MICROHABITAT USE AND MOVEMENTS OF GILT DARTERS (PERCINA EVIDES) IN TWO SOUTHEASTERN STREAMS by JESSICA PAIGE SKYFIELD (Under the Direction of Gary David Grossman) ABSTRACT The patterns of abundance and resource use for most stream fishes are largely unknown. Quantifying resource use of these organisms is a prerequisite for understanding a species’ ecology for theoretical and practical applications. I examined microhabitat use by gilt darters (Percina evides) in two Southeastern streams. I used Principal Component Analysis to examine patterns of use. Darters used microhabitats with higher percent cobble and average velocities than randomly available with male darters deviating from random more than females. In the size- based analyses, larger gilt darters tended to use microhabitats with more heterogeneous substrata and larger amounts of boulder than the smaller size classes. I also conducted a short-term movement study and population estimates. Darters did not seem to conform to the Restricted Movement Paradigm. Nonetheless, 40% of movements were within 5 meters of initial capture. The population density of 0.31 darters/m2 is a point estimate; nonetheless, it provides novel information. INDEX WORDS: microhabitat, Percina, darters, principle component analysis (PCA), benthic, movement, population estimates MICROHABITAT USE AND MOVEMENTS OF GILT DARTERS (PERCINA EVIDES) IN TWO SOUTHEASTERN STREAMS by JESSICA PAIGE SKYFIELD B.A., Rhodes College, 2002 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 2006 © 2006 Jessica Paige Skyfield All Rights Reserved MICROHABITAT USE AND MOVEMENTS OF GILT DARTERS (PERCINA EVIDES) IN TWO SOUTHEASTERN STREAMS by JESSICA PAIGE SKYFIELD Major Professor: Gary D. Grossman Committee: Brett W. Albanese John P. Wares Electronic Version Approved: Maureen Grasso Dean of the Graduate School The University of Georgia May 2006 ACKNOWLEDGEMENTS I would like to acknowledge all that have helped me throughout my academic career, especially during my thesis work at the University of Georgia. This includes, but is not limited to, my major professor, Gary Grossman, committee members Brett Albanese and John Wares, labmates and friends Megan Hill, Bob Rataczjak, Duncan Elkins, and Peter Hazelton, and last but not least my family, Mom, Dad, Gretchen, Walter, Parker, Linton, Isabelle, and my grandparents. iv TABLE OF CONTENTS Page ACKNOWLEDGEMENTS........................................................................................................... iv LIST OF TABLES......................................................................................................................... vi LIST OF FIGURES ...................................................................................................................... vii INTRODUCTION AND LITERATURE REVIEW .......................................................................1 CHAPTER 1 MICROHABITAT USE AND MOVEMENT OF GILT DARTERS (PERCINA EVIDES) IN TWO SOUTHEASTERN STREAMS...............................................12 SUMMARY AND CONCLUSIONS ............................................................................................64 v LIST OF TABLES Page Table 1: Univariate mean and standard deviation (SD) of microhabitat availability and overall darter use data for all sites and seasons.........................................................................36 Table 2: Number and percent of darters by season, sex, and size .................................................37 Table 3: Univariate mean and standard deviation (SD) of microhabitat availability and male and female darter (51-59 mm) use for all sites and seasons ................................................38 Table 4: Univariate mean and standard deviation (SD) of microhabitat availability and size sorted darter use for all sites and seasons......................................................................39 Table 5: Summary of capture and recapture history for positively identifiable darters in Tellico Creek, Autumn 2005 .....................................................................................................40 Table 6: Number and percentage of overall darters moved, by sex, and size class in Tellico Creek, Autumn 2005 .....................................................................................................40 Table 7: Summary statistics (mean, standard deviation) of darter movement in Tellico Creek, Autumn 2005 (downstream movements are absolute value) ........................................40 Table 8: Results of univariate statistical comparisons of darter movement distances...................41 Table 9: AIC calculations using log likelihood for testing models of varying capture-recapture