Ecological assessments with algae: a review and synthesis

Algae have been used for a century in environmental assessments of water bodies and are now used in countries around the world. This review synthesizes recent advances in the field around a framework for environmental assessment and management that can guide design of assessments, applications of phycology in assessments, and refinements of those applications to better support management decisions. Algae are critical parts of aquatic ecosystems that power food webs and biogeochemical cycling. Algae are also major sources of problems that threaten many ecosystems goods and services when abundances of nuisance and toxic taxa are high. Thus, algae can be used to indicate ecosystem goods and services, which complements how algal indicators are also used to assess levels of contaminants and habitat alterations (stressors). Understanding environmental managers' use of algal ecology, taxonomy, and physiology can guide our research and improve its application. Environmental assessments involve characterizing ecological condition and diagnosing causes and threats to ecosystems goods and services. Recent advances in characterizing condition include site‐specific models that account for natural variability among habitats to better estimate effects of humans. Relationships between algal assemblages and stressors caused by humans help diagnose stressors and establish targets for protection and restoration. Many algal responses to stressors have thresholds that are particularly important for developing stakeholder consensus for stressor management targets. Future research on the regional‐scale resilience of algal assemblages, the ecosystem goods and services they provide, and methods for monitoring and forecasting change will improve water resource management.     

Considerations for the development of a terrestrial index of ecological integrity

Ecological systems are composed of complex biological and physical components that are difficult to understand and to measure. However, effective management actions and policy decisions require information on the status, condition, and trends of ecosystems. Multiple levels of information are needed to make effective decisions and the ideal indicators for measuring ecosystem integrity will incorporate information from multiple dimensions of the ecosystem. A terrestrial index of ecological integrity would be a useful tool for ecosystem managers and decision makers. The ideal requirements of the terrestrial index of ecosystem integrity (TIEI) are that it be comprehensive and multi-scale, grounded in natural history, relevant and helpful, able to integrate concerns from aquatic and terrestrial ecology, and that it be flexible and measurable.The objective of this research is to investigate if an index, or indices, could be developed that would summarize the condition of ecosystems so that changes can be tracked over time and this information utilized as a tool to support environmental decision making.     

典型红树林生态系统藻类多样性及其在生态过程中的作用

藻类是红树林生态系统重要的生物类群, 根据生态习性可分为浮游植物、底栖微藻和大型藻类三个生态类群, 它们在红树林生态系统生物多样性、初级生产、元素循环等方面起着重要作用。但在红树林生态系统中, 关注重点多集中在红树植物和动物, 对其中的藻类重视不够, 且多数研究集中在近20年以及亚洲的红树林区。事实上, 红树林生态系统藻类非常丰富, 其多样性研究有助于深入揭示红树林生态系统的结构与功能。本文介绍了红树林生态系统藻类的组成类群及其重要性, 重点对红树林区浮游植物、底栖硅藻和大型海藻的种类组成、地理分布及其与初级生产力、水质污染、元素循环、碳库形成等生态过程中的作用的研究动态和进展等进行了总结。根据已有研究, 红树林区浮游植物和底栖硅藻的种类数一般为几十到上百种, 其中硅藻在种类和数量上都占绝对优势, 它们是重要的初级生产者、饵料生物和水质污染指示生物; 红树林区底栖大型藻类主要由红藻、绿藻、褐藻、蓝藻组成, 绿藻的种类较多, 红藻在数量上占优势; 藻类是红树林湿地碳库的重要贡献者, 在红树林湿地生态系统碳汇和碳循环中起重要作用。红树林生态系统是个高度动态和异质的系统, 今后应加强红树林藻类多样性的长周期、大尺度变化及不同生境藻类的综合研究, 关注大陆径流和潮汐对藻类多样性和蓝碳的影响, 借助沉积物藻类记录, 探明红树林区藻类的长周期变化, 反演气候变化和人类活动对红树林生态系统的影响过程和机制。     

