An interdisciplinary approach to monitoring the hydroecology of thermokarst lakes in Old Crow Flats, Yukon Territory, Canada by Jana-marie Edesse Tondu A thesis presented to the University of Waterloo in fulfillment of the thesis requirement for the degree of Master of Science in Biology Waterloo, Ontario, Canada, 2012 © Jana-marie Edesse Tondu 2012 AUTHOR'S DECLARATION I hereby declare that I am the sole author of this thesis. This is a true copy of the thesis, including any required final revisions, as accepted by my examiners. I understand that my thesis may be made electronically available to the public. ii Abstract Lake-rich thermokarst landscapes, such as Old Crow Flats (OCF) in northern Yukon, Canada have been identified as amongst the most vulnerable to climate change. This has raised concerns of the Vuntut Gwitchin First Nation (VGFN) and Parks Canada (Vuntut National Park) about the ecological integrity of this significant wetland. The influence of climate change on the hydroecological conditions of thermokarst lakes are complex and vary across the landscape, thus long-term hydroecological monitoring is essential to adequately assess the ecological integrity of the aquatic ecosystem and how it is changing over time. In a genuine interdisciplinary and collaborative approach, this thesis establishes an integrated approach using isotope hydrology, aquatic ecology, and paleolimnology to develop a robust long-term aquatic monitoring program that has already been adopted by Parks Canada. In collaboration with Parks Canada, 14 of 58 lakes that were previously studied during the International Polar Year from 2007-09 were selected to represent monitoring lakes. Lakes were sampled in early June and late August/early September 2010-11. Water samples for analysis of hydrogen and oxygen isotope composition and chemistry (i.e., ions and nutrients) were collected to track hydrological and limnological conditions. Artificial substrates were deployed in June and accrued algae were collected at the end of the ice-free season to assess community composition and abundance. Sediment coring was conducted in a culturally-significant lake (Zelma Lake – OCF06) to reconstruct long-term baseline hydroecological conditions over the past three centuries. Radiometric dating techniques (137Cs, 210Pb) were used to develop a sediment core chronology. Baseline hydroecological conditions were reconstructed through analyses of loss-on-ignition, bulk organic carbon and nitrogen elemental and isotope compositions, and pigments. iii Meteorological data and a multi-year evaporation pan experiment were used to develop a robust isotope framework, which provides the basis for interpreting five years (2007-11) of lake water isotope measurements and deriving knowledge of hydrological conditions for the monitoring lakes. Using this framework and the coupled-isotope tracer method, isotopic compositions of input water (δI) and evaporation-to-inflow (E/I) ratios were calculated and provide key hydrological information for each sampling interval. δI values distinguish snowmelt- and rainfall-sourced lakes, with δP representing a threshold between the two isotopic-based hydrologic regimes. A Mann- Kendall test showed that three lakes (OCF11, 26, and 49) displayed significant increasing trends in δI values indicating a potential transition from snowmelt-sourced to rainfall-sourced isotope-based hydrologic-regimes. E/I ratios >0.5 signifies lakes that are evaporation-dominated with positive water balances and E/I ratios >1 indicates lakes that are evaporation-dominated with negative water balances. Six lakes in OCF (OCF06, 19, 37, 46, 49, and 58) surpass the 0.5 threshold and three of these lakes (OCF06, 19, and 46) crossed the significant evaporation threshold (E/I > 1) during dry climatic conditions. Multi-proxy paleolimnology analysis conducted on Zelma Lake reveals different hydroecological transitions during the past ~330 years that include: phase 1 (~1678-1900) characterized by stable hydroecological conditions; thermokarst expansion (~1900-1943) marked by decreases in productivity; phase 2 (~1943-2007) distinguished by increasing productivity; and a post drainage phase following rapid drainage in 2007 characterized by further increases in productivity. The stratigraphy of Zelma Lake shows that hydroecological conditions in dynamic landscapes such as OCF are complex and require multi-proxy paleolimnological analysis. In particular, organic matter, 13 δ Corg, and pigment concentrations are important parameters to consider when interpreting past hydroecological conditions, thermokarst expansion, and lake drainage events. iv Acknowledgements “Wherever you fly, you’ll be the best. Wherever you go, you will top all the rest. Except when you don’t, because