共查询到20条相似文献，搜索用时 31 毫秒
1.
Transplantation of artificial panels between a polluted and an unpolluted site was used to evaluate eutrophication effects on the development of fouling communities in Ilha Grande Bay, SE Brazil. Organic pollution changed the relative dominance of species in the fouling communities of transplanted panels, although, their richness, evenness, and specific composition did not change. The chlorophyte Ulva sp. occurred only in the polluted site and in panels transplanted to it, whereas the bryozoan Aetea lingulata was found only in the unpolluted site and in panels transplanted to this site. These species are therefore good pollution indicators. The best pollution indicators, however, were amphipods and Spionidae polychaetes which formed mucous tubes. These groups had significantly higher values of percent cover (p<0.0001) in the polluted site and in panels transferred to it. The dominance shift is the first evidence that more meaningful changes can occur in the structure of fouling communities on a long-term scale. 相似文献
2.
The impact of the wastewater input of Médiouna agglomeration (southeastern area of Casablanca) on the diatom flora and water quality of Oued Hassar stream (Morocco) was studied from July 1997 to August 1998. This wastewater effluent, which was highly loaded with ammonia, orthophosphates and organic matters, had disturbed the diatom assemblages structure and water quality of this stream.The study of the epilithic algal assemblages revealed the presence of 130 taxa of diatoms, 21 of which, according to the available literature, were recorded for the first time in the Moroccan inland waters. Almost all the latter taxa are mesohalobic or oligohalobic-indifferent. Nitzschia inconspicua Grun. was the most abundant species (47.7%) and grows particularly at the source of the stream. Navicula subminuscula Manguin, Nitzschia capitellata Hust. and Nitzschia desertorum Hust. have their dominance in the highly polluted zones, especially downstream the wastewater input. 相似文献
3.
《Limnologica》2016
Diatom based biomonitoring tools are proven to be a practical way to indicate stream conditions, but only little is known how stable diatom inferred stream classifications are in time. We studied annual variation in diatom community–environment relationships, community structure and diatom indices (Index of Pollution Sensitivity, IPS and Trophic Diatom Index, TDI) during three consecutive years (2010–2012) in four drainage basins distributed in Finland. We also used a cluster analysis to examine if stream classifications resulted in distinct and temporally stable community types. We found only subtle temporal variation in community–environment relationships, nutrient concentrations (N, P) and conductivity consistently being the main factors structuring communities. According to Mantel tests, diatom communities resembled each other significantly at different years, and the values of IPS and TDI indices remained relatively stable in the basins through time. The stream classification based on diatoms also resulted in temporally stable and statistically distinct community types. We thus suggest that sampling of diatoms, e.g., in every three years seems to be a reliable procedure to assess biological water quality. Generally, to choose the correct metrics to assess water quality is essential, and both biological and physicochemical factors should be considered. 相似文献
4.
Desalinization effects on benthic diatom communities were investigated in two adjacent streams in Northern Thuringia, the creek Urbach and the river Helbe. Salt-saturated stockpile effluents had been introduced into the Urbach until 1996, resulting in fluctuating chloride concentrations with maximum values up to 25.4 g · 1−1 (Helbe: max. 3.7 g · 1−1).
The diatom vegetation and hydrographical and chemical data of an Urbach site were compared to those of a sampling site further downstream. Monthly sampling in 1996 started at the end of salt influx in January. Reference samples from the years 1995, 1986 and 1963 were evaluated along with the 1996 samples.
After termination of the introduction of salt-loaded effluents, relative abundances of brackish water species greatly decreased within three months. The Halobion Index (Ziemann 1982), reflecting osmotic and ion composition effects on diatoms, decreased until May 1996, then stabilized. In summer 1996, several diatoms had a mass development, showing that salinization impacts had previously overruled effects of other environmental variables. 相似文献
5.
6.
