NOAA Southwest Fisheries Science Center, Environmental Research Division, Monterey, CA, USA
Department of Ecology and Evolutionary Biology, University of California Santa Cruz, Santa Cruz, CA, USA.
Proc Biol Sci. 2018 Aug 22;285(1885):20181101. doi: 10.1098/rspb.2018.1101.
How animal movement decisions interact with the distribution of resources to shape individual performance is a key question in ecology. However, links between spatial and behavioural ecology and fitness consequences are poorly understood because the outcomes of individual resource selection decisions, such as energy intake, are rarely measured. In the open ocean, mesoscale features (approx. 10-100 km) such as fronts and eddies can aggregate prey and thereby drive the distribution of foraging vertebrates through bottom-up biophysical coupling. These productive features are known to attract predators, yet their role in facilitating energy transfer to top-level consumers is opaque. We investigated the use of mesoscale features by migrating northern elephant seals and quantified the corresponding energetic gains from the seals' foraging patterns at a daily resolution. Migrating elephant seals modified their diving behaviour and selected for mesoscale features when foraging. Daily energy gain increased significantly with increasing mesoscale activity, indicating that the physical environment can influence predator fitness at fine temporal scales. Results show that areas of high mesoscale activity not only attract top predators as foraging hotspots, but also lead to increased energy transfer across trophic levels. Our study provides evidence that the physical environment is an important factor in controlling energy flow to top predators by setting the stage for variation in resource availability. Such understanding is critical for assessing how changes in the environment and resource distribution will affect individual fitness and food web dynamics.
动物的运动决策如何与资源分布相互作用，从而塑造个体表现，这是生态学中的一个关键问题。然而，由于个体资源选择决策的结果（例如能量摄入）很少被测量，因此空间和行为生态学与适应度后果之间的联系还不甚了解。在开阔的海洋中，中尺度特征（约 10-100 公里），如锋面和漩涡，可以聚集猎物，从而通过自下而上的生物物理耦合来驱动觅食脊椎动物的分布。这些多产的特征众所周知会吸引捕食者，但它们在促进能量向顶级消费者转移方面的作用尚不清楚。我们研究了迁徙的北方象海豹对中尺度特征的利用，并以每日分辨率量化了海豹觅食模式所带来的相应能量增益。迁徙的象海豹改变了它们的潜水行为，并在觅食时选择了中尺度特征。每日能量增益随着中尺度活动的增加而显著增加，这表明物理环境可以在精细的时间尺度上影响捕食者的适应度。研究结果表明，高中尺度活动区域不仅作为觅食热点吸引顶级捕食者，而且还导致营养级之间的能量转移增加。我们的研究提供了证据，表明物理环境是通过为资源可用性的变化创造条件来控制能量流向顶级捕食者的一个重要因素。这种理解对于评估环境和资源分布的变化将如何影响个体适应度和食物网动态至关重要。
