Small Urban Lake Research Articles

Chemical composition of sediment and macrozoobenthos of small urban lakes, the Republic of Karelia, Russia

Assessing the benthic communities in water bodies under increasing anthropogenic pressure seems to be an urgent task of scientific research aimed at short-term and long-term monitoring of water bodies. This study focuses on the chemical composition of modern sediment and the current state of macrozoobenthos of small lakes in the Republic of Karelia (Kitaiskoe and Plotichie) influenced by anthropogenic factors. It was discovered that the lakes of Medvezhyegorsk have a higher concentration of heavy metals (such as lead (Pb), cadmium (Cd), molybdenum (Mo), and antimony (Sb),) compared to the Earth’s crust and natural background levels. The current study established the significant impact of industry and transportation on the movement and build up of pollutants in these lakes. The qualitative and quantitative parameters analysed for the benthic communities in the littoral and profundal zones included the species diversity, the structure of dominant species, and their percentage in the samples. According to the level of macrozoobenthos development, both reservoirs (lakes) were classified as mesotrophic, and according to the values of the chironomid index “K” as moderately polluted. The Pantle–Buck method (saprobic index) showed that the lakes can be classified as polluted (water quality class 4). Macrozoobenthos groups most tolerant to environmental conditions, for example, Chironomidae larvae, prevailed in the studied urban lakes. The economic development of the lakes leads to ecosystem transformation and long-term eutrophication over time affecting the biotic indicators of surface water quality. The results obtained can serve as a basis for complex environmental monitoring of the urbanized territories in the taiga zone.

A biological perspective for the fishery management of a small urban lake in Indonesia: a case study on the reproductive stage of the red devil (Amphilopus citrinellus) in Situ Cilodong, West Java, Indonesia

The presence and establishment of invasive alien fish species is one of the biggest threats to aquatic biodiversity. The red devil, Amphilopus citrinellus, is one of the emerging invasive species and its occurrence is massively detected in common water bodies in tropical areas such as Indonesia. However, the topic remains under-reported from the small urban lakes. This study aims to present the reproductive characteristics of the fish in Situ Cilodong, a small urban lake in the country, that can be used as a principal reference for population control. The sampling was conducted in June 2021 and May 2022 using a mix of seven mesh-sized gillnets. The results of the length-weight relationship reveal that both the female and male fish perform isometric growth type. The calculated Gonad Somatic Index (GSI) and the histological analysis confirmed that the fish is a multi-spawner species. The results imply that sustainable population control efforts must include intensive catch and engage a participatory approach between the legal authority and the local fishers.

Growth of the water fleas Daphnia magna (Straus, 1820) at different trophic levels of two small urban lakes in Indonesia

Nutrient enrichment in waters that has become a major environmental problem is related to excessive loading of nutrients into aquatic ecosystems. This nutrient enrichment, called eutrophication, favors phytoplankton growth, which can function as a natural daphnid feed. This study examined the growth performance of the water fleas Daphnia magna in water collected from small lakes (ponds) of different trophic levels. The water was taken from Situ Rawa Kalong, considered eutrophic from its dark green color, and the less eutrophic Situ Cibuntu with relatively clear water. Daphnids were grown in six aquaria filled with water from both ponds without artificial feeding with an initial density of five individuals/L. Samples of daphnids were taken every three to four days to observe their growth and reproduction, along with water samples to analyze the chlorophyll content and total suspended solids (TSS). The result showed that the eutrophic water of Situ Rawa Kalong favored phytoplankton growth, indicated by a consistently higher chlorophyll content in the water ranging from 35.3 to 140.7 μg/L compared to less eutrophic water of Situ Cibuntu with chlorophyll content ranging from 1.4 to 13.2 μg/L throughout the experiment. A much higher daphnid density of 151.7 individuals/L was achieved with more water chlorophyll content, meaning phytoplankton availability became a controlling factor for daphnid growth in the pond waters. This study reveals the functional relationships in the food chain between the water trophic level, the abundance of phytoplankton as the primary producer, and daphnids as the first-order predator. It also suggests that the open water trophic level can be managed to favor the daphnid growth, which can then be harvested for use as natural feed.

