I SPATIAL HABITAT VARIATION in a GREAT PLAINS RIVER
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SPATIAL HABITAT VARIATION IN A GREAT PLAINS RIVER: EFFECTS ON THE FISH ASSEMBLAGE AND FOOD WEB STRUCTURE by JEFFREY LAINE EITZMANN B.S., Kansas State University, 2005 A THESIS submitted in partial fulfillment of the requirements for the degree MASTER OF SCIENCE Division of Biology College of Arts and Sciences KANSAS STATE UNIVERSITY Manhattan, Kansas 2008 Approved by: Major Professor Dr. Craig Paukert i ABSTRACT We investigated spatial variation in fish assemblage and food web structure in the Kansas River, USA in relation to habitat changes. Fishes were collected at ten sites throughout the Kansas River for assessing assemblage structure in summer 2007 using fish community metrics and at 3 sites in 2006 for food web structure using stable isotope analysis. Satellite imagery indicated riparian habitat on the Kansas River was dominated by agriculture in the upper reaches (>35%) and tended to increase in urban land use in the lower reaches (>58%). Instream habitat complexity also decreased with increased urban area (<25%) becoming more channelized. Jaccard’s similarity and percent similarity indices suggested that large-bodied fishes show changes in species presence and composition longitudinally within the river. Also, reaches directly above Bowersock Dam in Lawrence, Kansas and below the Johnson County Weir, near Kansas City, Kansas had low percent similarity compared to other reaches, suggesting the dam and the weir affect community composition. Canonical correspondence analysis indicated that species that prefer high velocity flows and sandy substrate (blue sucker and shovelnose sturgeon) are associated with the upper river reaches. Also, there was a higher abundance of omnivorous and planktivorous fish species in the lower more channelized river. The lower reaches contain more tolerant, macrohabitat generalist species and the upper river contained more intolerant, fluvial specialist species. Fish, macroinvertebrates, and detritus were collected at three river reaches classified as the heterogeneous instream habitat (>40% grass islands and sand bars) intermediate (22% grass islands and sand bars), and homogeneous (6% grass islands and sand bars) instream habitat reaches in June 2006. Riparian land use (proportion as agricultural and urban) was related to instream habitat with homogeneous areas having more urban riparian area compared to the heterogeneous and intermediate reaches. The heterogeneous habitat reach had ii higher variability in δ13C for fish classified as piscivores/invertivores (P=0.029) and macroinvertebrates (P=0.004) suggesting the complex habitat in the heterogeneous habitat reach provided more variable food sources. The δ15N values also indicated that ten of the twelve fish species tended to consume prey at higher trophic levels in the heterogeneous habitat reach suggesting a more complex food web. Land use practices are leading to homogenization of instream habitat and this homogenization of habitats may be related to food web diversity and trophic position of fishes. Conserving intolerant, native species in the Kansas River may require maintaining suitable habitat for these species and restoration of impacted areas of the river. iii Table of Contents List of Figures………………………………………………….……………..................………..vi List of Tables……………………………………………………………………………………viii Acknowledgements……………………………………………………………………………….ix Preface……………………………………………………………………………..........................x CHAPTER 1 – Longitudinal differences in habitat complexity and fish assemblage structure of a Great Plains river …..………………………... 1 Abstract……………………………………………………………………………………….. 1 Introduction…………………………………………………………………………………… 2 Materials and methods………………………………………………………………………... 4 Study Area………………………………………………………………………………... 4 Riparian and instream habitat…………………………………………………………….. 5 Field collections…………………………………………………………………………... 6 Data analysis……………………………………………………………………………… 7 Results………………………………………………………………………………………… 9 Riparian and instream habitat…..………………………………………………………… 9 Field collections…………………………………………………………………………. 10 Discussion…………………………………………………………………………………… 14 Literature Cited……………………………………………………………………………… 19 Figures and Tables…………………………………………………………………………... 24 CHAPTER 2 – Spatial variation in habitat: effects on food web structure of a Great Plains River..………………………..………………………... 34 Abstract……………………………………………………………………………………… 34 Introduction………………………………………………………………………………….. 34 Materials and methods………………………………………………………………………. 38 iv Study area………………………………………………………………………………...38 Riparian and instream habitat…………………………………………………………… 39 Field collections…………………………………………………………………………. 39 Stable isotope analysis…………………………………………………………………... 