东海赤潮异弯藻Heterosigma akashiwo的形态特征及其分子序列分析

将采集自东海南麂列岛海域水样进行分离、纯化,从中得到1株针胞藻,将其初步鉴定为赤潮异弯藻Heterosigma akashiwo(以下称东海藻株),并使用光学和荧光显微镜对其形态特征进行了详尽描述,及通过rDNA ITS序列测定、系统发育进化树构建和Jukes-Cantor距离矩阵分析,研究了其分子进化关系.结果表明:...     

一株桑沟湾赤潮藻的分子鉴定

2011年5月山东荣成桑沟湾近海海域暴发赤潮,其规模在桑沟湾历史上罕见,较严重地影响了该海域水产动物的人工养殖。本文作者分离得到了赤潮暴发过程中海水里的一株优势种,并对其核糖体18S RNA基因(18S rDNA)和转录单元内间隔区(ITS)进行了序列扩增和分析。依据这两种序列构建的系统进化树都显示这株藻与卡罗藻Karlodinium veneficum(=K.micrum)完全聚在一起,因此推断出其应为K.veneficum,是一种常见有害赤潮藻。本文是卡罗藻在桑沟湾海域暴发的首次报道。     

剧毒卡尔藻与东海原甲藻间的化感作用研究

为研究剧毒卡尔藻(Karlodinium veneficum)与东海原甲藻(Prorocentrum donghaiense)之间的化感作用,在f/2营养盐条件下,分别采用了混合培养及滤液培养的方法。结果表明:剧毒卡尔藻指数生长后期的无藻细胞滤液明显抑制了东海原甲藻的生长,而东海原甲藻滤液对剧毒卡尔藻的生长几乎无影响,化感作用作为重要的影响因素使剧毒卡尔藻获得竞争优势。将剧毒卡尔藻指数生长末期的无藻细胞滤液置于固相萃取(SPE) C18小柱,经吸附、不同比例的甲醇溶液洗脱,考察不同洗脱部分对东海原甲藻生长的影响,发现80%的甲醇洗脱部分明显抑制了东海原甲藻的生长。本研究为了解剧毒卡尔藻的竞争机制提供了重要的科学依据,今后将重点分析剧毒卡尔藻释放的有效抑制东海原甲藻生长的化感物质。     

Effects of static stability and the C/N ratio on aggregation processes of oceanic particles

The cumulative numbers of particles obtained from seven waters in the depth range of 0–100 m in coastal seas and in the North Pacific Ocean followed a hyperbolic distribution with two segments on log-log plots (132 sets of data). An alteration of the segment-slope in the fine size classes (1.59–10.08 μm in the coastal region, 1.59–6.35 μm in the open sea) was assumed to show a loss or a supply of fine particles due to aggregation or disaggregation. We studied relationships between segment slopes, static stabilities of water above the pycnocline which concern the dynamics of particles, and C/N ratios as an indicator of freshness of particles. A negative correlation between the segment-slope of particle size distribution and static stability was obtained, though the slope P of the regression line varied from 0.059 to 0.316. The average C/N ratio in the waters were in the range of 7.5 to 16.3. The slope P negatively correlated to the C/N ratio (r=−0.97). The present results suggested that aggregations of fine-sized particles in the sea are activated in the water with fresh organic matter and with high static stability.     

东海三叶原甲藻的形态特征及其ITS序列分析

报道了首次分离于东海海域的三叶原甲藻(Prorocentrum triestinum Schiller)藻株号(LAMB100721),通过利用光学显微镜、荧光显微镜、扫描电镜及分子生物学方法,对其形态特征、显微结构和分子系统进化进行了详尽描述和鉴定。细胞长卵形或披针形,后端细长且尖,前端圆,最宽部位于细胞中央。顶刺长而显,三角状。壳面光滑,无刺或突起物。刺丝胞孔稀疏而不规则地分布于壳面边缘。叶绿体无具体形状,分布于整个细胞中,细胞核球形,位于中下部。老化的细胞可见细胞边缘的间接带,且间接带表面光滑。细胞长为19~25 μm,平均值为(22.6±0.9)μm;宽为11~16 μm,平均值为(13.2±1.1) μm。所测目标藻株的rDNA ITS序列长度为569 bp,其中GC含量为47.6%。三叶原甲藻系赤潮种,为东海原甲藻春季大规模赤潮的伴随种。加强有害赤潮的预防和监测工作是减少危害的有效途径,而对赤潮原因种的准确识别和鉴定则是基础和关键。     

