ASPECTS OF COMMUNITY ECOLOGY ON WAVE-EXPOSED ROCKY HAWAI‘IAN COASTS A DISSERTATION SUBMITTED TO THE GRADUATE DIVISION OF THE UNIVERSITY OF HAWAI‘I IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY IN BOTANY (ECOLOGY, EVOLUTION AND CONSERVATION BIOLOGY) DECEMBER 2006 By Christopher Everett Bird Dissertation Committee: Celia M. Smith, Chairperson Kent W. Bridges David C. Duffy Leonard A. Freed E. Alison Kay Halina M. Zaleski We certify that we have read this dissertation and that, in our opinion, it is satisfactory in scope and quality as a dissertation for the degree of Doctor of Philosophy in Botany (Ecology, Evolution and Conservation Biology). DISSERTATION COMMITTEE ________________________________ Chairperson ________________________________ ________________________________ ________________________________ ________________________________ ________________________________ ii Copyright 2006 Christopher Everett Bird All Rights Reserved iii DEDICATION This one goes out to my mom Betsy Bird; my dad George Bird; my grandmother Ethel Bird; my sisters and their families Gwendolyn, Scott, Alex, Mitchell, and Nicholas Bottomley, Evelyn, Mike, Andrew, and Ian Kirner; my best friend John Swistak; my boyz in NL1; my girlz in tha 808; and all the rest of my friends. You are the people who stood by my side, no matter what. Thank you for the good times, the support, and the love. I owe it all to you. iv ACKNOWLEDGMENTS I would like to thank the University of Hawaii Sea Grant College (this is publication XD- 02-02), University of Hawaii Ecology, Evolution and Conservation Biology Program, National Parks Service, and Northwestern Hawaiian Islands National Monument for funding the research presented in this dissertation. This dissertation would not have happened without the inspiration of a few special people. Robin Chazdon was singularly responsible for turning me on to community ecology when I was a sophomore at the University of Connecticut. Despite the fact that her interests lied in rainforest ecology, and getting me to do work for her, Robin unselfishly guided me towards inspiring research articles in marine ecology and helped me get a position as a marine biology technician. Francis Trainor was a fantastic undergraduate mentor who encouraged me to cast a wide net and keep my mind open to new ideas. Kelly Benoit-Bird convinced me to move to Hawaii against my better judgment. However, it turned out to be a great adventure, and I found the natural system that I was born to study - the wave-exposed Hawaiian rocky intertidal community. Celia Smith accepted me into her laboratory as a graduate student when no other professor would. I know that Celia wanted me to be a phycologist, yet she allowed me to follow my heart and explore the ideas and hypotheses that I was most compelled by. Nobody could wish for a nicer and more selfless advisor. v Most community ecologists do not end up conducting a molecular genetic study. Brenden Holland, Rob Toonen, and Brian Bowen are completely responsible for getting me started in phylo- and population genetics. The addition of molecular techniques to my ‘toolbox’ is probably the most important skill I’ve acquired during my graduate work. I have a feeling that I will owe a large portion of the rest of my career to these three. Andy Taylor and Halina Zaleski taught me everything I know about statistics, which I needed every bit of for Chapter 3. The following people helped me conduct the research in this dissertation either for monetary compensation or just the sheer joy of my companionship: Nic Velasco, Megan Dahler, Carly Allen, Masaya Tanaka, Hyunh Ha, Zach Hallinan, Ryan Okano, Kanekoa Shultz, Sonya Stevens, Maya Iriondo-Simek, Dawn Adams, Linda Preskitt, Cheryl Squair, Jennifer Smith, Kimberly Peyton, Andy Hansen, Darin Hayakawa, Mindy Mizobe, Misty-April Kamling-Young, Tomas Sauvage, Sara Peck, Maria Haws, Regina Kawamoto, Brian Nedved, Dan Barshis, Vern Yamanaka, Mark Bertness, Brian Silliman, Bruce Menge, Whit Au, Dave Smith, Steve Kolinski, Kuulei Rodgers, and Eric Brown. If I forgot you in this list of acknowledgments I sincerely apologize. vi ABSTRACT Rocky shores are among the most prevalently studied marine habitat in ecological research, but the tropical Indo-West Pacific rocky shore has received relatively little scientific attention. In this dissertation, I investigate the nature of the physical habitat and biological community along a wave exposure gradient on a Hawai‘ian rocky littoral shore; I experimentally investigate the nature of the interaction between the limpet Cellana sandwicensis, the urchin Colobocentrotus atratus, and the algal community; and I survey the COI locus of the mitochondrion in all three species of endemic Cellana. Along a wave exposure gradient from tide-domination (tidal range > wave height) to wave-domination (wave height > tidal range) the community trends from macrophyte and turf dominated to crustose coralline and grazer dominated, respectively. These biological patterns coincide with a novel physical model of littoral zonation based on the interaction of tidal range and wave height. Unlike tide-dominated shores, where there is merely an intertidal zone, wave-dominated shores are characterized by three physical zones, from high to low shore: the effective intertidal zone, the wave zone, and the submerged intertidal zone. The distinct physical characteristics of each of these habitats can affect processes that drive community structure and ecology, such as predation and physiological stress. The obligate wave-zone species C. atratus and C. sandwicensis exhibit a complex relationship, where both can have either positive or negative effects on the other depending on algal productivity and grazer density. We identified three indirect interactions that involve algal intermediaries: indirect commensalism, habitat facilitation, and exploitative competition. The molecular population structure of each species of vii endemic Cellana exhibited unique patterns. This was surprising given the close phylogenetic relationships and similar life histories of these species. Biogeographic range and position on the shore (littoral vs sublittoral) were the most correlated with the observed population partitioning. We identified moderate to major population subdivision between Kaua‘i and Oahu, Nihoa and Kaua‘i, and Moloka‘i and the other main Hawai‘ian Islands. Overall, we recommend that marine protected areas be delineated on each island in the archipelago and the abundance of Cellana, Colobocentrotus, and erect algae be monitored to assess their effectiveness. viii TABLE OF CONTENTS Dedication.......................................................................................................................... iv Acknowledgements..............................................................................................................v Abstract............................................................................................................................. vii List of Tables .................................................................................................................... xii List of Figures.................................................................................................................. xiii Chapter 1. Literature Review of Intertidal Dynamics and Community Structure ..............1 Abstract..........................................................................................................................1 Introduction......................................................................................................................2 Ecosystem Management on Hawai‘ian Rocky Shores ............................................2 Rocky Intertidal Habitats: Environmental Stress and Disturbance................................6 Physiological Stress and Disturbance ......................................................................6 Physical Stress and Disturbance ..............................................................................9 Littoral Zonation – From Physical to Biological Control......................................13 Biological Factors Affecting Community Structure....................................................20 Dispersal, Recruitment, and Models......................................................................20 Using DNA to Track Larval Dispersal ..................................................................24 Primary Productivity..............................................................................................29 Direct Biological Interactions - Consumption .......................................................30 Direct Biological Interactions – Competition........................................................34 Direct Biological Interactions – Facilitation..........................................................37 Interaction Webs & Indirect Biological Interactions...................................................43 Integrative Models of Community Structure ...............................................................50 Trophic Cascades and Food Chain theory .............................................................51 Menge-Sutherland Environmental Stress Model...................................................52 Recruitment Limitation..........................................................................................55 Incorporation of Positive Interactions into MS......................................................56 Omnivory