光照与东海近海中肋骨条藻(Skeletonema costatum)赤潮发生季节的关系

利用船基现场培养实验和模型计算的方法,研究了光照与东海近海春夏季均能发生中肋骨条藻赤潮的关系.结果表明,中肋骨条藻生长的最适光照强度(Iopt)随水温(t)的增加呈'慢升快降'的不对称'倒V'形变化特征,在25℃左右Iopt最大,为121.6 W.m-2,Iopt-t曲线符合Blanchard方程;由东海海表水温计算的中肋骨条藻Iopt的季节变化特征与东海海面光照强度、海水透明度的季节变化基本同步(R2=0.907±0.115,p<0.001),且滞后于海面光照强度2个月左右,这使春夏季海水中光照最适宜生长的水层均为全年最厚(6 m左右).可见,中肋骨条藻对光照的适应性很强,海区海水光照的适宜性是春夏季均能形成大规模中肋骨条藻赤潮的重要原因之一.

赤潮水体中胶体物质对赤潮异弯藻(Heterosigma akashiwo)和中肋骨条藻(Skeletonema costatum)生长的影响

2004年2月9~10日在胶州湾发生的柔弱几内亚藻(Guinardia delicatula)赤潮期间分别在3个典型赤潮站位采集表层水样,利用过滤(0.7μm)和切向超滤(1000Daltons)分离赤潮暴发水体中的胶体物质,分析了不同滤液及截留液的有机碳含量,并将赤潮异弯藻(Heterosigma akashiwo)和中肋骨条藻(Skeletonema costatum)在<1000Daltons的超滤液及具有不同含量胶体物质(1000Daltons^0.7μm)的截留液中进行培养。结果发现在发生柔弱几内亚藻赤潮期间水体中的溶解有机碳浓度会增加,特别是胶体有机碳浓度会成倍增长;在不同胶体含量海水中培养的赤潮异弯藻的最大生长率μmax和最大生物量Bf与对照组相比会随着胶体含量的增加而显著增大,而中肋骨条藻的最大生长率μmax和最大生物量Bf与对照组相比会随着胶体含量增加而显著降低,表明柔弱几内亚藻赤潮水体中的胶体物质对赤潮异弯藻的生长起促进作用,而对中肋骨条藻的生长起抑制作用。这说明柔弱几内亚藻在增殖过程中所产生的胶体物质具有他感作用,会影响其它微藻的生长,从而可能对柔弱几内亚藻赤潮的形成起重要作用。

粤东柘林湾中肋骨条藻(Skeletonema costatum)种群生态学

于2000年5月～2004年12月对粤东大规模养殖区柘林湾的赤潮藻中肋骨条藻（Skeletonema costatum）种群的时空分布进行了长达5a的调查。结果表明，中肋骨条藻种群密度的周年变动模式基本为双峰型，平面分布没有显著的空间差异。调查期间，中肋骨条藻种群密度的站位实测值为0～1．4×10^7cells／dm^3，总均值为3．3×10^5cells／dm^3，占浮游植物总细胞数的67．1％，为调查海区第1优势种。在总共1045份样品中，有中肋骨条藻出现的样品数为1020份。其中，种群密度大于10^6cells／dm^3的样品有65份，大于10^7cells／dm。则有4份。以大于10^6cells／dm^3为中肋骨条藻的赤潮密度标准，在调查期间至少于2000年、2003年发生4次赤潮。运用灰关联理论对中肋骨条藻种群密度与13个环境因子的关系进行排序分析发现，水温、pH值和浮游动物是影响柘林湾中肋骨条藻种群时空分布的关键因子。水温还与中肋骨条藻种群密度的对数值具极显著意义的线性关系，而达到赤潮密度的样品均落在24．5～32．0℃区间，即每年的5～9月份高温季节。由于柘林湾浮游动物的年高峰期也出现在高温季节，说明浮游动物摄食压力的存在可能是柘林湾中肋骨条藻赤潮发生的重要抑制因子。2004年调查海区中肋骨条藻种群密度和在浮游植物群落中的优势度骤然降低，可能与水体营养盐结构和Fe含量的变化有关。因此，长期调查与监测对于研究海湾生态学和赤潮发生机制是极为重要的。

