Kevin W. Turner

Using Water Isotope Tracers to Develop the Hydrological Component of a Long-Term Aquatic Ecosystem Monitoring Program for a Northern Lake-Rich Landscape

Abstract Arctic lake-rich landscapes are vulnerable to climate change, but their remote locations present a challenge to develop effective approaches for monitoring hydroecological status and trends. Here, we structure the hydrological component of an aquatic ecosystem monitoring program that addresses concerns of Parks Canada (Vuntut National Park) and the Vuntut Gwitchin First Nation about changing water levels of Old Crow Flats (OCF), Yukon, Canada, a 5600-km2 thermokarst landscape recognized nationally and internationally for its ecological, historical, and cultural significance. The foundation of the monitoring program is 5 years (2007–2011) of water isotope data from 14 lakes situated in catchments that are representative of the land-cover and hydrological diversity of OCF. Isotopic compositions of input water (&dgr;I) and evaporation-to-inflow (E/I) ratios, calculated using the coupled-isotope tracer method, provide key hydrological metrics for each lake over the 5-year sampling interval. From these time series, we identify monitoring lakes that are sensitive to changes in snowmelt, rainfall, and evaporation, and demonstrate the use of the Mann-Kendall test for determining statistically significant trends in the roles of these hydrological processes on lake-water balances. These approaches will serve to identify lake hydrological responses to climate change and variability from ongoing water isotope monitoring by Parks Canada, in partnership with the Vuntut Gwitchin Government, Wilfrid Laurier University, and the University of Waterloo.

Paleolimnology of thermokarst lakes: a window into permafrost landscape evolution

Widespread across northern permafrost landscapes, thermokarst ponds and lakes provide vital wildlife habitat and play a key role in biogeochemical processes. Stored in the sediments of these typically shallow and dynamic waterbodies are rich sources of paleoenvironmental information whose potential has not yet been fully exploited, likely because of concerns over stratigraphic preservation and challenges to develop reliable sediment core chronologies. Here, we present an overview of recently derived informative paleolimnological reconstructions based on multiparameter analysis of sediment archives from permafrost aquatic basins. We include examples from across the Canadian North, Alaska, and Siberia that illustrate their value for providing insights into temporal patterns of lake inception, catchment erosion, aquatic productivity, hydrological evolution, and landscape disturbances. Although not captured in our survey, emerging research directions focused on carbon accumulation, storage, and balance hold m...

A synthesis of thermokarst lake water balance in high-latitude regions of North America from isotope tracers

Numerous studies utilizing remote sensing imagery and other methods have documented that thermokarst lakes are undergoing varied hydrological transitions in response to recent climate changes, from...

Limnological evolution of Zelma Lake, a recently drained thermokarst lake in Old Crow Flats (Yukon, Canada)

Evidence from remote sensing studies suggests that the frequency of thermokarst lake drainage events is increasing in response to climate change, but the consequences of these changes on the limnology of remaining waterbodies remain unknown. Here, we utilize a multiparameter paleolimnological record and post-drainage water isotope and chemistry monitoring to characterize the limnological evolution of Zelma Lake in Old Crow Flats, Yukon. During the early part of the record (~1678 to 1900 CE), analysis of geochemical variables and algal pigments indicate relatively stable limnological conditions. Abruptly beginning at ~1900, Zelma Lake experienced a 40 year phase of reduced production, likely resulting from thermokarst shoreline expansion and associated increases in turbidity and low light availability. This was followed by ~70 years of increasing production, likely from the stabilization of shorelines combined with a warming climate. Zelma Lake catastrophically drained in June 2007. Post-drainage condition...

Biotic responses to multiple aquatic and terrestrial gradients in shallow subarctic lakes (Old Crow Flats, Yukon, Canada).

Biotic communities in shallow northern lakes are frequently used to assess environmental change; however, complex interactions among multiple factors remain understudied. Here, we present analyses of a comprehensive data set that evaluates the influence input waters, catchment characteristics, limnology, and sediment properties on diatom and chironomid assemblages in surface sediments of ~49 shallow mainly thermokarst lakes in Old Crow Flats, Yukon. Multivariate analyses and ANOSIM tests identified that composition of diatom (119 taxa) and chironomid (68 taxa) assemblages differs significantly (p < 0.05) between lakes with snowmelt- versus rainfall-dominated input water. Redundancy analyses revealed strong correlation of limnological, sediment, and catchment variables with input waters. Variation partitioning analyses showed that unique effects of limnological variables account for the largest proportion of variation in diatom and chironomid assemblages (17.2% and 12.6%, respectively). Important independe...