底栖硅藻应用于河流生态系统健康评价的研究进展

硅藻是水生态系统中最重要的初级生产者之一, 不仅为生态系统中其他消费者提供碳源, 也因分布广泛、种类多、世代时间短等特点, 通常被认为是水环境及生态系统良好的指示生物。文章介绍了河流生态系统健康及生物完整性的概念, 综述了硅藻尤其是底栖硅藻在水生态系统中的自身特点及作用; 概述了硅藻在生物监测中广泛应用的前提: 对环境因子的响应和国内外对硅藻及硅藻指数在河流生态监测中的研究进展; 介绍了广泛应用的硅藻指数及基于硅藻的生物完整性指数的原理及构建方法; 指出了硅藻及硅藻指数在生物监测及评价中可能所存在的问题, 并提出了今后我国在这个领域后期需开展的工作。     

Forest Health Monitoring and Forest Inventory Analysis Programs Monitor Climate Change Effects in Forest Ecosystems

The Forest Health Monitoring (FHM) and Forest Inventory and Analyses (FIA) programs are integrated biological monitoring systems that use nationally standardized methods to evaluate and report on the health and sustainability of forest ecosystems in the United States. Many of the anticipated changes in forest ecosystems from climate change were also issues addressed in sections of FHM's National Technical Report 1991 to 1998. The integrated FHM and FIA monitoring systems are currently establishing baseline conditions (status and change) in most States for many of the expected effects, and are projected to have full implementation for all States and Territories in 2003. These monitoring systems utilize a broad suite of indicators of key ecosystem components and processes that are responsive to many biotic and abiotic stressors, including those anticipated from climate change. These programs will contribute essential information for many decades for many of the anticipated changes in forest ecosystem from increasing carbon dioxide concentrations, changing climatic scenarios, and extreme weather events that are probable in the next 30 to 100 years.     

Ecological indicators for stream restoration success

Exploitation of freshwater resources is essential for sustenance of human existence and alteration of rivers, lakes and wetlands has facilitated economic development for centuries. Consequently, freshwater biodiversity is critically threatened, with stream ecosystems being the most heavily affected. To improve the status of freshwater habitats, e.g. in the context of the European Water Framework Directive and the US Clean Water Act, it is essential to implement the most effective restoration measures and identify the most suitable indicators for restoration success. Herein, several active and passive bioindication approaches are reviewed in light of existing legal frameworks, current targets and applicable implementation of river restoration. Such approaches should move from the use of single biological indicators to more holistic ecological indicators simultaneously addressing communities, multiple life stages and habitat properties such as water quality, substrate composition and stream channel morphology. The proposed Proceeding Chain of Restoration (PCoR) can enable the integration of natural scientific, political and socioeconomic dimensions for restoration of aquatic ecosystems and associated services. Generally, an analysis that combines target species-based active bioindication with community-based passive bioindication and multivariate statistics seems to be most suitable for a holistic evaluation of restoration success, as well as for the monitoring of stream ecosystem health. Since the response of biological communities to changing environmental conditions can differ between taxonomic groups and rivers, assessments at the ecosystem scale should include several levels of biological organisation. A stepwise evaluation of the primary factors inducing disturbance or degradation is needed to integrate increasing levels of complexity from water quality assessments to the evaluation of ecological function. The proposed PCoR can provide a step-by-step guide for restoration ecologists, comprising all planning steps from the determination of the conservation objectives to the use of ecological indicators in post-restoration monitoring.     

小型城市湖泊生态系统预警技术--以武汉市汉阳地区为例

城市湖泊正面临着水体污染和生态系统退化的双重压力 ,对湖泊生态系统的状态进行预警是判定湖泊演化趋势以及制定相应控制对策的重要途径和手段。本文以武汉市汉阳地区的 6个小型城市湖泊为例 ,结合国内外的研究进展 ,从水生生态系统、湖滨生态系统和入湖沟渠生态系统 3方面入手 ,结合生物监测、生物标志物技术 ,综合考虑水文、水质和生态系统以及污染物扩散等因素 ,设计出汉阳地区湖泊生态系统的预警技术体系。该技术体系主要分 5步 :湖泊生态系统现状调研、生物标志物和关键指示因子确定、水质 -生态系统模拟、系统输出和灵敏度检验以及生态系统状态预警及对策、措施     

