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.     

Learning from scientific literature: Can indicators for measuring success be standardized in “on the ground” restoration?

The Society for Ecological Restoration (SER) Primer identifies key ecosystem attributes for evaluating restoration outcome. Broad attribute categories could be necessary due to the large variety of restoration projects, but could make overall evaluations and assessments challenging and might hamper the development of sound and successful restoration. In this study we carry out a systematic review of scientific papers addressing evaluation of restoration outcome. We include 104 studies published after 2010 from Europe or North America, representing different types of restoration projects in terrestrial and freshwater ecosystems. We explore the main ecological and socioeconomic attributes used to evaluate restoration outcome, and related indicators and specific methods applied to measure this, in relation to ecosystem and type of restoration project. We identify a wide range of indicators within each attribute, and show that very different methods are employed to measure them. This complexity reduces the opportunity for meaningful comparison and standardization of evaluation of restoration outcome, within and between ecosystems. Socioeconomic indicators are rarely used to evaluate restoration outcome, and studies including both ecological and socioeconomic indicators are nearly absent. Based on our findings we discuss whether standardization and streamlining of indicators is useful to improve the evaluation of “on the ground” restoration, or if this is not appropriate given the diversity of goals and ecosystems involved. Species‐specific traits are used in many projects and should be considered as an addition to the original SER attributes. Furthermore, we discuss the potential for restoration evaluation that encompasses not only assessment of ecological but also socioeconomic indicators.     

淡水湖泊生态系统退化驱动因子及修复技术研究进展

目前我国多数淡水湖泊污染、退化问题非常严重,诸多修复技术也已初见成效。影响淡水湖泊生态系统退化的驱动因子众多,既有生物因素也有非生物因素,它们之间相互联系,相互作用,且作用机理错综复杂。首先介绍了淡水湖泊生态系统退化的含义及形式;其次,分析、总结了淡水湖泊生态系统退化的驱动因子,从退化的生态学完整性意义和退化修复的技术手段上看,淡水湖泊生态系统主要受物理、化学和生物三大驱动因子影响,且基本遵循"环境变化-驱动力-压力(阈值)-状态-响应"原理;再次,在厘清湖泊生态系统退化驱动原理的基础上,从淡水湖泊生态系统功能模块和湖泊生态系统修复实践经验总结的角度出发,构建了淡水湖泊生态系统修复模块技术体系,并就湖泊富营养化和湖滨湿地生态系统退化修复的技术进行了讨论和对比;最后,对淡水湖泊生态系统修复的环境变化驱动因子的作用机制、作用途径和修复技术的长效机制等方面进行了展望。     

A novel bacterial community index to assess stream ecological health

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Long-Term Monitoring and Evaluation of the Lower Red River Meadow Restoration Project, Idaho, U.S.A.

Although public and financial support for stream restoration projects is increasing, long‐term monitoring and reporting of project successes and failures are limited. We present the initial results of a long‐term monitoring program for the Lower Red River Meadow Restoration Project in north‐central Idaho, U.S.A. We evaluate a natural channel design’s effectiveness in shifting a degraded stream ecosystem onto a path of ecological recovery. Field monitoring and hydrodynamic modeling are used to quantify post‐restoration changes in 17 physical and biological performance indicators. Statistical and ecological significance are evaluated within a framework of clear objectives, expected responses (ecological hypotheses), and performance criteria (reference conditions) to assess post‐restoration changes away from pre‐restoration conditions. Compared to pre‐restoration conditions, we observed ecosystem improvements in channel sinuosity, slope, depth, and water surface elevation; quantity, quality, and diversity of in‐stream habitat and spawning substrate; and bird population numbers and diversity. Modeling documented the potential for enhanced river–floodplain connectivity. Failure to detect either statistically or ecologically significant change in groundwater depth, stream temperature, native riparian cover, and salmonid density is due to a combination of small sample sizes, high interannual variability, external influences, and the early stages of recovery. Unexpected decreases in native riparian cover led to implementation of adaptive management strategies. Challenges included those common to most project‐level monitoring—isolating restoration effects in complex ecosystems, securing long‐term funding, and implementing scientifically rigorous experimental designs. Continued monitoring and adaptive management that support the establishment of mature and dense riparian shrub communities are crucial to overall success of the project.     

