19 Periphytic algae as bioindicators of nitrogen inputs in lakes

Increased nitrogen levels has been shown to be a problem in Southern New Jersey lakes, with anthropogenic loadings being the most serious concern (Aber, 1992). It has been suggested that biomass, diversity, and community structure of periphytic algae are good biotic indicators for monitoring water quality and nutrient enrichment in fresh water lakes. (Biggs, 1989). Since, for algae and many other aquatic organisms, nitrogen is one of the most important factors for growth, a good correlation it is expected between nitrogen loading and algal growth. In this bench-scale microcosm study the periphytic community was analyzed using chlorophyll a, dry-ash weight biomass and cell counts, as well as the diversity and community structure for a six-month period, in three tanks with different nitrogen levels (control=non-detectable; low and high). Physical (T/DO/pH) and chemical (nutrients) parameters were measured monthly. Biological parameters were compared with the different nitrogen loading using correlation analysis to show whether nitrogen is a factor in the over-enrichment of New Jersey lakes. To compare the bench-scale microcosm study with the natural settings periphytic algae from two Southern New Jersey lakes, Oswego Lake (no nitrogen) and Oakford Lake (high nitrogen), were also collected during fall of 2002 to summer of 2003.     

Spatial and seasonal changes of net plankton and zoobenthos in Lake Tonle Sap, Cambodia

To clarify spatial and seasonal differences in net plankton and zoobenthos in Lake Tonle Sap, Cambodia, quantitative surveys were carried out at 14 stations in the north and south basins in high- and low-water seasons during 2003–2005. In the phytoplankton communities, a diatom Aulacoseira granulata dominated throughout the lake in the high-water seasons, while blue-green algae, mostly composed of Microcystis, surpassed other algae in the low-water season when the lake water was very turbid and the Secchi disk readings were only a few centimeters. In the low-water seasons, a bloom of floating blue-green algae occurred everywhere, especially prominent in the coastal areas. Protozoans and rotifers dominated the zooplankton communities. In the open-water stations, diversity was higher in high-water seasons in phytoplankton, while it was not significantly different between seasons in zooplankton. Composition of plankton communities in Lake Tonle Sap appears to have changed little since the 1950s, at least in phytoplankton, while the phytoplankton density appears to be higher in the present study. Among the macrozoobenthos, mollusks, oligochaetes and chironomids dominated in density, and mollusks exceeded others in biomass in both basins and seasons. The total densities of macrozobenthos were not high, being fewer than 1,300 m⁻² throughout the stations and seasons. Possible reasons for the low zoobenthos abundance in the lake may include high predation pressures by benthivorous fish or unfavorable unstable and flocculant substrates.     

Quantifying the impact of periphytic algae on nutrient availability for phytoplankton

SUMMARY.

• 1 Recent laboratory studies demonstrate that periphytic algae growing on the sediment surface reduce nutrient availability in the overlying water. Consequently, periphytic algae may competitively reduce growth of phytoplankton.
• 2 The aim of this study was to quantify the competitive impact of sediment-attached periphytic algae on phytoplankton in the presence of all other factors simultaneously affecting nutrient dynamics in natural systems.
• 3 In enclosure experiments, performed in three lakes of different productivity, the periphytic algal biomass was manipulated. When compared to enclosures with high biomass of periphytic algae, those with reduced biomass showed an increase in total phosphorus concentration in the water of 32–44%. Extrapolation of the experimental results to whole lakes predicts an increase in original total phosphorus concentration of between 1.5% and 8.0%. According to existing regressions between total phosphorus and phytoplankton chlorophyll, the potential increase in original phytoplankton biomass will be between 2.5% and 12.6%.
• 4 With respect to the shallow parts of lakes, my results support the conclusions revealed from laboratory studies that periphytic algae have a significant impact on the phosphorus concentration in the overlying water. However, when considering whole-lake dynamics, the competitive impact of periphytic algae on phytoplankton biomass development is probably of minor importance.
• 5 Rather, the main competitive advantage of growing on the sediment surface, compared to in the water, may be the exclusive access to nutrients in the sediment.