春、秋季南黄海浮游纤毛虫丰度及生物量的分布差异

Seasonal variation of marine plankton spatial distribution is important in understanding the biological processes in the ocean.In this study,we studied spatial distribution of planktonic ciliate abundance and biomass in the central deep area(station depth greater than 60 m) and the coastal shallow area(station depth less than 60 m) of the southern Yellow Sea(32°–36.5°N,121°–125°E) in spring(April) and autumn(October–November) of 2006.Our results showed that both ciliate abundance and biomass in the surface waters were higher in spring((1 490±2 336)ind./L;(4.11±7.81) μg/L) than in autumn((972±823) ind./L;(1.11±1.18) μg/L,calculated by carbon).Ciliate abundance and biomass in the surface waters of the coastal shallow area were similar in spring and autumn.However,in the central deep area,those values were much higher in spring((1 878±2 893) ind./L;(5.99±10.10)μg/L) than in autumn((738±373) ind./L;(0.74±0.76) μg/L).High values of ciliate abundance and biomass occurred in the central deep area in spring and in the coastal shallow area in autumn.Mixotrophic ciliate Laboea strobila was abundant in the central deep area in spring,when a phytoplankton bloom occurred.However,in autumn,L.strobila was abundant in the coastal shallow area.Boreal tintinnid Ptychocyli obtusa was found in spring.Both L.strobila and P.obtusa were concentrated in the surface waters when their abundance was more than 1 000 ind./L.Peaks of these species were in the subsurface waters when their abundance was less than 400 ind./L.This study showed that both high abundance and biomass of ciliates occurred in different areas in southern Yellow Sea seasonally.     

Molecular diversity of phytoplankton in the East China Sea around Jeju Island (Korea), unraveled by pyrosequencing

The East China Sea (ECS) around Jeju Island lies in a transitional region between the temperate and subtropical zones and is influenced by the Kuroshio Current. Hence, this area has been considered an important monitoring site for oceanic ecosystem changes. Herein, we assessed the community structure and diversity of the phytoplankton in the ECS around Jeju Island using small subunit ribosomal RNA pyrosequencing. We analyzed eight samples collected from the surface and at 30 m- and/or 50-m depths from two neritic and oceanic stations each from 24–30 April 2011. Comparisons of 15,498 pyrosequences identified 172 phylotypes of phytoplankton, excluding cyanobacteria, from the four surface stations. These pyrosequences were represented by dinoflagellates (29 %), stramenopiles (31 %), and chlorophytes (>39 %), with minor contributions from cryptophytes, haptophytes, and Telonemia. Phylotypes retrieved at 30- and 50-m depths were very similar to the surface samples. However, phylotype diversity and community structure varied considerably with the stations. Dominant phylotypes included Karlodinium veneficum, Ostreococcus tauri, Skeletonema marinoi, and Thalassiosira curviseriata, and many of the detected phylotypes include new records for the present study area. This study provides a valuable phylotype reference for future phytoplankton community structure and diversity studies with regard to marine environmental changes.     

Evidence of microphytobenthic roles on coastal shallow water of the Seto Inland Sea,Japan

This study describes the temporal variation of microphytobenthic biomass and its controlling factors, as well as the impact of microphytobenthic activities on coastal shallow sediment in the eastern Seto Inland Sea, Japan. The chlorophyll a (Chl a), phaeopigments and sedimentary biophilic element (C, N, P and Si) contents in surface sediments, as well as nutrient concentrations at the sediment-water interface (overlying water and pore water) were observed monthly during November 2003 to May 2005 at one site in Shido Bay (water depth ca. 7 m) and at one site in Harima-Nada (35 m). No correlation was observed between the sedimentary biophilic elements and other parameters. The maximum chlorophyll a content of 48.2 μg g^–1 was found in surface sediments under the photon flux reaching the seafloor of 537 μmol photon m^–2 s^–1 during the winter period when water transparency was the highest at station S (Shido Bay). Our results suggest that higher chlorophyll a content in surface sediment was due to the fresh microphytobenthic biomass (mainly benthic diatom). We also found a significant negative correlation between Chl a and inorganic nutrients in pore water during the low temperature period, especially silicic acid. This result suggests that the silicic acid was assimilated largely during the increase of microphytobenthic biomass in surface sediment. This study suggests that the microphytobenthic roles may have a great effect on nutrient budgets during the large supply of irradiance (winter periods) for their photosynthetic growth in shallow coastal waters.     