Ecological Restoration of Headwaters in a Rural Landscape (Normandy,France): A Passive Approach Taking Hedge Networks into Account for Riparian Tree Recruitment

The safeguard of riparian ecosystems is a major field of study in the understanding and maintenance of the ecological health of rivers. Vegetation communities found on these ecotones ensure essential functions such as limitation of river bank erosion and protection of rivers from pollutants. The aim of our study is to investigate the potential for natural regeneration of trees on river banks after passive restoration. We have also studied the influence of landscape on recolonization through the analysis of the influence of hedge networks. Our study takes place on headwaters in Normandy (France) on Vallée‐Aux‐Berges, a stream, which has been passively restored for the last 6 years. As passive restoration removes stresses (heavy trampling and grazing) caused by cattle on river banks, we expect it to help the growth of natural plant communities. The condition of this stream—from the start of restoration work to the present—is compared to another one in the same catchment considered to be ecologically healthy. Our results suggest that passive restoration leads to an increase in tree cover on river banks and contributes to the improvement of the banks' physical integrity. Landscape structure seems to be a major factor for this recolonization: the more the stream is surrounded by hedge networks, the more the recolonization by trees on banks is effective. These results indicate that the influence of landscape structure should be considered in future restoration management in similar headwaters.     

Restoration goals: Why are fauna still overlooked in the process of recovering functioning ecosystems and what can be done about it?

Despite the evidence that fauna play complex and critical roles in ecosystems (e.g. pollination and nutrient cycling) and the knowledge that they need to be considered in restoration, fauna often remain poorly represented in restoration goal setting, monitoring and assessments of restoration success. Fauna clearly are integral to the aspirations of achieving full ecosystem recovery. However, over‐reaching assumptions about the unassisted return of fauna to restored sites, low investment in fauna monitoring, and minimal consideration of the requirements for fauna monitoring in regulatory guidance and standards appear to have led to the historically vegetation‐centric approaches to rehabilitation and ecological restoration. We argue that ecological complexities render assumptions of unassisted fauna return inappropriate in many situations and may represent a missed opportunity to enhance ecological outcomes and improve restoration trajectories. We advocate for greater consideration of fauna as facilitators of ecological restoration and, particularly for well‐funded projects, for monitoring to place greater emphasis on examining the behaviour and resilience of restored fauna communities. There is a clear need for both industry and regulators to recognise that fauna can be crucial facilitators of restoration and appreciate that the return and monitoring of functional faunal communities can be costly, challenging and may require detailed study across a wide range of taxonomic groups. Failure to advance from business as usual models may risk leaving a legacy of ostensibly functional, but biodiversity‐depauperate, restored ecosystems.     

Monitoring attributes for ecological restoration in Latin America and the Caribbean region

Ecological restoration is becoming mainstreamed worldwide but target ecosystems' responses to restorative interventions are not sufficiently monitored, in terms of the wide range of ecological, social, and economic attributes available. In order to highlight and better understand this problem, we conducted a literature review of the ecological, social, and economic attributes cited in the scientific literature used for monitoring the success of ecological restoration projects in Latin America and the Caribbean region, where no regional study of this kind has previously been conducted. In 84 of the 91 articles retained for the study, ecological indicators were evaluated, while only seven articles included measurements of socioeconomic indicators. Regarding the Society for Ecological Restoration Primer attributes of restored ecosystems, we only found indicators measuring attributes 1–6, with attribute 1 (species assemblages) predominating (73%), followed by physical conditions (54%) and ecological functions (51%). Brazil was the country in the region where most monitoring was being carried out (51% of the articles), and tropical rainforest (33%) and tropical dry forest (25%) were the ecosystem types where ecological restoration was most frequently monitored. Highly vulnerable ecosystems such as mangroves and paramos were underrepresented. Attributes related to ecosystem stability or to governance and education of communities were not monitored at all. More real long‐term monitoring, instead of chronosequences, is needed, especially where understanding socioeconomic implications of, and barriers to, effective ecological restoration is a top priority.     