     

金沙江上段浮游藻类和着生藻类群落格局及其与环境因子的关系比较研究

比较河流浮游藻类和着生藻类群落的时空格局及其与环境因子关系的差异,有助于了解两类藻的区别与联系。然而,目前这方面的研究还不多。基于2019年秋季和2020年夏季金沙江上段干流17个样点藻类及水体理化指标的调查数据,分析了不同季节浮游藻类和着生藻类群落结构及其主要环境驱动因子,比较了两类藻的多样性格局及其与环境关系的异同。结果发现,调查河段的浮游藻类和着生藻类均以硅藻为主,其中浮游藻类以极小曲壳藻(Achnanthes minutissima)、钝脆杆藻(Fragilaria capucina)、适中舟形藻(Navicula accomoda)为主要优势种,着生藻类以极小曲壳藻(Achnanthes minutissima)、扁圆卵形藻(Cocconeis placentula)、橄榄绿色异极藻(Gomphonema olivaceum)为主要优势种。浮游藻类和着生藻类秋季平均密度分别为:2.41×10~5个/L、9.43×10~3个/cm~2,均明显高于夏季的平均密度(4.84×10~4个/L、4.84×10~3个/cm~2)。两类藻的群落格局表现出明显的季节变化,但只有着生藻分类单元...     

Macroinvertebrates of flooded trees in the man-made Volta Lake (Ghana) with special reference to the burrowing Mayfly Povilla adusta Navas

Summary The species composition of periphytic macroinvertebrates on and in flooded trees differs at different localities on the Volta Lake. The main differences concern chironomid and trichopteran larvae. The reasons for this lie in the different exposure of trees to wave action, in the availability of soft wood and bark as a substrate, and in the distance of trees off-shore. All these factors determine the intensity of growth of the periphytic algae. The growth of the periphytic fauna will also be influenced by the density of phytoplankton on which it feeds. Other factors, such as oxygen concentration and the turbidity of the water, are also likely to affect the productivity of the whole community.The abundance of Povilla nymphs, the most common organism in trees, seems to depend on the type of the substrate. The bark of trees is exploited more than the wood, and trees with harder wood are less attacked than those with soft wood. Macroscopically, the male nymphs can be distinguished from female nymphs from a length of 6.0 mm, and they start to emerge when 9.0 mm long. Females emerge from 14.0 mm length. Nymphs tend to be heavier in dense populations. The difference in the weight of nymphs may be due to differences in availability of food.Nymphs of Povilla were found to feed both on solitary and attached periphytic algae, together with detritus and planktonic algae. Because of the great abundance of Povilla the nymphs of this species are of great importance in the conversion of algae into animal protein, being themselves heavily exploited by fish.No lunar periodicity, such as occurs on Lake Victoria, was found, and Povilla in the Volta Lake seems to emerge continuously.     

Environmental influences on the qualitative and quantitative composition of phytoplankton and zooplankton in North African coastal lagoons

Within the framework of the international research project MELMARINA, seasonal dynamics of plankton communities in three North African coastal lagoons (Merja Zerga, Ghar El Melh, and Lake Manzala) were investigated. The sampling period extended from July 2003 to September 2004 with the aim of evaluating hydrological and other influences on the structure, composition and space-time development of these communities in each lagoon. Phytoplankton in Merja Zerga showed a quasi-permanent predominance of marine diatoms in the open sea station and in the marine inlet channel. Dinoflagellates were abundant in summer and early autumn in the marine inlet and extended into the central lagoon station. In Ghar El Melh, marine species (especially diatoms and dinoflagellates) dominated despite occasional winter inflows of freshwater. In Lake Manzala, freshwater species generally predominated and the planktonic communities were comparatively very diverse. Chlorophyceae contributed 39% of the total species recorded and diatoms and cyanophyceans were also common; the Dinophyceae, Euglenophyceae, Chrysophyceae and Cryptophyceae less so. Zooplankton communities in both Ghar El Melh and Merja Zerga were dominated by marine copepods. Rotifera, Copepoda, Ostracoda, and Cladocera were recorded in both lagoons as were meroplanktonic larvae of Polychaeta, Cirripedia, Mysidacea and Gastropoda and free living nematodes. Ghar El Melh was the more productive of these two lagoons with spring and early summer being the productive seasons. Zooplankton communities in Lake Manzala were generally dominated by rotifers and highest zooplankton abundances occurred in April (2003). Sampling stations near the marine inlets showed the highest diversity and the zooplankton communities showed considerable spatial variation within this large lagoon. The three lagoons represent very different water bodies contrasted strongly in terms of tidal effects and freshwater availability. Yet, there are some similarities in ecosystem structure. Space-time development of the plankton communities was similar especially in Merja Zerga and Ghar El Melh. Species abundances and specific diversities indicated that seasonal changes in salinity and nutrient concentrations were the main influential factors. Lake Manzala was the most productive lagoon and all the three sites supported toxic algal species. Relatively low plankton biomass in Merja Zerga and Ghar El Melh probably resulted from a combination of factors including highly episodic nutrient inputs, light suppression (by turbidity) and nutrient competition with benthic algae. Water quality variables were largely driven by the hydrological regime specific to each lagoon. Nutrient enrichment and, particularly for Lake Manzala, sea level rise threaten the sustainability of the planktonic ecosystems in all three lagoons. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users. Guest editors: J. R. Thompson & R. J. Flower Hydro-ecological Monitoring and Modelling of North African Coastal Lagoons     

