Landscape Change in Suisun Marsh By AMBER DAWN MANFREE B.A. (Sonoma State University) 1995 M.A. (University of California, Davis) 2012 DISSERTATION Submitted in partial satisfaction of the requirements for the degree of DOCTOR OF PHILOSOPHY in Geography in the OFFICE OF GRADUATE STUDIES of the UNIVERSITY OF CALIFORNIA DAVIS Approved: _____________________________________ Peter B. Moyle, Chair _____________________________________ Deborah L. Elliott-Fisk _____________________________________ Jay R. Lund Committee in Charge 2014 i UMI Number: 3646341 All rights reserved INFORMATION TO ALL USERS The quality of this reproduction is dependent upon the quality of the copy submitted. In the unlikely event that the author did not send a complete manuscript and there are missing pages, these will be noted. Also, if material had to be removed, a note will indicate the deletion. UMI 3646341 Published by ProQuest LLC (2014). Copyright in the Dissertation held by the Author. Microform Edition © ProQuest LLC. All rights reserved. This work is protected against unauthorized copying under Title 17, United States Code ProQuest LLC. 789 East Eisenhower Parkway P.O. Box 1346 Ann Arbor, MI 48106 - 1346 Amber Dawn Manfree September 2014 Geography Landscape Change in Suisun Marsh Abstract Suisun Marsh is a 470 km2 wetland situated between the Sacramento-San Joaquin Delta and San Pablo Bay in the San Francisco Estuary. Today, about 80 percent of the marsh plain is privately owned by duck hunting clubs and managed in accordance with conservation agreements. A complex network of sloughs weaves through the Marsh, providing habitat for numerous aquatic species. Together the waterways and marsh plain support a stunning array of species, provide exurban open space, and are increasingly called upon to meet regional conservation objectives. The Marsh is vulnerable to sea level rise impacts, pollution, and other human impacts, so understanding how it functions so it can be successfully managed to meet the lofty objectives set out for it will be critically important in the decades ahead. This study reviews landscape-scale historical ecology of Suisun Marsh and examines recent variation in fish populations from a geographical perspective. Chapter 1 presents the geomorphic and physical history of the landscape, explaining processes driving wetland development and contributing to unique functional subregions within the Marsh. Chapter 2 examines human- and animal-landscape interactions. Ecologically ii significant shifts in human and animal populations during the Spanish and Mexican eras, followed by agricultural development in the late 1800s and duck club management starting around 1900, have kept the Marsh landscape continually changing. The rate and magnitude of landscape change has intensified since European contact in 1769 and even more since the Gold Rush of 1849. Chapter 3 explores landscape-scale variation in species distribution and abundance based on a long-term study of Suisun Marsh fishes and invertebrates and presents these data in novel animations. Animated maps are used to explore shifting populations of fishes and invertebrates from 1980 to 2013, demonstrating the value of long-term biogeographical datasets in understanding biological communities at the landscape scale. Understanding both the deep and recent history of the Marsh provides insights and inspiration, informs management approaches, points to potential restoration and rehabilitation targets, and affects attitudes about appropriate human interactions with this dynamic biological system and landscape. iii Acknowledgements My heartfelt thanks go out to my committee members who offered consistent, firm, and ever- wise advice. I am fortunate to have benefitted from the technical expertise of professors Peter Moyle, Deborah Elliott-Fisk, and Jay Lund throughout this project. Their scientific conscientiousness is well balanced by their spirited love of life and learning. This work has benefitted tremendously from insights gained through long conversations at all hours with friends Teejay O’Rear, Bethany Hopkins, and Alison McNally. The uncovering of big ideas often starts with tiny hints about which threads to follow and many of these were found in conversations about our converging research interests. Turning up the right historical documents can be a challenge, and cogent advice from Alison Whipple, Chuck Striplen and Robin Grossinger of the San Francisco Estuary Institute was a great help. Fellow geographer Joseph Honton’s historical ecology research in the Laguna de Santa Rosa watershed provided a helpful research template for me to follow, but moreover his meticulous and deeply thoughtful approach to the work itself is a lesson that I will always carry with me. When I first heard tell of the dataset associated with the Suisun Marsh Fish and Invertebrate Study I immediately wanted to animate it, but I had little sense of how to go about it. My cousin Tony MacCabe graciously dedicated time and energy to solving my database management problems, even from the other side of the continent. William Fleenor always seemed to point me in the direction of progress when I thought I had reached a wall, particularly when he introduced me to Steven Micko at just the right moment to assist with approximating the effects of the Suisun Marsh Salinity Control Gates on flow and salinity. iv Several good ideas about data products and how to share them came from Nick Santos, and enthusiastic feedback from the cadre of fisheries biologists at the Moyle Lab kept me excited about this project throughout. John Durand and Denise DeCarion in particular were always available to answer my