《Limnologica》2020
Headwater streams are interesting ecological systems for studies of metacommunities given their high degrees of isolation, unidirectionality of water flow and hierarchical organization in the drainage network. In addition, for passively dispersing aquatic organisms (e.g. planktonic diatoms), connectivity between sites is unidirectional, which implies a higher isolation of headwaters, leading to a greater dispersal limitation between streams. The aim of this study was to evaluate the relative importance of local environmental (i.e., physicochemical variables) and spatial (i.e., distance between sites) components to the planktonic diatom community in 28 headwater streams of the Cerrado, central region of Brazil. Due the fact that each sampling point was located in a different headwater stream, we expected that spatial components (a proxy for diatom dispersal) were more important than local environmental conditions to the structure of the diatom metacommunity. We found 51 morphospecies of diatoms (Bacillariophyceae). The community composition of diatoms showed strong spatial variation, which was also indicated by high beta diversity (mainly contributed by the turnover component). The variation in diatom community composition, species richness, total density, and Local Contribution to Beta Diversity (LCBD) of headwaters streams was explained solely by spatial factors. Based on these results, we inferred that due to dispersal limitation, the diatom communities of these headwaters tend to show distinct species composition, with high species turnover among the local communities. We highlight the importance of headwater streams as reservoirs of biodiversity for a riverine diatom metacommunity. 相似文献
7.
硅藻群落结构的差异:比较样本采集过程与空间梯度 总被引：1，自引：0，他引：1
硅藻种群的分布与其所处的生境条件密切相关,但在实际过程中的一些人为因素,例如取样方法、样本的制备以及藻种鉴定都可能会干扰到种群结构的分析结果.因此很有必要探究这些人为因素是否会对真实的硅藻群落生态学研究产生误导性的判断,以免干扰硅藻生物水质评价的客观性.选取采样方法及样本制备为代表的人为因素对硅藻群落生态分析结果引入的误差大小进行评估.结果显示,子样本之间(同一样品重复制作的玻片样本)和样品之间(同一样点重复取样)群落结构差异大小分别是1.26%和1.97%,同一条河流的样点之间则为3.38%,而所选定的跨河流研究区域的样点间群落结构差异最大(42.03%).生态学的排序结果和数理统计分析表明,在硅藻群落结构分析中,现场取样方法和样本制备过程相对于不同生境条件所引起的变化,并不会带来较大的差异.因此在河流附生硅藻的群落生态学研究中,可基本不考虑取样方法等因子的干扰,而是侧重于环境因子对硅藻生态分布的影响. 相似文献
8.
东江惠州河流段人工基质附着硅藻群落的季节性动态 总被引：3，自引：0，他引：3
硅藻群落结构特征是反映河流水生态状态的重要生物指标,但我国多数河流中还缺少硅藻种类组成与季节变化的基本数据.2010年用瓷砖片作为人工基质研究东江惠州河流段附着硅藻群落结构的季节性变化,共鉴定出附着硅藻40属153种(包括亚种和变种),主要的优势属有曲壳藻属(Achnanthidium)、异极藻属(Gomphonema)、直链藻属(Melosira)、舟形藻属(Navicula)、菱形藻属(Nitzschia)、脆杆藻属(Synedra)等.Gomphonema parvulum和Nitzschia palea为该河流段的广泛性藻种,且相对丰度的季节性变化明显.RDA分析表明,水温、DO、NH4+-N、PO34--P、电导率、pH值等对附着硅藻群落结构有重要影响.在丰水期,水量对于运动能力较强的N.palea的相对丰度具有明显的影响. 相似文献
9.
L. C. Rai 《洁净——土壤、空气、水》1980,8(6):561-567
A general survey of the various polluted environs e.g., (i) The cement factory, (ii) The aluminium factory; (iii) The fertilizer factory; (iv) Dairy waste, and (v) Township sewage, has been made with a view to studying the distribution, dominance and diversity of algal communities growing therein. This study has revealed that the algal community structure along with physico-chemical factors can be best used for the assessment of water pollution. Oscillatoria has been found dominant in all those polluted environs containing a high amount of nitrogen and phosphorus, thereby indicating that this alga is tolerant to organic pollution. However, a sparse vegetation of algae as recorded in other situations is indicative of either a poor nutrient status of the habitat or the presence of some growth inhibitory substances. 相似文献
10.
