Ph.D. Dissertation of Andrew K. Rasmussen
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SPECIES DIVERSITY AND ECOLOGY OF TRICHOPTERA (CADDISFLIES) AND PLECOPTERA (STONEFLIES) IN RAVINE ECOSYSTEMS OF NORTHERN FLORIDA By ANDREW K. RASMUSSEN A DISSERTATION PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY UNIVERSITY OF FLORIDA 2004 ACKNOWLEDGMENTS It is with great pleasure that I acknowledge the many people who are in one way or another connected to this study. First, I would like to recognize Dr. John Capinera and the late Dr. William “Bill” Peters for their vision and dedicated efforts that helped to affiliate the entomology program at Florida A&M University (FAMU) with that of the University of Florida. Dr. Capinera, in his duties as department chair, helped me enormously by providing institutional support. I am also indebted to Debbie Hall for the excellent administrative assistance she has offered throughout my term. I thank Dr. Sunil K. Pancholy for providing me the office and laboratory space used to conduct my research. I express deep gratitude to Dr. Manuel “Manny” Pescador, my graduate committee chairman, boss, and friend, for his confidence and generous commitment of resources to my project. Our many insect-collecting trips were both fun and productive. Appreciation is expressed to the following past members of my committee for their participation: Dr. Gary Buckingham (retired), Dr. Dale Habeck (retired), and Dr. William Peters (deceased). In addition, I thank the other present members of my graduate committee for their committee participation and thoughtful guidance: Dr. Tom Crisman, Dr. Wills Flowers, Dr. Michael Hubbard, and Dr. John Capinera. I am grateful to the following friends and colleagues whose company made fieldwork the most enjoyable and rewarding part of the project: Dick Baumann, Alex Bolques, Stephanie Davis, Dana Denson, Laurence Donelan, Wills Flowers, Steve Harris, Michael Hubbard, Jerome Jones, Boris Kondratieff, Peter Kovarik, Corey Lewis, Charlie O’Brien, Manny Pescador, ii Henry Rasmussen (my son), Don Ray, Bart Richard, Theresa Thom, and Annie Yan. I gratefully acknowledge the following land managers and agencies for granting access to their lands: park managers at Gold Head Branch and Torreya state parks; Greg Seamon (The Nature Conservancy, Apalachicola Bluffs and Ravines Preserve); and Rick McWhite, Carl Petrick, and Dennis Teague, (Natural Resources Branch, Eglin Air Force Base). The single biggest challenge that I faced in this study was the identification of specimens—fortunately I had the help and encouragement of excellent Trichopterists and Plecopterists. I am deeply indebted to Steve Harris for the many ways he contributed, including teaching me the blacklighting method used to collect adults, identifying microcaddisfly specimens from numerous samples, and describing many of the new species discovered during the course of the study. Other Trichopterists who generously provided identifications and verifications were Paul Lago and Jim Glover. I express gratitude to Dick Baumann, Stan Szczytko, and Bill Stark for identifying specimens from some of the difficult stonefly taxa. Lastly, I express heartfelt thanks to my close friends and family for supporting me in countless and immeasurable ways. iii TABLE OF CONTENTS page ACKNOWLEDGMENTS………………………………………………………………...ii ABSTRACT……………………………………………………………………………...vi CHAPTER 1 INTRODUCTION……………………………………………………………………1 Biogeographic Context……………………………………………………………….1 Ravine Ecosystems of Northern Florida……………………………………………...8 Project Objectives and Scope……………………………………………………….14 Description of Study Areas………………………………………………………….15 2 TRICHOPTERA AND PLECOPTERA BIODIVERSITY SURVEY……………...24 Previous Work………………………………………………………………………24 Materials and Methods……………………………………………………………...27 Results and Discussion……………………………………………………………...30 3 ANALYSIS OF TRICHOPTERA COMMUNITY STRUCTURE AND ENVIRONMENTAL RELATIONSHIPS…………………………………………..66 Materials and Methods……………………………………………………………...67 Results and Discussion……………………………………………………………...69 4 TRICHOPTERA AND PLECOPTERA FLIGHT SEASONALITY, AND ADULT EMERGENCE IN A RAVINE SPRINGRUN……………………...82 Materials and Methods.