Phytoplankton communities and biomass size structure (fractionated chlorophyll “a”), along trophic gradients of the Basque coast (northern Spain)

Eutrophication is a major threat to coastal ecosystems. Within Europe, the Water Framework Directive (WFD) has established the need of developing methods of assessment. Bulk chlorophyll “a” is used world-wide as an indicator of eutrophication. However, the size structure of the phytoplankton communities has not been investigated, in detail, in relation to eutrophication pressures. This study investigates the suitability of fractionated chlorophyll “a” (<10 and >10 μm), as an indicator of eutrophication. Along the Basque coast (northern Spain) several water bodies, ranging from offshore waters to the heads of the estuaries, were surveyed during 2008. Physico-chemical conditions and chlorophyll “a” showed a distinct spatial gradient. Trophic richness increased towards the middle and inner parts of the estuaries, where nutrient inputs, from natural or anthropogenic sources, together with the residence time of the water are usually higher. In summer, phytoplankton biomass and abundance decreased, generally, in offshore and coastal waters; in estuaries, they tended to increase. The chlorophyll distribution within the two size fractions was coherent with the phytoplankton taxonomic composition. In summer, the relative abundance of small-sized cells (diatoms and non-siliceous taxa) increased. The relationships between size-fractionated chlorophyll and physico-chemical variables differed, when comparing the offshore and coastal waters, with the estuaries. In the offshore and coastal waters, a strong seasonality was observed; in estuaries, an important spatial component was found. Fractionated chlorophyll provided complementary useful information on anthropogenic pressures. However, more research is necessary to utilise this variable as a tool for ecological status assessment, within the WFD.     

Classifying aquatic macrophytes as indicators of eutrophication in European lakes

Aquatic macrophytes are one of the biological quality elements in the Water Framework Directive (WFD) for which status assessments must be defined. We tested two methods to classify macrophyte species and their response to eutrophication pressure: one based on percentiles of occurrence along a phosphorous gradient and another based on trophic ranking of species using Canonical Correspondence Analyses in the ranking procedure. The methods were tested at Europe-wide, regional and national scale as well as by alkalinity category, using 1,147 lakes from 12 European states. The grouping of species as sensitive, tolerant or indifferent to eutrophication was evaluated for some taxa, such as the sensitive Chara spp. and the large isoetids, by analysing the (non-linear) response curve along a phosphorous gradient. These thresholds revealed in these response curves can be used to set boundaries among different ecological status classes. In total 48 taxa out of 114 taxa were classified identically regardless of dataset or classification method. These taxa can be considered the most consistent and reliable indicators of sensitivity or tolerance to eutrophication at European scale. Although the general response of well known indicator species seems to hold, there are many species that were evaluated differently according to the database selection and classification methods. This hampers a Europe-wide comparison of classified species lists as used for the status assessment within the WFD implementation process.     

Ecological threshold responses in European lakes and their applicability for the Water Framework Directive (WFD) implementation: synthesis of lakes results from the REBECCA project

The objective of this synthesis is to present the key messages and draw the main conclusions from the work on lakes in the REBECCA project, pointing out their links to theoretical ecology and their applicability for the WFD implementation. Type-specific results were obtained from analyses of large pan-European datasets for phytoplankton, macrophytes, macroinvertebrates and fish, and indicators and relationships showing the impact of eutrophication or acidification on these biological elements were constructed. The thresholds identified in many of the response curves are well suited for setting ecological status class boundaries and can be applied in the intercalibration of classification systems. Good indicators for phytoplankton (chrysophytes, cyanobacteria) and macrophytes (isoetids and charaphytes) responses to eutrophication were identified, and the level of eutrophication pressure needed to reach the thresholds for these indicators was quantified. Several existing metrics developed for macrophytes had low comparability and need further harmonisation to be useful for intercalibration of classification systems. For macroinvertebrates, a number of metrics developed for rivers turned out to be less useful to describe lake responses to eutrophication and acidification, whereas other species based indicators were more promising. All the biological elements showed different responses in different lake types according to alkalinity and humic substances, and also partly according to depth. Better harmonisation of monitoring methods is needed to achieve better precision in the dose–response curves. Future research should include impacts of hydromorphological pressures and climate change, as well as predictions of timelags involved in responses to reduction of pressures.     