塔玛亚历山大藻(Alexandrium tamarense)和中肋骨条藻(Skeletonema costatum)种间竞争及UV-B辐射胁迫对其影响

采用共培养的方法,研究了塔玛亚历山大藻和中肋骨条藻种群竞争关系对UV-B辐射增强的响应变化。结果表明,不同的接种密度对塔玛亚历山大藻和中肋骨条藻种群竞争有明显的影响。当塔玛亚历山大藻和中肋骨条藻的接种比例为A∶S=1∶4时,中肋骨条藻在竞争中占优势;当接种例为A∶S=1∶1时,虽然塔玛亚历山大藻在竞争中占优势,但也受到了中肋骨条藻的抑制;接种比例为A∶S=4∶1时,塔玛亚历山大藻的生长竞争优势更加明显。UV-B辐射增强(在预备实验的前提下,选择1.4J/m2)可改变塔玛亚历山大藻和中肋骨条藻种群竞争的关系,使塔玛亚历山大藻种群竞争能力降低,中肋骨条藻种群竞争能力大大提高,从而导致处理Ⅰ(A∶S=1∶4)中,中肋骨条藻在竞争优势更加明显,在处理Ⅱ(A∶S=1∶1)中,中肋骨条藻在竞争中占一定的优势。

The effect of UV-B radiation enhancement on the interspecific competition between Skeletonema costatum and Heterosigma akashiwo

The responses of the interspecific competition between Skeletonema costatum and Heterosigma akashiwo to UV-B radiation enhancement were studied by the co-culture method. The results showed that Heterosigma akashiwo exhibited inhibition on the growth of Skeletonema costatum, and with the increase of initial inoculation density of Heterosigma akashiwo, heavier inhibition on Skeletonema costatum appeared. Under different inoculation proportions, Heterosigma akashiwo could always be in predominance in competition with Skeletonema costatum. The UV-B radiation treatment could change the competition relationship between Skeletonema costatum and Heterosigma akashiwo, which could increase the competitive dominance of Skeletonema costatum and decrease the competitive dominance of Heterosigma akashiwo. When the inoculation proportions of Heterosigma akashiwo and Skeletonema costatum were H∶S=1∶4 and H∶S=1∶1,Skeletonema costatum was in predominance in this competition; however, Heterosigma akashiwo was in predominance when the inoculation proportion was H∶S=4∶1.

Maltivariate Analysis of the Occurring Process of Skeletonema costatum Red Tide in the Changjiang Estuary

Using the SAS software, the data of environmental factors vs. red tide biomass were analysed during the process of Skeletonema costatum red tide which broke out in the Changjiang Estuary on June 9～15, 1990. The results of the multivariate statistical analysis show that the environmental factors are similar in their developing and maintenance periods and that the values of environmental factors begin to be restored to normal levels during the disappearing period.The results obtained from using the methods of correlation, variable cluster and main component analyses are basically identical. The important factors contributing to the occurrence of this red tide are atmospherical pressure, water temperature, salinity, pH, No3-, -N, Po43--P and Fe, among which,salinity, Fe and PO43--P are the leading factors which have triggered the occurrence of the red tide as determined by the step-by-step regression analysis. Meanwhile, the linear discrimination functions have been established for the red tide. The environmental factor data of another occurring process of Skeletonema costatum red tide in the Changjiang Estuary have been chosen for red tide discrimination with satisfactory results.

长江口骨条藻属(Skeletonema)种类多样性及其形态(英文)

利用光镜和扫描电镜(SEM)观察对长江口骨条藻属种类进行观察,共发现两种已有种:中肋骨条藻Skeletonema costatum(Greville)Cleve,玛氏骨条藻Skeletonema marinoi Sarno et Zingone.中肋骨条藻细胞直径为6.3～15.1μm,贯壳轴长度为7.7～11μm;玛氏骨条藻细胞直径为4.6～11.2μm,贯壳轴长度为11.7～12.2μm.中肋骨条藻在各个季节均有发现,玛氏骨条藻仅出现在春季.

