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.     

The phytoplankton of Great Bitter Lake,Egypt, including the impacts of nutrient-laden and heated effluents

A year-long survey of the phytoplankton and nutrients in Great Bitter Lake indicates that this is a severely eutrophic lake. Chlorophyll levels were consistently high (>30μg/l), especially in summer (>90μg/l). The phytoplankton community comprised mostly diatoms and blue-green algae, although dinoflagellates and green algae were important at times. Local effects of effluent from a drain coming from the city of Ismailia were evident, although the effect of tourist hotels at Palma Beach was not detectable. The discharge of heated water from a thermal power plant raised the water temperature in the impacted area by 13°C in autumn and 22°C in summer and also caused decreases in chlorophyll and phytoplankton abundance. Dissolved nutrient levels were high and, especially at the offshore station, had a rather constant ratio of dissolved inorganic nitrogen to phosphate. The distribution of phytoplankton and chlorophyll were related more to temporal, presumably seasonal, variation than proximity to point sources of pollution.     

Dynamics of ice algae and phytoplankton in Frobisher Bay

Summary Vertical and seasonal variations of ice algae and phytoplankton were studied in relation to their physico-chemical environments in Frobisher Bay from 1979 to 1986. The biomass, estimated by both chlorophyll a concentrations and cell counts, was greater in the ice algae than in the phytoplankton in the underlying sea-water during winter and spring. Algal distribution in the sea ice varied vertically and seasonally, while in the underlying water column the phytoplankton distribution was much less variable. The ice algal bloom occurred at the bottom of the ice, particularly in the lower 5 cm during late spring, while the phytoplankton bloom took place at depths between 1 and 10 m during early summer after the ice bloom was over. The community structure of the ice algae changed from pennate to centric diatoms as the ice melted. The centrics dominated through the fall, and then decreased as the pennates increased in dominance when the ice formed again in winter. Species diversity and number were greater in the sea ice than in the seawater, but they were similar vertically within each habitat. The evenness of the species distribution did not vary with ice thickness or water depth. Species composition, abundance and dominance of ice algae and phytoplankton continually change both vertically and seasonally. The differential abilities of the species to attain maximal growth rates under various environmental conditions may result in species succession. Evidence is given for the major role of environmental factors regulating the dynamics of ice algae and phytoplankton.     

The inshore marine ecosystem off the Vestfold Hills,Antarctica

The planktonic, ice/water interface, and benthic communities at three sites off the coast of the Vestfold Hills, Antarctica, were examined over a complete year.The planktonic flora and fauna were composed predominantly of oceanic species with diatoms and copepods the numerically dominant groups. Primary production was largely restricted to the summer months except for epontic algae which developed in spring. The zooplankton exhibited a similar seasonal cycle but lagged some months behind that of the phytoplankton.The ice/water interface (epontic) fauna consisted of species from the plankton and benthos. Copepods were major contributors; however, two amphipod species dominated. Seasonality of the fauna in this habitat was determined by ice formation and breakout, and development of ice algae.Each of the benthic substrates supported a characteristic macrofaunal assemblage, although infaunal amphipods and tanaids were similar at each site. Infauna exhibited a distinct seasonal cycle related to that of the primary producers whereas macrofauna showed no seasonal changes in abundance.Species composition of each community in this coastal antarctic region was comparable with that of similar habitats in other antarctic coastal areas, supporting the circumpolarity of antarctic marine communities.     

Seasonal succession of the phytoplankton in the upper Mississippi River

Species composition and seasonal succession of the phytoplankton were investigated on the upper Mississippi River at Prairie Island, Minnesota, U.S.A. Both the numbers and volume of individual species were enumerated based on cell counts with an inverted microscope. A succession similar to algal succession in the local lakes occurred. The diatoms were dominant during the spring and fall and blue-green algae were dominant during the summer. The algal concentrations have increased up to 40 fold the concentrations of the 1920's, since the installation of locks and dams. The maximum freshweight standing crop was 4 mg · l^–1 in 1928 (Reinhard 1931), 13 mg · l^–1 in 1975 a wet year, and 47 mg · l^–1 in 1976, a relatively dry year with minimal current discharge. The diatoms varied from 36–99%, the blue-green algae from 0–44% and the cryptómonads from 0–50% of the total standing crop. The green algae were always present but never above 21% of the biomass. The dominant diatoms in recent years were centric -Stephanodiscus andCyclotella spp. (maximum 50,000 ml^–1). The dominant blue-green algae wereAphanizomenon flos-aquae (L.) Ralfsex Born.et Flahault andOscillatoria agardhii Gomont (maximum 800 ml^–1). These algal species are also present in local lakes. Shannon diversity values indicated greatest diversity of algae during the summer months.     

