A PALEOLIMNOLOGICAL ASSESSMENT OF RECENT ENVIRONMENTAL CHANGES IN LAKES OF THE WESTERN CANADIAN ARCTIC by Joshua Robert Thienpont A thesis submitted to the Department of Biology in conformity with the requirements for the degree of Doctor of Philosophy Queen’s University Kingston, Ontario, Canada (April, 2013) Copyright © Joshua Thienpont, 2013 Abstract The freshwater ecosystems in the western Canadian Arctic are threatened by multiple and interacting stressors, as high-latitude regions are undergoing rapid change resulting from climate warming and other human-related activities. However, due to the paucity or absence of monitoring data, little is known about long-term changes in lake ecosystems. This thesis addresses this knowledge gap by using paleolimnological techniques to assess the responses of freshwater ecosystems in the Mackenzie Delta region to three major stressors predicted to become increasingly important, namely impacts from accelerated permafrost thaw, marine storm surges, and hydrocarbon exploration. Using a paired-lake design, six reference lakes were compared to six lakes impacted by retrogressive thaw slumps, an important form of thermokarst in this region. While all of the study lakes have undergone ecologically significant biological changes over the last ~200 years as a result of warming, lakes impacted by thaw slumps have changed more due to the cumulative effects of warming and heightened permafrost thaw. In addition to warming, the outer Mackenzie Delta is a low-lying landscape that is susceptible to inundation by marine storm surges from the Beaufort Sea. A large storm event in 1999 flooded >10,000 hectares of the outer delta. My paleolimnological data show that this marine intrusion resulted in diatom assemblage changes in flooded lakes on a landscape-scale that were unprecedented in the recent past, suggesting recent warming, and associated sea-ice decreases, are making this region more susceptible to storm-surge damage. Finally, lakes impacted by sumps used to dispose of the drilling by-products of hydrocarbon exploration exhibit distinct water chemistry, and are particularly elevated in potassium and chloride, which form a major component of some drilling fluids. Related to this, a discernible change in cladoceran assemblages coeval with the time of sump construction suggest that sump failure has resulted in ii biological changes in affected lakes. Collectively, this research shows that the ecosystems of the western Canadian Arctic are under threat from multiple stressors that have resulted in changes to the chemistry and biology of the freshwater resources of this region. iii Co-Authorship Chapter 2 was co-authored by Kathleen Rühland, Michael Pisaric, Steven Kokelj, Linda Kimpe, Jules Blais and John Smol and represents original work as part of my PhD thesis. I designed the project, conducted the field work, analyzed all diatom samples, conducted all statistical analyses and was the primary author on this paper. This chapter has been published separately. Thienpont J.R., Rühland, K.M., Pisaric, M.F.J., Kokelj, S.V., Kimpe, L.E., Blais, J.M., and Smol, J.P. 2013. Biological responses to permafrost thaw slumping in Canadian Arctic lakes. Freshwater Biology 58 (2): 337–353. Chapter 3 was co-authored by Daniel Johnson, Holly Nesbitt, Steven Kokelj, Michael Pisaric, and John Smol and represents original work completed as part of my PhD thesis. I designed the research, conducted all field work, analyzed diatom samples from one lake, conducted all statistical analyses and was the primary author on this paper. This chapter has been published separately. Thienpont, J.R., Johnson, D., Nesbitt, H., Kokelj, S.V., Pisaric, M.F.J., and Smol, J.P. 2012. Arctic coastal freshwater ecosystem responses to a major saltwater intrusion: a landscape-scale palaeolimnological analysis. The Holocene 22 (12): 1447-1456. Chapter 4 was co-authored by Steven Kokelj, Jennifer Korosi, Elisa Cheng, Cyndy Desjardins, Linda Kimpe, Jules Blais, Michael Pisaric and John Smol and represents original work as part of my PhD thesis. I designed the research, conducted all field work related to sediment core collection, analyzed the modern limnological data, analyzed all of the diatom samples and the cladoceran samples from one sediment core, conducted all statistical analyses and was the primary author on this paper. This chapter has been formatted for submission to Proceedings of the National Academy of Sciences (USA). Thienpont, J.R., Kokelj, S.V., Korosi, J.B., Cheng, E., Desjardins, C., Kimpe, L.E., Blais, J.M., Pisaric, M.F.J., and Smol, J.P. Exploratory hydrocarbon drilling impacts to Arctic lake ecosystems. In prep. Appendix A was co-authored by Michael Pisaric, Steven Kokelj, Holly Nesbitt, Trevor Lantz, Steven Solomon (deceased), and John Smol. This chapter represents original work completed during the course of my PhD. I co-designed the research, conducted all field work related to lake sampling, analyzed diatom samples from the DZO-29 piston core, analyzed the paleolimnological data, and co-authored the manuscript. This chapter has been published separately. Pisaric, M.F.J.