Griffith University, Environmental Futures Research Institute (EFRI), Southern Ocean Persistent Organic Pollutants (SOPOPP), Brisbane, QLD 4111, Australia.
Griffith University, Australian Rivers Institute (ARI), Brisbane, QLD 4111, Australia.
Sci Rep. 2017 Jun 29;7(1):4366. doi: 10.1038/s41598-017-04698-2.
Bulk stable isotope analysis provides information regarding food web interactions, and has been applied to several cetacean species for the study of migration ecology. One limitation in bulk stable isotope analysis arises when a species, such as Southern hemisphere humpback whales, utilises geographically distinct food webs with differing isotopic baselines. Migrations to areas with different baselines can result in isotopic changes that mimic changes in feeding relations, leading to ambiguous food web interpretations. Here, we demonstrate the novel application of radiocarbon measurement for the resolution of such ambiguities. Radiocarbon was measured in baleen plates from humpback whales stranded in Australia between 2007 and 2013, and in skin samples collected in Australia and Antarctica from stranded and free-ranging animals. Radiocarbon measurements showed lower values for Southern Ocean feeding than for extra-Antarctic feeding in Australian waters. While the whales mostly relied on Antarctic-derived energy stores during their annual migration, there was some evidence of feeding within temperate zone waters in some individuals. This work, to our knowledge, provides the first definitive biochemical evidence for supplementary feeding by southern hemisphere humpback whales within temperate waters during migration. Further, the work contributes a powerful new tool (radiocarbon) for tracing source regions and geographical feeding.
批量稳定同位素分析提供了有关食物网相互作用的信息，并已应用于几种鲸目动物的迁徙生态学研究。当一个物种（如南半球的座头鲸）利用具有不同同位素基线的地理位置不同的食物网时，批量稳定同位素分析会受到限制。向基线不同的地区迁移会导致类似于摄食关系变化的同位素变化，从而导致食物网解释不明确。在这里，我们展示了放射性碳测量在解决此类不确定性方面的新应用。我们测量了 2007 年至 2013 年在澳大利亚搁浅的座头鲸的鲸须板和在澳大利亚和南极洲采集的搁浅和自由游动的座头鲸的皮肤样本中的放射性碳。放射性碳测量结果表明，在澳大利亚水域，南大洋摄食的放射性碳值低于南极以外摄食的放射性碳值。尽管这些鲸鱼在每年的迁徙过程中主要依赖于南极来源的能量储存，但在一些个体中，有一些在温带水域摄食的证据。据我们所知，这项工作首次提供了明确的生化证据，证明南半球座头鲸在迁徙过程中会在温带水域进行补充摄食。此外，这项工作还提供了一种强大的新工具（放射性碳），用于追踪来源区域和地理摄食。