Diatom communities are influenced by environmental perturbations, such as the monsoon system that impact the niche opportunities of species. To discern the influence of the monsoon system on diatom community structure, we sampled during two consecutive post-monsoons (2001 and 2002) and the intervening pre-monsoon at Mumbai and Jawaharlal Nehru ports along the central west coast of India. Characteristic temporal shifts in diatom community structure were observed across the sampling periods; these were mainly driven by temperature, salinity and dissolved oxygen saturation. The nutrient-poor pre-monsoon period supported low abundance yet high species richness and diversity of diatoms. Coscinodiscus, Cyclotella, Thalassiosira, Triceratium, Pleurosigma, Skeletonema and Surirella were the most dominant genera. Both the post-monsoon periods, following dissimilar monsoon events, were dominated by Skeletonema costatum, but differed in some of the residual species. Thalassiosira and Thalassionema spp. dominated mostly during post-monsoon I whereas Triceratium and Pleurosigma spp. dominated during post-monsoon II. To understand the underlying ecological mechanisms involved in such dynamics, we focus on the dominant diatom species in post-monsoon periods, S. costatum, that contributes up to 60% to total diatom cell numbers. This research is relevant in light of the fluctuating monsoon regimes over the Asian continent, the confounding effects of anthropogenic eutrophication and the resulting cascading effects on trophic web dynamics. 相似文献
11.
The current state of the Ingoda River ecosystem is assessed. The orographic features, economic development, the structure of aquatic organism communities, and water quality allow the authors to substantiate the division of the river ecosystem into four areas for more sound water management. General estimation of the Ingoda water quality in different sites have shown that the river’s water is clearing its upper reaches, moderately polluted upstream of Chita, heavily polluted downstream of the city, and polluted downstream of Karymskaya Station. 相似文献
12.
Salt-loaded effluents were introduced into the river Wipper during the mining period for almost a century. Beginning with the year 1990, the waste water load was strongly reduced due to the termination of the potash industry. Prior to 1990, monthly means of the chloride concentrations at times exceeded 6,000 mg l−1 in the strongly polluted sections. Maximum concentrations reached twice these values. Up to 1998, mean annual chloride concentrations decreased to values below 2,000 mg l−1. This led to more balanced fluctuations in salinity which had been pronounced before, depending on discharge and short-term changes in production. Similarly, the physiologically adverse ion conditions improved due to decrasing potassium and increasing calcium proportions.
In 1963/64, 1986 and 1998, samples of epilithic, epiphytic and epipsammic diatoms were taken at locations of different salinities along the river and examined for the effects of the salinization on the structure of the diatom assemblages. These structures changed in dependence on salinity. Increasing salt concentrations coincided with decreasing oligohalophilic and increasing mesohalophilic and polyhalophilic species numbers. Above a chloride concentration of about 3,000 mg l−1, the proportion of the latter exceed that of the former (halobion index > 50). Corresponding to different conditions of salinization along the river, characteristic diatom assemblages occur differring from each other and which are specific for the river section. Spring and autumn aspects of the diatom assemblages show also salt-dependent differences. The assemblages found in 1998 after decrease of salinization have changed markedly in comparison to those from 1963/64 and 1986. Halobiontic species predominating formerly occurred only occasionally or not at all. They were replaced by oligohalobic-indifferent forms.
An ecological assessment of the changes was performed based on the halobion index calculated from all the samples. For the strongly salinized section of the river Wipper, a shift from -mesohalobic/polyhalobic conditions in 1963/64 and 1986 to -oligohalobic/β-mesohalobic conditions in 1998 was found. However, constant -oligohalobic conditions are still not given. With regard to the transition from -oligohalobic (limnetic) to β-mesohalobic (brackish) conditions, a maximum chloride concentration of 600 mg l−1 was found. To guarantee -oligohalobic conditions, a maximum chloride concentration of 400 mg l−1 should not be exceeded. 相似文献
13.
