Data from: Assessing stable isotope dynamics of diapausing Calanus finmarchicus and C. hyperboreus during the overwintering period: a laboratory experiment

This study aimed at describing changes in the stable isotopic composition of late copepodite stage V (CV) subarctic marine copepods (Calanus finmarchicus and C. hyperboreus) during overwintering non-feeding periods. Diapausing stage CVs sampled in deep waters of the Lower St. Lawrence Estuary (Québec, Canada) in late-September 2009 were monitored for 4 months under controlled laboratory conditions. CVs and newly moulted adults were analyzed for δ13C and δ15N signatures as well as lipid, carbon and nitrogen content. Lipids were extracted in half of the samples to compare δ13C of individuals with and without lipids and to evaluate the accuracy of mass balance correction models for δ13C under lipid influence. Lipid content generally decreased with time for both species, which was reflected in an increase of δ13C values of CVs but a constant δ13C in newly moulted adults. Accordingly, lipid extraction resulted in an increase of δ13C in CVs and adults. The mean δ13C signature of lipid-extracted individuals remained constant through the time for CVs of both species and for C. finmarchicus adults. δ15N signatures of individuals increased after lipid extraction, but this did not result in a constant value over time, suggesting that several endogenous metabolic processes affected nitrogen isotopic content. The accuracy of the mass balance model differed between species and stages, suggesting that lipid extraction should always be performed prior to applying mathematical corrections.本研究旨在阐明亚北极海洋桡足类——飞马哲水蚤（Calanus finmarchicus）与北极大哲水蚤（Calanus hyperboreus）的第V期晚期桡足幼体（copepodite stage V，CV）在越冬非摄食阶段的稳定同位素组成变化。2009年9月末，研究人员于加拿大魁北克省圣劳伦斯河下游河口的深水水域采集了滞育期第V期幼体，并在可控实验室条件下开展了为期4个月的监测实验。随后对第V期幼体与新蜕皮成体的碳同位素比值（δ¹³C）、氮同位素比值（δ¹⁵N）特征，以及脂质、碳与氮含量进行了分析。研究人员对半数样本实施脂质提取操作，以此对比含脂质与去脂质个体的δ¹³C值，并评估脂质干扰下δ¹³C质量平衡校正模型（mass balance correction models）的拟合精度。结果显示，两个物种的脂质含量均随培养时间整体下降，该变化体现为第V期幼体的δ¹³C值升高，而新蜕皮成体的δ¹³C值维持恒定。与之对应，脂质提取会提升第V期幼体与成体的δ¹³C值。经脂质提取的个体的平均δ¹³C特征值，在两个物种的第V期幼体以及飞马哲水蚤成体中均未随时间发生显著变化。经脂质提取后，个体的δ¹⁵N特征值有所升高，但该数值并未随时间趋于稳定，提示多种内源代谢过程会对氮同位素组成产生影响。此外，质量平衡校正模型的精度因物种与发育阶段而异，这表明在应用数学校正方法前，应始终优先开展脂质提取操作。