Department of Biological Sciences, University of Manitoba, Winnipeg, Manitoba, R3T 2N2, Canada.
Fisheries and Oceans Canada, Winnipeg, Manitoba, R3T 2N6, Canada.
Rapid Commun Mass Spectrom. 2020 Mar 30;34(6):e8612. doi: 10.1002/rcm.8612.
Analysis of the stable isotope ratios of carbon and nitrogen (δ C and δ N values) is increasingly being used to gain insight into predator trophic ecology, which requires accurate diet-tissue discrimination factors (DTDFs), or the isotopic difference between prey and predator. Accurate DTDFs must be calculated from predators consuming an isotopically constant diet over time in controlled feeding experiments, but these studies have received little attention to date, especially among seabird species.
In this study, aquarium-housed Magellanic (Spheniscus magellanicus) and southern rockhopper (Eudyptes chrysocome) penguins were fed a single-prey source diet (capelin Mallotus villosus) for eight weeks. Stable isotope ratios (δ C and δ N values) of penguin blood (cellular component and plasma) and capelin were measured using mass spectrometry and then used to calculate DTDFs for both components of penguin blood by comparison with prey values.
The DTDFs for plasma were -0.63 ± 0.49 (mean ± SD) and -0.27 ± 0.22 for δ C values, and 2.60 ± 0.50 and 2.78 ± 0.22 for δ N values for Magellanic and southern rockhopper penguins, respectively, while the DTDFs for the cellular component were 1.22 ± 0.03 and 1.26 ± 0.03 for δ C values, and 2.54 ± 0.07 and 2.43 ± 0.17 for δ N values.
We compare our DTDFs with published values from blood components of penguins and discuss the effects that lipid extraction, sample storage, and diet have on the DTDFs of penguin blood components. This study provides accurate DTDFs of blood components for two seabird species of conservation concern, and is one of the first to provide plasma DTDFs for penguins, which are underrepresented in the seabird literature.
分析碳和氮的稳定同位素比值（δC 和 δN 值）越来越多地被用于深入了解捕食者的营养生态，这需要准确的饮食-组织分辨因子（DTDF），即猎物和捕食者之间的同位素差异。准确的 DTDF 必须通过在受控喂养实验中让捕食者长时间消耗同位素稳定的饮食来计算，但这些研究迄今为止受到的关注甚少，特别是在海鸟物种中。
在这项研究中，在水族馆中饲养的麦哲伦（Spheniscus magellanicus）和南部凤冠企鹅（Eudyptes chrysocome）被喂食单一猎物来源的饮食（毛鳞鱼 Mallotus villosus）八周。使用质谱法测量企鹅血液（细胞成分和血浆）和毛鳞鱼的稳定同位素比值（δC 和 δN 值），然后通过与猎物值比较来计算企鹅血液两个成分的 DTDF。
麦哲伦和南部凤冠企鹅的血浆 DTDF 分别为-0.63±0.49（平均值±标准差）和-0.27±0.22 对于 δC 值，以及 2.60±0.50 和 2.78±0.22 对于 δN 值，而细胞成分的 DTDF 分别为 1.22±0.03 和 1.26±0.03 对于 δC 值，以及 2.54±0.07 和 2.43±0.17 对于 δN 值。
我们将我们的 DTDF 与来自企鹅血液成分的已发表值进行比较，并讨论了脂质提取、样品储存和饮食对企鹅血液成分 DTDF 的影响。这项研究为两种受到保护关注的海鸟物种提供了准确的血液成分 DTDF，并且是首批为企鹅提供血浆 DTDF 的研究之一，企鹅在海鸟文献中代表性不足。
