Carlisle Aaron B, Goldman Kenneth J, Litvin Steven Y, Madigan Daniel J, Bigman Jennifer S, Swithenbank Alan M, Kline Thomas C, Block Barbara A
Proc Biol Sci. 2015 Jan 22;282(1799):20141446. doi: 10.1098/rspb.2014.1446.
Ontogenetic changes in habitat are driven by shifting life-history requirements and play an important role in population dynamics. However, large portions of the life history of many pelagic species are still poorly understood or unknown. We used a novel combination of stable isotope analysis of vertebral annuli, Bayesian mixing models, isoscapes and electronic tag data to reconstruct ontogenetic patterns of habitat and resource use in a pelagic apex predator, the salmon shark (Lamna ditropis). Results identified the North Pacific Transition Zone as the major nursery area for salmon sharks and revealed an ontogenetic shift around the age of maturity from oceanic to increased use of neritic habitats. The nursery habitat may reflect trade-offs between prey availability, predation pressure and thermal constraints on juvenile endothermic sharks. The ontogenetic shift in habitat coincided with a reduction of isotopic niche, possibly reflecting specialization upon particular prey or habitats. Using tagging data to inform Bayesian isotopic mixing models revealed that adult sharks primarily use neritic habitats of Alaska yet receive a trophic subsidy from oceanic habitats. Integrating the multiple methods used here provides a powerful approach to retrospectively study the ecology and life history of migratory species throughout their ontogeny.
栖息地的个体发育变化是由不断变化的生活史需求驱动的,并且在种群动态中发挥着重要作用。然而,许多远洋物种生活史的大部分内容仍知之甚少或完全未知。我们使用了一种新颖的组合方法,即对脊椎骨年轮进行稳定同位素分析、贝叶斯混合模型、等距线图和电子标签数据,来重建远洋顶级捕食者鲑鲨(Lamna ditropis)的栖息地和资源利用的个体发育模式。结果确定北太平洋过渡区是鲑鲨的主要育幼区,并揭示了在成熟年龄左右从海洋栖息地到更多利用近岸栖息地的个体发育转变。育幼栖息地可能反映了幼体恒温鲨鱼在猎物可获得性、捕食压力和热限制之间的权衡。栖息地的个体发育转变与同位素生态位的缩小相吻合,这可能反映了对特定猎物或栖息地的特化。利用标签数据为贝叶斯同位素混合模型提供信息表明,成年鲨鱼主要利用阿拉斯加的近岸栖息地,但从海洋栖息地获得营养补贴。整合这里使用的多种方法提供了一种强大的方法,可用于回顾性研究洄游物种在其整个个体发育过程中的生态和生活史。