Physical processes and their role on the spatial and temporal variability of the spring phytoplankton bloom in the central Yellow Sea

The spatial and temporal variability of the spring phytoplankton bloom (SPB) in the central Yellow Sea is studied, using SeaWiFS surface chlorophyll remote-sensing data, AVHRR sea surface temperatures (SST), QuikSCAT sea surface wind speed (SSW) from 1998 to 2009 and the cruise survey data in 2007 and 2009. The influences of the hydrological conditions on the SPB are significant. (1) The rising SST and low SSW in spring play an important role in the development of the SPB. The SPB in the central Yellow Sea occurs primarily in April (from April 3 to April 24) and at this period the mean SST is generally greater than 10 °C, and 24 h averaged SSW is less than 5.4 m/s. The 99% of the SPB occurs when the SST is 9–14 °C and SSW is 0–7.9 m/s. (2) Specifically, the development of the SPB is from April 4 to April 7 and from April 4 to April 22 in 2007 and 2009 respectively. The longer duration of the SPB in 2009 than that in 2007 is related to the high SST in 2009, which is approximately 2 °C greater than that in 2007, and the weak SSW in 2009, which is much lower than that in 2007, which further indicate that these two factors are critical to the duration of the SPB. (3) The horizontal distribution of surface chlorophyll a in 2007 is found to be greater and located more northward than that in 2009. Comparing the spatial coverage of the SPB, the path of the Yellow Sea warm current, which is warmer and salty, and the location of maximum SST reveals that the spatial coverage of the SPB locates in the warmer temperature (>9 °C) and higher salinity (>33) waters in March and this warm and salty water was much more evident in 2007 than that in 2009 because a stronger warm current of the Yellow Sea in winter. (4) The vertical depths of the maximum chlorophyll layer (MCL) appear at three levels: surface, 10 m and 30 m in 2007, whereas the MCL occurs only at a sub-surface level in 2009 which is related to vertical stability of the water column, i.e., the water is vertically mixed in 2007 while vertically stratified in 2009.     

东海春季水华期浮游植物生长与微型浮游动物摄食

2005年4～6月在东海有害水华频发区14个站位采样,通过现场稀释法实验对春季东海水域浮游植物比生长率和微型浮游动物比摄食率进行了研究.结果表明东海有害水华频发区浮游植物群落以甲藻为优势.浮游植物比生长率在水华爆发前相对较低,平均为1.18 d~(-1);进入水华期后比生长率明显升高,但在水华站位随现存量增加而降低;非水华区比生长率近岸高、远岸低.微型浮游动物主要以急游虫和桡足类幼体为主,而种类上以砂壳纤毛虫居多.微型浮游动物比摄食率在水华爆发前波动较大,介于0.53～1.73 d~(-1),平均为0.90 d~(-1);在水华区比摄食率较为稳定,浮游植物比生长率的降低导致群落净生长率持续下降;在非水华区,比摄食率整体较高,近岸低而远岸高.微型浮游动物的摄食对浮游植物群落的生长有一定的控制作用,但在水华爆发后这种控制作用将减弱.     

Climate change and the phytoplankton spring bloom: warming and overwintering zooplankton have similar effects on phytoplankton

Indoor mesocosms were used to study the combined effect of warming and of different densities of overwintering mesozooplankton (mainly copepods) on the spring development of phytoplankton in shallow, coastal waters. Similar to previous studies, warming accelerated the spring phytoplankton peak by ca. 1 day °C^?1 whereas zooplankton did not significantly influence timing. Phytoplankton biomass during the experimental period decreased with warming and with higher densities of overwintering zooplankton. Similarly, average cell size and average effective particle size (here: colony size) decreased both with zooplankton density and warming. A decrease in phytoplankton particle size is generally considered at typical footprint of copepod grazing. We conclude that warming induced changes in the magnitude and structure of the phytoplankton spring bloom cannot be understood without considering grazing by overwintering zooplankton.     