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。       

Studies on the phytoplankton and other algae of Indrasagar tank,Udaipur, India

Summary A study has been made of the productivity and periodicity of phytoplankton of the Indrasagar tank, Udaipur, in relation to physicochemical characteristics. Variations in the physical and chemical characteristics of water over a period of one year are described.The Tank is of eutrophic type. Green algae dominated the phytoplankton both as regards number of species and number of individuals.A definite phytoplankton periodicity has been observed, the green algae dominating in the rainy and winter seasons and the blue-greens during summer.A correlation of the phytoplankton productivity and physicochemical characteristics of Indrasagar tank indicates that the Chlorophyceae have a wide range of adaptability; the growth of diatoms is promoted by silica, nitrates and phosphates; and the growth of blue-green algae is controlled by pH and temperature.     

Effects of the discharge of thermal effluent from a power station on Lake Wabamun,Alberta, Canada — The epipelic and epipsamic algal communities

1. The epipelic algal standing crops were increased by the discharge of thermal effluent into Lake Wabamun, particularly in the discharge canal at station (03–04) and 05.
2. The increase in the standing crop size of the epipelon was due to Oscillatoria amoena and O. borneti in the heated area, while the discharge canal provided the inoculum of the algae for the heated area of the lake.
3. At station (03–04) the increased standing crop size was also a function of increased light penetration to the sediment due to the heated effluent keeping an area of the lake free of ice during the winter.
4. The species composition of the diatoms was similar at all stations except in the discharge canal where there was a reduction in the number of diatom species.
5. Navicula cuspidate developed best in the discharge canal in the summer where water temperatures of 31°C were recorded.
6. Amphora ovalis var. pediculus was the dominant diatom species during the winter under ice-cover.
7. The heated effluent had no effect upon the standing crop or species composition of the epipsammon.
8. Results obtained from the sediment core study showed that the shallow littoral zone of the lake is very disturbed due to wind-induced wave action.

     

兰州五泉山的藻类及其分布

以兰州五泉山为该地藻种资源库,对其中水生、陆生生境中藻类的种类多样性、群落结构、分布特点进行了研究。结果发现该地藻类植物65种(含4变种),包括蓝藻、绿藻、硅藻和红藻,其中硅藻种类最多(29种),其它依次为蓝藻(24种)、绿藻(11种)和红藻(1种)。水体中共42种,硅藻最多,有26种,其次蓝藻8种,绿藻7种,红藻1种,不同水体中优势种和亚优势种不同。土壤生境中发现20种,蓝藻13种,绿藻4种,硅藻3种,且非洲席藻和小球藻分为优势种和亚优势种。7个种类在水、陆两大生境都有分布,而且它们主要是丝状蓝藻。     

Phytoplankton structure and diversity in the eutrophic-hypereutrophic reservoir Paso de las Piedras, Argentina

This study aimed at analyzing the phytoplankton structure and dynamics in Paso de las Piedras Reservoir, Argentina, through the study of dominant species, diversity and similarity in relation with the abiotic environment. Samples were collected weekly or biweekly (January 2004–June 2005) at four sampling stations. The reservoir experienced a seasonal progression in phytoplankton composition that underlines six successional periods, each one characterized by the dominance of one or a few species. Cyanobacteria, green algae and diatoms were the most important constituents of the reservoir’s phytoplankton. Cyanobacteria dominated during summer and early autumn, green algae during late autumn and early winter, and diatoms during winter and spring. A high abundance of R. lacustris (Cryptophyceae) was observed during late September and early October. The general pattern of species succession is coherent with the general model of plankton seasonal succession described by the PEG model; however, the major discrepancy is the extremely short clear water phase observed. Successional periods were associated with changes in abiotic variables, and they showed differences in ecological traits. Cyanobacteria-Dictyosphaerium, Cyclotella, Stephanodiscus and Anabaena-diatom periods were characterized by a low number of cells, high diversity, with both dominance and specific richness low. On the contrary, during Cyanobacteria and Cyanobacteria II periods, the highest abundance was observed associated with low diversity and high dominance.     