东海2012年夏季海-气界面碳交换及其区域碳汇强度变化趋势初探

基于2012年7月对东海的调查,剖析了其水体中各形态碳(pCO2、DIC、DOC、POC)的区域分布特征,估算了海-气界面CO2的交换通量(FCO2),探讨了影响其交换的主要因素,在此基础上,结合历史资料初步分析了近十几年来该海域海-气界面CO2交换通量的变化趋势。结果表明,2012年7月长江口邻近海域相对南部陆架区具有较低的DIC浓度,而DOC与POC的浓度相对较高。调查区域表层水pCO2变化范围为96.28~577.7μatm(1atm为101 325Pa),平均值为297.6μatm,低值区出现在长江冲淡水区(30°~33°N,123°~125°E),高值区主要分布在东海陆架的南部区域。表层水pCO2主要受控于长江冲淡水的输入和混合(盐度)、台湾暖流以及生物生产等。调查海域2012年7月海-气FCO2平均为(-6.410±7.486)mmol/(m2·d),表现东海在夏季是大气CO2的汇区,区域碳汇强度由强到弱依次为:长江冲淡水区(CDW)、黄东海混合水区(YEMW)、陆架咸淡水混合区(SMW)、近岸上升流区(CUW)和台湾暖流区(TWCW),东海夏季每日吸收大气CO2(以C计)约(18.3±19.8)kt。结合历史资料分析发现,近十几年来东海夏季碳汇强度有增强趋势,CDW区的海-气界面CO2通量平均年增速为-0.814mmol/(m2·d),即海水吸收大气二氧化碳每年增加约54.6kt,是夏季东海碳汇增加的最主要贡献者。     

二种核糖体型的多环马格里夫藻(Margalefidinium polykrikoides)的形态和超微结构比较及分子系统学分析

多环马格里夫藻是一种世界性广泛分布的有毒有害藻华原因种。过去30多年里多环马格里夫藻藻华在许多国家频繁暴发且呈快速扩散趋势。过去的研究根据不同地理来源种群在核糖体大亚基基因序列的显著差别,将其分成4种不同核糖体型(ribotype),即东亚型、菲律宾型、美国/马来西亚型和地中海型。但是,不同核糖体型的种群在形态和超微结构上是否也存在可辨识差异尚未见深入研究。为此,本文对从中国青岛胶州湾、美国东海岸和马来西亚近海分离的三株多环马格里夫藻(中国株MPJZBC3、美国株CP1和马来西亚株MPCoKK23)的细胞表面形态和超微结构进行了比较研究,并进一步基于核糖体大亚基序列进行了分子系统学分析。结果首先证明了分离自胶州湾的多环马格里夫藻属于东亚核糖体型,而美国株和马来西亚株均属美国/马来西亚型(中国株与美国株及马来西亚株在1523个碱基的核糖体大亚基序列上相似性为93.6%)。但是,在所有常用的具有分类学意义的细胞形态学和超微结构特征上[细胞大小、单细胞或群体及群体细胞数、上下锥形状、横沟位移度(绕细胞圈数)、纵沟形态、顶沟形态、细胞核位置与形状、染色体形状与数目、叶绿体的形状、结构、数目及分布、淀粉核形态等],中国株与美国株和马来西亚株(也即东亚核糖体型和美国/马来西亚核糖体型)都没有明显可区分的差别。因此,我们认为应该在生活史、休眠孢囊形态和生理学特征(如毒素种类及毒性强弱)以及性别相容性(sexualcompatibility)等方面开展进一步比较研究,以获得对不同核糖体型种群的识别性状。在现阶段有害藻华的野外监测中,尤其是对于不同核糖体型种群可能造成的生物入侵的监测和追溯,多环马格里夫藻的鉴定尚必须以核糖体基因序列作为可靠的判决依据。     