Intense methane diffusive emissions in eutrophic urban lakes, Central China

Urban lakes are hotspots of methane (CH4) emissions. Yet, actual field measurements of CH4 in these lakes are rather limited and our understanding of CH4 response to urban lake eutrophication is still incomplete. In this study, we measured dissolved CH4 concentrations and quantified CH4 diffusion from four urban lakes in subtropical China during wet and dry seasons. We found that these lakes were constantly CH4-saturated, contributing the greenhouse gas (GHG) to the atmosphere. Nutrient enrichment significantly increased CH4 concentrations and diffusive fluxes. Average CH4 flux rate in the highly-eutrophic lake zones (4.18 ± 7.68 mmol m−2 d−1) was significantly higher than those in the mesotrophic (0.19 ± 0.18 mmol m−2 d−1) and lightly/moderately-eutrophic zones (0.72 ± 2.22 mmol m−2 d−1). Seasonally, CH4 concentrations and fluxes were significantly higher in the wet season than in the dry season in the mesotrophic and the lightly/moderately-eutrophic lake zones, but an inverse pattern existed in the highly-eutrophic lake zones. CH4 concentrations and fluxes increased with elevated levels of nitrogen, phosphorus and dissolved organic carbon (DOC). The accumulation of nutrients provided autochthonous substrate for methanogenesis, indicated by a negative correlation between CH4 and the C:N ratio. Ammonium-nitrogen (NH4+-N) was the best predictor for spatial fluctuation of CH4 concentrations and diffusive fluxes in the mesotrophic and the lightly/moderately-eutrophic lake zones, while total nitrogen (TN) and total phosphorus (TP) levels showed the highest predictability in the highly-eutrophic lake zones. Based on the findings, we conclude that nutrient enrichment in urban lakes can largely increase CH4 diffusion, and that urban sewage inflow is a key concern for eutrophication boosting CH4 production and diffusive emission. Furthermore, our study reveals that small urban lakes may be an important missing source of GHG emissions in the global C accounting, and that the ratio of littoral-to-pelagic zones can be important for predicting lake-scale estimation of CH4 emission.

Performance and ecological impacts of benthic barriers for the control of an invasive plant in a small urban lake

Yellow Floating Heart (YFH), Nymphoides peltata, is a rooted aquatic plant that is not native to North America, and can quickly establish nuisance populations in shallow lakes, rivers, and wetlands. There are few documented methods for effectively eradiating or controlling YFH. Little Albro Lake is a small (3 ha), shallow (<5 m deep) meso-eutrophic lake in Dartmouth, Nova Scotia, Canada that experiences an annual YFH infestation covering >50% of the lake during the growing season. A pilot study was conducted during the 2021 growing season to: (i) assess the feasibility of using benthic barriers to control YFH growth, and (ii) investigate the potential impacts of benthic barriers on ecosystem components. Two commercially available benthic barriers (Aquascreen, a permeable barrier, and Lake Bottom Blanket, an impermeable barrier) were tested in shallow (1 m water depth) and deep (3 m water depth) areas of the lake. A total of 18 test plots (6 permeable, 6 impermeable, 6 control), each measuring 3 m × 3 m, were established in early May 2021, and monitored throughout the growing season (May–September). Both types of barriers were effective in reducing YFH growth, with barriered plots possessing significantly less YFH coverage than control plots. Inspection of the permeable barriers after their removal from the lake, however, revealed that YFH had been able to grow through this type of barrier material. Several maintenance issues were also noted with both barriers including: (i) gas build-up under the barriers, which caused billowing, and (ii) an accumulation of sediment on top of the barriers and growth of YFH through these sediment layers. Both issues would need to be managed during a full-scale benthic barrier application program. An environmental effects monitoring program was also undertaken to understand the lake ecosystem and impacts of the barriers on the chemical and biological properties of the lakebed. The barriers had measurable impacts on the lakebed and generated lower oxidation reduction potential (ORP) in sediments, as compared to control plots with no barriers. Reduced ORP in lake sediments could facilitate the mobilization of redox-sensitive metals, such as arsenic and iron. There were only minor differences in benthic macroinvertebrate populations when comparing barriered and control plots. The bacterial alpha-diversity of the lakebed sediment was shown to differ by depth, with the shallow zone having higher observed ASVs and diversity levels. However, within the two depth zones, the barriers did not appear to have a large impact on bacterial community composition and potential functionality. In conclusion, benthic barriers can be used to prevent YFH growth, however barrier installations require maintenance and may reduce sediment ORP, potentially leading to release of redox-sensitive metals and nutrients.

