Limnology and paleoecology of lakes

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Arctic regions have been repeatedly identified as bellwethers for the study of global environmental change. However, due to the lack of long-term data, it is impossible to determine the timing and magnitude of many ecosystem changes, and to test hypotheses, define natural variability, and evaluate models. Consequently, indirect proxy methods, such as using information preserved in lake sediments (i.e. paleolimnology) must be used to address many scientifically and socially-relevant questions. During my 26 year research program in the Arctic, which dovetails with our ongoing paleolimnological work, we have recorded marked limnological changes as high Arctic ponds become less ice-covered and shallower with warming until many of the smaller sites finally dried up totally in July 2006. We will study how these unprecedented ecological changes are affecting Arctic ecosystems, as well as comparable paleolimnological and ecological changes in other Arctic regions. A second new research area will focus our approaches on subarctic peatland profiles, which potentially offer higher temporal resolution of environmental change than Arctic lake sediments, and may be more closely linked to precipitation and evaporation ratios. Our main focus will be a transect of peat and permafrost cores from the Hudson Bay Lowlands region, which is a region that is critically important for our understanding of climatic and environmental change. A parallel paleolimnological study of 15 lakes, working in collaboration with process-based scientists, will complement this boreal to subarctic transect, and determine how climate-related changes in ice cover and/or thermal stratification patterns are affecting lakes in these poorly studied regions, bordering on temperate and sub-arctic ecosystems. Finally, we will develop and apply new paleolimnological methods (based largely on invertebrate indicators) to track a new and previously under-recognized environmental problem affecting softwater boreal lakes around the world: the decline in lakewater calcium concentrations.