东海原甲藻对羊栖菜合子生长及光合活性的化感作用研究

为评估东海原甲藻(Prorocentrum donghaiense)赤潮发生对羊栖菜(Sargassum fusiformis)幼苗产量的影响并探讨其化感机理,在实验室条件下分别利用浓度为1.00×10⁵cells/mL东海原甲藻活细胞悬浮液(LC)、细胞破碎液(RC)和无细胞滤液(FC)培养羊栖菜合子,并对其生长发育及光合活性进行测定。结果显示,LC、RC和FC均会抑制羊栖菜合子的生长、叶绿素a合成和光合活性,其中FC及LC对合子的抑制程度相似且均大于RC。JIP-test分析表明,FC及LC对合子的最大量子产率(φP_o)、性能指数(PI)及PSⅡ反应中心密度(RCs/ABS)的抑制作用显著大于RC。表明东海原甲藻主要通过向细胞外释放化感物质产生抑制作用,这些化感物质抑制了羊栖菜合子PSⅡ的电子传递,使PSⅡ部分光化学反应中心(RCs)失活,进而使大量激发能转化为热能被耗散掉。而RC中可能含有某些能够刺激羊栖菜合子生长的物质,从而在一定程度上抵消了化感物质的抑制作用。结果表明东海原甲藻对羊栖菜合子的抑制作用主要是由化感物质引起的,东海原甲藻赤潮可以抑制羊栖菜合子的发育和光合活性,减少羊栖菜种苗产量,并最终阻碍了羊栖菜产业的发展。     

营养盐限制条件下塔玛亚历山大藻对东海原甲藻的化感作用研究

为明确塔玛亚历山大藻(Alexandrium tamarense)对东海原甲藻(Prorocentrum donghaiense)生长的化感作用,研究了在N、P限制及正常营养盐条件下(又称富营养)塔玛亚历山大藻无细胞滤液对东海原甲藻生长的影响,并探讨了3种不同营养盐条件下两种藻共培养时的生长状况。结果表明,半连续培养时,营养盐限制下,塔玛亚历山大藻无细胞滤液对东海原甲藻的生长均有一定影响。N限制下,5 d后东海原甲藻藻密度显著低于未加滤液的对照组,藻密度为1.02×107 cells L-1,对照组为1.7×107 cells L-1;P限制下,东海原甲藻藻密度与对照组差异不显著,5 d后藻密度为1.44×107 cells L-1;富营养条件下,东海原甲藻藻密度与对照组无明显区别。共培养时,塔玛亚历山大藻对东海原甲藻生长的抑制作用更为显著,N、P限制下,4 d后东海原甲藻全部死亡,且聚集成团形成沉淀;富营养条件下,仍有少量东海原甲藻存活(藻密度3.3×104 cells L-1)。这表明,塔玛亚历山大藻对东海原甲藻的生长有一定的化感作用。营养盐限制可促进塔玛亚历山大藻化感物质的合成和释放,化感作用是塔玛亚历山大藻抑制东海原甲藻生长的原因之一。     

凤眼莲浸出液对东海原甲藻生长的抑制作用

研究了凤眼莲浸出液对赤潮藻东海原甲藻生长的影响。浸出液浓度以单位体积溶液中所含凤眼莲鲜重表示。结果显示,在浸出液浓度大于2g·L^-1时,活体凤眼莲浸出液和干凤眼莲浸出液对东海原甲藻的生长都有明显的抑制作用。在浸出液浓度达到8g·L^-1时,活体凤眼莲浸出液和干凤眼莲浸出液对东海原甲藻都具有杀灭作用,东海原甲藻全部死亡出现的时间分别为培养后的第4t和第5t。经121℃高温处理20min后的活体凤眼莲浸出液对东海原甲藻的抑制作用仍然存在,抑制作用并没有显著减弱。研究结果表明凤眼莲的抑藻物质具有用来控制赤潮生物东海原甲藻的潜在价值。     

米氏凯伦藻与东海原甲藻共培养条件下的种群竞争

米氏凯伦藻(Karenia mikimotoi)与东海原甲藻(Prorocentrum donghaiense)为有害赤潮生物,两者经常形成复合型赤潮.该文设置东海原甲藻的起始密度为400 cells·mL-1,米氏凯伦藻分别为200 cells·mL-1、400 cells·mL-1和800 cells·mL-1,通过共培养实验,初步研究米氏凯伦藻和东海原甲藻的种间关系.结果表明:共培养条件下,受到东海原甲藻的影响,米氏凯伦藻的生长受到抑制.米氏凯伦藻不同的起始密度对东海原甲藻的生长有不同的影响,较低的起始密度(200 cells·mL-1、400cells·mL-1)促进东海原甲藻的生长,使其增长率提高,生长曲线达到拐点的时间提前;高的起始密度(800 cells·mL-1)对东海原甲藻的生长有一定的抑制作用,使其增长率降低,生长曲线达到拐点的时间推迟.     

