COMMUNITY STRUCTURE AND ENERGY FLOW WITHIN RHODOLITH HABITATS AT SANTA CATALINA ISLAND, CA A Thesis Presented to The Faculty of the Department of Marine Science San José State University In Partial Fulfillment Of the Requirements for the Degree Master of Science In Marine Science by Scott Stanley Gabara December 2014 © 2014 Scott S. Gabara ALL RIGHTS RESERVED The Designated Thesis Committee Approves the Thesis Titled COMMUNITY STRUCTURE AND ENERGY FLOW WITHIN RHODOLITH HABITATS AT SANTA CATALINA ISLAND, CA By Scott Stanley Gabara APPROVED FOR THE DEPARTMENT OF MARINE SCIENCE SAN JOSÉ STATE UNIVERSITY December 2014 Dr. Diana L. Steller Moss Landing Marine Laboratories Dr. Michael H. Graham Moss Landing Marine Laboratories Dr. Scott L. Hamilton Moss Landing Marine Laboratories ABSTRACT COMMUNITY STRUCTURE AND ENERGY FLOW WITHIN RHODOLITH HABITATS AT SANTA CATALINA ISLAND, CA by Scott Stanley Gabara The purpose of this study was to describe the floral and faunal community associated with rhodolith beds, which are aggregations of free-living coralline algal nodules, off of Santa Catalina Island. Surveys of macroalgal cover, infaunal and epifaunal invertebrates, and fishes suggest rhodolith beds off Santa Catalina Island support greater floral and faunal abundances than adjacent sand habitat. Community separation between rhodolith and sand habitats was due to increased presence of fleshy macroalgae, herbivorous gastropods, and greater abundance of infaunal invertebrates dominated by amphipods, mainly tanaids and gammarids. Stable isotopes were used to determine important sources of primary production supporting rhodolith beds and to identify the major pathways of energy. Stable isotopes suggest the rhodolith bed food web is detrital based with contributions from water column particulate organic matter, drift kelp tissue, and kelp particulates from adjacent kelp beds. ACKNOWLEDGEMENTS I am indebted to many people who have helped me over this journey. First I would like to thank Diana Steller, a great teacher, advisor, and friend, thank you for giving me your guidance, your love of the underwater environment and diving, and your ability to enjoy life and always look at the bright side. I would like to thank my committee member, Scott Hamilton, for inspiring me and providing a great role model. I would like to thank my committee member, Michael Graham, for helping me grow a thick skin, encouraging me to be an objective scientist, and for the time he put into helping me understand and appreciate science and its ability to expand our sphere of knowledge. I would like to thank many people that have had large impacts on me and helped me get this beast of a thesis done including: Paul “PT” Tompkins, Bruce Finney, Rita Mehta, Jack Redwine, Michelle Marraffini, Mike Fox, Arley Muth, Will Fennie, Sarah Jeffries, Kristin Meagher Robinson, Everett Robinson, Ben Higgins, Dan van Hees, Kelley van Hees, Ian Moffit, Kai Kopecky, Sarah Sampson, Cheryl Barnes, Stephen Loiacono, Christian Denney, Angela Szesciorka, Clint “DS” Collins, Erin Loury, Sara Tanner, Craig Hunter, Alex Macleod, Alex Olson, Rob Franks, Jocelyn Douglas, Jim Harvey, John Douglas, James Cochran, William “Billy” Cochran, Michelle Keefe, Ivano Aiello, Rhett Frantz, Jason Adelaars, Gary Adams, Joan Parker, Brynn and Zach Kaufman, Matt Edwards, Jane Schuytema, the Benthic Ecology and Experimental Research, Phycology in General (BEERPIGs) group, realistically the entire MLML lab population for both physical and emotional support, the USC Wrigley Institute with special thanks to Trevor Oudin, Lauren Czarnecki Oudin, and Kellie Spafford, Becky “Smalls” Locker for her endless support, and my family for their encouragement. vii This would not be possible without the aid from my funding sources: The American Academy of Underwater Sciences (AAUS) Kevin Gurr Scholarship Award, Moss Landing Marine Laboratories (MLML) Signe Lundstrom Memorial Scholarship, Moss Landing Marine Laboratories (MLML) 2013 Wave Award, Council on Ocean Affairs, Science & Technology (COAST) Student Award for Marine Science Research, David and Lucile Packard Foundation Award, and the Dr. Earl H. Myers and Ethel M. Myers Oceanographic and Marine Biology Trust. vii TABLE OF CONTENTS List of Figures…………………………………………………………………………….ix List of Tables……………………………………………………………………………...x Introduction………………………………………………………………………………..1 Chapter I: Abstract……………………………………………………………………….…...3 Introduction………………………………………………………………..………4 Methods…………………………………………………………………..………..8 Results………………………………………………………………………..…..12 Discussion…………………………………………………………………….….21 Literature Cited………………………………………………………………..…28 Chapter II: Abstract……………………………………………………………………….….35 Introduction………………………………………………………………..……..36 Methods…………………………………………………………………..