Susanne C. Schneider A.E. LawniczakJ. Picińska-Faltynowicz K. Szoszkiewicz 《Limnologica》2012,42(3):204-211
We analyzed species composition and abundance of macrophytes, diatoms and non-diatom benthic algae, water chemistry and habitat structure of 24 river sites in Poland, in order to better understand which parameters structure macrophyte and benthic algae communities. Community patterns for macrophytes and diatoms are most closely related, while macrophytes and non-diatom benthic algae have the weakest relationship. Environmental parameters best explaining community patterns are channel substrate parameters for non-diatom benthic algae, and a combination of channel substrate and river bank characteristics for submerged macrophytes, emergent macrophytes and diatoms. Among the organism groups investigated, the diatom community pattern is best correlated to the environmental data similarity matrix. We hypothesize that the results can be explained by the shorter generation time of diatoms compared to macrophytes, and by a higher dispersal rate of diatoms compared to macrophytes and non-diatom benthic algae. This has several practical consequences for bioindication: (1) Diatoms are usually the organism group most closely following environmental parameters, for both increasing and decreasing impact. (2) Since the biotic indices developed for the Water Framework Directive are meant to primarily indicate ecological changes, not water chemistry, the nature of diatoms to closely reflect water chemistry is not necessarily advantageous. (3) The applicability of macrophyte and probably also non-diatom benthic algae indices is more locally restricted, while diatom indices are applicable to greater areas. (4) In ecosystems which are subject to changing environmental conditions, differences in biotic indices between macrophytes, diatoms and non-diatom benthic algae are to be expected. These differences could provide information relating to ecosystem stability. (5) In stable ecosystems, analyzing one of the three organism groups “diatoms”, “non-diatom benthic algae” and “macrophytes” will be sufficient to characterize the quality element “macrophytes and phytobenthos”, as required by the Water Framework Directive. However, in ecosystems subject to increasing pressure, macrophytes likely will have a tendency to indicate “too good”, while in ecosystems subject to decreasing pressure, diatoms will have a tendency to indicate “too good”. 相似文献
14.
藻类是湖泊生态系统中重要的初级生产者,物种多样性高且对水环境变化敏感,其生产力水平与群落构建模式是反映湖泊环境梯度和生态系统特征的可靠指标。其中硅藻优势属种的演替模式及其环境条件识别,是开展湖泊生态健康和环境质量评价的重要内容。本文选择亚热带地区浅水湖泊异龙湖开展季节调查,对20个采样点的叶绿素a和硅藻群落组成等指标开展分布特征及其驱动因子的定量评价,系统分析藻类变化的时空模式、驱动因子及其指标异同。2020年12月一2021年9月,异龙湖水环境特征的季节波动明显,综合营养指数TSI平均为74.76,总体处于富营养水平。在80个水体样品中共发现硅藻21属68种,群落结构以浮游类型(平均占比79.33%±20.69%)的耐中富营养种为主;在4个季节的调查中,膜糊直链藻Aulacoseira ambigua(61.62%±20.26%)为优势种。主成分分析显示,硅藻群落组成存在明显的空间差异和季节变化。冗余分析和方差分解等结果表明,水体营养因子(TN、TP和N:P)是影响叶绿素a浓度空间变化的重要因子(解释方差为19.08%±11.4%),水温和水深梯度的影响较小(9.63%±11.31%... 相似文献
15.