Ecological indicators for assessing ecological success of forest restoration: a world review

Restoration is increasingly being used to reverse degradation and destruction of forest ecosystems. With increasing investment in restoration, there is an urgent need to develop effective programs to assess treatment efficacy and effects. We conducted a global review of forest restoration assessments, in order to identify geographic trends in the locations where assessments have been implemented and the specific ecological attributes (ecosystem composition, structure, and function) and indicators being used to measure effects. We found that the number of forest restoration assessments varied by region and was not related to degree of degradation or restoration need. Some regions, like Africa, which have experienced high rates of forest loss and degradation, had few assessments. The majority (43%) of assessments included indicators for only two of three key ecological attributes (composition‐structure or composition‐function) and assessments on average used fewer than three indicators per attribute. The most commonly employed indicators for composition were richness and abundance of plant species and for structure were height and diameter of trees, variables that are generally relatively easy to measure. The use of functional indicators has been increasing over time and they are now more commonly used than structural indicators. The most common functional indicators were soil functions. Most investigators evaluated treatment effects for 6–10 years after implementation. Our findings related to gaps in analysis of ecological indicators can serve as a guide for developing monitoring and assessment protocols for current global forest restoration initiatives by 2020–2030.     

Meta‐Analysis of Lost Ecosystem Attributes in Urban Streams and the Effectiveness of Out‐of‐Channel Management Practices

Urban development is a leading cause of stream impairment that reduces biodiversity and negatively affects ecosystem processes and habitat. Out‐of‐stream restoration practices, such as stormwater ponds, created wetlands, and restored riparian vegetation, are increasingly implemented as management strategies to mitigate impacts. However, uncertainty exists regarding how effectively they improve downstream ecosystems because monitoring is uncommon and results are typically reported on a case‐by‐case basis. We conducted a meta‐analysis of literature and used response ratios to quantify how downstream ecosystems change in response to watershed development and to out‐of‐stream restoration. Biodiversity in unrestored urban streams was 47% less than that in reference streams, and ecological communities, habitat, and rates of nutrient cycling were negatively affected as well. Mean measures of ecosystem attributes in restored streams were significantly greater than, and 156% of, those in unrestored urban streams. Measures of biodiversity in restored streams were 132% of those in unrestored urban streams, and indices of biotic condition, community structure, and nutrient cycling significantly improved. However, ecosystem attributes and biodiversity at restored sites were significantly less than, and only 60% and 45% of, those in reference streams, respectively. Out‐of‐stream management practices improved ecological conditions in urban streams but still failed to restore reference stream conditions. Despite statistically significant improvements, assessing restoration success remains difficult due to few comparisons to reference sites or to clearly defined targets. These findings can inform future monitoring, management, and development strategies and highlight the need for preventative actions in a watershed context.     

The ecological importance of crocodylians: towards evidence‐based justification for their conservation

