东湖沿岸带底栖藻类群落的时空变化

武汉东湖是一个浅水富营养湖泊,其沿岸带底栖藻类群落的季节分布特征明显,夏季的优势种群是一些体积很小的硅藻类曲壳藻(Achnanthes spp.),其他大部分季节是绿藻门的团集刚毛藻(Cladophora glomerata)和硅藻门的变异直链藻(Melosira varians)。不同样点间的底栖藻类现存量差异不显著,但优势种类不同,以团集刚毛藻为优势的绿藻在处于中富营养区域的磨山样点比例最高,以变异直链藻为优势种的硅藻在严重富营养化的水果湖样点中比例最高。底栖藻类月平均现存量(以叶绿素a计)的时间变化格局为夏季最低(41.5μg/cm2),逐渐增加到秋、冬季节的最高峰值(55.3μg/cm2)。造成东湖夏季底栖藻类现存量低的原因是雨季水体环境的不稳定性和水位升高造成的低光照。不同样点间的chlb、chlc及chlb/a、chlc/a值具有显著差异,分析这种差异显示:在东湖的富营养化条件下,过渡的富营养化能增加底栖藻类群落中硅藻的比例,却降低了绿藻的比例;不同环境条件下的底栖藻类群落结构具有特异性,分析底栖藻类群落结构可以用来评价水环境健康状况。东湖底栖藻类现存量的季节变化规律与浮游藻类不同,它和水温成显著的负相关,但温度和浮游藻类并不是影响东湖沿岸带底栖藻类生物量变化的直接因子。团集刚毛藻等底栖丝状藻类给各种底栖动物提供了食物和栖息环境,在东湖生态系统中具有重要的作用和功能。     

雅砻江（锦屏段）及其主要支流底栖藻类群落与环境因子的关系

分别于2004年5月和11月对雅砻江(锦屏段)及其主要支流22个采样点的底栖藻类进行研究.共采获底栖藻类150种,分属3门(硅藻、绿藻和蓝藻),37属.其中硅藻门占绝对优势(96.5%),线性曲壳藻(Achnanthes linearis)和Achnanthes deflexa为绝对优势种,其相对丰富度分别为35.3%和11.0%.细端菱形藻(Nitzschia dissipata)和小型异极藻(Gomphonema parvulum)是雅砻江(锦屏段)干流的优势种,而线性曲壳藻、扁圆卵形藻(Cocconeis placentula)和Achnanthes deflexa是其他支流的优势种.基于底栖藻类的物种组成和相对丰度,对两次的采样点进行去势对应分析(DCA),结果发现:两次采样雅砻江(锦屏段)干流样点与其他支流样点在DCA第一轴上得到了很好的分化,表明研究区域底栖藻类群落存在明显的空间差异,这主要是由干流的特殊生境所致.典范对应分析(CCA)结果显示不同季节影响底栖藻类群落结构的环境因子有所差异.总磷(TP)是5月份影响底栖藻类空间分布的最主要因素;11月份影响底栖藻类空间分布的最主要环境因子为氨氮(NH4-N)和海拔(Elevation).     

