1. Native freshwater mussels are a guild of benthic, filter feeding invertebrates that perform important ecological functions in rivers. Because of their long lifespans (30–50 years or longer), mussels are slow to respond to human‐induced alterations. Thus, development of sensitive indicators of mussel population responses to river conditions and management would be beneficial. Compared to marine species, estimation of vital rates (e.g. survival, growth) in freshwater mussels has received little attention.
2. We placed passively integrated transponder tags on 578 mussels of four species (Amblema plicata, Cyclonaias pustulosa, Obliquaria reflexa, and Pleurobema sintoxia) in a well‐studied mussel assemblage in a side channel of the upper Mississippi River. Growth and survival of tagged mussels were assessed annually for 4 years across core (high density) and peripheral (low density) areas of the assemblage.
3. Overall survival was highly variable, ranging from c. 15 to 90%, and was related to life history, habitat quality, and hydrologic events. Survival, which varied significantly among species and over time, was consistently higher in the dense and species‐rich core of the mussel assemblage, relative to the periphery because substrates were consistently more stable in the core of the mussel bed relative to the periphery. Substrate movement during low flows was an order of magnitude lower in the core relative to the periphery, and survival was inversely related to stability of river substrates. Patterns in habitat‐specific survival indicate source–sink population dynamics such that mussels in the core habitat provide recruitment to the periphery, but mussels in the periphery are subject to unsustainably low survival; additional studies to track the source of recruitment in the periphery are needed to test this hypothesis.
4. Growth rate did not vary significantly between core and peripheral areas but did vary by species. Growth rate (proportional change per year) declined with age, and was similar at mean age for A. plicata (0.016 per year), P. sintoxia (0.015 per year), and C. pustulosa (0.013 per year), but much lower for O. reflexa (0.008 per year).
5. Effective management decisions for mussels requires a better understanding of how vital rates govern populations and how they vary across a suite of physical and biological factors. Information on how population vital rates vary among species and over time gives managers another tool to understand how mussels may respond to management actions such as habitat restoration projects. Given the importance of substrate stability inferred from this study, management actions that maintain or increase substrate stability are likely to result in high quality mussel assemblages and may restore a valuable component of ecosystem function in this region.

中文翻译：

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估计人口密度，以评估密西西比河上游贻贝种群的相对健康状况

1. 本地淡水贻贝是底栖动物，过滤器捕食的无脊椎动物行会，在河流中起着重要的生态功能。由于贻贝寿命长（30–50年或更长时间），贻贝对人为改变的反应较慢。因此，开发贻贝种群对河流状况和管理的敏感指标将是有益的。与海洋物种相比，淡水贻贝的生命率（例如生存率，生长率）的估算几乎没有受到关注。
2. 我们在密西西比河上游侧通道的贻贝组合中，对4种物种（安布莲，Cyclonaias pustulosa，Obliquaria reflexa和Pleurobema sintoxia）的578个贻贝进行了被动集成的应答器标签。在组合的核心（高密度）和外围（低密度）区域，每年评估标记贻贝的生长和存活情况，为期4年。
3. 总生存期变化很大，从Ç。15％至90％，与生活史，栖息地质量和水文事件有关。生存在物种之间随时间变化很大，并且在贻贝集合体的密集且物种丰富的核心相对于外围始终较高，这是因为基质在贻贝床的核心相对于外围始终更稳定。在低流量条件下，底物的运动在岩心中相对于外围要低一个数量级，而存活率与河流底物的稳定性成反比。特定栖息地的生存模式表明了源汇库的种群动态，例如核心栖息地的贻贝向外围提供了补充，但是外围的贻贝则承受不可持续的低生存率。
4. 核心区域和外围区域之间的增长率没有明显变化，但随物种的不同而变化。增长率（每年成比例的变化）随着年龄的增长而下降，在A. plicata（每年0.016），P。sintoxia（每年0.015）和P. pustulosa（每年0.013）时，平均年龄相近，但要低得多为O. reflexa（0.008每年）。
5. 有效的贻贝管理决策需要更好地了解生命率如何控制种群以及它们在一系列物理和生物学因素之间的变化。有关种群生命率如何在物种之间变化以及随着时间推移而变化的信息，为管理人员提供了另一种工具，以了解贻贝如何应对诸如栖息地恢复项目之类的管理行动。鉴于从这项研究推断出的底物稳定性的重要性，维持或增加底物稳定性的管理措施可能导致高质量的贻贝组合，并可能恢复该地区生态系统功能的重要组成部分。