大型海藻分泌物亚麻酸对东海原甲藻的化感效应

东海原甲藻是常见有毒有害赤潮藻。本文从种群生长、光合效率和抗氧化系统等角度研究大型海藻分泌物亚麻酸胁迫下东海原甲藻的生理生化响应。结果表明:低浓度亚麻酸(200μg·L~(-1))对东海原甲藻的生长具有促进作用,200~1000μg·L~(-1)浓度下,东海原甲藻的生长受到显著抑制,当亚麻酸浓度为1000μg·L~(-1)时,抑藻率达90%;200~1000μg·L~(-1)亚麻酸胁迫下,藻细胞光合色素含量显著降低,最大光能转化效率Fv/Fm降低,当亚麻酸浓度为1000μg·L~(-1)时,F_v/F_m为对照组的33.87%;随着亚麻酸浓度的增大,抗氧化酶活性(过氧化氢酶CAT、超氧化物歧化酶SOD和谷胱甘肽过氧化物酶GPx)与抗氧化非酶物质(还原型谷胱甘肽GSH、氧化型谷胱甘肽GSSG、抗坏血酸As A和脱氢抗坏血酸DHA)含量呈现出先升高后降低趋势;亚麻酸胁迫下丙二醛含量显著升高,表明膜脂过氧化程度加剧。以上结果说明,低浓度亚麻酸对东海原甲藻的生长具有促进作用,高浓度亚麻酸主要通过降低光合效率和细胞过氧化损害抑制东海原甲藻的生长。研究结果为生物法防控以东海原甲藻为优势藻种的赤潮提供了理论基础。     

东海原甲藻(Prorocentrum donghaiense)和链状亚历山大藻(Alexandrium catenella)对模拟食物链物质传递的影响

研究了东海原甲藻的基本营养组成,并就赤潮密度下的东海原甲藻(Prorocentrum donghaiense)和链状亚历山大藻(Alexandrium catenella)在单一和混合情况下对赤潮藻→卤虫模拟食物链物质传递的影响进行了探讨。结果表明:与其它饵料微藻相比,东海原甲藻必需氨基酸中的苯丙氨酸、赖氨酸和组氨酸含量明显偏低。东海原甲藻单独投喂时,卤虫对其的总物质转化效率随着藻密度的增加呈现先逐渐增加再逐渐降低的趋势。而当不同密度的东海原甲藻分别与一种硅藻小新月菱形藻(Nitzschia closterium)混合投喂时,随东海原甲藻密度的增加,卤虫选择性地增加对东海原甲藻的摄食,而降低对小新月菱形藻的摄食,并且其总物质转化效率逐渐降低。暴露于链状亚历山大藻藻液,卤虫体重减轻,且在其体内未检测到叶绿素a,表明卤虫未摄食该藻。当链状亚历山大藻藻细胞重悬液和去藻过滤液分别与小新月菱形藻或东海原甲藻混合时,卤虫对后两株藻的摄食量和总物质转化效率均有所降低。因此,在大规模赤潮发生时,东海原甲藻和链状亚历山大藻可能分别对浮游动物的营养和存活带来不利影响,并影响物质沿食物链的传递。     

我国东海赤潮原甲藻应属哪种？

阐述并讨论了中国东海长江口外经常发生的原甲藻赤潮原因种的种类认知问题．论述了自从Stein提出具齿原甲藻(Prorocendrum dentatum Stein)新种后迄今中外专家报告该种的描述及分布,并对比了具齿原甲藻与长江口的原甲藻的异同．研究证实我国东海的原甲藻与具齿原甲藻有较大的差别,主要表现在体积大小、藻体末端形态以及藻体前端突起的大小和形态等方面．本文汇集了国内外对具齿原甲藻与我国原甲藻的研究成果,对比认为。我国长江口外经常发生赤潮的原甲藻为东海原甲藻(Prorocendrum donghaiense Lu)．文中还讨论了由陆斗定发表的东海原甲藻需要补充修正的观点．在过去的数年中,我国东海长江口海域频繁爆发大面积的原甲藻赤潮,但对于赤潮原因种原甲藻(Prorocentrum)的定种问题存在两种不同的观点,一种观点认为本种是具齿原甲藻,另一种观点认为是东海原甲藻．为了阐明此种原甲藻的命名问题,于2002年11月在深圳召开了题为“我国东海赤潮原因种原甲藻分类学国际研讨会”．认为是P．dentatum的依据是长期以来国际上通常把类似我国东海的原甲藻定为P．dentatum,其根据是它的前端有突起等．而持不同观点的专家认为我国东海的这种原甲藻在细胞长度上与Stein描述的原P．dentatum差异很大,并且除少数样品末端尖伸外,大多数细胞末端是钝圆的．专家们还认为在日本、韩国等亚洲海域分布的被报告为P．dentatum的原甲藻与我国东海的此种原甲藻为同一种．综观各种观点,作者认为东海本种原甲藻应为东海原甲藻.     

