南水北调中线干渠两个水工构筑物对着生藻类群落的影响

在南水北调中线干渠两个水工构筑物沙河渡槽与穿黄工程渠段分别设置沙河渡槽上游明渠、沙河渡槽入口、沙河渡槽出口、穿黄工程入口、穿黄工程出口、穿黄工程下游明渠和穿黄工程下游沁河倒虹吸7个监测位点, 对着生藻类群落与水质指标进行了原位同步监测。结果表明: 监测位点的蓝藻优势种有鞘丝藻(Leptolyngbya sp.)、聚球藻(Synechococcus sp.)、眉藻(Calothrix sp.)、席藻(Phormidium sp.)、集胞藻(Synechocystis sp.)和拟色球藻(Chroococcidiopsis sp.)等; 真核藻类优势种有链带藻(Desmodesmus sp.)、土佐牧野藻(Makinoella sp.)、芒球藻(Radiococcus sp.)、盘星藻(Monactinus sp.)、卵囊藻(Oocystella sp.)、菱形藻(Nitzschia sp.)、针杆藻(Synedra sp.)和肘形藻(Ulnaria sp.)等。经过渡槽后藻类生物量下降50%, 藻类种类数下降16%; 经过穿黄工程后藻类生物量下降80%, 藻类种类数下降18%。经过沙河渡槽后, 真核藻类中链带藻(Desmodesmus sp.)相对丰度由26.4%增至77.4%, 针杆藻(Synedra sp.)相对丰度由10.4%降至0.4%, 肘形藻(Ulnaria sp.)相对丰度由2.3%降至0.4%; 经过穿黄工程后, 鞘丝藻(Leptolyngbya sp.)相对丰度由82.6%降至56.5%, 胶须藻(Rivularia sp.)相对丰度由6.2%增至61.8%。水工构筑物通过影响水流条件和水质改变微生境从而对着生藻类群落结构产生显著影响, 研究有助于深入了解着生藻类群落特点及水工构筑物对其具体影响。     

宁夏沙坡头地区藻类及其分布

通过野外采样,室内培养、观察、鉴定,研究了沙坡头地区藻类多样性和分布特点,并为当地藻类资源利用提出建议。研究发现沙坡头地区藻类植物共计40种(包括1变型),其中蓝藻17种,绿藻10种,硅藻9种,裸藻4种,全为普生种,陆地生境中种类最丰富。亚气及陆地生境中蓝藻在种类数(除灌溉林地结皮)、生物量方面占主导地位;贫瘠水体生境中硅藻占主要地位,营养较丰富水体中绿藻处于优势地位。另外,陆生生境中多以具鞘微鞘藻Microcoleus vaginatus为优势种,小席藻Phormidium tenue为主要种。     

南美白对虾精养塘浮游微藻动态研究

2006年4月30日～2006年8月31日,对舟山市马岙镇的旭旺无公害对虾精养基地水体的浮游微藻群落结构进行调查分析.结果表明:精养塘中共检出常见浮游微藻5门16种,其中蓝藻4种,绿藻5种,硅藻5种,裸藻1种,甲藻1种.主要蓝藻有微小平裂藻(Merismopedia tenuissima.)、小席藻(Phorimidium sp.)、螺旋藻(Spirulina sp.)等;常见绿藻有小球藻(Chlorella sp.)、衣藻(Chlamydomonas sp.)等;常见硅藻有舟形藻(Navicula sp.)、尖针杆藻(Synedra acus)等.养殖早期3门9种,蓝藻门与裸藻门的微藻未检查到,且浮游微藻细胞数量为0.8×10⁷cells·L^-1,香浓多样性指数平均为0.445.养殖后期4门12种,多甲藻未出现了,浮游微藻细胞数量为1.5×10⁷ cells·L^-1,香浓多样性指数平均为0.375.浮游藻类多样性指数总体表现为养殖前期高后期低的特征.     

