The Importance of Host Fish in Long Range Transport of Unionids in Large Rivers
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The importance of host fish in long range transport of unionids in large rivers by Daelyn Adele Woolnough A dissertation submitted to the graduate faculty in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY Major: Ecology and Evolutionary Biology Program of Study Committee: John Downing, Co-major Professor Teresa Newton, Co-major Professor William Clark Sarah Nusser Clay Pierce Iowa State University Ames, Iowa 2006 Copyright © Daelyn Adele Woolnough, 2006. All rights reserved. UMI Number: 3229137 INFORMATION TO USERS The quality of this reproduction is dependent upon the quality of the copy submitted. Broken or indistinct print, colored or poor quality illustrations and photographs, print bleed-through, substandard margins, and improper alignment can adversely affect reproduction. In the unlikely event that the author did not send a complete manuscript and there are missing pages, these will be noted. Also, if unauthorized copyright material had to be removed, a note will indicate the deletion. UMI UMI Microform 3229137 Copyright 2006 by ProQuest Information and Learning Company. All rights reserved. This microform edition is protected against unauthorized copying under Title 17, United States Code. ProQuest Information and Learning Company 300 North Zeeb Road P.O. Box 1346 Ann Arbor, Ml 48106-1346 11 Graduate College Iowa State University This is to certify that the doctoral dissertation of Daelyn Adele Woolnough has met the dissertation requirements of Iowa State University Signature was redacted for privacy. Co jor Pr fessor Signature was redacted for privacy. Co-major Professor Signature was redacted for privacy. For the Major Program iii TABLE OF CONTENTS ACKNOWLEDGEMENTS v CHAPTER 1. GENERAL INTRODUCTION 1 Rationale 1 Research Objectives 2 Dissertation Organization 2 References 3 CHAPTER 2. FISH HOME RANGES DEPEND ON ECOSYSTEM SIZE AND SHAPE 5 Abstract 5 Introduction 5 Methods 7 Results 11 Discussion 12 Conclusion 16 Acknowledgements 17 References 17 Tables 23 Figure Legends 24 Figures 25 CHAPTER 3. SPATIAL PATTERNS OF FRESHWATER MUSSELS AND THEIR HOST FISH 28 Summary 28 Introduction 29 Methods 32 Results 35 Discussion 38 Acknowledgements 44 References 44 Table 53 Figure Legends 54 Figures 56 CHAPTER 4. CONNECTIVITY OF HOST FISH AMONG FRESHWATER MUSSEL COMMUNITIES 64 Abstract 64 Introduction 65 Methods 70 Results 76 Discussion 79 Conclusion 86 iv Acknowledgements 87 References 87 Tables 99 Figure Legends 102 Figures 105 CHAPTER 5. GENERAL CONCLUSIONS 112 General Conclusions 112 Future Research 113 References 115 APPENDIX A. Data from literature used in Chapter 2 117 APPENDIX B. Summary of freshwater mussels and host fish species found in a 38-km reach of the Upper Mississippi River (Navigational Pool 8) used in Chapter 3 141 APPENDIX C. Summary of freshwater mussels and known host fish species found in a 38-km reach of the Upper Mississippi River (Navigational Pool 8) used in Chapter 4 143 V ACKNOWLEDGEMENTS I would like to first thank my co-advisors Dr. John Downing (ISU) and Dr. Teresa Newton (USGS and ISU) for providing me with the opportunity to take on this project that considers questions about mussels that have always been asked but have never been considered prior to this study. I consider it a privilege to have two advisors; both of you have provided me with an outlook to ecological systems and inquiry that I never would have acquired had I not come to Iowa State University. You are both so passionate about your work and this passion has been contagious. Your combined knowledge about mussel-host systems as well as rivers and lakes is astonishing and your styles are complementary. John, your open door/open phone policy has been greatly appreciated throughout my time at Iowa State. Conversations about everything from ecological theory to teaching concepts will be held close to my heart throughout my career as an ecologist. You have definitely made me a "tougher" scientist; one of your goals if I remember correctly! Although you may have toughened me up I am appreciative of your understanding nature. Teresa, from your ability to always answer any questions I had fully and completely to providing me a bed in your home when I visited La Crosse you are always supportive. Prior to coming to Iowa State I felt I was quite detail oriented; I have learned to be even more detail oriented with your help. Your commitment to work on the Mississippi River is honourable and I look forward to collaborating with you in the future. To my committee members: Drs. William Clark, Sarah Nusser, and Clay Pierce, your input and push to make me think larger and about more concepts as well as helping me focus my dissertation work has improved this work substantially. From meeting with me to vi answering emails you have all been helpful by providing your expertise. I hope you have learned as much about the uniqueness of mussels as I have learned about your fields! Iowa State has a strong statistics program and I thank Dr. Nusser