UNIVERSITY OF CALIFORNIA SANTA CRUZ Life in a patchy world: species-habitat relationships link macroalgal communities to higher trophic levels in temperate rocky reefs A dissertation submitted in partial satisfaction of the requirements for the degree of DOCTOR OF PHILOSOPHY in ECOLOGY AND EVOLUTIONARY BIOLOGY by Brenna Mahoney September 2014 The Dissertation of Brenna Mahoney is approved: _____________________________ Professor Pete Raimondi, Chair _____________________________ Professor Mark Carr _____________________________ Professor Michael Graham _____________________________ Tyrus Miller Vice Provost and Dean of Graduate Studies Copyright © by Brenna Mahoney 2014 Table of Contents List of Tables ........................................................................................................................ v List of Figures ..................................................................................................................... vi Abstract .............................................................................................................................. viii Acknowledgements ........................................................................................................... xii Introduction ......................................................................................................................... 1 1. Chapter 1 - Algal assemblage structure drives spatial variability in associated invertebrates along a wave exposure and swell disturbance gradient ...................... 4 1.1 Abstract ..................................................................................................................................... 4 1.2. Introduction ........................................................................................................................... 5 1.3 Methods .................................................................................................................................. 11 1.3.1 Study system and organisms ....................................................................................................... 11 1.3.2 Site characterization ...................................................................................................................... 12 1.3.3 Spatial and temporal patterns of algal assemblage ................................................................ 13 1.3.4 Spatial and temporal patterns of associated invertebrate assemblage ............................. 13 1.3.5 Linking algal and invertebrate assemblages ............................................................................ 14 1.4 Results .................................................................................................................................... 17 1.4.1 Site characterization ...................................................................................................................... 17 1.4.2 Spatial and temporal patterns of algal assemblage .................................................... 17 1.4.3 Spatial and temporal patterns of associated invertebrate assemblage ............................. 18 1.4.4. Linking algal and invertebrate assemblages ........................................................................... 18 1.5 Discussion ............................................................................................................................. 19 1.6 Tables ..................................................................................................................................... 25 1.7 Figures .................................................................................................................................... 30 2. Chapter 2 – Contribution of fish predation to differences in prey assemblage as a function of host algal species ....................................................................................... 32 2.1. Abstract ................................................................................................................................. 32 2.2. Introduction ......................................................................................................................... 33 2.3. Methods ................................................................................................................................ 36 2.3.1. Study site ............................................................................................................................ 36 2.3.2. Fish diet composition ..................................................................................................... 36 2.3.3. Diet items associated with different algal species ................................................................ 37 2.3.4. Prey response in absence of predation ................................................................................... 38 2.4. Results ................................................................................................................................... 41 2.4.1. Fish diet composition .................................................................................................................. 41 2.4.2. Diet items associated with different algal species ................................................................ 41 2.4.3. Prey response in absence of predation ................................................................................... 42 2.5. Discussion ............................................................................................................................ 42 iii 2.6. Tables .................................................................................................................................... 47 2.7. Figures .................................................................................................................................. 48 3. Chapter 3 – Prey availability and feeding mechanics determine ontogeny of habitat selection of a microcarnivorous fish (Oxylebius pictus) .............................. 52 3.1. Abstract ................................................................................................................................. 52 3.2. Introduction ......................................................................................................................... 53 3.3. Methods ................................................................................................................................ 56 3.3.1. Study Site ........................................................................................................................................ 56 3.3.2. Size of prey available in the environment .............................................................................. 57 3.3.3. Ontogenetic differences in diet and prey selectivity of Oxylebius pictus .......................... 57 3.3.4. Ontogenetic changes in jaw morphology of Oxylebius pictus ................................ 59 3.3.5. Algal associations of Oxylebius pictus ......................................................................................... 60 3.4. Results ................................................................................................................................... 61 3.4.1. Size of prey available in environment ..................................................................................... 61 3.4.2. Ontogenetic differences in diet and prey selectivity of Oxylebius pictus .......................... 62 3.4.3. Ontogenetic changes in jaw morphology of Oxylebius pictus ............................................. 64 3.4.5. Algal associations of Oxylebius pictus ......................................................................................... 64 3.5. Discussion ............................................................................................................................ 65 3.6. Figures .................................................................................................................................. 71 Discussion .......................................................................................................................... 78 Bibliography ....................................................................................................................... 82 iv List of Tables Table 1-1. Dissimilarity of percentage results determined by SIMPER analysis showing algal species that contribute most to average dissimilarity (cut-off percentage: 90%) between algal assemblages at each site surveyed. Average dissimilarity values between sites are in bold. ...................................................................................... 25 Table 1-2. Mean abundance of invertebrate groups collected from six algal species and standardized to algal dry weight (#invertebrate/g algal replicate). Total and percent abundance of invertebrate groups reported. .......................................................... 26 Table 1-3. Results of PERMANOVA testing differences of invertebrate assemblage composition as a function of site and sample month. Significant differences (p<0.05) between sites are indicated in bold. ......................................................... 27 Table 1-4. Results of PERMANOVA testing differences in invertebrate assemblage composition as a function of algal species and site. ............................................... 28 Table 1-5. Correlation coefficient results from the BIOENV procedure for the top ten models of algal species explaining the invertebrate