Site Variation in Littoral Periphyton Populations: Correlation and Regression with Environmental Factors

Over a six month period, littoral periphyton communities on vertically oriented glass slides were quantitatively sampled from four stations in Elk Lake, British Columbia. Correlation and multiple regression analyses were employed to assess the temporal interrelationships between 15 environmental variables, concurrently measured, and the periphyton populations, expressed as total cell counts and species diversity, for the complete data set of each station. At all stations there was a statistically significant increase in total cell populations with increasing length of slide exposure; positive correlations also occurred with pH, temperature, nitrite, nitrate and copper, while negative ones occurred with oxygen, orthophosphate and hardness (magnesium and total). At all but one station there was a significant decrease in species diversity with increasing slide exposure duration, a decrease attributed to the simultaneous increase in standing crop resulting in intensified competition for diminishing substrate area suitable for cell colonization. Multiple stepwise regression analyses demonstrated that greater than 80% of the variation in periphyton total cells at all four stations could be reliably predicted or described in terms of length of slide exposure, phosphate (ortho and total), and hardness (calcium and total). On the other hand, exposure duration and total cell populations were the most important variables associated with changes in species diversity at three of the four stations. In general, correlations and regressions between standing crop and environmental variables were more statistically reliable and consistent between stations than comparable analyses with species diversity. Use of multiple regression and correlation disclosed the importance of small, non statistically significant variation in ecologically relevant variables and permitted objective comparison of stations.     

Periphyton nutrient limitation and other potential growth-controlling factors in Lake Okeechobee,U.S.A.

Periphyton nutrient limitation was assessed in Lake Okeechobee, a large, shallow, eutrophic lake in the southeastern U.S.A. Nutrient assays were performed to determine if the same nutrients that limit phytoplankton also limit periphyton growth in the lake. Nutrient diffusing clay substrates containing agar spiked with nitrogen, phosphorus, or both, along with nutrient-free controls, were incubated at four sites in the lake. Three sites were located in a pelagic–littoral interface (ecotone) and one site was located in the interior littoral region. Incubations lasted for 20–26 days, and were repeated on a quarterly basis between 1996 and 1997, to incorporate seasonal variability into the experimental design. The physical and chemical conditions at each site also were measured. Periphyton biomass (chlorophyll a and ash-free dry mass) was highest at the littoral and northern ecotone sites. At the littoral site, nitrogen limited biomass in four of five incubations, although the largest biomass differences between the treatments and controls (3 g cm^–2 as chl) were probably not ecologically significant. Periphyton biomass at the western and southern ecotone sites was low compared to the other two sites. Increases in water column depth and associated declines in light penetration strongly correlated with periphyton growth and suggested that they may have limited growth most often at all three ecotone sites. Nitrogen also was found to limit periphyton growth approximately 20% of the time at the ecotone sites and phosphorus was found to limit growth once at the west site.     

Assessment of Water Pollution using Diatom Community Structure and Species Distribution — A Case Study in a Tropical River Basin

A study on biological assessment of water pollution using diatom community structure and species distribution was carried out in the Linggi River Basin, Malaysia which was polluted by various urban, industrial and agricultural wastes. A total of 86 diatom taxa belonging to 21 genera were recorded from all eight sampling stations located in the basin, of which 70 species were found on artificial substrates; the remaining 16 species were recorded exclusively on natural substrates. The number of diatom species observed between the stations varied from 22-47 species. The dominant diatom species in decreasing order of abundance were Eunotia vanheurckii, Nitzschia palea, Achnanthes saxonica, Gomphonema parvulum and Achnanthes minutissima. The most common clean water species were Achnanthes minutissima, A. linearis and Synedra rumpens. The most tolerant species were Nitzschia palea followed by Gomphonema parvulum and Pinnularia braunii. Eunotia vanheurckii and Navicula cryptocephala occurred in high densities at both unpolluted and polluted stations and can be considered as the common facultative or indifferent species. Although a large number of species were recorded at the unpolluted stations, equivalent number of species were also found at the moderately polluted stations. However, the number of species was reduced at grossly polluted stations. Nevertheless, a marked variation in species association exists between the unpolluted and polluted stations, but not among the polluted stations to distinguish the type and degree of pollution.     