东海具齿原甲藻的扫描电子显微结构

在光学显微镜分析鉴定的基础上,通过高分辨率的扫描电子显微镜,对东海赤潮原甲藻标本和美国国家海洋藻种中心(CCMP)的具齿原甲藻(Prorocentrum dentatum)藻株(CCMPl517)的细胞表面结构进行观察和比较,认为两者为同一种类．在分析大量文献资料的基础上,可以认为发生在我国东海水域的赤潮原甲藻种类是具齿原甲藻(Prorocentrum dentatum),而非新种．     

东海原甲藻（Prorocentrum donghaiense）和链状亚历山大藻（Alexandrium catenella）对模拟食物链物质传递的影响

研究了东海原甲藻的基本营养组成,并就赤潮密度下的东海原甲藻（Prorocentrum donghaiense）和链状亚历山大藻（Alexandrium catenella）在单一和混合情况下对赤潮藻→卤虫模拟食物链物质传递的影响进行了探讨。结果表明：与其它饵料微藻相比,东海原甲藻必需氨基酸中的苯丙氨酸、赖氨酸和组氨酸含量明显偏低。东海原甲藻单独投喂时,卤虫对其的总物质转化效率随着藻密度的增加呈现先逐渐增加再逐渐降低的趋势。而当不同密度的东海原甲藻分别与一种硅藻小新月菱形藻(Nitzschia closterium)混合投喂时,随东海原甲藻密度的增加,卤虫选择性地增加对东海原甲藻的摄食,而降低对小新月菱形藻的摄食,并且其总物质转化效率逐渐降低。暴露于链状亚历山大藻藻液,卤虫体重减轻,且在其体内未检测到叶绿素a,表明卤虫未摄食该藻。当链状亚历山大藻藻细胞重悬液和去藻过滤液分别与小新月菱形藻或东海原甲藻混合时,卤虫对后两株藻的摄食量和总物质转化效率均有所降低。因此,在大规模赤潮发生时,东海原甲藻和链状亚历山大藻可能分别对浮游动物的营养和存活带来不利影响,并影响物质沿食物链的传递。     

东海原甲藻修订及与相关原甲藻的分类学比较

分析了东海原甲藻(Prorocentrum donghaiense Lu)显微结构,并与具齿原甲藻(Prorocentrum dentatum Stein)模式种和Schiller的钝头原甲藻的描述等进行了比较,结果表明,它们之间的形态结构和个体大小具有很大的差别,这些差异远超出了同种个体因环境不同所造成的形态变化范围．从细胞形态及其表面结构可以判断,日本、韩国海区所记录并报道的“P．dentatum”与我国东海的东海原甲藻应属同一种．因此可以认为,我国东海赤潮高发区以及在韩国、日本海区的出现的高生物量(high biomass bloom—forming species)赤潮原甲藻不是Stein所发表的具齿原甲藻。而是东海原甲藻,并对其进行了进一步修订,其种名应为东海原甲藻Prorocentrum donghaiense Lu．     

Detection of bloom-forming dinoflagellates Karenia mikimotoi and Prorocentrum donghaiense using qPCR assays

Journal of Applied Phycology - The dinoflagellates Karenia mikimotoi and Prorocentrum donghaiense are both important causative species of harmful algal blooms (HABs) in the East China Sea. The...     