基于遥感数据的东海浮游植物生物量时空变化研究

基于地理位置、纬度和生态特征的不同在东海选取了9个面积相同的子区域,采用1997-2015年由SeaWiFS(Sea-Viewing Wide Field-of-View Sensor)和MODIS(Moderate-Resolution Imaging Spectroradiometer)传感器获得的叶绿素a浓度资料,对我国东海浮游植物生物量的时空变化和藻华现象进行了分析。通过高斯曲线模型拟合,得到了藻华爆发的起始时间、峰值时间、结束时间及持续时间。研究表明东海浮游植物生物量在空间上的分布规律为:外海浮游植物生物量小于近岸;长江口和台州列岛海域的浮游植物生物量较大,近黄海海域的两个区域次之,较小的位于南麂列岛海域和台湾海峡,越靠近南部海域浮游植物生物量越低。藻华发生的规律为:以南麂列岛为分界线,由高纬度到低纬度,浮游植物到达藻华发生峰值的时间持续推后,爆发持续时间增长。     

黄海和东海营养盐分布及其对浮游植物的限制

根据1997～1999年黄海和东海4个季节的现场调查资料,分析探讨了黄海、东海的营养盐分布特征及其对浮游植物生长的限制状况．结果表明,在长江口以东及其东北部海域终年存在一个范围很大的营养盐高值区．分析表明,这些营养盐主要来自长江冲淡水的扩展及苏北沿岸流的输送．此外,还获得了1998年长江流域特大洪水期间,迄今被观测到的长江冲淡水中营养盐的最大扩展范围,计算并研究了黄海、东海上层水中Si／N／P比值,结果表明,黄东海上层水中Si／N比值较高,Si不会成为黄东海浮游植物生长的限制因子;但在南黄海南部尤其是西南部、东海近岸及长江口以东海域,N／P比值很高(>30),说明与一般海洋环境的情况不同,黄海、东海有很大一部分海域浮游植物的生长受磷限制,而不是受氮限制．     

Climate change and the timing, magnitude, and composition of the phytoplankton spring bloom

In this article, we show by mesocosm experiments that winter and spring warming will lead to substantial changes in the spring bloom of phytoplankton. The timing of the spring bloom shows only little response to warming as such, while light appears to play a more important role in its initiation. The daily light dose needed for the start of the phytoplankton spring bloom in our experiments agrees well with a recently published critical light intensity found in a field survey of the North Atlantic (around 1.3 mol photons m^?2 day^?1). Experimental temperature elevation had a strong effect on phytoplankton peak biomass (decreasing with temperature), mean cell size (decreasing with temperature) and on the share of microplankton diatoms (decreasing with temperature). All these changes will lead to poorer feeding conditions for copepod zooplankton and, thus, to a less efficient energy transfer from primary to fish production under a warmer climate.     

黄海中部近岸春夏季鱼卵、仔稚鱼群落结构特征

2013年4月下旬至7月上旬,采用浅水I型网垂直拖网的调查方式对黄海中部20m以浅海域(34°30'—35°30'N,119°20'—120°20'E)的鱼卵、仔稚鱼种类组成与数量分布进行了6个航次的综合调查。春夏季共采集鱼卵21种(未定种3种),共计2247粒,隶属于9科15属。仔稚鱼22种(未定种1种),共计286尾,隶属于13科17属。鱼卵优势种为日本鳀Engraulis japonicus、赤鼻棱鳀Thryssa kammalensis、江口小公鱼Stolephorus commersonnii、皮氏叫姑鱼Johnius belengerii和属Callionymus spp.。仔稚鱼优势种为大银鱼Protosalanx chinensis、白姑鱼Argyrosomus argentatus、日本鳀、赤鼻棱鳀和皮氏叫姑鱼。鱼卵丰度和分布与经度呈负相关、与SST呈正相关,但与其他环境因子如纬度、表层盐度(SSS)和水深等无显著相关性。仔稚鱼丰度和分布与上述环境因子均未表现出显著相关性。基于Bray-Curtis指数的聚类分析表明,鱼卵优势种包括集中分布于研究水域34°48'N以南海域(江口小公鱼、皮氏叫姑鱼和青鳞小沙丁Sardinella zunasi)、10m等深线以内(赤鼻棱鳀),以及北部水域(日本鳀和属)3种主要聚集类型;仔稚鱼优势种包括集中分布于34°48'N—35°12'N海域(赤鼻棱鳀和日本鳀)、连云港外海浅水区(白姑鱼、皮氏叫姑鱼和梭鱼Liza haematocheilus,以及南部水域(褐菖鲉Sebastiscus marmoratus和鲬Platycephalus indicus)3种主要聚集类型。研究结果揭示了黄海中部近岸海域鱼卵、仔稚鱼群落的时空分布格局动态,为科学认识环境变动下该海区渔业种群数量动态和资源变化提供了科学依据。     