浮游动物调控对浮游藻类的影响

浮游动物可以通过牧食作用来抑制浮游藻类的增长, 同时浮游动物排泄的营养盐又可以促进浮游藻类的增长,二者的强弱是浮游动物控制浮游藻类的关键。通过人为去除处理组水体中的浮游动物, 研究浮游动物生物量和群落结构的不同对富营养水体中浮游藻类的影响。研究结果显示处理组浮游动物总生物量低于空白组, 且缺乏大型枝角类溞属(Daphnia sp.); 去除浮游动物显著降低了水体中的总氮和总磷浓度以及浮游藻类生物量(叶绿素a), 同时增加了附着藻的生物量; 并且影响了浮游藻类群落结构: 对照组是空星藻(Coelastrum sp.)为优势种而处理组则为湖丝藻(Limnothrix sp.)和四集藻(Palmella sp.)。结果表明浮游动物排泄营养盐产生的上行效应大于牧食作用产生的下行效应。     

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。     

福建红树林区大型藻类的生态学研究

主要研究中国福建省红树林区大型藻类分布、优势种的生物量和林冠下藻种的垂直分布特点。结果表明:福建红树林区的大型藻类有24属42种,其中蓝藻8属15种、红藻3属7种、绿藻13属20种。优势种中鹧鸪菜(Caloglossa leprieurii)和节附链藻(Catenella impudica)的生物量在6月分别为2.22～8.44g/m~2 DW和2.69g/m~2 DW,在12月分别为0.15～0.20g/m~2 DW和2.12g/m~2 DW。红树林中树干上附着生长的大型藻类的垂直分布自下而上可分成6个带:1.无隔藻(Vaucheria sp.)带;2、节附链藻带;3.侧枝鹧鸪菜-混合卷枝藻(Caloglossa ogasawaraensis-Bostrychia mixta)带;4.鹧鸪菜带;5.硬毛藻-岸生根枝藻(Chaetomorpha macrotona-Rhizoclonium riparium)带;6.绿球藻(Chlorococcum sp.)带。     

南亚热带河流型水库浮游植物群落的季节变化：以广东飞来峡水库为例

于2003年4-12月调查了广东省飞来峡水库的水文、营养盐分布状况和浮游植物种类与数量,分析了浮游植物群落的种类及数量组成与动态特征,探讨了其动态变化的驱动因子。结果表明,飞来峡水库是一个典型的河流型大型水库,水力滞留时间短,年均值低于15 d;降雨量主要集中于夏季,最短水力滞留时间只有8 d。水温全年没有分层现象。丰水期营养盐和叶绿素a高于枯水期。浮游植物生物量低,细胞密度在21.7×103-808×103 cells L-1之间变化,没有超过106 cells L-1,叶绿素a的平均浓度为2μg L-1。浮游植物种类较多,4次采样共检到140种。种类组成上有较大变化,4月份有83种,以硅藻为主;7月和9月超过90种,以绿藻为主;12月有51种,蓝藻、绿藻和硅藻种类数量相当。优势种类的构成上与温带水库不同,硅藻仅在低水温时期为优势类群,而在丰水期则以蓝藻、绿藻和硅藻共同占优势。硅藻的主要优势种是变异直链藻(Melosira varians)、梅尼小环藻(Cyclotella menighiniana)和针杆藻(Synedra spp.)。绿藻种类组成季节变化较大,没有明显的优势种类。丰度相对较高的有美丽胶网藻(Dictyosphaerium pulchellum)、集星藻(Actinastrum hantzschii)和空球藻(Eudorina elegans)等。蓝藻的优势种以粘球藻(Gloeocapsa sp.)、优美平列藻(Merismopedia elegans)和伪鱼腥藻(Pseudoanabaena sp.)为主。与绿藻不同的是蓝藻的优势种在全年均可出现。隐藻只在水力滞留时间较长、温度较低的12月份占优势,主要优势种为啮蚀隐藻(Cryptomonas erosa)、尖尾蓝隐藻(Chroomonas acuta)。     

