Temporal variation in phytoplankton composition related to water mass properties in the central part of Sagami Bay

Temporal variations in water mass properties and the composition of phytoplankton pigments in the central part of Sagami Bay were investigated by monthly observations from June 2002 to May 2004. Eleven pigments were quantified using high-performance liquid chromatography (HPLC) from 100%, 20%, and 5% light depths relative to the surface; the class-specific composition of phytoplankton community was then obtained by CHEMTAX analysis. The study area was influenced by the Kuroshio water for most of the observation period. The mean contribution of diatoms in all samples was relatively low (29%), while that of flagellates, mainly chlorophytes or cryptophytes, was quite high (60%). The phytoplankton composition at the three depths was uniform throughout the observation period, indicating that the vertical structure of the phytoplankton community did not develop significantly over time. A distinct temporal pattern was observed: flagellates dominated during the summer of 2002 and the winters of 2002–2003 and 2003–2004, while diatoms dominated during the summer of 2003. This pattern was associated with water mass changes. The community in the summer of 2003 was influenced by coastal water. While no distinct spring bloom of phytoplankton was observed, a weak increase in chlorophyll a was observed during the spring of 2004. Ocean color satellite data showed that fluctuations in chlorophyll a concentrations at time scales much shorter than a month occurred during the spring of 2003 and that the elevations in chlorophyll a levels were not continuous. The fluctuations were probably associated with rapid flushing by the Kuroshio water, which has low chlorophyll a content.     

印尼爪哇上升流海域次表层叶绿素最大值层的浮游植物色素分布特征

Upwelling occurs on the coast of Java between June and October, forced by local alongshore winds associated with the southeasterly monsoon. This causes variations in phytoplankton community composition in the upwelling zone compared with the surrounding offshore area. Based on pigments analysis with subsequent calculations of group contributions to total chlorophyll a(Chl a) using CHEMTAX, we studied the distribution and composition of phytoplankton assemblages in the subsurface chlorophyll maximum along the south coast of Java and the influence of upwelling. Nineteen phytoplankton pigments were identified using high-performance liquid chromatography, and CHEMTAX analysis associated these to ten major phytoplankton groups. The phytoplankton community in the coastal area influenced by upwelling was characterized by high Chl a and fucoxanthin concentrations, indicating the dominance of diatoms. In contrast, in the offshore area, the Chl a and fucoxanthin concentrations declined to very low levels and the community was dominated by haptophytes represented by 19′-Hexanoyloxyfucoxanthin. Accordingly, microphytoplankton was found to be the major size class in the coastal area influenced by upwelling, while nanophytoplankton was most abundant in the offshore area. Low concentrations of other accessory pigments indicated less contribution from dinoflagellates,prasinophytes, chlorophytes and cryptophytes. Photo-pigment indices revealed that photosynthetic carotenoids(PSCs) were the largest component of the pigment pool, exceeding the proportion of Chl a, with the average PSCTP up to 0.62. These distribution trends can mainly be explained by phytoplankton adaption strategies to upwelling and subsurface conditions by changing species composition and adjusting the pigment pool.     

Variability of phytoplankton absorption in the northern South China Sea: influence of the size structure and pigment composition of algal populations

Data from three cruises conducted in the Zhujiang River (ZR), coastal waters of Guangdong (CWGD) and the northern South China Sea (NSCS) during 2003 and 2004 were examined for assessing the relative importance of pigment composition and packaging effect in modifying the specific absorption coefficients of phytoplankton. The three survey regions differ widely in their phytoplankton community with large cells dominating the ZR and CWGD waters and small cells dominating the NSCS region. Variations in the size structure and the accessory pigments have much effect on the chlorophyll a-specific absorption coefficient of phytoplankton. The size index accounted for about 42% and 33% of the variation of the specific absorption coefficient at 440 and 675 nm, respectively. Using the multiple regression analysis approach, pigment concentrations for each sample were calculated. The accessory pigments other than chlorophyll a contribute to absorption mainly in the blue-to-green region of the spectrum and their absorptions account for about 44%, 43% and 53% on the average of the total phytoplankton absorption at 440 nm for the ZR, CWGD and NSCS regions. Among the accessory pigments, the photosynthetic carotenoids (noted PSC) play a dominant role in the ZR and CWGD waters, while in the NSCS the nonphotosynthetic carotenoids (noted PPC) as well as PSC have important contributions. Because the variations of both the size structure and accessory pigments in algal populations contributed to the variability of the specific absorption coefficient in the study regions, these factors may be considered explicitly in future bio-optical algorithms to derive chlorophyll a concentration more accurately.     

