黄龙带水库甲藻水华的脂肪酸组成特征

浮游植物是水体颗粒物中最重要的组成,同时也是生态系统中物质和能量传递的重要物质基础。脂肪酸是浮游植物细胞内一种重要的生理构件,并具有重要和特殊的生理功能。由于不同浮游植物所含的颗粒脂肪酸不同,因此自然水体中的颗粒脂肪酸种类和数量的组成与变化反映了水体中浮游植物的群落结构及演替过程。在水体富营养化过程中,浮游植物的组成也随之变化,因此研究水体中颗粒脂肪酸的浓度和组成结构可以直接反映水体的富营养化水平和特征的生化指标,也能有利于掌握不同类型浮游植物水华的发生机制。2005年4月,在中国广东一座处于北回归线中营养型水平的水库-黄龙带水库中发生了二角多甲藻水华,本研究主要研究了此次水华过程中的浮游植物群落结构的变化、水体中颗粒物的脂肪酸组成和浓度的变化,探讨了热带亚热带地区二角多甲藻水华过程中浮游植物群落与脂肪酸组成特征、脂肪酸组成特征与水体营养状态之间的关系。结果表明:黄龙带水库为中富营养水平水库,此次共鉴定出藻类28种,二角多甲藻(Peridinium bipes Stein)是这次水华的优势种。其生物量变化为0～5138μg·L^-1。在水华高峰期二角多甲藻生物量占总生物量的80%以上,水华消退期占30%以下。硅藻生物量在水华高峰期有下降趋势,水华消失期有上升趋势;蓝藻的增长趋势更加明显,绿藻在整个过程中生物量较低,波动不大。水华过程中脂肪酸的种类丰富,浓度很高。共检测出脂肪酸21种,包括各种饱和脂肪酸(SFA),单不饱和脂肪酸(MUFA)和多不饱和脂肪酸(PUFA),含量变化为0～74.593μg·L^-1。在水华高峰期,偶碳数饱和脂肪酸占有非常明显的优势,而奇碳数脂肪酸相对浓度较少,总脂肪酸浓度为85.5～192.2μg·L^-1。与水华高峰期相比,水华消退期的总脂肪酸浓度仅有16.5～45.5μg·L^-1。水华消退期饱和脂肪酸的相对丰度要高于水华高峰期,而多不饱和脂肪酸的相对丰度则相反。C18:5和EPA、DHA等甲藻标志脂肪酸的检出频率和浓度较高,颗粒物脂肪酸特征较好地反映了甲藻水华过程浮游植物群落结构的变化;并为淡水甲藻脂肪酸的研究提供一些基础资料。     

营养盐加富和鱼类添加对浮游植物群落演替和多样性的影响

浮游植物是水体生态系统敞水区最重要的初级生产者,其组成与多样性反映了群落的结构类型和存在状态。通过围隔实验,模拟水库春季发生的营养盐加富和鱼类放养的干扰,分析在这两种干扰下的浮游植物群落演替过程中优势种和稀有种的变化,并通过以丰度与生物量为变量的香农和辛普森多样性指数的计算,分析浮游植物群落演替过程中的多样性变化特征。结果表明,营养盐加富干扰下的浮游植物群落的优势种变化和演替更为明显,营养盐加富与鱼类添加对浮游植物群落多样性变化的影响符合中度干扰理论。在优势种优势度变化较大的浮游植物群落演替过程中,多样性指数与浮游植物生物量有较高的负相关性。在浮游植物群落演替过程中,香农和辛普森多样性指数的变化趋势基本一致,采用丰度与生物量为变量的两种多样性指数的计算结果对实验系统中浮游植物群落多样性的分析结果没有明显的影响。     

短小芽孢杆菌溶藻效应研究

随着全球水体富营养化的加剧,有害藻类水华的暴发日趋频繁,其造成的环境和经济问题日益引起人们的重视,寻求有效的水华和赤潮防治途径势在必行。溶藻细菌作为水生生态系统中生物种群结构和功能的重要组成部分,对维持浮游植物生物量平衡具有非常重要的作用。不少研究认为水华和赤潮的突然消亡可能与溶藻细菌的感染有关。有些溶藻细菌能够分泌细胞外物质,对宿     

