Paleolimnological Investigation of Gilmour Bay, Chandos ... ... This study uses paleolimnology to...

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  • Paleolimnological Investigation of Gilmour Bay, Chandos Lake, Ontario:

    FINAL REPORT January 2019

    Prepared for: Chandos Lake Property Owners Association (CLPOA) By: Katrina A. Moser, Associate Professor, Dept. of Geography, The University of Western Ontario

    Assisted By: Ms. Kelly Hollingshead, MSc. And Mr. Soomin Lee January 2019

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    ACKNOWLEDGEMENTS In 2014 Ms. Kelly Hollingshead and Mr. Geoff and Mrs. Penny Anderson collected the sediment cores used in this study. Ms. Hollinghead’s previous report (Hollingshead, 2017) set the stage for the research presented in this report. Mr. Soomin Lee completed his B.Sc. Honours thesis in the Environmental Science Program at Western University. For his thesis and under my supervision he determined the chlorophyll a and biogenic silica measurements presented in this report. The diatom identifications and analyses were done by Dr. Katrina Moser. We thank Prof. John P. Smol for allowing us access to facilities to measure chlorophyll a at the Paleoecological Environmental Assessment and Research Laboratory (PEARL) at Queen’s University in Kingston, Ontario. We are grateful to MyCore Scientific Inc., and particularly Jan Lardner and Linda Kimpe, who ensured the completion of 210Pb dating. Special thanks to Mr. Geoff Anderson and Mrs. Penny Anderson for their help in collecting the sediment cores, and their continued support and kind hospitality during both projects.

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    TABLE OF CONTENTS ACKNOWLEDGEMENTS.......................................................................................................................2

    EXECUTIVE SUMMARY ......................................................................................................................5

    GLOSSARY.........................................................................................................................................7

    INTRODUCTION..................................................................................................................................8

    STUDY AREA .....................................................................................................................................9

    METHODS ........................................................................................................................................11

    Historical and Climate Data...................................................................................................................11

    Sediment Core Collection and Extrusion..............................................................................................1 1

    210Pb Chronology................ ...................................................................................................................13

    Chlorophyll a (Overall Algal Production)................................................................................................14

    Biogenic Silica (Diatom Production)......................................................................................................14

    Diatom Sample Preparation and Analysis.............................................................................................. 15

    Data Analysis and Presentation .............................................................................................................15

    RESULTS ...........................................................................................................................................15

    The History of Chandos Lake ................................................................................................................ 15

    Climate Data and Trends........................................................................................................................ 16

    Core Description and Chronology .......................................................................................................... 18

    Chlorophyll a (Overall Algal Production) and Biogenic Silica (Diatom Production)................................18

    Diatoms ......................... .........................................................................................................................20

    DISCUSSION ......................................................................................................................................22

    The Effects of Land Use and Climate Change on Chandos Lake............................................................. .22

    Recommendations to Protect Gilmour Bay and Chandos Lake (Coming Soon).................................... 25

    CONCLUSION........................................... ..........................................................................................26

    REFERENCES .....................................................................................................................................27

    List of Figures Figure 1: Aerial view of Chandos Lake ....................................................................................................... 10 Figure 2: The bathymetry of Gilmour Bay...................................................................................................10 Figure 3: General operation of a messenger-triggered gravity corer .........................................................12 Figure 4: Photographs of Chandos Lake cores ............................................................................................12 Figure 5: Sediment core in extruder ready for sectioning in the field ........................................................13 Figure 6: Climate Data..................................................................................................................................17 Figure 7: The 210Pb Chronology................................................................................................................18 Figure 8: Chlorophyll a and Biogenic Silica and Land Use...........................................................................19 Figure 9: Chlorophyll a and Biogenic Silica and Temperature ...................................................................20

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    Figure 10: Diatom Stratigraphy..................................................................................................................21 Figure 11: All data summarized..................................................................................................................23 Figure 12: Total phosphorus overtime at Gilmour Bay...............................................................................25 List of Tables Table 1: Lake and watershed properties of Chandos Lake. ........................................................................ 9 Table 2: Limnological characteristics ... ......................................................................................................11 Table 3: Core Depths........................ ..........................................................................................................13 Table 4: Historical Periods ..........................................................................................................................16

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    EXECUTIVE SUMMARY

    Land use changes and human-caused climate warming potentially degrade the water quality of lakes. This study uses paleolimnology to determine whether the water quality of Gilmour Bay, Chandos Lake, Ontario, has changed since European settlement to present day, particularly considering the effects of changing land use and warming temperatures. Land use changes, including land clearance for lumber and settlement, as well as expanding development and associated septic systems, can increase the amount of nutrients transported and delivered from the land to the lake. Increased nutrient concentrations in lakes can lead to an increase in algal production. These changes are referred to as eutrophication, and can result in a loss of recreation, changes in taste and odour of waters, oxygen depletion, and fish kills. Warming temperatures are another factor that has been shown to increase algal production and reduce water quality, but the mechanisms linking warming and algal production are complex. This research uses sedimentary chlorophyll a and biogenic silica as indicators of overall algal and diatom production, respectively. Diatoms are one type of algae that are often a major component of primary production in lakes. Changes in diatom community composition were used to determine and track changes in water quality in Gilmour Bay. The results show that Gilmour Bay has changed markedly in the last 175 years and particularly in the last 30 years. The records presented here show that the Gilmour Bay ecosystem response to a combination of environmental stressors is complex, and disentangling the response to individual stressors is difficult. What is clear from our research is that the Gilmour Bay ecosystem is sensitive to both landscape changes and warming temperatures. Four main periods of change were determined based on changes in diatom community composition. The first period spans from 1850 to 1913, which is coincident with a period of land clearance. Logging would have peaked in the late 1800s, and surveys show that much of the forests had been removed by 1913. This period is also characterized by gradually warming temperatures and earlier ice out dates. Diatom community composition indicates that thermal stratification in Gilmour Bay during this time was relatively strong and nutrient concent