Earlier onset of the spring phytoplankton bloom in lakes of the temperate zone in a warmer climate

The decoupling of trophic interactions is potentially one of the most severe consequences of climate warming. In lakes and oceans the timing of phytoplankton blooms affects competition within the plankton community as well as food–web interactions with zooplankton and fish. Using Upper Lake Constance as an example, we present a model‐based analysis that predicts that in a future warmer climate, the onset of the spring phytoplankton bloom will occur earlier in the year than it does at present. This is a result of the earlier occurrence of the transition from strong to weak vertical mixing in spring, and of the associated earlier onset of stratification. According to our simulations a shift in the timing of phytoplankton growth resulting from a consistently warmer climate will exceed that resulting from a single unusually warm year. The numerical simulations are complemented by a statistical analysis of long‐term data from Upper Lake Constance which demonstrates that oligotrophication has a negligible effect on the timing of phytoplankton growth in spring and that an early onset of the spring phytoplankton bloom is associated with high air temperatures and low wind speeds.     

Impact of Microzooplankton and Copepods on the Growth of Phytoplankton in the Yellow Sea and East China Sea

Dilution and copepod addition incubations were conducted in the Yellow Sea (June) and the East China Sea (September) in 2003. Microzooplankton grazing rates were in the range of 0.37–0.83 d⁻¹ in most of the experiments (except at Station A3). Correspondingly, 31–50% of the chlorophyll a (Chl a) stock and 81–179% of the Chl a production was grazed by microzooplankton. At the end of 24 h copepod addition incubations, Chl a concentrations were higher in the copepod-added bottles than in the control bottles. The Chl a growth rate in the bottles showed good linear relationship with added copepod abundance. The presence of copepods could enhance the Chl a growth at a rate (Z) of 0.03–0.25 (on average 0.0691) d⁻¹ ind⁻¹ l. This study, therefore parallels many others, which show that microzooplankton are the main grazers of primary production in the sea, whereas copepods appear to have little direct role in controlling phytoplankton.     

Fish assemblage structure in the East China Sea and southern Yellow Sea during autumn and spring

Based on bottom trawl surveys in autumn 2000 and spring 2001, the fish assemblage structure in the southern Yellow Sea and the continental shelf of the East China Sea was analysed. Four groups of fishes were identified for each season by the two-way indicator species analysis (TWIA). Although seasonal migration caused a slight difference in fish assemblages between autumn and spring, two major groups of fishes, corresponding to the Yellow Sea and East China Sea were identified. Inshore and offshore groups were subsequently separated. Changes in water depth may be most important in the separation of the groups in the offshore waters of the East China Sea. Temperature affected the groupings between north and south, particularly in the central part of the Yellow Sea. Here, the cold water mass affected the species composition which was low in diversity and different from the other areas.     

春季和秋季东、黄海陆架区大型网采浮游动物群落划分

根据2000年秋季和2001年春季对黄、东海大面调查中浮游生物大网（孔径500μm）采集的浮游动物样品,运用多元分析方法对陆架区内的浮游动物组成、分布、群落进行了研究。结果表明,春、秋两季陆架区浮游动物均可划分为5个群落：i黄海沿岸群落;ii黄海中部群落;iii黄、东海交汇水混合群落;iv东海近岸混合水群落;v东海外陆架高温高盐群落。各群落的种类组成及地理分布存在一定的季节差异。     

Spatial, seasonal and species variations of harmful algal blooms in the South Yellow Sea and East China Sea

The occurrences of harmful algal blooms (HABs), in terms of frequency and area in the Chinese coastal waters, have been increasing since 1980s and caused considerable economic losses. In the present study, we have analyzed spatial and seasonal characteristics of HAB events in the southern Yellow Sea and East China Sea along Chinese coast from 1933 to 2004. With a total 435 HAB records, the most frequent HAB occurrence area (FHA) is off the Yangtze River mouth and another two FHA areas are located south of the Yangtze River estuary along about isobaths of 30–60 m coastal water in the East China Sea. The time of HAB occurrence shifted during our study period: from autumn (August–October) before 1980s to July–August in 1980s, during May–July in 1990s, and May–June for the period of 2000–2004. Causative species were found to be different: Noctiluca scintillans and Skeletonema costatum were dominant causative species prior to 2000; and Prorocentrum donghaiense Lu was dominant from 2000 to 2004 and also caused large blooms in May. Trichodesmium sp. caused many HABs in autumn (August–October) prior to 1980s with only one HAB between 1980 and 2004. The changes of the dominant HAB species may have affected the timings of HAB occurrence, as well as the increasing HAB-affected areas in recent years.     

