九龙江河口浮游植物的时空变动及主要影响因素

于2009年春（5月）、夏（8月）、秋（11月）在九龙江河口水域进行了水文、化学和生物的生态完全示范区综合外业调查,研究了九龙江河口浮游植物的种类组成、密度分布、季节变化、空间差异及主要影响因素,并结合前期资料分析了年际变动。结果表明,九龙江河口的浮游植物共记录7个门类75属134种。主体是硅藻,绿藻次之,甲藻和蓝藻较少,黄藻检出率高,裸藻和金藻零星检出。种类组成的空间差异大,绿藻在河口内区淡水水域比硅藻更占优势, 中肋骨条藻（Skeletonema costatum）、短角弯角藻（Eucampia zodiacus）、圆筛藻（Coscinodiscus spp.）、颗粒直链藻（Melosira granulata）、微小小环藻（Cyclotella. caspia）是河口区咸淡水水域及近海区的主要种类。浮球藻（Planktosphneria gelotinosa）、栅藻（Scenedesmus spp.）、盘星藻（Pediastrim spp.）、小席藻（Phormidium tenus）是河口内区淡水水域的主要种类。根据浮游植物的生态类型及其生境特征大致可分为三大类群。浮游植物密度夏季最高,平均为358.68103cells/L,密集中心的季节变化明显,密度分布由优势类群的密度分布决定。中肋骨条藻和短角弯角藻的数量庞大,导致优势种突出,多样性降低,种间分布不均匀,群落结构简单化。与史料比对,种类组成因淡水藻类的列入而更丰富,密度年际降低,中肋骨条藻仍是第一优势种,但优势度有较大降幅,优势类群有重大年际变化,细胞个体较小的种类占优。盐度和营养盐对浮游植物的分布及密度变化造成极大的时空差异,存在线性、复合线性、多项回归等复杂的相关关系。     

The plankton ecology of Lake St. Clair, 1984

Lake St. Clair phytoplankton and zooplankton abundance and composition was analyzed during the period of May to September 1984. In addition, size-fractionated primary productivity and other limnological parameters were measured. Highest phytoplankton biomass was observed during spring (May) with high values for the southern and southeastern regions of the lake. Seasonally, the mean phytoplankton biomass ranged between 0.17 and 1.18 g m^-3 with high values recorded during spring (May, June) compared to summer. In the spring the phytoplankton was dominated by Diatomeae followed by Chrysophyceae and Cryptophyceae. During the summer the diatoms showed a decreasing trend due to the relative prevalence of Chrysophyceae, Cryptophyceae, and Chlorophyta. The species composition was oligotrophic-mesotrophic with mixed occurrence of some eutrophic species. The phytoplankton size composition indicated dominance of microplankton/netplankton (> 20 µm) and ultraplankton (< 20 µm) during spring and summer respectively. On an overall basis ultraplankton contributed overwhelmingly to primary productivity, as much as 75 percent in the summer.The mean zooplankton biomass ranged from 173.0 to 1306.0 mg l^- dominated by Cladocerans (bosminids) in contrast to the other Great Lakes. Statistical evaluation of the phytoplankton — nutrient-contaminant interactions revealed positive correlations with heavy metals, suggestive of a physiological adaptation to contamination from the chemical valley. Based on low biomass, high Production/Biomass ratio, dominance of ultraplankton, characteristic species composition and plankton spectra, the lake appears to be an oligotrophic-mesotrophic perturbed ecosystem.     

Phytoplankton uptake of ammonium, nitrate and urea in the Neuse River Estuary, NC, USA

Uptake rates of ammonium, nitrate and urea were measured during the spring, summer and autumn (2001) in the eutrophic, nitrogen (N) limited Neuse River Estuary (NRE), North Carolina, USA. Ammonium was the dominant form of N taken up during the study, contributing approximately half of the total measured N uptake throughout the estuary. Nitrate uptake declined significantly with distance downstream comprising 33% of the total uptake in the upper estuary but only 11 and 16% in the middle and lower estuary, respectively. Urea uptake contributed least to the total pool in the upper estuary (16%), but increased in importance in the middle and lower estuary, comprising 45 and 37% of the total N taken up, respectively. The importance of regenerated N for fuelling phytoplankton productivity in the mesohaline sections of the NRE is demonstrated. The contribution of urea to the regenerated N pool suggests that internal regeneration of dissolved organic N may support a large proportion of the phytoplankton primary production and biomass accumulation in the middle and lower NRE. These results suggest that N-budgets based on dissolved inorganic N uptake rates alone will seriously under estimate phytoplankton N uptake.     