Developing a systematic simulation-based approach for selecting indicators in strategic cumulative effects assessments with multiple environmental valued components

Indicator selection is a critical step in conducting effective strategic cumulative effects assessments. Selecting an appropriate set of indicators to represent multiple and sometimes disparate values is particularly challenging because the interpretation of impacts depends on indicator roles and relationships among indicators. However, systematic approaches for selection of indicators for strategic cumulative effects assessments (CEA) are unclear. For a 909,000 ha case study area involving 214 watersheds in coastal British Columbia, we defined a suite of twenty indicators linked to six Valued Components (VCs) that could be forecasted for forest, riparian and species at risk as three key values consistent with present land-use planning policies in British Columbia, Canada. We used spatio-temporal process-based models to project and integrate the stressor–response relationships between forest harvesting and run-of-river power resource management activities and the suite of selected indicators. For a likely development scenario, we assessed the correlative structure among projected indicator responses and, using a PCA-based analysis of outcomes, identified both patterns of potential redundancies and ecological processes linking indicators and dominant processes influencing VCs. Our results suggest that strategic CEAs will benefit if indicator selections are not made independently for each VC. Identifying the type of indicator, i.e., pressure or condition, and scale of its representation was important in determining if assessed impacts for individual indicators could be appropriately integrated to quantify overall impacts in the landscape. Consideration of indicator–indicator relationships both within and among VCs clarifies the influences of spatial scale, potential redundancies among indicators, and the role of underlying ecological processes in interpreting and aggregating indicator responses. Our case study demonstrates that relative scales of ecological processes, disturbances and management actions can limit how cohesive the interpretations of impacts may be across VCs in strategic CEA. Analysis of correlative structures among the twenty indicators suggested criteria-based statistical redundancies occurred between only two indicator pairs, however PCA suggested three ecological processes (road disturbance, Spotted Owl habitat state, retention and recruitment of old forest) were operating to relate behaviors of multiple indicators. Careful consideration of the interacting roles of ecological processes as they relate to values is required when determining appropriate indicators and designing how best to aggregate indicator results into an effective strategic CEA. A three step systematic and generalizable approach to forecasting present and future states of indicators will improve efficiencies and effectiveness of strategic CEA.     

Light dependence of Zostera marina annual growth dynamics in estuaries subject to different degrees of eutrophication

We examined the coupling between eelgrass growth dynamics and surface irradiance over an annual cycle in four shallow estuaries of the Waquoit Bay system (MA, USA) that have similar physical characteristics, but are subject to different land-derived nitrogen loading rates and eutrophication. Contrary to our hypothesis, the results show that most measures of eelgrass demographics were positively correlated with surface irradiance in all four estuaries. Of the 45 regression models adjusted between irradiance and demographic variables (density, plastochrone intervals, and above- or belowground biomass, growth, and production, on both a per shoot and areal basis), only nine were non-significant, and only six of those corresponded to the eutrophic estuaries. There was a lack of correlation between shoot density and irradiance in the eutrophic estuaries, in contrast to the strong coupling in estuaries with the lowest nitrogen loads. Severe light limitation and other deleterious impacts imposed by macroalgal canopies on newly recruiting shoots in the eutrophic estuaries likely contributed to the lack of correlation between shoot density and irradiance at the water's surface. Because the range in eutrophication included the range of conditions at which eelgrass can survive, the relatively consistent temporal coupling between surface irradiance and most eelgrass demographic variables found here may also be a feature of other shallow temperate systems undergoing eutrophication, and indicates a measure of plant recruitment (density) to be one of the first parameters to become uncoupled from light reaching the water's surface.     

