PDF(Pubmed)
Abstract：
BACKGROUND: Measuring coastal-pelagic prey fields at scales relevant to the movements of marine predators is challenging due to the dynamic and ephemeral nature of these environments. Whale sharks (Rhincodon typus) are thought to aggregate in nearshore tropical waters due to seasonally enhanced foraging opportunities. This implies that the three-dimensional movements of these animals may be associated with bio-physical properties that enhance prey availability. To date, few studies have tested this hypothesis.
METHODS: Here, we conducted ship-based acoustic surveys, net tows and water column profiling (salinity, temperature, chlorophyll fluorescence) to determine the volumetric density, distribution and community composition of mesozooplankton (predominantly euphausiids and copepods) and oceanographic properties of the water column in the vicinity of whale sharks that were tracked simultaneously using satellite-linked tags at Ningaloo Reef, Western Australia. Generalised linear mixed effect models were used to explore relationships between the 3-dimensional movement behaviours of tracked sharks and surrounding prey fields at a spatial scale of ~ 1 km.
RESULTS: We identified prey density as a significant driver of horizontal space use, with sharks occupying areas along the reef edge where densities were highest. These areas were characterised by complex bathymetry such as reef gutters and pinnacles. Temperature and salinity profiles revealed a well-mixed water column above the height of the bathymetry (top 40 m of the water column). Regions of stronger stratification were associated with reef gutters and pinnacles that concentrated prey near the seabed, and entrained productivity at local scales (~ 1 km). We found no quantitative relationship between the depth use of sharks and vertical distributions of horizontally averaged prey density. Whale sharks repeatedly dove to depths where spatially averaged prey concentration was highest but did not extend the time spent at these depth layers.
CONCLUSIONS: Our work reveals previously unrecognized complexity in interactions between whale sharks and their zooplankton prey.
METHODS: Here, we conducted ship-based acoustic surveys, net tows and water column profiling (salinity, temperature, chlorophyll fluorescence) to determine the volumetric density, distribution and community composition of mesozooplankton (predominantly euphausiids and copepods) and oceanographic properties of the water column in the vicinity of whale sharks that were tracked simultaneously using satellite-linked tags at Ningaloo Reef, Western Australia. Generalised linear mixed effect models were used to explore relationships between the 3-dimensional movement behaviours of tracked sharks and surrounding prey fields at a spatial scale of ~ 1 km.
RESULTS: We identified prey density as a significant driver of horizontal space use, with sharks occupying areas along the reef edge where densities were highest. These areas were characterised by complex bathymetry such as reef gutters and pinnacles. Temperature and salinity profiles revealed a well-mixed water column above the height of the bathymetry (top 40 m of the water column). Regions of stronger stratification were associated with reef gutters and pinnacles that concentrated prey near the seabed, and entrained productivity at local scales (~ 1 km). We found no quantitative relationship between the depth use of sharks and vertical distributions of horizontally averaged prey density. Whale sharks repeatedly dove to depths where spatially averaged prey concentration was highest but did not extend the time spent at these depth layers.
CONCLUSIONS: Our work reveals previously unrecognized complexity in interactions between whale sharks and their zooplankton prey.
摘要：
背景：由于这些环境的动态和短暂性质，在与海洋捕食者运动相关的尺度上测量沿海中上层猎物场具有挑战性。由于季节性增加的觅食机会，人们认为鲸鲨（Rhincodontypus）在近岸热带水域聚集。这意味着这些动物的三维运动可能与增强猎物可用性的生物物理性质有关。迄今为止,很少有研究验证了这一假设。
方法：这里，我们进行了船基声学测量，净丝束和水柱剖面(盐度，温度,叶绿素荧光)来确定体积密度，中浮游动物（主要是euphausiids和co足类）的分布和群落组成以及鲸鲨附近水柱的海洋学特性，同时在Ningaloo礁使用卫星链接标签进行跟踪，西澳大利亚。广义线性混合效应模型用于在〜1km的空间尺度上探索追踪鲨鱼的三维运动行为与周围猎物场之间的关系。
结果：我们确定猎物密度是水平空间使用的重要驱动因素，鲨鱼占据了珊瑚礁边缘密度最高的区域。这些区域的特征是复杂的测深法，例如礁石沟和石峰。温度和盐度曲线显示，在测深高度（水柱的顶部40m）上方有一个充分混合的水柱。分层较强的区域与将猎物集中在海床附近的礁石沟和石峰有关，并在局部尺度(约1公里)上夹带生产力。我们发现鲨鱼的深度使用与水平平均猎物密度的垂直分布之间没有定量关系。鲸鲨反复潜入空间平均猎物浓度最高的深度，但并未延长在这些深度层花费的时间。
结论：我们的工作揭示了鲸鲨与其浮游动物猎物之间相互作用的复杂性。
方法：这里，我们进行了船基声学测量，净丝束和水柱剖面(盐度，温度,叶绿素荧光)来确定体积密度，中浮游动物（主要是euphausiids和co足类）的分布和群落组成以及鲸鲨附近水柱的海洋学特性，同时在Ningaloo礁使用卫星链接标签进行跟踪，西澳大利亚。广义线性混合效应模型用于在〜1km的空间尺度上探索追踪鲨鱼的三维运动行为与周围猎物场之间的关系。
结果：我们确定猎物密度是水平空间使用的重要驱动因素，鲨鱼占据了珊瑚礁边缘密度最高的区域。这些区域的特征是复杂的测深法，例如礁石沟和石峰。温度和盐度曲线显示，在测深高度（水柱的顶部40m）上方有一个充分混合的水柱。分层较强的区域与将猎物集中在海床附近的礁石沟和石峰有关，并在局部尺度(约1公里)上夹带生产力。我们发现鲨鱼的深度使用与水平平均猎物密度的垂直分布之间没有定量关系。鲸鲨反复潜入空间平均猎物浓度最高的深度，但并未延长在这些深度层花费的时间。
结论：我们的工作揭示了鲸鲨与其浮游动物猎物之间相互作用的复杂性。
