Effect of eutrophication on culm architecture of lakeshore Phragmites reeds

The eutrophication of lakes in central Europe has been assumed to be at least partly responsible for a widespread die-back of fringing Phragmites australis reeds. To test the ‘eutrophication hypothesis’ on a broad data basis, lakeshore reed stands at 41 lakes of known trophic status and 10 stands in waste water and sludge treatment plants in Denmark and north Germany (North data subset, n=26), and south Germany, Switzerland and Austria (South data subset, n=25) were investigated. A total of 24 culm performance variables in three different shoot classes were analyzed by two-way ANOVA with the geographic origin and the ‘relative trophic index’ as factors. The geographic origin had a pronounced influence on culm architecture, whereas the effect of the trophic level mostly failed to be significant in the ANOVA. The culms from the North reed stands showed a weaker performance throughout than those from the South stands for a given trophic level. However, some of the morphometric traits in the North stands were significant positively correlated with the trophic level but very few significant cases were observed in the South data subset. Three hypotheses are discussed to explain the geographic effect: climatic effects, geochemistry of lake water and sediments, and trophic history of the lakes. It is concluded that lake eutrophication does not influence the culm performance negatively and that eutrophication cannot be regarded as a general cause in reed decline.     

气候变化与人类活动双重驱动的冷水湖泊富营养化

富营养化对水生生态系统造成的负面影响已在世界范围内广泛发生,尤其对淡水水源地湖泊的水环境质量影响深远,进而引起当地居民的饮用水安全与健康隐患。在人类活动和气候变化的双重驱动下,富营养化辐射的范围不断扩大,从过去主要集中于温带大型浅水湖泊已经扩展到寒冷地区的冷水湖泊。分析了近年来世界范围内高寒地区冷水湖泊富营养化的趋势特征与研究进展,探讨了气候变化、人类干扰(农业活动、畜牧业生产、管理措施不当等)在不同地区冷水湖泊富营养化进程中的作用。在未来的研究中,应进一步加强对冷水湖泊富营养化机制的探讨,并对已有富营养化症状的湖泊进行生态修复,以确保冷水湖泊生态系统健康并改善饮用水源地的环境质量。     

Maximum growing depth of macrophytes in Loch Leven,Scotland, United Kingdom,in relation to historical changes in estimated phosphorus loading

Eutrophication is common in shallow lakes in lowland areas. In their natural state, most shallow lakes would have clear water and a thriving aquatic plant community. However, eutrophication often causes turbid water, high algal productivity, and low species diversity and abundance of submerged macrophytes. A key indicator of the ecological state of lake ecosystems is the maximum growing depth (MGD) of aquatic plants. However, few studies have yet quantified the relationship between changes in external phosphorus (P) input to a lake and associated variation in MGD. This study examines the relationship between these variables in Loch Leven, a shallow, eutrophic loch in Scotland, UK. A baseline MGD value from 1905 and a series of more recent MGD values collected between 1972 and 2006 are compared with estimated P loads over a period of eutrophication and recovery. The results suggest a close relationship between changes in MGD of macrophytes and changes in the external P load to the loch. Variation in MGD reflected the ‘light history’ that submerged macrophytes had been exposed to over the 5-year period prior to sampling, rather than responding to short term, within year, variations in water clarity. This suggests that changes in macrophyte MGD may be a good indicator of overall, long term, changes in water quality that occur during the eutrophication and restoration of shallow lakes.     