Influence of N, P, Fe Nutrients Availability on Nitrogen Metabolism-Relevant Genes Expression in Skeletonema marinoi

Nitrogen(N), Phosphorus(P), and Iron(Fe) are essential elements for cellular structure and metabolism. In addition to dissolved inorganic nitrogen(DIN), phytoplankton is able to utilize dissolved organic nitrogen(DON). There is general consensus that both bacteria and higher plants nitrogen metabolism is affected by phosphate availability; this was also found to be true in coccolithophorid. Iron affects the structure and function of ecosystems through its effects on nitrogen metabolism. However, it is unclear how these nutrients affect Skeletonema marinoi's nitrogen metabolism. Here, using RT-qPCR, we investigate effects of N, P, and Fe on S. marinoi's nitrogen metabolism and nitrate reductase activity. These results illuminate that in S. marinoi, various nutrients have direct regulation on these genes expression at the molecular level. The varying degree of responses for these genes expression with differing N sources may act to increase the efficiency of nutrient capture when nitrate is limited. Suitable gene expression occurs at a N/P ratio of 16, which represents the atomic N/P ratio of phytoplankton cells and N/P concentrations in ocean; thus, nitrogen metabolism gene expression should be regulated by the existing N/P ratios in the phytoplankton's internal and external environment. Fe concentration has a direct and significant effect on nitrogen metabolism by regulating gene expression and nitrate reductase activity. Gene expression profiles identified in S. marinoi provide a foundation for understanding molecular mechanisms behind diatom nitrogen metabolism with changing N, P, and Fe nutrients allowing a basic understanding of how diatom growth is affected by nutrient utilization.

Effects of different phosphorus concentrations and N/P ratios on the growth and photosynthetic characteristics of Skeletonema costatum and Prorocentrum donghaiense

The effects of different phosphorus(P) concentrations(0.36, 3.6, and 36 μmol/L corresponding to low-, middle-, and high-P concentration groups, respectively) and nitrogen(N)/P ratios on the growth and photosynthetic characteristics of S keletonema costatum and Prorocentrum donghaiense were studied. For both species, the high-P(HP) concentration group showed the greatest algal density and highest specifi c growth rate. Changes in the maximum effi ciency of photosystem Ⅱ(F _v/F_m) were monitored under the various P and N/P conditions. The largest decrease in F _v/F_m was in the low-P(LP) group in S. costatum and in the HP group in P. donghaiense. There were high rapid light curves and photochemical quantum yields(Φ _(PSⅡ)) for S. costatum in the HP group, while the actual photosynthetic capacity was higher in P. donghaiense than in S. costatum in the MP group. Under eutrophic but relatively P-restricted conditions, P. donghaiense had higher photosynthetic activity and potential, which could cause this dinofl agellate to increasingly dominate the phytoplankton community in these conditions. Under the same P concentration and N/P ratio, P. donghaiense had a larger relative maximum rate of electron transport and higher Φ _(PSⅡ) values than those of S. costatum. These differences between P. donghaiense and S. costatum may explain the interaction and succession patterns of these two species in the Changjiang(Yangtze) River estuary from a photosynthesis perspective.

Nutrient compositions of cultured Thalassiosira rotula and Skeletonema costatum from the Jiaozhou Bay in China

