Abstract The knowledge gap on the early life-history of sea turtles during the “lost years” continues to hinder research and conservation of this critical life stage when mortality rates are the highest. An oceanic model was used in combination with a Lagrangian particle tracking framework to simulate and identify potential post-hatchling dispersal trajectories of loggerhead and leatherback turtles in the South Western Indian Ocean. The study aimed to investigate the effect of hatchling swimming behaviour on hatchling dispersal and survival probability. To our knowledge, this study provides the first estimate of neonate sea turtle dispersal in the SWIO, by combining a particle tracking model with in situ hatchling behavioural data. The model revealed that most virtual hatchlings are transported south-westward in the Agulhas Current with three distinct final locations after a year-long simulation (each zone comprising on average > 20% of the total amount of particles): the Agulhas Return, the SE Atlantic and the Southern Ocean zones. However, because loggerhead hatchlings are less strong swimmers compared to leatherbacks, they can be advected northward in the near-shore coastal current. Simulations revealed that initial active swimming (frenzy) as well as variability in oceanic conditions strongly influenced dispersal of virtual hatchlings. Furthermore, variability in oceanic conditions dispersed virtual hatchlings into different areas where threats, like fisheries bycatch, might also influence their survival. Lastly, the results of this study have potentially broad implications for climate change if turtles adapt by nesting earlier/later during the nesting season or further south which may influence hatchling locomotor performance and ultimately survival at early life stages.

中文翻译：

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游泳行为和海洋学对两个洋流系统交汇处海龟幼体扩散的影响

摘要 在“失落的岁月”中，海龟早期生活史的知识差距继续阻碍着这一死亡率最高的关键生命阶段的研究和保护。海洋模型与拉格朗日粒子跟踪框架结合使用，以模拟和识别西南印度洋红海龟和棱皮龟的潜在孵化后扩散轨迹。该研究旨在调查幼体游泳行为对幼体扩散和存活概率的影响。据我们所知，这项研究通过将粒子跟踪模型与原位孵化行为数据相结合，首次估计了 SWIO 中新生海龟的扩散情况。该模型显示，经过长达一年的模拟（每个区域平均占粒子总量的 20% 以上）后，大多数虚拟幼龟在 Agulhas Current 中向西南方向迁移，具有三个不同的最终位置：Agulhas Return、SE大西洋和南大洋地区。然而，由于蠵龟的游泳能力不如棱皮龟，因此它们可以在近岸沿海洋流中向北平流。模拟表明，最初的活跃游泳（狂潮）以及海洋条件的变化强烈影响了虚拟幼龟的扩散。此外，海洋条件的变化将虚拟幼鱼分散到不同的区域，在这些区域，渔业兼捕等威胁也可能影响它们的生存。最后，