Population biology of Undaria pinnatifida in central California

Abstract

POPULATION BIOLOGY OF UNDARIA PINNATIFIDA IN CENTRAL CALIFORNIA by Diana Kohtio This study combined monitoring and experimental techniques to examine natural population parameters and physiological response to temperature of the invasive kelp Undaria pinnatifida in Monterey Harbor, California. Natural population density, reproductive condition, and seawater temperature were recorded throughout a 20-month study. Recruitment was sampled in experimental sporophyte density plots throughout a 9-month experiment. Physiology experiments were conducted in two temperature treatments over a 55-day period coincident with reproduction measurements and nutrient analysis. Natural population fluctuation and reproductive condition appeared to respond to seasonal variations in temperature range. Warm temperature treatments increased C:N and blade senescence but decreased time to reproduction and peak spore output. Sporophyte density reduced recruitment at high levels, likely resulting from intra-specific competition. Because Undaria pinnatifida is an opportunistic species responding to changes in an unpredictable environment it may have a distinct advantage when it comes to invasion success. ACKNOWLEDGEMENTS I would like to thank my parents for giving me the opportunity to attend graduate school and conduct this research. Thanks to the Beerpigs for all of their kind support and insightful feedback throughout my tenure at Moss Landing Marine Laboratories. Special thanks to my advisor Mike Graham and committee members Steve Lonhart and Kenneth Coale for their guidance. Thanks also to Brent Hughes, Laurie McConnico, and Mike Foster who helped shape this study from start to finish. This project was supported by the Packard Foundation, the Earl and Ethly Meyers Foundation, and the San Jose State University Lottery Fund.