Invasion dynamics of the round goby {Neogobius meianostomus) in the Trent-Severn Waterway A Thesis Submitted to the Committee on Graduate Studies in Partial Fulfillment of the Requirements for the Degree of Master of Science in the Faculty of Arts and Science TRENT UNIVERSITY Peterborough, Ontario, Canada © Copyright by Jake Brownscombe 2011 Environmental and Life Sciences M.Sc. 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The author retains copyright L'auteur conserve la propriete du droit d'auteur ownership and moral rights in this et des droits moraux qui protege cette these. Ni thesis. Neither the thesis nor la these ni des extraits substantiels de celle-ci substantial extracts from it may be ne doivent etre imprimes ou autrement printed or otherwise reproduced reproduits sans son autorisation. without the author's permission. In compliance with the Canadian Conformement a la loi canadienne sur la Privacy Act some supporting forms protection de la vie privee, quelques may have been removed from this formulaires secondaires ont ete enleves de thesis. cette these. While these forms may be included Bien que ces formulaires aient inclus dans in the document page count, their la pagination, il n'y aura aucun contenu removal does not represent any loss manquant. of content from the thesis. 1+1 Canada ABSTRACT Invasion dynamics of the round goby (Neogobius meianostomus) in the Trent-Severn Waterway Jake Brownscombe I studied the invasion dynamics of the round goby (Neogobius meianostomus) in the Trent-Severn Waterway, southeastern Ontario, Canada in 2009 and 2010. The angling removal method was used to sample the pioneering upstream and downstream edges of their range in addition to a longer established area. Edge sites increased drastically in site occupancy, abundance, and goby size over the first summer of occupation. The most rapid upstream expansion occurred during the non-reproductive season (9.1 km). Individuals sampled in their expanded range were small and female biased relative to other range locations. A dispersal model predicts that a detectable round goby population may travel as fast as 9.8 km/year upstream through the Waterway. Tethering experiments indicate that round goby predation rates are lower in a recently invaded area of the Trent River than a longer established area, which suggests that round gobies experience low predation risk during initial stages of invasion. Keywords: colonization, demographics, diffusion model, dispersal, habitat, invasion dynamics, predation, range expansion, tethering li Acknowledgements I would like to extend my gratitude to everyone who provided me with assistance and guidance during my thesis work. To my supervisor, Michael Fox, who has helped me improve as a scientific researcher and writer. Thanks to my supervisory committee, Dave Beresford and Don Mackay for your help with the modeling portion of my thesis. To Lee Gutowsky, for orienting me in the field and helping develop my sampling regime. To my field assistants, Olivia Puckrin, Anna Rooke, Greg Meisner, and Emily Fobert, for helping during long days of sampling. I also extend my gratitude to my girlfriend, Caitlin Higginson, and my entire family for support. Thanks to Chris Williams and Scott Reid for providing me with fish community data. Also to the Hastings Village Marina, and all the private land owners that allowed us access to sampling sites, and to conduct tethering experiments in the Trent River in front of their property. Finally, thanks to NSERC for providing funding for this project. iii Table of contents page ABSTRACT ii Acknowledgments iii List of figures vi List of tables ix Chapter 1: General Introduction 1 Chapter 2: Range expansion, population dynamics, demographics, and habitat use of the round goby (Neogobius meianostomus) in the Trent-Severn Waterway 7 INTRODUCTION 7 METHODS 10 Study location 10 Site selection 13 Sampling 14 Data analysis 15 RESULTS 17 Site occupancy and range expansion 17 Abundance (CPUE) 20 Length distribution 25 Sex ratios 28 Upstream dispersers 28 Habitat 31 DISCUSSION 33 Chapter 3: A diffusion model for upstream dispersal of the round goby in the Trent-Severn Waterway 51 INTRODUCTION 51 METHODS 54 Study area 54 iv Data collection 54 Model 55 RESULTS 