BENTHIC COMMUNITY STRUCTURE RESPONSE TO FLOW DYNAMICS IN TROPICAL ISLAND AND TEMPERATE CONTINENTAL STREAMS Dissertation Submitted to The College of Arts and Sciences of the UNIVERSITY OF DAYTON In Partial Fulfillment of the Requirements for The Degree Doctor of Philosophy in Biology By Kathleen R. Gorbach, M.S. UNIVERSITY OF DAYTON Dayton, Ohio December, 2012 BENTHIC COMMUNITY STRUCTURE RESPONSE TO FLOW DYNAMICS IN TROPICAL ISLAND AND TEMPERATE CONTINENTAL STREAMS Name: Gorbach, Kathleen R. APPROVED BY: __________________________ __________________________ Albert J. Burky, Ph.D. M. Eric Benbow, Ph.D. Faculty Advisor Faculty Advisor __________________________ __________________________ Karolyn Hansen, Ph.D. Mollie D. McIntosh, Ph.D. Graduate Committee Member Graduate Committee Member __________________________ __________________________ Mark Nielsen, Ph.D. P. Kelly Williams, Ph.D. Graduate Committee Member Graduate Committee Member ! ! ii! © Copyright by Kathleen R. Gorbach All rights reserved 2012 ! iii! ABSTRACT BENTHIC COMMUNITY STRUCTURE RESPONSE TO FLOW DYNAMICS IN TROPICAL ISLAND AND TEMPERATE CONTINENTAL STREAMS Name: Gorbach, Kathleen R. University of Dayton Advisors: Drs. Albert J. Burky & M. Eric Benbow Hydraulic characteristics in lotic ecosystems are influential in the structure and function of aquatic benthic communities. Human activities and the increased demand for freshwater have caused the modification of natural flow regimes worldwide. Hydrological alterations, such as dams, diversions, and channelizations, are associated with ecological change and known to have detrimental effects on benthic communities. As a whole, this dissertation investigated the effects of hydraulic variables on the spatial distribution of macroinvertebrates and habitat template characteristics in tropical and temperate freshwater streams of the West Maui Mountains, Maui, Hawaii, and in Dayton, Ohio. The first two studies took place in Hawaiian mountain streams that have been diverted, often removing >95% of base flow, for development, agriculture and tourism, thus modifying the natural flow and altering habitat and species composition. A transplant study investigated the effects of water removal and increased density on ! iv! dispersal and upstream migration of N. granosa. Initial mean upstream migration rate was 0.25, 0.66 and 1.16 m/d under reduced flow, natural flow and natural flow with increased snail density, respectively. Through calculations using rates from published studies of neritids migrating en masse or in long lines, we generated realistic time frames for N. granosa to migrate above diversions, ranging from 72 days to 2.5 years (aggregate) and 29 days to 1.1 years (long narrow line). By understanding upstream migration, recommendations for migratory pathway and population restoration can be applied globally for tropical amphidromous species. Secondly, habitat template, discharge, habitat flow, and macroinvertebrate insect indices were evaluated within riffle and cascade microhabitats upstream and downstream of the highest elevation diversion in four streams of the West Maui Mountains. A significant 44% reduction in macroinvertebrate density downstream of diversions was found when streams and sites were pooled (p = 0.0009, df = 1, F = 11.49). Microhabitat had a significant effect on the ratio of native to introduced taxa densities, with the amphibious splash zone home to significantly more endemic taxa compared to riffles. Non-native taxa were dominant (> 95% by density) and ubiquitous in riffle habitats. Our findings contribute to ongoing water management and restoration efforts focused on the conservation of native species and habitat integrity in tropical streams worldwide. Finally, in the Little Miami River, Ohio, the physical template and macroinvertebrate community were compared between riffle and run habitats. Mean flow velocity and macroinvertebrate densities were significantly greater in riffle (Flow: mean ± SE = 0.74 ± 0.04 m/s; Density: 1892 ± 200.2) than run (Flow: 0.32 ± 0.01 m/s; Density: 540.3 ± 76.8) habitats. Linear regression found a positive and significant ! v! relationship (y = 4097x – 115.1, p < 0.0001) where 49% of variation in macroinvertebrate density was explained by mid-column velocity. Our results call for the need of future analyses using simple and complex hydraulic variables to accurately predict the distribution of invertebrate communities. In conclusion, comprehensive understanding of how flow variation affects stream ecosystems is necessary for the development of future management practices that promote balance between economic and environmental benefits. ! vi! Dedicated to my parents, Fred and Anne Jennings, who have encouraged me to seize every opportunity, supporting me with