probabilities to estimate population size in Tellico Creek, Autumn 2005. Values and models in bold are ones in the confidence set ...............................................................41 vi LIST OF FIGURES Page Figure 1: Principle Component Analysis (PCA) of constrained random habitat comparisons across sites and seasons: factors 1 and 2. Ellipses represent mean values and 95% confidence intervals. Only loadings ≥ 0.40 are presented.............................................42 Figure 2: Principle Component Analysis (PCA) of constrained random habitat comparisons across sites and seasons: factors 1 and 3 .......................................................................43 Figure 3: Principle Component Analysis (PCA) of constrained random habitat comparisons across sites and seasons: factors 2 and 3 .......................................................................44 Figure 4: PCA of Tellico Summer and Autumn unconstrained microhabitat availability ............45 Figure 5: PCA of Tellico Summer constrained and unconstrained microhabitat availability .......46 Figure 6: PCA of Tellico Autumn constrained and unconstrained microhabitat availability........47 Figure 7: PCA of Coweeta Spring microhabitat use for all darters compared to constrained random microhabitat availability...................................................................................48 Figure 8: PCA of Tellico Summer microhabitat use for all darters compared to constrained random microhabitat availability...................................................................................49 Figure 9: PCA of Tellico Summer microhabitat use for all darters compared to unconstrained random microhabitat availability, factors 1 and 2 ........................................................50 Figure 10: PCA of Tellico Summer microhabitat use for all darters compared to unconstrained random microhabitat availability, factors 1 and 3.........................................................51 vii Figure 11: PCA of Tellico Summer microhabitat use for all darters compared to unconstrained random microhabitat availability, factors 2 and 3.........................................................52 Figure 12: PCA of Tellico Autumn microhabitat use for all darters compared to constrained random microhabitat availability...................................................................................53 Figure 13: PCA of Tellico Autumn microhabitat use for all darters compared to unconstrained random microhabitat availability...................................................................................54 Figure 14: PCA of Coweeta Spring sex linked microhabitat use ..................................................55 Figure 15: PCA of Tellico Summer sex linked microhabitat use ..................................................56 Figure 16: PCA of Tellico Autumn sex linked microhabitat use...................................................57 Figure 17: PCA of Coweeta Spring size linked microhabitat use .................................................58 Figure 18: PCA of Tellico Summer size linked microhabitat use .................................................59 Figure 19: PCA of Tellico Autumn size linked microhabitat use..................................................60 Figure 20: Movement frequency of darters in Tellico Creek Autumn 2005 .................................61 Figure 21: Sex linked movement frequency of darters in Tellico Creek Autumn 2005................62 Figure 22: Size linked movement frequency of darters on Tellico Creek Autumn 2005..............63 viii INTRODUCTION AND LITERATURE REVIEW Temperate lotic systems are spatially and temporally heterogeneous. This heterogeneity creates patches, or microhabitats of varying qualities and types (e.g., Grossman et al. 1995; Wiens 2002) and affects a variety of biological characteristics of lotic species including: 1) distribution (Levins 1963; Grossman et al. 1998), 2) movements (Mundahl and Ingersoll 1983; Railsback et al. 1999; Petty and Grossman 2004), and 3) habitat choice (Freeman and Grossman 1993; Wu and Loucks 1995; Poff and Allan 1995; Grossman et al. 2002, Resitarits, Jr 2005). Quantifying habitat use and movement within this patchy landscape is crucial to understand a species’ ecology (sensu Pulliam 1988; Hanski 1994; Wu and Loucks 1995). Despite this fact, the mechanisms affecting patterns of abundance and resource use for most stream fishes are largely unknown (Grossman et al. 2002). Nonetheless, quantifying resource use patterns of these organisms is a prerequisite for scientifically based management of these species, provides information on habitat variation and quality, and can aid in the construction