典型高原湖滨带底泥细菌群落结构及多样性特征

【背景】高原湖泊的富营养化日趋严重,而湖滨带作为湖泊的保护屏障对外源污染物具有拦截净化等作用,水环境变化则会对底泥细菌产生深刻影响。【目的】探究高原湖滨带底泥细菌群落结构特征及与水体富营养化之间的联系。【方法】基于16S rRNA基因高通量测序技术分析了阳宗海南岸湖滨带8个不同样点的底泥细菌群落结构及多样性,并结合样品水体环境因子,采用主成分分析(PCA)和冗余分析(redundancy analysis,RDA)探讨了水体富营养化对底泥细菌群落结构及丰富度的影响。【结果】湖滨带底泥细菌与水体富营养化程度存在响应关系,在水体富营养化程度高的区域(S3)细菌丰富度较高,操作分类单元(operationaltaxonomicunits,OTU)高达1473。反之,在富营养化程度低的区域(S1)细菌丰富度较低,OTU为730。阳宗海南岸湖滨带底泥中主要优势菌门为变形菌门(Proteobacteria)和绿弯菌门(Chloroflexi),含有少量的放线菌门(Actinobacteria)、酸杆菌门(Acidobacteria)和厚壁菌门(Firmicutes);绿弯菌门(Chloroflexi)与水体富营养化程度具有相关性,在中度富营养化区域,绿弯菌门(Chloroflexi)的比重高达44.1%,而在轻度富营养化区域绿弯菌门(Chloroflexi)的比重仅为15.6%。通过环境因子分析发现,阳宗海湖滨底泥细菌受总磷(TP)、叶绿素a (Chla)和总氮(TN)影响较强。【结论】研究结果明确了高原湖泊湖滨带底泥细菌种群的结构、变化特征及其对于水体富营养化的响应,加深了高原湖泊底泥细菌的了解,为高原湖泊水体富营养化的防治提供理论基础。     

Eutrophication and the macroscope

It is important to view eutrophication as an increase in the supply of organic matter to an ecosystem rather than as a simple problem of nutrient pollution. This emphasizes that eutrophication is a fundamental change in the energetic base that may propagate through the system in various ways and produce a variety of changes. Some of these changes may be desirable (e.g., increased secondary production) and some may not (e.g., hypoxia). Defining eutrophication in terms of changing nutrient concentrations or chlorophyll levels or species composition confuses symptoms with the underlying phenomenon. While nutrient enrichment is the most common cause of eutrophication, it is not the only one. As recent and ongoing nutrient reductions make an impact in the coastal waters of the wealthier nations, we will see an increasing number of systems in which primary production is decreasing. This reduction in the supply of organic matter is here defined as oligotrophication, a phenomenon now well documented in lakes. So far, there has been little appreciation of this limnological study by coastal marine ecologists or managers, but there is much we can learn from it. The great ecologist H.T. Odum long argued that we need ‘macroscopes’ to help ecologists see the problems they study as they are embedded in the larger scales of nature and society. Marine eutrophication (and oligotrophication) is a perfect example of a problem that must be studied with a view toward the larger scales as well as toward the microscopic details. While much of the hardware (e.g., satellite imagery) for the mythical macroscope has been developed in the last 30 years, many ecologists and managers still look at eutrophication as a local problem linked to local sources of nutrient enrichment. Such a parochial view isolates eutrophication from its long intellectual history—a history that is linked to the development of our understanding of production in coastal waters. It also neglects the intellectual richness and complexity of eutrophication. One example of the importance of the macroscopic view is the emerging importance of climate-induced changes in phenology and the consequences of changing phenology on productivity. These changes may lead to eutrophication or oligotrophication. Climate changes may also exacerbate or alleviate conditions such as hypoxia that are associated with eutrophication. Seeing eutrophication in the macroscopic view is important for understanding and managing the phenomenon. Guest editors: J. H. Andersen & D. J. Conley Eutrophication in Coastal Ecosystems: Selected papers from the Second International Symposium on Research and Management of Eutrophication in Coastal Ecosystems, 20–23 June 2006, Nyborg, Denmark     

Impact of prehistoric settlements on the Cladocera in the sediments of Lakes Suszek,Bł\cedowo,and Skrzetuszewskie

An analysis of Cladocera has been made on sediments from the three Polish lakes Suszek, B\cedowo, and Skrzetuszewskie. The analysed sediments are gyttja from the Subboreal and Subatlantic periods, during which the lakes were subject variously to eutrophication. The eutrophication process has been analysed from the frequency of Cladocera, particularly the index species, and has been correlated with climatic and settlement changes. It was found that in Suszek lake, in which no significant human activity had taken place (palynologically documented), the eutrophication must have been slow and gradual. On the contrary, in the two remaining lakes, in which the human influence was more intense, the eutrophication process underwent intensive changes and coincided somewhat with settlement fluctuations.     

