1. Biogeochemical ecology of organisms typically focuses on C, N, and P despite c. 25 elements needed for organismal function. Embracing novel suites of elements in biomass is a first step in linking elements to organismal and ecological functions, improving our ability to predict how species interact with their environment. This research area has been fruitful for terrestrial plant ecologists, yet few studies have considered animal ecology within a framework encompassing elements beyond C, N, and P.
2. Freshwater mussels (Unionidae) are highly endangered filter-feeding bivalves that can be important to ecosystem function. Interspecific trait variation influences soft tissue elemental composition that has been linked to ecosystem biogeochemical cycling using traditional C:N:P stoichiometric approaches. However, whether interspecific trait variation influences shell elemental composition is not well studied, especially for elements other than C, N, and P.
3. We quantified B, C, Ca, Cu, Fe, K, Mg, Mn, N, P, and Zn and constructed isometric log-ratios (nutrient balances) for shells of seven species comprising diverse morphologies and two life history strategies to test whether shell elemental composition is influenced by these biological traits. Additionally, we evaluated whether the growth rate hypothesis applies to shell P concentration and elements associated with P in nutrient balances.
4. Bulk and trace elemental composition varied taxonomically and with biological traits. Nutrient balances for [C | P] and [C, Ca | P] were influenced by life history strategy. Shell P composition was negatively related to growth rates. Coincidentally, [C | P] and [C, Ca | P] were greater in the species with the highest growth rate (Lampsilis ornata), suggesting greater concentrations of C and Ca relative to P in shells of faster growing mussels. We hypothesise this observed pattern results from greater P allocation to soft tissue in fast growing mussels compared to slow growing mussels studied previously, but explicit tests of this hypothesis in a strict stoichiometric framework are needed.
5. Overall, we demonstrate how quantifying elements beyond C, N, and P, may be useful in uncovering elemental diversity associated with trade-offs in elemental allocation among biological traits. Whether such elemental diversity correlates to evolutionary history or contributes to the biogeochemical template of freshwater habitats remains to be seen but should be explored.

中文翻译：

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淡水贻贝壳（贻贝科）中元素之间的关联及其与形态和生活史的关系

1. 生物的生物地球化学生态学通常集中于C，N，和P尽管Ç。有机体功能所需的 25 种元素。在生物质中采用新的元素套件是将元素与有机体和生态功能联系起来的第一步，从而提高我们预测物种如何与其环境相互作用的能力。这一研究领域对陆生植物生态学家来说卓有成效，但很少有研究在包含 C、N 和 P 之外的元素的框架内考虑动物生态学。
2. 淡水贻贝（贻贝科）是高度濒危的滤食性双壳类动物，对生态系统功能很重要。种间性状变异影响软组织元素组成，而软组织元素组成与使用传统 C:N:P 化学计量方法的生态系统生物地球化学循环有关。然而，种间性状变异是否影响壳元素组成尚未得到很好的研究，尤其是对于 C、N 和 P 以外的元素。
3. 我们量化了 B、C、Ca、Cu、Fe、K、Mg、Mn、N、P 和 Zn，并构建了包括不同形态和两种生活史策略的七种贝壳的等距对数比（营养平衡），以测试是否壳元素组成受这些生物学特性的影响。此外，我们评估了增长率假设是否适用于壳磷浓度和养分平衡中与磷相关的元素。
4. 散装和微量元素组成在分类学上和生物学特征上各不相同。[C | 的营养平衡] P] 和 [C, Ca | P] 受生活史策略的影响。壳牌 P 成分与增长率呈负相关。巧合的是，[C | P] 和 [C, Ca | P] 在生长速度最高的物种 ( Lampsilis ornata ) 中更大，这表明生长速度更快的贻贝壳中的 C 和 Ca 浓度高于 P。我们假设这种观察到的模式是由于与先前研究的缓慢生长的贻贝相比，快速生长的贻贝中软组织的磷分配更多，但需要在严格的化学计量框架中对这一假设进行明确的测试。
5. 总体而言，我们展示了量化 C、N 和 P 之外的元素如何有助于揭示与生物性状之间元素分配权衡相关的元素多样性。这种元素多样性是否与进化历史相关或有助于淡水栖息地的生物地球化学模板仍有待观察，但应该探索。