sometimes you won’t. You can get all hung up, you can get so confused. But on you will go, because that is not for you. And will you succeed? Yes! You will indeed!” - Dr. Seuss I would like to thank my supervisors, Brent Wolfe and Roland Hall, for your continued support in all my endeavors, your constant encouragement, your enduring enthusiasm, your positive reinforcement, and buying beer at the Grad House. Brent, thank-you for always being excited about new accomplishments and reading them promptly, for never telling me exactly what to do (much to my dismay) and allowing me to figure things out, for reminding me that I can accomplish tasks when I feel they are unattainable, and for challenging me. Roland, thank-you for your positive attitude, for always answering my random questions, and for listening when I just needed to talk about data to understand it. I would also like to thank my committee member and neighbour, Tom Edwards, for your boundless entertainment, conversations at the Grad House, and throwing down the odd roll of toilet paper when needed. I would like to thank Bill Taylor for being on my committee, for letting me borrow lab equipment, and for always having an open-door. Thanks to Jon Sweetman for also being on my committee and providing feedback. I would like to thank Ian McDonald for being involved with this thesis and providing feedback, participating in all my milestones, providing resources and funding, and supporting my NSERC Northern Research Internship. I am grateful to Parks Canada staff (Leila Sumi, David Frost, Esau Schafer, and Jeffrey Peter) for helping me conduct field work and your unbelievable support when field logistics became exceedingly complicated. Thank-you for expanding the scope of the spring boat trip into Old Crow Flats to include sampling some of the monitoring lakes, organizing everything, and accommodating me. A special thanks to Joel Peter for your keen interest in this research project and guiding the trip, and to Sam Darling for coordinating the return of my precious samples, thesis-vent sessions, and all of your encouragement. I would like to thank the Vuntut Gwitchin Government (VGG) for supporting this research project and providing key resources. In particular, I would like to thank Shel Graupe, Lance Nagwon, v James Itsi, Megan Williams, Edna Kyikavichik, Dick Mahoney, Danny Kassi, and Mary-Jane Mossess for all your help and support with field work and logistics. Thanks to Steve Climie for always letting me transform the school kitchen into a laboratory. Thanks to Florence Netro for lending me your canoe and allowing me to sample Mary Netro Lake. I would also like to thank the VGG for inviting me to participate in Science Camp and purchasing my flight from Whitehorse to Old Crow. A special thanks to Jessica Peter for opening your home and letting me stay with you. I would also like to thank the community of Old Crow for being tremendously hospitable and generously filling my belly with too much food! I would like to thank all members of the Wolfe and Hall lab groups for your help to complete this research by providing critical feedback and sharing laughs. I have appreciated being part of a large, diverse research group that is always willing to help each other out. A special thanks to Ann Balasubramaniam, Kevin Turner, Katie Thomas, and Nick Sidhu for traveling to Old Crow with me, helping me collect samples, and transporting them to Waterloo. In particular, thanks to Ann Balasubramaniam and Kevin Turner for guiding me through field work and integrating me into the IPY project. Ann - I am indebted to your continuous support and countless conversations about Old Crow. Kevin – I appreciate all your help with water isotopes, answering my badgering emails, and making maps. I would also like to thank Lauren MacDonald for teaching me how to construct periphyton samplers, your technical guidance in the lab, and always delivering my water samples to NLET. Thanks to Johan Wiklund for developing sediment core chronologies and your input on lab methodologies. I would like to extend a big thank-you to Pete Thompson for all your help with statistics. I would like to especially thank the many friends that I have made in Waterloo, who have made Ontario not so terrible. Thank-you to Ann Balasubramaniam, Madeline Rosamond, Jennifer Hood, Pete Thompson, Jennifer Fresque-Baxter, Andrea Bartram, Brent Lazenby, Justin Harbin, Jessica Leung, and Marcelo Sousa for great memories and giving me heaps of moral support when I needed it. Thanks to the Grad House crew for always being there with a smile of your face; and to the Grad House for never increasing the price of Fireball! Lastly, I would like to thank my parents. I am grateful for your unwavering love and support in everything