58 DISCUSSION 64 Chapter 4: Predation rates of round goby in established and recently invaded areas of the Trent River 69 INTRODUCTION 69 METHODS 72 Study location 72 Site selection 72 Tethering experiment 74 Data analysis 77 RESULTS 78 Predation loss 78 Round goby predators 85 DISCUSSION 85 Chapter 5: General Discussion 98 Future work 102 References 106 Appendix A: Statistical analysis 128 Appendix B: Sample sizes 136 v List of figures page Figure 1: Sampling sites for round gobies at the center and edges of their range in the Trent-Severn Waterway in May and August of 2009 and 2010 12 Figure 2: Round goby relative abundance (catch/m2) at center of range sites (25) near the point of introduction in the Trent River, sampled using the angling removal method; May and August of 2009 and 2010. For location refer to Figure 1 18 Figure 3: Round goby relative abundance (catch per m2) at sites across the upstream edge of their distribution in the Trent-Severn Waterway in May and August of 2009 and 2010. Star denotes the upstream edge. For location refer to Figure 1 19 Figure 4: Round goby relative abundance (catch per m2) at sites across the downstream edge of their distribution in the Trent-Severn Waterway in May and August of 2010. For location refer to Figure 1 21 Figure 5: Presence/absence (A) and relative abundance (catch per m2) (B) of round gobies at DSE with additional sites extending to the Bay of Quinte in May 2010 sampled using the angling removal method. For scale and location refer to Figure 1 22 Figure 6: Mean round goby catch (per m2) excluding non-catch sites, using the angling removal technique at sites in the upstream edge (USE), center of range (CORE), and downstream edge (DSE) range locations in the Trent-Severn Waterway; May and August 2009 and 2010 (+ SE) 23 Figure 7: Mean total length (mm) of round gobies sampled using the angling removal technique at center of range (CORE), upstream edge (USE), and downstream edge (DSE) range locations in the Trent-Severn Waterway; May and August 2009 and 2010 (±SE) 26 Figure 8: Length frequency distribution of round gobies in Center of range (CORE), upstream edge (USE), and downstream edge (DSE) sampling sites in the Trent-Severn Waterway; May and August 2009 and 2010 27 Figure 9: Round goby sex ratio in angling sites in CORE, USE, and DSE range locations in the Trent-Severn Waterway; May and August 2009 and 2010 (± SE) 29 Figure 10: The Mean percentage of males and total length (TL) of round gobies in sites at CORE, USE, DSE, Prior USE in 2010 (occupied 2009) vi and Expanded USE 2010 (beyond edge of range in 2009) range locations; May and August 2009 and 2010 (± SE) 30 Figure 11: Occupancy of round gobies in proportions of rock habitat at upstream edge (USE), center of range (CORE), and downstream edge (DSE) range locations in the Trent-Severn Waterway; May and August 2009 and 2010 (± SE) 32 Figure 12: Mean relative abundance (catch/m2, in catch sites) of round gobies in five habitat types (boulder, cobble, gravel, sand, mud) at upstream edge (USE), center of range (CORE), and downstream edge (DSE) range locations in the Trent-Severn Waterway; May and August 2009 and 2010 (+ SE) 34 Figure 13: Probability distribution of the gamma function with varying combinations of a and 3 parameters 57 Figure 14: Estimated transit times (months/km) of round gobies from arrival at sites upstream from their edge of range in May 2009. Gamma parameters are a=1.08, p=1.67 60 Figure 15: Mean predicted arrival times (upper and lower 95% confidence limits) of detectable round gobies at locations upstream from their distribution in the Trent-Severn Waterway in May 2009 using a gamma transit time model 61 Figure 16: Probability of upstream movement of round gobies (km/year) from observed range expansion in the Trent-Severn Waterway from May 2009 to August 2010. Black hatched line represents 5 % probability 62 Figure 17: Probability of upstream movement of round gobies (km/year) from upstream model (P=1.67, solid grey line), and a hypothetical downstream model (P=0.84, hatched grey line). Black hatched line represents 5 % probability 63 Figure 18: round goby tethering sites in three habitat types: sandy shoal (SS), shallow rocky shoal (SRS), and a deep rocky shoal at CORE and