Effects of temperature on spring bloom dynamics of epilithic diatom communities in the Gulf of Bothnia

Abstract. In order to forecast consequences of climatic changes for littoral algae in coastal ecosystems, the effects of temperature increase on spring bloom dynamics of epilithic diatom communities were studied in two ways: (1) Communities were compared from sites receiving different amounts of cooling water discharge from a nuclear power plant. (2) Communities from the exceptionally warm spring of 1989 were compared with those from the same sites in the preceding normal years. The studies were carried out in and around the Forsmark Biotest Basin, an artificial waterbody that receives brackish cooling water from the Forsmark nuclear power plant on the Swedish east coast. Species composition and biomass data from 200 epilithic diatom samples taken in the period January-May from 1983 to 1989 were analysed. Multiple regression analysis was used to show the responses of diatom cover, community diversity and abundances of individual taxa to water temperature and other environmental factors. Constrained ordination (CCA) was used to display the relationship of overall community composition to environment. Increased water temperature resulted in higher biomass through a chain of ecological effects. Strong reduction of ice cover was crucial in this chain, resulting in reduced loss of diatom cells by reduced abrading and higher primary production by higher availability of light, nutrients and substrate. The conclusion is that large blooms of fast-growing epilithic diatoms in large colonies can occupy the niche that emerges when the ice-free season is prolonged in the northern Baltic Sea and areas similar in salinity and climatic conditions. Dramatic species shifts may only be expected if the winter ice cover is totally absent.     

Successional dynamics of the phytoplankton in the lower part of the river Ebro

The temporal and spatial dynamics of phytoplankton have beenstudied in four sites located along the last 60 km of the riverEbro, over a period of 1 year. Diatoms and green algae werethe most abundant groups; blue-green algae were frequent onlyin autumn. Asterionella formosa dominated the winter phytoplanktonassemblages. In autumn, spring and early summer centric diatomswere dominant: Aulacoseira granulata (Ehr.) Simonsen in autunm;Cyclotella sp. p1., Skeletonema potamos (Weber) Hasle and StephanodisciLssp. p1. in spring. A great abundance of green algae was observedduring the summer, mainly in the lower sites. In the sites closerto the mouth, the spring maximum of centric diatoms extendedto the summer. Mainly in the downstream sites, a remarkablegrowth of Acrinocyclus normanii f. subsalsa (Juhl.-Daunf.) Hustedtand Stephanodiscus hantzschii f tenuis (Hust.) Hak. & Stoerm.was added to green algae in the late summer. As has been investigatedthrough a principal component analysis, the phytoplankton temporalsuccession and longitudinal differences between the sites maybe affected by the variations in flow and the increase of waterconductivity downstream; both factors seem to act together.The river is rather homogeneous with respect to the phytoplanktonassemblages during the winter and spring months, and from latespring to the following autumn, differences greatly increaseboth in time and downstream.     

Seasonal distribution and fatty acid composition of littoral microalgae in the Yenisei River

We studied fatty acid (FA) composition of littoral microalgae in the fast-flowing oligotrophic river, the Yenisei, Siberia, monthly for 3 years. Seasonal dynamics of species composition had similar patterns in all the studied years. In springs, a pronounced dominance of filamentous green algae occurred, in summer and autumn diatoms were abundant, and in late autumn and winter epilithic biofilms consisted primarily of cyanobacteria and detritus. In general, FA composition of the algal periphytic community was dominated by 16:0, 16:1ω7, 20:5ω3, 14:0, and 18:3ω3 throughout the studied period. Several groups of FAs, which had peculiar seasonal dynamics, were differentiated by statistical analysis based on a method of correlation graphs. The seasonal changes in FA composition could be partly explained by the seasonal succession of species composition of the community. Besides, we found that populations of both diatom and green algae grown in summer at a higher water temperature were lower in polyunsaturated fatty acids than those in spring, at a lower temperature. Hence, we suppose that the regular seasonal dynamics of FA composition of the studied littoral microalgae was driven both by changes in species composition and by temperature adaptations of the algal populations. The highest content of essential polyunsaturated FAs, eicosapentaenoic and docosahexaenoic acids, in the spring “psychrophilic” populations of diatoms could make them of the higher nutritive value for zoobenthic primary consumers.     

