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首页> 外文期刊>PLoS One >Vertical Movement Patterns and Ontogenetic Niche Expansion in the Tiger Shark, Galeocerdo cuvier
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Vertical Movement Patterns and Ontogenetic Niche Expansion in the Tiger Shark, Galeocerdo cuvier

机译：虎鲨的垂直运动模式和个体发育的生态位扩展

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Sharks are top predators in many marine ecosystems and can impact community dynamics, yet many shark populations are undergoing severe declines primarily due to overfishing. Obtaining species-specific knowledge on shark spatial ecology is important to implement adequate management strategies for the effective conservation of these taxa. This is particularly relevant concerning highly-mobile species that use wide home ranges comprising coastal and oceanic habitats, such as tiger sharks, Galeocerdo cuvier. We deployed satellite tags in 20 juvenile tiger sharks off northeastern Brazil to assess the effect of intrinsic and extrinsic factors on depth and temperature usage. Sharks were tracked for a total of 1184 d and used waters up to 1112 m in depth. The minimum temperature recorded equaled 4°C. All sharks had a clear preference for surface ( 5 m) waters but variability in depth usage was observed as some sharks used mostly shallow ( 60 m) waters whereas others made frequent incursions into greater depths. A diel behavioral shift was detected, with sharks spending considerably more time in surface ( 10 m) waters during the night. Moreover, a clear ontogenetic expansion in the vertical range of tiger shark habitat was observed, with generalized linear models estimating a ~4-fold increase in maximum diving depth from 150- to 300-cm size-classes. The time spent in the upper 5 m of the water column did not vary ontogenetically but shark size was the most important factor explaining the utilization of deeper water layers. Young-of-the-year tiger sharks seem to associate with shallow, neritic habitats but they progressively move into deeper oceanic habitats as they grow larger. Such an early plasticity in habitat use could endow tiger sharks with access to previously unavailable prey, thus contributing to a wider ecological niche.
机译：鲨鱼是许多海洋生态系统中的主要掠食者，并且可以影响社区动态，但是许多鲨鱼种群正主要由于过度捕捞而急剧下降。获得有关鲨鱼空间生态的物种特定知识对于实施有效管理这些生物分类群的适当管理策略很重要。对于使用范围广泛的高活动性物种，包括沿海鲨鱼和海洋生境，如虎鲨，加利奥多（Galeeocerdo cuvier），这尤其适用。我们在巴西东北部的20个少年虎鲨中部署了卫星标签，以评估内部和外部因素对深度和温度使用的影响。鲨鱼被追踪了总共1184 d，使用的水深达1112 m。记录的最低温度等于4°C。所有鲨鱼都对地表水（<5 m）有明显的偏爱，但在深度使用上存在差异，因为一些鲨鱼大多使用浅水（<60 m），而其他鲨鱼则经常侵入较大深度。鲨鱼的行为发生了变化，夜间鲨鱼在地表水（<10 m）中花费了更多的时间。此外，在虎鲨栖息地的垂直范围内观察到明显的个体发育，广义线性模型估计最大潜水深度从150厘米增加到300厘米，增加了约4倍。水柱上部5 m所花费的时间在个体发育上没有变化，但鲨鱼的大小是解释利用深水层的最重要因素。年少的虎鲨似乎与浅色，浅色的栖息地有关，但是随着它们的长大，它们逐渐移入更深的海洋栖息地。在栖息地使用中如此早期的可塑性可以使虎鲨获得以前无法获得的猎物，从而有助于扩大生态位。

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