丹江口水库浮游植物时空动态及影响因素

2007年7月至2008年6月对丹江口水库浮游植物进行了为期一年的调查和分析,共采集到浮游植物8门、60属、110种及变种.种类组成以绿藻门、硅藻门和蓝藻门为主,其中绿藻门占优势,共计46种(42％),其次为硅藻35种(32％).藻类年平均密度为4.17×106 celVL,最高密度为6.10×107 cell/L,最低密度为5.16×103 cell/L.各季节浮游植物优势种差异显著,春季为一种颤藻(Oscillatoria sp.)和尖针杆藻(Synedra acus),夏秋两季为啮蚀隐藻(Cryptomonas erosa),冬季转为倪氏拟多甲藻(Peridiniopsis niei).空间分布上,丹江、汉江库区以及取水口3个区域浮游植物优势种为尖针杆藻,五青入库区则以倪氏拟多甲藻占优势.磷浓度是驱动丹江口水库藻类密度的主要影响因子.根据建库几十年来的对丹江口水库较为全面的4次调查资料,分析了丹江口水库的浮游植物群落演替及变化趋势.自1958年以来,50年间,整个水库浮游植物密度增加了16倍,水库富营养化程度有增加的趋势.种类组成由适应河流的固着型硅藻,经过硅藻-绿藻-蓝藻型逐渐发展为硅藻-甲藻-隐藻-蓝藻型.     

西湖湖西浮游与着生藻类季节变化及相互关系

2014年11月至2015年8月调查了西湖湖西沿岸带浮游藻类和不同基质(植物、石块和底泥)上着生藻类的群落结构及季节变化, 分析了着生丝状藻与浮游丝状藻的相互关系以及它们与环境因子的相关性, 探讨湖西生态修复过程中季节性暴发的丝状藻水华的原因。结果表明浮游藻类和植物、底泥、石头上着生藻类中均以硅藻门种类数(分别占52.5%、60.4%、86.7%和72.7%)最多, 蓝藻门(分别占10.1%、8.9%、6.7%和15.2%)和绿藻门(分别占26.3%、19.8%、5.6%和10.6%)次之, 其他门类相对较少, 浮游藻类与着生藻类优势种季节差异较大。附植丝状藻密度显著高于附泥和附石丝状藻, 且狐尾藻上着生丝状藻密度与浮游丝状藻密度呈显著正相关, 表明狐尾藻着生丝状藻可能是浮游丝状藻较重要的来源之一, 该结果可为西湖丝状藻水华的控制提供一些参考。相关性分析表明, 着生藻类和丝状藻与各理化因子(水深、透明度、溶解氧、水温、pH、TN、SRP、TP等)均无显著相关性。     

抚仙湖浮游植物群落结构、分布及其影响因子

云南抚仙湖是我国典型的高原深水湖泊,为揭示该湖浮游植物群落特征及其对生态系统变化的响应,2005年6～7月对浮游植物及环境因子进行了调查.调查期间共采集浮游植物80种,隶属于7门32科56属,以绿藻、蓝藻和硅藻为主,种类数绿藻(46.0%)＞蓝藻门(25.0%)＞硅藻门(15.0%),密度绿藻(61.6%)＞硅藻(16.1%)＞蓝藻(9.1%).群落平均密度为87.58 ×104 ind./L, 转板藻(Mougeotia sp.)占绝对优势,其相对密度为35.9%.在水平分布上,浮游植物平均密度北区大于南区(P＜0.05),沿岸区大于湖心区(P＜0.01).在垂直分布上,浮游植物分层明显,主要分布在0～30 m水层,不同水层绿藻均占绝对优势.环境分析表明:抚仙湖浮游植物密度水平分布主要受营养盐的影响,而垂直分布主要受物理因子的影响.不同时期的调查结果比较表明,抚仙湖浮游植物种类数和密度呈增长趋势,与水体营养水平升高有关.20世纪90年代中期以来,大型丝状藻类转板藻发展成为绝对优势种,与其较强的竞争优势及太湖新银鱼摄食引发的下行效应有关.     

