过去一千年南极阿德雷岛企鹅栖息地变迁及其驱动因素

Penguins are typical marine life in the Antarctica, and are very sensitive to changes in the terrestrial and marine environments. In the current global warming context, the impact of climate change on the geographical distribution and habitat of penguins is a crucial ecological issue. Ardley Island is the largest nesting area of Gentoo penguins in the South Shetlands. Currently, penguins occupy the eastern part of this island; however, studies suggested that penguins occupied the west side since the mid Holocene. There is no reasonable explanation for this penguin movement from the west to the east. In this project we use ornithogenic sediments as well as the penguin residues as carriers, which are taken from the eastern half of the island. By applying multidisciplinary research that combine elements, stable isotopes, biogeochemistry, paleoclimate, and atmospheric science, we infer penguin occupation time and substantial demographic changes in the eastern part of the island. Furthermore, we synthesize the results from various studies on Ardley Island in the past 20 years, comprehensively and comparatively analyze the occupation history of penguins in the two side of the island, determine the abandoned time of penguin colonies in the west, and clarify the time, reasons and key driving factors of penguin movement from the west to the east. This study opens new avenues to determine the local and global characteristics of habitat choice by penguins, and provides an important scientific basis for assessing the possible impact of future climate change on penguins breeding habitats; it is also of reference value for the safety of Penguin Ecological Reserve.

企鹅是南极典型海洋生物，对陆地和海洋环境变化非常敏感。在当前全球变暖背景下，气候变化对企鹅地理分布及栖息地的影响是一个至关重要的生态问题。阿德雷岛是南设德兰群岛金图企鹅最大巢区，现代企鹅聚集在岛屿东部，而历史时期企鹅在西部广泛分布，对于该岛企鹅栖息地的变迁目前还没有合理解释。本项研究以阿德雷岛东部企鹅粪土沉积和企鹅残体为载体；应用元素、同位素、生物地球化学、古气候学和大气科学等多学科交叉的研究方法，恢复该岛东部企鹅登陆时间和种群数量变化。结合过去20年的研究成果，综合对比分析阿德雷岛东西部企鹅聚居历史，判定西部企鹅聚落废弃时间，揭示企鹅从岛屿西部向东部迁徙的时间、原因和气候驱动机制。本项目为理解企鹅在局地乃至全球空间尺度上对栖息地的选择机制提供一个新的路径，并为评估未来气候变化对企鹅种群盛衰和聚集地可能产生的影响提供重要科学依据，对于企鹅生态安全和生态保护区的规划也有重要参考价值。

本项目拟开展历史时期南极企鹅栖息地的变迁及其影响因素研究，在预研阶段利用前期已获得的南极半岛阿德雷岛企鹅粪土沉积柱，重建了该岛东部企鹅聚居历史；综合对比该岛东西两侧企鹅数量变化记录，发现距今1000年来企鹅栖息地由西向东迁移，受到南极环状模（SAM）正相位和西风增强的驱动。在项目设定的研究目标实施的基础上，进一步拓展相关研究内容，利用企鹅微蛋壳的SEM-EDS分析和TOC、P元素、氮同位素和甾醇等多种指标，对罗斯海斯科特海岸邓洛普岛企鹅粪土沉积层进行了准确判定；利用重新校正后的多个企鹅粪土剖面/粪/残体的年代值，准确获取了罗斯海恩克斯堡岛不同企鹅巢区的年代区间，为重建两地企鹅栖息地和种群数量变化提供基础；利用莫愁湖沉积柱硅藻组成的聚类分析推断了东南极拉斯曼丘陵海陆相转化以及相对海平面变化，为研究企鹅栖息地变迁和海平面变化的关系提供基础。本项目为理解企鹅在局地以及环南极空间尺度上对栖息地的选择机制提供了重要科学依据。