Positive interspecific interactions such as mutualism, commensalism, and facilitation are globally ubiquitous. Although research on positive interactions in terrestrial and marine systems has progressed over the past few decades, comparatively little is known about them in freshwater ecosystems. However, recent advances have brought the study of positive interactions in freshwater systems to a point where synthesis is warranted. In this review, we catalogue the variety of direct positive interactions described to date in freshwater ecosystems, discuss factors that could influence prevalence and impact of these interactions, and provide a framework for future research. In positive interactions, organisms exchange key resources such as nutrients, protection, transportation, or habitat to a net benefit for at least one participant. A few mutualistic relationships have received research attention to date, namely seed‐dispersing fishes, crayfishes and their ectosymbiotic cleaners, and communal‐spawning stream fishes. Similarly, only a handful of commensalisms have been studied, primarily phoretic relationships. Facilitation via ecosystem engineering has received more attention, for example habitat modification by beavers and bioturbation by salmon. It is well known that interaction outcomes vary with abiotic and biotic context. However, only a few of studies have examined context dependency in positive interactions in freshwater systems. Likewise, positive interactions incur costs as well as benefits; conceptualising interactions in terms of net cost/benefit to participants will help to clarify complex interactions. It is likely that there are many positive interactions that have yet to be discovered in freshwater systems. To identify these interactions, we encourage inductive natural history studies combined with hypotheses deduced from general ecological models. Research on positive interactions must move beyond small‐scale experiments and observational studies and adopt a cross‐scale approach. Likewise, we must progress from reducing systems to oversimplified pairwise interactions, toward studying positive interactions in broader community contexts. Positive interactions have been greatly overlooked in applied freshwater ecology, but have great potential for conservation, restoration, and aquaculture.

中文翻译：

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淡水中的积极生物相互作用：审查和研究指令

积极的种间相互作用，如共生、共生和促进，在全球范围内无处不在。尽管在过去几十年中对陆地和海洋系统中的积极相互作用的研究取得了进展，但在淡水生态系统中对它们的了解相对较少。然而，最近的进展已经将淡水系统中的积极相互作用的研究带到了需要综合的地步。在这篇综述中，我们对迄今为止在淡水生态系统中描述的各种直接的积极相互作用进行了编目，讨论了可能影响这些相互作用的普遍性和影响的因素，并为未来的研究提供了一个框架。在积极的互动中，生物体将关键资源（如营养、保护、运输或栖息地）交换为至少一个参与者的净收益。迄今为止，一些互惠关系受到了研究的关注，即散播种子的鱼类、小龙虾及其外共生清洁剂，以及共同产卵的溪流鱼类。同样，只研究了少数共生现象，主要是泳姿关系。通过生态系统工程的促进受到更多关注，例如海狸对栖息地的改变和鲑鱼的生物扰动。众所周知，相互作用的结果因非生物和生物环境而异。然而，只有少数研究检查了淡水系统中积极相互作用的背景依赖性。同样，积极的互动会带来成本和收益；根据参与者的净成本/收益来概念化互动将有助于澄清复杂的互动。在淡水系统中可能存在许多尚未发现的积极相互作用。为了识别这些相互作用，我们鼓励归纳自然历史研究与从一般生态模型推导出来的假设相结合。对积极相互作用的研究必须超越小规模实验和观察性研究，并采用跨规模的方法。同样，我们必须从减少系统到过度简化的成对交互，转向在更广泛的社区环境中研究积极的交互。在应用淡水生态学中，积极的相互作用被严重忽视，但在保护、恢复和水产养殖方面具有巨大潜力。我们鼓励归纳自然历史研究与从一般生态模型推导出的假设相结合。对积极相互作用的研究必须超越小规模实验和观察性研究，并采用跨规模的方法。同样，我们必须从减少系统到过度简化的成对交互，转向在更广泛的社区环境中研究积极的交互。在应用淡水生态学中，积极的相互作用被严重忽视，但在保护、恢复和水产养殖方面具有巨大潜力。我们鼓励归纳自然历史研究与从一般生态模型推导出的假设相结合。对积极相互作用的研究必须超越小规模实验和观察性研究，并采用跨规模的方法。同样，我们必须从减少系统到过度简化的成对交互，转向在更广泛的社区环境中研究积极的交互。在应用淡水生态学中，积极的相互作用被严重忽视，但在保护、恢复和水产养殖方面具有巨大潜力。研究更广泛的社区环境中的积极互动。在应用淡水生态学中，积极的相互作用被严重忽视，但在保护、恢复和水产养殖方面具有巨大潜力。研究更广泛的社区环境中的积极互动。在应用淡水生态学中，积极的相互作用被严重忽视，但在保护、恢复和水产养殖方面具有巨大潜力。