南流江河口区春季浮游植物群落结构组成与分布特征

通过2016年3月底现场航次11个站点的调查,应用反相高效液色谱（RP-HPLC）并结合二极管阵列检测器分析技术,分析了春季广西南流江河口区浮游植物光合色素组成,进而由CHEMTAX软件估算全粒级浮游植物的群落结构。结果表明:春季含量较高的浮游植物特征光合色素含量以叶绿素b最高,其次为岩黄藻素;浮游植物的优势类群为隐藻,其次为绿藻和硅藻,它们分别平均占据了浮游植物生物量的54.95%、23.36%和17.37%,其他藻类所占比例很低。南流江河口区浮游植物群落结构东西部入海分支有较大差异:东部分支营养盐较西部分支低,隐藻所占生物量比例最高,其次为绿藻和硅藻,浮游植物群结构与分布受营养盐因素影响较大;西部分支营养盐含量明显比东部分支高,绿藻和硅藻的所占比例有所提升,隐藻的生物量所占比则有所下降,浮游植物群落结构与分布受非营养盐因素的影响较大。南流江河口区浮游植物生物量和群落结构除了受营养盐影响外,还与浊度、盐度等密切相关,表明南流江浊度增加已明显影响着生态系统结构与功能,需要密切关注和进一步研究。     

西赤道太平洋暖池区光合色素分布及其对浮游植物群落的指示作用

利用光合色素的生物标志性可以在"纲"水平上表征浮游植物群落结构。依托大洋科学考察第20航次和21航次,通过对西赤道太平洋不同区域5个站位的HPLC藻类色素分析及CHEMTAX程序因子分析,获取了暖池区光合色素及浮游植物群落的垂直分布信息。结果显示在寡营养的暖池区,玉米黄素(Zeaxanthin)及乙二烯叶绿素a(DV Chl a)与叶绿素a浓度呈显著的正相关,浮游植物群落结构以蓝细菌、原绿球藻及定鞭金藻为优势藻纲,按对生物量的贡献率原绿球藻大于蓝细菌大于定鞭金藻的。蓝细菌和原绿球藻分布在真光层不同深度,而在营养盐丰富的次表层优势浮游藻类为定鞭金藻。     

Summer phytoplankton pigments and community composition related to water mass properties in the Gulf of Gabes

Variations in phytoplankton pigments and community composition were examined in the Gulf of Gabes in relationship to water mass properties, characterised by the influence of the Modified Atlantic Water and by the thermal stratification. Data were collected on board the R/V Hannibal during July 2005.Distinct water masses were identified using cluster analysis of temperature–salinity (T–S) characteristics. Three major clusters appeared based on the combined effects of temperature and salinity. The first cluster was identified as the cool and less salty bottom Modified Atlantic Water (MAW). The warmer and saltier Mediterranean Mixed Water (MMW) represented the second cluster. The third cluster was the Transition Water (TW) separating the two previous clusters.The pigment and taxonomic composition of these water masses were examined. Chlorophyll a was rather low (<200 ng l⁻¹). Chlorophyll b was generally the most abundant accessory pigment and fucoxanthin dominated the accessory pigments in the MAW. Proportions of chlorophyll a associated with different phytoplankton classes were estimated using CHEMTAX software, and did not present significant variations among water groups. The results pointed out variations in the relative contribution of each phytoplankton taxa in each station group. Chlorophytes and prasinophytes accounted for 65% of chlorophyll a in the MMW. Diatoms and chlorophytes were relatively abundant in the MAW contributing to almost 63% of chlorophyll a. An unstructured community, slightly dominated by prasinophytes, chlorophytes and cryptophytes, characterised the TW. Different trophic statuses were observed in these water masses, the MMW and the MAW being characterised by mesotrophy, while an oligotrophy was observed in the TW. Nutrient availability, particularly the P-limitation supported by the summer stratification, as revealed by the high N:P ratio (greater than 20), seems to enhance the development of small-sized phytoplankton, thereby supporting the regenerated production.     