Calibration of a complex hydro-ecological model through Approximate Bayesian Computation and Random Forest combined with sensitivity analysis

An automated calibration method is proposed and applied to the complex hydro-ecological model Delft3D-BLOOM which is calibrated from monitoring data of the lake Champs-sur-Marne, a small shallow urban lake in the Paris region (France). This method (ABC-RF-SA) combines Approximate Bayesian Computation (ABC) with the machine learning algorithm Random Forest (RF) and a Sensitivity Analysis (SA) of the model parameters. Three target variables are used (total chlorophyll, cyanobacteria and dissolved oxygen concentration) to calibrate 133 parameters. ABC-RF-SA is first applied on a set of simulated observations to validate the methodology. It is then applied on a real set of high-frequency observations recorded during about two weeks on the lake Champs-sur-Marne. The methodology is also compared to standard ABC and ABC-RF formulations. Only ABC-RF-SA allowed the model to reproduce the observed biogeochemical dynamics. The coupling of ABC with RF and SA thus appears crucial for its application to complex hydro-ecological models.

Investigating the climatology of North China's urban inland lake based on six years of observations

There are unclear characteristics of the effect of lake breeze in small urban inland lakes due to little research on lake breezes. In this work, six-year observations were performed to study the comprehensive climatologic characteristics of lake breezes on North China's urban inland lake, Lake Hengshui (75 km2). By removing background winds calculated by ERA5 data and successfully recording the lake-land breeze cycle, we devised a succinct and effective approach for distinguishing lake-land breezes. Lake-land breeze had a high annual occurrence frequency of 13.4%–24.7% and a yearly mean lake-breeze speed of 1.6 m/s and yearly mean lake-breeze duration of 4.8 h; spring has the highest frequency and summer has the lowest frequency because of the greater thermal differences between lake and land in spring. The lake breeze mostly started at 06:00–07:00 and 10:00–13:00 (LST), showing a double-peak pattern, and ended at 17:00–19:00 (LST). On the other hand, the land breezes mainly started at 00:00–01:00 (LST) and ended at 05:00–06:00. The distance between each station and the lake has a negative correlation to the frequency and duration of the lake-land breeze, showing the higher frequency and duration at the near stations and the lower frequency and duration at the stations far from the lake. The land breeze has similar spatial characteristics. Winter has relatively lower seasonal average wind speeds of the lake breeze at most stations; spring and winter have high average wind speeds of the land breeze at each station, while summer and autumn have low. The study of the city lake's lake-land breeze will shed new insights into addressing the urban layout.

Does salinization impact long‐term Daphnia assemblage dynamics? Evidence from the sediment egg bank in a small hard‐water lake

Salinization of freshwater ecosystems threatens global aquatic biodiversity. There is a need for studies that follow populations in situ during salinization to understand the effects on species and ecosystems. We follow 170 years of Daphnia dynamics in the sediment ephippia archive of a small urban lake near St. Paul, Minnesota, to characterize effects of severe recent salinization on lake Daphnia. We found modest changes in the flux of ephippia in this lake; all three key Daphnia functional groups remained in the assemblage throughout the period of salinization. Reconstruction of the size distribution of Daphnia pulicaria demonstrated a consistent increase in body size in opposition to the expected trajectory during salinization. Our findings highlight that in hard‐water lakes, the effects of salinization are nuanced and require further investigation to better understand overall impacts of salinization on hard‐water lake Daphnia assemblages.