Ecological sensitivity of marl lakes to nutrient enrichment: evidence from Hawes Water,UK

相似文献   

Biological diversity of the Yala Swamp lakes, with special emphasis on fish species composition, in relation to changes in the Lake Victoria Basin (Kenya): threats and conservation measures

During the second half of the last century, the Lake Victoria ecosystem has undergone drastic ecological changes. Most notable has been the decline in the populations of many endemic cichlid fishes. The lake has lost nearly 200 haplochromines and one tilapiine, Oreochromis esculentus. The above changes have been attributed to effects of species stocking and, in particular, from predation pressure by the introduced Nile perch, Lates niloticus. Other factors that have led to the decline of the endemic species include intensive non-selective fishing, extreme changes in the drainage basin, increased eutrophication, and the invasion of the lake by the water hyacinth, Eichhornia crassipes. However, the remnants of some species that had disappeared from Lake Victoria occur abundantly in the Yala Swamp lakes (Kanyaboli, Sare and Namboyo). This paper discusses the biodiversity of the swamp and the three lakes and gives suggestions for their conservation.     

Ecosystem-level effects of re-oligotrophication and N:P imbalances in rivers and estuaries on a global scale

Trends and ecological consequences of phosphorus (P) decline and increasing nitrogen (N) to phosphorus (N:P) ratios in rivers and estuaries are reviewed and discussed. Results suggest that re-oligotrophication is a dominant trend in rivers and estuaries of high-income countries in the last two–three decades, while in low-income countries widespread eutrophication occurs. The decline in P is well documented in hundreds of rivers of United States and the European Union, but the biotic response of rivers and estuaries besides phytoplankton decline such as trends in phytoplankton composition, changes in primary production, ecosystem shifts, cascading effects, changes in ecosystem metabolism, etc., have not been sufficiently monitored and investigated, neither the effects of N:P imbalance. N:P imbalance has significant ecological effects that need to be further investigated. There is a growing number of cases in which phytoplankton biomass have been shown to decrease due to re-oligotrophication, but the potential regime shift from phytoplankton to macrophyte dominance described in shallow lakes has been documented only in a few rivers and estuaries yet. The main reasons why regime shifts are rarely described in rivers and estuaries are, from one hand the scarcity of data on macrophyte cover trends, and from the other hand physical factors such as peak flows or high turbidity that could prevent a general spread of submerged macrophytes as observed in shallow lakes. Moreover, re-oligotrophication effects on rivers may be different compared to lakes (e.g., lower dominance of macrophytes) or estuaries (e.g., limitation of primary production by N instead of P) or may be dependent on river/estuary type. We conclude that river and estuary re-oligotrophication effects are complex, diverse and still little known, and in some cases are equivalent to those described in shallow lakes, but the regime shift is more likely to occur in mid to high-order rivers and shallow estuaries.     

Why do reed beds decline and fail to re‐establish? A case study of Dutch peat lakes

相似文献   

Aggregated indices for trends in eutrophication of different types of fresh water in the Netherlands

As in many European countries, eutrophication of surface waters is a key problem in the Netherlands, caused by high concentrations of nitrogen (N) and phosphorus (P). For implementation of the EU Water Framework Directive (WFD) in the Netherlands, surface water types have been identified and for each water type environmental quality standard concentrations (EQS) were determined for both nutrients. With these standards, a new method was developed to quantify trends in water quality with respect to eutrophication on a national scale for the period 1990–2010. Firstly, monitoring data were aggregated to seven classes of surface water. Next, for each water class and each nutrient, a Nutrient Index was developed to express the degree of exceedance of EQS (distance-to-target method). The Nutrient Index for N shows a minor exceedance of EQS as well as an improvement in all water types; for P, the index shows a major exceedance in small stagnant waters throughout the 1990–2010 period, whereas in major rivers and lakes levels were close to EQS. Thirdly, the indices for seven surface water classes were aggregated to one index for each nutrient, and finally to a national Eutrophication Index combining N and P. This Eutrophication Index integrates all monitoring data and shows an improvement in the period 1990–2003 and stabilization since 2004.     

