1. To understand the ecological factors behind the decline of functionally important threatened species with complex life cycles, many different life‐cycle stages need to be investigated. The highly threatened unionoid freshwater mussels, with their complex life cycle, including a parasitic stage on host fish, often have a large influence on biodiversity and ecosystem functioning.
2. The overall aim of the present article is to summarize and discuss the impact of two articles published in Aquatic Conservation: Marine and Freshwater Ecosystems (AQC) on biotic interactions and adaptation of a threatened unionoid mussel (Margaritifera margaritifera) to its host fish (Salmo trutta).
3. The two AQC publications described research on the influence of population size and density of mussels and host fish, and host–parasite interactions between mussels and their host fish, on the recruitment of juvenile mussels.
4. The results from these publications filled gaps in knowledge and resulted in recommendations and incentives for conservation. The results and method development have been used in practical conservation work with threatened mussel species and have been implemented and cited in management handbooks. The outcome of the publications has been implemented in large conservation and restoration projects, and in several recent scientific publications.
5. Specifically, the results from one publication showed that ecological parameters such as mussel and host fish density and population size influenced recruitment of the threatened freshwater pearl mussel. The results from the second publication showed that understanding host–parasite interactions is important for comparing the suitability of host fish strains, and that host fish strains differ in their suitability for mussel infestations. In combination, the articles show that integrating ecological parameters of threatened mussels and their host fish with host–parasite interaction experiments can be an important influence on conservation recommendations, adaptive management and national management programmes for threatened species.

中文翻译：

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证明了研究对生物相互作用和濒临灭绝的贻贝贻贝（Margaritifera margaritifera）对其寄主鱼类（Salmo trutta）的适应的实际影响

1. 为了了解具有重要生命周期的功能重要的受威胁物种数量下降的背后的生态因素，需要研究许多不同的生命周期阶段。受威胁严重的非典型淡水贻贝，其生命周期复杂，包括寄主鱼的寄生阶段，经常对生物多样性和生态系统功能产生重大影响。
2. 本文的总体目的是总结和讨论在水生生物保护中发表的两篇文章：海洋和淡水生态系统（AQC）对生物相互作用和受威胁的union贻贝（Margaritifera margaritifera）适应其寄主鱼类（Salmo trutta）的影响）。
3. AQC的两个出版物描述了贻贝和寄主鱼的种群规模和密度以及贻贝与其寄主鱼之间寄主与寄生虫相互作用对少年贻贝募集的影响的研究。
4. 这些出版物的结果填补了知识空白，并提出了保护建议和激励措施。研究结果和方法开发已用于濒危贻贝物种的实际保护工作，并已在管理手册中得到实施和引用。这些出版物的成果已经在大型的保护和恢复项目以及一些近期的科学出版物中得到了实施。
5. 具体而言，一份出版物的结果表明，贻贝和寄主鱼类密度以及种群大小等生态参数影响着濒临灭绝的淡水珍珠贻贝的募集。第二份出版物的结果表明，了解寄主与寄生虫的相互作用对于比较寄主鱼品系的适宜性很重要，而且寄主鱼品系对贻贝侵染的适宜性也有所不同。结合起来，这些文章表明，将受威胁的贻贝及其寄主鱼类的生态参数与寄主－寄生虫相互作用实验相结合，可能对保护建议，适应性管理和受威胁物种的国家管理计划产生重要影响。