放养鲢鱼(Hypophthalmichys molitrix C et V)对水库围隔浮游生物群落的影响

本文研究在水库围隔实验生态系统中鲢鱼对浮游生物群落的影响。结果表明,放养鲢鱼后,浮游动物生物量、浮游植物生物量、叶绿素a和浮游植物毛产量分别下降了58.7％、63.6％、52.5％和65.0％;透明度、浮游植物群落多样性指数分别提高了18.2％、32.5％;铜绿微囊藻数量减少了90.6％“水华”得到明显抑制。但小型绿藻(<20μm)数量未出现显著变化,因而其在藻类生物量中所占比例反而提高了82.3％。围隔内可被鲢鱼滤食的大型藻类(硅藻、甲藻、隐藻和绿藻(>20μm))占藻类生物量的85.8％,因此鲢鱼的存在能明显限制浮游植物的生物量。此外,放养鲢鱼还显著降低了水体中的COD,TP,DO和pH值,这表明鲢鱼对水质有净化作用。     

三峡水库神农溪2014年春季浮游藻类演替成因分析

摘要：【目的】研究三峡水库神农溪库湾春季水华期间浮游藻类演替及其成因分析。【方法】2014年3–5月在神农溪库湾布置了6个断面(SN01–SN06),在神农溪汇入长江干流河口附近水域设置1个断面CJBD,对浮游藻类、相关环境因子及水动力因子进行了同步监测,据此分析了水体层化结构及水动力特性。【结果】神农溪在监测时段内共检测到浮游藻类6门38种(属);库湾浮游藻类生物量时间上差异显著(ANOVA,P<0.05)。春季浮游藻类群落结构具有明显的演替规律,3月份暴发大面积的硅藻水华（藻密度>100×105 cells/L),小环藻(Cyclotella spp.)为优势藻种;4月在SN02–SN06暴发以小球藻(Chlorella spp.)为主要优势种、衣藻(Chlamydomonas spp.)为次优势种的绿藻水华(藻密度>100×105 cells/L),5月份受水位大幅消落影响,浮游藻类生物量降低且无明显优势藻种。【结论】在具备充足的营养盐的水体中,水体层化结构与水动力特性对浮游藻类演替影响重大。三峡水库水位处于快速消落阶段时,流速成为抑制神农溪库湾藻类生长的主要因素。     

太湖湖岸带浮游植物初级生产力特征及影响因素

利用高频溶解氧监测,估算了太湖梅梁湾湖岸带浮游植物初级生产力的高频变化特征。结合同步气象监测及浮游植物、浮游动物和营养盐的周年逐周观测数据,分析了气象和环境条件对富营养化湖泊浮游植物初级生产力的影响。结果发现,高频溶解氧监测估算的初级生产力变化与浮游藻类生物量的变化一致,能够反映出浮游植物生产力的昼夜变化、季节变化等规律。统计分析表明,气温对太湖这一富营养化湖泊初级生产力影响很大;氮的供给与浮游动物的选择性牧食也是影响浮游植物初级生产力的重要因素。湖岸带的水华堆积过程对初级生产力影响巨大,气象、水文过程又加剧了蓝藻水华初级生产力的变化幅度,反映出富营养化湖泊初级生产力可能存在极大的时空不均一性。研究表明,溶解氧高频监测法估算初级生产力能够捕捉到湖泊初级生产力的快速变化过程,可以用于富营养化湖泊初级生产力监测、蓝藻水华灾害预警中。     

香溪河库湾浮游藻类种类演替及水华发生趋势分析

三峡水库一期工程蓄水前半年(2003年1月—2003年6月)和蓄水后(2003年7月—2004年12月)期间,香溪河库湾浮游藻类的种类演替和数量变化的调查结果。与蓄水前的数据相比,蓄水仅半年绿藻的种类数就明显增加,约相当于蓄水前的3倍;硅藻的种类数略有减少;其余各门藻类的种类数亦有轻度变化。整个调查期间,藻类细胞密度和生物量的最高峰值均出现在S6采样点,细胞密度达6.93×107cells/L(2004年6月),生物量达87.24mg/L(2004年3月),其余采样点基本显示由北向南依次递减的趋势。本文参考早期资料并比较不同类型水域中藻类的种类演替和垂直分布情况,对三峡湖北库区水域水华的发生趋势进行了分析,初步认为三峡干流江段形成藻类水华的几率较小;流动的支流水域,在阳光充足、水温逐渐升高的春季容易发生藻类水华;在较封闭的静水区则随时都有发生藻类水华的可能性。     

