Department of Biological Sciences, Macquarie University, North Ryde, Sydney, NSW, 2113, Australia.
NSW Department of Primary Industries, National Marine Science Centre, PO Box 4321, Coffs Harbour, NSW, 2450, Australia.
Oecologia. 2022 Jan;198(1):111-124. doi: 10.1007/s00442-021-05075-7. Epub 2021 Nov 17.
Globally, marine animal distributions are shifting in response to a changing climate. These shifts are usually considered at the species level, but individuals are likely to differ in how they respond to the changing conditions. Here, we investigate how movement behaviour and, therefore, redistribution, would differ by sex and maturation class in a wide-ranging marine predator. We tracked 115 tiger sharks (Galeocerdo cuvier) from 2002 to 2020 and forecast class-specific distributions through to 2030, including environmental factors and predicted occurrence of potential prey. Generalised Linear and Additive Models revealed that water temperature change, particularly at higher latitudes, was the factor most associated with shark movements. Females dispersed southwards during periods of warming temperatures, and while juvenile females preferred a narrow thermal range between 22 and 23 °C, adult female and juvenile male presence was correlated with either lower (< 22 °C) or higher (> 23 °C) temperatures. During La Niña, sharks moved towards higher latitudes and used shallower isobaths. Inclusion of predicted distribution of their putative prey significantly improved projections of suitable habitats for all shark classes, compared to simpler models using temperature alone. Tiger shark range off the east coast of Australia is predicted to extend ~ 3.5° south towards the east coast of Tasmania, particularly for juvenile males. Our framework highlights the importance of combining long-term movement data with multi-factor habitat projections to identify heterogeneity within species when predicting consequences of climate change. Recognising intraspecific variability will improve conservation and management strategies and help anticipate broader ecosystem consequences of species redistribution due to ocean warming.
在全球范围内，海洋动物的分布正在因气候变化而发生变化。这些变化通常在物种层面上进行考虑，但个体对变化条件的反应可能有所不同。在这里，我们研究了在一种广泛分布的海洋捕食者中，性别和成熟度类别如何影响它们的运动行为和重新分布。我们从 2002 年到 2020 年追踪了 115 条虎鲨（Galeocerdo cuvier），并通过环境因素和预测的潜在猎物出现情况，预测了特定类别的分布情况，直至 2030 年。广义线性和加性模型表明，水温变化，特别是在高纬度地区，是与鲨鱼运动最相关的因素。当水温升高时，雌性鲨鱼会向南扩散，而幼年雌性更喜欢 22 到 23°C 之间的狭窄温度范围，成年雌性和幼年雄性的存在与较低（<22°C）或较高（>23°C）的温度相关。在拉尼娜现象期间，鲨鱼会向高纬度移动，并使用较浅的等深线。与仅使用温度的简单模型相比，包括其潜在猎物的预测分布，显著提高了所有鲨鱼类别的适宜栖息地预测。澳大利亚东海岸附近的虎鲨活动范围预计将向南扩展约 3.5°，到达塔斯马尼亚州东海岸，特别是对于幼年雄性鲨鱼。我们的框架强调了将长期运动数据与多因素生境预测相结合，以识别物种内异质性的重要性，从而预测气候变化的后果。认识到种内变异性将改善保护和管理策略，并有助于预测由于海洋变暖导致的物种重新分布对更广泛的生态系统的影响。
