Helen R. Bayliss

Effectiveness of engineered in‐stream structure mitigation measures to increase salmonid abundance: a systematic review

Engineered in-stream structures are often installed to increase salmonid abundance, either for commercial gain in fisheries or for conservation purposes in degraded habitats. Having been in widespread use for the last 80 years, at an estimated cost of hundreds of millions of U.S. dollars each year, the effectiveness of these structures is still widely debated in the literature. Many studies of varying quality have been undertaken that attempt to address this issue, but it has proved difficult for practitioners to develop a consensus regarding the utility of these structures, despite their continued use. Systematic review methodology was used to formally synthesize empirical evidence regarding the effectiveness of engineered in-stream structures as a management tool to increase salmonid abundance. Meta-analysis shows that evidence regarding the effectiveness of in-stream devices is equivocal. Heterogeneity is significant both for population size and local habitat preference. This heterogeneity is related to stream width, with in-stream devices being less effective in larger streams. Consequently, widespread use of in-stream structures for restoration, particularly in larger streams, is not supported by the current scientific evidence base.

Systematic searching for environmental evidence using multiple tools and sources

BackgroundThis paper provides guidance about how to plan, prepare, conduct, report, amend or update a systematic search. It aims to contribute to a new version of the Collaboration for Environmental Evidence (CEE) Guidelines for Systematic Reviews in Environmental Management, and the methods we describe are likely to be broadly applicable across a wider range of topics. In evidence synthesis, searches are expected to be repeatable, fit for purpose, with minimum biases, and to collate a maximum number of relevant articles. Failing to include relevant information in an evidence synthesis may lead to inaccurate or skewed conclusions and/or changes in conclusions as soon as the omitted information is added.MethodThe paper takes into account similar documents produced by the Cochrane Collaboration and the Campbell Collaboration, including necessary adjustments for environmental policy and management, and the current version of the CEE Guidelines (version 4.2, 2013). Where possible this guidance is based on evidence from research, and in its absence on expert opinion and experience.ResultsHere we aim to provide guidance on the optimal search structure as the basis on which any evidence synthesis should be built.ConclusionIt is aimed at all those who intend to conduct systematic evidence synthesis, including reviews and Ph.D. thesis.

Clarification on the applicability of systematic reviews

© The Ecological Society of America www.frontiersinecology.org vance against a set of predefined inclusion criteria set out in the protocol, at title, abstract, and then fulltext levels; critically appraising identified studies for their robustness and potential for bias using a planned appraisal strategy; extracting metadata and study results; synthesizing the findings of all included studies in a quantitative way where possible; and drafting a highly detailed report of the review – including lists of excluded studies and reasons – which is then peer-reviewed and published (Pullin and Stewart 2006). Since its relatively recent introduction to the environmental sciences, the method has become accepted as an established form of publication (Lortie 2014) and is now widely viewed as a gold standard in evidence synthesis, attracting substantial interest and investment from major international funders, such as the Science and Technical Advisory Panel of the United Nations (eg Pullin et al. 2013). More than 60 systematic reviews have been published in the environmental sciences (www.environmentalevidence.org), and some 6000 systematic reviews covering medical topics have been published in the Cochrane Library (www.thecochranelibrary.com). Dafforn et al. stated that a systematic review was not possible due to the multidisciplinary nature and the high volume of gray literature of their research topic. Multidisciplinary systematic reviews may face additional challenges, including searching databases from different disciplines to ensure adequate topic coverage, but such reviews are increasingly common: for instance, between environmental management and development (eg Waddington et al. 2014) and biodiversity protection and human well-being (eg Pullin et al. 2013). A further major strength of systematic reviews relative to traditional reviews is that the former make considerable efforts to identify relevant studies from the gray literature in an attempt to counter publication bias and ensure that other forms of evidence, such as industry Clarification on the applicability of systematic reviews In their recent article, Dafforn et al. (Front Ecol Environ 2015; 13[2]: 82–90) reviewed the literature on marine urbanization to produce a conceptual framework for the design of multifunctional marine artificial structures. Their review highlighted the rapid increase in marine urbanization and the well-documented ecological impacts of marine infrastructure. The authors stated that “a systematic review was not possible given that much of the relevant literature crosses scholarly disciplines and is located in books, conference proceedings, and gray literature that would not have appeared in searches”. While we fully agree that such a topic poses challenges in terms of searching across subject domains and incorporating the substantial utility of gray literature, we felt compelled to draw attention to common misconceptions regarding systematic reviews. Systematic reviews were developed within the medical discipline around 25 years ago and have since been adapted for use in a variety of subjects, including environmental management and conservation (Pullin and Stewart 2006). Systematic reviews aim to provide reliable summaries of evidence in a transparent, objective, and repeatable manner: something that would undoubtedly benefit the topic discussed in Dafforn et al.’s review. The systematic review approach improves on the traditional review process in various ways. First, an a priori plan for the systematic review is established in a protocol document, which is peer-reviewed and published for each review. The review then proceeds according to this plan: searching for literature from a wide array of sources using a predetermined search strategy that has been tested by the reviewers to ensure that it returns known relevant research; screening all identified search records for relereports, are detected. In summary, Dafforn et al. may have had many reasons not to undertake a systematic review, a task that is often considered as resource-intensive and time-consuming. However, the multidisciplinary nature of their chosen topic and the importance of including gray literature are good reasons to embrace the robustness and transparency of the systematic review, which not only is amenable to addressing this type of question but also offers several methodological advantages over traditional narrative reviews. Neal R Haddaway and Helen R Bayliss MISTRA EviEM, Royal Swedish Academy of Sciences, Stockholm, Sweden (neal_haddaway@hotmail.com); Centre for Evidence-Based Conservation, Bangor University, Bangor, UK