Large‐bodied predators are well represented among the world's threatened and endangered species. A significant body of literature shows that in terrestrial and marine ecosystems large predators can play important roles in ecosystem structure and functioning. By contrast, the ecological roles and importance of large predators within freshwater ecosystems are poorly understood, constraining the design and implementation of optimal conservation strategies for freshwater ecosystems. Conservationists and environmentalists frequently promulgate ecological roles that crocodylians are assumed to fulfil, but often with limited evidence supporting those claims. Here, we review the available information on the ecological importance of crocodylians, a widely distributed group of predominantly freshwater‐dwelling, large‐bodied predators. We synthesise information regarding the role of crocodylians under five criteria within the context of modern ecological concepts: as indicators of ecological health, as ecosystem engineers, apex predators, keystone species, and as contributors to nutrient and energy translocation across ecosystems. Some crocodylians play a role as indicators of ecosystem health, but this is largely untested across the order Crocodylia. By contrast, the role of crocodylian activities in ecosystem engineering is largely anecdotal, and information supporting their assumed role as apex predators is currently limited to only a few species. Whether crocodylians contribute significantly to nutrient and energy translocation through cross‐ecosystem movements is unknown. We conclude that most claims regarding the importance of crocodylians as apex predators, keystone species, ecosystem engineers, and as contributors to nutrient and energy translocation across ecosystems are mostly unsubstantiated speculation, drawn from anecdotal observations made during research carried out primarily for other purposes. There is a paucity of biological research targeted directly at: understanding population dynamics; trophic interactions within their ecological communities; and quantifying the short‐ and long‐term ecological impacts of crocodylian population declines, extirpations, and recoveries. Conservation practices ideally need evidence‐based planning, decision making and justification. Addressing the knowledge gaps identified here will be important for achieving effective conservation of crocodylians.     

Australian water quality guidelines: a new approach for protecting ecosystem health

The Australian and New Zealand Environment and Conservation Council (ANZECC) and the Australian Water Resources Council (AWRC) have developed a National Water Quality Management Strategy which seeks to ensure that the nation's water resources are managed on a sustainable basis. An important element of this strategy are the Australian Water Quality Guidelines which focus on the protection of Australian freshwater and marine ecosystems. Here the aim is to protect biodiversity and maintain the ecological integrity of each marine and freshwater resource. Specific guidelines have been formulated in terms of key indicators of quality, with a single reference value or ranges of reference values provided for guidance. For those indicators where ranges are provided, it is the expectation that State environmental and resource management agencies will undertake local, site-specific investigations of their own systems to define the specific levels to be adopted. For the first time, specific and quantitative biological indicators have been introduced; these are species richness, species composition, primary production, and ecosystem function.As Australia progresses towards broader, more holistic, ecologically-based management of the nation's water resources, the present water quality guidelines must be extended to ecosystem or environmental guidelines, where the maintenance of adequate water quality is seen as only one (albeit important) component. Other considerations must include habitat protection, sediment quality, and stream flow maintenance. This increased emphasis on more ecologically-focused management of Australia's inland and coastal waters will present a number of challenges for the three major groups involved: the community, the managers, and the researchers. These challenges are discussed.Based on a paper presented at a Workshop on Biological Assessment of Aquatic Ecosystem Health, Sydney, 1–2 October 1992.     

Restoration of the Kissimmee River: A Conceptual Model of Past and Present Fish Communities and Its Consequences for Evaluating Restoration Success

Efforts to restore fish communities of the Kissimmee River will require carefully defined criteria for assessing success. A goal of regaining communities mirroring those in the historical river may not be an appropriate target because the ecological conditions of the river before channelization are poorly known. The Kissimmee River is in a biogeographic region historically low in fish diversity, and no comparable rivers in that region remain substantially unaltered by human activity to permit their use as reference sites indicative of conditions in the Kissimmee before channelization. I propose alternative criteria for assessing restoration success emphasizing expectations for ecosystem function in similar floodplain rivers. Assessing ecosystem function will be less simple than assessing criteria such as fish condition or density of selected species. But criteria based solely on fish-population characteristics cannot be justified quantitatively. Information integrated from several levels of biotic organization (individuals, populations, communities, and systems) should be drawn upon in making conclusions about restoration success. I develop a conceptual model to outline aspects of ecosystem function that could serve as a basis for evaluation of the restoration of fish communities of the Kissimmee River. The model focuses on the dynamics of the flux of floodplain-channel nutrients and the movement of larvae, juvenile, and adult fishes and macroinvertebrates. The present community may be dominated more by species tolerant of low-oxygen conditions, such as gar and bowfin, than the restored community will be. I propose that nest sites may be the limiting recruitment success of substrate spawning species in the channelized river and that these species, including sunfish and large-mouth bass, will increase in abundance after restoration. Also, species relying on floodplain habitats, including sun-fish species, darters, and some minnows, may also increase in frequency with restoration of floodplain-channel hydro-logical conditions and habitats. The observation that no species are known to have disappeared from the Kissimmee River, and its relatively simple community structure compared to rivers of comparable size elsewhere, are encouraging for prospects of successful restoration.     