40 Stomach content analysis………………………………………………………………...42 Data analysis…………………………………………………………………………….. 42 Results……………………………………………………………………………………….. 43 Riparian and instream habitat………………………………………………………….... 43 Fish and macroinvertebrate collection…………………………………………………... 44 Primary consumers……………………………………………………………………….45 Detritivorous and omnivorous fishes……….…………………………………………... 45 Piscivorous and invertivorous fishes……………………………………………………. 47 Stomach content and feeding guild analysis…………………………………………….. 47 Discussion…………………………………………………………………………………… 48 Literature cited………………………………………………………………………………. 53 Figures and Tables…………………………………………………………………………... 59 Appendix A – Diet items of Kansas River fishes ……...………………………………..……… 67 v LIST OF FIGURES Figure Page 1.1: Map of the Kansas River where it forms at the confluence of the 28 Republican and Smoky Hill Rivers and drains 274 km east to the Missouri River. The black boxes represent the 10 reaches sampled on the Kansas River in summer 2007. 1.2: Mean proportion (± SE) of A) riparian and B) instream habitat, and C) mean 29 width of the river and number of channels at each reach sampled in the Kansas River from satellite imagery data from September 2006. The solid lines represent Bowersock Dam (BS) and the Johnson County Weir (JC). 1.3: Mean species richness and Shannon Weiner diversity (± SE) for 30 electrofishing samples and seining samples by each reach sampled in the Kansas River in summer 2007. Identical lower case letters represent reaches that were not significantly different among reaches for species richness or diversity. No letters indicate no significant differences among reaches. The solid lines represent Bowersock Dam (BS) and the Johnson County Weir (JC). 1.4: Canonical correspondence analysis of log-transformed relative abundance 31 of species for the electrofishing samples and seine samples collected in the Kansas River in summer 2007 and how they are explained by riparian and instream environmental variables. Species names are shown in Table 1.2. The environmental variables include; proportion of agricultural land use (Agri), mean bottom water column flow (Bot flow, m s-1), the proportion of the bankfull width that is main channel (Channelized), the mean number of channels (# Channels), conductivity (Cond, μS), mean depth (Depth, m), the proportion of instream habitat as grass islands (Grass Is), mean middle water column flow (Mid flow, m s-1), the proportion of the shoreline habitat as rip-rap habitat (RR), river kilometer from Missouri River confluence(River km), the proportion of the shoreline habitat as sand bar habitat (SA), Secchi depth (Secchi, m), the proportion of urban land use (Urban) and mean bankfull width (Width). 1.5: Canonical correspondence analysis of log-transformed relative abundance 32 of feeding guilds for fishes collected from the electrofishing samples and seine samples collected in the Kansas River in summer 2007 and how they were explained by riparian and instream environmental variables and reach. The feeding guilds include; detritivores, herbivores, invertivores, omnivores, and piscivores. The environmental variables include; mean bottom water column flow (Bot flow, m s-1), the proportion of the river as main channel (Channelized), the mean number of channels (# Channels), conductivity (Cond, μS), the proportion of instream habitat as grass islands (Grass Is), the vi proportion of the main-channel border habitat as rip-rap habitat (RR), river kilometer from Missouri River confluence (River km), the proportion of the shoreline habitat as sand bar habitat (SA), the proportion of instream habitat as sand bars (SABR), mean temperature, the proportion of urban land use (Urban), and mean river width (Width, m). 1.6: Mean principal component axis 1 score with the presence and absence of 33 each habitat guild and tolerance level for fishes captured with electrofishing (catch per hour) and seining (catch m-2). Lower case letters represent habitat guilds and tolerance levels that significantly differed in principal component means for presence and absence. 2.1: Mean proportion (± SE) of A) riparian and B) instream habitat from satellite 62 imagery data from September 2006. Identical lower case letters represent areas that were not significantly different among habitat types for each reach. White bars represent reach 1, grey bars represent reach 2, and black bars represent reach 3. The P in the headings on the x-axis represents the instream habitat variables that are proportions. 2.2: Mean (± SE) δ15N and δ13C of samples collected in the heterogeneous habitat 63 reach (rkm 229 to 235), intermediate reach (rkm 120 to 126), and homogeneous habitat reach (rkm 24 to 30) from the Kansas River in summer 2006. Species codes are given in Table 2.1. 2.3: Mean trophic position based on stable isotope analysis for all fish species