Occurrence and depositional history of organochlorine pesticides in the sediments of the Zayandehrud River in the arid region of Central Iran

In this study, surface sediments along the Zayandehrud River (14 samples), and two dated core sediments (46 samples) from small artificial urban lakes at the middle section of the Zayandehrud River in the Gavkhooni basin in the central arid regions of Iran were analyzed for residual levels of 20 organochlorine pesticide (OCP) compounds. Total OCP concentrations ranged from 0.1 to 50.1 ng g-1 dry weight and from 1.9 to 51.5 ng g-1 dry weight in surface and core sediments, respectively. Dichlorodiphenyldichloroethylene (DDE) and dichlorodiphenyldichloroethane (DDD) were found to be the predominant OCPs in these sediments. The calculated metabolic and isomeric ratios confirmed the aged nature of residual dichlorodiphenyltrichloroethane (DDT) in sediments. Moreover, the isomeric ratios indicated the aged nature of technical HCH (hexachlorocyclohexane), while the contribution of γ- HCH (lindane) as a main source has increased, especially in the last two decades. Past usage, as well as current usage of endosulfan technical mixture in the Gavkhooni basin, has been found in the last four decades. Analyses of sedimentary cores, as natural archives, have shown the successful ban on the use of organochlorine pesticides (especially DDT) in the Gavkhooni basin, and to some extent, in the central plateau of Iran. In general, it can be concluded that natural factors (i.e., floods and wet years) lead to soil leachate and play an essential role in remobilization and transfer of residual OCPs from soil to inland aquatic ecosystems in the Gavkhooni basin, which is an arid region.

Environmental investments decreased partial pressure of CO2 in a small eutrophic urban lake: Evidence from long-term measurements

Inland waters emit large amounts of carbon dioxide (CO2) to the atmosphere, but emissions from urban lakes are poorly understood. This study investigated seasonal and interannual variations in the partial pressure of CO2 (pCO2) and CO2 flux from Lake Wuli, a small eutrophic urban lake in the heart of the Yangtze River Delta, China, based on a long-term (2000–2015) dataset. The results showed that the annual mean pCO2 was 1030 ± 281 μatm (mean ± standard deviation) with a mean CO2 flux of 1.1 ± 0.6 g m−2 d−1 during 2000–2015, suggesting that compared with other lakes globally, Lake Wuli was a significant source of atmospheric CO2. Substantial interannual variability was observed, and the annual pCO2 exhibited a decreasing trend due to improvements in water quality driven by environmental investment. Changes in ammonia nitrogen and total phosphorus concentrations together explained 90% of the observed interannual variability in pCO2 (R2 = 0.90, p < 0.01). The lake was dominated by cyanobacterial blooms and showed nonseasonal variation in pCO2. This finding was different from those of other eutrophic lakes with seasonal variation in pCO2, mostly because the uptake of CO2 by algal-derived primary production was counterbalanced by the production of CO2 by algal-derived organic carbon decomposition. Our results suggested that anthropogenic activities strongly affect lake CO2 dynamics and that environmental investments, such as ecological restoration and reducing nutrient discharge, can significantly reduce CO2 emissions from inland lakes. This study provides valuable information on the reduction in carbon emissions from artificially controlled eutrophic lakes and an assessment of the impact of inland water on the global carbon cycle.

Geochemistry features of sediments of small urban arctic Lake Komsomolskoye, Murmansk region

First data of geochemistry and mineralogy of recent sediments of small Lake Komsomolskoye located in Monchegorsk town from Murmansk region (Russia) are presented. The high concentrations of heavy metals were found in surface layers of researched lake sediments. The most accumulation level is initialled for copper and nickel, which are entered to lake from copper-nickel plant complex situated near the arctic town. Other metals also can enter to waterbody in result of activity of this factory complex. In addition, lead, cadmium, antimony, thallium and other elements may be products of the atmospheric transport of pollutants from industries of North and East Europe. Moreover, we have studied main fractions of heavy metals from upper layers of Lake Komsomolskoye and morphology and composition of technogenic particles of nickel, copper, iron and other metals. The origin of these particles is directly associated with the different stages of processing technology of nickel and copper ore on the copper-nickel plant complex (crushing, flotation, roasting, and smelting).