Carbon, nitrogen, phosphorus, silicon composition of cultured two different sized phytoplankton common species of Thalazsiosira rotula and Skeletonema costatum from the Jiaozhou Bay were measured. Carbon, nitrogen, phosphorus, silicon contents in cell were obvious higher in T. rotula than in S. costatum, but the percents of nitrogen, phosphorus, sihcon contents in cell dry mass in T. rotula were lower than those in S. costatum. The dry mass concentrations of nitrogen,phosphorus, silicon in S. costatum were much higher than those in T. rotula, particularly silicon, the former was 6. 4 times of the latter, showing that S. costatum could more assimilate these elements. Especially, S. costatum had competitive dominance for assimilating silicon, which is beneficial to its becoming a major dominant species in relative short silicon of the Jiaozhou Bay. There were some differences in numerical value of nutrient ratios both laboratory-cultured phytoplankton and different sized suspended particulates （ mainly phytoplankton） in the Jiaozhou Bay, which was caused by the changes of environment. High contents of carbon, nitrogon and relative low phosporus, sil- icon, high molar ratio of nitrogen to phosphorus （far higher than Redfield value） and low ratio of silicon to phosphorus and silicon to nitrogen （far lower than Redfield values） in the two diatoms and different sized suspended particulates were consistent with those in the seawater. Relative short silicon in the seawater and phytoplankton showed that silicon was possibly affectting phytoplankton growth in the Jiaozhou Bay.

Estimation of growth rate of Skeletonema costatum based on relative expression amount of PCNA gene

Partial sequence of Skeletonema costatum proliferating cell nuclear antigen （PCNA） gene was obtained by reverse transcriptase PCR（RT-PCR） and 3＇ rapid amplification of cDNA ends （3＇-RACE） techniques. Based on the obtained PCNA and cytochrome b gene（ Cyt b gene） sequences, a real-time fluorescent quantitative PCR （FQ-PCR） method was developed to detect the expression S. costatum PCNA gene, and this method was applied to study the relationship between the growth rate of S. costatum and the average expression amount of PCNA gene in a single cell. The expression amount of PCNA gene had large variation in cells collected at different culture phases, and the trend was well consistent with the growth rate, which suggested that the expression amount of PCNA gene correlated well with the cell division, and the PCNA could be a promising indicator for the S. costatum cell proliferation. Furthermore, using the PCNA gene as the objective gene and the Cyt b gene as the house-keeping gene, a new method for estimating the in situ growth rate of S. costatum was established by analysis of the relative expression quantity （REQ） of the PCNA gene.

Influences of external nutrient conditions on the transcript levels of a nitrate transporter gene in Skeletonema costatum

To verify the feasibility of high-affinity nitrate transporter gene （Nrt2） as an indicator of nitrogen status, changes in the transcript levels of transcripts associated with phosphate starvation and different nitrate concentrations were studied using real-time quantitative reverse-transcription PCR （QRT-PCR） technology in batch cultures of Skeletonema costatum. The results show that compared with P-replete condition, P starvation could reduce the Nrt2 transcript levels apparently. Nrt2 transcript levels had a significant negative linear correlation with nitrate concentrations below 40 pmol/L. The results of 48 h short-term incubation experiment under different nitrate concentrations confirmed this correlation, and the following regression equation is built： y = -3.305x ＋ 98.95, R2 = 0.988, where x represents nitrate concentrations （〈40 btmol/L） and y represents the Nrt2 transcript levels.

Study on the Effect of Monochromatic Light on the Growth of the Red Tide Diatom <i>Skeletonema Costatum</i>

Effects of light intensity and quality of three kinds of LED monochromatic lights (blue, green, and red) on the growth of Skeletonema costatum are investigated in batch culture conditions. Seven light intensities (20, 30, 40, 45, 50, 60 and 80 μmol·m-2·s-1) are used to evaluate the specific growth rate, spectrum absorption coefficient and saturated light intensity of LED monochromatic light. Results show that the growth rates of Skeletonema costatum increase with the enhanced light intensity;however, the light level beyond the saturation light intensity inhibited the growth of Skeletonema costatum. Compared with red and green light, the growth rate of Skeletonema costatum under blue light is higher within saturated light intensity, and saturated light intensity of LED monochromatic light is lower under blue light and higher under green light. It is concluded that under different monochromatic light, the saturated light intensity decreases and the growth rate increases with the increasing of spectrum absorption coefficient.