洱海蓝藻水华暴发期浮游植物群落变化及影响因素

对洱海水质和浮游植物进行了调查, 分析了洱海藻类水华暴发季节水质营养水平及浮游植物多样性, 并探讨了洱海浮游植物种群演替的环境机制. 研究结果表明, 洱海蓝藻水华在6-10月份大量暴发, 蓝藻数量高达107 cells/L, 水华种类为微囊藻(Microcystis)属的一些种, 微囊藻在6-10月份占绝对优势, 最高可达90%以上. 分析5-11月洱海营养水平, 其中7月营养水平最高, 浮游植物生物量10月份最大(以叶绿素a表示). 使用SPSS里的pearson分析了浮游植物和各理化因子的关系, 结果表明相对于其他浮游植物种类, 总磷(TP)对微囊藻的影响比较大.       

水生生物对微囊藻毒素去毒分子机理及调控因子研究

近年来,随着工农业的不断发展,排入水体的各种污染物不断增加,加速了淡水水域的富营养化进程,使得浮游藻类大量繁殖,有害藻类水华频繁发生,世界各地不断有藻类污染水体引起人畜患病甚至死亡的事件报道。在淡水藻类中,毒性最强、污染范围最广的为蓝藻门,[第一段]     

富营养水体生物修复中浮游植物的群落特征

通过对生物修复中富营养小水体浮游植物群落的分析,探讨了生物修复对浮游植物的影响以及浮游植物对环境因子改变的响应。生物修复实施后的浮游植物种类数比实施前多;浮游植物细胞数和生物量却有明显的下降;而对于Shannon Weaver多样性指数,实施后较实施前有明显的上升;生物修复过程中美丽胶网藻水华得到控制,优势种的指示性由中污变为寡污,优势度也由极度的高优势变为中低度优势,水体治理的前期阶段浮游植物群落的种类组成和结构有明显的改变;浮游植物种类数分别与正磷酸盐和氮磷比呈显著负、正相关,正磷酸盐的浓度与氮磷比的大小对水体浮游植物的种群结构变化具有重要影响。       

Harmful algal blooms and eutrophication: Examining linkages from selected coastal regions of the United States

Coastal waters of the United States (U.S.) are subject to many of the major harmful algal bloom (HAB) poisoning syndromes and impacts. These include paralytic shellfish poisoning (PSP), neurotoxic shellfish poisoning (NSP), amnesic shellfish poisoning (ASP), ciguatera fish poisoning (CFP) and various other HAB phenomena such as fish kills, loss of submerged vegetation, shellfish mortalities, and widespread marine mammal mortalities. Here, the occurrences of selected HABs in a selected set of regions are described in terms of their relationship to eutrophication, illustrating a range of responses. Evidence suggestive of changes in the frequency, extent or magnitude of HABs in these areas is explored in the context of the nutrient sources underlying those blooms, both natural and anthropogenic. In some regions of the U.S., the linkages between HABs and eutrophication are clear and well documented, whereas in others, information is limited, thereby highlighting important areas for further research.     

Molecular approaches to diagnosing nutritional physiology in harmful algae: Implications for studying the effects of eutrophication

Every year harmful algal blooms (HABs) cause serious impacts to local economies, coastal ecosystems, and human health on a global scale. It is well known that nutrient availability can influence important aspects of harmful algae biology and ecology, such as growth, toxin production, and life cycle stage, as well as bloom initiation, persistence and decline. Increases in the rate of supply of organic matter to ecosystems (eutrophication) carries many possible ramifications to coastal systems, including the potential for nutrient enrichment and the potential for stimulation of harmful algal blooms. Traditional studies on algal nutrition typically use either cultured isolates or community level assays, to examine nutrient uptake, nutrient preference, elemental composition, and other metrics of a species’ response to nutrients. In the last decade, technological advances have led to a great increase in the number of sequences available for critical harmful species. This, in turn, has led to new insights with regards to algal nutrition, and these advances highlight the promise of molecular technologies, and genomic approaches, to improving our understanding of algal nutrient acquisition and nutritional physiological ecology, in both cultures and field populations. With these developments increased monitoring of nutritional physiology in field populations of harmful algae will allow us to better discriminate how eutrophication impacts these groups.     