Diatom colonization dynamics in a lotic system

A series of three overlapping sets of slides were exposed in riffle and pool habitats in a fourth order river in the Upper Peninsula of Michigan. Each set was exposed for 6–8 weeks and overlapped the preceeding set by 2 weeks. Diatom cell densities and community structure were determined after daily or weekly exposure periods for each set. The first set was placed on August 4, 1982, and the third set removed on October 16, 1982. Species diversity and evenness peaked quickly during colonization. Both indices decreased as the length of exposure increased. Early colonizing diatom species that occasionally accounted for large proportions of the total diatom community were soon replaced by other diatom species that tended to persist through time. Major dominant species were well established by day 28. Severe net cell losses (up to 17% of the total density) were recorded after only an 8–9 day exposure in both pools and riffles. Pool slides showed greater cell densities during the first few day's exposure than did slides exposed in riffle zones. After this brief conditioning period, however, the riffle slides showed more rapid cell growth and/or accumulation rates. Mean cell densities were similar between pool and riffle slides after 6–8 week exposures.Seasonal changes appeared to strongly influence diatom species succession. Seasonal changes in water velocity, temperature, or light may have the same effect as the more dramatic flood events which reset periphyton to earlier successional stages, resulting in increased major changes in species composition of the periphyton diatom community.     

Diatom Diversity in Chronically versus Episodically Acidified Adirondack Streams

The relationship between algal species richness and diversity, and pH is controversial. Furthermore, it is still unknown how episodic stream acidification following atmospheric deposition affects species richness and diversity. Here we analyzed water chemistry and diatom epiphyton dynamics and showed their contrasting behavior in chronically vs. episodically acidic streams in the Adirondack region. Species richness and diversity were significantly higher in the chronically acidic brown water stream, where organic acidity was significantly higher and the ratio of inorganic to organic monomeric aluminum significantly lower. Conversely, in the episodically acidic clear water stream, the inorganic acidity and pH were significantly higher and the diatom communities were very species‐poor. This suggests that episodic acidification in the Adirondacks may be more stressful for stream biota than chronic acidity. Strong negative linear relationships between species diversity, Eunotia exigua, and dissolved organic carbon against pH were revealed after the influence of non‐linear temporal trends was partialled out using a novel way of temporal modeling. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Plankton Succession in the Temporary Lake Koronia after Intermittent Dry‐Out

This study examines the plankton succession in a polluted temporary lake after intermittent dry‐out. The initial stage after flooding was heterotrophic (zooplankton/phytoplankton carbon biomass ratio > 1). Phytoplankton species richness increased exponentially within a few months after inundation. The chlorophyte Koliella cf. longiseta was the pioneer colonist which was replaced by Oocystis sp. reaching 300 340 ind mL^–1. The initial conditions favored rotifer and cladoceran colonists, not previously recorded, to successfully establish populations. The species that finally became dominant hatched from the lake's sedimentary egg bank with Daphnia magna being prominent. Nevertheless, the zooplankton community was unable to control the high biomass of chlorophytes (zooplankton/phytoplankton carbon biomass ratio < 0.4). Plankton succession in this temporary lake was mostly determined by the past phytoplankton – zooplankton species pool rather than by the established new colonists. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

周丛藻类及其在水质净化中的应用

周丛藻类广泛存在于自然界水体中,具有生物量大、生态功能强、水质响应灵敏等特征.周丛藻类通过吸收代谢利用、吸附和络合等过程去除水体污染物质,用于水质净化,具有耐污能力强,N、P去除效果好,藻类细胞回收利用价值高等优点,推广应用前景广阔.近年开发的藻丛刷系统、周丛藻类 生物膜系统和周丛藻类水产养殖系统等已经成功用于畜禽水产养殖废水、生活污水处理.而周丛藻类的生存规律、对污染物浓度的生理响应机理和污染物质吸收利用的分子生物学机制仍有待进一步研究.     