东南亚近岸海区浮游植物光合色素和群落组成—印度尼西亚贯穿流和吉兰丹河口区的比较研究

Water samples were collected in order to study the spatial variation of photosynthetic pigments and phytoplankton community composition in the Lembeh Strait(Indonesia) and the Kelantan River Estuary(Malaysia)during July and August 2016, respectively. Phytoplankton photosynthetic pigments were detected using high performance liquid chromatography combining with the CHEMTAX software to confirm the Chl a biomass and community composition. The Chl a concentration was low at surface in the Lembeh Strait, which it was 0.580–0.682 μg/L, with the average(0.620±0.039) μg/L. Nevertheless, the Chl a concentration fluctuated violently at surface in the Kelantan River Estuary, in which the biomass was 0.299–3.988 μg/L, with the average(0.922±0.992) μg/L. The biomass at bottom water was higher than at surface in the Kelantan River Estuary, in which the Chl a concentration was 0.704–2.352 μg/L, with the average(1.493±0.571) μg/L. Chl b, zeaxanthin and fucoxanthin were three most abundant pigments in the Lembeh Strait. As a consequence, phytoplankton community composition was different in the two study areas. In the Lembeh Strait, prasinophytes(26.48%±0.83%) and Synechococcus(25.73%±4.13%) occupied ～50% of the Chl a biomass, followed by diatoms(20.49%±2.34%) and haptophytes T8(15.13%±2.42%). At surface water in the Kelantan River Estuary, diatoms(58.53%±18.44%)dominated more than half of the phytoplankton biomass, followed by Synechococcus(27.27%±14.84%) and prasinophytes(7.00%±4.39%). It showed the similar status at the bottom water in the Kelantan River Estuary,where diatoms, Synechococcus and prasinophytes contributed 64.89%±15.29%, 16.23%±9.98% and 8.91%±2.62%,respectively. The different phytoplankton community composition between the two regions implied that the bottom up control affected the phytoplankton biomass in the Lembeh Strait where the oligotrophic water derived from the West Pacific Ocean. The terrigenous nutrients supplied the diatoms growing, and pico-phytoplankton was grazed through top down control in the Kelantan River Estuary.     

Characterisation of water masses and phytoplankton nutrient limitation in the East Australian Current separation zone during spring 2008

This study focuses on the comparison of oceanic and coastal cold-core eddies with inner-shelf and East Australian Current (EAC) waters at the time of the spring bloom (October 2008). The surface water was biologically characterised by the phytoplankton biomass, composition, photo-physiology, carbon fixation and by nutrient-enrichment experiments. Marked differences in phytoplankton biomass and composition were observed. Contrasted biomarker composition suggests that biomarkers could be used to track water masses in this area. Divinyl chlorophyll a, a biomarker for tropical Prochlorophytes, was found only in the EAC. Zeaxanthin a biomarker for Cyanophytes, was found only within the oceanic eddy and in the EAC, whereas chlorophyll b (Chlorophytes) was only present in the coastal eddy and at the front between the inner-shelf and EAC waters.This study showed that cold-core eddies can affect phytoplankton, biomass, biodiversity and productivity. Inside the oceanic eddy, greater phytoplankton biomass and a more complex phytoplankton community were observed relative to adjacent water masses (including the EAC). In fact, phytoplankton communities inside the oceanic eddy more closely resembled the community observed in the inner-shelf waters. At a light level close to half-saturation, phytoplankton carbon fixation (gC d⁻¹) in the oceanic eddy was 13-times greater than at the frontal zone between the eddy and the EAC and 3-times greater than in the inner-shelf water. Nutrient-enrichment experiments demonstrated that nitrogen was the major macronutrient limiting phytoplankton growth in water masses associated with the oceanic eddy. Although the effective quantum yield values demonstrate healthy phytoplankton communities, the phytoplankton community bloomed and shifted in response to nitrogen enrichments inside the oceanic eddy and in the frontal zone between this eddy and the EAC. An effect of Si enrichment was only observed at the frontal zone between the eddy and the EAC. No response to nutrient enrichment was observed in the inner-shelf water where ambient NO_x, Si and PO₄ concentrations were up to 14, 4 and 3-times greater than in the EAC and oceanic eddy. Although results from the nutrient-enrichment experiments suggest that nutrients can affect biomass and the composition of the phytoplankton community, the comparison of all sites sampled showed no direct relationship between phytoplankton biomass, nutrients and the depth of the mixed layer. This is probably due to the different timeframe between the rapidly changing physical and chemical oceanography in the separation zone of the EAC.     