典型红树林生态系统藻类多样性及其在生态过程中的作用

藻类是红树林生态系统重要的生物类群, 根据生态习性可分为浮游植物、底栖微藻和大型藻类三个生态类群, 它们在红树林生态系统生物多样性、初级生产、元素循环等方面起着重要作用。但在红树林生态系统中, 关注重点多集中在红树植物和动物, 对其中的藻类重视不够, 且多数研究集中在近20年以及亚洲的红树林区。事实上, 红树林生态系统藻类非常丰富, 其多样性研究有助于深入揭示红树林生态系统的结构与功能。本文介绍了红树林生态系统藻类的组成类群及其重要性, 重点对红树林区浮游植物、底栖硅藻和大型海藻的种类组成、地理分布及其与初级生产力、水质污染、元素循环、碳库形成等生态过程中的作用的研究动态和进展等进行了总结。根据已有研究, 红树林区浮游植物和底栖硅藻的种类数一般为几十到上百种, 其中硅藻在种类和数量上都占绝对优势, 它们是重要的初级生产者、饵料生物和水质污染指示生物; 红树林区底栖大型藻类主要由红藻、绿藻、褐藻、蓝藻组成, 绿藻的种类较多, 红藻在数量上占优势; 藻类是红树林湿地碳库的重要贡献者, 在红树林湿地生态系统碳汇和碳循环中起重要作用。红树林生态系统是个高度动态和异质的系统, 今后应加强红树林藻类多样性的长周期、大尺度变化及不同生境藻类的综合研究, 关注大陆径流和潮汐对藻类多样性和蓝碳的影响, 借助沉积物藻类记录, 探明红树林区藻类的长周期变化, 反演气候变化和人类活动对红树林生态系统的影响过程和机制。     

扎龙湿地硅藻植物群落季节变化及其对环境的响应

扎龙湿地位于黑龙江省西部、松嫩平原乌裕尔河下游,是我国北方同纬度地区最完整的湿地。于2012年春、夏、秋3季,对扎龙湿地6个代表性区域进行硅藻标本采集,经观察鉴定,发现硅藻植物140个分类单位,包括121种19变种,隶属于2纲6目9科30属。羽纹纲物种较丰富,占总种类数的95%。硅藻植物群落呈现明显的季节演替,秋季硅藻种类丰富度及相对丰度明显高于春、夏两季,优势种多以淡水、半咸水、喜弱碱的种类为主,优势种与水体的盐度和酸碱度存在一定的响应关系。应用典范对应分析(Canonical Correspondence Analysis,CCA)探讨硅藻植物群落变化与环境因子之间的关系。CCA结果显示在扎龙湿地中,水温、电导率、pH、溶解氧是影响硅藻群落结构变化的主要因素,此外总氮、总磷也是硅藻群落季节演替的重要驱动因子。结合硅藻植物多样性指数和硅藻商对扎龙湿地水质进行综合评价,结果显示扎龙湿地整体为中-寡污带水体,部分水域水质较清洁,少数样点受人为因素影响,呈轻污染。     

氮、磷对热带浅水湖泊惠州西湖蓝藻的控制

湖泊富营养化常导致蓝藻生物量的增加,水质恶化.于2011年2月至12月对热带浅水湖泊惠州西湖六个湖区的蓝藻群落结构进行研究,以了解其时空变化特征及主要影响因素.结果表明,以沉水植物为优势的元妙观湖区与南南湖蓝藻无明显的优势种;平湖蓝藻优势种为银灰平裂藻(Merismopedia glauca)和湖丝藻(Limnothrix sp.),南丰湖、北丰湖和北南湖的主要优势种均为银灰平裂藻(Merismopedia glauca).平湖、南丰湖、北丰湖和北南湖蓝藻丰度及生物量存在显著的季节变化.相关分析显示惠州西湖夏季蓝藻生物量受氮、磷盐控制.冬季温度的影响,蓝藻生物量与氮、磷的相关性不显著.     