人工试验湖泊浮游藻类群落的生态学研究

为了对转基因(CAgcGH)鲤的生态风险评估提供参考资料, 于2002年构建人工试验湖泊。研究分析了该人工湖泊浮游藻类群落的结构特征、季节动态、年际变化及其与水体各环境因子的关系。2006年至2010年间, 每季度采样, 共鉴定出浮游藻类7门47属66种, 其中绿藻种类最多。双向指示种分析(TWINSPAN)和除趋势对应分析(DCA)结果显示采样点数据可分为春夏秋冬4组, 说明该群落季节性明显。冬季群落结构简单, 多样性最低, 主要由小环藻(Cyclotella sp.)和分歧锥囊藻(Dinobryon divergens)组成; 春季, 小环藻、针杆藻(Synedra sp.)、颗粒直链藻(Melosira granulata)等几种硅藻占优势; 夏季群落结构复杂, 占优势的是银灰平裂藻(Merismopedia glauca)和螺旋鞘丝藻(Lyngbya contarta), 多样性最高; 秋季没有明显占优势的种类。5年间, 群落细胞密度上升了33.1%, 平均值为(1.430.75)106 cells/L; 硅藻在群落中所占比例从48.2%下降至16.2%, 而蓝藻从9.3%上升至42.2%。典范对应分析(CCA)的结果显示对浮游藻类影响最大的环境因子是温度和溶氧, 总氮浓度和总磷浓度的影响也是不可忽视的, 而pH在试验中对浮游藻类群落结构的影响有限。不同藻类在CCA排序图上有不同的分布格局, 一些硅藻主要分布在中低温采样点, 蓝藻集中分布在高温的采样点, 鼓藻主要出现在高透明度和高总磷浓度的采样点, 金藻主要分布在高溶氧浓度和低温的采样点。       

东洞庭湖浮游藻类群落的结构特征及物种多样性分析

2013~2014年对东洞庭湖浮游藻类种类组成和种群密度进行了取样调查,对其物种多样性和群落结构的时间和空间变化进行了分析。结果如下:1)共鉴定出该水域浮游藻类8门65属159种(含变种和变型),较前人有所增加,其中硅藻种类数量增幅较大;2)浮游藻类的平均密度为每升6.14×10~4个,平均生物量为0.20 mg/L,平均密度和生物量调查结果较前人均偏小;3)优势种主要有变异直链藻(Melosira varians)、颗粒直链藻(Melosira granulata)、啮蚀隐藻(Cryptomonas erosa)等16种,具有明显的季节变化;4)Shannon-Weiner多样性指数总平均值为4.11;Margalef丰富度指数总平均值为5.58;在季节变化上呈现出一致的趋势,均为3月11月6月9月,枯水期的物种多样性高于丰水期。Pielou均匀度指数总平均值为0.63。各采样点相比,八仙桥和扁山的多样性指数较小,荆江口最大;5)位于东洞庭湖东侧各采样点群落结构较为相似,与位于西侧和新墙河的样点差异较大;冬春季节的群落结构与夏秋季节存在一定差异。     

珠海淇澳岛红树林和芦苇湿地底栖硅藻群落比较

研究了珠海淇澳岛红树林湿地和芦苇湿地2007年3月至2008年1月间底栖硅藻群落的结构及其动态特征.结果表明,两种湿地共有底栖硅藻28属113种(变种),其中红树林中检出23属95种(变种),明显高于芦苇湿地的21属42种(变种).底栖硅藻的丰度为14.3～553.5 celk cm-3,不同样地和采样期的多样性指数和均匀度指数不同,但红树林湿地高于芦苇湿地.两种湿地底栖硅藻群落的属种结构存在显著差异,红树林湿地中多以羽纹藻类,如布纹藻属(Gyrosigma)、斜纹藻属(Pleurosigma)和羽纹藻属(Pinnularia)等占优势,而芦苇湿地主要以中心藻类,如圆筛藻属(Coscinodiscus)和小环藻属(Cyclotella)等占优势.相似性分析显示,样地基质对底栖硅藻群落的影响大于季节变化的影响.     

北京四校园人工湖浮游藻类与富营养化特征分析

浮游藻类作为重要的生物指标已被广泛运用于各种水体的富营养化监测与评价中.论文对北京市4个校园人工湖的浮游藻类群落组成及季节变化展开调查,探讨了浮游藻类生物指标和富营养化的关系及其季节变化规律.调查期间,镜鉴得到39个属,隶属于蓝藻,绿藻和硅藻门.4个水体生物密度的季节平均值均高于500 cell·mL^-1,多样性指数普遍介于2～3之间.TN,TP和COD显示各水体都已处于富营养化状态.综合生物指标和水质指标进行聚类分析,结果显示:4个人工湖不同季节的水体可分为绿藻型,蓝,绿藻型和硅藻型三大类富营养化水体:荷花池,荷塘浮游藻类群落相似性最高,而荷塘、未名湖夏季富营养化程度最接近.     