Littoral zone of Lake Ladoga: ecological state evaluation

The littoral zone of a lake is an important ecotone between terrestrial and aquatic systems. From the point of view of the lake ecosystem, much of the mineral, organic and toxic substances entering the lake from the drainage basin are transformed in the littoral zone by physical processes and biochemical pathways. The littoral zone of Lake Ladoga can be divided into three main regions: the shallow southern region, the fairly steep western and eastern shorelines, and the northern archipelago. In these regions, the communities of aquatic macrophytes, periphyton, phyto- and zooplankton and meio- and macrobenthos have been extensively studied. This paper presents numerical data on these communities, with special reference to comparisons between areas subjected to different degrees of anthropogenic loading. Most of the communities are characterized by high species diversity and spatial heterogeneity, especially among the macrophyte associations in which intensive production and decomposition takes place. Water dynamics and water exchange rate are the main abiotic factors in the formation of littoral communities. The characteristics of plant associations and bottom substrate, rather than pollution, appear as the most important factors structuring meio- and macrobenthic invertebrate communities in the littoral.     

五鹿山国家级自然保护区森林群落演替分析

植物群落演替分析对植被恢复,森林管理等有重要的意义。以空间代替时间的方法,搜集数据,运用TWINSPAN和DCA进行分析。结果表明:五鹿山植物群落的演替系列:酸枣灌丛→荆条灌丛→黄刺玫灌丛→白皮松+侧柏林→白皮松林→油松林→辽东栎林;虎榛子灌丛→茶条槭灌丛→华北落叶松林→白桦林。这可以作为五鹿山植物群落演替的模型。在演替进程中物种的结构、组成以及生活型变化显著。使用六个指数来分析演替过程中物种的异质性、均匀度和丰富度变化。随着演替的进行,物种异质性、丰富度均有所增加,均匀度逐渐降低。     

Biological Assessment of Water Pollution Using Periphyton Productivity and Standing Crop in the Linggi River,Malaysia

Many assessments of water pollution in aquatic ecosystem have focused mainly on physical and chemical characteristics. However, until recently, biological aspects have been given little attention. Although physical and chemical methods of assessing water pollution are relatively simple to interpret, biological assessments have many strong merits. Therefore an attempt was made to use periphyton productivity (in terms of biomass ash‐free dry weight, AFDW) and chlorophyll‐a content (measured from periphyton colonized on glass microscope slides) to assess water pollution in the Linggi river. The Linggi River is a tropical lotic system in the country of Malaysia. As a result of increased nutrient enrichment due to sewage and agro‐industrial wastes, analyses of accumulated periphyton on glass slides showed increased biomass AFDW from an unpolluted upstream reach to the highly polluted downstream reach of the river. In contrast to biomass, the chlorophyll‐a content of the accumulated periphyton was not always directly related to the AFDW of the biomass. Though the highly polluted Station 4 showed high biomass AFDW and chlorophyll‐a, due to increased nutrient enrichment. The chlorophyll‐a values at slightly polluted Station 2 were lower than at the unpolluted Station 1. Meanwhile, the mean chlorophyll‐a content observed in Linggi river was relatively high as compared to previous studies carried out in Malaysia. When the Water Quality Index (WQI) was calculated using key chemical parameters linked to organic pollution, there was a significant correlation between chemical parameters, biomass AFDW, and chorophyll‐a. Though the chlorophyll‐a content increased with decreases in the WQI, similar to the biomass AFDW, the chlorophyll‐a values were found to be lower in slightly polluted Station 2 than unpolluted Station 1. Therefore it was not necessary that an increase in the biomass AFDW, due to nutrient enrichment, would always increase the chlorophyll‐a in accumulated periphyton (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Effect of urban and industrial wastes on species diversity of the diatom community in a tropical river,Malaysia

Monthly species diversity and other components of diversity of diatom samples collected over a period of one year at eight stations in the Linggi River Basin, Malaysia were analysed. Species diversity ranged between 0.52–3.62 bits individua^–1. Among the four stations located in the Linggi River (sensu stricto), highest diversity values were recorded at a station polluted by rubber effluent, followed by the stations unpolluted from point sources. Lowest diversity was recorded at a station polluted with urban sewage. At Kundor River, highest diversity was recorded at stations located downstream of rubber and palm oil waste discharges. On the whole, diversity values at unpolluted stations were always lower than at mildly polluted stations. Severe organic loadings caused low diversity by reducing the number of species (species richness) but did not increase the evenness (equitability) as expected when compared with unpolluted or mildly polluted stations. The changes in species diversity can be related to changes in diatom community structure and thereby changes in water quality, but cannot be used as an index of water quality.     