The effect of wind exposure and filamentous algae on the distribution of surf zone macroinvertebrates in Lake Esrom,Denmark

Distribution and composition of the epilithic macroinvertebrate fauna was studied on 21 different sites situated in the surf zone of Lake Esrom. A relative degree-of-exposure (windinduced wave activity) was calculated for each station from the specific number of wind days, wind velocity and a measured wind fetch. Macroinvertebrate abundance averaged 20 200 ind. m^–2 stone bottom, and was composed primarily of six taxa (70% of the mean densities). The distribution patterns of the 48 most common taxa were compared to exposure, the amount of filamentous algae and shore slope, by regression, cluster analysis and ordination analysis (PCA and RDA). The abundance of 25 taxa was significantly correlated to the amount of filamentous algae, and a protectional effect of algae growth was suggested for the exposed sites. Seventeen taxa showed significant difference in abundance between sheltered western stations and exposed eastern stations. Stations with a gentle slope were characterised by sand covered stones and a fauna that qualitatively was similar to the fauna at greater depth in the littoral. Redundancy analysis (RDA) showed filamentous algae and slope to be the most important factors controlling the species distribution, whereas the gradient of exposure in Lake Esrom was too short to explain the species tolerance range.     

基于周丛藻类群落结构的新疆额尔齐斯河生态健康评价

周丛藻类对水环境变化较为敏感,可迅速而灵敏的反映水质健康状况。本研究于2019年对额尔齐斯河周丛藻类群落结构和水环境特征进行了系统调查,并运用周丛藻类生物完整性指数(Periphytic algae index of biotic integrity, P-IBI)对生态健康进行了评价。结果表明:额尔齐斯河周丛藻类有6门41属102种,以硅藻门为主。周丛藻类密度和生物量的时间变化趋势为:9月>7月>5月,空间分布趋势为中下游>上游、支流>干流。主成分分析(PCA)与典范对应分析(CCA)显示,影响周丛藻类群落结构的主要环境因子有水温、溶解氧、高锰酸盐指数、氨氮、硝酸盐氮、pH、悬浮物,不同月份的环境影响因素有所差异。额尔齐斯河周丛藻类多样性指数(H′)、丰富度指数(D)、Pielou均匀度指数(J)的平均值分别为3.52、3.02、0.75,显示额尔齐斯河流域整体水质为寡污或无污。P-IBI分析结果显示:5个采样点为健康状态,1个采样点为亚健康状态,3个采样点为一般状况,1个采样点极差,表明额尔齐斯河整体生态健康状况趋于良好。本研究可为额尔齐斯河的水环境监测提供...     

72 An examination of the periphytic algae in the sheyenne river, north dakota, usa, and the factors influence the community structure

The Sheyenne River is a third order stream in central and eastern North Dakota. The algae in this river had not been previously studied. For this study, periphytic algal samples were collected Fall 1997, April–November 1998, and May–October 1999. Two hundred sixteen periphytic algal taxa were identified. These taxa included 137 Bacillariophyceae, 33 Cyanophyta, 40 Chlorophyta, 8 Xanthophyceae, and 3 Euglenophyta. Several species of algae found in the river appear to be previously undescribed taxa. Two of these organisms were described as new species, Nitzschia sheyennensis and Nitzschia dakotensis (Bacillariophyceae). The distribution of the periphytic algae was correlated to changes in the selected environmental variables using canonical correspondence analysis (CCA) and mult-dimensional scaling (MDS). The statistically significant environmental variables were nitrite-nitrate, pH, arsenic, potassium, magnesium, manganese, and total dissolved solids. A reservoir, Lake Ashtabula on the river was formed by a dam in 1954. In the initial statistical analysis, the effects of this reservoir on the periphytic algae downstream were so great that an upstream/downstream covariable had to be used. Further statistical analysis was used to determined that this effect could be correlated to changes in the nutrient levels rather than hydrologic changes.     