广东鉴江水系底栖硅藻多样性与时空分布特征

为了解广东省鉴江水系底栖硅藻多样性和时空分布特征,对全流域进行了底栖硅藻采样调查。结果表明,从19个采样点4次采样中共检出底栖硅藻10科52属242种,其中舟形藻属(Navicula)、菱形藻属(Nitzschia)和异极藻属(Gomphonema)是优势类群,出现频次和相对丰度较高。硅藻多样性指数(丰富度、真香农多样性指数和真辛普森多样性指数)随河流等级呈现一定的空间分布特征,但它们季节变化不明显。底栖硅藻群落相异性在上游和下游河段较高,从一级到三级河流递减,四级河流又增加。底栖硅藻群落结构空间变化明显,季节变化显著。群落丰富度的稀疏曲线表明,热带河流底栖硅藻群落以400个体计数,不能完整反映底栖硅藻多样性。这些为鉴江水系河流健康监测和水生态保护奠定了基础。     

山东半岛典型海域大叶藻(Zostera marina)附着大型藻类群落结构

2012年3月、6月、9月和12月对青岛栈桥、威海双岛湾及荣成月湖3个典型海域大叶藻(Zostera marina)草场的附着大型藻类进行了调查,采用多样性指数、均匀度、聚类和排序等多元统计方法对各海域不同季节附着藻类的群落结构进行比较分析。结果表明:鉴定大型藻类17种,隶属3门14属,其中红藻门4属5种、褐藻门4属4种和绿藻门6属8种;三海域附着藻类种数最大值均出现在春季的栈桥和月湖(均为7种),最小值出现在秋季和冬季的月湖(均为1种);三海域附着藻类生物量最高值均出现在春季,而最低值分别为秋季(栈桥)、冬季(双岛)和夏季(月湖);栈桥的Shannon多样性和Pielou均匀度指数最低,双岛的物种多样性指数最高;一年中夏季的物种多样性和均匀度指数最高,冬季最低;聚类和排序结果表明,不同季节附着藻类群落结构在海域间和海域内不同采样点间均呈现显著性差异。季节变化和地域的差异对大叶藻附着藻类的群落结构特征有着重要影响。     

盐城自然保护区射阳河口潮间带大型底栖动物空间分布与季节变化

2008年11月—2009年10月,在盐城自然保护区射阳河口潮间带按月份对大型底栖动物群落进行取样。共得到大型底栖动物16种,隶属3门4纲15科,为软体动物、节肢动物甲壳类和环节动物多毛类,其中,潮间带米草丛6种,高潮带光滩7种,中潮带光滩13种,低潮带光滩7种。对潮间带各样点的物种数、密度、生物量以及不同样点的生物多样性指数Margalef指数(S)、Shannon指数(H)、Pielou指数(J)和Simpson指数(D)进行样点-季节间无重复双因素方差分析,发现样点间物种数、密度和生物量差异极显著(所有P<0.01),三者季节间差异均不显著;样点间H、D和S差异显著(所有P<0.05),季节间差异均不显著;而季节间和样点间J差异均不显著。对四季4个样点的群落进行聚类和排序分析发现,中、高潮带光滩界限不明显,潮间带米草丛和低潮带光滩界限明显。结果表明:生境条件的不同是潮间带大型底栖动物群落组成差异的主要原因,同一生境大型底栖动物群落季节间差异不显著。     