Periphyton growth and diatom community structure in a cooling water pond

Periphyton (Aufwuchs) accumulation was measured on artificial substrates in a pond in central Finland which receives warm cooling-water effluent from a power plant. The growth of periphyton was generally more rapid on the substrates during the first two weeks of colonization near the inflow of the warm water effluent than in the middle of the pond. The maximum accumulation of periphyton was in spring and autumn (dry weight maximum at warm effluent was in spring 3.5 mg DW cm⁻²,2.65 mg AFDW cm⁻²; chlorophyll a maximum 3.96 μg cm⁻² was found in autumn at pond-middle station). During mid-winter months the growth was strongly limited by solar radiation, but the growth was also slow at both stations in the summer months, when the power plant was out of operation. The periphyton accumulation rate was fastest near the water surface and decreased rapidly with increasing depth. A total of 167 diatom species were found in periphyton samples. However, most species were rare; many of the dominants were common to both plankton and periphyton. Species similarity analyses (Jaccard's similarity) between 10 different diatom communities (including periphyton from 9 different types of substrates and phytoplankton) indicated low similarity index values although differences between communities were not significant.     

Periphyton on nymphaeids: An evaluation of methods and separation techniques

The use of certain methods and techniques of periphyton research has been evaluated in connection with the study of periphyton on nymphaeid aquatic plants. Separation techniques explored are based on a combination of mechanical and chemical forces, on enzymatic action and on the chelating activity of EDTA. Mechanical separation by the application of superficial film is treated apart, because it is the only technique conserving the original pattern of periphyton. The means used to examine periphyton in situ consist of bleaching, epifluorescence and scanning electron microscopy.In the end, it is concluded that not one of the techniques is fully satisfactory. However, a combination of techniques may provide sufficient data to obtain an overall picture of species composition, microdistribution and architecture of a periphyton community.Contribution no. 30 of the nymphaeid project.Contribution no. 30 of the nymphaeid project.     

The Relationships Among Disturbance, Substratum Size and Periphyton Community Structure

Numerous studies have determined the effects of physical disturbance on periphyton, however, the substrata used have varied in size among studies. In this study we examined the influence of substratum size on the change in periphyton exposed to three levels of disturbance. Periphyton communities were established in a large greenhouse tank on square unglazed tiles that were either 2.5, 5, or 7.5 cm on a side. Following community development sets of tiles were randomly assigned to controlled disturbances removing 25%, 50%, or 75% of the community or an undisturbed control. Following disturbance, changes in periphyton density were associated with both disturbance treatment and tile size as was taxa richness. Experimental results and direct observation revealed that algal growth was most concentrated along the edge of the tile and progressively declined toward the center. Thus, substratum size influences colonization and pre-disturbance community structure, which then affects the extent of periphyton community change due to different levels of disturbance.     

Seasonal Dynamics of Periphyton in a Large Tropical Lake

Tropical aquatic systems are generally assumed to have little seasonality in productivity patterns. However, this study indicated that there was substantial seasonal variation in epilithic productivity and biomass in tropical Lake Tanganyika, due primarily to seasonal patterns in lake hydrodynamics that influence nutrient availability. Although they support much of the lake’s biological diversity, epilithic algae made a minor contribution to the total energy budget in Lake Tanganyika. A comparison among large, oligotrophic lakes revealed no significant latitudinal trends in periphyton productivity or biomass. However, Lake Tanganyika has relatively low benthic algal biomass and is therefore more efficient at photosynthesis than the temperate lakes. The influence of wave action and consumer density and diversity may be important in moderating productivity of the epilithic community.     