A COMPARISON OF PERIPHYTIC ALGAL BIOMASS AND COMMUNITY STRUCTURE ON SCIRPUS VALIDUS AND ON A MORPHOLOGICALLY SIMILAR ARTIFICIAL SUBSTRATUM1

Chemically inert, cylindrical rods positioned in the littoral of two eutrophic Alberta lakes supported higher periphytic algal biomass (measured as total chlorophyll a) than nearby morphologically similar culms of Scirpus validus Vahl. during most of the summer. Upon initiation of macrophyte senescence, biomass on the two substrata became more similar. Experiments were conducted to investigate the basis for these observations. Whole extracts of intact vegetative Scirpus culms had no effect on periphyton photosynthesis, suggesting that the natural substrata do not produce water-soluble allelochemicals. Various modifications of the rod surfaces (roughening, wax coating, wax color) were used to test whether surficial properties of Scirpus culms influenced periphyton accumulation. Roughened rods supported levels of biomass similar to those of smooth rods, and both substrata developed structurally complex periphyton communities. Rods covered with paraffin wax had periphyton communities that were lower in biomass and structurally more simple than those on un-coated rods or on Scirpus culms. Coloring of the wax coating had no consistent effect on periphyton accumulation. We hypothesize that the hydrophobic cuticle on actively growing Scirpus culms retards the development of precursors for attachment by periphytic algae. Upon senescence of the culm and loss of epidermal integrity, colonization of culm surfaces by periphytic algae may occur in a manner similar to that on artificial substrata.     

Factors determining periphytic algae succession in a tropical hypereutrophic reservoir

The objectives of this study were to evaluate the effect of cyanobacterial blooms on periphyton algal succession and to identify the factors determining community dynamics in a tropical hypereutrophic reservoir. A variety of factors affecting periphytic community structure were identified at two different sites with domestic sewage and spring water inflows and two climatic periods. Microscope glass slides were used to assess periphyton growth. Sampling was carried out at short regular intervals (3–5 days) over 30 days. Climatic periods were limnologically distinct. The rainy period was characterized by an intense cyanobacterial bloom and the dry period by a less intense bloom. Periphyton biomass and growth tended to increase with colonization time during the dry period. Cyanobacteria and Bacillariophyceae were the most representative groups in the rainy period whereas Bacillariophyceae was dominant in the dry period. Community species had successional patterns in both climatic periods. The successional trajectory for sites 1 (domestic sewage) and 2 (spring water) was different in the dry period but similar in the rainy period. We concluded that the community structure over 30 days of colonization under hypereutrophic conditions was primarily determined by seasonal scale (bloom intensity), followed by successional scale (autogenic), and, finally, by the local scale (spring water and sewage inflow). Positive periphyton biological response (higher biomass and algal growth, dominance of diatoms, Cyanobacteria reduction) during small variations of bloom intensity may indicate rapid re-establishment of the community during recovery of the ecosystem.     

Littoral diatoms as indicators for the eutrophication of shallow lakes

The littoral zone of shallow water bodies in the Czech Republic has been studied quite consistently at several fishponds. The use of algae, especially diatoms, for the monitoring of the state of lotic freshwater also has a long tradition. The main objective of the presented paper is to validate the feasibility of the use of littoral periphyton comunities for the biomonitoring of standing waters. At the investigated sites, littoral periphytic diatoms were studied together with selected enviromental variables (pH, conductivity, nutrients – especially total phosphorus) on three types of natural substrates (epilithon, epiphyton, epipelon). The evaluation of the diatom community was performed on the basis of the checklists of algal indicator species published by authors from the Czech Republic, Austria and the Netherlands. The data were subjected to statistical software NCCS 2000 (GLM Anova and ``Ward's minimum'' variance cluster analysis). Littoral periphytic diatoms appear to be good indicators of the fishpond water quality. The selected substrates show non-significant differences therefore the average values from all substrates were used. The best indicatory system for evaluation of Czech fishponds was van Dam's index.