Effects of nitrogen,phosphorus and carbon enrichment on planktonic and periphytic algae in a softwater,oligotrophic lake in Florida,USA

The objective of this study was to investigate nutrient limitation of algal abundance in Anderson-Cue Lake, a softwater clear oligotrophic lake in north-central Florida. Nutrient diffusing clay pots and cylindrical enclosures were used in the field to test effects of different combinations of nitrogen, phosphorus, silica, and carbon on algal standing crop and composition of periphytic and planktonic algae, respectively. Effects of nutrient enrichment on periphytic algae were examined in two studies conducted 31 May – 8 July and 10 June – 15 July 1991. Nutrient effects on planktonic algae were examined in one study from 13 June – 1 July 1991. Planktonic and periphytic algal biovolume was significantly higher (p<0.05) when nitrogen and carbon were added in combination than with treatments without nitrogen, carbon, or nitrogen and carbon. Treatments with nitrogen and carbon combined resulted in lower algal diversity and dominance by coccoid green algae andScenedesmus. Results indicate that carbon and nitrogen can be limiting factors to algal growth in Anderson-Cue Lake and possibly other lakes of similar water quality.     

空间层次及人工基质对着生藻类建群特性的影响

为全面了解着生藻类在建群中群落变化的生态学特性,揭示着生藻类的建群规律,在以丝状藻类为优势藻的生态塘中,采用花岗岩和瓷砖为附着材料,设置水体底部和中部为附着位点,进行频次为10d的采样分析。结果表明,生态塘中共检出8门73属117种着生藻类,其中以硅藻、蓝藻、绿藻为优势类群。同时不同人工基质和不同空间层次条件下着生藻类的建群特征较一致,早期以单细胞硅藻如舟形藻(Navicula sp.)、脆杆藻(Fragilaria sp.)、曲壳藻(Achnanthes sp.)等为优势,后期以丝状藻类如鞘丝藻(Lyngbya sp.)、颤藻(Oscillatoria sp.)、伪鱼腥藻(Pseudanabaena sp.)等为优势;研究结果发现不同人工基质(花岗岩和瓷砖)对着生藻类的种类组成、细胞密度、生物量和藻类多样性无显著影响,花岗岩和瓷砖上附着的着生藻类具有较高的相似性;但不同的空间层次对着生藻类建群特征影响明显,水体底部具有更多的硅藻种类数,中部具有更多的绿藻,随着建群时间的发展,蓝藻比例不断增加;就生物量而言,底部的着生藻类叶绿素a显著高于水体中部,但两者的细胞密度无显著性差异;随着建群过程的发展,水体底部的着生藻类生物量达峰值所需的时间比中部更长。通过相关性分析,生态塘中着生藻类的生长主要受总磷的影响。     

Structure of the Phytoplankton Community and Its Relationship to Water Quality in Donghu Lake, Wuhan, China

The phytoplankton community structure, in terms of species composition, total standing crop,and abundance of the dominant algal species, at four stations in Donghu Lake, Wuhan, China, was investigated monthly from January 1994 to December 1996. A total of 260 taxa was observed, of which Chlorophyta (106 taxa) contributed the highest portion of the total number of taxa, followed by Bacillariophyta (82 taxa)and Cyanophyta (32 taxa). The total standing crop measured by means of chlorophyll a content, cell density,and cell biovolume, as well as the abundance of the dominant species, declined in the order of Station I to Station Ⅳ. Seasonal changes of the standing crop varied greatly among the four stations. Although the cell density at the four stations showed a single peak within a year, the peak density varied from July to November, dependent on the sampling year and the station. For chlorophyll a content and cell biovolume,multiple peaks were observed at Stations Ⅰ and Ⅱ, but a single peak was found at Stations Ⅲ and Ⅳ. The phytoplankton community structure indicated that the trophic status was the highest at Station Ⅰ (most eutrophic), followed by Station Ⅱ; Stations Ⅲ and Ⅳ were the least trophic areas. The long-term changes in phytoplankton community structure further suggested that changes in phytoplankton community structure were correlated with water quality, and eutrophication of Donghu Lake had been aggravated since the 1950s.     