应用光合色素标记物研究2001年2～6月厦门西海域浮游植物群落结构

利用反相高效液相色谱（RP-HPLC）对厦门西海域2001年2～6月的浮游植物色素进行了测定,并首次运用CHEMTAX软件对该海域进行了浮游植物群落组成的分析,同时分析了环境因子对群落组成的作用.我们首先改进了RP-HPLC分离方案,分离的时间缩短了近1/3,达到了提高分离效率的目的.利用改进后的RP-HPLC方案进行色素分析显示,厦门西海域2001年2～6月期间,主要的特征色素是岩藻黄素（fucoxanthin）、19’-丁酰基氧化岩藻黄素（19’-butanoyloxyfucoxanthin）、19’-己酰基氧化岩藻黄素（19’-hexanoyloxyfucoxanthin）和多甲藻素（peridinin）,月平均含量分别在267.824～655.076、20.118～126.764、65.693～214.115、26.955～203.927μg/m3的范围变动.CHEMTAX计算的结果进一步表明：硅藻是主要优势类群,其次是定鞭金藻和甲藻,分别占总生物量的36.14%～79.27%、4.50%～37.40%和4.83%～21.37%.总生物量从2月到6月呈增长趋势,温度是主要的决定因子.硅藻和定鞭金藻所占生物量的份额呈相反趋势变化,表明种间竞争也是重要的因素之一.     

Effects of a thermal discharge from a nuclear power plant on phytoplankton and periphyton in subtropical coastal waters

Effects of elevated water temperatures and residual chlorine from a thermal discharge at a coastal nuclear power plant on the biomass and productivity of periphyton and phytoplankton were determined in subtropical Taiwan. Phytoplankton chlorophyll a, but not productivity, was significantly lower in the outlet region than in the intake region. Periphyton chlorophyll a was significantly greater in the outlet region than in the intake region. Nevertheless, periphyton productivity was negatively correlated with water temperature in the outlet region. A distinct difference in periphyton community composition was also detected between the two regions. Chlorination experiments showed that a chlorine concentration of 0.2 ppm greatly suppressed phytoplankton productivity, regardless of whether the water temperature was elevated or not. However, periphyton productivity was little influenced by a chlorine concentration of < 0.5 ppm. Our results suggest that phytoplankton productivity was greatly affected by residual chlorine, but periphyton productivity was more affected by elevated water temperatures.     

福建沿岸不同海区夏季浮游植物的组成与分布

结合福建省“908专项”,于2006年7～8月对福建省沿岸海域水采浮游植物的种属组成、数量分布、生物量进行了大面积科学调查．结果表明,福建沿岸海域浮游植物隶属于6门57属127种,其中硅藻47属107种,甲藻5属15种,蓝藻1属1种,金藻2属2种,隐藻1属1种,裸藻1属1种．硅藻类在种类和数量上均占主导地位,优势种主要是柔弱伪菱形藻（Pseudo—nitzschia delicatissima）、中肋骨条藻（Skeletonema costatum）、旋链角毛藻（Chaetoceros curvisetus）、菱形海线藻（Thalassionema nitzschioides）等．硅藻类广布,甲藻类在闽东海域及东山沿岸分布较多,蓝藻类检出率降低,裸藻类和金藻类检出率增高．表层浮游植物平均细胞密度为3222．59×10^4ind／dm^3,数量分布态势为近岸高、外海低,阂东和闽南高、闽中低．叶绿素a及优势类群的分布与数量分布基本一致．福建沿岸海域赤潮生物种类较多,是引发赤潮的潜在生物因素,一些赤潮生物已在闽南、闽东沿岸局部海域成为优势种．     

Covariance among North Sea ecosystem state indicators during the past50 years — Contrasts between coastal and open waters