基于指标自动筛选的新疆开孔河流域生态健康评价

生态健康评价对了解区域生态健康状况和促进区域可持续发展具有重要意义,如何自动筛选出能反映生态系统特性的重要指标,是生态健康定量评估的关键问题。基于压力-状态-响应(PSR,Press-State-Response)框架和生态等级网络框架(EHN,Ecological Hierarchy Network),通过文献调研和因果分析建立要素层与指标层之间的交叉联系,构建了生态健康评价"网状"指标体系;在保证指标体系完备性基础上,通过结合主成分分析和熵权法的候选指标权重的客观计算,基于目标优化理论构建了评价指标的自动筛选模型,并基于中选指标计算了新疆开孔河流域2001—2017年生态健康指数(EHCI,Ecological Health Comprehensive Indexes),分析其空间分异和时间变化特征。结果表明:利用所建立的评价指标自动筛选模型,开孔河流域生态健康评价指标由31个候选指标自动筛选出了17个中选指标,用54.8%的指标表达了85.98%的信息,中选的17个指标在干旱/半干旱区域有关文献中应用较多,使用频次比例都在20%以上,其中归一化植被指数(NDVI,Normaliz...     

Strength and uncertainty of phytoplankton metrics for assessing eutrophication impacts in lakes

Phytoplankton constitutes a diverse array of short-lived organisms which derive their nutrients from the water column of lakes. These features make this community the most direct and earliest indicator of the impacts of changing nutrient conditions on lake ecosystems. It also makes them particularly suitable for measuring the success of restoration measures following reductions in nutrient loads. This paper integrates a large volume of work on a number of measures, or metrics, developed for using phytoplankton to assess the ecological status of European lakes, as required for the Water Framework Directive. It assesses the indicator strength of these metrics, specifically in relation to representing the impacts of eutrophication. It also examines how these measures vary naturally at different locations within a lake, as well as between lakes, and how much variability is associated with different replicate samples, different months within a year and between years. On the basis of this analysis, three of the strongest metrics (chlorophyll-a, phytoplankton trophic index (PTI), and cyanobacterial biovolume) are recommended for use as robust measures for assessing the ecological quality of lakes in relation to nutrient-enrichment pressures and a minimum recommended sampling frequency is provided for these three metrics.     

基于组合可拓综合分析法的鄱阳湖流域水质富营养化评价

长期跟踪定位评价湖泊的水质营养化程度,对于实现地区水功能具有重要意义。针对评价方法中指标选取的可行性、单一性、权重赋值的主观随意性以及水质变化的模糊性、随机性、动态性和生物指示性等特点,采用了可拓综合评价法和浮游生物调查与室内测定法相结合,构建了组合可拓综合分析法,一方面利用可拓综合分析法对鄱阳湖流域5个代表性观测站点的10年的年均（每2年）观测数据进行评价;另一方面通过浮游生物指示法对该5个站点的水质进行富营养化评价,以生物指示评价法所得等级与可拓综合分析法评定等级吻合的最多次数所对应等级作为组合可拓综合评价法的评价等级。结果表明：（1）自2006年以来鄱阳湖流域水体富营养化水平较为平稳,总体呈好转势态。2010年有4个观测点的水体达到富营养化程度,而在2014年湖区的蛤蟆石和鄱阳水质略有所改善,达到轻富营养化程度,都昌、康山、星子站点的水体为中营养化,改善幅度较大,水质较好;（2）从湖区的地理区位看,鄱阳湖湖区的南部和西部的水质富营养化程度总体上要好于北部、东部和中部湖区,水质富营养化程度表现为区域的不均匀性。     

A proposal of framework to obtain an integrated biodiversity indicator for agricultural ponds incorporating the simultaneous effects of multiple pressures

