THE DEVELOPMENT AND EVALUATION OF A FRESHWATER MUSSEL SAMPLING PROTOCOL FOR A LARGE LOWLAND RIVER by JASON RAY MEADOR Under the direction of James T. Peterson ABSTRACT Freshwater mussels are among the most imperiled aquatic species within the southeastern United States. Mangers are faced with the task gathering information via monitoring, and making decisions based on available information about local mussel populations. I gathered data on mussel behavior, demography, distribution, and detection to develop a cost-effective protocol for monitoring freshwater mussel populations within the Altamaha River. Surface abundance, survival, occupancy, and detection varied spatially, temporally, and among species. I then developed sampling stratum within mesohabitats based on empirical data and evaluated the efficacy of several sampling protocols via simulation. Spatial and temporal variation among species emphasize the importance for properly estimating and evaluating habitat based on use and detection and suggest refraining from raw count indices. INDEX WORDS: Altamaha River, Freshwater Mussels, Occupancy, Abundance, Estimation, Robust Design, Migration Patterns, Sample Design, Detection THE DEVELOPMENT AND EVALUATION OF A FRESHWATER MUSSEL SAMPLING PROTOCOL FOR A LARGE LOWLAND RIVER by JASON RAY MEADOR B.S., North Carolina State University, 2004 A Thesis Submitted to the Graduate Faculty of The University of Georgia in Partial Fulfillment of the Requirements for the Degree MASTER OF SCIENCE ATHENS, GEORGIA 2008 © 2008 Jason Ray Meador All Rights Reserved THE DEVELOPMENT AND EVALUATION OF A FRESHWATER MUSSEL SAMPLING PROTOCOL FOR A LARGE LOWLAND RIVER by JASON RAY MEADOR Major Professor: James T. Peterson Committee: Brett Albanese Michael J. Conroy Electronic Version Approved: Maureen Grasso Dean of the Graduate School The University of Georgia May 2008 ACKNOWLEDGEMENTS There are many people that offered assistance throughout the duration of this project for whom I am grateful. My major professor, Dr. James Peterson, was always willing to share insight, offer assistance, and clarification when I had questions. I also thank my committee members, Drs. Brett Albanese and Michael Conroy. Through their assistance and suggestions, they each brought a unique perspective to the project. I was privileged to work with a wonderful group of people who offered assistance in the field and provided insight and suggestions in the lab, all of which I consider my friends: Dr. Brett Albanese, Will Bickerstaff, Phillip Callihan, Casey Carpenter, Scott Craven, Matt Elliot, Abby Farrakesh, Becky Fauver, Loren Hunt, Mincy Moffett, Alison Price, Jill Olin, Sabrina Pankey, Colin Shea, Scott Small, Deb Weiler, Aaron Wilson, and Jason Wisniewski. I especially thank Jason Wisniewski for countless words of advice, encouragement, and field assistance including mussel identification. Now I can differentiate between shepardiania and shinola. This project would not have been possible without funding from the Georgia Department of Natural Resources. The Non-Game Section of Georgia Department of Natural Resources also provided necessary equipment such as boats and SCUBA gear for this project. Last, but surely not least, I want to thank my family and friends for their patience and encouragement prior to and throughout my pursuit of this degree. I especially thank my wife Kristen, for her unconditional love and support, and daughter Katie Anne, who was born during my pursuit of this degree and constantly reminds me to keep my priorities in order. iv TABLE OF CONTENTS Page ACKNOWLEDGEMENTS ………………………………………………………………...……iv CHAPTER 1 INTRODUCTION ………………………………………………………………………..1 2 OBJECTIVES …………………………………………………………………………….3 3 LITERATURE REVIEW …...............................................................................................4 Life History …………………………………………………………………………...4 Factors Influencing Mussel Distribution and Community Structure ……………...…7 Sampling Protocols ………………………………………………………………….10 4 METHODS ……………………………………………………………………………...13 Study Site …………………………………………………………………………….13 Demographic Parameters ……………………………………………………………...14 Sampling Procedure …………………………………………………………………16 Statistical Analysis …………………………………………………………………..18 Distribution and Detection …………………………………………………………….21 Sampling Procedure ……………………………………………………………...….23 Statistical Analysis …………………………………………………………………..24 Alternative Sampling Designs …………………………………………………………25 Alternative Population Decline ………………………………………………..…….27 Sample Design ……………………………………………………………...……….28 Statistical Analysis …………………………………………………………………..30 v 5 RESULTS …………………………………………………………………………...…..31 Demographic Parameters ………………………………………………………...……32 Distribution and Detection ………………………………………………………...