Roles of benthic algae in the structure,function, and assessment of stream ecosystems affected by acid mine drainage

Tens of thousands of stream kilometers worldwide are degraded by a legacy of acid loads, high metal concentrations, and altered habitat caused by acid mine drainage (AMD) from abandoned underground and surface mines. As the primary production base in streams, the condition of algal‐dominated periphyton communities is particularly important to nutrient cycling, energy flow, and higher trophic levels. Here, we synthesize current knowledge regarding how AMD‐associated stressors affect (i) algal communities and their use as ecological indicators, (ii) their functional roles in stream ecosystems, and (iii) how these findings inform management decisions and evaluation of restoration effectiveness. A growing body of research has found ecosystem simplification caused by AMD stressors. Species diversity declines, productivity decreases, and less efficient nutrient uptake and retention occur as AMD severity increases. New monitoring approaches, indices of biological condition, and attributes of algal community structure and function effectively assess AMD severity and effectiveness of management practices. Measures of ecosystem processes, such as nutrient uptake rates, extracellular enzyme activities, and metabolism, are increasingly being used as assessment tools, but remain in their infancy relative to traditional community structure‐based approaches. The continued development, testing, and implementation of functional measures and their use alongside community structure metrics will further advance assessments, inform management decisions, and foster progress toward restoration goals. Algal assessments will have important roles in making progress toward improving and sustaining the water quality, ecological condition, and ecosystem services of streams in regions affected by the legacy of unregulated coal mining.     

Industrial‐strength ecology: trade‐offs and opportunities in algal biofuel production

Microalgae represent one of the most promising groups of candidate organisms for replacing fossil fuels with contemporary primary production as a renewable source of energy. Algae can produce many times more biomass per unit area than terrestrial crop plants, easing the competing demands for land with food crops and native ecosystems. However, several aspects of algal biology present unique challenges to the industrial‐scale aquaculture of photosynthetic microorganisms. These include high susceptibility to invading aquatic consumers and weeds, as well as prodigious requirements for nutrients that may compete with the fertiliser demands of other crops. Most research on algal biofuel technologies approaches these problems from a cellular or genetic perspective, attempting either to engineer or select algal strains with particular traits. However, inherent functional trade‐offs may limit the capacity of genetic selection or synthetic biology to simultaneously optimise multiple functional traits for biofuel productivity and resilience. We argue that a community engineering approach that manages microalgal diversity, species composition and environmental conditions may lead to more robust and productive biofuel ecosystems. We review evidence for trade‐offs, challenges and opportunities in algal biofuel cultivation with a goal of guiding research towards intensifying bioenergy production using established principles of community and ecosystem ecology.     

A system for lake ecosystem indices

There is a growing awareness of the need to develop a more rational structure for scientific decision-making in the environmental sphere. The aim of this paper is to present an outline to a system for ecosystem indices (or indicators). This work is based on a holistic ecosystem perspective and the aim is to present an overall concept rather than practical results. One of the purposes of ecosystem indices is to give politicians and the general public a more easily understandable account of the environmental status and how it changes. An ecosystem index should be not only simple and concise, scientifically relevant and practical, but also economically feasible. This approach uses several important concepts, like target organisms, target ecosystems, environmental sensitivity, and environmental cost/benefit analyses related to remedial measures. Some of the ideas brought forward in this work may be unrealistic because of the complexities involved in establishing simple, practical and meaningful ecological indices. Still, the benefits of establishing even crude environmental indicators for certain ecosystems are so great, that this path is well worth pursuing.     

