PALEOLIMNOLOGICAL ASSESSMENT OF HOLOCENE CLIMATIC AND ENVIRONMENTAL CHANGE IN TWO LAKES LOCATED IN DIFFERENT REGIONS OF THE CANADIAN ARCTIC TUNDRA by C. Alyson Paul A thesis submitted to the Department of Biology in conformity with the requirements for the degree of Master of Science Queen's University Kingston, Ontario, Canada October 2008 Copyright © C. Alyson Paul, 2008 ABSTRACT Paleoclimatic research in the Canadian Arctic has increased in recent decades; however, there is still much to learn about the nature and extent of past climate change in this vast and environmentally sensitive region. This thesis uses primarily diatom assemblages in dated lake sediment cores as proxy indicators to infer how climate has changed over the Holocene in two very different lakes in the central Canadian Arctic: one located in a poorly-studied geographical region, and another possessing limnological characteristics that are unusual in an Arctic context. Lake TK-2 is located in the low Arctic tundra. Paleolimnological studies from this region are lacking, as most have centered on sites in the High Arctic Archipelago or around Subarctic treeline. Marked changes in the diatom assemblages in TK-2 throughout the Holocene included potential evidence for the 8.2k cooling event, which has not been previously reported from other Canadian Arctic paleolimnological studies. In addition, diatom shifts occurring ~7000 and ~3500 cal yr BP are indicative of mid- Holocene warming and subsequent Neoglacial cooling, respectively, the timings of which agree with those from other studies farther south. Finally, shifts in the diatom assemblages in the upper sediment layers, beginning in the early-to-mid 19th century, are consistent with reduced ice cover, related to recent warming. Stygge Nunatak Pond, a small, closed-basin pond located on a nunatak in the High Arctic on Ellesmere Island, is characterized by water with unusually high ionic concentrations for an inland Arctic pond. As in TK-2, Stygge’s diatom assemblages changed substantially throughout the Holocene, but especially in the most recent sediments. Diatom shifts near ~10,500 cal yr BP suggest an early onset for the Holocene ii Thermal Maximum (as well as for the successive Neoglacial cooling trend) in this region, consistent with previous studies from the High Arctic. Marked changes in diatom assemblages occurred in the most recent sediments, and, like those in TK-2, are indicative of climate warming and reduced ice cover, as well as increased ionic concentration due to enhanced evaporative concentration. The dynamic nature of the diatom assemblage changes at the Stygge site suggests that sediments from these rare athalassic ponds represent an especially sensitive archive of Arctic climatic and environmental change. iii ACKNOWLEDGEMENTS First, I would like to thank John Smol for putting up with me through both of my University degrees here at Queen’s. Thank you for your kindness, patience, and thoughtful supervision over these several years. Thanks are also due to Kathleen Rühland, for her tireless help with everything from microscopy to taxonomy (and beyond), and for maintaining a sense of humour through it all. Without her, this thesis would certainly not have been possible. Thank you to Marianne Douglas for her co- supervision, and her company during the Arctic Field Season, as well as to Brian Cumming and Scott Lamoureux for being on my committee and providing helpful insights into my research. A special thank you to Dr. Wes Blake, Jr., who played an instrumental role in the development of the Stygge Nunatak Pond project, and who has gone above and beyond in his efforts to share his knowledge and expertise with me. Similarly, thanks to Robert Gilbert for helping me work through the conundrum that was Stygge’s ice. I would also like to thank my fellow PEARLites (past, present and honourary) for their help and companionship along the way. Thanks for sharing in my insanity and reminding me that I was never alone. Finally, a huge, heartfelt thank you is in order for my wonderful family and friends, both near and far, for your unconditional love and support throughout this experience. Thank you for helping me to keep things in perspective. I love you all so much. iv TABLE OF CONTENTS Abstract...........................................................................................................................................ii Acknowledgments..........................................................................................................................iv Table of Contents............................................................................................................................v List of Tables..................................................................................................................................vi List of Figures...............................................................................................................................vii List of Appendices.......................................................................................................................viii Chapter 1: General Introduction and Literature Review............................................................1 Recent Climate Change in the Arctic.........................................................................................1 Paleolimnology and Diatoms as Paleoindicators......................................................................3 Paleolimnology in the Canadian Arctic.....................................................................................5 References...................................................................................................................................8 Chapter 2: Diatom-inferred Holocene climatic and environmental change in a lake from the continental Canadian Low Arctic, Nunavut...............................................................................13 Abstract....................................................................................................................................14 Introduction..............................................................................................................................16 Methods....................................................................................................................................22 Results......................................................................................................................................27 Discussion................................................................................................................................33 Summary and Conclusions.......................................................................................................51 References.................................................................................................................................54 Figure Captions........................................................................................................................64 Figures......................................................................................................................................65 Tables.......................................................................................................................................70 Chapter 3: Diatom-inferred Holocene climatic and environmental change in an unusually saline high Arctic nunatak pond on Ellesmere Island (Nunavut, Canada).............................................................................................................................72 Abstract....................................................................................................................................73 Introduction..............................................................................................................................75 Methods....................................................................................................................................79 Results......................................................................................................................................85 Discussion................................................................................................................................91 Summary and Conclusions.....................................................................................................108 References...............................................................................................................................110 Figure Captions......................................................................................................................118 Figures....................................................................................................................................120 Tables.....................................................................................................................................128 Chapter 4: General Discussion and Conclusions......................................................................131 Appendices...................................................................................................................................138 v LIST OF TABLES Chapter 2 Table 2.1…….……………………………………………………………………………………70 Summary of the key modern surface water chemistry and other limnological measurements from Lake TK-2, collected on August 7, 1996. Table 2.2…….……………………………………………………………………………………71