Regime shift and principal component analysis of a spatially disaggregated database capturing time-series of climatic, nutrient and plankton variables in the North Sea revealed considerable covariance between groups of ecosystem indicators. Plankton and climate time-series span the period 1958–2003, those of nutrients start in 1980. In both regions, the period from 1989 to 2001 identified in principal component 1 had warmer surface waters, higher Atlantic inflow and stronger winds, than the periods before or after. However, it was preceded by a regime shift in both open (PC2) and coastal (PC3) waters during 1977 towards more hours of sunlight and higher water temperature, which lasted until 1997. The relative influence of nutrient availability and climatic forcing differed between open and coastal North Sea regions. Inter-annual variability in phytoplankton dynamics of the open North Sea was primarily regulated by climatic forcing, specifically by sea surface temperature, Atlantic inflow and co-varying wind stress and NAO. Coastal phytoplankton variability, however, was regulated by insolation and sea surface temperature, as well as Si availability, but not by N or P. Regime shifts in principal components of hydrographic and climatic variables (explaining 55 and 61% of the variance in coastal and open water variables) were detected using Rodionov's sequential t-test. These shifts in hydroclimatic variables which occurred around 1977, 1989, 1997 and 2001, were synchronized in open and coastal waters, and were tracked by open water chlorophyll and copepods, but not by coastal plankton. North–central–south or open-coastal spatial breakdowns of the North Sea explained similar amounts of variability in most ecosystem indicators with the exception of diatom abundance and chlorophyll concentration, which were clearly better explained using the open-coastal configuration.     

北冰洋中心区表层淡化层的藻类色素组成

季节性海冰融化在北冰洋中心区表层形成淡水层,影响了浮游植物的类群。研究发现岩藻黄素（Fuco,指示硅藻）是冰芯底部检测到的主要光合色素,叶黄素（Lut）和叶绿素b （Chl b）（指示绿藻）是冰水界面浓度最高的类胡萝卜素。海冰底部硅藻占据了绝对的优势,但在冰水界面藻类类群转变了以绿藻为主的结构。冰下水中,浮游植物群落随着深度的增加,由绿藻为主快速转变为以硅藻为主,盐度可能是导致这种变化的原因。     

枯水期钦州湾浮游植物群落结构组成与分布特征

应用浮游植物特征光合色素的分析方法,研究了2011年枯水期钦州湾浮游植物的结构组成与分布特征。结果表明:枯水期含量较高的浮游植物光合色素按含量高低依次为叶绿素a、岩藻黄素、叶绿素b、青绿素和多甲藻素,其他特征光合色素的含量很低。经CHEMTAX对光合色素转化计算,枯水期普遍检出的浮游植物类群为硅藻、青绿藻和甲藻,是枯水期浮游植物的优势类群,其生物量的平均值(±标准差)分别为(2.36±2.38)μg/L、(0.87±0.53)μg/L、(0.13±0.14)μg/L,变化范围为0.18~7.45μg/L、0.10~1.80μg/L和0.02~0.60μg/L。硅藻、青绿藻和甲藻占枯水期浮游植物生物量比例的平均值(±标准差)分别为59%±21%、30%±16%、6%±4%,占比变化范围为29%~96%、1%~53%和0.4%~14%,其他藻类所占比例很低。河口和外湾靠外海域两个区域以硅藻为优势类群,内湾及外湾近岸硅藻和青绿藻共同为优势类群。河流营养盐输入量和比例的不同决定了钦州湾河口海区浮游植物群落结构的差异,大面积贝类养殖导致了内湾至外湾近岸海区硅藻比例的降低,而外湾水温的增加引起暖水性硅藻大量增长成为优势类群,在温度进一步增加和营养盐持续输入等条件下存在会发生硅藻赤潮的风险。     