Aquatic biodiversity in forests: a weak link in ecosystem services resilience

The diversity of aquatic ecosystems is being quickly reduced on many continents, warranting a closer examination of the consequences for ecological integrity and ecosystem services. Here we describe intermediate and final ecosystem services derived from aquatic biodiversity in forests. We include a summary of the factors framing the assembly of aquatic biodiversity in forests in natural systems and how they change with a variety of natural disturbances and human-derived stressors. We consider forested aquatic ecosystems as a multi-state portfolio, with diverse assemblages and life-history strategies occurring at local scales as a consequence of a mosaic of habitat conditions and past disturbances and stressors. Maintaining this multi-state portfolio of assemblages requires a broad perspective of ecosystem structure, various functions, services, and management implications relative to contemporary stressors. Because aquatic biodiversity provides multiple ecosystem services to forests, activities that compromise aquatic ecosystems and biodiversity could be an issue for maintaining forest ecosystem integrity. We illustrate these concepts with examples of aquatic biodiversity and ecosystem services in forests of northwestern North America, also known as Northeast Pacific Rim. Encouraging management planning at broad as well as local spatial scales to recognize multi-state ecosystem management goals has promise for maintaining valuable ecosystem services. Ultimately, integration of information from socio-ecological ecosystems will be needed to maintain ecosystem services derived directly and indirectly from forest aquatic biota.     

An index of limnological conditions for urban wetlands of Bogotá city,Colombia

The urban wetlands of Bogotá are ecosystems of great importance, yet they are deteriorating. The state of deterioration must be evaluated in order to develop new methods of ecosystem monitoring and conservation. Here we describe the development of an index to assess the ecological health of five urban wetlands and one rural wetland from limnological data. The field phase of this study took place in November 2007 (rainy season) and February 2008 (dry season). Physical and chemical variables of the wetland ecosystems (temperature, dissolved oxygen, pH, conductivity, hardness, chlorides, ammonia, nitrites, nitrates, orthophosphates, and biological oxygen demand) were measured and samples of phytoplankton, periphyton, macroinvertebrates, and aquatic plants (macrophytes) were collected. The indices developed (biotic indices of communities: BI, and limnological conditions index: LICOI) allow classification of wetlands into three categories: those that have “acceptable limnological conditions” (Meridor, Jaboque and Guaimaral), those with “regular limnological conditions” (Santa María del Lago, Juan Amarillo) and those with “poor limnological conditions” (Tibanica). None of the environments studied fit a potential fourth category of “best limnological conditions.” The LICOI is a management tool that can be used to assess changes in wetlands after positive actions (restoration, cleaning, hydraulic management), or negative impacts (depletion, alien species, pollution). It also could allow regular monitoring of wetland evolution and serve as a basis for the development of indices measuring the ecological status of other aquatic environments in Colombia.     

New generation water quality guidelines for ecosystem protection

1. Water quality guidelines are important for the management of water resources. Initially, guidelines focused on quality for domestic drinking water and for agricultural, recreational and industrial purposes. More recently, the emphasis has been on ecosystem protection, as well. 2. This paper discusses the key elements of new risk-based water quality guidelines being developed in Australia and New Zealand, that should lead to more effective management and protection of aquatic ecosystems. 3. There are three essential elements to this new approach: (i) it is ecosystem-based— ideally the guidelines should be, as far as possible, ecosystem-specific; (ii) it is issue-based— the guidelines should focus on the actual issues or problems caused by physical, chemical and biological stressors rather than on the individual indicators, as at present; and (iii) it is risk-based. There is generally great difficulty in deciding whether adverse biological effects will result from various stressors added to an ecosystem. The new approach develops guideline ‘packages’ for each issue and, where possible, for each ecosystem type. Each ‘package’ consists of specified key performance indicators, trigger levels for these indicators (that is, levels which indicate the degree of risk that adverse biological effects may occur), and for high risk situations (where trigger levels are exceeded) a protocol for considering the effect of ecosystem-specific factors in reducing (or enhancing) the biological effects. 4. This paper presents a case study related to a highly relevant aquatic ecosystem issue in Australia, namely the excessive growth of cyanobacteria (blue-green algal blooms), to illustrate how the new risk-based guidelines might be applied.     