Effect of pollution on phytoplankton in the Ashar Canal,a highly polluted canal of the Shatt al-Arab Estuary at Basrah,Iraq

The effect of pollution on the phytoplankton in the Ashar Canal was studied during March and June 1976. Higher temperatures were recorded in June. The canal water was more turbid than that of the adjoining Shatt al-Arab estuary due to high algal populations and sewage disposal. The chlorosity values were remarkably high in the canal, due to sewage disposal. The flood waters in June lowered the chlorosity in both estuary and canal. Sewage disposal into the canal decreased its dissolved oxygen content. The lower oxygen values in the estuary in June were accompanied with higher temperatures. The pH values were generally higher in the estuary and were also higher in June than in March.Eighty-six algal taxa were recorded, 45 of which were diatoms. The phytoplankton in the estuary was more abundant in March, due to the increase in currents and turbidity in June. The Chlorophyta, Conjugatophyta, Myxophyta and Bacillariophyta in the estuary showed reverse seasonal trends from those of the total phytoplankton. These algal seemed to flourish during periods of high temperatures. The dense blue-green algae recorded in June is attributed to the high temperature and dissolved organic matter. The Chrysophyta recorded high populations in the estuary in March and were totally absent in June. Lower temperatures and high transparency in March might have led to their relative abundance.The total phytoplankton in the Ashar Canal followed two different seasonal trends, one resembling and the other differing from those in the estuary. The disposal of domestic sewage and agricultural wastes in the canal seemed to lead to such adverse seasonal variations. The diatoms only dominated the phytoplankton at one station in both months. The sewage and agricultural wastes disposal seemed to favour the abundance of the other phyla than the diatoms. Increased organic load in the canal has led to a considerable increase in the Myxophyta in June. Blooms of Chlamydomonas sp. and Euglena acus increased the phytoplankton densities in March at stations II and IV, respectively. Benthic or periphytic algae were found in the phytoplankton populations. Raised salinity seemed to restrict the distribution of the planktonic diatom Bacillaria paradoxa. Among the noticeable widespread planktonic algae in the study area are Dinobryon sertularia, Pediastrum duplex and P. simplex.     

Phytoplankton flora in the Warri/Forcados Estuary of southern Nigeria

The phytoplankton flora of the Warri/Forcados estuary varied from typical fresh and brackish water forms to purely distinct marine species. These were made up of members of the Bacillariophyta (about 80 species), Chlorophyta (over 90 species), Cyanophyta (16 species), Dinophyceae (10 species) and the Euglenophyta (8 species). The bulk of the species belonging to the Chlorophyta, Cyanophyta and the Euglenophyta were almost exclusively fresh-water in distribution, being limited to habitats of less than 0.5 salinity. Members of the Bacillariophyta were found in all habitats, occurring freely in freshwater, estuarine, and marine ecosystems. In all cases, no true examples of euryhalinity were recorded. The majority of dinoflagellates encountered, as well as a number of marine diatoms, manifested stenohaline peculiarities as they could not tolerate a wide salinity range.The overall influence of the periodic shift in salinity and some physico-chemical parameters along the stretch of the estuary brought about by strong tidal effects and the variable seasonal volume of water discharge or runoff on the pattern and limit of distribution of phytoplankton species is highlighted.     

