Integrating pelagic consumers to global carbon budgets

冻土带土壤是地球上最大的有机碳库。气候变暖和永久冻土融化的相关变化增加了这种碳成为温室气体来源的风险。因此，有必要增进我们对加拿大高纬度生态系统及其对全球环境变化的反应的了解。该研究计划旨在研究众多的湖泊和池塘，这些湖泊和池塘可以覆盖北部50%或更多的表面积，并对北极生物多样性做出重大贡献。具体而言，研究将侧重于作为所有生命基础的碳的控制和性质，以及随后在北方湖泊中的循环和浮游动物（浮游动物）向大气的排放。北方的湖泊和池塘往往没有鱼，而在这些系统中，浮游动物可能很丰富，可能影响生态系统的总呼吸率。温度可能是影响浮游动物生产和呼吸速率的一个主要因素;自1950年代以来，北极的温度平均上升了约2-3 ℃，而且这一趋势仍在继续。温度升高已被证明会导致永久冻土的加速融化，以及更多的碳从土壤基质释放到淡水中。从周围集水区进入湖泊的有机碳物质（陆地碳）可能在水生食物网中矿化，并作为影响全球碳预算的CO2转移到大气中。该项目将评估以下假设：周围土壤的变化改变了浮游动物的碳代谢，从而对淡水水生系统的温室气体排放产生了重大影响。该项目将确定浮游动物生物量对亚北极池塘中浮游生物量总量的贡献，测量一系列亚北极湖泊和池塘中浮游动物生产、呼吸和碳摄入的空间和季节变化，包括因永冻土融化而增加外来碳的沃茨。还将进行一系列实验室实验，以确定浮游动物的新陈代谢如何对温度变化作出反应。这些目标将大大进一步提高对湖泊和池塘的认识，这是加拿大北方景观的主要组成部分，并将允许评估加拿大苔原碳储量中有多少可以动员和转化为温室气体，并通过浮游动物呼吸作用通风到大气中。该项目将在北方魁北克靠近Kuujjuarapik村（北纬55度，西经77度）进行。该地区有丰富的小湖泊和池塘，位于北美树线附近，处于一个不连续的永久冻土区，正在加速融化。

Frozen tundra soils are of the Earth’s largest pools of organic carbon. Climate warming and associated changes in permafrost thawing have increased the risk that this carbon becomes a source of greenhouse gases. There is therefore a need to increase our understanding of Canada’s high latitude ecosystems and their response to global environmental change. This research program is to study the numerous lakes and ponds that can cover 50 % or more of the surface area in the north and that contribute significantly to arctic biodiversity. Specifically the research will focus on the control and nature of carbon which is the basis for all life, and its subsequent cycling in northern lakes and emissions to atmosphere from planktonic animals (zooplankton). Fish are often absent from northern lakes and ponds, and in such systems zooplankton can be abundant, potentially affecting the total respiration rate of the ecosystem. Temperature is likely to be a major factor affecting zooplankton production and respiration rates; on average it has risen about 2-3°C since the 1950s in the Arctic and the trend is continuing. Temperature increase has been shown to lead to accelerated thawing of permafrost, and greater release of carbon from the soil matrix to freshwaters. Organic carbon materials that enter a lake from its surrounding catchment (terrestrial carbon) are likely to be mineralized in the aquatic food web and transferred to the atmosphere as CO2 influencing global carbon budgets. The project will evaluate the hypothesis that changes in the surrounding soils modify the carbon metabolism of zooplankton and hence strongly influence greenhouse gas emissions from the freshwater aquatic systems. The project will determine the contribution of zooplankton biomass to the total pelagic biomass in subarctic ponds, measure the spatial and seasonal variability in zooplankton production, respiration and carbon ingestion in a range of subarctic lakes and ponds, including waters that have been subjected to increases in allochthonous carbon from the thawing permafrost. A set of laboratory experiments will also be undertaken to determine how zooplankton metabolism responds to changes in temperature. These objectives will greatly further improve the understanding of lakes and ponds, a major component of Canada’s northern landscape, and will allow an assessment of how much of Canada's tundra carbon stocks may be mobilised and converted to greenhouse gases and ventilated to the atmosphere via zooplankton respiration. The project will be conducted in northern Quebec close to the village of Kuujjuarapik (55ºN, 77ºW). The area is rich in small lakes and ponds and is located near the North American treeline in a discontinuous permafrost region that is thawing at an accelerated rate.