Temporal and depth distribution of microepiphytes on Posidonia oceanica (L.) Delile leaves in a meadow off Tunisia

A survey on the epiphytic microorganisms growing on Posidonia oceanica leaves was conducted along a depth transect along the coast of Eastern Tunisia (Mahdia). Samples were collected by SCUBA diving at depths of 3, 5, 10 and 12 m in July 2008 and January 2009. A total of 58 microepiphyte taxa were identified. Multivariate analyses revealed temporal and spatial variation of the abundance of epiphytic microalgae. Water motion, light availability, temperature and motility of species seem to be responsible of temporal and bathymetric variations of epiphytic microalgae. Unlike diatoms, dinoflagellates were more abundant in deep waters, suggesting that they are more vulnerable to hydrodynamics. The significant correlation between leaf area index and abundance of epiphytic species indicates that the phenological parameters of the host plant influence the abundance of the epiphytic microorganisms. Among the epiphytic dinoflagellates, our data showed a great number of potentially toxic species (Alexandrium minitum, Amphidinium carterae, Karenia selliformis, Coolia monatis, Karlodinium veneficum, Ostreopsis siamensis, Prorocentrum concavum, Prorocentrum minimum, Prorocentrum rathymum and Prorocentrum lima). These species were more abundant in the deep station under more sheltered conditions than found at inshore shallower stations, which are subjected to high water motion.     

不同材料塑料挂板对海月水母浮浪幼虫附着的影响

通过野外海区挂板的方法,探讨高密度聚乙烯(HDPE)、低密度聚乙烯(LDPE)、聚氯乙烯(PVC)、聚苯乙烯(PS)、聚对苯二甲酸乙二酯(PET)和聚氨酯(PUR)6种不同材料的塑料挂板对海月水母(Aurelia sp.1)附着的影响,分析不同塑料挂板表面粗糙度和海月水母附着的关系.研究结果表明:海月水母浮浪幼虫在夏末秋初可以附着在人工投放的塑料挂板附着基上,表明海岸带工程造成的人工附着基增多可能为海月水母的附着提供便利条件;海月水母螅状幼体在不同材料塑料挂板上的附着率有明显差异,PET、PUR和PVC塑料挂板海月水母螅状幼体附着率显著大于其他3种塑料挂板,其中PUR塑料挂板海月水母螅状幼体附着率最大,附着率为3.21±0.74 ind./cm2,HDPE塑料挂板海月水母螅状幼体附着率最低为0.26±0.08 ind./cm2;海月水母浮浪幼虫附着率与不同材料表面的粗糙度并不显著相关,表明塑料挂板材料的表面粗糙度并不是影响海月水母螅状幼体附着率的关键因子,而不同材料塑料挂板上形成的生物膜可能也对海月水母浮浪幼虫的附着产生影响.研究结果可为我国近岸海域有害水母海月水母暴发和防控研究提供一定的重要参考数据.     

Distribution of zooplankton in the Barents Sea in August 2006

Forty-two mesozooplankton samples were collected in the Barents Sea during the cruise of the R/V Dal’nie Zelentsy in August 2006. In total, 72 taxa of planktic animals were found. The minimal average mesozooplankton abundance was noted in the Murmansk coastal waters in the south of the sea (154 ind./m³), while the maximal was noted in the Arctic waters (1533 ind./m³). The average wet biomass varied from 32 to 830 mg/m³. The zooplankton abundance and biomass exceeded the relevant average long-term parameters by 1.5–2 times and by 1.2–1.4 times, respectively. The mean biodiversity (Shannon’s index) of the zooplankton communities was low: H′ = 1.62 ± 0.104 bit/ind.     