东海原甲藻与中肋骨条藻的种间竞争数值模拟

研究探讨了两个零维箱式模型在东海典型赤潮藻东海原甲藻和中肋骨条藻竞争与演替研究中的应用。模型在采用不同接种密度下的单种培养实验数据进行参数校正后,被用来模拟不同N/P条件下单种培养实验以及两藻种共培养竞争实验,并以实验数据对其结果进行了验证。模拟结果表明,在单种培养条件下,模型能够较好地重现两种藻在不同N/P环境中的生长及对营养盐的利用;共培养实验的模拟结果显示,在所有初始细胞密度比例条件下,中肋骨条藻的最终密度均会超过东海原甲藻,且PO4的消耗主要源于中肋骨条藻的利用,与实验结果一致,表明模型能够很好地体现两种藻的竞争结果及对营养盐的竞争关系;由于模型不足以模拟除营养盐竞争以外的藻间相互作用,模拟结果未体现东海原甲藻细胞数迅速衰减这一现象,有待进一步研究。     

Promotion of harmful algal blooms by zooplankton predatory activity

The relationship between algae and their zooplanktonic predators typically involves consumption of nutrients by algae, grazing of the algae by zooplankton which in turn enhances predator biomass, controls algal growth and regenerates nutrients. Eutrophication raises nutrient levels, but does not simply increase normal predator-prey activity; rather, harmful algal bloom (HAB) events develop often with serious ecological and aesthetic implications. Generally, HAB species are outwardly poor competitors for nutrients, while their development of grazing deterrents during nutrient stress ostensibly occurs too late, after the nutrients have largely been consumed already by fast-growing non-HAB species. A new mechanism is presented to explain HAB dynamics under these circumstances. Using a multi-nutrient predator-prey model, it is demonstrated that these blooms can develop through the self-propagating failure of normal predator-prey activity, resulting in the transfer of nutrients into HAB growth at the expense of competing algal species. Rate limitation of this transfer provides a continual level of nutrient stress that results in HAB species exhibiting grazing deterrents protecting them from top-down control. This process is self-stabilizing as long as nutrient demand exceeds supply, maintaining the unpalatable status of HABs; such events are most likely under eutrophic conditions with skewed nutrient ratios.     

Composition of inorganic and organic nutrient sources influences phytoplankton community structure in the New River Estuary, North Carolina

The New River Estuary, NC, is a nutrient-sensitive, eutrophic water body that is prone to harmful algal blooms. High annual loading from the watershed of varying nutrient forms, including inorganic phosphorus and inorganic and organic nitrogen, may be linked to the persistence of algal blooms in the estuary. In order to evaluate phytoplankton response to nutrient inputs, a series of in situ nutrient addition experiments were carried out during June 2010 to July 2011 on water from an estuarine site known to support algal blooms. Estuarine water was enriched with nutrients consisting of individual and combined sources of dissolved inorganic nitrogen, orthophosphate, urea, and a natural dissolved organic nitrogen (DON) addition derived from upstream New River water. The combined inorganic N and P addition most frequently stimulated phytoplankton biomass production as total chlorophyll a. The responses of diagnostic (of major algal groups) photopigments were also evaluated. Significant increases in peridinin (dinoflagellates), chlorophyll b (chlorophytes), and myxoxanthophyll (cyanobacteria) were most frequently promoted by additions containing riverine DON. Significant increases in zeaxanthin (cyanobacteria) were more frequently promoted by inorganic nitrogen additions, while increases in fucoxanthin (diatoms) and alloxanthin (cryptophytes) were not promoted consistently by any one nutrient treatment. Evaluating the impact of varying nutrient forms on phytoplankton community dynamics is necessary in order to develop strategies to avoid long-term changes in community structure and larger-scale changes in ecosystem condition.     

