Stable isotope analysis of Southern Ocean myctophids using faecal otoliths

The tables and figures in this dataset represent the development of a method to estimate the stable isotope values of myctophids when only otoliths from faecal samples of predators (or sedimentary samples) are available. Otoliths from wild myctophids were collected from faecal samples of fur seals at Marion Island in the Southern Ocean, and were cleaned using NaOCl (bleach) before obtaining the stable isotope values of the otoliths' organic component. The cleaning step required correction which was done by establishing a correction curve based on the amount of otolith material to be cleaned.The next step involved establishing an offset value between otoliths and muscle that could be applied to otolith stable isotope values to estimate muscle values in the absence of fresh fish samples (only faecal or sedimentary otoltihs available). The offsets were calculated by measuring paired otolith and muscle values of Antarctic fish, while ensuring control for lipid content in muscle. With the offsets applied to the cleaned and corrected Marion Island samples, the utility of the method is demontrated by comparisons with published counterparts, and used in the stable isotope dietary mixing models of Marion Island predators including various southern elephant seal classes and killer whales. Analyses were done using R software. Juvenile southern elepehant seal diet modelling was improved, first models for sub-adult, adult female and adult male seals are now available, and killer whale modelling remains unresolved.本数据集收录的表格与图件，展示了一种仅能获取捕食者粪便样本（或沉积样本）中的耳石（otoliths）时，用于估算灯笼鱼科鱼类（Myctophids）稳定同位素（stable isotope）比值的方法开发流程。研究人员从南大洋马里恩岛的海狗粪便样本中采集了野生灯笼鱼的耳石，使用次氯酸钠（NaOCl，漂白剂）对耳石进行清洗后，测定其有机组分的稳定同位素比值。该清洗步骤需进行校正，校正方法为基于待清洗耳石的质量建立校正曲线。后续步骤为建立耳石与肌肉组织间的偏移值，以便在仅能获取粪便或沉积耳石、无新鲜鱼类样本的前提下，通过耳石稳定同位素比值估算肌肉组织的同位素比值。偏移值通过测定南极鱼类的配对耳石与肌肉组织同位素比值计算得到，并在计算过程中控制肌肉组织的脂质含量。将上述偏移值应用于经清洗与校正后的马里恩岛样本后，本研究通过与已发表的同类研究结果对比，验证了该方法的实用性；同时将该方法应用于马里恩岛捕食者的稳定同位素饮食混合模型（dietary mixing models）分析，涵盖各类南象海豹种群以及虎鲸。所有分析均通过R软件完成。本次研究优化了幼年南象海豹的饮食模型，现已可构建亚成体、成年雌性与成年雄性南象海豹的饮食模型，但虎鲸的相关模型仍未得到有效解决。