Effect of Temperature on the Release of Transparent Exopolymer Particles(TEP)and Aggregation by Marine Diatoms(Thalassiosira weissflogii and Skeletonema marinoi)

The presence of diatoms is accompanied by the production of a large amount of extracellular polymeric substances,which are mainly composed of carbohydrates.Transparent exopolymer particles(TEP)are a large class of extracellular polymeric substances with high stickiness that promotes the formation of aggregates and marine snow,which affects marine bio-carbon pump efficiency.The purpose of this research was to determine how temperature increases affect the allocation of cellular carbohydrates and the formation and aggregation of TEP.The results showed that the responses of two different diatom species(Thalassiosira weissflogii and Skeletonema marinoi)differed according to temperature.The cell density and chlorophyll a concentration of the former were not significantly correlated with temperature,while those of the latter were significantly decreased with increasing temperature.This indicates that the two species of diatom may have different heat tolerance ranges.A temperature increase will promote significant formation of TEP by both types of diatoms,including aggregation of S.marinoi as the temperature rises,meaning that the high temperature will produce an aggregate with a larger particle size and thus may increase the sedimentation rate of organic carbon.Moreover,the TEP aggregation of T.weissflogii did not increase;therefore,its particle size was smaller,and so it may remain on the sea surface at high temperatures for longer periods.These influences have a profound impact on the biogeochemical cycling of carbon.

河口浮游硅藻Skeletonema costatum光合作用动力学及生理生态学特性

在实验室中，模拟河口自然条件、培养浮游硅藻Ｓｋｅｌｅｔｏｎｅｍａｃｏｓｔａｔｕｍ、测定各种光合作用动力学、生理生态学特征参数。结果包括：光合作用与辐照关系、光合作用能力、光合作用最大放氧量、光能利用率、光需要量、闪光光合产量、光合作用单位大小、光反应最短反应转换时间值以及藻类细胞的捕光潜能等，分析了主要参数的意义。

Skeletonema cf.costatum Biogenic Silica Production Rate Determinated by PDMPO Method

Diatoms are the only ecological phytoplankton that require silicic acid for growth.They are also the dominant contributor of ocean's total primary productivity.Generation and circulation with silica walls,which the siliceous organisms form,is an important component of the marine biological pump.It is crucial to the study of the operational mechanisms of biological pump with different sea areas.Moreover,it is the key link to the study of global silicon cycle.This paper introduces the basic mechanism of the formation of diatom silica walls and a new way of researching silicic acid metabolism,namely the 2-(4-pyridyl)-5-((4-(2-dimethylaminoethylaminocarbamoyl)-methoxy)phenyl)oxazole(PDMPO) dyeing method.Under a fluorescence microscope after excitation with bright green fluorescence,it can combine with silicic acid to form a complex into the Si deposition within diatom cells.The advantage of this method is that it can monitor the metabolism of silicate after adding PDMPO.For experimentation and sample collection in each of the specified time points,samples were determinated through the unutilized silicic acid,silica dissoluble intracellular and Si deposition within diatom cells,not only using hot alkaline digestions method but also PDMPO dyeing method.Results showed a good linear relationship between PDMPO fluorescent value and biogenic silica concentration.It was also indicated that PDMPO had no deleterious impact on Skeletonema cf.costatum growth for 34 h and was useful for tracking newly-deposited biogenic silica in diatoms' frustules.

Isolation, characterization and implications of the bacterial communities associated with established cultures of Chattonella marina(Raphidophyceae) and Skeletonema costatum(Bacillariophyceae)

Cultivable bacteria coexisting in the cultures of two microalgal species, Chattonella marina(Raphidophyceae)and Skeletonema costatum(diatom, Bacillariophyceae), which have been maintained in the laboratory for several years, were examined in this study. Forty-eight and thirty-four cultivable bacterial strains were isolated from different growth stages of C. marina and S. costatum cultures, respectively. A total of twelve unique bacterial phylotypes were isolated. These bacterial phylotypes belonged to Alphaproteobacteria, Gammaproteobacteria,Bacteroidetes, and Actinobacteria. Alphaproteobacteria predominated in phycospheres of both microalgae, and Rhodobacteraceae was the most common family. Bacterial phylotypes were more diversified in cultures of S.costatum than in those of C. marina. Bacterial concentrations increased remarkably after the late stationary phase of C. marina, which might account for the decline in algal cells. One phylotype of S. costatum-associated bacteria had inhibitory effects on Chaetoceros curvisetus(Bacillariophyceae). However, most bacterial phylotypes from cultures of C. marina showed significant inhibition of the growth of C. curvisetus. The results suggested that bacteria associated with C. marina might have some ecological roles in its competition with diatoms.