晋阳湖丝状蓝藻的形态学分析与分子鉴定北大核心CSCD

蓝藻是地球上最古老的生物之一,其形态结构较为简单,为产氧型光合作用的原核生物。山西省晋阳湖为华北地区最大的人工湖,该研究以采自晋阳湖水体及岸边附着的蓝藻为材料,采用经典毛细管法分离纯化出5株丝状蓝藻,利用光学显微镜观察其形态结构特征(如细胞形状、藻丝体宽度、是否有鞘)和显微结构,并采用16S rRNA序列分析其系统发育关系,以明确晋阳湖的蓝藻种类,为预防湖泊蓝藻水华的发生、维护水资源环境稳定与生态平衡提供理论数据。结果显示:(1)所分离纯化的5株丝状蓝藻依形态特征归属于3个科,其中2株(JYH005和JYH012)为细鞘丝藻亚科(Leptolyngbyaceae),2株(JYH008和JYH022)为伪鱼腥藻科(Pseudanabaenaceae),1株(JYH010)为沙丝藻科(Desertifilaceae)。(2)基于16S rRNA序列构建的系统发育树显示,5株丝状蓝藻中JYH005为结丝藻属(Nodosilinea)的一种;JYH008可归为Arthronema,该株蓝藻在培养条件下观察到不同的形态特征,可能为新物种;JYH010为沙丝藻属(Desertifilum)的一种;JYH012可归为细鞘丝藻属(Leptolyngbya);JYH022与伪鱼腥藻科聚为一支,由于与该科其他藻相似度低于90%,且不能聚为一支,因此只能归为伪鱼腥藻科。研究表明,基于16S rRNA序列系统发育分析与形态学鉴定结果相一致。该研究结果丰富了山西省晋阳湖丝状蓝藻的多样性,为该湖的资源利用和环境保护提供了一定的科学依据。     

Functional diversity and trait–environment relationships of periphytic algae in subtropical floodplain lakes

Assembly rules are ecological processes imposed on a regional species bank to establish the structure of communities and define diversity patterns regarding space and time. Here, we investigated the trait distribution of periphytic algae in floodplain lakes that are naturally under contrasting environmental pressures with and without flood pulse action (low and high water phases) and the relationship between functional traits and environmental variables at regional and local scales. We hypothesized that functional clustering will be related to the low water phase in local scale, based on environment filters, and functional overdispersion to the high water phase in regional scale. With respect to traits, we can expect that the flood pulse would favored the prevalence of nanoperiphyton, filamentous forms and loosely attached. For this, we conducted a two-year assessment of the structure and dynamic of periphytic algae communities regarding their functional traits in lakes belonging to two sub-basins in a subtropical floodplain (upper Paraná River floodplain). The samplings occurred during the high water phase in 2010 and 2011 and the low water phase in 2011. The functional diversity values of the communities were quantified and compared with the mean value of communities randomly generated using null models. The relationships between functional traits and environmental variables were examined using RLQ analysis. We have shown that the traits respond to abiotic factors, and they indicated overdispersion in high water phase, and higher functional diversity in most preserved environments with absence of the pulse. The flood pulse favored the prevalence of colonial life form, stalked, entangled and heterotrichous species. This study showed spatial and temporal differences in the limnological characteristics between the lakes caused by hydrological phase and local forces in different sub-basins and the importance mainly of assimilable nutrients in the evaluation of trait–environment relationships. The overdispersion result can be assigned to flood pulse, which promotes a higher probability of dispersion and colonization of new areas for rare species, disturbance and more heterogeneous habitats, allowing opportunities for resource partitioning and regeneration of different species strategies. Moreover, the higher periphytic algae functional diversity in preserved sites emphasizes the importance of understanding ecological patterns linked to environmental degradation, as well as of conservation initiatives, because variation in periphytic algal communities implies in changes in the trophic structure, dynamics and in the functioning of environments.     