基于附石硅藻的三峡水库入库支流氮、磷阈值

为全面了解河流附石硅藻群落对水体氮、磷变化的响应规律,并找出氮、磷指示物种,本研究采用非参数突变点分析法(nCPA)及临界指示物种分析法(TITAN)探讨了三峡水库入库支流附石藻类叶绿素a、硅藻物种丰富度、Shannon多样性指数以及硅藻群落组成的总氮(TN)、总磷(TP)阈值.结果表明: 据nCPA得到的所有藻类参数的TP阈值均接近0.03 mg·L^-1;除硅藻群落组成外,其他参数的TN阈值也较接近(约为0.8 mg·L^-1).TITAN区分了群落中敏感种、耐受种对TN、TP变化的响应,且阈值范围涵盖了其他参数的阈值;还确定了9种TN指示种和10种TP指示种,其中TN敏感种1种,耐受种8种;TP敏感种5种,耐受种5种.因此,本研究以TITAN结果为依据确定河流的TN、TP阈值.即:当河流TN浓度低于0.382 mg·L^-1或TP浓度低于0.016 mg·L^-1时(负响应阈值),河流附石硅藻群落组成相对稳定;超过这一浓度阈值后,敏感种密度减少;当河流的TN浓度超过1.298 mg·L^-1或TP浓度超过0.065 mg·L^-1时(正响应阈值),耐受种也将受到明显影响,附石藻类的群落组成会发生显著变化.据此标准,调查样点中约87%的样点TN浓度超过TN负响应阈值,22%的样点超过正响应阈值;而超过TP负响应阈值的点占94%,超过TP正响应阈值的点占14%,说明三峡水库大部分入库河流虽受到了一定程度的干扰,但干扰程度并不严重.本研究结果可为三峡水库入库河流生态管理决策提供科学依据.     

BENTHIC ALGAL COMMUNITIES OF THE METOLIUS RIVER1,2

Sampling of benthic algae from selected sites in the Metolius River was carried out at regular intervals between April 15, 1967 and March 9, 1968 to determine the species composition of the communities. With the exception of the sampling site at the headwaters and the site immediately downstream, the benthic community of the Metolius River is described as a Cladophora–Achnanthes–Spirogyra community, with species of these 3 genera predominating on a year-round basis. The community described for the headwaters and the sampling site immediately downstream was composed primarily of Nitzchia palea and Cymbella cistula. Of the approximately 60 species of algae which were identified, only 9 showed a definite seasonal distribution, the remaining species being found on a year-round basis.     

Phytoplankton communities in navigation pool no. 7 of the Upper Mississippi River

A study of the phytoplankton community dynamics in Navigation Pool No. 7 of the Upper Mississippi River was conducted from May through October, 1982. The objectives of this study were to estimate total standing crops, determine the taxonomic composition and examine the seasonal succession of the phytoplankton community. Four sampling sites were established: two in Lake Onalaska, a large backwater lake on the Wisconsin side of the main channel; one in the main channel near Dakota, Minnesota; and one in the main channel just upstream from Lock and Dam No. 7.The phytoplankton communities at all sampling sites were dominated by diatoms except during July and August when a bloom of blue-green algae was observed. The dominant diatoms from May through mid-July were Melosira italica, Stephanodiscus niagarae, Stephanodiscus hantzschii, Stephanodiscus astrea, and Synedra ulna. Aphanizomenon flos-aquae and Microcystis aeruginosa were the most prevalent blue-green algae during the mid-summer bloom. The diatoms Melosira italica and Melosira granulata were dominant in September and October. Lesser amounts of green algae, cryptomonads and euglenoids were also observed at various times of the sampling period.Total standing crops based on cell volume were usually greatest at the Lock and Dam No. 7 site. The maximum standing crop (10.4 mm³ 1^–1) was observed at the Lock and Dam No. 7 site on 4 September; the minimum standing crop (0.4 mm³ 1^–1) was observed at the eastern Lake Onalaska site on the same date. Concentrations of nitrogen, phosphorus, and silica remained at high levels throughout the study period and did not appear to limit phytoplankton standing crops.     