Effectiveness of management interventions for control of invasive Common ragweed Ambrosia artemisiifolia : a systematic review protocol

BackgroundAlien species are severely impacting the environment, public health and socioeconomy at a global scale. Their management is thus of crucial importance and the subject of intensive research efforts. Common ragweed Ambrosia artemisiifolia L. is an alien species with negative impacts on agriculture, human health and biodiversity. It is a highly allergenic, wind-pollinated herb native to North America that was first introduced to Europe during the seventeenth century. It has since become widespread and is currently in an ongoing phase of rapid spread and increasing abundance. Several management approaches are currently implemented and effective control of the species can have strong socioeconomic benefits. However, evidence for management effectiveness is scattered and has not yet been synthesised systematically. For these reasons, we here aim to systematically review the evidence to assess (a) what is the effectiveness of management options used for control of Common ragweed Ambrosia artemisiifolia and (b) what is the effect of confounding factors such as habitat, climate and frequency and timing of treatment?MethodsThis protocol specifies the methods for conducting a systematic review to answer the specified questions. Search terms relating to the population and the intervention (type of management) will be combined and searched in a range of databases and other sources. Specific inclusion criteria are (i) any population of Ambrosia artemisiifolia at any habitat including populations in agricultural settings and such used for experimental research at any geographic location (including its native range), (ii) any physical, chemical, biological or combined management action; (iii) direct outcome measures including change in coverage, abundance, biomass, survival, reoccurrence, biology (e.g. growth, height, leaf area) or pollen production. The wide range of quality of primary literature will be evaluated with a tailored system for assessing susceptibility to bias and the reliability of the studies. If extracted data are suitable for quantitative synthesis, we aim to calculate effect sizes and conduct meta-analyses.

Updating and amending systematic reviews and systematic maps in environmental management

Systematic reviews and systematic maps aim to provide an overview of the best available evidence to inform research, policy and practice. However, like any form of review, they will require updating periodically to ensure that the most recent evidence has been incorporated. Here we outline two types of review revisions as recognised in medicine: updates and amendments. Updates involve a search for new studies, expanding the evidence base through time. Any other change (e.g. in screening or synthesis) or correction to the original report is an amendment. Decisions as to whether/when it is appropriate to undertake an update or amendment must be made on a case-by-case basis, considering issues such as the reliability and scope of the existing review or map, likely volume of new evidence, resources available, and the likely value of including new information. Careful, consistent reporting is necessary to ensure transparency and repeatability, particularly where there are deviations from the original methods, and authors should highlight key advances relative to the original report. Updating environmental systematic reviews and maps will be an increasingly important activity as the numbers of both primary studies and synthetic reports in the literature continue to grow.