     

Periphytic and drifting microalgae in a tributary stream of Øvre Heimdalsvatn

Samples of drifting and periphytic microalgae were collected during 1972 from a fast-flowing, stony stream (Brurskardsbekken) in the Jotunheimen mountain area, central southern Norway. The predominant algal groups in the drift and the periphyton were diatoms and green algae, while only a few species were recorded in both communities. A considerable number of species from Chrysophyceae, Cryptophyceae and other algal classes were also recorded in the drift samples. The species composition was in good agreement with microalgal communities earlier described from mountain areas in Scandinavia, although species which probably are new to Norway, were also recorded. A quantitatively important fraction of planktonic species in the drift is interpreted as a contribution from lacustrine habitats in the watercourse. A general change in the periphyton during the summer, from green algae to diatoms, was observed, Altitudinal differences in the periphyton included a delayed green algal maximum at higher altitudes compared to lower. In the zone around the upper birch limit, a transition in species composition as one goes up stream, described in other investigations, was not observed.     

Experimental Analysis of Grazing by the Mayfly Meridialaris chiloeensis on Different Successional Stages of Stream Periphyton

In this study we determined grazing effects of the South Andean endemic mayfly Meridialaris chiloeensis on periphyton at different stages of successional development. Grazing effects were studied through a two‐factor experimental design (colonization stages X grazer density) in a stream‐side channel in spring and winter. Our results showed an absence of proportionality between grazer density and periphyton decline in response to grazers at low and intermediate levels of periphytic biomass; however, when periphyton biomass was high a direct inverse relationship was observed between post‐grazing biomass and grazer density. The relationship between periphytic algae (chlorophyll a concentration) and periphyton (total periphytic ash‐free dry mass) (C/OM index) was used as an estimation of the autotrophic fraction in the total periphyton matrix. Grazing did not alter the C/OM index indicating that both autotrophic and heterotrophic fractions of the periphyton components were reduced in the same proportion. Ordination of samples using the relative abundance of diatom species showed that herbivore effect was less evident at intermediate and late stage of colonization than at early one. These results support the statement that the outcome of the herbivore‐periphyton interaction may depend on the successional stage of the periphyton community. In spring Fragilaria pinnata relative abundance, on the basis of cell counts, was reduced by grazing and Nitzschia palea was enhanced. In the winter experiment, grazing decreased Achnanthes minutissima relative abundance. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Role of sediment and internal loading of phosphorus in shallow lakes

Current velocity is a pervasive feature of lotic systems, yet this defining environmental variable is rarely examined as a factor for regulating stream herbivory. To investigate how current modifies herbivory in the upper Colorado River, U.S.A., loops of electrified fencing wire were used to reduce in situ grazer densities on 30 × 30 cm tile substrates. After 45 d, electrified tiles had significantly fewer grazers (P = 0.03) and >2X more algal biomass than controls (P = 0.0002). Reduced grazing on electrified tiles yielded periphytic assemblages having more diatoms and chlorophytes, as well as greater algal species richness. Current velocity effects alone did not significantly regulate algal abundance; however, the interaction between current velocity and grazer exclusion resulted in more algae in slow vs. fast current (P = 0.02). Grazer abundances were similar between fast and slow current velocities, suggesting that grazers in the Colorado River differ in their ability to regulate algae across the current velocity gradient. Our results indicate that stream current-mediated herbivory in streams may be more important than is generally recognized.     

Vertical distribution of attached algae in shallow fishponds of different trophic status

Spring and summer vertical distributions of attached algae were studied on artificial substrates (glass cover slips) in shallow fishponds of different trophic status. Differences were found in colonization process between two fishponds, two seasons and between two sites at each fishpond (central part, fishpond shore). Oligotrophic fishpond U třech krátkych can be characterized by better light conditions and lower temperatures. While equal vertical distribution of periphytic algae was observed at oligotrophic site, their relative cover decreased continuously in spring and strongly in summer with the increasing depth at eutrophic site. Oligotrophic fishpond can be characterized by very slow colonization rate and increasing abundance of Chrysophyceae. On the other hand Cyanobacteria were more frequent in eutrophic fishpond where periphyton displayed high colonization rate. Diatom species richness was the highest at oligotrophic site during spring experiments. The sites near the fishpond shore compared to sites in the central part of the fishpond can be characterized by higher rate of colonization, higher periphyton relative cover, lower proportion of Chrysophyceae and higher proportions of diatoms and cyanophytes indicating probably higher trophic level.     