The need for broader ecological and socioeconomic tools to evaluate the effectiveness of coral restoration programs

Coral reef restoration initiatives are burgeoning in response to the need for novel management strategies to address dramatic global declines in coral cover. However, coral restoration programs typically lack rigor and critical evaluation of their effectiveness. A review of 83 peer‐reviewed papers that used coral transplantation for reef restoration reveals that growth and survival of coral fragments were the most widely used indicators of restoration success, with 88% of studies using these two indicators either solely (55%) or in combination with a limited number of other ecological factors (33%). In 53% of studies, reef condition was monitored for 1 year or less, while only 5% of reefs were monitored for more than 5 years post‐transplantation. These results highlight that coral reef restoration science has focused primarily on short‐term experiments to evaluate the feasibility of techniques for ecological restoration and the initial establishment phase post‐transplantation, rather than on longer‐term outcomes for coral reef communities. Here, we outline 10 socioecological indicators that comprehensively evaluate the effectiveness of coral reef restoration across the four pillars of sustainability (i.e. environmental, sociocultural, governance, and economic contributions to sustainable communities). We recommend that evaluations of the effectiveness of coral restoration programs integrate ecological indicators with sociocultural, economic, and governance considerations. Assessing the efficacy of coral restoration as a tool to support reef resilience will help to guide future efforts and ensure the sustainable maintenance of reef ecosystem goods and services.     

Beyond the green: assessing quarry restoration success through plant and beetle communities

In assessing the effectiveness of ecological restoration actions, outcomes evaluation using a multi‐taxa approach can greatly contribute to a clearer understanding of their success/failure. Since comprehensive biodiversity assessments are rarely possible, choosing taxa groups that are indicative of the ecosystem's structural and functional recovery is of major importance. Our goal was to evaluate the success of revegetation actions performed in a Mediterranean limestone quarry, using plants and epigean beetles as indicators. We compared their abundance, diversity, and community composition between revegetated sites aged 5, 13, and 19 years and a natural reference. Total plant cover significantly increased with restoration age and quickly reached reference values. However, native woody species cover dropped in the oldest site, while non‐native species became dominant. The abundance of beetles was always lower in restoration sites when compared to the reference, increasing with age, although not significantly. The richness of both plant species and beetle families was lower in restoration sites and did not show any trend towards the reference values. Finally, using nonmetric multidimensional scaling, the composition of plant and beetle communities from restoration sites showed a clear separation from the reference. Restoration efforts have successfully modified post‐quarry sites, but considerable differences remain, probably largely related to the use of the non‐native species Pinus halepensis in restoration plans. P. halepensis high cover in restoration sites greatly affects the structure of the ecosystem, and most likely its functioning too, as well as related ecosystem services, causing divergence from the reference values and compromising restoration success.     

The Ability of Aquatic Macrophytes to Assess Fish Farm Pollution in Two Salmon Rivers

The wastewater from freshwater fish farming is responsible for important water quality modifications in receiving ecosystems. These point source pollution cause local problems for the management of the freshwater environment, especially in salmon rivers. The aim of this paper is to study the relationship between plant communities and environmental factors in two rivers basins on which seven fish farms are located and to assess the relative part of water pollution compared to other environmental factors involved in water plant distribution. The disturbance due to fish farming wastewater increased both richness and diversity of aquatic plant communities and modified the distribution of 11 aquatic macrophytes. Nevertheless, the main factors involved in the aquatic plant distribution in the whole data set were not the location upstream or downstream from one point source pollution but the belonging to one river system and the habitat physical features. Relevant prediction of macrophytic communities is a useful tool for bioindication purposes but several groups of variables that manifest themselves at different spatial levels must be considered.     