*, Thienpont, J.R.*, Kokelj, S.V., Nesbitt, H., Lantz, T.C., Solomon, S., and Smol, J.P. 2011. Impacts of a recent storm surge on an Arctic delta ecosystem examined in the context of the last millennium. Proceedings of the National Academy of Sciences (USA) 108 (22): 8960-8965. *Both authors contributed equally to the publication. iv Acknowledgements “The thing the ecologically illiterate don’t realize about an ecosystem is that it’s a system. A system! A system maintains a certain fluid stability that can be destroyed by a misstep in just one niche. A system has order, a flowing from point to point. If something dams the flow, order collapses. The untrained might miss that collapse until it was too late. That’s why the highest function of ecology is the understanding of consequences.” - Frank Herbert’s Dune I first wish to acknowledge and thank John Smol, without whom this thesis would never have been possible. Thank you for taking a chance on a prospective 3rd year undergraduate summer student, undoubtedly just one application in a very large pile presented before you, as well as for the encouragement, mentorship and, equally importantly, laughs over the last several years. Thank you also to Mike Pisaric, Steve Kokelj and Kat Rühland for your assistance, knowledge and friendship throughout my degree, I could not have done it without your help. I would like to thank Jules Blais and Linda Kimpe for their assistance and guidance. I would like to thank Brian Cumming and Melissa Lafrenière for providing feedback as members of my committee. To the members of the PEARL group, past and present, thank you for your friendship over the years. In particular, thank you to Adam Jeziorski, for holding the heavy bag when the only solution to a persistent scientific quandary was a good round of kick boxing. To my parents and sister, thank you for your love and support. The gift of education is one of the most important parents can give their children, and I thank you for the many sacrifices v you have made, without which I would not be where I am today. Thank you to all of my extended family, the Thienpont’s, Scott’s and Korosi’s, for your love and support. Finally, I end by thanking my wife Jenny Korosi. This process was so much more enjoyable because we undertook it together. Without your encouragement, love, advice and assistance this wouldn’t have been possible. vi Table of Contents Abstract . ii Co-authorship . iv Acknowledgements . v List of Abbreviations . xii List of Tables . .xiii List of Figures . xiv Chapter 1: General introduction and literature review . 1 Thesis Objectives . 7 Literature Cited . 10 Chapter 2: Biological responses to permafrost thaw slumping in Canadian Arctic lakes . .14 Summary . 15 Introduction . 17 Methods . 21 Paired study design: site description . 22 Sediment core collection and diatom analyses . 24 Statistical analyses . 26 Results . 28 Discussion . 37 Regional climate warming . 37 Impacts of thaw slumping on diatom assemblage structure and lake habitat . 39 vii Chemical changes due to slumping . 42 Acknowledgements . 45 References . 46 Supporting Information . 51 Chapter 3: Arctic coastal freshwater ecosystem responses to a major saltwater intrusion: a landscape-scale palaeolimnological analysis . 66 Abstract . 67 Introduction . 68 Methods . 70 Site description . 70 Lake sampling and sample preparation . 72 Geochronology and data analyses . 73 Results . .75 Relationships among limnological variables . 75 Diatom analyses . 75 Discussion . 81 Synchronous and unmatched impacts of the 1999 storm surge . 81 Assessing post-storm surge recovery . 85 Other diatom assemblage changes . 86 Conclusions . 88 Acknowledgements . 88 Funding . 89 viii References . .89 Chapter 4: Exploratory hydrocarbon drilling impacts to Arctic lake ecosystems . .93 Abstract . .94 Introduction . .95 Results and Discussion . ..