Long-term perspectives on aquatic ecosystem change with thawing permafrost

永久冻土融化导致水生生态系统变化的长期视角

• 批准号: RGPIN-2017-05663
• 负责人: Korosi, Jennifer
• 金额: $ 1.97万
• 依托单位: York University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2018
• 资助国家: 加拿大
• 起止时间: 2018-01-01 至 2019-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=655907
• 关键词: Long; term; perspectives; aquatic; ecosystem

Approximately 25% of all lakes globally are located in permafrost regions, and these lakes are among the most vulnerable to climate warming through accelerated rates of permafrost thaw. A long-term perspective is needed to understand how lake ecosystems are responding to permafrost degradation, in order to place recent changes in the context of natural ecosystem variability. My research will use lake sediment cores to reconstruct lake histories (centennial to millennial timescales), in order to address key knowledge gaps in our understanding of the responses of lake ecosystems to the transformative landscape changes occurring as a result of permafrost thaw. I will explore long-term aquatic ecosystem changes under two contrasting scenarios of thawing permafrost in Canada's Northwest Territories. The first scenario focuses on lakes at the southern limit of permafrost (near Hay River), where thawing permafrost leads to the conversion of forested permafrost-supported peat plateaus into wetlands. These landscape changes alter terrestrial carbon run-off to lakes, which has implications for carbon and contaminant cycling, and ecological interactions among aquatic biota. The second scenario examines a spectacular form of permafrost degradation, retrogressive thaw slumps that form on the shorelines of lakes in areas of high ground-ice content, such as near Inuvik, NT. Thaw slump development releases large amounts of inorganic material (such as clay particles) to lakes, which scavenges organic carbon and nutrients out of the water column, and increases water clarity. The increase in water clarity following thaw slumping may increase the exposure of aquatic biota to harmful UV radiation, a potential stressor in slump-impacted lakes that has yet to be thoroughly investigated. The study of lake histories on millennial timescales, under both permafrost thaw scenarios, will allow me to reconstruct ecosystem conditions during past warm periods as a frame of reference from which to evaluate current conditions under recent human-induced climate warming. The north hosts an abundance of freshwater resources, and permafrost thaw will continue to intensify as a stressor on these ecosystems. By examining lake responses to this stressor over varying temporal and spatial scales, my research will provide insights into the fate of aquatic food webs under future climate warming, contributing to the protection of healthy and diverse aquatic ecosystems in northern Canada.

全球大约25%的湖泊位于永久冻土区，这些湖泊是最容易受到气候变暖影响的湖泊之一，因为永久冻土融化的速度加快。需要从长远的角度来了解湖泊生态系统如何应对冻土退化，以便将最近的变化置于自然生态系统可变性的背景下。我的研究将使用湖泊沉积物岩心重建湖泊历史（百年到千年的时间尺度），以解决我们对湖泊生态系统对永久冻土融化导致的变革性景观变化的反应的理解中的关键知识空白。我将探讨长期的水生生态系统的变化下，在加拿大西北地区的永久冻土融化的两个对比方案。第一种情况的重点是湖泊在南部限制的永久冻土（干草河附近），融化的永久冻土导致森林永久冻土支持泥炭高原转化为湿地。这些景观变化改变了陆地碳径流到湖泊，这对碳和污染物循环以及水生生物群之间的生态相互作用产生了影响。第二种情况考察了永久冻土退化的一种壮观形式，即在地冰含量高的地区（例如北领地因纽维克附近）的湖泊海岸线上形成的倒退性解冻塌陷。融化滑塌的发展释放了大量的无机物质（如粘土颗粒）到湖泊，这清除了水柱中的有机碳和营养物质，并增加了水的透明度。解冻滑塌后水的透明度增加可能会增加水生生物群对有害紫外线辐射的暴露，这是受滑塌影响的湖泊的一个潜在压力源，尚未进行彻底调查。在这两种永久冻土融化情景下，对千年时间尺度上的湖泊历史的研究将使我能够重建过去温暖时期的生态系统条件，作为评估近期人类引起的气候变暖下当前条件的参考框架。北方拥有丰富的淡水资源，永久冻土融化将继续加剧，成为这些生态系统的压力源。通过研究湖泊在不同的时间和空间尺度上对这种应激源的反应，我的研究将为未来气候变暖下水生食物网的命运提供见解，有助于保护加拿大北方健康多样的水生生态系统。