One of the promising approaches to monitoring biodiversity is assessing the status of pressures driving the biodiversity state. To achieve this, we need to identify the principal pressures that cause simultaneous biodiversity loss across taxonomic groups and clarify how multiple pressures act synergistically or at least simultaneously to decrease biodiversity in the focal ecosystem. Here, we used a series of 64 ponds as a case study and we developed a framework for an integrated biodiversity indicator that took into consideration the estimated relative importance of multiple pressures. The indicator is defined as a function of the pressure(s) and is parameterized to explain a number of individual indicators of biodiversity, such as richness, abundance, and functional diversity of focal taxa. We selected aquatic macrophytes, Odonata, and benthic macroinvertebrates as the focal taxa. In addition, we focused on three types of pressure: eutrophication (represented by total phosphorus, total nitrogen, suspended solids, chlorophyll a, and density of cyanobacteria of pond water), habitat destruction (land-use type around the pond and pond bank protection), and invasive alien species (abundance of bluegill, largemouth bass, red swamp crayfish, and American bullfrog). We then evaluated the relationships among direct pressures and the individual biodiversity indicators and used a hierarchical Bayesian approach to calculate the integrated biodiversity indicator. Using this framework, we demonstrated that eutrophication had greater effects on the state of biodiversity of the agricultural ponds than did habitat destruction or the presence of invasive alien species. We also showed that the integrated indicator could well explain the behaviors of several individual biodiversity indicators, including total richness, endangered species richness, and functional diversity of focal taxa. These results demonstrate the advantages of the framework in providing a more practical method for assessing biodiversity, and quantifying the relative importance of the major threats to biodiversity to prioritize strategies in conservation planning and policy making.     

Methodological challenges in assessing the environmental status of a marine ecosystem: case study of the Baltic Sea

Assessments of the environmental status of marine ecosystems are increasingly needed to inform management decisions and regulate human pressures to meet the objectives of environmental policies. This paper addresses some generic methodological challenges and related uncertainties involved in marine ecosystem assessment, using the central Baltic Sea as a case study. The objectives of good environmental status of the Baltic Sea are largely focusing on biodiversity, eutrophication and hazardous substances. In this paper, we conduct comparative evaluations of the status of these three segments, by applying different methodological approaches. Our analyses indicate that the assessment results are sensitive to a selection of indicators for ecological quality objectives that are affected by a broad spectrum of human activities and natural processes (biodiversity), less so for objectives that are influenced by a relatively narrow array of drivers (eutrophications, hazardous substances). The choice of indicator aggregation rule appeared to be of essential importance for assessment results for all three segments, whereas the hierarchical structure of indicators had only a minor influence. Trend-based assessment was shown to be a useful supplement to reference-based evaluation, being independent of the problems related to defining reference values and indicator aggregation methodologies. Results of this study will help in setting priorities for future efforts to improve environmental assessments in the Baltic Sea and elsewhere, and to ensure the transparency of the assessment procedure.     

Comparative LCA of ethanol versus gasoline in Brazil using different LCIA methods

Purpose

The main objective of this study is to expand the discussion about how, and to what extent, the environmental performance is affected by the use of different life cycle impact assessment (LCIA) illustrated by the case study of the comparison between environmental impacts of gasoline and ethanol form sugarcane in Brazil.

Methods

The following LCIA methods have been considered in the evaluation: CML 2001, Impact 2002+, EDIP 2003, Eco-indicator 99, TRACI 2, ReCiPe, and Ecological Scarcity 2006. Energy allocation was used to split the environmental burdens between ethanol and surplus electricity generated at the sugarcane mill. The phases of feedstock and (bio)fuel production, distribution, and use are included in system boundaries.

Results and discussion

At the midpoint level, comparison of different LCIA methods showed that ethanol presents lower impacts than gasoline in important categories such as global warming, fossil depletion, and ozone layer depletion. However, ethanol presents higher impacts in acidification, eutrophication, photochemical oxidation, and agricultural land use categories. Regarding to single-score indicators, ethanol presented better performance than gasoline using ReCiPe Endpoint LCIA method. Using IMPACT 2002+, Eco-indicator 99, and Ecological Scarcity 2006, higher scores are verified for ethanol, mainly due to the impacts related to particulate emissions and land use impacts.

Conclusions

Although there is a relative agreement on the results regarding equivalent environmental impact categories using different LCIA methods at midpoint level, when single-score indicators are considered, use of different LCIA methods lead to different conclusions. Single-score results also limit the interpretability at endpoint level, as a consequence of small contributions of relevant environmental impact categories weighted in a single-score indicator.     

Biological assessment of European lakes: ecological rationale and human impacts

相似文献   

Ecosystem quality in LCIA: status quo,harmonization, and suggestions for the way forward

Purpose

Life cycle impact assessment (LCIA) results are used to assess potential environmental impacts of different products and services. As part of the UNEP-SETAC life cycle initiative flagship project that aims to harmonize indicators of potential environmental impacts, we provide a consensus viewpoint and recommendations for future developments in LCIA related to the ecosystem quality area of protection (AoP). Through our recommendations, we aim to encourage LCIA developments that improve the usefulness and global acceptability of LCIA results.