Downstream effects of stream flow diversion on channel characteristics and riparian vegetation in the Colorado Rocky Mountains,USA 
下载免费PDF全文
下载免费PDF全文 Simeon T. Caskey Tyanna S. Blaschak Ellen Wohl Elizabeth Schnackenberg David M. Merritt Kathleen A. Dwire 《地球表面变化过程与地形》2015,40(5):586-598
Flow diversions are widespread and numerous throughout the semi‐arid mountains of the western United States. Diversions vary greatly in their structure and ability to divert water, but can alter the magnitude and duration of base and peak flows, depending upon their size and management. Channel geometry and riparian plant communities have adapted to unique hydrologic and geomorphic conditions existing in the areas subject to fluvial processes. We use geomorphic and vegetation data from low‐gradient (≤3%) streams in the Rocky Mountains of north‐central Colorado to assess potential effects of diversion. Data were collected at 37 reaches, including 16 paired upstream and downstream reaches and five unpaired reaches. Channel geometry data were derived from surveys of bankfull channel dimensions and substrate. Vegetation was sampled using a line‐point intercept method along transects oriented perpendicular to the channel, with a total of 100 sampling points per reach. Elevation above and distance from the channel were measured at each vegetation sampling point to analyze differences in lateral and vertical zonation of plant communities between upstream and downstream reaches. Geomorphic data were analyzed using mixed effects models. Bankfull width, depth, and cross‐sectional area decreased downstream from diversions. Vegetation data were analyzed using biological diversity metrics, richness, evenness and diversity, as well as multivariate community analysis. Evenness increased downstream from diversions, through reduced frequency of wetland indicator species and increased frequency of upland indicator species. Probability of occurrence for upland species downstream of a diversion increases at a greater rate beginning around 0·5 m above active channel. The results suggest that channel morphology and riparian plant communities along low‐gradient reaches in montane environments in the Colorado Rocky Mountains are impacted by diversion‐induced flow alteration, with the net effect of simplifying and narrowing the channel and homogenizing and terrestrializing riparian plant communities. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
16.
Impact of stress and disturbance factors on the phytoplankton communities in Northeastern Brazil reservoir 总被引：1，自引：1，他引：0
Naithirithi T. Chellappa Thiago Chellappa Fabiana R.A. Cmara Odete Rocha Sathyabama Chellappa 《Limnologica》2009,39(4):273-282
The ecology of phytoplankton reservoir communities plays a pivotal role in their management and in the development of inland fisheries in the water scarce semi-arid regions of Rio Grande do Norte State, Brazil. The hydrological conditions characterizing these reservoirs include infrequent rainfall and high evaporative loses. The phytoplankton assemblages in tropical climate are structured primarily on dry and wet cycles, not the annual temperature and light regime. The purpose of the current study was to investigate the ecological aspects of phytoplankton communities from three reservoirs during the period of July 2003–June 2004, which include atypical summer rainfall and reservoir overflow. The environmental data broadly divided into two categories, stress factors and disturbance factors. The stress factors deals with the impact of high particulate organic matter and low dissolved oxygen concentrations and disturbance factors, linked to water level fluctuation through flushing and reservoir drawdown, and these events are associated with the phytoplankton assemblages. Results indicated that the three distinct hydroperiods determined the structure of phytoplankton and chlorophyll levels and limited the presence and relative abundance of cyanobacterial species. Phytoplankton succession accompanied changes in clear and turbid water phase represented by the alternate dominance between diatoms and chlorophytes. Inundation and complete filling of reservoir stimulated “s” and “r” strategists species (<20 um) of unicellular and some colonial members of chlorophytes and cryptomonads in highly turbid water environment, and “c” strategist species in rest of the wet period following disturbance gradients. Statistical analysis elicited a significant relationship between particulate organic matter and relative abundance of smaller chlorophytes, which was deemed as stress factor. The flushing and reservoir drawdown indicate disturbance gradient and as a consequence high diversity. Furthermore, a substantial reduction in chlorophyll levels was registered in turbid water phase is related to the reduction of light penetration and re-suspension of sediments. Considering these results, it can be suggested that the well-managed reservoir drawdown can possibly maintain an environment free of eutrophication and cyanobacterial dominance. 相似文献
17.
This study examined the effects of anthropogenic contaminants and environmental variables on the composition of benthic diatom communities within a contaminated bay adjacent to an abandoned waste disposal site in Antarctica. The combination of geographical, environmental and chemical data included in the study explained all of the variation observed within the diatom communities. The chemical data, particularly metal concentrations, explained 45.9% of variation in the diatom communities, once the effects of grain-size and spatial structure had been excluded. Of the metals, tin explained the greatest proportion of variation in the diatom communities (28%). Tin was very highly correlated (R2>0.95) with several other variables (copper, iron, lead, and sum of metals), all of which explained similarly high proportions of total variation. Grain-size data explained 23% of variation once the effects of spatial structure and the chemical data had been excluded. The pure spatial component explained only 1.8% of the total variance. The study demonstrates that much of the compositional variability observed in the bay can be explained by concentrations of metal contaminants. 相似文献
18.
