3 cell/L with the range of 1.78×10~3 to 574.96×10~3 cell/L, and the main dominant species was Pseudo-nitzschia pungens, Skeletonema sp., Dactyliosolen fragilissima and Chaetoceros curvisetus. The results of a redundancy analysis(RDA) showed that turbidity,temperature, salinity, pH, dissolved oxygen(DO), the ratio of dissolved inorganic nitrogen to silicate and SiO_4-Si(DIN/SiO_4-Si) were the most important environmental factors controlling phytoplankton assemblages in spring or summer in the Subei Shoal of the Yellow Sea.     

2014年春季黄、渤海浮游动物群落特征

为了解黄、渤海浮游动物群落特征, 利用2014年春季在黄、渤海采集的浮游动物样品, 对浮游动物的种类组成、丰度、生物量、优势种和生物多样性进行分析, 分析浮游动物群落结构与环境因子间的相关关系, 并划分了浮游动物群落。共记录浮游动物78个种类(南黄海69种、北黄海42种、渤海47种), 浮游幼虫占比最高。研究海域的浮游动物平均丰度为3 183.8±7 829.7 ind./m³, 剔除夜光虫(Noctiluca scintillans)后, 平均丰度为537.3±554.2 ind./m³; 平均生物量为409.1±517.5 mg/m³。夜光虫、中华哲水蚤(Calanus sinicus)和强壮箭虫(Sagitta crassa)是黄、渤海的共同优势种。结合香农-威纳指数和累积优势度曲线分析, 渤海浮游动物的生物多样性最低, 北黄海次之, 南黄海的多样性最高。聚类分析表明, 研究海域浮游动物群落可划分为渤-黄海沿岸群落、黄海中部群落和南黄海-东海近岸混合水群落。相关性分析显示, 研究海域与浮游动物群落结构相关性最高的环境因子组合为温度、盐度和叶绿素a浓度。     

春季水华对南黄海总溶解态无机砷生物地球化学行为的影响

利用氢化物发生-原子荧光光谱法(HG-AFS)对2007年3月30日至4月23日南黄海海域总溶解态无机砷(TDIAs,[TDIAs]=[As5+]+[As3+])的含量进行了测定,其中针对水华中心区域(BM1站)进行了25h的连续观测,以探讨春季水华对有毒类金属元素砷的生物地球化学行为的影响。结果表明,TDIAs的浓度范围为7.9~22.3nmol/L,平均值为(17.8±1.9)nmol/L。TDIAs在南黄海的分布主要表现为由近岸向外海逐渐升高的趋势,最大值出现在南部海域底层海水中。近岸海域表、底层TDIAs的含量相当,而中、南部海域由于存在明显的密度跃层,表、底层TDIAs的浓度具有显著性差异。2007年3月31日至4月1日研究区域西南部受到沙尘天气和降雨的影响,表层海水中TDIAs的含量显著升高。研究区域中、南部海域在观测期间暴发了典型的黄海春季水华,通过大面观测和对重点区域的连续观测可以发现,水华期间TDIAs的分布和磷酸盐类似,与Chl a呈现出较好的负相关关系(r=0.51,P0.05,n=39)。经初步计算,浮游植物水华对10m以上表层水体中TDIAs的清除量约为2.4nmol/L,占表层保有量的15%左右。通过箱式模型计算得出黄海TDIAs的停留时间约为(18.2±8.5)a,远远低于大洋。通过对该海域砷、磷摩尔比值的计算可以发现,南黄海砷、磷摩尔比值约为大洋中的20倍左右,这可能会引起浮游生物对砷酸盐的大量吸收和转化,从而带来潜在的生态危机,需要引起足够的重视。     