Effects of Two Potential Allelochemicals on the Photosystem II of <i>Nitzschia closterium</i> and<i> Monostroma nitidum</i>

In aquaculture, high-density seaweed farming brings higher economic benefits but also increases outbreaks of diatom felt. The effective control of diatom felt in high-density seaweed farming has always been a research hotspot. This study selected two potential allelochemicals 2-hydroxycinnamic acid and quinic acid to explore their effects on a diatom Nitzschia closterium and an economic seaweed Monostroma nitidum. The results showed that 2-hydroxycinnamic acid had better inhibitory effects than quinic acid on the growth, pigment content and photosynthetic efficiency of N. closterium. Their half-maximal inhibitory concentrations at 120 h (IC_{50–120 h}) were 0.9000 and 1.278 mM, respectively. Additionally, these allelochemicals had limited inhibitory effects on the growth, pigment content and photosynthetic efficiency of M. nitidum before 24 h. To further explore the allelopathic effect of these chemicals, this study focused on the photosystem II energy fluxes of N. closterium. It was found that 3 mM 2-hydroxycinnamic acid could destroy the whole photosynthetic system by devastating the PSII reaction centre (RC) before 24 h; however, the same concentration of quinic acid could only down-regulate the electron transport efficiency by changing the effective antenna size of an active RC and downregulating the PSII reaction centre density. These experimental results are expected to provide a new strategy to control diatom felt blooms on the high-density seaweed farming areas.     

东海原甲藻与中肋骨条藻的种间竞争特征

对东海原甲藻和中肋骨条藻按照起始Chl-a比1∶5、1∶1和5∶1进行了f/2条件下的共培养实验,以探讨这两种藻的种间竞争特征。实验结果表明在共培养体系中,中肋骨条藻完全占优势,而东海原甲藻的生长受到明显的抑制。应用Lotka-Volterra种间竞争模型对共培养实验进行模拟的结果表明,东海原甲藻与中肋骨条藻的种间竞争结果与初始密度配比无关,中肋骨条藻总会竞争胜过东海原甲藻。为了探讨他感作用对东海原甲藻和中肋骨条藻种间竞争的影响,采用了中肋骨条藻的无藻细胞滤液来进行培养实验。实验结果显示,中肋骨条藻滤液对东海原甲藻及其本身的生长均无明显影响,这表明他感作用并非中肋骨条藻获得优势的主要竞争方式。     

Occurrences of harmful algal blooms (HABs) associated with ocean environments in the South China Sea

Harmful algal blooms (HABs) occur frequently in the South China Sea (SCS), causing enormous economic losses in aquaculture. We analyzed historical HAB records during the period from 1980 to 2003 in SCS. We found that HABs-affected areas have expanded and the frequency of HABs varied during this period. The seasonal and annual variations, as well as causative algal species of HABs are different among the four regions. Areas with frequent HABs include the Pearl River Estuary (China), the Manila Bay (the Philippines), the Masinloc Bay (the Philippines), and the western coast of Sabah (Malaysia). HABs occurred frequently during March–May in the northern region of SCS, May–July in the eastern region, July in the western region, and year-round in the southern region. Among the species that cause HABs, Noctiluca scintillans dominated in the northern region, and Pyrodinium bahamense in the southern and eastern regions. Causative species also varied in different years for the entire SCS. Both P. bahamense and N. scintillans were the dominant species during 1980–2003. Some species not previously recorded formed blooms during 1991–2003, including Phaeocystis globosa, Scrippsiella trochoidea, Heterosigma akashiwo, and Mesodinium rubrum. Variations in HABs are related to various regional conditions, such as a reversed monsoon wind in the entire SCS, river discharges in the northern area, upwelling in Vietnam coastal waters during southwest winds and near Malaysia coastal waters during northeast winds, and eutrophication from coastal aquaculture in the Pearl River estuary, Manila Bay, and Masinloc Bay. Handling editor: D. Hamilton     

大型海藻裂片石莼藻粉对赤潮异弯藻光合作用抑制的研究

为了探究大型海藻裂片石莼(Ulva fasciata)防治赤潮的可行性,研究将赤潮异弯藻(Heterosigma aka-shiwo)分别暴露在浓度为0.6、1.2、2.4和4.8 g/L的裂片石莼藻粉中,观察赤潮异弯藻光合系统的响应.实验用植物效率分析法测定了赤潮异弯藻的光合效率,用透射电子显微镜法观察了赤潮异弯藻叶...     