Harmful algal blooms: combining excitability and competition

Harmful algal blooms (HABs) characterized by a large concentration of toxic species appear rather rarely, but have a severe impact on the whole ecosystem. To study on possible trigger mechanisms for the emergence of HABs, we consider a nutrient-phytoplankton-zooplankton model to find the conditions under which a toxic phytoplankton species is able to form a bloom by winning the competition against its nontoxic competitor. The basic mechanism is related to the excitability of the system, i.e., the ability to develop a large response on certain perturbations. In a large class of models, a HAB results from a combined effect of nutrient enrichment and selective predation on different phytoplankton populations by zooplankton. We show that the severity of HAB is controlled by nutrient enrichment and zooplankton abundance, while the frequency of its occurrence depends on the strength of selectivity of predation. Thereby the intricate interplay between excitability, competition, and selective grazing pressure builds the backbone of the mechanism of the emergence of HABs.     

Lagoonal stormwater detention ponds as promoters of harmful algal blooms and eutrophication along the South Carolina coast

In the rapidly urbanizing coastal zone of South Carolina, intensive landscape maintenance and turf management are significant sources of nonpoint source pollutant loadings. The best management practice of choice for stormwater in this region is wet detention ponds, the majority of which are brackish lagoons. Typically, stormwater is piped directly into the ponds, but ponds have limited capacity for processing pollutants. These eutrophic brackish ponds are “hot spots” for harmful algal blooms (HABs)—over 200 blooms from 23 different species were documented over the last 4 years, many associated with measured toxins, fish kills or shellfish health problems. Because these ponds exchange with tidal creeks, they are potential sources for HAB dispersion into adjacent estuaries. Also, flux measurements indicated that groundwater was both a source of nutrients to the ponds and a mechanism for transporting nutrients from the ponds. These findings suggest that manmade ponds as presently designed along the SC coast may contribute to estuarine eutrophication and HAB prevalence. A summary of HAB occurrences in SC lagoonal ponds from 2001 to 2005 is presented, and a project is described that simulates the effectiveness of constructed wetlands as a supplementary best management practice designed to process stormwater and groundwater and remove nutrients prior to entering wet detention ponds.     

The Diversity of Harmful Algal Bloom-Triggering Mechanisms and the Complexity of Bloom Initiation

Mechanisms influencing initiation of harmful algal blooms (HABs) are diverse, and are not likely to be mutually exclusive. Rather, initiation of HABs is a result of interactions between processes, which result in biological, physical, and chemical conditions optimal for a bloom. Due to the complexity of some bloom initiation processes, bloom-preventative management may be possible. Results from a modeling exercise and a laboratory experiment indicated that a phytoplankton bloom could be circumvented through manipulation of the nutrient-loading mode, i.e., pulsed vs. continuous loading. These findings, should they prove consistent in more robust field experiments, may provide insights for the development of new management approaches for some HABs. Optimal bloom conditions, however, vary between HAB species. Consequently, it is unlikely that a single management solution will exist. Preventative management efforts will require early warning of HAB initiation, perhaps even before the appearance of an HAB species. An indicator based on the dynamic nature of phytoplankton succession events and phytoplankton species diversity may prove useful for this purpose. Applying this index to an existing plankton data set showed that Microcystis blooms might have been predicted months before the start of the bloom.     

CULTIVATION STUDIES OF GIGARTINA SKOTTSBERGII IN SOUTHERN CHILE

Increases in population and agriculture in coastal areas can result in increased nutrient inputs and alterations in the ratios of organic to inorganic nutrients in coastal waters. Such changes in coastal nutrient regimes can affect phytoplankton community structure by creating conditions favorable for growth and dominance of algae that were not dominant before. The effect that changes in ratios and concentrations of nutrients have on toxicity of harmful algal species is not well known. There seems to be a relationship; however, between nutrient stress and toxin production among harmful phytoplankton producing low-N toxins, e.g. Diarrhetic Shellfish Poisoning (DSP) toxins. Even less is known about the relationship between organic nutrient uptake and toxin production. Benthic species and species in coastal areas are probably exposed to greater fluxes of dissolved organic nitrogen (DON). In this study, benthic and planktonic species of Prorocentrum were grown on L1 media with the sole N-source varying among treatments as nitrate, ammonium, urea, L-glutamic acid, and high molecular weight natural DON. An ELISA specific to the DSP toxins, okadaic acid and 35-methylokadaic acid, was used to determine toxin production by each species when grown on the different N sources. Preliminary results indicate that some organic forms of N support growth as well as inorganic forms for Prorocentrum minimum , P. mexicanum , and P. hoffmannianum.     

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.