企鹅的生物传输对东南极湖泊生态环境变化的影响

In our previous work, we have reconstructed the fluctuation of historical penguin population and its response to climate change. However, the present studies on the impact of penguins, which are widely distributed across Antarctica, on their habitat environment are still scarce. This proposed project will focus on the input of both nutrient components and heavy metals from penguin droppings in order to access the eco-environmental influence of penguin bio-transportation in East Antarctica. For the study purpose, typical lake sediments influenced by guano will be selected as our main study carriers. Biogeochemical indicators such as pigments and biomarker compounds in the sediments will be analyzed emphatically. Based on the study of modern sedimentary processes, we can identify the clear environmental implications of these indicators, and then decode the input ratio of different organic matter sources into lacustrine sediments, and finally quantitatively reconstruct community structure and population abundance of the phytoplankton growing in lakes since Middle-late Holocene. Based on these results, we can carry out comparative research on the evolutionary record of phytoplankton species in lakes and the historical change of penguin population reconstructed in our previous studies at the same time scale. In addition, the concentration change features of bulk and speciation of typical heavy metals in the sediment profiles will be integrated into our analysis in order to better study the impacts and responding mechanism of penguin bio-transportation on the eco-environmental changes of lakes and ponds in East Antarctica. The study results will help us to objectively assess the response process of the fragile Antarctic lake ecosystem to climate change and bio-transportation in the context of global change, and also may provide reference data which is important to work out measures for the protection of natural eco-environment in Antarctica.

我们前期工作恢复出了企鹅种群数量变化，但对于在南极大量分布的企鹅对栖息地环境的影响目前还很少关注。申请项目拟从企鹅粪带来的营养成分和重金属元素两个角度深入评估企鹅生物传输的生态环境影响。在东南极优选含鸟粪的典型湖泊沉积剖面作为主要研究载体，重点分析沉积色素和生物标志化合物等指标，开展这些指标的现代沉积过程研究，查明这些替代性指标的确切环境意义，据此识别中晚全新世以来湖泊沉积有机质的来源比例，并利用统计分析和软件技术定量地重建湖泊浮游植物群落结构和种群丰度的变化，在同一时间标尺上对比企鹅数量变化历史记录，同时结合典型重金属元素总量和形态在沉积剖面中的变化特征，从历史角度揭示这种独特的生物传输过程对南极湖泊生态环境变化造成的影响，并探讨其机制。研究成果将有助于我们在全球变化背景下更好地评估脆弱的南极湖泊生态系统对气候变化和生物传输的响应过程，为制定保护南极自然生态环境的对策和措施提供科学资料。

全球气候变化背景下南极企鹅种群数量在时间和空间上发生了大的变化，但目前我们对于这些南极无冰区上大量分布的生物种群对陆地湖泊生态系统的影响还缺乏足够的认识。项目组成员分别赴东南极罗斯海维多利亚地和南极半岛长城站地区开展了野外科学考察，采集了大量样品。室内开展了色素、有机生物标志物及其单体碳同位素、无机元素以及不同形态氮同位素等分析，并辅以AMS14C定年和基本理化性质分析。应用生态地质学多学科交叉的研究方法对获得的数据开展了深入研究，从氮、磷营养成分和元素循环等角度出发探讨了生物传输作用对陆地湖泊生态系统的影响，重点解析了企鹅粪输入对湖泊浮游植物群落生态的可能影响、生物传输对植物用氮策略的影响、沉积物中长链烷基类脂来源及其生态环境指示意义，以及湖泊沉积物中元素的生物地球化学循环过程。企鹅生物传输带来的营养成分促进了水生藻类的生长，提高了湖泊初级生产力，尤其是绿藻等藻类的生长。不同形态氮含量及其氮同位素组成分析表明，企鹅的生物传输对陆地土壤、植物以及周围的水生生态系统的氮循环过程均产生了显著影响。磷形态分析结果表明企鹅粪的输入显著提高了沉积物中生物可利用磷的含量，其中铁/铝结合态磷（Fe/Al-P）和有机磷（OP）在磷的生物地球化学循环中具有重要的作用。长链烷基类脂及其碳同位素分析发现，东南极未受生物粪影响的湖泊沉积物中大量的长链烷基类脂主要来源于异养微生物，粪土沉积物中C16和C26脂肪酸δ13C值可以用来指示历史时期企鹅和海豹数量变化。此外，对不同有机质来源的沉积物中元素地球化学特征分析发现，生物粪的输入和沉积环境的变化显著影响了沉积剖面中元素的环境地球化学行为。综合已有的研究结果，在全球偏远地区开展了生物传输作用过程和影响的对比研究。这些研究结果有助于我们更好地预测南极陆地湖泊生态环境未来可能发生的变化，从而为更好地制定保护南极自然生态环境的对策和措施提供科学依据。