Periphyton removal related to phosphorus and grazer biomass level

1. The proliferation of nuisance periphyton in enriched streams may be dependent on the biomass of the grazing macroinvertebrates present. In the present study, the effectiveness of grazer size and biomass in controlling periphyton and the extent to which grazing effectiveness was affected by enrichment level were determined. 2. Two sets of experiments with two caddisfly grazers were conducted in laboratory channels during spring and summer 1995 and 1996. The first set tested the combined effect of phosphorus enrichment and grazing, while the second set tested the effect of variable grazer biomass on periphyton biomass. 3. Grazing reduced periphyton biomass in excess of 80%, compared to ungrazed controls. Grazers were equally effective in controlling filamentous green algae, Stigeoclonium, diatoms and small colonial greens. Near complete removal of periphyton biomass by grazing occurred at even at the lowest grazer biomass level (750 mg m^??2, i.e. approximately one-third of natural levels). 4. Grazing controlled periphyton biomass more than did enrichment with soluble reactive phosphorus (SRP). 5. Grazing rates in the phosphorus-grazing interaction experiments averaged about 6 mg chl a g invertebrate^??1 day^??1, which was similar to past work in these channels and elsewhere, while rates were about five-fold higher in the variable grazer biomass experiments. 6. Simulating effects of SRP and grazing with a calibrated model suggests that higher SRP levels would be necessary to exceed a nuisance periphyton biomass level if grazers were present. However, if grazer biomass was more than 1500 mg m^??2, a nuisance level would probably not be exceeded at any SRP.     

子午岭植被自然演替中植物多样性变化及其与土壤理化性质的关系

在野外样方调查和室内实验分析的基础上,采用相关性分析和多元逐步回归方法,分析了黄土高原子午岭地区不同演替阶段群落物种多样性、土壤理化特性以及二者的相互关系.结果表明:群落物种多样性随演替进展呈增长趋势,但其增长并非完全线性,主要表现为草本群落演替阶段物种多样性指数高于灌木演替阶段.0~20 cm和20~40 cm土层土壤的全氮、有效氮和有机质等土壤养分指标随着植被演替不断增大.在演替过程中,土壤含水量变化虽有波动,但总体上升,土壤容重波动下降,说明演替过程中土壤环境在不断得到改善.40~60 cm土层土壤理化性质变化未表现出一定规律,说明其与植被演替没有必然联系.物种多样性指数与土壤因子的相关性分析表明,群落演替过程中物种多样性变化与土壤因子存在一定相关性,其中0~20 cm土层土壤的全氮和有机质与物种的多样性指数呈显著正相关.随着土层加深,物种多样性对土壤理化性质影响表现出减弱趋势.     

演替理论与植被恢复

《昆明-蒙特利尔全球生物多样性框架》提出要高质量保护和恢复各30%的土地,最大化地实现保护生物多样性和缓解气候变化的目标,而演替理论和植被恢复可以为实现30%的保护和恢复目标服务。演替理论是植被生态学中的核心理论,演替是指在一个地点上由一群不同物种组成的生命体的结构或组成随时间而变化的过程;植被恢复是以植物种植、配置为主,恢复或重建植物群落或天然更新恢复植物群落的过程,植被恢复是生态系统结构和功能从简单到复杂、从低级向高级变化的过程,最终目的是建立健康稳定的植物群落。演替是植被恢复的基础,植被恢复被视为对演替过程的操纵,以达到恢复受损植被生态系统的目标。演替理论可以指导植被恢复,而植被恢复对演替理论的发展有益。演替按裸地性质可以分为原生演替和次生演替,有研究建议将恢复过程视为第三演替,这将有助于理解通过人为干预促进植被恢复成功的管理选择,特别是通过强调退化生态系统中的环境和生物遗存的管理选择。此外,该文还提出了植被恢复理论和演替理论未来可能重点关注的科学和技术问题。     

Periphyton community responses to elevated metal concentrations in a Rocky Mountain stream

The effects of elevated metals on stream periphyton in the Eagle River, a mining impacted river in central Colorado, were assessed in 1991 and 1992 using assemblage information (taxa richness, community similarity) and non-taxonomic measures (biomass, chlorophyll a, autotrophic index). The number of periphyton genera collected ranged from 2 at a site adjacent to abandoned mining operations to 21 at a downstream site, but was not significantly correlated with dissolved metals concentrations. Fragilaria and Achnanthes were the dominant genera at all sites, with Fragilaria dominating the less impacted sites and Achnanthesdominating at the more impacted sites. Taxonomic similarity was greatest among those sites receiving the greatest inputs of metals from mining operations, where the coefficient of similarity ranged from 0.87 to 0.99. Cluster analyses revealed significant differences among sites adjacent to the mine and either the upstream or downstream sites. Chlorophyll a content of periphyton and the autotrophic index in both years showed significant downstream decreases associated with increasing dissolved metals concentrations. Overall, the periphyton community data were able to separate metal contaminated sites from reference or less impacted sites, and responded in predictable ways to increasing metal concentrations of Eagle River water.