人为营养物质输入对汉丰湖不同营养级生物的影响--稳定C、N同位素分析

以长江一级支流小江上游的汉丰湖为研究对象,设置了4个采样点(影响组:A, B;对照组:C, D),应用碳、氮稳定性同位素探讨人类生活污水和农业面源污染对汉丰湖水生生态系统中不同营养级水平生物类群的影响。结果表明:影响组POM(颗粒有机物)和螺类碳、氮稳定性同位素比值范围分别为-25.93‰--24.63‰、4.12‰-9.86‰,-14.28‰--21.60‰、7.97‰-19.99‰;对照组POM(颗粒有机物)和螺类碳、氮稳定性同位素比值范围分别为-25.62‰--22.51‰、0.01‰-6.56‰,-22.96‰--19.21‰、6.75‰-8.89‰;不同组间POM和初级消费者螺类碳同位素比值无明显空间变化(P>0.05), 而氮稳定性同位素比值空间变化显著(P<0.05)。因此,在汉丰湖食物网中,氮稳定性同位素特征更好地反应了营养物质(人为输入)吸收和富集的信息。与固着藻类、鱼类等相比,POM和软体动物螺类更适合作为环境评价的指示物。影响组A、B样点的部分生物类群已经受到了人为营养物质输入的影响,影响强度B样点区域>A样点区域。结果建议加强汉丰湖水环境保护,控制污水排放量及提高污水处理水平,对于保护小江和三峡库区水质具有十分重要的意义。     

Structure of the Phytoplankton Community and Its Relationship to Water Quality in Donghu Lake, Wuhan, China

The phytoplankton community structure, in terms of species composition, total standing crop,and abundance of the dominant algal species, at four stations in Donghu Lake, Wuhan, China, was investigated monthly from January 1994 to December 1996. A total of 260 taxa was observed, of which Chlorophyta (106 taxa) contributed the highest portion of the total number of taxa, followed by Bacillariophyta (82 taxa) and Cyanophyta (32 taxa). The total standing crop measured by means of chlorophyll a content, cell density,and cell biovolume, as well as the abundance of the dominant species, declined in the order of Station I to Station IV. Seasonal changes of the standing crop varied greatly among the four stations. Although the cell density at the four stations showed a single peak within a year, the peak density varied from July to November, dependent on the sampling year and the station. For chlorophyll a content and cell biovolume,multiple peaks were observed at Stations I and II, but a single peak was found at Stations III and IV. The phytoplankton community structure indicated that the trophic status was the highest at Station I (most eutrophic), followed by Station II; Stations III and IV were the least trophic areas. The long-term changes in phytoplankton community structure further suggested that changes in phytoplankton community structure were correlated with water quality, and eutrophication of Donghu Lake had been aggravated since the 1950s.     

In situ interactions between the effects of season,current velocity and pollution on a river biofilm

1. The development of periphytic algae and bacteria is controlled by a combination of interacting biotic processes and abiotic factors. Distinguishing between the selection pressure resulting from pollution and that of natural environmental factors is therefore one of the most critical aspects of assessing the impact of pollutants on the diversity and function of benthic microbial communities in natural ecosystems. 2. We studied how current velocity and season affect the ability of river biofilms to cope with complex chemical pollution. We compared the diversity, structure and production of periphytic algae and bacteria from four sampling zones with differing chemical water quality levels and different flow velocities over the course of two seasons (summer and winter). 3. The three factors tested all influenced biofilm development, but this depended on the biological variable being measured. Bacterial and algal densities were highly dependent on season and chemical water quality. Algal density was lower in summer than in winter, but bacterial density and production increased from upstream (reference) to downstream (polluted), and this increase was more marked in winter. The impact of chemical water quality was also dependent on the season. 4. An interaction between current velocity and pollution was also detected. During the summer, there was no difference in bacterial density or production between the upstream and downstream segments in the fast current zones, whereas both variables were higher downstream in the slow current zones. Such interactions between environmental factors and the impact of water quality on biofilms must be taken into account in assessments of the effects of chemicals on biofilm community structure and functioning in rivers.     