Methods

We analyze current ecosystem quality metrics and provide recommendations to the LCIA research community for achieving further developments towards comparable and more ecologically relevant metrics addressing ecosystem quality.

Results and discussion

We recommend that LCIA development for ecosystem quality should tend towards species-richness-related metrics, with efforts made towards improved inclusion of ecosystem complexity. Impact indicators—which result from a range of modeling approaches that differ, for example, according to spatial and temporal scale, taxonomic coverage, and whether the indicator produces a relative or absolute measure of loss—should be framed to facilitate their final expression in a single, aggregated metric. This would also improve comparability with other LCIA damage-level indicators. Furthermore, to allow for a broader inclusion of ecosystem quality perspectives, the development of an additional indicator related to ecosystem function is recommended. Having two complementary metrics would give a broader coverage of ecosystem attributes while remaining simple enough to enable an intuitive interpretation of the results.

Conclusions

We call for the LCIA research community to make progress towards enabling harmonization of damage-level indicators within the ecosystem quality AoP and, further, to improve the ecological relevance of impact indicators.

     

Influence of groundwater exploitation on the ecological status of streams in a Mediterranean system (Selva Basin,NE Spain)

The ecological status of streams depends on an equilibrium between hydrological processes and biological dynamics. Water discharge is the main requisite for a wealthy riparian habitat. Nevertheless, human practices severely affect water availability through stream water derivation and groundwater withdrawal. In this sense, impacts upon aquifer water storage and its effects on base flow generation have a significant effect on stream biology. Consequently, biological indicators will point out poor conditions resulting from such human impacts. In this paper, the effects of groundwater exploitation on stream discharge and surface water quality are evaluated and compared to biological indicators in a Mediterranean catchment.The stream–aquifer relationship is investigated by considering the hydrological context of each river reach, including human pressures, and the hydraulic head in the contiguous alluvial aquifer, where it exists. These data allow us to differentiate distinct types of reaches that are defined according to a “Stream–Aquifer relationship and chemical Pressure” (SAP) classification, which is used later on to standardize the different hydrochemical and biological features of the sampling points.Stream water and groundwater hydrochemistry are compared to depict the hydraulic behavior of the sampled watercourses during wet and dry periods. Specific elements are used as tracers of groundwater inputs, wastewater influence, or even stagnant conditions during the dry season. This dataset defines a framework to interpret the biological status of each reach based on the Iberian biological monitoring working party indicator (IBMWP). Affinities between hydrological and hydrochemical conditions with biological indicator values allow the causal effects of groundwater exploitation on stream ecology to be defined.The use of multivariate principal component analysis shows that the dataset variance is distributed according to the SAP classification, and that variable grouping is in agreement with the observed hydrological processes and their effects on biological indicator values.This work provides evidence of the importance of groundwater dynamics on biological indicators in a human-modified environment. When using the SAP classification, biological indicators acquire a broader meaning as they reveal the status of biological processes and the causal references. Such information is relevant for water management assessment within the context of the European Water Framework Directive, as it emphasizes the control of groundwater exploitation as a key parameter in the preservation of stream ecological status and the achievement of the objectives of the directive.     