excitement and enthusiasm, and showering me with unconditional love. ! vii! ACKNOWLEDGMENTS I have had the pleasure of interacting with wonderful people throughout this doctoral graduate program, each impacting my life in a profound way. It’s amazing where life takes you, and I’m fortunate to have had this wonderful experience. Family, friends and colleagues have made it all possible, contributing immensely to this final product. Whether it was support at home, another warm body in the field, hours spent picking bugs at the microscope, or good laughs to ease the frustration; my relationships with others have made this achievable. I am deeply grateful to my two advisors, Drs. Albert Burky and Eric Benbow. They have shown me the world, taught me invaluable life lessons, dedicated hours and hours to me – talking, teaching and helping me better my critical thinking and writing skills, all the while developing a friendship that will always be true. You are two of the most outstanding and important men in my life. Thank you to my Graduate Advisory Committee – Drs. Carl Friese, Karolyn Hansen, Mark Nielson, Mollie McIntosh, and Kelly Williams. I appreciate the continued guidance and time they gave to developing me as a contributing scientist. I would also like to express thanks to the University of Dayton Graduate School and Biology Department for their financial assistance, providing teaching and travel opportunities, and maintaining a successful graduate program. Going through it together, I’d like to thank my fellow graduate students who provided much camaraderie – especially Casey Hanley, Andy Lewis, Rachel Barker, Jen ! viii! Lang, Tracy Collins, and Elizabeth Rhodes. A special and sincere thanks to my sidekick, partner in crime and friend through it all, Megan Shoda. Her positivity, intellectual insights, brute strength, and smiles made all the difference. The endless hours together – in the stream, at home, driving the stream mobile, and of course in the lab sitting around our microscopes, were more than enjoyable. Fortunate for me, she saved me from wild dogs and bioluminescent algae scam artists, and the GIS expertise she provided has always been top notch. My fieldwork and the laboratory aftermath would not have been humanly possible without the help of numerous undergraduates. Thank you to Doug Vonderhaar, Tiffany Blair, Jon White, Carolyn Teter, Maggie Ernst, Ryan Lemier, Ryan Andrews, Allison Gansel, Ian Barron, Gustavo Diaz, Elise Grotehouse, Jack Farrely, Jessica Teater, Charlotte Perko, John Kurzawa, Liz Grazdick, and Melanie Aldaharian. I am grateful for the time and effort they put into my work. Their extra hands and eyes, and more importantly their companionship, made the cold mornings in the stream, long sampling days, and crowded lab benches in 226, quite memorable. It was a pleasure working with each one of them and I wish them all a wonderful future. Finally, my family has given me the strength to always keep going. Thank you to my husband, John, because while he doesn’t always ‘get it’, he loves and supports me everyday, gently pushing me to get it done! My mom, sister, two brothers and their families have been by my side every step of the way – showing interest in my passion, trusting in my travels, helping with Charlie and around the house so I could get work done, and loving me no matter what. I am truly grateful. ! ix! TABLE OF CONTENTS ABSTRACT………………………………………………………………………....iv DEDICATION……………………………………………………………………... vii ACKNOWLEDGMENTS…………………………………………………………. viii LIST OF FIGURES………………………………………………………………. xiii LIST OF TABLES………………………………………………………………... xv CHAPTERS I. INTRODUCTION & LITERATURE REVIEW……………………….1 Introduction………………………………………………………… 1 Literature Review………………………………………………….. 3 References………………………………………………………….. 15 II. DISPERSAL AND UPSTREAM MIGRATION OF AN AMPHIDROMOUS NERITID SNAIL: IMPLICATIONS FOR RESTORING MIGRATORY PATHWAYS IN TROPICAL STREAMS……………………………..20 Summary…………………………………………………………… 20 Introduction…………………………………………………………22 Methods……………………………………………………………. 25 Results……………………………………………………………… 31 Discussion ………………………………………………………….33 Acknowledgments ………………………………………………….39 Tables………………………………………………………………. 41 ! "! Figures………………………………………………………………50 Appendices………………………………………………………….54 References………………………………………………………….. 63 III. VARIABILITY IN HABITAT TEMPLATE AND BENTHIC COMMUNITY RESPONSE TO ANTHROPOGENIC WATER REMOVAL IN TROPICAL MOUNTAIN STREAMS.……………………………………………...69 Abstract……………………………………………………………..69 Introduction ………………………………………………………...70 Methods …………………………………………………………….74 Results ……………………………………………………………...79 Discussion ………………………………………………………….85 Acknowledgments ………………………………………………….91 Tables………………………………………………………………. 92 Figures……………………………………………………………... 97 References………………………………………………………….