………39 Results………………………………………………………………………..…..46 Discussion…………………………………………………………………….….55 Literature Cited………………………………………………………………..…61 Conclusions………………………………………………………………………………69 Literature Cited…………………………………………………………………………..70 Appendices……………………………………………………………………………….76 Appendix A: Biodiversity of California rhodolith beds……………...….76 13 15 Appendix B: Stable isotope ratios, δ C and δ N, for primary producers and consumers from Isthmus Cove by season…………….78 viii LIST OF FIGURES Chapter I: Figure 1. Map of survey locations off Santa Catalina Island……………………………...9 Figure 2. Percent cover of primary substrate within (A) rhodolith and (B) sand habitats at Catalina Island, for all sites combined……………...…….......12 Figure 3. Species accumulation curves for rhodolith (red lines) and sand habitat (black lines) by the (A) Macroalgae, (B) Infauna, (C) Epifauna, and (D) Fish functional groups………………….………………..……………14 Figure 4. Non-metric multidimensional scaling (nMDS) plot based on a square root transformed Euclidean distance matrix of the combined community...…………………………………………………………...……...16 Figure 5. Non-metric multidimensional scaling (nMDS) plots based on square root transformed Euclidean distance matrices of (A) Macroalgae, (B) Infauna, (C) Epifauna, and (D) Fishes. ……..…………………………...18 Figure 6. Abundance of (A) Macroalgae, (B) Infaunal invertebrates, (C) Epibenthic invertebrates, and (D) Fishes, within rhodolith and sand habitats.…………...20 Chapter II: Figure 1. Map of Santa Catalina Island with inset of Isthmus cove and the rhodolith bed where collections of primary producers and consumers were made……………………………...……………………………………..40 Figure 2. δ13C versus δ15N biplot of rhodolith bed invertebrate consumers values (mean±SD) pooled across sampling times from Isthmus Cove………..49 Figure 3. Diet contribution of pooled SPOM, SOM, and drift kelp to planktivore, detritivore, herbivore, and predator trophic groups from a SIAR mixing model…………………………………………………………………………..51 Figure 4. δ13C versus δ15N biplot of rhodolith bed primary producers and potential herbivore consumers by season……………………………………..53 Figure 5. Percent diet contribution to the gastropods (A) Lirularia spp. and (B) Megastraea undosa………………………………………………………...54 Figure 6. Generalized rhodolith bed food web model based on δ13C and δ15N biplot, incorporating pooled primary producers and consumers from Isthmus Cove………………………………………………………………….55 ix LIST OF TABLES Chapter I: Table 1. Mean ± SE values for sediment size classes from cores in rhodolith and sand habitats during spring and winter…………………………….………13 Table 2. Tests for differences in assemblage by habitat and season based on two-way permutational multivariate analysis of variance (PERMANOVA)……………………………………………………………….16 Table 3. Relative contribution of taxa to the observed differences in the overall community assemblage by (A) habitat and (B) season. Similarity percentage (SIMPER) analysis listed for taxa contributing over 50% to dissimilarity. …………………………………………………...…...………16 Table 4. Tests for differences in assemblage by habitat and season based on two-way permutational multivariate analysis of variance (PERMANOVA) for (A) macroalgae, (B) infauna, (C) epifauna, and (D) fishes.………………………………………………………...……..…18 Table 5. Relative contribution of (A) macroalgal, (B) infaunal, and (C) epifaunal taxa, to the observed differences in assemblage by habitat. Relative contribution of (D) epifaunal taxa to the observed differences in assemblage by season. Similarity percentages (SIMPER) analysis listed for taxa contributing to over 90% dissimilarity. Abundance values are averages between habitats or seasons..……….…………...……..…19 x INTRODUCTION High biodiversity has been correlated with structural complexity in both terrestrial (Simpson 1964) and marine systems (Ormond et al. 1997, Kamenos et al. 2004). Foundation species are critical to the establishment and persistence of populations and increase the structural complexity of the benthos (Bruno & Bertness 2001). The structure and dynamics of foundation species have broad consequences for associated biota, community dynamics, ecosystem function, and stability (Ellison et al. 2005). In marine systems, conspicuous foundation species include kelps (Estes & Palmisano 1974, Graham 2004), salt marsh grasses (Bertness & Hacker 1994, Bertness et al. 1999), mangroves (Nagelkerken et al. 2008, Nagelkerken & Faunce 2008, Nagelkerken et al. 2010), sea grasses (Ellison & Farnsworth 2001, Ellison et al. 2005, Nagelkerken & Faunce 2008), and corals (Luckhurst & Luckhurst 1978, Alvarez-Filip et al. 2009). Marine foundation species provide a variety of benefits to community inhabitants such as generating habitat, reducing environmental and predation stresses, enhancing retention of propagules