Integrating pelagic consumers to global carbon budgets

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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.