Comparative abundance-frequency assessment exampled by data from the Bergumermeer,a lake in the Netherlands

Summary In the years 1969–1978 chemical and plankton samples were collected monthly in the Bergumermeer, province of Friesland. The samples were analysed by biologists of the KEMA, a company for testing of electrical equipment, who were interested in the environmental impact of heat discharge from the electricity power plant at the lake side. The observations were compiled in three reports and they offered an opportunity to try out a particular method for the presentation of the results. This method is described as comparative abundance-frequency assessment for the characterization of surface water as derived from plankton investigation (LEENTVAAR and VAN DE MECHE-JACOBI, 1984).In the case of the Bergumermeer the method showed also good results. The influence of Lake De Leyen, which in the south is connected to the Bergumermeer by a small canal, was demonstrated by finding other maxima and minima of chlorid, phosphate, nitrate and plankton algae. At the other sampling stations the values did not differ essentially, which means that in the Bergumermeer the water is mixed and the algal distribution is homogeneous. This may be related to the rather short retention time of the water. The temperature data are interesting in relation to the heat discharge from the power plant. After the use of cooling water which started in 1974 the sampling station at the outlet showed every month higher temperatures than the other stations. Plankton and chemistry was not affected at this station.     

着生藻类和浮游藻类在三峡库区河流健康评价中的适宜性比较研究

藻类对水体环境变化敏感,其种类和数量与环境因素有密切联系并因环境的变化而发生变化,因此藻类常作为河流健康评价的指示生物。水体中的藻类根据生活习性不同分为着生藻类和浮游藻类,在河流健康评价中,以往的工作中有的采用浮游藻类用于河流健康评价,有的采用着生藻类用于评价,但浮游藻类和着生藻类究竟何者用于河流健康评价更适宜,抑或是二者在用于评价的适宜性上没有明显差别,迄今为止未开展过深入研究。选择三峡库区内的两条河流嘉陵江和乌江作为研究对象,于2015年9月,在两条河流上共布设11个研究断面,对嘉陵江、乌江的水环境理化因子、着生藻类和浮游藻类群落进行调查研究,应用着生藻类生物完整性指数(Periphytic algal index of biological integrity,Pe-IBI)和浮游藻类生物完整性指数(Phytoplankton index of biological integrity,Ph-IBI),并结合水体综合污染指数(Comprehensive pollution index,CPI),对嘉陵江、乌江的健康状况进行评价。研究结果表明,采用着生藻类生物完整性评价(Pe-IBI)能筛选出7个核心生物参数(藻类总分类单元数、蓝藻总分类单元数、绿藻总分类单元数、菱形藻比例、优势分类单元比例、香农多样性指数、均匀度)用于河流健康评价,着生藻类生物完整性指数(Pe-IBI)与水体综合污染指数(CPI)具有极显著的负相关关系,并且与水体中总氮、铅含量也有极显著的负相关关系,表明水环境质量越低则着生藻类的生物完整性越差;当采用浮游藻类生物完整性(Ph-IBI)用于河流健康评价时却只能筛选出1个核心生物参数(藻类密度),而且浮游藻类生物完整性指数(Ph-IBI)与水体综合污染指数(CPI)及12个水体环境指标并无明显的相关性。本研究表明,在河流水体中,与浮游藻类相比,着生藻类更能反映水体环境的状况,对河流水体环境的反映更为准确。因此,在以流动水体为特征的河流的健康评价中,采用着生藻类比采用浮游藻类更为适宜。     

Primary production of phytoplankton and periphyton in two humic lakes of a South American wetland

Seasonal primary productivities of periphyton and phytoplankton were compared in Grande Lake (GL) and a relict oxbow lake (ROL) in winter 2006 and summer 2007. GL was free of floating plants on the sampling dates and covered over 80 and 100% of the ROL surface in winter and summer, respectively. The ¹⁴C assimilation technique was used to obtain the P–E curves of phytoplankton and periphyton on artificial substrata. The periphytic maximum photosynthetic rate (P _max) was higher in the ROL in winter and summer, being better adapted to low irradiances than those in the GL. Phytoplankton and periphytic algae were light-limited in the ROL in summer due to complete coverage by floating macrophytes. In summer, P _max and α values for periphyton in the ROL were higher than those for phytoplankton, and were even higher than in GL. In turn, P _max and α values for phytoplankton in Grande Lake were higher than those for periphyton due to improved light conditions and the presence of algae that were adapted to movement through the water column. These results suggest that the complete coverage by floating macrophytes restricted phytoplankton productivity and allowed the development of a periphytic community that was better adapted to low-light conditions.