AN ABSTRACT OF THE DISSERTATION OF Jaime Gómez Gutiérrez for the degree of Doctor of Philosophy in Oceanography presented on December 12, 2003. Title: Comparative Study of the Population Dynamics, Secondary Productivity, and Reproductive Ecology of the Euphausiids Euphausia pacifica and Thysanoessa spinifera in the Oregon Upwelling Region Redacted for Privacy Redacted for Privacy Abstract approved I compare the seasonal abundance variation, population dynamics, fecundity, egg hatching mechanism and success, and apostome ciliate parasites of the euphausiids Euphausia pac?fica and Thysanoessa spinfera from the Oregon coast, USA. Community structure and nearshore distributions were examined from bi-weekly oceanographic surveys (1970-1972). This region has a strong cross-shelf change in euphausiid assemblages located about 45 km from shore. Euphausia pacflca and T. spinfera have life stage-segregated distributions, suggesting active location-maintenance strategies. Morphology and biometry of all the post-spawning embryonic stages and the hatching mechanisms of three broadcast-spawning (E. pacfica, T. spinfera and Thysanoe;sa inspinata) and one sac-spawning (Nematoscelisdjfficilis)euphausiids are described. The average embryo and chorion diameters were significantly larger for E. pacca (0.378,0.407 mm) than for T. spinfera (0.35 3, 0.363 mm) and T. inspinata (0.312, 0.333 mm). There are four hatching mechanisms. Some broadcast-spawning species have delayed hatching schedules, hatching as nauplius 2, metanauplius or calyptopis 1, rather than as the usual nauplius 1. Sac-spawning species sometimes hatch early as nauplius 2, rather than as the normal pseudometanauplius or metanauplius. Late and early hatching schedules were associated with low hatching success and small brood size. The brood sizes (BS) of E. pacca and T. spin(fera were estimated during incubations on 23 cruises. Thysanoessa spinifera had higher BS and extended its spawning areas farther offshore during 2002 than in 1999-2001. Euphausia pacfica had a stable inshore-offshore brood- size pattern from 2001 to 2003, and had greater BS than during 1999-2000. Elevated egg production during summer 2002 was associated with cooler, high chl-a conditions resulting from anomalously high equatorward transport. © Copyright by Jaime Gómez Gutiérrez December 12, 2003 All Rights Reserved Comparative Study of the Population Dynamics, Secondary Productivity, and Reproductive Ecology of the Euphausiids Euphausia pacifica and Thysanoessa spinfera in the Oregon Upwelling Region by Jaime Gómez Gutiérrez A DISSERTATION Submitted to Oregon State University In partial fulfillment of The requirements for the Degree of Doctor Philosophy Presented December 12, 2003 Commencement June 2004 Doctor of Philosophy dissertation of Jaime Gómez Gutiérrez presented on December 12, 2003. APPROVED: Redacted for Privacy Co-major Professor, representing Oceanography Redacted for Privacy ' Co-major Professor, representing Redacted for Privacy Dean of the College of Oceanic and Atmospheric Sciences Redacted for Privacy Dean of tho' Jradóate School I understand that my dissertation will become part of the permanent collection of Oregon State University libraries. My Signature below authorizes release of my dissertation to any reader upon request. Redacted for Privacy Author ACKNOWLEDGEMENTS I have been graced with many excellent people who have helping me along the way. I want to thank my major advisors, Charles B. Miller and William T. Peterson, for their friendship, unconditional support, the freedom in my research, and for the faith they put in me in the last five years. Charlie, your patience and generosity to share your knowledgeand your laboratory space are infinite, thanks for helping me in all my requests. You arethe best teacher I have ever and your research guide was superb and unconditional, youalways gave me a new way to see and solve the scientific problems I faced. I was honored to have a mentor like you. Your patience and help in improving my English and most importantly the ideas included in the thesis, particularly while I was writing the thesis, made it possible for me to defend my thesis on time. Bill, I really appreciate the optimism and confidence you gave me to come to Corvallis to work with you. I enjoyed working in your laboratory in summer 1997 when I started working with live zooplankton. Your unconditional support, your experience and good sense of humor makes you the perfect research advisor. I'm so glad I had the opportunity to be part of your Newport zooplankton research group. I also wish to thank the other members of my Graduate Committee Patricia A. Wheeler, Bruce McCune, and William Warren for their feedback and encouragement through this thesis. I thank Centro