Vanadium as an indicator of the impact of fuel oiled thermal power plants on the environment: paleolimnological reconstructions

The article presents data on the behavior of vanadium in recent sediments from small urban lakes in the North of Russia. The works were carried out in Murmansk, Petrozavodsk and Monchegorsk. The main role in the entry of vanadium into the environment of these cities is played by emissions from thermal power plants operating on fuel oil.

Annual dynamics of water quality in a small urban landscape lake: a case study of Lake Wuzhou, China

Annual dynamics of water quality in a small urban landscape lake: a case study of Lake Wuzhou, China

NERACA AIR SITU CIKARET DAN SITU KABANTENAN DI KABUPATEN BOGOR MENGGUNAKAN PEMODELAN HIDROLOGI SWAT

Bogor regency which is located in the middle of the Ciliwung basin centered in Cibinong city is experiencing rapid urban development. However, with the rapid urban development, most of these small lakes in either disappear or in degraded conditions. In this area presently still maintain 95 urban small lakes or locally known as ‘situ’. Situ has multifunction such as water retention for flood mitigation, irrigation for urban agriculture, fisheries, water sport activities, and ecotourism. The objective of this study was to analyze the water balance of situ. The model was calibrated and validated on the Kampung Kelapa river gauge with manual calibration. The Soil Water Assesment Tool (SWAT) is a hydrological model designed to predict the impact of land use and management on water, sediment and agricultural chemical yields in watersheds, The model was applied to Situ Kabantenan and Cikaret for modeling of the hydrological water balance. The SWAT model simulation was done for the periods of 2008–2015 while it used land use information in 2014. The Calibration was done in 2014 and the validation in 2013, the R2 and Nash Sutcliffe Efficiency (NSE) of the calibration were 0,58 and 0,55 respectively and the validations were 0,54 and 0,49 respectively. The monthly average of volume of Situ Kabantenan and Situ Cikaret from the simulation were 136,955 m3 and 508,907 m3, respectively. The annual inflow of Situ Cikaret was 24,693,822 m3/year and outflow was 25,177,593 m3/year, precipitation was 648,520 m3/year, evaporation was 166,543 m3/year, delta storage 1,794 m3/year, respectively. The average inflow discharge of Situ Cikaret (2008–2015) were 0.78 m3/s and outflow discharge was 0.80 m3/s. The water balance results showed that both sites were in good condition since they have never passed the emergency spillway, but their function needs to be optimized as a flood controller in the Ciliwung Watershed. This study also showed that the SWAT model can be utilized as a potential monitoring tool, especially for small urban lakes as water reservoirs.

An Automatic Monitoring System for High-Frequency Measuring and Real-Time Management of Cyanobacterial Blooms in Urban Water Bodies

Urban lakes mitigate the negative impacts on the hydrological cycle and improve the quality of life in cities. Worldwide, the concern increases for the protection and management of urban water bodies. Since the physical-chemical and biological conditions of a small aquatic ecosystem can vary rapidly over time, traditional low frequency measurement approaches (weekly or monthly sampling) limits the knowledge and the transfer of research outcomes to management decision-making. In this context, this paper presents an automatic monitoring system including a full-scale experimental site and a data transfer platform for high-frequency observations (every 5 min) in a small and shallow urban lake (Lake Champs-sur-Marne, Paris, France, 10.3 ha). Lake stratification and mixing periods can be clearly observed, these periods are compared with the dynamic patterns of chlorophyll-a, phycocyanin, dissolved oxygen and pH. The results indicate that the phytoplankton growth corresponds with dissolved oxygen cycles. However, thermal stratification cannot totally explain the entire dynamic patterns of different physical-chemical and ecological variables. Besides, the cyanobacteria is one of the dominating groups of phytoplankton blooms during the lake stratification periods (8 August–29 September 2016). During the cooling mixed period (29 September–19 October 2016), the high concentration of chlorophyll-a is mainly caused by the other phytoplankton species, such as diatoms. Perspectives are discussed in order to apply this observation system for real-time management of water bodies and lakes.

