Ecology of polar bears in a changing climate

北极熊赖以生存的海冰栖息地很容易受到预计的气候变化的影响。海冰范围、持续时间、厚度和积雪的减少，以及边缘冰带的位移，不仅会显著影响北极熊的繁殖成功、觅食、迁徙模式和生存，还会影响它们的海洋哺乳动物猎物。这项研究的目的是确定影响决定北极熊数量变化的重要人口比率（出生、死亡、迁入和迁出）的潜在生态过程。它包括对北极熊生活史组成部分的调查，以及对它们的生活史与气候、海冰和猎物之间的联系进行定量描述。研究活动集中在3个种群（波弗特海、福克斯盆地和西哈德逊湾）。生境连通性、破碎化、运动走廊和生境斑块大小的景观生态学原理是理解气候变化相关影响的框架。重点放在成年雌性身上，以评估它们相对于空间利用模式的生殖成功率。长期目标是发展描述性指标和预测能力，以了解气候变率和变化在时空背景下对北极熊及其猎物的影响。该项目涉及4个核心领域的重大创新：1)结合卫星冰图像，通过卫星跟踪评估气候和海冰条件对北极熊运动时空格局的影响；2)海冰条件的年际变率和方向性变化对表型指标、生活史特征和种群动态的影响；3)利用环空宽度推断生活史事件，检查北极熊牙齿中牙骨质沉积。4)使用生理参数，如血清尿素/血清肌酐、瘦素和触珠蛋白水平来评估禁食/喂养动态和健康。该项目将产生北极熊与其环境之间关系的定量数据，这些数据可用于预测未来对气候变化的生态反应。

The sea ice habitat upon which polar bears depend is vulnerable to projected climate change. Reduction in sea ice extent, duration, thickness, and snow cover, as well as displacement of the marginal ice zone can significantly impact reproductive success, foraging, migration patterns, and survivorship not only of polar bears, but also of their marine mammal prey. The objective of this research is to identify the underlying ecological processes that affect vital population rates (births, deaths, immigration and emigration) that determine changes in polar bear abundance. It involves the investigation of life history components of polar bears and the development of quantitative descriptions of the linkages between their life history and climate, sea ice, and prey. Research activities are focussed in 3 populations (Beaufort Sea, Foxe Basin, and Western Hudson Bay). Landscape ecology principles of habitat connectivity, fragmentation, movement corridors, and habitat patch size are the proposed framework for understanding climate change related impacts. Focus is placed on adult females to assess their reproductive success relative to space-use patterns. The long-term goal is the development of descriptive metrics and predictive capacity for understanding the impacts of climate variability and change on polar bears and their prey in a spatial-temporal context. The project involves significant innovation in 4 core areas: 1) Assessing the effects of climate and sea ice conditions on spatial and temporal patterns of polar bears movements via satellite tracking in conjunction with satellite ice imagery, 2) The effects of interannual variability and directional change in sea ice conditions on the phenotypic metrics, life history traits, and population dynamics, 3) Examination of cementum deposition in teeth collected from polar bears with inferences on life history events derived from annuli widths, 4) Use of physiological parameters such as serum urea/serum creatinine, leptin, and haptoglobin levels to assess fasting/feeding dynamics and health. The project will yield quantitative data on the relationship between polar bears and their environment that can be used to predict future ecological responses to climate change.