Vlahogianni T Dassenakis M Scoullos MJ Valavanidis A 《Marine pollution bulletin》2007,54(9):1361-1371
Mussels are used as sentinel organisms and bioindicators to evaluate the toxic effects of chemical pollutants in marine organisms, especially heavy metals, representing an important tool for biomonitoring environmental pollution in coastal areas. Antioxidant defence enzymes play an important role in cellular antioxidant defence systems and protect from oxidative damage by reactive oxygen species (ROS). Indigenous mussels Mytilus galloprovincialis of the Saronikos Gulf of Greece were used for monitoring heavy metal pollution in three polluted sites in the area and in one unpolluted site. Seasonal variations of the activity of antioxidant defence enzymes, superoxide dismutase (SOD) and catalase (CAT), as well as lipid peroxidation (LP) were measured as biomarkers in a period of three years in relation to concentrations of trace metals in their gills and mantle and compared to mussels from an unpolluted sampling site. SOD activity increased at least 2 fold at the polluted sites when compared to the control site (the high activity was recorded in the spring time). CAT activity was increased 2-3 times at the polluted sites, with high activity in the winter and spring time, compared to the control site. LP concentration was twice higher at the polluted sites, following the same seasonal pattern. Trace metals contents in mussels collected at polluted sites were 3-4 fold higher compared to the control site and showed moderate variations along the months, with a winter maximum followed by a summer pre-spawning minimum matching the seasonal trends of temperature and salinity. Our results showed that metal pollution in the Elefsis Bay (the most polluted coastal area) causes relatively medium levels of oxidative stress in tissues of mussels due to cellular oxy-radical generation. This study, which is the first in the area, showed that seasonal variations of the activity of antioxidant defence enzymes and LP concentrations in mussels can be used as potential biomarkers of toxicity for long-term monitoring in marine coastal ecosystems. 相似文献
19.
Molecular analysis was applied to characterize bacterial community structure in sediment samples collected from pristine site and oil-polluted Black Sea harbor. Amplified Ribosomal DNA Restriction Analysis (ARDRA) revealed a high similarity in the restriction patterns of both samples thus not demonstrating the effect of the pollutant on the structure of the bacterial communities. Constructed 16S rRNA gene libraries gave more detailed assessment of members. Results showed that α- and γ-Proteobacteria were dominant in the oil polluted site, whereas the pristine site was characterized by prevalence of Actinobacteria. The biodegradative potential of the adapted bacterial community in the oil-polluted sediments was demonstrated by the presence of the aromatic ring hydroxylating dioxygenase genes. 相似文献
20.
N. Wu T. Tang X. Fu W. Jiang F. Li S. Zhou Q. Cai N. Fohrer 《Aquatic Sciences - Research Across Boundaries》2010,72(1):117-125
The ecological effects of small run-of-river dams on aquatic ecosystems are poorly understood, especially on downstream benthic
algal communities. We examined impacts of such dams on the benthic diatom community at a regional scale in the Xiangxi River,
China. A total of 90 sites were visited, which were divided into five habitats (H1–H5) according to impact extent of each
dam. Using partial least squares (PLS) modeling, we developed two predictive models (diatom species richness and total diatom
density) based on environmental variables of an unregulated habitat (H1). These models were then used to predict species richness
and total densities at impacted habitats (H2–H5) and residuals, i.e. the differences between observed and predicted values,
were used to evaluate impact strength of flow regulation. Significant impacts of flow regulation on diatom species richness
were detected at three impacted habitats (H3–H5), where observed species richness were significantly higher—70.6, 63.9 and
46.6%, respectively—than predicted values. Then, possible mechanisms for observed impacts were discussed. Further research
is necessary to address the potential negative impacts of cascade run-of-river dams on other aquatic organisms in different
seasons, and to explore more appropriate mechanisms for such impacts, which may lead to sustainable management strategies
and help to determine the optimal ecological water requirement for the Xiangxi River. 相似文献