The state of the environment of the Loosdrecht lakes

The Loosdrecht lakes are a system of shallow, interconnected, peat lakes in the centre of The Netherlands. The main environmental functions of the Loosdrecht lakes are nature and recreation. From the point of view of the Dutch policy, a Specific Environmental Quality (Bijzondere Milieukwaliteit) should be set for these lakes.The most serious environmental problem of the area is eutrophication. The Loosdrecht lakes have, by increasing external phosphorus loading, changed, from clear lakes with few macrophytes, followed by a period of abundant characean growth, to turbid lakes dominated by cyanobacteria and detrital matter. Eutrophication was counteracted by use of sewerage systems and dephosporization of the supply water. The resultant decrease in external phosphorus loading did not result in a decrease of turbidity by suspended particles.The eutrophication of the lake ecosystems was described as a series of phases. One of those phases, the status around 1940, has been used as an ecological reference system.By means of a graphical presentation technique, the so-called AMOEBE-approach, the state of the environment of the Loosdrecht lakes has been visualized. Thirty-two ecological parameters, including both biotic and abiotic factors, have been selected and quantified. Concrete target values for these parameters have been derived from historical reports and from Lake Western Loenderveen, located close to the Loosdrecht lakes, but less eutrophic.The general conclusion is that the state of the environment of the Loosdrecht lakes is far from what is required with respect to a Specific Environmental Quality, as many of the selected parameters, like water transparency, total phosphorus, mineral nitrogen, cyanobacteria, bream, pike, macrophytes, birds and otter, deviate by over an order of magnitude from their desired levels.     

Human impacts on the African Great Lakes

The African Great Lakes are important sources of fishes and water for domestic use, are used as avenues of transport, and receive agricultural, domestic and industrial effluents and atmospheric residues. Some of these lakes have speciose fish faunas of great interest to science. The catchment areas of some of the lakes are highly populated and user conflicts have increased the demands on the lakes' resources. There have been drastic reductions in fish stocks in most of the lakes due to overfishing. Introductions of new fish species, though followed by increases in fish catches, have been accompanied by a decline and in some cases extinction of native fish species. Some of the lakes have been invaded by the water hyacinth, Eichhornia crassipes. Agricultural activities, deforestation and devegetation of the catchment areas have increased siltation, and led to loss of suitable habitats and biodiversity. There are increased nutrient inputs from agriculture, sewage and industrial discharges and combustion processes which can cause eutrophication. There are also increased threats of toxic pollution from industrial waste discharge, mining, pesticides, and oil residues and spills. Climatic changes may also affect thermal stability of the lakes. These factors threaten availability of dietary protein, clean water and biodiversity. National and international efforts are required to manage the fisheries, guide the introduction of exotics, conserve biodiversity, control the water hyacinth, control eutrophication, reduce input of contaminants and manage climate change.     

Palaeolimnological investigations in Poland based on Cladocera (Crustacea)

The results of subfossil Cladocera analysis obtained from deposits of 26 lakes throughout Poland have been presented. For years throughout Poland a broad range of palaeolimnological studies have been conducted. Their aim is to discover the historical development of water basins and climatic changes in the course of the last 13,000 years and also to investigate the gradual influence of man on the ecosystem with particular emphasis on the last few decades. The hitherto obtained results of palaeolimnological studies, including the results of Cladocera analysis, have yielded information about the development of lakes and provided the basis for plans of certain reservoirs and their basins. Over the past years, analysis of subfossil Cladocera has become one of the leading palaeolimnological methods. The results of detailed qualitative and quantitative analysis of Cladocera remains from sediments of 15 lakes allowed for a reconstruction of the lakes' development. The littoral and limnetic regions, changing trophy, from oligotrophy to advanced eutrophication, changes in pH and fluctuation of water levels, as well as changes resulting from settlement — from Mesolithic and Neolithic through Medieval times until the present — have been reconstructed. For individual lakes, phases of Cladocera development and periods of eutrophication were indicated which partially correlated with certain pollen zones as well as periods of human impact and geochemical effects.     

Can the EU agri-environmental aid program be extended into the coastal zone to combat eutrophication?