Can monitoring data contribute to the biodiversity-ecosystem function debate? Evaluating data from a highly dynamic ecosystem

One of the most controversially discussed topics in current biodiversity-ecosystem function research is the transfer of results from experimental and theoretical studies to natural ecosystems. At the same time, monitoring data on biodiversity are requested as key indicators for the state of an ecosystem in most environmental evaluation frameworks. We analyse two monitoring data sets comprising information on abundance and biomass of macrozoobenthos communities in the German Wadden Sea in order to evaluate how much information monitoring data on biodiversity provide concerning ecosystem functioning and what implications this information (or the lack thereof) has for future monitoring programmes. Our results show a positive correlation between number of species of macrozoobenthos and its standing stock. Despite differences in overall biomass and individual size in different functional groups, this correlation remained consistent for different feeding guilds and therefore is likely to be independent of certain species traits. Moreover, functional turnover analyses indicate that increasing species richness is needed to maintain biomass levels over increasing periods of time. Whereas our data thus corroborate predictions from theory, we could not determine any causal relationships, because monitoring data commonly include only vague proxies for very few functional parameters, in our case standing biomass as a proxy for production. As to the use of diversity as an indicator for ecosystem functioning, we advise that management decisions are to be based on verified causal relationships and therefore strongly suggest the general incorporation of unambiguous proxies for functional parameters in the measuring campaigns of monitoring programmes.     

Multiple Interception Pathways for Resource Utilisation and Increased Ecosystem Resilience

Natural ecosystems consist of multiple pathways for resource capture and energy flow. As landscapes become impacted, the diversity of these pathways is reduced and ecosystem health suffers. Efficient resource processing is essential for successful ecosystem restoration and yet little information is available relating the two issues. Disturbances to terrestrial, marine, and freshwater environments have decreased the complexity of such ecosystems thus reducing their resilience to increases in resource loading from anthropogenic sources. The effects of a reduction in the number of pathways are observed in terminal water bodies where increased levels of nutrients are not successfully intercepted beforehand, and conditions often favour a single phytoplankton pathway, resulting in algal blooms. If a suitable number of pathways is restored, significant amounts of resources may be retained, reducing the impacts on downstream ecosystems. The restoration of functional diversity is likely to provide process redundancy and therefore improve ecosystem resilience to further disturbance. This concept provides a more holistic approach to management strategies that may enhance resource interception, while restoring habitat and biological diversity.     

Carrion cycling in food webs: comparisons among terrestrial and marine ecosystems

In light of current global changes to ecosystem function (e.g. climate change, trophic downgrading, and invasive species), there has been a recent surge of interest in exploring differences in nutrient cycling among ecosystem types. In particular, a growing awareness has emerged concerning the importance of scavenging in food web dynamics, although no studies have focused specifically on exploring differences in carrion consumption between aquatic and terrestrial ecosystems. In this forum we synthesize the scavenging literature to elucidate differences in scavenging dynamics between terrestrial and marine ecosystems, and identify areas where future research is needed to more clearly understand the role of carrion consumption in maintaining ecosystem function within each of these environments. Although scavenging plays a similar functional role in terrestrial and aquatic food webs, here we suggest that several fundamental differences exist in scavenging dynamics among these ecosystem types due to the unique selection pressures imposed by the physical properties of water and air. In particular, the movement of carcasses in marine ecosystems (e.g. wave action, upwelling, and sinking) diffuses biological activity associated with scavenging and decomposition across large, three‐dimensional spatial scales, creating a unique spatial disconnect between the processes of production, scavenging, and decomposition, which in contrast are tightly linked in terrestrial ecosystems. Moreover, the limited role of bacteria and temporal stability of environmental conditions on the sea floor appears to have facilitated the evolution of a much more diverse community of macrofauna that relies on carrion for a higher portion of its nutrient consumption than is present in terrestrial ecosystems. Our observations are further discussed as they pertain to the potential impacts of climate change and trophic downgrading (i.e. removal of apex consumers from ecosystems) on scavenging dynamics within marine and terrestrial ecosystems.     