Phytoplankton biodiversity in the two perennial lakes of Coimbatore,Tamil Nadu,India

The present study was focused to evaluate the phytoplankton biodiversity in two freshwater perennial lakes of Sulur and Ukkadam of Coimbatore District, Tamil Nadu, India. The study period was two years from March 2012 to February 2014. Results revealed that totally 50 species of phytoplankton include 14 Cyanophyceae, 19 Chlorophyceae, 14 Bacillariophyceae, and 3 Euglenophyceae were recorded from the Sulur lake and 36 species of phytoplankton comprising 9 species of Cyanophyceae, 15 species of Chlorophyceae, 10 species of Bacillariophyceae and 2 species of Euglenophyceae were noticed in Ukkadam lake during the study period. The recorded phytoplankton density was ranged between 22,380 and 80,590 cells/l in Sulur lake and 29,350 and 1,16,255 cells/l in Ukkadam lake. Thus, the present study overall dominance of phytoplankton group was Chlorophyceae followed by Cyanophyceae, Bacillariophyceae, and Euglenophyceae. The phytoplankton population was recorded maximum in Ukkadam lake when compared to Sulur lake. Hence, the study revealed that both Ukkadam and Sulur lakes possess an appreciable quantum of phytoplankton and it can be used for fish culture.     

长江口及其邻近水域网采浮游植物群落

根据2006年2月～11月在长江口及其邻近水域的采样调查,对调查水域网采浮游植物群落结构特征进行了研究.共鉴定出浮游植物5门72属177种(包括未定名种),浮游植物以硅藻为主,但甲藻在群落中的比重也很明显,此外还有少量的绿藻、蓝藻和金藻.浮游植物优势物种以可形成链状群体的物种为主,中肋骨条藻(Skeletonema costatum)在长江口水域全年都具有较高的优势度,另外还有季节性的优势种,春季的夜光藻(Noctiluca scientillans)和具齿原甲藻(Prorocentrum dentatum),夏季的细长翼鼻状藻(Proboscia alata f. gracillima),秋、冬季的琼氏圆筛藻(Coscinodiscus jonesianus)和星脐圆筛藻(Coscinodiscus asteromphalus).浮游植物物种多为温带近岸种,少数为暖水种或大洋高盐种.长江口水域网采浮游植物的细胞平均丰度在夏季最高,为2027.41×104 cells m-3,其次为春季,秋季最低,为22.15×104 cells m-3.冬季的细胞丰度在各站之间变化幅度是最小的.浮游植物物种组成、细胞丰度及多样性指数在区域上和时间上都表现出明显的差异.调查所获4季度月网采浮游植物的丰度资料与历史资料基本吻合,季节变化也基本一致,但也有个别季度差别较大,长江径流量的年际变动可能是造成这种差别主要原因之一.     

Structural variations of phytoplankton in the coastal seas of Yucatan,Mexico

A study was done of the relationship between hydrographic variables and the composition, abundance, community structure and biomass spectrums of coastal phytoplankton at scales greater than 100 km on the Yucatan Peninsula (SE Gulf of Mexico). This was done during the season of greatest environmental instability in the region, the northwind season (late fall to winter). Samples were collected at stations in the west (Campeche), north (Yucatan), and east (Quintana Roo) zones of the Peninsula. Measurements were taken of temperature, salinity, dissolved oxygen, dissolved inorganic nutrients (ammonia, nitrite, nitrate and phosphate) and chlorophyll a, and samples were taken for phytoplankton analysis. The hydrographic results showed the Campeche zone as having the lowest salinity (<35 psu) values, as well as the highest inorganic nutrient and chlorophyll a values, all of which are related to continental water contributions. The Yucatan zone had the lowest temperatures and the lowest inorganic nutrient values, indicating influence from the Yucatan Current and the Gulf of Mexico. A total of 159 phytoplankton species were identified, dominated by diatoms (>80%) and dinoflagellates. Phytoplankton exhibited greater concentration, richness, equitability and diversity in Campeche, while the lowest community structure values were had in the Quintana Roo zone. The ordination analysis demonstrated that the dominant genera were the diatoms Chaetoceros, Pseudonitzschia and Thalassionema. The biomass spectrums exhibited the lowest slope in environments of higher heterogeneity, with Campeche being the most disturbed and heterogeneous zone and Quintana Roo that with the least heterogeneity.     