Interdisciplinario de Ciencias Marinas (CICIMAR) from the Instituto Politécnico Nacional in La Paz, Baja California Sur (Mexico) for the economical support during my entire PhD program. I particularly thank Victor Manuel Gómez Muñoz, Francisco ArreguIn Sanchez, Ricardo Palomares Garcia, Sergio Hernández Trujillo, Roberto Felix Uraga, and Jose Luis OrtIz Galindo, for their unconditional help with the mountain of paperwork and reports for the Instituto Politécnico Nacional during my work in Oregon. I was also supported by a Sistema Nacional de Investigadores (SNI, 15876), COFAA-IPN fellowship level IV and a Mexican PhD grant from Consejo Nacional de Ciencias y TecnologIa (CONACyT, 122676) tostudy at Oregon State University. This research was partially supported by funds provided by the Office of Naval Research (National Ocean Partnership Program) in 1999-2000, the U.S. GLOBEC NEP (NA860P0589) program in2001-2003,jointly funded by the National Science Foundation and the National Oceanic and Atmospheric Administration, provided ship time and staff assistance, and by two non-consecutive Mamie Markham Research awards from HatfieldMarine Science Center (HMSC, Newport OR). I would like particularly to express my gratitude to Marnie Markham's family for giving me the Markham Research Award during2001-2002and2003-2004.This economical support helped me to purchase critical equipment, supplies and services to complete my experimental work. The significance of this award is that provided me the economical independence that any graduate student needs. I thank the Warren Denner family and the selection of candidates committee for giving me the honor of receiving the Warren W. Denner Memorial Graduate Student Fellowship Award (September 20, 2002). It was an unforgettable surprise that Krista Longnecker conspired to be sure I was there during the COAS meeting award. This research had the input and critics of several creative, ingenious, and professional people that substantially improved the content of each chapter of this dissertation. Therefore I deeply give thanks to Charles B. Miller (COAS), William T. Peterson (NOAA), Margaret Knight (Sb), Edward Brinton (Sb), Annie Townsend (Sb), Alex de Robertis (NOAA), Richard Brodeur (NOAA), Jennifer Cram (COAS), Cheryl Morgan (HMSC), Phillip L. Hertzler (Central Michigan University), Stephen C. Landers (Troy University), Frank J. Morado (NOAA-Seattle), Denis Lynn (University of Guelph), Gerhard Scholtz (Humboldt-Universitaet zu Berlin), Waldo Wakefield (NMFSIHMSC), Masayuki Saigusa (Okayama University), Robin Ross (SBCU), and Jannine Roudy-Cuzin (Observatorire Océanologique, France) for their critical and valuable comments to the original manuscripts. I thank Al Soeldner for his unconditional and proffesional assistance for the SEM micrographs for the chapters 8 and 9. In particular, I wish to thank my 'long-distance advisors' Edward Brinton, Margaret Knight and Annie Townsend for their friendship, the review of the chapters 3 and 4 and unlimited help during all those years I have been studying euphausiids at Baja California and Oregon (circa 1990). All you are a source of inspiration, dedication and certainly an excellent example of the kind of scientists than any graduate student (including myself) would like become some day. This research was possible only because I was lucky to work with bold, friendly and hard working people that apparently enjoy the rough Oregonian sea conditions: I am in debt to my dear friends Leah R. Feinberg, Tracy Shaw, Julie Keister, Anders Roestad, Mitch Vance, and Jesse Lamb from HMSC and the WV Elakha, WV New Horizon and R/V Wecoma crew (particularly Ron Barrell, Perry York, Daryl Swensen, Toby Martin, and Marc J. Willis) and many other for their collaboration in the collection of the live samples between 1999 and 2003. Se-Jong Ju and Rodger Harvey (Cheasapeake Biological Center, University of Maryland Center for Environmental Sciences) gave me all your support and analyzed the lipid composition of the euphausiid eggs that due time constrains were not included in the thesis. Dr. Patricia Wheeler, along her wonderful group of students and technicians, provided the Chl-a data for the L-TOP cruises, and Leah Feinberg, Tracy Shaw and Julie Keister took care of the Chl-a data for the RIV Elakha and Mesoscale cruises used in the chapters 6 and 7 of fecundity of euphausiids and their data of euphausiid dry weight. To my dear office mates and friends Cheryl Morgan, Jennifer Cram,and Marnie Jo Zirbel, I had a great time with all you talking about everything my poor English allows me, your endurance, patience and support and academic experience will never will be forgotten and made every day in the laboratory a fun experience. Irma Delson you are perhaps the most loved