Understorey environments influence functional diversity in tank‐bromeliad ecosystems

1. A substantial fraction of the freshwater available in neotropical forests is impounded within the rosettes of bromeliads that form aquatic islands in a terrestrial matrix. The ecosystem functioning of bromeliads is known to be influenced by the composition of the contained community but it is not clear whether bromeliad food webs remain functionally similar against a background of variation in the understorey environment. 2. We considered a broad range of environmental conditions, including incident light and incoming litter, and quantified the distribution of a very wide range of freshwater organisms (from viruses to macroinvertebrates) to determine the factors that influence the functional structure of bromeliad food webs in samples taken from 171 tank‐bromeliads. 3. We observed a gradient of detritus‐based to algal‐based food webs from the understorey to the overstorey. Algae, rotifers and collector and predatory invertebrates dominated bromeliad food webs in exposed areas, whereas filter‐feeding insects had their highest densities in shaded forest areas. Viruses, bacteria and fungi showed no clear density patterns. Detritus decomposition is mainly due to microbial activity in understorey bromeliads where filter feeders are the main consumers of microbial and particulate organic matter (POM). Algal biomass may exceed bacterial biomass in sun‐exposed bromeliads where amounts of detritus were lower but functional diversity was highest. 4. Our results provide evidence that tank‐bromeliads, which grow in a broad range of ecological conditions, promote aquatic food web diversity in neotropical forests. Moreover, although bromeliad ecosystems have been categorised as detritus‐based systems in the literature, we show that algal production can support a non‐detrital food web in these systems.     

An evolving role for ecological indicators: From documenting ecological conditions to monitoring drivers and policy responses

Monitoring the health of ecosystems is imperative to achieve sustainability. In this, ecological indicators have a crucial and evolving role to play. Although indicators are vital to monitoring the state and trends of ecosystems and the consequences of anthropogenic pressures, they may not lead to necessary action unless they are coupled with identification and monitoring of drivers. This will provide a basis for evaluating the effectiveness of policy responses, thus providing information that is actionable by policy makers and the public. We argue that expanding the role of indicators will render them far more effective as a resource for combating ecosystem degradation. Using the Baltic Sea as an example we analyse the nature of this challenge and provide concrete solutions to problems hindering the effectiveness of ecological indicator use in restoring health to large-scale ecosystems.     

Indicators of biodiversity and ecosystem services: a synthesis across ecosystems and spatial scales

According to the Millennium Ecosystem Assessment, common indicators are needed to monitor the loss of biodiversity and the implications for the sustainable provision of ecosystem services. However, a variety of indicators are already being used resulting in many, mostly incompatible, monitoring systems. In order to synthesise the different indicator approaches and to detect gaps in the development of common indicator systems, we examined 531 indicators that have been reported in 617 peer‐reviewed journal articles between 1997 and 2007. Special emphasis was placed on comparing indicators of biodiversity and ecosystem services across ecosystems (forests, grass‐ and shrublands, wetlands, rivers, lakes, soils and agro‐ecosystems) and spatial scales (from patch to global scale). The application of biological indicators was found most often focused on regional and finer spatial scales with few indicators applied across ecosystem types. Abiotic indicators, such as physico‐chemical parameters and measures of area and fragmentation, are most frequently used at broader (regional to continental) scales. Despite its multiple dimensions, biodiversity is usually equated with species richness only. The functional, structural and genetic components of biodiversity are poorly addressed despite their potential value across habitats and scales. Ecosystem service indicators are mostly used to estimate regulating and supporting services but generally differ between ecosystem types as they reflect ecosystem‐specific services. Despite great effort to develop indicator systems over the past decade, there is still a considerable gap in the widespread use of indicators for many of the multiple components of biodiversity and ecosystem services, and a need to develop common monitoring schemes within and across habitats. Filling these gaps is a prerequisite for linking biodiversity dynamics with ecosystem service delivery and to achieving the goals of global and sub‐global initiatives to halt the loss of biodiversity.