Mixed populations of marine microalgae in continuous culture: Factors affecting species dominance and biomass productivity

Marine microalgae were grown in multispecies continuous cultures. Under carbon dioxide limitation, blue-green algae dominated. Under nitrate and light limitation, species dominance depended on the initial conditions. When the inoculum consisted primarily of blue-green algae with smaller amounts of other species, blue-green algae and pennate diatoms dominated. When the inoculum consisted of equal amounts of all species, green flagellates and pennate diatoms dominated. Green flagellates and blue-green algae were incompatible and never shared dominance. When nutrient limitations were overcome, the productivity of seawater was increased 100-fold before light limitation occurred. The productivity could be further increased by reducing photorespiration in the culture. The dilution rates studied (0.1, 0.2, and 0.4 day(-1)) had no effect on species dominance, nor did the higher dilution rates select for smaller cells. The maximum productivity occurred at a dilution rate of 0.2 day(-1). Temperature had the greatest effect on species dominance, with green flagellates, pennate diatoms, and blue-green algae dominating at 20 degrees C and only blue-green algae dominating at 35 degrees C. The productivity at 35 degrees C was lower than that at 20 degrees C because of the lower solubility of carbon dioxide at higher temperatures. At 10% salinity, green flagellates and pennate diatoms dominated. The productivity at this salinity was 50% that obtained at the salinity of seawater (3.5%). At 25% salinity, only the green flagellate, Dunaliella salina, survived at a productivity of 1% that obtained at the salinity of seawater.     

Winter phytoplankton communities in different depths of three mesotrophic lakes (Łęczna-Włodawa Lakeland, Eastern Poland)

Phytoplankton samples were collected from three mesotrophic lakes: Piaseczno, Rogóźno and Krasne during winter seasons (from January to March). The samples were analyzed for species analysis and abundance of planktonic algae in relation to different depths of water column (0–7 m). Selected water physical-chemical parameters were also measured. Abundance of phytoplankton depended strongly on the thickness of snow and ice cover or mixing conditions. The maximal phytoplankton total number reached about 5 × 10⁶ ind. L⁻¹ beneath the clear ice in the Krasne Lake, minimal numbers were recorded under the thick snow and ice layers in the Piaseczno Lake (2 × 10³ ind. L⁻¹). The winter phytoplankton communities were dominated by flagellates principally cryptomonads (Cryptomonas spp. Rhodomonas minuta), euglenophytes (Trachelomonas volvocina, T. volvocinopsis), dinoflagellates (Peridinium bipes, Gymnodinium helveticum) and chrysophytes (Mallomonas elongata, M. akrokomos, Dinobryon sociale) or non-motile small species of blue-green algae (e.g. Rhabdoderma lineare, Limnothrix redekei), diatoms (Stephanodiscus spp., Asterionella formosa), and green algae (e.g. Scenedesmus spp., Monoraphidium spp.). Phytoplankton abundance and structure showed differentiation during the winter season and along the water column as well.     

Selective effects of phytoplankton entrainment at the Surry Power Plant,James River,Virginia

Loss of cryptophyte cells entrained in the Surry Power Plant cooling water was significantly correlated with discharge water temperature in the range 27.2–37.5 °C. Entrained Skeletonema costatum and benthic diatom populations experienced losses of 25–80% in the summer, but correlations between % loss and discharge temperature were insignificant. Cropping by benthic filter feeders in the intake and discharge canals could account for the summer removal of diatoms. Shortening of entrained S. costatum chains was detected in both winter and summer, indicating a mechanical effect of turbulence.Benthic diatoms were vulnerable to entrainment only during daylight hours, when they migrated to the sediment surface at low tide. Skeletonema costatum was most vulnerable in the summer, when elevated salinities permitted it to range upstream to the intake area. Cryptophyte populations peaked in the summer when entrainment loss was greatest.The composition of the entrained phytoplankton community was altered by the species specific interactions of factors affecting vulnerability and entrainment loss. At Surry the discharged cooling water mixes rapidly with the main stem James River, and the selective effects of entrainment are not detectable in phytoplankton samples taken beyond the immediate discharge zone. More persistent modifications of the phytoplankton could be expected at sites where power plants discharge into creeks or embayments.Contribution No. 1106, Virginia Institute of Marine Science.Contribution No. 1106, Virginia Institute of Marine Science.     

Dynamics of phytoplankton growth in the Waikato River,North Island,New Zealand

The Waikato River (latitude 38°S, longitude 176°E, North Island, New Zealand) is overwhelming y dominated by diatoms (mainly Melosira species) while blue-green and green algae are of minor importance. Both laboratory and in situ nutrient enrichment experiments showed enhanced growth of natural and index blue-green and green algae by addition of phosphate and nitrate. These algae were also shown to require higher temperature and light intensity than the diatoms. On the other hand, Waikato River with its higher silica content, moderate range of temperature and running water habitat was more favourable an environment for diatoms.