ECOLOGICAL INTERACTIONS AND GEOLOGICAL IMPLICATIONS OF FORAMINIFERA AND ASSOCIATED MEIOFAUNA IN TEMPERATE SALT MARSHES OF EASTERN CANADA by Jennifer Lena Frail-Gauthier Submitted in partial fulfilment of the requirements for the degree of Doctor of Philosophy at Dalhousie University Halifax, Nova Scotia January, 2018 © Copyright by Jennifer Lena Frail-Gauthier, 2018 This is for you, Dave. Without you, I would have never discovered the treasures in the mud. ii TABLE OF CONTENTS List of Tables......................................................................................................................x List of Figures..................................................................................................................xii Abstract.............................................................................................................................xv List of Abbreviations and Symbols Used .....................................................................xvi Acknowledgements…………………………………..….………………………...…..xvii Chapter 1: Introduction…………………………………………………………………1 1.1 General Introduction .....................................................................................................1 1.2 Study Location and Evolution of Thesis........................................................................8 1.3 Chapter Outlines and Objectives.................................................................................11 1.3.1 Chapter 2: Development of a Salt Marsh Mesocosm to Study Spatio-Temporal Dynamics of Benthic Foraminifera............................................11 1.3.2 Chapter 3: Taxonomic Resolution and Tidal Gradients in Food Webs for Two Temperate Salt Marshes: How Much Detail is Enough?...............13 1.3.3 Chapter 4: Use of δ13C and δ15N Stable Isotopes Within and Between Two Temperate Salt Marshes in Atlantic Canada to Examine Patterns of Food Web Structure and Function......................................................14 1.3.4 Chapter 5: Mesocosm and Microcosm Experiments on the Feeding of Temperate Salt Marsh Foraminifera...................................................16 1.3.5 Chapter 6: Conclusions.................................................................................17 1.4 Overview ........……………………………………………………………………….17 Chapter 2: Development of a Salt Marsh Mesocosm to Study Spatio- Temporal Dynamics of Benthic Foraminifera ……………………….………………19 2.0 Abstract ……………………………………………………………………………...19 2.1 Introduction ………………………………………………………….………………20 iii 2.1.1 Salt Marsh Laboratory Mesocosms …………………………….…………20 2.1.2 Salt Marsh Foraminifera ..............................................................................21 2.1.3 Objectives ....................................................................................................21 2.2 Study Area and Mesocosm .........................................................................................22 2.3 Methods .......................................................................................................................24 2.3.1 Field Sampling for Mesocosm Development ..............................................24 2.3.2 Mesocosm Preparation .................................................................................26 Laboratory Marsh Design .........................................................................26 Tidal Simulation and Fresh Water Input ...................................................27 Ultraviolet Light ........................................................................................27 Temperature and Salinity ..........................................................................28 2.3.3 Sediment Sampling ......................................................................................28 2.3.4 Sample Examination ....................................................................................30 2.3.5 Field to Mesocosm Comparison ..................................................................30 2.3.6 Data Analysis ...............................................................................................32 2.4 Results .........................................................................................................................32 2.4.1 Salinity Comparisons ...................................................................................35 2.4.2 Seasonality in Foraminifera .........................................................................39 2.4.3. Zonal Differences for Foraminifera: Mesocosm vs. Field ..........................43 2.4.4 Key Results ..................................................................................................50 2.5 Discussion ...................................................................................................................52 2.5.1 Comparison to Other Salt Marsh Mesocosms .............................................52 2.5.2 Field Versus Mesocosm Foraminiferal Comparisons and Implications ....................................................................................................56 iv 2.5.3 Foraminiferal Zonation ................................................................................60 2.5.4 Value of Laboratory Salt Marsh Mesocosms and Future Work ..................62 2.5.5 Biological and Ecological Analysis of Mesocosm Foraminifera ................63 2.6 Conclusions .................................................................................................................65 Chapter 3: Taxonomic Resolution and Tidal Gradients in Food Webs for Two Temperate Salt Marshes: How Much Detail is Enough? .............................67 3.0 Abstract .......................................................................................................................68 3.1 Introduction .................................................................................................................69 3.1.1 Objectives ....................................................................................................71 3.2 Study Area: Windsor and Chezzetcook Marshes ........................................................72 3.3 Methods .......................................................................................................................78 3.3.1 Sample Collection and Examination ............................................................78 3.3.2 Food-Web Construction ...............................................................................79 3.3.3 Food-Web Properties ...................................................................................81 3.3.4 Statistical Analysis .......................................................................................84 3.4 Results .........................................................................................................................85 3.4.1 High-, Medium- and Low-Resolution Food Webs ......................................85 3.4.2 Comparison of High-Resolution Food Webs Between Salt Marshes and Zones ........................................................................................94 3.4.3 Niche Model .................................................................................................99 3.5 Discussion ................................................................................................................103 3.5.1 Taxonomic Resolution ...............................................................................103 3.5.2 Chezzetcook and Windsor Metawebs ........................................................109 v 3.5.3 Tidal Gradients ...........................................................................................110 3.5.4 Comparison with Other Food Webs ..........................................................112 3.5.5 Implications for Conservation ....................................................................117 3.6 Conclusions ...............................................................................................................120 Chapter 4: Use of δ13Carbon and δ15Nitrogen Stable Isotopes Within and Between Two Temperate Salt Marshes, Atlantic Canada, to Examine Patterns of Food Web Structure and Function...........................................122 4.0 Abstract .....................................................................................................................122 4.1 Introduction ...............................................................................................................123 4.2 Study Areas: Nova Scotia Marshes ...........................................................................126 4.3 Field and Laboratory Methods ..................................................................................128 4.3.1 Sample Collection and Preparation ............................................................128 4.3.2 Stable Isotope Analysis ..............................................................................129 4.3.3 Data Analysis .............................................................................................131 4.4 Results .......................................................................................................................133 4.4.1 Overall Patterns of δ13C, δ15N and C:N Within and Between Marsh Sites ...........................................................................................139 4.4.2 Isotopic Composition of Sources ...............................................................147 4.4.3 Isotopic Composition of Consumers ..........................................................150