An investigation into the taxonomy, distribution, seasonality and phenology of Laminariaceae (Phaeophyceae) in Atlantic Canada by Caroline Longtin BSc University of Victoria, 2006 MSc St. Francis Xavier University, 2008 A Dissertation Submitted in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy in the Graduate Academic Unit of Biology Supervisor: Gary W. Saunders, PhD, Biology Examining Board: Antony Diamond, PhD, Faculty of Forestry and Environmental Management (Chair) Donald Baird, PhD, Department of Biology Stephen Heard, PhD, Department of Biology External Examiner: Arthur Mathieson, PhD, Department of Biology, University of New Hampshire This dissertation is accepted by the Dean of Graduate Studies THE UNIVERSITY OF NEW BRUNSWICK August, 2014 ©Caroline Longtin, 2014 ABSTRACT The Laminariaceae is one of eight families in the order Laminariales (the kelps) and most members occur in the northern hemisphere. A recent molecular study in Atlantic Canada confirmed the presence of Laminaria digitata, Saccharina latissima and a third genetic species, which was later attributed to S. groenlandica. This third genetic species was likely overlooked in this region due to its morphological similarity to L. digitata and S. latissima. The main objective of this thesis was to investigate the taxonomy, distribution and seasonality of the Laminariaceae in Atlantic Canada and verify the taxonomic identity of the North American genetic species attributed to S. groenlandica. First, I clarified the taxonomic confusion surrounding the North American genetic species attributed to S. groenlandica. I determined that the North American genetic species currently attributed to S. groenlandica is correctly attributed to L. nigripes; therefore, Saccharina nigripes (J. Agardh) C. Longtin et G.W. Saunders comb. nov. was established and includes North American collections previously attributed to S. groenlandica. Second, I utilized molecular tools to determine the relative abundances of L. digitata, S. nigripes and S. latissima in differing habitats in the Bay of Fundy intertidal zone. I determined that the digitate morphology of S. nigripes can be the major contributor to Laminariaceae community structure at moderate and wave-exposed sites in the Bay of Fundy; however, its abundance fluctuates depending on the year. Third, I attempted to clarify the seasonality and phenology of the Laminariaceae in the Maritime Provinces. Due to the morphological similarity of S. nigripes to L. digitata and S. latissima previous literature on the seasonality and phenology of S. latissima and L. digitata may have inadvertently included S. nigripes. 11 Saccharina nigripes was rare at the study site in the year this study was performed and I was unable to determine its seasonality and phenology. However, I did determine that the seasonality and phenology of L. digitata and S. latissima in this region are consistent with previous reports in Atlantic Canada, and the presence of S. nigripes is unlikely to impact previous literature on the seasonality and phenology of L. digitata and S. latissima. 111 DEDICATION This thesis is dedicated to my parents, Paul and Lorraine, for their continuous love and support. IV ACKNOWLEDGEMENTS I would like to thank the many people who have made this thesis possible and have provided support throughout this journey. First, I would like to thank my supervisor, Dr. Gary Saunders for his assistance and guidance throughout this degree. I'm sure at times it was a struggle to explain basic molecular biology to a field ecologist, but it was a very rewarding learning experience for myself. I am also grateful for the opportunities that I have received in the Saunders Lab. In the past five years I have traveled the New England coast, performed fieldwork in Bamfield, visited herbaria in Denmark and Sweden, and had the chance to attend various Phycological and Ecological conferences. I would also like to thank Dr. Garbary for his continuous support of my Phycological career. I met Dr. Garbary when he was a committee member for my MSc thesis. Since that time he has become a great mentor and friend and I look forward to collaborating on future publications. Many thanks to all the members of the Saunders Lab, past and present, who have provided field, lab and emotional support (including countless nights at the Grad House) throughout the past five years. Thank you all for making this such an enjoyable experience. Thank you to: Meghann Bruce, Dr. Bridgette Clarkston, Dr. Susan Clayden, Dr. Kyatt Dixon, Gina Filloramo, Dr. Sarah Hamsher, Dr. Katy Hind, Dr. Chris Jackson, Dr. Hana Kucera, Lesleigh Kraft, Dr. Dan McDevit, Tanya Moore, and Amanda Savoie. I would also like to thank my committee members, Dr. Jason Addison and Dr. Myriam Barbeau for their guidance over the past few years and helpful comments on this thesis. V Finally, I would like to thank my family for their continuous support of my academic endeavors. I would not have been able to pursue my dream of becoming a marine biologist without the support of my parents, Lorraine and Paul, my sister Stephanie and my aunt Christine. I would also like to thank my partner Bill Goodine, for all of his support and patience throughout this process. Thank you for listening to countless presentations on kelp ecology and for enthusiastically providing field assistance, even in the middle of winter. I would also like to thank Bill and Rose Anne Goodine for their support and for accepting me as a part of their family. You have really made New Brunswick feel like home. Thank you! Vl Table of Contents ABSTRACT ........................................................................................................................ ii DEDICATION ................................................................................................................... iv ACKNOWLEDGEMENTS ................................................................................................ V Table of Contents .............................................................................................................. vii List of Tables ...................................................................................................................... x List of Figures .................................................................................................................. xiii Chapter 1. General introduction .......................................................................................... 1 Kelp ecology ................................................................................................................. 2 Kelp taxonomy and distribution .................................................................................... 3 Kelp morphology .......................................................................................................... 3 Kelp life history ............................................................................................................ 4 Kelp recruitment and colonization ................................................................................ 5 Morphological variation in kelp .................................................................................... 7 Kelp taxonomy and phylogenetic relationships ............................................................ 8 Thesis objectives ........................................................................................................... 9 Statement of contributions to research and writing .................................................... 13 References ................................................................................................................... 14 Chapter 2. On the utility of mucilage ducts as a taxonomic character in Laminaria and Saccharina - the conundrum of S. groenlandica .............................................................. 24 Abstract ....................................................................................................................... 25 Introduction ................................................................................................................. 26 Methods ....................................................................................................................... 29 vii Results ......................................................................................................................... 31 Discussion ................................................................................................................... 36 Acknowledgements ..................................................................................................... 42 References ................................................................................................................... 43 Chapter 3. An investigation on the impact of the overlooked species Saccharina nigripes on knowledge of the reported kelp Laminaria digitata and Saccharina latissima {Laminariales, Phaeophyceae) in the Bay of Fundy ......................................................... 54 Abstract ....................................................................................................................... 5 5 Introduction ................................................................................................................. 56 Methods ....................................................................................................................... 60 Results ........................................................................................................................