基于水色遥感的黄、东海叶绿素a浓度季节和年际变化特征分析

海洋叶绿素a浓度是衡量海洋浮游植物的生物量和富营养化程度的最基本指标之一。黄、东海叶绿素a浓度年际变化显著,其影响因素需深入分析。本文依据黄、东海的地理位置、水深和生态特征将其分为5个区域进行研究。由5个区域叶绿素a浓度的季节变化可以看出,水华发生早晚依次是黄海西岸—北黄海中部—南黄海中部—东海陆架区—东海近岸海区。从年际变化可以看出,除东海陆架外,其它4个区域的变化幅度均较大。在冬季和夏季,5个区域的基础生物量在2008年均达到最低;在春季和秋季,黄、东海近岸和北黄海中部的年际变化较大,5个区域在2006年春季均达到最高;2009年秋季较其它年份均低。5个区域基础生物量由高到低为:黄、东海近岸较高,然后是北黄海中部和南黄海中部,东海陆架最低。从与水温、风速和有效光合辐射的相关分析来看,浮游植物生长的年际变化受海面风速的影响较大。近岸区域水体混合均匀,营养盐丰富,风速较小时水体稳定有利于浮游植物生长,而水深较深区域,风速较大时,营养盐易补充到表层,有利于浮游植物生长。     

Longitudinal patterns of spring-intermonsoon phytoplankton biomass, species compositions and size structure in the Bay of Bengal

Vertical distributions of phytoplankton biomass, compositions and size structure were investigated during the spring-intermonsoon (April 22 to 30) of 2010 along transact 10°N of the Bay of Bengal, northern Indian Ocean. Surface phytoplankton biomass (Chl a) was (0.065§0.009) μg/L, being greater than 80% of which was contributed by pico-phytoplankton (<3 μm). The Chl a concen- tration vertically increased to the maximal values at deep chlorophyll maximum (DCM) layer that shoaled eastwards from 75 to 40 m. The Chl a biomass at DCM layer generally varied between 0.2 and 0.4 μg/L, reaching the maximum of 0.56 μg/L with micro-phytoplankton cells (>20 μm) accounting for 58% and nano- (3-20 μm) or pico-cells for 15% and 27%, respectively. In particular, the cells concentration coupling well with phosphate level was observed at middle layer (75-100 m) of 87° to 89°E, dominated by micro-cells diatoms (e.g., Chaetoceros atlanticus v. neapolitana, Chaetoceros femur and Pseudonitzschia sp.) and cyanobacteria (i.e., Trichodesmium hildebrandtii), with the cells concentration reached as high as 4.0×10⁴ and 4.3×10⁴ cells/L. At the rest of the trans- act however, dino°agellates (e.g., Amphisdinium carterae and Prorocentrum sp.) were the dominant species, with the cells concentration varying from 0.3×10³ to 6.8×10³ cells/L. Our results also in- dicate that the regulation of large cells (micro-, nano-) on phytoplankton biomass merely occurred at DCM layer of the Bay.     

Similarity of electrophoretic dissolved protein spectra from coastal to pelagic seawaters

Dissolved proteins in seawater samples collected from a coastal area of Tokyo Bay, Sagami Bay and a location off the Kuroshio Current were investigated by one-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and high resolution two-dimensional electrophoresis (2-DE). Four to nine protein bands were detected in SDS-PAGE in the apparent molecular weight (MW) range from 12 kilo Dalton (kDa) to 49 kDa. The 2-DE technique distinguished 10 to 46 protein spots exhibiting isoelectric point (pI)/MW ranging 4.3–9.2/12–63 kDa. The elecrophoretic patterns were similar between the coastal and pelagic samples, as well as previously reported patterns from various pelagic areas. The close similarity of electrophoretic mobility on both SDS-PAGE and 2-DE gels indicates the compositional homogeneity of dissolved proteins in seawater throughout a broad range of marine environments. Proteinaceous dissolved organic matter (DOM) that was unresolved and smeared staining characteristics on both SDS-PAGE and 2-DE gels was first observed in Tokyo Bay waters in the present study and its possible sources are discussed. Although the two protein species, 48 kDa and 39 kDa proteins, have been identified as homologues of Porin P and low molecular weight-alkaline phosphatase of Pseudomonas aeruginosa PAO1, respectively, four strains of P. aeruginosa and two species of Pseudomonas spp. have been newly identified as the source organisms of these proteins using the N-terminal amino acid sequence data determined in previous studies.     