乐清湾海域浮游动物群落分布的季节变化特征及其环境影响因子

2006年10月、2007年1月、4月及7月对乐清湾海域浮游动物群落的种类组成、优势种、生态类群、水平分布的季节性变化特征进行了调查,分析了浮游动物群落分布与环境因子的关系。结果表明,在调查海域共鉴定出浮游动物82种(包括浮游幼体11种),隶属于15大类,其中秋季为46种、夏季为42种、春季为25种和冬季为16种。乐清湾浮游动物可分为近岸低盐类群、暖水性近海类群、暖温带近海类群和暖水性广布类群4个生态类群,其中近岸低盐类群在全年均占优势,其它类群则呈现明显的季节变化。中华哲水蚤Calanus sinicus、真刺唇角水蚤Labidocera euchaeta、针刺拟哲水蚤Paracalanus aculeatus和背针胸刺水蚤Centropages dorsispinatus为调查海域主要优势种。浮游动物生物量年平均值为82.7mg/m3,其大小依序为:夏季(121.1mg/m3)>秋季(119.2mg/m3)>春季(48.5mg/m3)>冬季(42.2mg/m3);丰度年平均值为82.1个/m3,其大小依序为:夏季(193.4个/m3)>秋季(73.7个/m3)>春季(53.4个/m3)>冬季(9.8个/m3)。相同季节浮游动物生物量和丰度的平面分布趋势类似,季节间则存在明显差异。相关性分析结果表明,浮游动物物种数与水温、盐度、叶绿素a质量浓度和浮游植物细胞密度均呈极显著相关;丰度与水温、叶绿素a质量浓度和浮游植物细胞密度呈极显著相关;生物量与水温、叶绿素a质量浓度呈极显著相关。与历史资料相比,近30a来浮游动物数量呈下降趋势,但群落结构和组成没有发生明显改变。     

Contrasting oceanographic conditions and phytoplankton communities on the east and west coasts of Australia

The composition and dynamics of the phytoplankton communities and hydrographic factors that control them are described for eastern and western Australia with a focus on the Eastern Australian Current (EAC) and Leeuwin Current (LC) between 27.5° and 34.5°S latitude. A total of 1685 samples collected from 1996 to 2010 and analysed for pigments by high performance liquid chromatography (HPLC) showed the average TChla (monovinyl+divinyl chlorophyll a) concentration on the west coast to be 0.28±0.16 ??g L⁻¹ while it was 0.58±1.4 ??g L⁻¹ on the east coast. Both coasts showed significant decreases in the proportions of picoplankton and relatively more nanoplankton and microplankton with increasing latitude. On both coasts the phytoplankton biomass (by SeaWiFS) increased with the onset of winter. At higher latitudes (>27.5°S) the southeast coast developed a spring bloom (September) when the mean monthly, surface chlorophyll a (chla) concentration (by SeaWiFS) was 48% greater than on the south west coast. In this southern region (27.5-34.5°S) Synechococcus was the dominant taxon with 60% of the total biomass in the southeast (SE) and 43% in the southwest (SW). Both the SE and SW regions had similar proportions of haptophytes; ∼14% of the phytoplankton community. The SW coast had relatively more pelagophytes, prasinophytes, cryptophytes, chlorophytes and less bacillariophytes and dinophytes. These differences in phytoplankton biomass and community composition reflect the differences in seasonality of the 2 major boundary currents, the influence this has on the vertical stability of the water column and the average availability of nutrients in the euphotic zone. Seasonal variation in mixed layer depth and upwelling on the west coast appears to be suppressed by the Leeuwin Current. The long-term depth averaged (0-100 m) nitrate concentration on the west coast was only 14% of the average concentration on the east coast. Redfield ratios for NO₃:SiO₂:PO₄ were 6.5:11.9:1 on the east coast and 2.2:16.2:1 on the west coast. Thus new production (nitrate based) on the west coast was likely to be substantially more limited than on the eastcoast. Short term (hourly) rates of vertical mixing were greater on the east coast. The more stable water column on the west coast produced deeper subsurface chlorophyll a maxima with a 25% greater proportion of picoeukaryotes.     

厦门港海水光合色素特征

应用反相高效液相色谱（RP-HPLC）方法分析测定了冬季厦门鼓浪屿水文观测站两周内不同潮位海水中的光合色素的组成与含量，包括多甲藻素、19‘-已酰基氧化岩藻黄素、硅甲藻黄素、硅藻黄素、玉米黄素、叶绿素a、脱镁叶绿素a、β-胡萝卜素等。同时还实测了小于藻、金藻、盐藻、甲藻、角毛藻、螺旋藻等多个实验室培养藻种的色素组成。数据表明，不同种类的藻类具有不同的色素组成特征，从海水中光合色素的分析数据可推测其浮游植物主要种类组成情况。潮汐的水动力情况在色素组成变化上有所反映，表明港内外的乳游植物组成分布有梯度存在，且在特征上有所不同。     