Effects of iron on growth,degree of pigmentization and nitrogen assimilation in Skeletonema costatum

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The Effect of UV Light and CO₂in the Production of Polyunsaturated Aldehydes in <i>Skeletonema costatum</i>(Bacillariophycea)

Skeletonema costatum was submitted to two experiments using UV lights and CO2with the purpose of observing changes in the lipids profile and the synthesis of polyunsaturated aldehydes (PUA) after cell disruption. When cells receive CO2 supply, it was noticed that the production of PUA was significantly lower. The same was observed when the culture was treated with a dose of 45.9 kJ·m-2 of ultra-violet A/B ray. The premise to all experiments was the production of 2,4-heptadienal compared to the supply of EPA as substrate. As a result, the same synthesis rate was observed both when the CO2 treatment was applied and in the experiment control. On the other hand, the culture subjected to ultraviolet radiation showed a 68% greater demand with the utilization of the substrate. These observations suggested that EPA was consumed before cell disruption and was probably exuded to the surrounding environment as a sign of stress. Changes in cell morphology could be observed by the migration of the chloroplast nearby the cell wall, where PUA was produced, indicating a defense strategy.

纳米二氧化硅与汞(Hg^2＋)对中肋骨条藻(Skeletonema costatum)的联合毒性效应

随着纳米材料在日常生产生活中的广泛应用,部分纳米颗粒物不可避免地会通过废弃物排放等途径进入海洋.当纳米颗粒物与海洋中的污染物(如与重金属)共存时,因其独特的物化特性往往会成为污染物的良好载体并在生物体内累积,从而增加已有污染物和生物的相互作用,对海洋环境构成潜在的生态风险.已有的研究更多关注单一纳米材料的生态毒性效应,有关纳米颗粒物与污染物的复合生物效应的研究较少.因此,本文研究了已广泛应用的纳米Si O2与常见的重金属污染物Hg^(2+)对东海常见海洋微藻-中肋骨条藻(Skeletonema costatum)的联合毒性效应.结果表明,Hg^(2+)会抑制中肋骨条藻的生长,24 h-EC50、48 h-EC50和72 h-EC50值分别为56.3μg·L^(-1)、58.6μg·L^(-1)和36.8μg·L^(-1);低浓度的纳米Si O2(1 mg·L^(-1)和5 mg·L^(-1))未对中肋骨条藻的生长产生抑制作用,而较高浓度的纳米Si O2(≥10 mg·L^(-1))会显著(P<0.05)抑制中肋骨条藻的生长,并且提升微藻超氧化物歧化酶SOD的活性,影响微藻的抗氧化系统.添加1 mg·L^(-1)纳米Si O2会增强Hg^(2+)对中肋骨条藻的生长抑制作用,Hg^(2+)的24 h-EC50和48 h-EC50分别下降至41μg·L^(-1)和43μg·L^(-1),虽然1 mg·L^(-1)纳米Si O2本身没有对中肋骨条藻产生生长抑制作用,但是能够明显增强Hg^(2+)对中肋骨条藻的毒性.纳米Si O2对Hg^(2+)有着较强的吸附能力,在60 min时,100 mg·L^(-1)纳米Si O2对100μg·L^(-1)的Hg^(2+)的吸附率为90.08%,最大吸附量为5.92 mg·g^(-1).吸附了Hg^(2+)的纳米Si O2在中肋骨条藻内的累积可能是造成这种协同毒性的主要原因.