中国南海四种凯伦藻种间作用与溶血活性初步研究

凯伦藻属种类广布于世界沿海海域甚至大洋，属广域分布种。该属下多个种类曾在全球近岸海域暴发有毒有害赤潮，造成巨大的经济损失，其中不乏由多种凯伦藻同时混合形成赤潮的现象存在。在2016年香港海域的一次凯伦藻赤潮中，本团队从赤潮海水中分离出了米氏凯伦藻（Karenia mikimotoi）、长沟凯伦藻（K.longicanalis）、鞍形凯伦藻（K.selliformis）和蝶形凯伦藻（K.papilionacea）4种凯伦藻。本研究以此4种凯伦藻进行单种藻及多种藻混合样品的培养和溶血活性研究，以探究复合型凯伦藻的种间作用及溶血活性。结果表明，4种凯伦藻间存在种间相互作用，长沟凯伦藻会促进蝶形凯伦藻的生长，鞍形凯伦藻和米氏凯伦藻会抑制长沟凯伦藻生长。4种凯伦藻对兔血红细胞均有明显溶血活性，长沟凯伦藻溶血活性最强为46.36%±1.02%。每种凯伦藻与其他凯伦藻混合培养3天后，对兔血的溶血活性会明显增加，其中含4种凯伦藻的混合组溶血活性最高，为57.05%±1.13%。     

热带北太平洋西部固氮速率及固氮微生物组成

In the present study, we report N_2 fixation rate(~(15)N isotope tracer assay) and the diazotroph community structure(using the molecular method) in the western tropical North Pacific Ocean(WTNP)(13°–20°N, 120°–160°E). Our independent evidence on the basis of both in situ N_2 fixation activity and diazotroph community structure showed the dominance of unicellular N_2 fixation over majority of the WTNP surface waters during the sampling periods.Moreover, a shift in the diazotrophic composition from unicellular cyanobacteria group B-dominated to Trichodesmium spp.-dominated toward the western boundary current(Kuroshio) was also observed in 2013. We hypothesize that nutrient availability may have played a major role in regulating the biogeography of N_2 fixation.In surface waters, volumetric N_2 fixation rate(calculated by nitrogen) ranged between 0.6 and 2.6 nmol/(L·d) and averaged(1.2±0.5) nmol/(L·d), with 10 μm size fraction contributed predominantly(88%±6%) to the total rate between 135°E and 160°E. Depth-integrated N_2 fixation rate over the upper 200 m ranged between 150 μmol/(m~2·d)and 480 μmol/(m~2·d)(average(225±105) μmol/(m~2·d). N_2 fixation can account for 6.2%±3.7% of the depthintegrated primary production, suggesting that N_2 fixation is a significant N source sustaining new and export production in the WTNP. The role of N_2 fixation in biogeochemical cycling in this climate change-vulnerable region calls for further investigations.     

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.     

The Air-Sea Exchange of CO2 in the East Sea (Japan Sea)

During CREAMS expeditions, fCO₂ for surface waters was measured continuously along the cruise tracks. The fCO₂ in surface waters in summer varied in the range 320–440 μatm, showing moderate supersaturation with respect to atmospheric CO₂. In winter, however, fCO₂ showed under-saturation of CO₂ in most of the area, while varying in a much wider range from 180 to 520 μatm. Some very high fCO₂ values observed in the northern East Sea (Japan Sea) appeared to be associated with the intensive convection system developed in the area. A gas-exchange model was developed for describing the annual variation of fCO₂ and for estimating the annual flux of CO₂ at the air-sea interface. The model incorporated annual variations in SST, the thickness of the mixed layer, gas exchange associated with wind velocity, biological activity and atmospheric concentration of CO₂. The model shows that the East Sea releases CO₂ into the atmosphere from June to September, and absorbs CO₂ during the rest of the year, from October through May. The net annual CO₂ flux at the air-sea interface was estimated to be 0.032 (±0.012) Gt-C per year from the atmosphere into the East Sea. Water column chemistry shows penetration of CO₂ into the whole water column, supporting a short turnover time for deep waters in the East Sea. This revised version was published online in August 2006 with corrections to the Cover Date.