Nutrient cycling and foodwebs in Dutch estuaries

In this review several aspects of the functioning of the Dutch estuaries (Ems-Dollard, Wadden Sea, Oosterschelde, Westerschelde, Grevelingen and Veerse Meer) have been compared. A number of large European rivers (especially Rhine) have a prevailing influence on the nutrient cycling of most Dutch estuaries. Owing to the increased loading of the estuaries with nitrogen and phosphorus compounds, effects of eutrophication on the biological communities could be demonstrated, mainly in the western Wadden Sea. The causality, however, of the relation between increased nutrient loading and increased biomass and production of primary producers in the turbid tidal Dutch ecosystems is questioned. The most obvious biological effects of eutrophication have been observed in a non-tidal brackish lagoon, Veerse Meer. The estuarine food web received major attention. Budget studies of the main primary producers revealed a dominance of phytoplankton in all Dutch estuaries, followed by microphytobenthos in the tidal systems and macrophytes in the lagoons. The quantitative distribution of primary producers and primary and secondary consumers shows remarkable similarities along the physical and chemical estuarine gradients, notwithstanding the large variability in space and the considerable inconstancy over time. Among the secondary consumers (waterfowl, marine fish, larger invertebrates) the levels of organic carbon consumption — expressed in g C m⁻² y⁻¹ — are almost the same, when tidal estuaries are compared with non-tidal lagoons, notwithstanding the fact that the consumer populations show large qualitative differences. The transfer from primary consumers to secondary consumers reveals a bottle neck: especially during late winter, when macrozoobenthos reaches its lowest biomass, food may be a serious limiting resource for large numbers of migratory waders foraging on the intertidal flats. The consequences of the Deltaplan, the closure of several estuaries in the southwest of the Netherlands and their subsequent transfer into non-tidal lagoons, offer complicated case studies of ecosystem changes. Several examples of long-term trends in ecosystem development in Grevelingen lagoon have been discussed.     

Ecological status assessment of European lakes: a comparison of metrics for phytoplankton, macrophytes, benthic invertebrates and fish

Data on phytoplankton, macrophytes, benthic invertebrates and fish from more than 2000 lakes in 22 European countries were used to develop and test metrics for assessing the ecological status of European lakes as required by the Water Framework Directive. The strongest and most sensitive of the 11 metrics responding to eutrophication pressure were phytoplankton chlorophyll a, a taxonomic composition trophic index and a functional traits index, the macrophyte intercalibration taxonomic composition metric and a Nordic lake fish index. Intermediate response was found for a cyanobacterial bloom intensity index (Cyano), the Ellenberg macrophyte index and a multimetric index for benthic invertebrates. The latter also responded to hydromorphological pressure. The metrics provide information on primary and secondary impacts of eutrophication in the pelagic and the littoral zone of lakes. Several of these metrics were used as common metrics in the intercalibration of national assessment systems or have been incorporated directly into the national systems. New biological metrics have been developed to assess hydromorphological pressures, based on aquatic macrophyte responses to water level fluctuations, and on macroinvertebrate responses to morphological modifications of lake shorelines. These metrics thus enable the quantification of biological impacts of hydromorphological pressures in lakes.     

Effects of residual hydrocarbons on the reed community after 10 years of oil extraction and the effectiveness of different biological indicators for the long-term risk assessments

The selection of certain indicators is critical to undertake ecological risk assessments of long-term oil pollution and other environmental changes. The indicators should be easily and routinely monitored, be sensitive to pollution, respond to pollution in a predictable manner, and match the spatial and temporal scales of investigations. To compare the effectiveness of indicators for the long-term risk assessments, this study investigated the multiple ecological effects of chronic oil pollution on the plant community dominated by reed (Phragmites australis). The physiology, growth and reproduction of reed, together with the composition and productivity of the reed community, were measured around oil wells that have operated for approximately 10 years in the Yellow River Delta, eastern China. The predictive power of each indicator was evaluated using the coefficients of determination (R²) of linear regression models established for each indicator and soil Total Petroleum Hydrocarbons (TPH) concentration. The sensitivities of indicators were evaluated by comparing slopes of new established regression lines using standardized data. The top three indicators in terms of predictive power were leaf length, width and number, followed by the Shannon–Wiener index, Pielou evenness index and Simpson's diversity index. Community aboveground biomass, foliar projective coverage and species richness showed predictive power lower than those of the three diversity indexes, but higher than those of leaf net photosynthetic rate, reed height, aboveground biomass and vertical projective coverage of reed plants. Leaf transpiration, chlorophyll concentration and reed stem density showed no significant linear response to elevated soil TPH concentration. In terms of sensitivity, the top three biological indicators were Pielou evenness index, Simpson's diversity index and Shannon–Wiener index, followed by community vertical projective coverage, community aboveground biomass, and species richness. Leaf number, length and width were moderately sensitive, followed by reed coverage, aboveground biomass and height. The sensitivity of net photosynthetic rate was the lowest. The predictive power and sensitivities of indicators were compared in terms of their spatial and temporal scales. In conclusion, scale can be used to facilitate the selection of indicators, and the combination of different indicators may yield improved understanding of the various effects of elevated soil TPH concentration at the different biological levels.     