珠江口广州段浮游植物群落特征研究

2008～2010年对珠江口广州段浮游植物进行了12个航次现场调查,共鉴定出浮游植物185种。中肋骨条藻(Skeletonema costatum)和颗粒直链藻(Melosira granulate)及其最窄变种(Melosira granulate v.angustissima)为主要优势种,并有明显的季节演替现象。调查期间,珠江口广州段浮游植物细胞数的平均值为5.51×10⁵cells/L,且浮游植物细胞数量存在年间变化。通过比较各年的Shannon-Wiener多样性指数和Pielou均匀度年均值,结果表明,2010年的生态环境较2008年和2009年好,浮游植物群落结构较稳定。经相关性分析,磷酸盐为调查河口区浮游植物生长繁殖主要影响因子。     

近15年长江口海域海洋生物变化趋势及健康状况评价

对近15年(2004—2018年)长江口海域海洋生物变化趋势进行分析,评价海洋生物健康状况,并对陆源污染物排放与海洋生物变化进行相关性分析。结果表明,(1)长江口海域海洋生物群落结构组成发生了一定变化,与20世纪90年代末相比,浮游植物种类数有所减少,浮游动物、底栖生物种类数有所增加。浮游植物以硅藻为主,但甲藻占比有所增加,2010年以来硅藻、甲藻群落结构进入新的平衡状态;浮游动物以节肢动物为主,主要类群桡足类占比有所下降;底栖生物种类数明显升高。(2)生物多样性总体水平一般,浮游植物多样性指数总体较低,第一优势种的优势度较高;浮游动物多样性指数和丰富度指数多年呈现下降趋势;底栖生物多样性水平一般,优势种渐趋单一。(3)海洋生物总体处于"不健康"状态,主要影响指标为浮游植物密度偏高,浮游动物密度偏低、生物量偏高,底栖动物密度偏高、生物量偏低。生态系统变化与陆源主要污染物排放、营养结构变化及水体富营养化均具有一定的相关性,其中无机氮(DIN)、石油类入海通量与生物健康指数呈显著负相关关系(P<0.05),无机磷(DIP)与底栖生物生物量呈显著负相关关系。N/P与浮游植物丰度呈显著负...     

Ecological studies of phytoplankton in Tai Tam Bay,Hong Kong

Of the 141 phytoplankton species found during the sampling period, the Bacillariophyceae was the most important group and included 70% of the total number of species; the Dinophyceae comprised a smaller percentage (28%) of the taxa; and only 3 chrysophyte species occurred throughout the study period. In terms of numbers of individuals, the Bacillariophyceae remained as the dominant group and contained 97% of the total numbers whereas the Dinophyceae represented only 3% of the total phytoplankton population.The most dominant diatom species was Thalassiosira allenii Takano which constituted 35% of the Bacillariophyceae group whereas the most abundant dinoflagellate was Prorocentrum gracile Schutt which represented 40% of the total Dinophyceae numbers.Chlorophyll a levels varied from 0.40 to 32.31 mg m^–3 at the surface and from 0.33 to 33.91 mg m^–3 at the bottom.Seasonal trends of phytoplankton abundance and chlorophyll a concentration were observed in the survey area with generally high peaks in summer and low values during winter months. Such variations can be attributed to the interactions between, and changes of, various environmental parameters, such as temperature, salinity and nutrient availability (particularly silicate).     