……………………………………………………………..82 Results and Discussion……………………………………………………………..85 5 SUMMARY AND CONCLUSIONS……………………………………………..101 Ravine Biogeography……………………………………………………………...101 Trichoptera and Plecoptera Species Diversity…………………………………….103 Trichoptera Community Structure and Environmental Relationships…………….107 Flight Seasonality and Emergence Study………………………………………….110 Future Research Needs…………………………………………………………….113 iv page REFERENCES CITED…………………………………………………………………115 APPENDIX A TRICHOPTERA DATA MATRIX………………………………………………..123 B PLECOPTERA DATA MATRIX…………………………………………………129 BIOGRAPHICAL SKETCH…………………………………………………………...130 v Abstract of Dissertation Presented to the Graduate School of the University of Florida in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy SPECIES DIVERSITY AND ECOLOGY OF TRICHOPTERA (CADDISFLIES) AND PLECOPTERA (STONEFLIES) IN RAVINE ECOSYSTEMS OF NORTHERN FLORIDA By Andrew K. Rasmussen May 2004 Chair: Manuel L. Pescador Major Department: Entomology and Nematology Species diversity and ecology of insects within the orders Trichoptera (caddisflies) and Plecoptera (stoneflies) were investigated in ravine streams of northern Florida. Ravine ecosystems in Florida are known to support diverse biota, including northern elements and endemic species, but little information concerning stream insects was known. This study is the first to collect stream insects systematically from ravine drainage networks across northern Florida. From West to East, the areas surveyed included streams on Eglin Air Force Base, streams within the Apalachicola and Ochlockonee river basins, and a stream located in peninsular Florida. Caddisfly and stonefly species diversity was investigated at 29 stations along both upper- and lower stream-reaches. Adult and immature insects were collected and identified, and these data were used to characterize caddisfly and stonefly species diversity and adult flight vi seasonality. Adult emergence phenology at a ravine springrun was further investigated using emergence traps. The survey results, based on more than 16,500 specimen identifications, document a diverse fauna of 138 species of Trichoptera and 23 species of Plecoptera. More than 50 species are either ravine-habitat specialists, endemic to small areas of the lower Coastal Plain, or are disjunct from northerly geographic ranges. Sixteen species recorded are listed by the Florida Committee on Rare and Endangered Plants and Animals as Threatened or Rare. At least 12 caddisfly species previously unknown to science were discovered, and 11 of these have subsequently been described and named. Steephead ravine streams in the western panhandle contain a highly endemic fauna, and the ravine fauna of the central panhandle streams has the strongest Appalachian affinities. In order to quantify faunal similarities among stations, cluster analysis was performed on the survey data for macrocaddisfly species collected at 20 stations. Based on the resultant dendogram, 5 macrocaddisfly communities were recognized among the streams sampled. Communities appear to be hierarchically structured according to biogeographic region at a large scale, and by habitat factors related to stream size and ravine type at a smaller scale. Results of detrended correspondence analysis of the same data set supported these conclusions. vii CHAPTER 1 INTRODUCTION With a budding interest in aquatic entomology and lured by the natural beauty and mystery of ravine springruns, I undertook an investigation into the species diversity and ecology of aquatic insects that live in these systems. After more than 10 years of research, I am pleased to present findings concerning 2 important aquatic insect groups: Trichoptera and Plecoptera. The following dissertation on the topic is organized by chapters: Chapter 1 introduces the subject matter, Chapters 2, 3, and 4 address major research objectives, and the final chapter (Chapter 5) provides a summary of the study and conclusions. The specific objectives of this introductory chapter are to i) provide a biogeographic context to the study; ii) present a general characterization of ravine ecosystems in northern Florida; iii) outline the major research objectives; and iv) describe the study areas. Biogeographic Context Taxa Considered Trichoptera and Plecoptera, commonly known as caddisflies and stoneflies, respectively, are diverse and ecologically important orders of aquatic insects. Trichoptera are the largest order of primarily aquatic insects―globally containing over 11,000 nominal species and subspecies (Morse, 2003). In North America, more than 1300 caddisfly species have been reported (Morse, 2003), and approximately 200 of these are known in Florida (Rasmussen, unpublished data). Plecoptera are a smaller order, 1 2 containing about 2000 described species worldwide (Stewart, 2003), approximately 600 species in North America (Stark et al., 1998) and 40 species in Florida (Rasmussen et al., 2003). Almost all caddisfly and stonefly species are confined to aquatic habitats during their immature life stages (Wiggins, 1996; Stewart & Stark, 2002) and occur terrestrially only during the relatively short-lived adult stage. Because of this aquatic dependence, environmental conditions and the resources present in aquatic habitats are critical factors influencing their biodiversity and evolutionary