Proposed Local Ecological Impact Categories and Indicators for Life Cycle Assessment of Aquaculture

In this study we discuss impact categories and indicators to incorporate local ecological impacts into life cycle assessment (LCA) for aquaculture. We focus on the production stages of salmon farming—freshwater hatcheries used to produce smolts and marine grow‐out sites using open netpens. Specifically, we propose two impact categories: impacts of nutrient release and impacts on biodiversity. Proposed indicators for impacts of nutrient release are (1) the area altered by farm waste, (2) changes in nutrient concentration in the water column, (3) the percent of carrying capacity reached, (4) the percent of total anthropogenic nutrient release, and (5) release of wastes into freshwater. Proposed indicators for impacts on biodiversity are (1) the number of escaped salmon, (2) the number of reported disease outbreaks, (3) parasite abundance on farms, and (4) the percent reduction in wild salmon survival. For each proposed indicator, an example of how the indicator could be estimated is given and the strengths and weaknesses of that indicator are discussed. We propose that including local environmental impacts as well as global‐scale ones in LCA allows us to better identify potential trade‐offs, where actions that are beneficial at one scale are harmful at another, and synchronicities, where actions have desirable or undesirable effects at both spatial scales. We also discuss the potential applicability of meta‐analytic statistical techniques to LCA.     

河口生态系统氨氧化菌生态学研究进展

由amoA基因编码的氨单加氧酶(AMO)所调控的氨氧化作用,是硝化作用的限速步骤和中心环节,而含有amoA基因的氨氧化细菌(AOB)和氨氧化古菌(AOA)多样性与环境因子关系密切,对缓解河口生态系统因人类活动造成的富营养化等环境问题具有特别重要的意义。水、陆和海交汇形成高度变异的具环境因子梯度的河口生态系统,是研究AOA和AOB生态学的天然实验室。河口AOA与AOB的群落组成、丰富度特征和生物有效性,与河口主要环境因子盐度、富营养化程度、植被、温度、碳、氮、硫、铁等,尤其是对盐度和富营养化有着较为强烈的响应。AOA和AOB多样性变化规律及其与河口特有的环境因子之间的相关性,应当是今后我国河口氨氧化菌研究的方向和重点。包括:(1)建立有效的氨氧化菌活性评价方法;(2)研究AOA的同化作用方式;(3)依据氨氧化菌分类和组成对河口环境变化的适应进化机制,建议可作为指示河口环境质量变化的生物标记;(4)将传统的分离培养方法与现代分子生物学研究方法相结合,筛选我国河口高效的氨氧化菌,并将其应用于生产。     

The relative importance of light and nutrient limitation of phytoplankton growth: a simple index of coastal ecosystem sensitivity to nutrient enrichment

Anthropogenic nutrient enrichment of the coastal zone is now a well-established fact. However, there is still uncertainty about the mechanisms through which nutrient enrichment can disrupt biological communities and ecosystem processes in the coastal zone. For example, while some estuaries exhibit classic symptoms of acute eutrophication, including enhanced production of algal biomass, other nutrient-rich estuaries maintain low algal biomass and primary production. This implies that large differences exist among coastal ecosystems in the rates and patterns of nutrient assimilation and cycling. Part of this variability comes from differences among ecosystems in the other resource that can limit algal growth and production – the light energy required for photosynthesis. Complete understanding of the eutrophication process requires consideration of the interacting effects of light and nutrients, including the role of light availability as a regulator of the expression of eutrophication. A simple index of the relative strength of light and nutrient limitation of algal growth can be derived from models that describe growth rate as a function of these resources. This index can then be used as one diagnostic to classify the sensitivity of coastal ecosystems to the harmful effects of eutrophication. Here I illustrate the application of this diagnostic with light and nutrient measurements made in three California estuaries and two Dutch estuaries.