Eutrophication of coastal waters is a serious environmental problem with high costs for society globally. This is a development which demands immediate environmental action along many coastal sites. Since the 1980s, mussel farming has been recognized by Swedish environmental authorities as a possible measure to improve coastal water quality. Concepts and management strategies on how to increase mussel farming and thus combat coastal marine eutrophication has recently been developed in Sweden. The main principle of this development has been the implementation of nutrient trading as a management tool. This imposes demands on those who emit the pollution through the establishment of emission quotas, which are traded and bought by the emitter. The seller is a nutrient harvesting enterprise, e.g., a mussel farmer. This principle is particularly straightforward when the nutrients are discharged from a point source. When examining the nutrient supply from all diffuse sources, the situation is more complex. However, since the major part of the nutrient supply to coastal waters in many areas of Europe has its origin in agricultural operations, we suggest that the EU agro-environmental aid program could be extended into the coastal zone in order to combat eutrophication. In practice, this should involve support paid to mussel farming enterprises through their harvest of mussels (and thus their harvest of nutrients) in the same way as support is paid to agricultural farmers for operations that reduce nutrient leakage from their farmland. This is a simple, cost-effective and straightforward way of improving coastal water quality at many coastal sites that will, at the same time, provide coastal jobs. However, this eutrophication combat method depends on the EU agro-environmental aid program being extended beyond the shoreline. Guest editors: J. H. Andersen & D. J. Conley Eutrophication in Coastal Ecosystems: Selected papers from the Second International Symposium on Research and Management of Eutrophication in Coastal Ecosystems, 20–23 June 2006, Nyborg, Denmark     

Assessing the efficacy of chironomid and diatom assemblages in tracking eutrophication in High Arctic sewage ponds

Eutrophication is the most common water quality issue affecting freshwaters worldwide. Paleolimnological approaches have been used in temperate regions to track eutrophication over time, placing changes in historical context. Diatoms (Bacillariophyta) have a direct physiological response to changes in nutrients and are effective indicators of lake trophic status. Chironomids (Diptera) have also been used to track nutrient conditions; however, given that nutrients and oxygen are often tightly linked, it is difficult to disentangle which variable is driving shifts in assemblages. Here, we analyze chironomid and diatom remains in sediments from sewage-impacted ponds in the High Arctic. These ponds have the unusual characteristics of elevated nutrient and oxygen concentrations, unlike those of typical eutrophic lakes where deepwater oxygen is often depleted. Our data show that while diatom assemblages responded to changing nutrients, no concomitant changes in chironomid assemblage composition were recorded. Furthermore, the dominance of oligotrophic, cold stenothermic chironomid taxa, and lack of so-called “eutrophic” species in the eutrophic sewage ponds suggests that oxygen, not nutrients, structures chironomid assemblages at these sites.     

Eutrophication: An ecological vision

The present review deals with the studies conducted on the impact of phosphorus on growth of aquatic plants causing eutrophication in well-known water bodies the world over. The review covers the definition and concept of eutrophication and the adverse effects on quality and ecosystem functioning. The eutrophication of several water bodies leads to significant changes in the structure and function of the aquatic ecosystem. Several activities of human interest, including navigation and power generation, are hampered. A large number of lakes in the United States, Europe, and Asia have recently been found to be highly eutrophic. Water, the precious fluid, is not uniformly distributed throughout the surface of the earth. Most of the water bodies world over are surrounded with densely populated human settlement areas and agricultural fields. The size of smaller water bodies in human settlement areas is on the decrease with rise in population. After treatment, a large quantity of sewage from the households is regularly discharged into the water bodies. The runoff brings down fertilizers and other chemicals from agricultural fields. The phosphorus contained in these effluents is known to promote excessive growth of plants. This review is an account of the role, sources, and monitoring of phosphorus, as well as its cycle. The natural phosphorus cycle originating from the weathering of phosphate rock is now a two-way operation, due to significant addition of phosphorus from anthropogenic sources. The detergents that are the major source of phosphorus inputs into water bodies (through sewage and drainage systems) have been thoroughly discussed. The major part of detergents comprises builders containing polyphosphate salts. An environment-friendly and effective synthetic builder is yet to be developed to replace existing phosphorus containing builders of detergents. The utility of the alternative builders available has been reviewed. Nitrogen has also been reported to affect the phytoplankton production in eutrophic waters in temperate regions. Several environmental factors have also been found to add to the problem of eutrophication in addition to nutrients. Several limiting factors—namely, CO₂ level, temperature, pH, light, and dissolved oxygen—are known to affect eutrophic water bodies. Eutrophication not only results in algal bloom but also affects wetland plants and activates early onset of natural succession at a relatively faster rate. Some of the plant species reported and studied world over are the best indicators of the level of eutrophication. The studies on the change in structure, function, and diversity of the ecosystem have been used as parameters to assess the level of eutrophication. In several countries adequate control measures have been adopted in to control eutrophication. But these measures were found to be only partially effective in controlling the phosphorus unloading in water bodies. In this review some control measures are suggested, with emphasis on biological control. The review concludes by taking into account the ecological prospective of the water—the precious fluid and a basis of life on the earth.     