Seasonal variation of phytoplankton community in Thale Sap Songkhla, a lagoonal lake in southern Thailand

The phytoplankton in Thale Sap Songkhla was investigated at 2–3 month intervals from August 1991 to October 1993. The abundance of phytoplankton ranged from 1.4×10⁶ to 1.3×10⁹ cells m^–3. A total of 6 divisions with 103 genera were identified as Bacillariophyta: 49 genera, Chlorophyta: 21 genera, Pyrrhophyta: 15 genera, Cyanophyta: 12 genera, Chrysophyta: 3 genera and Euglenophyta: 3 genera. Although phytoplankton abundance was distinctly greater in the first year of study (August 1991–June 1992) than in the second year (August 1992–October 1993), their patterns are similar: 2 peaks yearly. The peaks of phytoplankton occurred in the heavy rainy season (northeast monsoon) and the light rainy season (southwest monsoon). The main bloom was found during December–January, with a predominance of blue-green algae (e.g. Aphanizomenon andPhormidium) and green algae (e.g. Eudorina). Their species composition also increased, an effect of the large amount of rainfall resulting in low salinity during the northeast monsoon. The minor bloom was produced by diatoms during June–July when water salinity was moderate to seawater. Both phytoplankton numbers and species composition were high. However, unpredictably heavy rainfall during the southwest monsoon period may reduce diatom production due to rapid immediate replacement by blue-green species. Besides salinity concentration, a low total nitrogen: total phosphorus (TN: TP) ratio tended to support the growth of blue-green algae. The diversity of phytoplankton was lowest in the heavy rainy period.     

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.     

西江下游浮游植物群落周年变化模式

西江肇庆段是珠江干流汇入珠三角河网水域的咽喉通道,对2009年该江段的浮游植物群落组成及变化进行系统阐析.调查期间共发现浮游植物7门,245种(包括变种、变型),其中硅藻和绿藻是浮游植物群落组成的最主要类群,分别占总种数的42.44％和34.69％,其次是裸藻和蓝藻.PCA分析结果显示,浮游植物各类群的种类丰富度和生物量的周年变化趋势主要受水温和径流量的影响.浮游植物种类丰富度的周年变化呈现明显的高温季节高,低温季节低的特征,除因大多数藻类物种直接喜好高温之外,径流量的增大有助于真浮游绿藻种类的外源注入及半浮游和偶然性浮游硅藻种类的增加.浮游植物生物量的周年变化呈现明显的双峰型,峰值分别出现在8月和11月.然而8月份第1个高峰出现之前,生物量波动不大,尽管水温的升高有助于生物量的增加,但是径流量增大所带来的稀释作用掩盖了水温上升对浮游植物生长的促进作用.真浮游植物生物量的变化趋势和数值与总浮游植物极其接近,主要得益于真浮游硅藻物种颗粒直链藻在总种群中的绝对优势地位.综上,水温升高对浮游植物种类丰富度和生物量的增长均有促进,径流量的增大虽然有助于种类丰富度的增加,但不利于生物量的增加.     

Seasonal distribution of phytoplankton in the Aby lagoon system,Ivory Coast,West Africa

Seasonal variability of phytoplankton species composition, abundance and physical and chemical factors influencing phytoplankton dynamics were investigated in the Aby lagoon system, south-eastern Ivory Coast, covering the main climatic seasons in 2006–2007. Seasonal and spatial variability of nutrient concentrations in the system were influenced by freshwater inflow from the Bia and Tanoé rivers. The decrease in the salinity gradient in Aby Lagoon, which is permanently stratified during the long dry season, increased the bottom inputs of soluble reactive phosphate and soluble reactive silicate which, in combination with good light penetration during the long dry season, enhanced phytoplankton production in the system. During the rainy seasons, water discharges into the system washed phytoplankton biomass out, preventing the development of blooms. Overall, 192 taxa from eight phyla were recorded: Bacillariophyta (32%), Chlorophyta (31%), Cyanobacteria (23%), Euglenophyta (12%), Dinophyta (0.5%), Xanthophyta (0.5%), Chrysophyta (0.5%) and Rhodophyta (0.5%). During the long dry season, Cyanobacteria cells comprised >50% of the phytoplankton abundance. The main phytoplankton taxa responsible for this high abundance were Microcystis aeruginosa, Oscillatoria princeps, Pseudanabaena limnetica, Aphanizomenon sp. 2 and Anabaena planctonica.     

