Simmatis Brigitte SG 201812
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SEDIMENTARY MIDGES AS PALEOINDICATORS OF DEEP- WATER OXYGEN CONDITIONS ACROSS A BROAD TROPHIC GRADIENT IN BOREAL LAKES by BRIGITTE SHIRLEY GERTRUD SIMMATIS 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 (December 2018) Copyright © Brigitte Shirley Gertrud Simmatis, 2018 Abstract Cultural eutrophication, the addition of excess nutrients to an aquatic system, is a significant water quality concern that often promotes excess algal growth and deep-water oxygen depletion. Deep-water oxygen also influences internal nutrient loading and is an important parameter used to assess cold-water fish habitat, though long-term data are often unavailable. Chironomid (Diptera: Chironomidae) assemblages have been shown to change with deep-water oxygen concentrations and can therefore be used to reconstruct these missing data sets. This thesis used paleolimnological techniques to analyze inferred whole-lake primary production, sedimentary chironomid assemblages, and inferred volume-weighted hypolimnetic oxygen to determine how cold-water fish habitat has changed through time. I will also examine whether biological recovery after nutrient- targeting remediation was introduced was evident in sedimentary chironomid assemblages. I focused on two lakes with increasing inferred whole-lake primary production (Muskrat and Stoco lakes, Ontario) and one lake with decreasing inferred primary production (Lac Duhamel, near Mont Tremblant, Québec) over time. The majority of change in response to elevated inferred whole-lake primary production is evident in littoral taxa and head capsule concentrations, though oxy-conforming profundal taxa (e.g. Micropsectra) did respond to increased whole-lake primary production. Overall, deep-water oxygen recovery after nutrient-targeting remediation was not evident in the sedimentary chironomid assemblages and that there were generally only subtle responses to elevated whole-lake primary production. Many of our lakes had historically low deep-water oxygen concentrations that were suboptimal for cold-water fish throughout their sedimentary records, with two lakes experiencing modest declines ii after there were increases in whole-lake primary production. These paleolimnological data can be used to set realistic mitigation targets for deep-water oxygen conditions and cold-water fish habitat restoration. iii Co-Authorship The chapters in this thesis have not been submitted for publication. Below, I describe my contributions to each data chapter Chapter 2 will likely be co-authored by Irene Gregory-Eaves, Dermot Antoniades, and John P. Smol. I participated in field work, dated the sediment core, analysed chironomids, sedimentary chlorophyll a, performed statistical analyses, and was the primary author of the chapter. Irene Gregory-Eaves and Dermot Antoniades coordinated field work. John Smol oversaw study design and data interpretation. Chapter 3 will likely be co-authored by Clare Nelligan, Adam Jeziorski, and Andrew M. Paterson. I analysed chironomids, performed statistical analysis and was the primary author of the chapter. Clare Nelligan completed the diatom analysis. Clare Nelligan and Adam Jeziorski dated the sediment core and completed the sedimentary chlorophyll a analyses. Chapter 4 will likely be co-authored by Irene Gregory-Eaves, Dermot Antoniades, and John P. Smol. I analysed chironomids, dated the sediment core, performed the sedimentary chlorophyll a analyses, performed statistical analyses, and was the primary author of the chapter. Appendix A will likely be co-authored by Irene Gregory-Eaves, Dermot Antoniades, and John P. Smol. I analysed chironomids, dated the sediment core, sedimentary chlorophyll a, analysed the data, and was the primary author of the chapter. iv Acknowledgments “Nothing will work unless you do.” – Maya Angelou I wish to thank my supervisor, Dr. John Smol, for providing not only the opportunity to spend 3 great, whirlwind years studying with PEARL, but for the abundant opportunities that enriched the experience. I would also like to thank my committee members, Drs. Paul Blanchfield and Brian Cumming, for their advice, support, and guidance. I would also like to thank all of the members at PEARL for their advice, friendship and support. I would not have maintained what little sanity I have left without you. A special thank you to Emily, Clare and Adam, for your advice, support and help with editing. I wish to thank the NSERC LakePulse Network and field participants that have helped organize, coordinate, and collect samples, with a special acknowledgement to those that helped collect the sediment cores used in this thesis. Finally, and most of all, I would like to thank my family, Leif, Holger and Darlene, who have given their unwavering and immeasurable support since I started at Queen’s. v Table of Contents Abstract ............................................................................................................................... ii Co-Authorship.................................................................................................................... iv Acknowledgments............................................................................................................... v Table of Contents ............................................................................................................... vi List of Tables ..................................................................................................................... ix List of Figures ..................................................................................................................... x List of Abbreviations ......................................................................................................... xi Chapter 1: General Introduction and Literature Review ..................................................... 1 Paleolimnology ............................................................................................................... 4 Invertebrate Subfossils as Paleoindicators ...................................................................... 5 Chironomids as paleoindicators of oxygen................................................................. 6 Chaoborids as indicators of deep-water anoxia ....................................................... 10 Other invertebrate indicators ................................................................................... 10 Thesis Objectives .......................................................................................................... 11 References ..................................................................................................................... 14 Chapter 2: Low-oxygen conditions persist in Stoco Lake (Tweed, Ontario, CA) after sewage treatment installation as inferred from sedimentary Chironomidae, Chaoboridae, and Simuliidae (Diptera) subfossil assemblages............................................................... 22 Abstract ......................................................................................................................... 22 Introduction ................................................................................................................... 24 Methods......................................................................................................................... 28 Site description.......................................................................................................... 28 Core collection and chronology................................................................................ 30 Dipteran remains ...................................................................................................... 31 VRS-Inferred Whole Lake Primary Production ........................................................ 32 Results ........................................................................................................................... 33 Discussion ..................................................................................................................... 35 References ..................................................................................................................... 44 Figures........................................................................................................................... 53 Supplemental Figures.................................................................................................... 57 vi Chapter 3: Assessing oxythermal Lake Trout (Salvelinus namaycush) habitat in Muskrat Lake (Cobden, Ontario) using sedimentary Chironomidae (Diptera) assemblages over the past ~200 years ................................................................................................................. 63 Abstract ......................................................................................................................... 63 Introduction ................................................................................................................... 65 Methods......................................................................................................................... 68 Study Site ................................................................................................................... 68 Core Chronology ...................................................................................................... 69 VRS-inferred