Paleohydrology inferred from diatoms in northern latitude regions

Several recent studies have successfully applied diatom-based paleolimnolog ical techniques to infer past hydrological changes in arctic and subarctic regions. For example, we summarize arctic studies that attempt to determine changes in peat water content, flood frequency, river discharge, effective moisture and ice cover in northern regions. Some of the investigations are still in preliminary stages, but represent innovative approaches to study arctic and subarctic paleohydrology. New data demonstrate that lake depth, which may be related to changing hydrological conditions, is a significant variable influencing the distributions of diatom taxa in lake surface sedim ent calibration sets from Wood Buffalo National Park (WBNP), on the border of Alberta and the Northwest Territories, Canada, and from Fennoscandia (ma inly northwest Finland). Weighted averaging regression and calibration meth ods were used to develop quantitative inference models for lake depth using diatom assemblages preserved in surface sediments. The predictive abilitie s of the transfer functions were relatively high (for WBNP r(2) = 0.70 and RMSE = 2.6 m, and for Fennoscandia r(2) = 0.88 and RMSE = 1.8 m). However, evaluating the transfer functions using jack-knifing procedures indicated l ower predictive abilities, possibly reflecting the relatively small sample size and/or short gradients used in these calibration sets. Such transfer f unctions can be used to track overall trends in lake levels, and provide an objective assessment as to directions of changing lake levels. Any interpr etations of inferred lake levels, especially those related to climate chang e, must be made cautiously and must include some understanding of the local , present-day hydrological system.