Biology Department, Woods Hole Oceanographic Institution, Woods Hole, MA, USA.
Institute of Marine Sciences, University of California, Santa Cruz, Santa Cruz, CA, USA.
Sci Adv. 2023 Oct 4;9(40):eadi8200. doi: 10.1126/sciadv.adi8200.
Large predators frequent the open ocean where subsurface light drives visually based trophic interactions. However, we lack knowledge on how predators achieve energy balance in the unproductive open ocean where prey biomass is minimal in well-lit surface waters but high in dim midwaters in the form of scattering layers. We use an interdisciplinary approach to assess how the bioenergetics of scattering layer forays by a model predator vary across biomes. We show that the mean metabolic cost rate of daytime deep foraging dives to scattering layers decreases as much as 26% from coastal to pelagic biomes. The more favorable energetics offshore are enabled by the addition of a shallow scattering layer that, if not present, would otherwise necessitate costlier dives to deeper layers. The unprecedented importance of this shallow scattering layer challenges assumptions that the globally ubiquitous primary deep scattering layer constitutes the only mesopelagic resource regularly targeted by apex predators.
大型掠食者经常出没于开阔海域，那里的次表层光线驱动着基于视觉的营养相互作用。然而，我们对于掠食者如何在生产力低下的开阔海域中保持能量平衡却知之甚少，在那里，猎物生物量在光照良好的水面上很少，但在昏暗的中层水域中以散射层的形式大量存在。我们采用跨学科的方法来评估模型掠食者对散射层的生物能量学的探索如何在生物群落之间变化。我们表明，从沿海到远洋生物群落，白天深海觅食潜水到散射层的平均代谢成本率下降了多达 26%。这种更有利的能量学是通过添加一个浅层散射层来实现的，如果没有这个浅层散射层，否则就需要更昂贵的潜水才能到达更深的层。这个前所未有的浅层散射层的重要性挑战了一个假设，即全球普遍存在的主要深海散射层构成了只有顶级掠食者定期瞄准的唯一中层资源。