Does light intensity modify the effect mayfly grazers have on periphyton?

1. A factorial experiment was conducted in artificial outdoor streams to quantify the effects of irradiance (two levels) and two mayfly grazers (four densities of each) on periphytic community structure. The mayflies were Ecdyonurus venosus (Heptageniidae), a grazer using brushing mouthparts, and Baetis spp. (Baetidae) a grazer which uses mandibles and maxilla to scrape and gather periphyton. The experiment ran for 16 days. 2. Grazer densities in channels approximated those existing in a shoreline habitat in the River Sihl, Switzerland. Light treatments were natural (daily mean = 810 μmol m^–2 s^–1) and shaded (daily mean = 286 μmol m^–2 s^–1). 3. Higher irradiance increased total algal abundance by a factor of 4. Algae most affected were prostrate/motile and erect diatoms, filamentous chlorophytes and Hydrurus foetidus. 4. Both species of mayfly reduced periphytic and algal biomass. Mayfly–mayfly interactions, however, were associated with statistical increases in algal biovolume and chlorophyll-a content, indicating that the two grazers may have interfered with one another as their densities increased. The mayfly–mayfly interaction did not influence periphytic ash-free dry mass (AFDM). Light modified the influence of Ecdyonurus such that this mayfly produced greater reductions in algal biovolume under high irradiance. 5. Despite efforts to exclude other grazers, chironomids colonized experimental channels. Chironomid biomass was approximately eight times less than mayflies across treatments and was positively correlated with all measures of periphytic abundance, suggesting that these grazers were responding to periphyton rather than controlling it. Chironomids were also associated with an increase in the abundance of diatoms having a prostrate/motile physiognomy. The only physiognomy to show a negative relationship with chironomid biomass was the thallus type, a form which comprised less than 1% of the algal biovolume across channels. 6. Ecdyonurus and Baetis had distinct influences on algal physiognomy. Ecdyonurus, for example, reduced adnate, stalked and Achnanthes-type physiognomies, but was associated with a significant increase in the abundance of filamentous chlorophytes (primarily Ulothrix sp.). Baetis reduced erect, Achnanthes-type and thallus physiognomies. Neither mayfly influenced the abundance of prostrate/motile diatoms; a physiognomy that comprised 21% of the algae in channels. 7. Light and mayfly interactions affected algal community structure. The interaction of Ecdyonurus with light had a negative effect on erect diatoms, filamentous chlorophytes and the thallus physiognomy, but a positive effect on stalked and Achnanthes-type physiognomies. Baetis interacting with light had a positive effect on adnate diatoms. 8. Although both mayfly taxa influenced periphytic community structure, physiognomy was not a good predictor of algal susceptibility to grazing. The type of substratum to which an alga is attached (detritus or algal filaments vs hard surfaces) and location within the periphytic matrix may be better indicators of vulnerability to grazing than physiognomy.     

EVIDENCE OF DARK AVOIDANCE BY PHOTOTROPHIC PERIPHYTIC DIATOMS IN LOTIC SYSTEMS1

Short-term (24–48 h) colonization dynamics of periphytic diatoms on artificial (styrofoam) substrata were examined using fast-flushing, continuous-flow troughs located on the North Thompson River, British Columbia. Two parallel troughs, one exposed to natural light and the other completely darkened, showed significant differences in periphyton biomass, chlorophyll a, and algal taxonomic composition with 24 h. Experiments which commenced at the onset of natural darkness demonstrated that rates of algal immigration during the night were the same in both troughs. Within 2–3 h of sunrise, however, certain diatom species (most notably Hannaea arcus (Ehr.) Pair, and Diatoma tenue Ag.) selectively emigrated from the artificially darkened trough but remained in the trough exposed to natural light. More closely adhering species such as Achnanthes minutissima Kütz, also showed significant emigration from the darkened trough after light deprivation for two photoperiods. Data from adhesion, emigration, and sinking rate experiments indicate that differential egress of cells from the darkened versus the lighted environments is the result of cellular regulation of buoyancy or form resistance.