Promoting social and environmental justice to support Indigenous partnerships in urban ecosystem restoration

Urban ecological restoration typically employs western science approaches to restore degraded ecosystems. As yet, few restoration groups acknowledge the history of these degraded urban sites, despite connections, past and present, that root Indigenous Peoples (and others) in these lands. Here, we promote partnership with Indigenous communities from project inception and present two successful case studies from Aotearoa New Zealand. We specifically note that partnering and building relationships with Indigenous communities in restoration efforts require recognition of power inequalities and injustices. We consider success to include both restoration of ecological function and biodiversity and reconnection of all communities to urban ecosystems.     

A conceptual framework for urban ecological restoration and rehabilitation

Urban greenspace has gained considerable attention during the last decades because of its relevance to wildlife conservation, human welfare, and climate change adaptation. Biodiversity loss and ecosystem degradation worldwide require the formation of new concepts of ecological restoration and rehabilitation aimed at improving ecosystem functions, services, and biodiversity conservation in cities. Although relict sites of natural and semi-natural ecosystems can be found in urban areas, environmental conditions and species composition of most urban ecosystems are highly modified, inducing the development of novel and hybrid ecosystems. A consequence of this ecological novelty is the lack of (semi-) natural reference systems available for defining restoration targets and assessing restoration success in urban areas. This hampers the implementation of ecological restoration in cities. In consideration of these challenges, we present a new conceptual framework that provides guidance and support for urban ecological restoration and rehabilitation by formulating restoration targets for different levels of ecological novelty (i.e., historic, hybrid, and novel ecosystems). To facilitate the restoration and rehabilitation of novel urban ecosystems, we recommend using established species-rich and well-functioning urban ecosystems as reference. Such urban reference systems are likely to be present in many cities. Highlighting their value in comparison to degraded ecosystems can stimulate and guide restoration initiatives. As urban restoration approaches must consider local history and site conditions, as well as citizens’ needs, it may also be advisable to focus the restoration of strongly altered urban ecosystems on selected ecosystem functions, services and/or biodiversity values. Ecosystem restoration and rehabilitation in cities can be either relatively inexpensive or costly, but even expensive measures can pay off when they effectively improve ecosystem services such as climate change mitigation or recreation. Successful re‐shaping and re-thinking of urban greenspace by involving citizens and other stakeholders will help to make our cities more sustainable in the future.     

Integrative freshwater ecology and biodiversity conservation

Freshwater ecosystems provide goods and services of critical importance to human societies, yet they are among the most heavily altered ecosystems with an overproportional loss of biodiversity. Major threats to freshwater biodiversity include overexploitation, water pollution, fragmentation, destruction or degradation of habitat, and invasions by non-native species. Alterations of natural flow regimes by man-made dams, land-use changes, river impoundments, and water abstraction often have profound impacts on lotic communities. An understanding of the functional interactions and processes in freshwater ecosystems presents a major challenge for scientists, but is crucial for effective and sustainable restoration. Most conservation approaches to date have considered single species or single level strategies. In contrast, the concept of ‘Integrative Freshwater Ecology and Biodiversity Conservation’ (IFEBC) proposed herein addresses the interactions between abiotic and biotic factors on different levels of organization qualitatively and quantitatively. It consequently results in a more holistic understanding of biodiversity functioning and management. Core questions include modeling of the processes in aquatic key habitats and their functionality based on the identification and quantification of factors which control the spatial and temporal distribution of biodiversity and productivity in aquatic ecosystems. The context and importance of research into IFEBC is illustrated using case studies from three major areas of research: (i) aquatic habitat quality and restoration ecology, (ii) the genetic and evolutionary potential of aquatic species, and (iii) the detection of stress and toxic effects in aquatic ecosystems using biomarkers. In conclusion, our understanding of the functioning of aquatic ecosystems and conservation management can greatly benefit from the methodological combination of molecular and ecological tools.