There is growing evidence of the potential negative consequences of altered flow regimes, in terms of magnitude, frequency, timing, duration or season pattern, on fluvial ecosystems and the fisheries they support. The scientific and policy communities have acknowledged the need for a better understanding of the effects of flow alteration on fish productivity. We conducted a systematic map to provide an overview of the existing literature base on the effects of flow-regime changes on direct outcomes of freshwater or estuarine fish productivity in temperate regions to inform stakeholders and policy makers. To identify relevant articles for inclusion in this systematic map, we searched six bibliographic databases, 29 organizational websites, one search engine, and 297 reviews, and solicited grey literature through relevant sources. We screened articles at title and abstract, then by full-text using predefined inclusion criteria. Included studies were coded for key variables of interest, along with a very basic critical appraisal for internal validity (i.e., susceptibility to bias). The quantity and characteristics of the available evidence, knowledge gaps and subtopics with sufficient coverage for full systematic reviewing are reported in a narrative synthesis. The distribution and frequency of examined effects of flow-regime changes on fish productivity outcomes are presented in visual heatmaps. A total of 1368 studies from 1199 articles were included in the systematic map database and used to identify a number of interesting themes in the evidence base: (1) large evidence bases were found in temperate regions of United States of America (USA), Canada, and Australia; (2) most studies either used a temporal or spatial trend design i.e., lacking a ‘true’ before intervention time period, or no intervention control sites; (3) the most studied causes of altered flow regime were natural (e.g., floods, droughts, climate change), hydroelectric facilities (hydro), and dams with no hydro; and (4) there were clear clusters of studies evaluating effects of changes in magnitude and surrogate measures (e.g., velocity, water depth) on fish productivity outcomes, in particular abundance and diversity metrics. A number of potential knowledge gaps were identified: including geographic (Northern Africa, and possibly parts of Asia), causes of altered flow regime (restoration, land-use change, and water abstraction/extraction/diversion), interventions (flow duration, frequency, rate of change, or timing), outcomes (population viability) and specific intervention/cause/outcome groups (e.g., changes in flow magnitude due to hydro or natural causes and fish survival, performance, and reproduction). A few aspects in methodology were also identified across studies, primarily a lack of true comparators (e.g., temporal or spatial trend designs). This map suggests subtopics warranting future evidence synthesis include, examinations into how changes in flow magnitude affects: (1) fish abundance for dams with no hydro causes; (2) fish abundance, diversity/richness, migration, and growth for hydro causes; and (3) fish abundance, diversity/richness, growth, community structure, recruitment, and migrating fish abundance for natural causes. More comprehensive evidence is needed to understand how: (1) fish productivity metrics are affected by changes in flow regime due to restoration, land-use change, and water withdrawal/diversion activities; (2) how fish productivity is affected by changes to components of flow regime other than magnitude (e.g., flow duration, frequency); and (3) changes in flow magnitude due to hydro or natural causes affect fish survival, performance, and reproduction; and (4) changes in flow regime (all causes, all interventions) affect population viability.

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在温带地区，水流变化对鱼类生产力有什么影响？系统地图

越来越多的证据表明，在规模，频率，时间，持续时间或季节模式方面，流动方式改变对河流生态系统及其所支持的渔业可能产生负面影响。科学和政策界已经认识到需要更好地了解流量变化对鱼类生产力的影响。我们进行了系统的地图绘制，以了解现有文献的概述，以了解流量变化对温带地区淡水或河口鱼类生产力的直接结果的影响，以告知利益相关者和决策者。为了确定要包含在该系统地图中的相关文章，我们搜索了六个书目数据库，29个组织网站，一个搜索引擎和297条评论，并通过相关来源征集了灰色文献。我们按照标题和摘要对文章进行了筛选，然后使用预定义的纳入标准对文章进行了全文筛选。纳入研究被编码为关注的关键变量，以及对内部有效性（即偏见的敏感性）的非常基本的批判性评估。叙事综合报告中报道了现有证据的数量和特征，知识差距和足够全面进行系统审查的子主题。视觉热图显示了水流变化对鱼类生产力结果的影响的分布和频率。系统地图数据库中包括来自1199篇文章的总共1368项研究，用于识别证据基础中的许多有趣主题：（1）在美国（加拿大）的温带地区发现了大的证据基础和澳大利亚；（2）大多数研究要么采用时间或空间趋势设计，即在干预时间之前缺乏“真实”，要么没有干预控制点。（3）对流态变化的研究最多的原因是自然的（例如洪水，干旱，气候变化），水力发电设施（水电）和无水坝。（4）有清晰的研究集群，评估幅度变化和替代指标（例如速度，水深）对鱼类生产力结果（特别是丰度和多样性指标）的影响。确定了许多潜在的知识鸿沟：包括地理区域（北非，以及亚洲的部分地区），水流状况变化的原因（恢复，土地利用变化和取水/提取/引水），干预措施（水流持续时间，频率） ，变更率或时间），结果（种群生存力）和特定的干预/原因/结果组（例如，由于水源或自然原因以及鱼类的生存，繁殖和繁殖所引起的流量变化）。在研究中还确定了方法论的几个方面，主要是缺少真正的比较器（例如，时间或空间趋势设计）。该图建议需要综合未来证据的子主题包括，检查流量大小的变化如何影响：（1）没有水源的大坝鱼的丰度；（2）由于水源原因的鱼类丰度，多样性/丰富性，迁移和生长；（3）鱼的丰富度，多样性/丰富度，生长，社区结构，招募和迁移鱼的丰富度是自然原因。需要更全面的证据来了解如何：（1）鱼类生产力指标受恢复，土地用途变化以及取水/引水活动引起的水流变化的影响；（2）除了大小（例如，持续时间，频率）以外，水流状态的变化对鱼类生产力的影响如何；（3）由于水或自然原因引起的流量变化影响鱼类的生存，繁殖和繁殖；（4）流动方式的变化（所有原因，所有干预措施）都会影响种群的生存能力。