…..36 Alternative Sampling Designs …………………………………………………………38 6 DISCUSSION ……………………………………………………………………….…..43 Mussel Demography and Behavior ………………………...……………………………43 Mussel Occupancy and Detection …………………………….………………..………..50 Suggested Sample Designs ………….……………………………………...……………57 LITERATURE CITED ……………………………………………………………….…………61 APPENDIX A ………………………………………………………………………………….114 APPENDIX B ………………………………………………………………………………….116 APPENDIX C ………………………………………………………………………………….132 vi CHAPTER 1 INTRODUCTION Freshwater mussels [Family Unionidae] are a crucial component of aquatic ecosystems. Being primary consumers, they are considered important keystone species serving as a food source for specific mammalian, avian, and fish species (Parmalee and Bogan 1998). Furthermore, mussels can be useful biotic indicators due to their sensitivity to anthropogenic degradations, such as point and non-point source pollution, and sedimentation (Neves et al. 1997). However, mussel reproduction requires species-specific host-fishes (Hoggarth 1992) that can cause them to be sensitive to factors that also affect their hosts. Consequently, anthropogenic disruptions that affect mussel hosts have caused the decline of many freshwater mussel populations within the southeastern United States (Neves et al. 1997). Since enactment of the Endangered Species Act (ESA) in 1973, 27% of the 297 known mussels species within the United States have been listed as endangered, threatened, or extinct, with an additional 43% identified as species of special concern (i.e. low densities, restricted distribution) but not federally protected (Vaughn and Taylor 1999). The southeast United States contains the highest diversity of mussel fauna in North America, with 91% of the known species occurring in Alabama, Arkansas, Florida, Georgia, Kentucky, Louisiana, Mississippi, North Carolina, South Carolina, Tennessee, and Virginia (Turgeon et al. 1988; Neves et al. 1997). Currently, 75% of those species are believed to be in decline (Neves et al. 1997). This includes over half (66%) of Georgia’s approximately 122 native freshwater mussel species being either 1 state or federally listed or considered extirpated from the state; of these species 12 are considered globally extinct (Paul Johnson, Alabama Department of Conservation and Natural Resources, personal communication). Three of these imperiled mussels are found in the Altamaha River, a large coastal river in Georgia. The Altamaha spinymussel (Elliptio spinosa; Lea 1836) is listed by the state of Georgia as endangered and recognized as a candidate for federal listing under the U.S. ESA. The Savannah lilliput (Toxolasma pullus; Conrad 1838) is classified as a federal species of concern because of its global rarity and is considered critically imperiled in Georgia whereas the Altamaha arcmussel (Alasmidonta arcula; Lea 1838) is listed as state threatened (GADNR). The conservation and restoration of mussel fauna requires the development of efficient and effective management plans. To be effective, planners need information on the current status and distribution of mussel populations combined with a means to evaluate the effectiveness of management actions. Such information is particularly difficult to collect in large rivers, such as the Altamaha River, where flow, depth, and visibility restrict the use of common and cost-effective sampling methods, such as wading and snorkeling. Currently, there is no sampling protocol for estimating the status and distribution of mussel populations in large riverine ecosystems. Therefore, the purpose of this study was to develop and evaluate different sample designs for estimating the status and distribution of mussels in large rivers. 2 CHAPTER 2 OBJECTIVES The ultimate goal was to develop a cost-effective sampling protocol for monitoring the distribution and status of freshwater mussels within the Altamaha River. Therefore, I developed and evaluated various techniques for sampling mussel assemblages in the Altamaha River with the following objectives: 1) Develop sampling stratum for the Altamaha River with respect to mussel distributions based upon species-specific habitat selection. 2) Develop sampling designs for estimating the distribution and status (e.g., abundance, and density) of mussel populations. 3) Evaluate the relative effort and effectiveness of the different sampling protocols using a combination of data and model simulation. 3 CHAPTER 3 LITERATURE REVIEW The development of effective and cost-efficient sampling protocols requires an understanding of the biology of freshwater mussels. For example, mussels move vertically within the river bed such that only a portion of mussel populations are near the surface and vulnerable to capture (Amyot and Downing 1997). The vertical movement can be related