东、黄海春秋季小型底栖生物丰度和生物量研究

《北斗号》调查船分别于 2 0 0 0年 10月和 2 0 0 1年 4月在 2 6°N至 36°N,12 0°E至 12 6°30′E东、黄海陆架浅水区调查中进行了小型底栖生物的取样。研究表明 ,两个航次 (秋季、春季 )小型底栖生物的平均丰度分别为 6 5 4 .2 5± 4 4 1.72 ind/10 cm2 和342 .0 0± 2 5 2 .0 0 ind/10 cm- 2 ,平均生物量分别为 80 7.0 6± 5 17.89μg dwt/10 cm2 和 2 85 .2 5± 173.72μg dwt/10 cm2 ;平均生产量分别为 72 6 3.5 8± 4 6 6 4 .18μg dwt/(10 cm2· a)和 2 5 6 7.2 8± 15 6 3.5 0 μg dwt/(10 m2· a)。两个航次小型生物的平面分布类似 ,即高密度和高生物量区分布在水深等深浅 5 0 m左右的站位上 ,特别是在长江口以南的浙江沿海。共鉴定出 14个小型生物类群 ,按丰度自由生活海洋线虫是最优势的类群 ,秋、春季两个航次的优势度分别为 87.2 %和 91.2 %。其他优势类群依次为底栖桡足类、多毛类和动吻类 ;按生物量优势依次为多毛类 38.1%～ 5 4 .0 % ,线虫 2 8.3%～ 38.1%和桡足类 9.0 %～ 9.4 %。垂直分布的研究表明 ,91%的小型生物分布在 0～ 5 cm的表层内 ,线虫和桡足类分布在 0～ 2 cm的比例分别为 6 3%和 86 %。相关分析表明 ,小型底栖生物的数量分布与粘土含量 (% )、粉砂粘土含量 (% )和中值粒     

Biodiversity variability of macrobenthic in the Yellow Sea and East China Sea between 2001 and 2011

In this study, we compared the biodiversity and ecological status of macrobenthos between 2001 and 2011 in terms of species composition, dominant species, abundance, biomass, diversity, and secondary productivity of macrobenthos in the Yellow Sea and East China Sea. The results indicate that the species abundances, biomass, and diversity in spring 2011 were all lower than those in autumn 2000 and spring of 2001. Most of the dominant species have changed from 2001 to 2011, with the exception of the echinoderm Ophiura sarsii vadicola that was dominant in these years. Small-sized animal species have increased possibly due to gradual environment deterioration such as the pollution and the climate warmer.     

2006年夏季南黄海浮游植物叶绿素a分布特征及其环境调控机制

根据2006年夏季南黄海生态调查资料,分析了浮游植物现存量(叶绿素a)的空间分布特征及其主要环境调控机制.结果表明:南黄海浮游植物叶绿素a浓度范围为0.07～12.17 mg/m3,平均值为1.42 mg/m3;浮游植物叶绿素a平面分布呈近岸混合区高于外海层化区的特征,总体上随水体盐度和营养盐梯度的变化而变化,其中浅海陆架锋区对浮游植物有明显的聚集作用,垂直结构中层化区叶绿素次表层最大值现象明显,且最大值的深度和量值具有明显的区域差异;叶绿素a浓度与主要环境因子的相关性分析表明,在较大空间尺度上营养盐是浮游植物的主要调控因子,温度、光照和浮游动物摄食等也在一定空间和程度上对浮游植物的生长产生影响.     

Dynamics in bacterial surface properties of a natural bacterial community in the coastal North Sea during a spring phytoplankton bloom

The hydrophilic and hydrophobic properties of single cells of natural bacterioplankton communities were determined using a recently developed staining method combined with confocal laser scanning microscopy and advanced image analysis. On an average, about 50% of the bacterial cell area was covered by hydrophobic and only 16% by hydrophilic properties, while about 72% was covered by the genome. However, the size of these properties was independent of the bacterial cell size. Bacterial hydrophobicity was positively correlated with ambient NH(4)(+) concentrations and negatively correlated with overall bacterial abundance. The expression of hydrophilicity was more dynamic. Over the spring phytoplankton bloom, the bacterioplankton ratio(phil/phob) repeatedly reached highest values shortly before peaks in bacterioplankton abundance were observed, indicating a direct and fast response of bacterial surface properties, especially hydrophilicity, to changing environmental conditions. Compared to bacterial strains, recently studied with the same method, cells of marine bacterioplankton communities are much smaller and less frequently covered by hydrophobic or hydrophilic properties. While the percentage area covered by the genome is essentially the same, the percentage area covered by hydrophobic or hydrophilic properties is much smaller.     

