Understanding change in Arctic marine ecosystems: polar bears as ecological indicators

预测环境变化对物种的影响需要了解繁殖、生存、生长、行为、栖息地利用、觅食、迁徙和生活史事件的时间。此外，早期预警指标对于有效的养护和管理至关重要。我研究的主要目的是找出与北极熊种群随时间变化相关的机制，以预测全球变暖的影响。这项研究使用了三种综合方法，包括卫星遥测(GPS项圈)、对记录生命历史或生理状态的组织进行分析，以及数学建模。加拿大北极正在对四个北极熊种群进行研究，这些种群反映了北极熊所经历的各种生态条件下不同的海冰状况和海冰变化率。我正在利用卫星遥测数据开发移动模型，将栖息地的动态和搜索策略结合起来，以确定具体的行为(例如，觅食、迁徙)。卫星遥测数据还被用来开发区域海冰模型，以预测未来与北极熊有关的情况，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，动态能源预算模型、人口预测模型)，可以更好地了解人口动态。对记录生命历史的组织(例如，牙齿环、爪子屑、激光消融牙齿中的同位素和头发中的激素)进行符合现场采样，以开发对北极熊生态的新的跨学科见解。利用这些组织档案，我将研究海冰状况的变化如何与北极熊的营养压力(例如毛皮质醇)相关联，同时将使用同位素签名来研究分布、饮食和迁徙模式。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。使用不同的生物标记物以及动物的已知历史和运动模式，我的研究将能够识别与冰川条件变化相关的模式。

Predicting the impacts of environmental change on species requires an understanding of reproduction, survival, growth, behaviour, habitat use, foraging, migration, and timing of life history events. Further, early warning indicators are essential for effective conservation and management. The main objective of my research is to identify the mechanisms associated with polar bear population change over time to predict the effects of global warming. The research uses three integrated approaches including satellite telemetry (GPS collars), analysis of tissues that record life history or physiological status, and mathematical modelling. Four polar bear populations are being studied in the Canadian Arctic that reflect different sea ice regimes and rates of sea ice change across the range of ecological conditions that polar bears experience. I am developing movement models using satellite telemetry data that integrate the dynamics of the habitat and searching strategies to identify specific behaviours (e.g., feeding, migration). Satellite telemetry data is also being 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) allows an improved understanding of population dynamics. Coincident field sampling of tissues that record life history (e.g., tooth annuli, claw shavings, isotopes in teeth by laser ablation, and hormones in hair) are being used to develop new cross-disciplinary insights into polar bear ecology. Using these tissue archives, I will examine how changes in sea ice regimes are associated with nutritional stress in polar bears (e.g., hair cortisol) while distribution, diet, and migration patterns will be examined using isotopic signature. 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. Using different biomarkers along with known histories and movement patterns of the animals, my research will be able to identify patterns associated with changing ice conditions.