Expansion of aquatic deoxygenation has altered the quality and availability of habitats and worsened body condition for many fish species through past decades. Identifying complementary chemical redox proxies in fish otoliths, in addition to Mn/Ca, would strengthen the ability to identify hypoxia exposure in a diversity of aquatic habitats. I/Ca ratios have been used in marine sediments and bio-mineralized materials for reconstruction of past redox conditions. In order to explore influences from various endogenous and exogenous processes, a large data set of I/Ca ratios from cores of otoliths, including fishes from fresh, estuarine, and coastal waters across 30 species within 10 taxonomic orders, were reported with other chemical proxies (Mn/Ca and Sr/Ca) using LA-ICP-MS. Our results suggest no single abiotic factor, including redox condition and salinity derived from Mn/Ca and Sr/Ca, predicts I/Ca values, while they may be correlated for specific fish species. Iodine may be related to organic matter in the cores of otoliths for some species. Maternal transfer, habitat change, dietary source, phylogeny, and ecology may also influence I/Ca ratios. Based on these exploratory results, we suggest a range of future research directions to further evaluate the factors controlling biomineralization of otolith iodine and its utility as a redox proxy.

在过去的几十年里，水生脱氧的扩大改变了栖息地的质量和可用性，并使许多鱼类的身体状况恶化。除 Mn/Ca 外，识别鱼耳石中的互补化学氧化还原代理将增强识别各种水生生境中缺氧暴露的能力。I/Ca 比率已用于海洋沉积物和生物矿化材料，以重建过去的氧化还原条件。为了探索各种内源性和外源性过程的影响，使用其他化学代理报告了来自耳石核心的大量 I/Ca 比数据集，包括来自 10 个分类目内 30 个物种的新鲜、河口和沿海水域的鱼类(Mn/Ca 和 Sr/Ca) 使用 LA-ICP-MS。我们的结果表明没有单一的非生物因素，包括来自 Mn/Ca 和 Sr/Ca 的氧化还原条件和盐度，预测 I/Ca 值，而它们可能与特定鱼类相关。对于某些物种，碘可能与耳石核心中的有机物有关。母体转移、栖息地变化、饮食来源、系统发育和生态学也可能影响 I/Ca 比率。基于这些探索性结果，我们提出了一系列未来的研究方向，以进一步评估控制耳石碘生物矿化的因素及其作为氧化还原代理的效用。