绿藻栅藻对微囊藻的抑制效应及评价

为筛选具有控制微囊藻水华潜力的绿藻, 研究基于藻类之间的化感作用, 对34株绿藻开展筛选及评价工作。结果发现, 栅藻FACHB-1229的抑制率最高, 其滤液对微囊藻FACHB-3550和FACHB-905的抑制率分别为53.95%和48.39%; 通过对滤液中的物质进行GC-MS检测, 推测该藻株的效应物质可能为邻苯二甲酸二(2-甲氧基乙基)酯。进一步对FACHB-1229生长和光合放氧、氨氮耐受等指标进行评价, 结果发现: 该藻株在孔板中的生长速率(0.38±0.06)/d高于微囊藻生长速率(0.13±0.03)/d; 栅藻FACHB-1229的光合放氧速率高于同期测定的其他绿藻光合放氧速率, 可达(229.91±10.49) μmol O₂/(mg Chl.a·h); 同时该藻株对氨氮的耐受能力最强, 在氨氮浓度为1888.60 mg/L时其生长速率可达(0.30±0.08)/d。此外, 在与微囊藻FACHB-3550进行共培养时, 栅藻FACHB-1229所占比例持续升高。综上, 栅藻FACHB-1229具备与微囊藻竞争的优势, 有望成为微囊藻水华生物控制的优选材料。     

浮游植物的化感作用

生物化感作用研究是近年来兴起的交叉学科,是化学生态学研究的重要领域。研究水域浮游植物化感作用对了解浮游植物之间、浮游植物与其他生物之间的相互作用及作用机理具有重要意义,对了解赤潮和水华的发生机制及其生态控制等具有非常重要的作用。综述了海洋和湖泊浮游植物化感作用和化感物质的内涵,讨论了水体浮游植物化感作用的特点、研究化感作用的基本方法、化感物质的种类以及影响化感物质作用的生物和非生物因素,详细介绍了浮游植物化感物质的作用机理以及逃避和拈抗化感作用的方式,同时对目前研究的热点问题及未来研究的方向做了简要概述。     

沿岸海域富营养化与赤潮发生的关系

综述了赤潮的发生与沿岸海域富营养化的关系。近几十年来,人类活动使得天然水体的富营养化进程大大加速。营养负荷的增加与高生物量水华的增多相联系。控制营养输入后,浮游植物生物量或有害藻类水华事件也相应减少。营养的组成与浮游植物的种类组成及水华的形成有密切联系。有机营养对有害藻类水华的促进作用受到关注。营养输入时机影响浮游植物种间竞争的结果,因而对浮游植物的群落演替具有深远影响。由于浮游植物存在生理差异,因而对营养加富的反应因种而异。营养在调控某些有毒藻类的毒素产量方面也发挥着重要作用。此外,营养输入与藻类水华之间存在复杂的间接联系。当然,营养状况并非浮游植物群落演替的唯一决定因素。研究结果提示,控制营养输入、减缓水域富营养化是减少有害藻类水华发生的有效途径,而深入研究典型有害藻类的营养生理对策则为防治并最终消除有害藻类水华提供了理论基础。     

Development of a PNA probe for fluorescence in situ hybridization detection of Prorocentrum donghaiense

Prorocentrum donghaiense is a common but dominant harmful algal bloom (HAB) species, which is widely distributed along the China Sea coast. Development of methods for rapid and precise identification and quantification is prerequisite for early-stage warning and monitoring of blooms due to P. donghaiense. In this study, sequences representing the partial large subunit rDNA (D1-D2), small subunit rDNA and internal transcribed spacer region (ITS-1, 5.8S rDNA and ITS-2) of P. donghaiense were firstly obtained, and then seven candidate DNA probes were designed for performing fluorescence in situ hybridization (FISH) tests on P. donghaiense. Based on the fluorescent intensity of P. donghaiense cells labeled by the DNA probes, the probe DP0443A displayed the best hybridization performance. Therefore, a PNA probe (PP0443A) analogous to DP0443A was used in the further study. The cells labeled with the PNA probe displayed more intensive green fluorescence than that labeled with its DNA analog. The PNA probe was used to hybridize with thirteen microalgae belonging to five families, i.e., Dinophyceae, Prymnesiophyceae, Raphidophyceae, Chlorophyceae and Bacillariophyceae, and showed no visible cross-reaction. Finally, FISH with the probes PP0443A and DP0443A and light microscopy (LM) analysis aiming at enumerating P. donghaiense cells were performed on the field samples. Statistical comparisons of the cell densities (cells/L) of P. donghaiense in the natural samples determined by FISH and LM were performed using one-way ANOVA and Duncan's multiple comparisons of the means. The P. donghaiense cell densities determined by LM and the PNA probe are remarkably higher than (p<0.05) that determined by the DNA probe, while no significant difference is observed between LM and the PNA probe. All results suggest that the PNA probe is more sensitive that its DNA analog, and therefore is promising for the monitoring of harmful algal blooms of P. donghaiense in the future.