2014年冬季热带西太平洋雅浦Y3海山光合色素分布及其对浮游植物群落的指示作用

应用高效液相色谱结合二极管阵列检测器分析技术,研究了西太平洋雅浦Y3海山区域2014年冬季浮游植物的光合色素组成。结果表明：100m以浅,玉米黄素（Zeax）是水柱中浓度最高的光合色素,浓度为22.64—84.31ng/L,叶绿素a（chl a）浓度在水柱中均值为（37±34） ng/L,在贫营养海区的数值范围内,水柱积分高值分布区与海山走向一致,二乙烯基叶绿素a（Dvchl a）和19''-丁酰氧岩藻黄素（19''BF）也是调查海区较高浓度的色素,在水柱中均值分别为（27±22）和（31±30） ng/L。其他色素新黄素（Neox）、叶黄素（Lute）、叶绿素b（chl b）、青绿素（Pras）平均水柱含量极低（<1.00ng/L）。通过CHEMTAX程序因子分析估算了浮游植物群落结构,调查区浮游植物群落以原绿球藻为优势藻,贡献率与环境因子不具有相关性,其次主要为蓝细菌和金藻,蓝细菌贡献率高值区分布在海山东南和东北侧0和30m水层,金藻贡献率高值区分布在75和100m水层,两者贡献率均与环境因子显著相关。     

Phytoplankton pigment distribution in relation to silicic acid, iron and the physical structure across the Antarctic Polar Front, 170°W, during austral summer

In order to study the factors controlling the phytoplankton distribution across the Antarctic Polar Frontal Region (PFR), surface pigment samples were collected during austral summer (January/February 1998) near 170°W. Both the Polar Front (PF) and the Southern Antarctic Circumpolar Current Front (SACCF) were regions of enhanced accumulation of phytoplankton pigments. The mesoscale survey across the PF revealed two distinct phytoplankton assemblages on either side of the front. The phytoplankton community was dominated by diatoms south of the PF and by nanoflagellates (primarily by prymnesiophytes) to the north. Surprisingly, chlorophyll a concentrations did not correlate with mixed-layer depths. However, an increase of the dominance of diatoms over prymnesiophytes was observed with decreasing mixed-layer depths. Despite this relationship, we conclude that the average light availability in the mixed layer was not an important factor influencing the shift in phytoplankton composition across the PF. Although no correlation was found between the surface distribution of the major phytoplankton taxa and dissolved iron or silicic acid concentrations, the location of the strongest vertical gradient in silicic acid and iron concentration coincides with the maximum abundance of diatoms. We conclude that the difference in taxonomic composition is a result of increased silicic acid and iron flux to the upper mixed layer as a result of the increased vertical gradient of these key nutrients south of the front.     

Inshore-offshore and vertical patterns of phytoplankton biomass and community composition in Santa Monica Bay, CA (USA)

Spatial gradients in biomass and community composition have important consequences for ecosystem structure and function. In this study, small-scale inshore-offshore (1-10 km) and vertical (1-50 m) patterns of microphytoplankton biomass and community composition are described, and the environmental controls of microphytoplankton biomass are evaluated in a coastal ecosystem of the Southern California Bight (SCB). During a two-year period, persistent inshore-offshore gradients in phytoplankton biomass and occasional inshore-offshore gradients in community composition, coincident with regional precipitation, were found, although the strength of the gradients varied between sampling periods. The chlorophyll a maximum was generally present between 15 and 45 m, the cell abundance maximum occurred in surface waters, and there was little evidence of vertical gradients in community composition. Variability in chlorophyll a concentrations was linked to variability in environmental parameters only after some rain and upwelling events. This study demonstrates that inshore-offshore patterns in phytoplankton biomass previously documented at large spatial scales (100-700 km) in the SCB can also persist at smaller scales (1-10 km), although the mechanisms for the gradients are likely to be different at the different spatial scales. The results provide a baseline data set that can be used to focus monitoring and management efforts in the SCB. In particular, this work shows that a limited number of sampling stations are sufficient for phytoplankton monitoring in Santa Monica Bay.