On the formation of net phytoplankton patches in the southern Black Sea during the spring

Species composition, community structure and spatial distribution of net phytoplankton in the southern Black Sea have been studied. In the fraction over 55 m, diatoms were found to be predominant in cell abundance and followed by dinoflagellates. Net phytoplankters were found to be more abundant in the southwestern sector, especially near the Bosporus and near Sakarya River mouth. MDS (Multi-Dimensional Scaling) analysis has projected four distinct patches along the coast, two of which appear to occupy smaller regions compared to the main western and eastern patches which have lower species numbers and diversity. The diatom species Pseudo-nitzschia seriata and Cerataulina pelagica and the dinoflagellates Noctiluca scintillans and Scrippsiella trochoidea dominate the west, while diatom species Synedra acus and Asterionella formosa together with Microspora sp. and Ankistrodesmus falcatus from chlorophyceae dominate the east.     

香溪河库湾春季水华期间可溶性碳动力学研究

2005年2月23日—4月28日,对三峡水库香溪河库湾内一样点进行每天采样,监测水体中叶绿素a与可溶性碳(DOC)浓度的变化,研究在春季水华暴发期间DOC的动力学特性。监测结果表明,随着时间的推移,叶绿素a有逐渐升高的趋势。其间共暴发了两次水华,其中第一次历时较短,第二次历时较长。DOC的变化趋势与叶绿素a基本吻合。整个暴发过程中的叶绿素a与DOC的回归分析表明,二者具有较好的相关性(R2=0.62),但第一次暴发过程中的相关性很高(R2=0.72),而第二次暴发过程中的相关性较低(R2=0.30)。根据天然水体中DOC来源的主要途径,推测在第一次暴发过程中DOC的来源主要是水体中藻类的光合作用的代谢产物,而第二次暴发过程中DOC的来源主要是水体中藻类死亡腐烂而产生的有机物质。     

香溪河库湾春季叶绿素a 浓度动态及其影响因子分析

2005年3月至4月,对三峡水库香溪河库湾的叶绿素a动态及其与TN、TP等环境因子的关系进行了研究。结果表明,从香溪河库湾下游到上游,叶绿素a存在明显的水平分布。在时间分布上,3月17日暴发一次大规模的水华,4月份水华的暴发有一个明显的平面推移的过程。叶绿素a浓度与TN、TP之间存在着一定的负相关关系,TN与叶绿素a浓度的相关性较显著。香溪河库湾极可能是N限制型水体,而不受P限制。叶绿素a与透明度存在反双曲线关系,与溶解氧呈显著正相关关系。     

Satellite observations of main oceanographic processes to identify ecological associations in the Northern Arabian Sea for fishery resources exploration

Ecological associations are the inter-relationship between the species and their environment. Oceanographic processes like upwelling events and formation of eddies, rings, and fronts have been monitored using National Oceanic and Atmospheric Administration Advanced Very High Resolution (NOAA AVHRR) and Indian Remote Sensing Satellite-P4-Ocean Colour Monitor (IRS-OCM) data. Sea Surface Temperature (SST) and chlorophyll concentration (CC) images were derived from AVHRR and OCM, respectively. Upwelling event was monitored using AVHRR-SST by detecting the differences in surface water temperature. The formation of eddies, rings, cyclonic eddies, and anti-cyclonic eddies and their biological responses were studied using CC. Eddies and rings were found with high phytoplankton production in the form of bloom, which provide grazing ground for fishes. The anti-cyclonic eddies were found with very low CC, indicating the biological deserts in the ocean. The impacts of these processes on fish catch were studied using fishing operations data procured from Fishery Survey of India. In this paper, the occurrence of different oceanographic processes, their persistence, and relevance with catch statistics of fishery resources in the study area are discussed. The study explains the potentials of satellite remote sensing to establish the habitat linkage between oceanographic processes and fishery resources. Guest editor: V. D. Valavanis Essential Fish Habitat Mapping in the Mediterranean