春末三峡大坝首次蓄水期长江口浮游植物群集

根据2003年6月三峡大坝第1次蓄水期长江口及其邻近水域(28°-33°N,120°-125°E)34个测站采集的浮游植物水样,报道了该水域浮游植物群集特征.结果表明:调查区浮游植物以硅藻和甲藻为主,伴有少量的绿藻和金藻.浮游植物细胞丰度介于0.2～1504.2 cells·ml-1,平均为72.7 cells·ml-1,主要优势物种为骨条藻(Skeletonema sp.)、具齿原甲藻(Prorocentrum dentatum)和锥状施克里普藻(ScrippsieUa trochoidea).调查区表层两个浮游植物密集区分别位于北部的冲淡水域和西南部近岸水域.浮游植物细胞丰度最大值出现在中层(10m层),最小值出现在底层.冲淡水域的优势物种是骨条藻,主要出现在表层;而在长江冲淡水与台湾暖流、黄海混合水交汇的水域,优势物种为具齿原甲藻,主要分布在表层和中层.     

珠江口南沙河涌浮游植物群落结构时空变化及其与环境因子的关系

随着城市生态健康理念的提出,城市河涌生态健康也受到了前所未有的关注。为更好的了解河涌的水环境和浮游植物现状,于2015年3月至2016年2月对珠江口南沙河涌8个站位水环境和浮游植物群落结构进行调查。结果显示:共发现浮游植物164种(属),隶属7门73属,其中以绿藻种类最多,达33属79种,占48.17%;硅藻次之,17属41种,占25%。优势种为梅尼小环藻(Cyclotella meneghiniana)、假鱼腥藻属(Pseudanabaena sp.)和小球藻(Chlorella vulgaris)。浮游植物细胞密度在0.19×10~6—101.34×10~6个/L内变动,呈现单峰型,在4月发生拟菱形弓形藻(Schroederia nitzschioides)水华,14涌密度高达87.38×10~6个/L,随后因强降雨细胞密度骤降。浮游植物群落的季节演替基本符合PEG(Plankton Ecology Group)模型,从冬季的硅藻,到春夏季的绿藻,再到秋季的蓝藻。One-way ANOVA分析显示,各月份浮游植物细胞密度差异显著(P0.01)。Pearson相关性分析表明绿藻细胞丰度变化主导着浮游植物总丰度的变化(r=0.454,P0.01)。运用Margalef物种丰富度指数、Shannon物种多样性指数、Pielou均匀度指数对水体进行评价表明,调查水体呈中度污染。相关加权营养状态指数表明,河涌全年处于富营养化状态。浮游植物聚类分析表明,时间异质性较高,总体相似性较低;空间上相似性较高,人为活动可能是导致空间差异的关键因子。冗余分析显示,叶绿素a、溶解氧、盐度、水温、总氮和p H与浮游植物群落结构关系最为密切。p H对硅藻门浮游植物影响较大,碱性条件适宜直链藻生长,春季水华形成的驱动因子是盐度、温度和总氮。     

Changes in community structure and photosynthetic activities of total phytoplankton species during the growth,maintenance, and dissipation phases of a Prorocentrum donghaiense bloom

The potential interactions between the bloom-forming dinoflagellates and other phytoplankton during the algal bloom cycle are interesting, while the causes for the phytoplankton community changes were not fully understood. We hypothesized that phytoplankton community structure and photosynthetic activities of total phytoplankton have their special characteristics in different phases of the algal blooms. To test this hypothesis, a survey covering the process of a Prorocentrum donghaiense bloom in coastal waters between Dongtou and Nanji Islands was carried out from 9 to 20 May 2016, and the changes in the phytoplankton community and photosynthetic activities of total phytoplankton were determined. Surface seawater was sampled for microscopic analysis of phytoplankton composition and pulse amplitude modulated (PAM) chlorophyll fluorescence analysis of photosynthetic activities of the total phytoplankton species. A total of 25, 31, and 19 phytoplankton species were identified in its growth (9–12 May), maintenance (13–18 May) and dissipation phases (19–20 May), respectively. Diatoms were dominant in terms of species number while dinoflagellates were predominant at cell abundance. Dinoflagellates were the major dominant species during three phases of the bloom based on the dominance (Y) value, whereas the dominant species extended to dinoflagellates and diatoms including P. donghaiense, Coscinodiscus argus, Gonyaulax spinifera, Cyclotella sp. and Scrippsiella trochoidea in the dissipation phase. In the maintenance phase, the average cell abundances of the total phytoplankton and P. donghaiense were consistent with the chlorophyll a (Chla) concentration in the seawater; for the diversity indices of total phytoplankton species, Simpson index (C) was the highest while Shannon index (H′) and Pielou evenness index (J′) were the lowest. Furthermore, photosynthetic activities of the total phytoplankton species represented by the effective quantum yield (F_q'/F_m') and the maximum relative electron transport rate (rETR_max) in the maintenance phase were higher than those in the growth and dissipation phases. The results indicated that the characteristics of phytoplankton community structure and photosynthetic activities could be regarded as criteria in predicting the phases of algal blooms.     