Assessing eutrophication in the Portuguese continental Exclusive Economic Zone within the European Marine Strategy Framework Directive

This study reports the state and causes of eutrophication in the Portuguese continental Exclusive Economic Zone (EEZ), during a 14-year period (1995–2008), following the European Marine Strategy Framework Directive (MSFD) and using the trophic index TRIX for an integrated evaluation of indicators of eutrophication, and identifies areas where monitoring is needed to improve the eutrophication assessment. A non-continuous dataset for the 8 indicators specified by the MSFD for eutrophication assessment was used, including published and grey data. Eutrophication indicators were validated and thresholds reviewed, considering regional differences. The diatom:flagellate ratio was found a poor indicator of eutrophication as shifts in the diatom:flagellate ratio naturally occur associated with alternating water column turbulence and upwelling, and stratification, and therefore, could not be associated with anthropogenic nutrient enrichment effects. Assessment areas were, as a whole, classified as non-problem areas concerning eutrophication. Although nutrient enrichment was observed in coastal waters, related to river plume influence, nutrient enrichment direct and indirect effects were generally not detectable, possibly due to water column dispersion and mixing processes. Only occasionally, mild eutrophication was found in specific areas under the influence of major river (Douro, Vouga and Guadiana) plumes, associated with high nutrient and phytoplankton biomass levels and seagrass decline, which indicates the need for directed monitoring on eutrophication in those areas.     

减少农业对水体污染的对策与措施

水体富营养化是一个全球关注的问题。逐渐增加的化肥施用量和畜禽养殖业产生的粪便进一步引起营养流失,进而产生了N、P营养物质的不平衡。因此农业面源污染已被视为水体富营养化的主要污染源。本文简要地概述了农业面源污染对造成水体富营养化的危害,同时介绍了国内外防治农业面源污染的主要措施,包括面源控制措施和转移转化措施。指出了建立稳定、和谐与良性循环的农业生态系统是治理农业面源污染的长久之计。     

Historical changes in species composition and richness accompanying perturbation and eutrophication of Danish lowland streams over 100 years

1. European lowland streams have experienced increased perturbation and eutrophication during the past 100 years. We use archive information from 27 Danish stream sites around 1896 and new data from 208 stream sites in 1996 to evaluate the accompanying changes in stream vegetation. Among the stream sites, 13 were both studied in 1896 and 1996. 2. The species richness of submerged plants has declined profoundly over the 100-year period, particularly among the large group of Potamogeton species. This is evident both from the direct comparison of the 13 stream reaches included in both studies, and from the general comparison of all stream reaches included in the two studies. 3. The Potamogeton vegetation has become less diverse, and is now dominated by species resistant to frequent disturbance through a high dispersal capacity. Potamogeton species, adapted to eutrophic conditions, have also increased relative to species more typical of oligotrophic conditions over this period. The dominant submerged species in the contemporary stream vegetation generally show a high capacity for dispersal and regrowth of detached shoots. 4. The decline of species richness in Danish streams can be partly explained by a decline in the species richness in lakes in the stream system. The rich vegetation observed downstream of lakes in the past has mostly disappeared due to loss of the vegetation in the now eutrophic lakes and increasing turbidity downstream. 5. The overall decline in richness, and the directional change in dominance patterns among stream species, can thus be explained by the loss of suitable habitats and the strong anthropogenic impacts, which have driven several European aquatic species close to extinction.