Andrzejaczek Samantha, Gleiss Adrian C, Lear Karissa O, Pattiaratchi Charitha, Chapple Taylor K, Meekan Mark G
Oceans Graduate School and The UWA Oceans Institute, The University of Western Australia, Crawley, Western Australia 6009, Australia.
The Australian Institute of Marine Science, Crawley, Western Australia 6009, Australia.
R Soc Open Sci. 2020 Aug 19;7(8):200789. doi: 10.1098/rsos.200789. eCollection 2020 Aug.
Tiger sharks, , are a keystone, top-order predator that are assumed to engage in cost-efficient movement and foraging patterns. To investigate the extent to which oscillatory diving by tiger sharks conform to these patterns, we used a biologging approach to model their cost of transport. High-resolution biologging tags with tri-axial sensors were deployed on 21 tiger sharks at Ningaloo Reef for durations of 5-48 h. Using overall dynamic body acceleration as a proxy for energy expenditure, we modelled the cost of transport of oscillatory movements of varying geometries in both horizontal and vertical planes for tiger sharks. The cost of horizontal transport was minimized by descending at the smallest possible angle and ascending at an angle of 5-14°, meaning that vertical oscillations conserved energy compared to swimming at a level depth. The reduction of vertical travel costs occurred at steeper angles. The absolute dive angles of tiger sharks increased between inshore and offshore zones, presumably to reduce the cost of transport while continuously hunting for prey in both benthic and surface habitats. Oscillatory movements of tiger sharks conform to strategies of cost-efficient foraging, and shallow inshore habitats appear to be an important habitat for both hunting prey and conserving energy while travelling.
虎鲨是一种关键的顶级掠食者，被认为具有高效的移动和觅食模式。为了研究虎鲨的振荡式潜水在多大程度上符合这些模式，我们采用了生物记录方法来模拟它们的运输成本。在宁格鲁珊瑚礁，我们将带有三轴传感器的高分辨率生物记录标签部署在21只虎鲨身上，时长为5至48小时。我们以总体动态身体加速度作为能量消耗的替代指标，模拟了虎鲨在水平和垂直平面上不同几何形状的振荡运动的运输成本。水平运输成本通过以尽可能小的角度下降并以5至14度的角度上升来最小化，这意味着与在水平深度游泳相比，垂直振荡节省了能量。垂直行程成本的降低发生在更陡的角度。虎鲨在近岸和离岸区域之间的绝对潜水角度增加，大概是为了在底栖和表层栖息地持续捕食时降低运输成本。虎鲨的振荡运动符合高效觅食策略，浅海近岸栖息地似乎是捕食猎物和在游动时节省能量的重要栖息地。
