Department of Life Sciences, University of Coimbra, Mare-Marine and Environmental Sciences Centre, 3000-456, Coimbra, Portugal.
British Antarctic Survey, Natural Environment Research Council, High Cross, Madingley Road, Cambridge, CB3 0ET, UK.
Sci Rep. 2020 Sep 16;10(1):15215. doi: 10.1038/s41598-020-72103-6.
Long-term studies of pelagic nekton in the Southern Ocean and their responses to ongoing environmental change are rare. Using stable isotope ratios measured in squid beaks recovered from diet samples of wandering albatrosses Diomedea exulans, we assessed decadal variation (from 1976 to 2016) in the habitat (δC) and trophic level (δN) of five important Southern Ocean squid species in relation to indices of environmental conditions-Southern Oscillation Index (SOI) and Southern Annular Mode (SAM). Based on δC values, corrected for the Suess effect, habitat had changed over the last 50 years for Taonius sp. B (Voss), Gonatus antarcticus, Galiteuthis glacialis and Histioteuthis atlantica but not Moroteuthopsis longimana. By comparison, mean δN values were similar across decades for all five species, suggesting minimal changes in trophic levels. Both SAM and SOI have increased in strength and frequency over the study period but, of the five species, only in Taonius sp. B (Voss) did these indices correlate with, δC and δN values, indicating direct relationships between environmental conditions, habitat and trophic level. The five cephalopod species therefore changed their habitats with changing environmental conditions over the last 50 years but maintained similar trophic levels. Hence, cephalopods are likely to remain important prey for top predators in Southern Ocean food webs, despite ongoing climate change.
南大洋远洋浮游动物的长期研究及其对正在发生的环境变化的反应很少见。利用从漂泊信天翁（Diomedea exulans）的饮食样本中回收的鱿鱼喙中测量的稳定同位素比值，我们评估了五种重要的南大洋鱿鱼物种的栖息地（δC）和营养水平（δN）在过去十年中的变化（1976 年至 2016 年），与环境条件指数（南方涛动指数（SOI）和南方环状模式（SAM））有关。根据 δC 值，对苏斯效应进行了校正，在过去的 50 年中，Taonius sp. B（Voss）、Gonatus antarcticus、Galiteuthis glacialis 和 Histioteuthis atlantica 的栖息地发生了变化，但 Moroteuthopsis longimana 的栖息地没有发生变化。相比之下，所有五种物种的平均 δN 值在几十年内相似，表明营养水平变化不大。在研究期间，SAM 和 SOI 的强度和频率都有所增加，但在这五种物种中，只有 Taonius sp. B（Voss）的这些指数与 δC 和 δN 值相关，表明环境条件、栖息地和营养水平之间存在直接关系。因此，在过去的 50 年中，这五种头足类动物随着环境条件的变化改变了它们的栖息地，但保持了相似的营养水平。因此，尽管持续的气候变化，头足类动物仍可能是南大洋食物网中顶级捕食者的重要猎物。
