The native oyster recruitment study in Central and South San Francisco Bay 2006-07

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NATIVE OYSTER RECRUITMENT STUDY IN CENTRAL AND SOUTH SAN FRANCISCO BAY 2006-07 By Sumudu Welaratna The Olympia oyster, Ostrea conchaphila, once abundant in West Coast estuaries of North America, is now uncommon in the San Francisco Bay, especially the South Bay. This study evaluated native oyster recruitment, at three sites each, in the South and Central Bay, using three experimental substrates: oyster shell strings, PVC recruitment tiles, and oyster shell bags. Oyster numbers and data on other settling organisms were recorded bi-monthly from October 2006 to October 2007. Oyster settlement was seasonal, major spatfall occurring between June 2007 and October 2007. Compared to the Central Bay, the South Bay was more productive for oyster settlement and had higher abundance of other hard shelled organisms. Of the three substrates, shell bags, which offered more surface area, were most productive. This research suggests Ostrea conchaphila restoration efforts in the South Bay may be successful, but more information is needed on conditions promoting long-term oyster survival and reproduction. ACKNOWLEDGEMENTS I would like to thank Dr. Lynne Trulio, the Chair of my thesis committee and the one who introduced me to the species, for the advice and friendship throughout this project. I also thank Marilyn Latta, the project manager at Save The Bay who welcomed me to work with her, and generously shared her knowledge and funding to support my thesis work. I very much thank my family for so much moral, intellectual and logistical support throughout these years in school, and especially my father for providing all this and financial support too! I also thank Rena Obernolte and Dr. Will Russell for all their help and advice as members of my thesis committee, Dr. Rachel O'Malley and Dr. Katherine Cushing and fellow students for great critiques, and especially Jude Stalker and Melanie Lopes of Save The Bay for hours of good work and good times in the field. Many people contributed to specific aspects of this project: Design: Marilyn Latta, Dr. Lynne Trulio, Dr. Chela Zabin, Rena Obernolte, Natalie Manning-Cosentino, Jude Stalker; Site Access: Marilyn Latta, Paula Bettencourt, City of Mountain View; Darren Anderson, City of Palo Alto; Ray Fox, Caltrans; Andy Cohen, San Francisco Estuary Institute; Dr. Lynne Trulio, South Bay Salt Pond Restoration Project; Robert Johnson, Oyster Point Marina; Peter Conner; and Craig Ponsford; Field Work: Marilyn Latta, Jude Stalker, Melanie Lopes, Dr. Chela Zabin, Rena Obernolte, Sarikka Attoe, Sri Welaratna, Marilyn Galloway, Dr. Lynne Trulio, Lara Martin, Peter Connor, Craig Ponsford, Save the Bay Field Staff, and many more community volunteers; Funding: Save The Bay, National Oceanic and Atmospheric Administration, Restore America's Estuaries, and San Jose State University College of Social Sciences. TABLE OF CONTENTS Introduction 1 Background 3 Research on Existing Oyster Populations and Recruitment 13 Restoration Efforts in San Francisco Bay 19 Native Oyster Recruitment Study in Central and South San Francisco Bay 2006-07 28 Methods 29 Results 45 Discussion 56 References 67 Appendix: Reproductions of Required Permits 71