THE GEOCHEMICAL SPECIFICS OF MODERN SEDIMENTATION PROCESSES ON THE BOTTOM OF A SMALL LAKE LAMBA UNDER TECHNOGENIC IMPACT

The data on the chemical composition of bottom sediments of the small urban Lake Lamba located in the city of Petrozavodsk (Republic of Karelia) are presented. In this investigation we used modern precision methods for studying matter. Chemical analysis of bottom sediments of Lake Lamba was conducted using X-ray fluorescence spectrometer ARL ADVANT'X and mass spectrometer XSeries-2 ICP-MS. It was established that sediments in the lake are ferruginous (limonite) sapropels with a high content of organic matter. It is shown that the distribution of heavy metals and their accompanying microelements in the studied freshwater sediments reflects the industrial history of the city of Petrozavodsk and the general man-generated pollution in anthropogenically disturbed territories of the world. The distribution of V, Cr, Ni concentrations in the bottom sediments indicates a significant influence of the Petrozavodsk heating plant. The abnormally high Pb concentrations in the sediment layers are associated with global pollution of the environment by this heavy metal due to its input from traffic emissions. The distribution of Co, Cu, Zn, Mo, W concentrations reflects the impact of industrial enterprises in Petrozavodsk on the ecosystem of Lake Lamba.

Phytophilous Fauna of a Small and Artificial Urban Lake

Abstract Phytophilous community on Myriophyllum spicatum was studied in a small artificial urban lake in the city of Osijek (eastern Croatia), during the spring and summer season in 2010. In the eutrophic conditions, macrophyte stands were well developed and in the formed periphyton representatives of the following invertebrate taxa were found: Hydrozoa, Nematoda, Gastropoda, Cladocera, Copepoda, Insecta larvae - including families Chironomidae and Coleoptera. They displayed differences in temporal abundance patterns. Two separate phases in macrophyte colonization with differences in invertebrate composition and abundance were recorded. Insect larvae, particularly Chironomidae, were most abundant in the first phase, through the spring period, and Hydra oligactis (brown hydra) was most abundant in the second phase, i.e. summer period. Concurrently, microcrustacean abundance declined towards the end of the summer. Results of the analyses indicated that water temperature and perihyton biomass were the variables exerting the main influence on the invertebrate assemblage, while interestingly, macrophyte size and biomass were negatively correlated with most of the fauna abundance. On the other hand, brown hydra was negatively correlated with all other invertebrate taxa, except gastropods. Larger surface of submersed macrophytes is the main parameter supporting the increase of invertebrate abundance due to providing protection from predators and growth for periphyton, an important food source for these phytophilous organisms. Macrophyte length was positively correlated with Hydra abundance, while Chironomids were more influenced by periphyton biomass. These organisms can indicate water quality conditions and a potential increase in primary and secondary production.