Temporal Coherence of Chlorophyll a during a Spring Phytoplankton Bloom in Xiangxi Bay of Three‐Gorges Reservoir,China

Algal bloom phenomenon was defined as “the rapid growth of one or more phytoplankton species which leads to a rapid increase in the biomass of phytoplankton”, yet most estimates of temporal coherence are based on yearly or monthly sampling frequencies and little is known of how synchrony varies among phytoplankton or of the causes of temporal coherence during spring algal bloom. In this study, data of chlorophyll a and related environmental parameters were weekly gathered at 15 sampling sites in Xiangxi Bay of Three‐Gorges Reservoir (TGR, China) to evaluate patterns of temporal coherence for phytoplankton during spring bloom and test if spatial heterogeneity of nutrient and inorganic suspended particles within a single ecosystem influences synchrony of spring phytoplankton dynamics. There is a clear spatial and temporal variation in chlorophyll a across Xiangxi Bay. The degree of temporal coherence for chlorophyll a between pairs of sites located in Xiangxi Bay ranged from –0.367 to 0.952 with mean and median values of 0.349 and 0.321, respectively. Low levels of temporal coherence were often detected among the three stretches of the bay (Down reach, middle reach and upper reach), while high levels of temporal coherence were often found within the same reach of the bay. The relative difference of DIN between pair sites was the strong predictor of temporal coherence for chlorophyll a in down and middle reach of the bay, while the relative difference in Anorganic Suspended Solids was the important factor regulating temporal coherence in middle and upper reach. Contrary to many studies, these results illustrate that, in a small geographic area (a single reservoir bay of approximately 25 km), spatial heterogeneity influence synchrony of phytoplankton dynamics during spring bloom and local processes may override the effects of regional processes or dispersal. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Influence of terrestrial runoff on phytoplankton species richness-biomass relationships: A double stress hypothesis

The relationship between biomass and species richness (SR) was studied along productivity gradients in coastal phytoplankton assemblages under the influence of terrestrial runoff. In particular, the investigation focused on (a) whether phytoplankton blooms affect the shape of the relationship, (b) whether the relationship is taxon specific (between dinoflagellates and diatoms), and (c) the potential mechanisms regulating the shape of the relationship. Analysis was based on phytoplankton and physicochemical data from six coastal areas in the Aegean Sea, Eastern Mediterranean, covering the whole range from oligotrophy to eutrophication. A SR-biomass relationship was not observed for the more oligotrophic areas, whereas hump-shaped curves were found in areas yielding higher maximum biomass values, corresponding to bloom events occurring mainly during winter. Furthermore, the observed hump-shaped relationships were taxon specific since they were more pronounced in the case of diatoms than dinoflagellates. It is hypothesized that SR at the leftmost part of the hump-shape is nutrient regulated, whereas at the rightmost part is limited by extreme abiotic stress occurring during the formation of blooms in coastal ecosystems. The results of this study suggest that a double stress mechanism related to abiotic factors may be responsible for the hump-shaped SR-biomass relationships occurring in coastal phytoplankton communities at various levels of productivity.