for encouraging me to investigate statistics opportunities at ISU. The Vertical Integration of Graduate Education group has taught me the many uses of spatial statistics available for using in whatever landscape question is being asked. Dr. Petruza Caragea was open to discussion even though she was not on my committee — thank you for your insight on predictive surfaces. For the staff and graduate students of the ISU Limnology Lab, you helped so much with your input and critiques of my presentations. You saved me from many more committee questions and prepared me for the ones I received. To Dale Tessin, Stephanie Koehler, Laura Erickson, Jessica Davis, and Jen Vogel thanks for the input and conversation. Thank you to the many other professors who have contributed to my education being truly multi- disciplinary. Also, to the USGS "Mussel Team" and Brian Ickes in La Crosse — you are a great team to work with. To the Iowa DNR in Bellevue and Emy Monroe thank you for allowing me to tag along for fish and mussel collection in the UMR. To Mom and Dad (Woolnough) and my future Mom and Dad (Zanatta) thank you for your ongoing support of my research and life decisions. You even came to visit Iowa while I was here; those trips were appreciated more than you will know. Dave, you were the first to teach me how to identify mussels and have since always supported my research. I am so grateful to have had your support for this past four years. Your love and commitment is what has allowed me to be more emotional about my work and helps to soften the edge of this "toughened" ecologist- thanks, xoxo. 1 CHAPTER 1. GENERAL INTRODUCTION Rationale Freshwater mussels (Family: Unionidae) are the most imperiled faunal group in North America (Richter et al., 1997), yet little is known about factors that influence their distribution in rivers and lakes—especially over large geographic areas (Strayer et al., 2004). They have a unique life cycle that includes an obligate parasite stage on fish. Some unionid species can complete their life cycle on one of several fish species (i.e., generalists), whereas other species require a specific species of fish to complete their life cycle (i.e., specialists). Movement by adults (tens of meters) can be upstream or downstream but there is an overall net downstream movement (Balfour & Smock, 1995; Villella et al., 2004). Therefore, adults have very restricted paths of dispersal. Throughout their >50 year life spans, consequently, any long range or upstream transport is principally accomplished during the parasitic stage (Bauer, 1992; Fuller, 1974). Of the 300 mussel species in North America, host fish have only been identified for roughly 120 species. This brief parasitic phase has lasting effects on adult mussel ecology—particularly in influencing the spatial patterns in their distribution which could be contributing to the decline of the unionid fauna. Prior research on resource requirements of unionids has traditionally been done on small spatial scales (e.g., river reaches of <100m) and relates mussel abundance to abiotic variables (Layzer & Madison, 1995; Strayer, 1993). The movement of host fish occurs on a larger scale (e.g., >100m) and both their distribution and abundance likely contribute to the spatial patterns of unionid communities. Many conservation strategies for unionids largely ignore the fish resource as well as the requirements for host survival. Lack of basic life history information, including the importance of host fish in structuring the spatial distribution of mussels, impedes the management and conservation of unionids. 2 Management of many species is currently based on incomplete understanding of population dynamics which includes demographics, reproductive success, and colonization patterns (Grouse et al., 1987). Conservation biologists have used metapopulation theory to support conservation corridors and increase the rate at which patches are recolonized by enhancing movement among populations (Hess, 1996). If the spatial distribution of fish is important in structuring the unionid community in large rivers, then concurrent management of both unionid and fish populations may be needed to sustain and restore declining unionid populations. According to metapopulation theory, patches with greater connectivity to others should have greater success than less connected patches. Research Objectives The goal of this dissertation is to determine the degree to which host fish could provide connectivity among mussel beds in the Upper Mississippi River based on metapopulation theory (Hanski & Gaggiotti, 2004) and to determine how this influences the success of patches of mussels. The objectives were to (1) estimate the home range of host fish to determine the potential movement of larval freshwater mussels; (2) use empirical data to predict the potential ecological consequence of host fish and freshwater mussel relations (e.g., persistence and spatial interactions); (3) quantify the degree of connectivity provided by host fish among mussel sites; and (4) quantify how connectivity contributes to mussel community condition.