城市小型湖泊浮游植物群落结构特征及演替规律——以武汉沙湖为例

PDF HTML阅读 XML下载 导出引用 引用提醒 城市小型湖泊浮游植物群落结构特征及演替规律——以武汉沙湖为例 DOI: 10.5846/stxb201606211215 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金（41331174）；江西省水利厅重大科技项目（KT201412）；水利部科技推广项目（TG1520） Distribution and succession pattern of phytoplankton communities in a small urban lake, Sand Lake in Wuhan City, China Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:城市小型湖泊具有对环境变化的高敏感性，其浮游植物群落特征和演替规律对湖泊生态系统的监测与管理有重要意义。本研究于2015年3-12月，对武汉市沙湖进行了生态和水质监测，共鉴定出藻类10门312种，绿藻、硅藻和蓝藻种类数占优。为探究富营养化城市小型湖泊浮游植物群落时空异质性及其演替驱动力，选取了4个多样性指数（Shannon-Wiener指数、Simpson指数、Pielou均匀度指数和Whittaker指数），并进行了多样性指数与环境因子的相关性分析、主成分分析和聚类分析，计算了优势种在监测时段的3个种间联结性指数和校正χ2检验系数。结果表明，夏秋季节浮游植物群落处于演替的稳定状态，环境因子驱动作用明显，其中离子浓度的影响大于温度的影响，钠、镁离子浓度为主要影响因素；蓝藻门和绿藻门优势种联结性较高，硅藻门优势种内部联结性较高而与其他门类相关性较低，从季节上看，夏秋季节的优势种种间联结性较高，春冬季优势种与其他时段优势种相关性低，可能为群落在冬春季不稳定的原因。 Abstract:Small urban lakes are highly sensitive to changes in their environment and are closely associated with the surrounding urban systems. The distribution and succession pattern of phytoplankton can significantly influence the entire ecosystem in a small urban lake. From March to December 2015, phytoplankton and water quality were monitored in Sand Lake, Wuhan city, China. In total, 312 species were detected representing 10 phyla, with Chlorophyta, Bacillariophyta, and Cyanophyta being the major phyla represented. Biodiversity indices were calculated using the methods of Shannon-Wiener, Simpson, Pielou, and Whittaker. The biodiversity indices and environmental factors were subjected to correlation analysis, principal component analysis, and cluster analysis. Three interspecific association indices and the calibrated coefficients of χ2 test were calculated. The results showed that the phytoplankton reached a stable state in summer and autumn, during which the environmental factors were the main influence; the effect of constant ion concentration was greater than that of temperature, particularly those of sodium and magnesium. Analysis of the data for the dominant species showed that Chlorophyta and Cyanophyta were significantly correlated, whereas Bacillariophyta showed no significant correlation with other phyla. A significant correlation occurred between summer and autumn dominant species, while dominant species in winter and spring showed no significant correlation with those in other seasons, which could be attributed to the low stability of the phytoplankton during this period. 参考文献 相似文献 引证文献

Seasonal influence of environmental variables and artificial aeration on Escherichia coli in small urban lakes.

This study investigated patterns of Escherichia coli in urban lakes in Lubbock, Texas. Specific objectives were to (1) document seasonal patterns in abundance of E. coli over a 3-year period, (2) identify environmental factors, including effects of migratory geese and artificial aeration devices that may influence E. coli abundance, and (3) determine if E. coli abundance over time was similar for individual lakes. Water samples were collected monthly for 36 months from six lakes, three of which contained artificial aeration devices (fountains). Regression models were constructed to determine which environmental variables most influence E. coli abundance in summer and winter seasons. Escherichia coli is present in the lakes of Lubbock, Texas year-round and typically exceeds established bacterial thresholds for recreational waters. Models most frequently contained pH and dissolved oxygen as predictor variables and explained from 17.4% to 92.4% of total variation in E. coli. Lakes with fountains had a higher oxygen concentration during summer and contained consistently less E. coli. We conclude that solar irradiation in synergy with pH and dissolved oxygen is the primary control mechanism for E. coli in study lakes, and that fountains help control abundance of fecal bacteria within these systems.

Three-year survey of abundance, prevalence and genetic diversity of chlorovirus populations in a small urban lake.

Inland water environments cover about 2.5 percent of our planet and harbor huge numbers of known and still unknown microorganisms. In this report, we examined water samples for the abundance, prevalence, and genetic diversity of a group of infectious viruses (chloroviruses) that infect symbiotic chlorella-like green algae. Samples were collected on a weekly basis for a period of 24 to 36months from a recreational freshwater lake in Lincoln, Nebraska, and assayed for infectious viruses by plaque assay. The numbers of infectious virus particles were both host- and site-dependent. The consistent fluctuations in numbers of viruses suggest their impact as key factors in shaping microbial community structures in the water surface. Even in low-viral-abundance months, infectious chlorovirus populations were maintained, suggesting either that the viruses are very stable or that there is ongoing viral production in natural hosts.