BACKGROUND Eutrophication of freshwater ecosystems resulting from nitrogen and phosphorus pollution is a major stressor across the globe. Despite recognition by scientists and stakeholders of the problems of nutrient pollution, rigorous synthesis of scientific evidence is still needed to inform nutrient-related management decisions, especially in streams and rivers. Nutrient stressor-response relationships are complicated by multiple interacting environmental factors, complex and indirect causal pathways involving diverse biotic assemblages and food web compartments, legacy (historic) nutrient sources such as agricultural sediments, and the naturally high spatiotemporal variabilityof lotic ecosystems. Determining nutrient levels at which ecosystems are affected is a critical first step for identifying, managing, and restoring aquatic resources impaired by eutrophication and maintaining currently unimpaired resources. The systematic review outlined in this protocol will compile and synthesize literature on the response of chlorophyll a to nutrients in streams, providing a state-of-the-science body of evidence to assess nutrient impacts to one of the most widely-used measures of eutrophication. This review will address two questions: "What is the response of chlorophyll a to total nitrogen and total phosphorus concentrations in lotic ecosystems?" and "How are these relationships affected by other factors?" METHODS Searches for published and unpublished articles (peer-reviewed and non-peer-reviewed) will be conducted using bibliographic databases and search engines. Searches will be supplemented with bibliography searches and requests for material from the scientific and management community. Articles will be screened for relevance at the title/abstract and full text levels using pre-determined inclusion criteria; 10% (minimum 50, maximum 200) of screened papers will be examined by multiple reviewers to ensure consistent application of criteria. Study risk of bias will be evaluated using a questionnaire developed from existing frameworks and tailored to the specific study types this review will encounter. Results will be synthesized using meta-analysis of correlation coefficients, as well as narrative and tabular summaries, and will focus on the shape, direction, strength, and variability of available nutrient-chlorophyll relationships. Sensitivity analysis and meta-regression will be used to evaluate potential effects of study quality and modifying factors on nutrient-chlorophyll relationships.

中文翻译：

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叶绿素 a 对 Lotic 生态系统中总氮和总磷浓度的响应：系统评价方案。

背景技术由氮和磷污染导致的淡水生态系统富营养化是全球的主要压力源。尽管科学家和利益相关者认识到养分污染问题，但仍需要严格综合科学证据来为与养分相关的管理决策提供信息，特别是在溪流和河流中。营养压力源-反应关系因多种相互作用的环境因素、涉及不同生物组合和食物网区室的复杂和间接因果途径、农业沉积物等遗留（历史）营养来源以及流动生态系统的自然高时空变异性而变得复杂。确定生态系统受到影响的营养水平是识别、管理、恢复因富营养化而受损的水生资源，并维持目前未受损的资源。本议定书中概述的系统评价将汇编和综合有关叶绿素 a 对溪流中营养物质的反应的文献，提供最科学的证据来评估营养物质对最广泛使用的富营养化措施之一的影响. 这篇综述将解决两个问题：“叶绿素 a 对流动生态系统中总氮和总磷浓度的反应是什么？” 以及“这些关系如何受到其他因素的影响？” 方法 将使用书目数据库和搜索引擎对已发表和未发表的文章（同行评审和非同行评审）进行搜索。检索将辅以参考书目检索和来自科学和管理界的材料请求。文章将使用预先确定的纳入标准在标题/摘要和全文级别进行相关性筛选；10%（最少 50 篇，最多 200 篇）的筛选论文将由多名评审员审查，以确保标准的一致应用。研究偏倚风险将使用从现有框架开发并针对本次审查将遇到的特定研究类型量身定制的问卷进行评估。结果将使用相关系数的荟萃分析以及叙述和表格摘要进行综合，并将重点关注可用营养-叶绿素关系的形状、方向、强度和可变性。