Benthic algal response to hyporheic-surface water exchange in an alluvial river

We studied the response of benthic algae to points of hyporheic-surface water exchange in the main channel of the Middle Fork Flathead River within the Nyack Flood Plain, Montana. We examined hyporheic exchange at 120 sites using piezometers and measuring vertical hydraulic gradient (VHG), hydraulic conductivity, and vertical discharge. We removed benthic algae from a single cobble at each site, and we used VHG to group sampling sites for statistical analysis. Algal cell density and chlorophyll a concentration were significantly higher at sites with hyporheic discharge (+VHG, upwelling) compared to both sites with hyporheic recharge (−VHG, downwelling) and sites with no hyporheic-surface water exchange (=VHG, neutral) (ANOVA, P < 0.05). The assemblages of algae at upwelling sites were also significantly different from downwelling and neutral exchange sites (ANOSIM, P < 0.05). Filamentous green algae Stigeoclonium sp. and Zygnema sp. and a chrysophyte, Hydrurus foetidus (Villars) Trevisan were abundant at upwelling sites, whereas an assemblage of diatoms Achnanthidium minutissimum (Kützing) Czarnecki, Cymbella excisa Kützing, Diatoma moniliformis Kützing, and Gomphonema olivaceoides Hustedt, were the most abundant taxa at downwelling and neutral exchange sites, occurring attached to, or in close association with the stalks of Didymosphenia geminata (Lyngbye) Schmidt. These data show that benthic algal communities are structured differently depending on the direction of hyporheic flux in the main channel of a large alluvial river, suggesting that hyporheic-surface exchange may influence the spatial distribution of main-channel benthic algae in rivers with hyporheic-surface water connectivity. Handling editor: J. Padisak     

A study of the suspended algae in the River Derwent,Derbyshire, U.K.

Studies of the composition and abundance of algae suspended in the water of the River Derwent, Derbyshire, were made during 1983. Samples were collected at intervals of 2–3 weeks from 6 sites on the lower reaches of the river. Variations in both composition and abundance of suspended algae occurred with variations in flow. At the uppermost sites cell densities were generally low (<500 cells ml^–1) and the algae consisted mainly of dislodged benthic diatoms. The density in suspension of these algae of benthic origin increased with flow. At downstream sites a true potamoplankton developed; during the summer this consisted chiefly of centric diatoms with Chlorophyta and Cryptophyta. Even at the lowermost site, the maximum recorded density of cells (3 860 cells ml^–1) and cell load (30 × 10⁹ cells s^–1) were lower in the Derwent than in some other British rivers. However, the cell density could still represent a substantial part (up to 32%) of the total particle density in the river.     

A comparison of natural and human determinants of phytoplankton communities in the Kentucky River basin,USA

Physical, chemical, and biological characteristics of the Kentucky River and its tributaries were assessed for one year to compare effects of seasonal, spatial, and human environmental factors on phytoplankton. Phytoplankton cell densities were highest in the fall and summer and lowest in the winter. Cell densities averaged 1162 (± 289 SE) cells m1^–1. Cell densities were positively correlated to water temperature and negatively correlated to dissolved oxygen concentration and to factors associated with high-flow conditions (such as, suspended sediment concentrations). Chrysophytes, diatoms, and blue-green algae dominated winter, spring, and summer assemblages, respectively. Ordination analyses (DCCA) indicated that variation in taxonomic composition of assemblages was associated with stream size as well as season.Spatial variation in phytoplankton assemblages and effects of humans was investigated by sampling 55 sites in low flow conditions during August. Phytoplankton density increased with stream size. Assemblages shifted in composition from those dominated by benthic diatoms upstream to downstream communities dominated by blue-green algae and small flagellates. Human impacts were assumed to cause higher algal densities in stream basins with high proportions of agricultural or urban land use than in basins with forested/mined land use. While density and composition of phytoplankton were positively correlated to agricultural land use, they were poorly correlated to nutrient concentrations. Phytoplankton diversity changed with water quality: decreasing with nutrient enrichment and increasing with conditions that probably changed species composition or inhibited algal growth. Human impacts on phytoplankton in running water ecosystems were as great or greater than effects by natural seasonal and spatial factors. Our results indicated that phytoplankton could be useful indicators of water quality and ecosystem integrity in large river systems.     