questions about basic fish ecology, and, if my questions were elementary, they were polite enough not to let on. The greatest champion of Geography at UC Davis is probably Carrie Armstrong-Ruport, the Student Affairs Officer for the Geography Graduate Group. In my eight years at UC Davis I have seen her outlast numerous chairs and deans and even a chancellor, all the while deftly lending students logistical and moral support and doing whatever it takes to keep the graduate group healthy and vibrant. I began benefitting from her ability even before I turned in my application for admission and will no doubt continue to benefit from the reputation of the graduate group, which she has helped to cultivate, throughout my career. Thanks Carrie. Geographers would be lost without you. The many affiliates and employees of the Center for Watershed Sciences at UC Davis and the John Muir Institute for the Environment have helped me smoothly maneuver through my final years in graduate school. Barbara Bellieu and Cathryn Lawrence in particular have helped me solve problems big and small. I offer many thanks to my family for their patience and support throughout my academic career, which has turned out to be much longer than any of us expected. I gratefully acknowledge the funding for this work provided to the Center for Watershed Sciences by the S. D. Bechtel, Jr. Foundation for the “Delta Solutions” and “Integrated v Management of California’s Water Resources” programs and by the California Department of Fish and Wildlife’s Ecosystem Restoration Program (Grant #E1183013). Davis, California August 2014 vi Chapter 1 Physical Processes Shaping Suisun Marsh Introduction Suisun Marsh, a wetland located between San Pablo Bay and the Sacramento-San Joaquin Delta in California (figure 1.1), is a place of constant and relatively rapid change, with vital connections to regional ecological processes. Natural forces, such as faulting, winds, tides and river flows have sculpted this wetland landscape over the past 6,000 years. Telltale signs of geomorphic processes are now largely obscured by human modifications; nevertheless, by comparing maps made at different times, drivers of change can be seen in the patterns that emerge, helping to infer processes. Novelties and subtleties of landscape ecology are often found in historic accounts, and tracking landscape change through time can aid both likely current and future management practices. High-energy drivers such as tides, great rivers, and winds have sustained constant and relatively rapid geomorphic and ecological change throughout the 6,000-year history of the Marsh. Geology, tectonics, and geomorphology About 25 mya1, the Pacific Plate met the North American Plate and began to slide north- northwestward. Ten million years later, this transformational boundary reached the area that would become the San Francisco Estuary. By 3.5 mya, contact between plates changed from 1 Mya = million years ago. 1 Figure 1.1. Location of Suisun Marsh in relation to San Pablo Bay and the Sacramento- San Joaquin Delta (CalAtlas 2012). Non-tidal wetland areas shown in pale green; tidal wetlands shown in dark green (SFEI 2012). plates sliding past one another to plates sliding at an angle relative to one another, a combination of sliding and compression termed “transpression.” The resulting increase in friction initiated the rise of the Sierra Nevada. About two million years later, these same forces began to lift the Coast Ranges that frame the San Francisco Estuary we know today. The Coast Ranges on the North American Plate were pulled and stretched by the Pacific Plate in a north- northwesterly direction relative to the Central Valley, a process that continues today. Although all of the Coast Ranges move in the same general direction, westward segments move relatively 2 faster than eastward ones. Thus the San Francisco Estuary landscape has been, and continues to be, rapidly reconfigured – at least in geologic time (Sloan 2006). The estuary is geologically young, having changed dramatically over the past one million years. The Central Valley of one mya was a large inland lake and what is now the floor of San Francisco Bay was a plain crossed by small rivers. Around 620,000 years ago, this configuration shifted. The inland lake began draining to the Pacific by down-cutting the present Sacramento River channel that passes by Suisun Marsh and then flowing through Carquinez Strait and into San Francisco Bay. Much later, during the ice age about 20,000 ybp, sea level was lower and the ocean shoreline was situated nearly 50 km (30 mi) west of the Golden Gate. At this time, California’s greatest river meandered between floodplains that now lay beneath San Pablo and San Francisco bays (Sloan 2006). The valley in which Suisun Marsh formed was created by tectonic activity along the Concord-Green Valley Fault System, as well as by smaller nearby faults. A series of northwest- southeast trending anticlines and synclines undulate to depths up to 2,500 meters beneath the peat soils and alluvium of the eastern Marsh and Grizzly, Suisun and Honker bays. These anticlines and synclines are underlain by southwest-dipping thrust faults (Unruh and Hector 2007). The Potrero Hills are comprised of Tertiary rocks uplifted by an anticline; the Montezuma Hills are made of younger alluvial deposits that also have been uplifted (Sloan 2006). Approximately 10,000 years ago, sea level was still much lower than it is today. At this time, the Suisun Marsh region was a river valley. Sea level rose as glaciers melted in the Earth’s warming climate and fringing marshes advanced upslope as the bays filled with water (Atwater 3