Climate change consequences for an Arctic apex predator: polar bears as ecological indicators

预测环境变化对物种的影响需要了解生物过程，如繁殖、生存、生长、行为、栖息地利用、觅食、迁徙和生活史事件的时间安排。这个项目的主要目标是通过记录过去的动态来确定与北极熊(Ursus Maritimus)种群随时间变化有关的机制，以便能够预测未来相对于气候变化和海冰条件变化的变化。北极熊是北极海洋生态系统的顶级捕食者，制定预警指标对有效养护和管理至关重要。这项研究使用了三种综合方法，包括卫星遥测、对记录生命历史或生理状态的组织的分析，以及数学建模。该项目建立在对西哈德逊湾和波弗特海北极熊种群的长期研究基础上。该项目侧重于四个主题：1)利用遥感评估与关键生活史参数有关的时间方面的北极熊的空间生态和栖息地利用；2)开发从组织微观分析评估生活史事件的跨学科方法；3)探索生态系统动力学和能量学模型以预测北极熊的未来状况；4)研究北极熊作为北极海洋生态系统中的关键捕食者的作用。卫星遥测数据将被用来开发区域海冰模型，以预测未来与北极熊相关的条件，重点是影响繁殖和生存的关键时期。将这些数据整合到数学模型中(例如，动态能量预算模型、人口预测模型和生态系统模型)，可以更好地理解人口动态。对记录生命历史的组织(如牙环、爪屑、毛发、脂肪和血液)的现场采样正在被用来发展对北极熊生态的新的跨学科见解。组织档案将用于研究海冰状况的变化如何与北极熊的营养压力相关(例如，毛发中的皮质醇水平)，而分布、饮食和迁徙模式将使用同位素特征和脂肪酸图谱进行研究。这些结果将具体解决气候变化如何影响北极熊的觅食成功和活动模式，从而可能提供对北极熊身体状况与人口统计相关的下降的机械理解。目标是利用这些档案来收集有关应激源反应的新的重要信息，以开发早期预警指标。总体而言，该项目将有助于采用与投影模型相结合的遥感方法，采用新的跨学科技术。

Predicting the impacts of environmental change on species requires an understanding of biological processes such as reproduction, survival, growth, behaviour, habitat use, foraging, migration, and timing of life history events. The main objective of this project is to identify the mechanisms associated with polar bear (Ursus maritimus) population change over time by documenting past dynamics to allow predictions of future change relative to climate change and altered sea ice conditions. Polar bears are the apex predator in the Arctic marine ecosystem and development of early warning indicators are essential for effective conservation and management. The research uses three integrated methodologies including satellite telemetry, analysis of tissues that record life history or physiological status, and mathematical modelling. The project builds on long-term polar bear population studies in Western Hudson Bay and the Beaufort Sea. This project focuses on four themes: 1) the spatial ecology and habitat use of polar bears using remote sensing to assess temporal aspects relevant to key life history parameters, 2) development of interdisciplinary means of assessing life history events from microanalysis of tissues, 3) exploration of ecosystem dynamics and energetics modelling to predict the future status of polar bears, and 4) examine the role of polar bears as a keystone predator in Arctic marine ecosystems. Satellite telemetry data will be used to develop regional sea ice models to predict future conditions relevant to polar bears with focus on key periods that affect reproduction and survival. Integration of these data into mathematical models (e.g., dynamic energy budget models, population projection models, and ecosystem models) allows an improved understanding of population dynamics. Coincident field sampling of tissues that record life history (e.g., tooth annuli, claw shavings, hair, fat, and blood) are being used to develop new cross-disciplinary insights into polar bear ecology. Tissue archives will be used to examine how changes in sea ice regimes are associated with nutritional stress in polar bears (e.g., cortisol levels in hair) while distribution, diet, and migration patterns will be examined using isotopic signatures and fatty acid profiles. The results will specifically address how climate change affects foraging success and movement patterns of polar bears, and thus may provide a mechanistic understanding of the decline in polar bear body condition associated with demographics. The goal is to use these archives to glean new and important information about stressor responses over time to develop early warning indicators. Overall, this project will serve to introduce novel interdisciplinary techniques with remote sensing approaches integrated with projection models.