Observations on standing crops of epipelic and epipsammic algal communities in Shear Water,Wilts

Methods of estimating the standing crops of epipsammic diatoms have been evaluated and compared with those used for epipelic algal crops.

Good correlations between chlorophyll a content and cell counts were obtained for epipelic populations, but because of the presence of large numbers of decaying cells, inseparable from living cells, such correlation was not obtained with epipsammic algae, even after correction of the pigment estimates for the presence of pheophytin a. The standing crop of epipsammic algae was at all times greater than that of epipelic algae at the same sampling station, and this was attributed to the differential effects of sediment disturbance by burrowing animals and water movements.     

Response of an algal assemblage to nutrient enrichment and shading in a Hawaiian stream

To investigate the effects of nitrate enrichment, phosphate enrichment, and light availability on benthic algae, nutrient-diffusing clay flowerpots were colonized with algae at two sites in a Hawaiian stream during spring and autumn 2002 using a randomized factorial design. The algal assemblage that developed under the experimental conditions was investigated by determining biomass (ash-free dry mass and chlorophyll a concentrations) and composition of the diatom assemblage. In situ pulse amplitude-modulated fluorometry was also used to model photosynthetic rate of the algal assemblage. Algal biomass and maximum photosynthetic rate were significantly higher at the unshaded site than at the shaded site. These parameters were higher at the unshaded site with either nitrate, or to a lesser degree, nitrate plus phosphate enrichment. Analysis of similarity of diatom assemblages showed significant differences between shaded and unshaded sites, as well as between spring and autumn experiments, but not between nutrient treatments. However, several individual species of diatoms responded significantly to nitrate enrichment. These results demonstrate that light availability (shaded vs. unshaded) is the primary limiting factor to algal growth in this stream, with nitrogen as a secondary limiting factor.     

Spatial and temporal dynamics of phytoplankton communities along a regulated river system, the Nakdong River, Korea

The longitudinal distribution and seasonal fluctuation of phytoplankton communities was studied along the middle to lower part of a regulated river system (Nakdong River, Korea). Phytoplankton biomass decreased sharply in the middle part of the river (182 km upward the estuary dam), and then increased downstream reaching a maximum at the last sampling station (27 km upward the estuary dam). In contrast, there was little downstream fluctuation in species composition, irrespective of pronounced differences in nutrient concentrations (TN, TP, NO₃, NH₄, PO₄) as well as in algal biomass. In the main river channel, small centric diatoms (Stephanodiscus hantzschii, Cyclotella meneghiniana) and pennate diatoms (Synedra, Fragilaria, Nitzschia) were dominant from winter to early spring (November–April). A mixed community of cryptomonads, centric and pennate diatoms, and coenobial greens (Pediastrum, Scenedesmus) was dominant in late spring (May–June). Blue-green algae (Anabaena, Microcystis, Oscillatoria) were dominant in the summer (July–September). A mid-summer Microcystis bloom occurred at all study sites during the dry season, when discharge was low, though the nutrient concentration varied in each study site. Nutrients appeared everywhere to be in excess of algal requirement and apparently did not influence markedly the downstream and seasonal phytoplankton compositional differences in this river.     

Limnological investigations on the Rosetta branch of the Nile. III. Phytoplankton

SUMMARY.

• 1 Seasonal qualitative and quantitative studies of the phytoplankton of the Rosetta branch of the River Nile are reported. Most of the genera were Bacillariophyceae, with Chlorophyceae and Cyanophyceae second and third. Only two genera of Dinophyceae were present. The phytoplankton can be broadly described as eurythermal and euryhaline.
• 2 Phytoplankton tended to be more concentrated in surface waters and showed large variations from station to station, with noticeably lower values in the estuarine region except in January.
• 3 Most of the genera were recorded at all times but seasonally the highest numbers of diatoms and green algae were found in July during a period of high temperature and low discharge whereas blue-greens achieved maximum density in October.