Lf65J XV,11 0 COMMUNITY ECOLOGY OF THE INVASIVE INTERTIDAL BARNACLE CHTHAMALUS PROTEUS IN HAWAI'I 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 ZOOLOGY (ECOLOGY, EVOLUTION AND CONSERVATION BIOLOGY) AUGUST 2005 By Chela Juliet Zabin Dissertation Committee: Andrew D. Taylor, Chairperson Robert A. Kinzie III Sheila Conant Curtis C. Daehler Craig Smith ACKNOWLEDGMENTS I thank my advisor, Andrew Taylor, for his kind support over the past seven years and in particular, for help with experimental design and analysis. Committee members Curtis Daehler, Craig Smith, Robert Kinzie and Sheila Conant provided excellent discussions and comments that greatly improved the dissertation. James T. Carlton, Peter T. Raimondi and John Zardus assisted with both practical and conceptual matters. Funding was provided by a National Science Foundation Graduate Teaching Fellowship in K-12 Education, an NSF Graduate Research Fellowship, the Edmondson Research Fund, and the Ecology, Evolution and Conservation Biology program. Funds for undergraduate assistants and supplies were provided by a grant from u.s. Sea Grant to Michael Hadfield. The Smithsonian Tropical Research Station hosted me at the Galeta Marine Laboratory in Panama and the CARMABI Foundation hosted me in Curaqao. L. Scott Godwin, Steve L. Coles, and Lucius Eldredge from the Bernice P. Bishop Museum generously shared data and allowed me to use lab space and taxonomic reference materials. Field assistance was provided by: Inez Campbell in Panama, Elroy Cocheret de la Moriniere in Curaqao, and Andrew Altieri, Kim del Carmen, Anuschka Faucci, Vanessa Fread, Julie Goldzman, Aaron Hebshi, Brian Nedved, Stacy Pang, Alan Parsa and Pakki A. Reath in Hawaii. Anuschka Faucci, L. Scott Godwin, Regina Kawamoto, Bill Newman, Pakki A. Reath, Jennifer E. Smith and Alan Southward assisted with species identifications. Finally, I thank my companion of 13 years, Blu Forman, for assisting in the field, 111 building equipment, driving cars in foreign countries, providing computer advice, creating maps for the dissertation, and maintaining a sense ofhumor throughout the graduate school experience. IV ABSTRACT Chthamalus proteus is the most recent invasive barnacle in the Hawaiian Islands, arriving some time after 1973. A native ofthe GulfofMexico, Caribbean Sea and southwestern Atlantic Ocean, C. proteus is now found throughout the main Hawaiian Islands. While still mainly restricted to harbors on neighbor islands, C. proteus has spread around the island ofOahu, inhabiting the intertidal zone in open-coast settings and attaining high abundance in wave-protected harbors and bays. Aspects ofthe barnacle's life history were investigated at several locations within its home range and in Hawaii. While there were some differences in fecundity and vertical range between locations, there was overall little change in life history characteristics between the native and invaded ranges. We predict that the barnacle will continue to spread throughout the islands and to other areas in the Pacific that receive shipping traffic from Hawaii. Competitive interactions between C. proteus and two other barnacles, an earlier invader, Balanus reticulatus, and the native Nesochthamalus intertextus were investigated at three locations on Oahu. Competition for space does not appear to be occurring between C. proteus and the native barnacle, but the newer invader is able to outcompete B. reticulatus via substrate pre-emption. Variation in recruitment between sites appears to be more important than competition in determining barnacle abundance and which barnacle will be the numerical dominant. Interactions between C. proteus and the native limpet Siphonaria normalis were also v examined. While the presence ofthe limpet enhances settlement ofthe barnacle, limpets prefer barnacle-free areas and move into patches cleared ofbarnacles. Whether interactions between the barnacle and limpet will be positive or negative may vary with densities ofthe two organisms. A "field microcosm" experiment, in which tiles were assembled with one or three species ofnative bivalves and then placed into the intertidal zone, was used to test the idea that higher diversity leads to invasion resistance. There was no difference due to diversity in the communities oforganisms that invaded tiles, but the presence or absence ofcertain bivalves in the original assembled communities led to differences in invaders. VI TABLE OF CONTENTS Acknowledgments ................................... .. 111 Abstract. ........................................ .. v List ofTables " x List ofFigures .................................... .. xiii Chapter I: Introduction................................. I Chapter 2: A Tale ofThree Seas: consistency ofnatural history traits in a Caribbean- Atlantic barnacle introduced to Hawaii Introduction ..................................... .. 5 Study organism ............................ 6 Study objectives ................................. .. 8 Materials and Methods. .............................. .. 9 Life history of C. proteus in Hawaii ...................... .. 9 Larval development ............................ .. 9 Reproduction and seasonality ............. 10 Growth. ................................. .. 10 Mortality ................................. .. 13 Comparison of C. proteus in Hawaii and native range ........... .. 14 Geographic distribution and habitat use ................. .. 14 Reproduction, body size and spatial variation .............. .. 17 Population density ............................. .. 18 Results. ...................................... .. 18 Life history of C. proteus in Hawaii ..................... .. 18 Larval development ............................ .. 18 Reproduction and seasonality ......................." 19 Growth. .................... 21 Mortality ................... 21 Comparison between Hawaii and native range . 24 Geographic distribution and habitat use ... 24 Reproduction, body size and spatial variation .............. .. 31 Population density ............................ ., 34 Discussion ....................................." 34 Status ofinvasion ..............................." 34 Comparison between the Caribbean, Brazil and Hawaii. ......... .. 35 Predicting invasions , 38 Patterns ofchange in invading species ................... ., 41 Appendix A. Localities and habitat data for sites surveyed among the Hawaiian Islands for the presence ofthe alien barnacle Chthamalus proteus . 45 Chapter 3: Battle ofthe barnacle malahini: shifts in dominance between three invading barnacle species, in Kaneohe Bay, Oahu, Hawaii Introduction .................................... 49 Study objectives ............................... .. 53 vii Methods and Materials .............................. .. 54 Study species and site , 54 Initial competition experiment ........................ .. 57 Community-effects study. .......................... .. 58 Invasion experiment ................................ 59 Recruitment and survival ofBalanus reticulatus .............." 59 Results. .............. 60 Initial competition experiment ........................ .. 60 Community-effects study ........................... .. 64 Invasion experiment ............................. .. 66 Recruitment and survival ofBalanus reticulatus ........... 69 Discussion .................................. 71 Chapter 4: Recruitment levels linked to competition outcomes between pairs ofbarnacle species Introduction ...... 78 Materials and Methods ....... 80 Study organisms .................. 80 Competition between C. proteus and N intertextus ........ 81 Neighbor-removal experiments. ................. 81 Recruitment inhibition experiments ................ 85 Growth, mortality and recruitment ofnumerically dominant barnacle . .. 85 Growth calculations .............. 88 Statistical analyses ......................... 89 Comparison to Kaneohe Bay ........................ 90 Recruitment study .............................. 91 Results. ..................................... .. 93 Competition between C. proteus and N intertextus ............ 93 Neighbor-removal experiments. .................... .. 93 Recruitment inhibition experiments ................... .. 97 Growth, mortality and recruitment ofnumerically dominant barnacle .. 98 Comparison to Kaneohe Bay ...................... .. 99 Recruitment study .......................... 100 Discussion .................................. 106 Importance ofcompetition varies between sites 106 Possible factors influencing competition ................ 107 Importance ofrecruitment in Hawaii .................. 110 Larval retention and invasive species .................. 112 Chapter 5: Taking advantage ofaloha: a native limpet may facilitate and then suffer from recruitment of an invasive barnacle in Hawaii's intertidal zone Introduction ...... 114 Materials and Methods .............................. 117 Study organisms ........................... 117 Study site ................................... .. 118 viii Seawall survey .................................. 121 Recruitment preferences ............................. 121 Effects ofS. normalis on recruitment of C. proteus ........... 122 Cages . 122 Barriers . 124 Effects of C. proteus on S. normalis ................. 125 Results . 126 Seawall survey .................................. 126 Recruitment preferences .................... 129 Effects of S. normalis on recruitment of C. proteus