黄海冷水团海域浮游植物磷胁迫的季节变动

The Yellow Sea is located between the China Mainland and the Korean Peninsula, representing a typical shallow epicontinental sea. The Yellow Sea Cold Water Mass（YSCWM） is one of the most important physical features in the Yellow Sea. The characteristics of vertical profiles and seasonal variations of biogenic elements in the YSCWM may lead the variations of nutrient availability（e.g., phosphorus） and phosphorus stress of phytoplankton. In this study, the authors surveyed the seasonal variations of phytoplankton phosphorus stress with emphasis on the effect of the YSCWM during the four cruises in April and October 2006, March and August 2007. Using both bulk and single-cell alkaline phosphatase activity（APA） assays, this study evaluated phosphorus status of phytoplankton community, succession of phytoplankton community and ecophysiological responses of phytoplankton to phosphorus in the typical region of the YSCWM. With the occurrence of the YSCWM, especially the variations of concentration of dissolved inorganic phosphorus（DIP）, the results of bulk APA appeared corresponding seasonal variations. Along Transects A and B, the mean APA in August was the highest, and that in March was the lowest. According to the ELF-labeled assay＇s results, seasonal variations of the ELF-labeled percentages within dominant species indicated that diatoms were dominant in March, April and October, while dinoflagellates were dominant in August. During the four cruises, the ELF-labeled percentages of diatoms except Paralia sulcata showed that diatoms were not phosphorus deficient in April 2006 at all, but suffered from severe phosphorus stress in August 2007. In comparison, the ELF-labeled percentages of dinoflagellates were all above 50% during the four time series, which meant dinoflagellates such as Alexandrium and Scrippsiella, sustained perennial phosphorus stress.     

Cross-section restoration and one-dimensional basin modeling of the Central Subbasin in the southern Kunsan Basin,Yellow Sea

The petroleum system of the Kunsan Basin in the Northern South Yellow Sea Basin is not well known, compared to other continental rift basins in the Yellow Sea, despite its substantial hydrocarbon potential. Restoration of two depth-converted seismic profiles across the Central Subbasin in the southern Kunsan Basin shows that extension was interrupted by inversions in the Late Oligocene-Middle Miocene that created anticlinal structures. One-dimensional basin modeling of the IIH-1Xa well suggests that hydrocarbon expulsion in the northeastern margin of the depocenter of the Central Subbasin peaked in the Early Oligocene, predating the inversions. Hydrocarbon generation at the dummy well location in the depocenter of the subbasin began in the Late Paleocene. Most source rocks in the depocenter passed the main expulsion phase except for the shallowest source rocks. Hydrocarbons generated from the depocenter are likely to have migrated southward toward the anticlinal structure and faults away from the traps along the northern and northeastern margins of the depocenter because the basin-fill strata are dipping north. Faulting that continued during the rift phase (∼ Middle Miocene) of the subbasin probably acted as conduits for the escape of hydrocarbons. Thus, the anticlinal structure and associated faults to the south of the dummy well may trap hydrocarbons that have been charged from the shallow source rocks in the depocenter since the Middle Miocene.     

Reanalysis of the Atmospheric Flux of Nutrient Elements to the Southern Yellow Sea and the East China Sea

Based on the recent research results on dry and wet deposition of nutrient elements and sulphate,we estimate the atmospheric flux of nutrient elements and sulphate to the southern Yellow Sea and the East China Sea in each season.The results suggest that the concentrations of nutrient elements and sulphate in aerosol and precipitation show an apparent seasonal cycle with the maximum values in winter and the minimum values in summer.Depositions of nitrate and sulphate are dominated by wet deposition,while the deposition for phosphate is mainly dry deposition.Moreover,compared with the riverine inputs,the atmospheric deposition may be the main source of dissolved inorganic nutrients in the southern Yellow Sea and the East China Sea.     

黄、东海西部营养盐浓度近几十年来的变化

通过对以往调查资料和研究成果的总结,发现黄、东海西部海域在近40～50年中NO3-、SiO32-和PO43-浓度均发生了显著的变化,NO3-浓度快速上升,而SiO32- 和PO43-浓度显著下降.NO3-浓度的上升和SiO32-浓度的下降均与它们在长江等河流中的变化趋势一致;PO43-浓度的下降在河流以及长江口海域并不明显,而更多地体现在较为封闭的渤海、黄海.作者推测,NO3-陆源输入的增加,提高了海洋生产力,加强了浮游植物对PO43的吸收可能是造成PO43-在研究区域平均水平下降的一个原因.基于这个假设,设计了一个简单的数学模型,用以计算为了满足目前PO43-的下降量,外界NO3-输出通量所需的增长速率.结果表明,如果增长的氮通量全部是由长江等河流输出的NO3-提供,这些河流NO3-的平均浓度在近几十年中至少增加了7.8 μmol/L.     

Sediment transport in the Yellow Sea and East China Sea

Eight survey cruises in different seasons have been conducted in the Yellow Sea (YS) and East China Sea (ECS) during the period from 2000 to 2008. Suspended sediment concentration (SSC) and hydrological data were collected during each cruise. Data analysis showed that total suspended sediment mass was approximately 0.18 × 10⁹ tons in the surveyed area during spring and autumn seasons. Highly turbid waters were found in the shallow waters between the Subei coast, the Changjiang estuary and the Zhejiang coast with seasonal variations.