Experimental Investigation of Tidal and Freshwater Influence on Symbiodiniummuscatinei Abundance in Its Host, Anthopleura Elegantissima
Total Page:16
File Type:pdf, Size:1020Kb
EXPERIMENTAL INVESTIGATION OF TIDAL AND FRESHWATER INFLUENCE ON SYMBIODINIUMMUSCATINEI ABUNDANCE IN ITS HOST, ANTHOPLEURA ELEGANTISSIMA A Thesis submitted to the faculty of San Francisco State University Z o lQ In partial fulfillment of the requirements for H A t X the Degree Master of Science In Marine Science by Daniel John Hossfeld San Francisco, California May 2019 Copyright by Daniel John Hossfeld 2019 CERTIFICATION OF APPROVAL I certify that I have read Experimental investigation of tidal and freshwater influence on Symbiodinium muscatinei abundance in its host, Anthopleura elegantissima by Daniel John Hossfeld, and that in my opinion this work meets the criteria for approving a thesis submitted in partial fulfillment of the requirement for the degree Master of Science in Marine Science at San Francisco State University. Sarah Cohen, Ph.D. Professor Lorraine Ling, Ph.D. Postdoc Researcher at Stanford University EXPERIMENTAL INVESTIGATION OF TIDAL AND FRESHWATER INFLUENCE ON SYMBIODINIUMMUSCAT1NEI ABUNDANCE IN ITS HOST, ANTHOPLEURA ELEGANTISSIMA Daniel John Hossfeld San Francisco, California 2019 Controlled experiments testing effects of temperature, salinity, and aerial exposure were paired with field observations to investigate symbiont expulsion in the abundant intertidal anemone, Anthopleura elegantissima. In the study region, A. elegantissima hosts a single symbiont, the dinoflagellate Symbiodinium muscatinei. The San Francisco Bay outflow creates a tidally influenced low-salinity plume that impacts adjacent coastal sites. Salinity, temperature, and aerial stress induce a bleaching response similar to corals where symbionts are expelled, causing further energetic stress. Using field observations of environmental conditions and symbiont abundance at sites on a gradient of exposure to estuarine outflow, along with fully crossed multifactorial lab experiments, we tested for changes in symbiont abundance in response to various combinations of three stressors. Lab experiments were designed to mimic short term outflow events with low salinity, high temperature, and aerial exposure treatments. The aerial exposure treatment was a statistically significant factor in suppressing symbiont repopulation (ANOVA, p=0.017). Symbiont density decreased with increasing tidal height (ANOVA, p=0.036), suggesting that aerial exposure may affect symbiont density more than sea surface temperature and salinity. Unanticipated documentation of survival in 9 months of sand burial and subsequent repopulation of symbionts is reported in comparison to results from past observations. The study of this symbiosis is useful in examining predicted changes in ocean conditions in tidepool communities. I certify that the Abstract is a correct representation of the content of this thesis. Chair, Thesis Committee Date PREFACE AND/OR ACKNOWLEDGEMENTS Thank you to Dr. Sarah Cohen and fellow Cohen lab students for assistance in fieldwork, wet lab, and logistical planning. Dr. Lorraine Ling assisted with flow cytometry and statistical analyses. Dr. Ed Carpenter, Dr. Frances Wilkerson, and Dr. Colin Leasnre shared expertise in developing methods. Dr John Pringle and lab offered generous use and training on the flow cytometer Dr Phil Cleves assisted with statistical analysis design, Mattie Mrlik assisted with initial laboratory work through the Vassar Internship Grant Fund. Gabe Edralin provided critical field assistance. Thanks to Steve Hossfeld and Jackson’s Hardware for controlled facility design. This project is partially funded by awards to DH from the Dr. Earl H. Myers and Ethel M. Myers Oceanographic and Marine Biology Trust, The SFSU Rosenblatt Award, The SFSU Romberg Tiburon Center Award, and the SFSU Institutional Research Award. Collections and surveys were carried out under California Department of Fish and Wildlife (Permit #1042178169) and National Park Service (Permit GOGA-2017-SCI- 0025) Permits. Thanks to Darren Fong (NPS) for facilitating access to NPS sites. Thank you to Audriana Ossenberg for support, advice, field work assistance, rent subsidies, and reminders to walk away once in a while. Th;* thesis wouldn’t exist in the same capacity without her. The same can be said for Steve and Beth Hossfeld, thank you for many free dinners and advice. TABLE OF CONTENTS List of Tables..........................................................................................................................viii List of Figures ......................................................................................................................ix Introduction............................................................................... 1 Materials and Methods...............................................................................................................6 Results....................................................................................................................................... 11 Discussion............................................................ ’................................................................... 13 References ,28 LIST OF TABLES Table Page 1. Experimental design for wet lab treatments......................................................... 19 2. ANOVA results for Experiment 1 ....................................................................... 20 3. ANOVA results for Experiment 2.........................................................................20 viii LIST OF FIGURES Figures Page 1. Map of field sites,..................................................................................................21 2. Field sampling protocol........................................................................................22 3. Treatment setup for Experiment 1....................................................................... 23 4. Treatment setup for Experiment 2.......................................................................23 5. Salinity and Temperature at the Fort Point Buoy................................................ 24 6. Symbiont density compared across tidal heights................................................ 24 7. Symbiont density at Point Bonita.......................... 25 8. Symbiont repopulation after burial at Mile Rock................................................ 25 9. Experiment 1 results............................................................................................. 26 10. Experiment 2 results............................................................................................. 26 11. Experiment 2 results by treatment....................................................................... 27 1 Introduction Marine organisms living in the rocky intertidal zone are known to be hardy when coping with multiple stressors, but a changing climate is altering life even for the most robust species. The rocky intertidal zone is an accessible marine habitat with a history of studies comparing population dynamics to changing ocean conditions (Sanford et al 1999, Sanford et al 2008, Sagarin et al 2009, Harley 2011, Jeuterbock 2013). Recent studies show climate change impacts on communities of intertidal marine invertebrates, especially considering cascading effects from altered temperature regimes in both water and air (Barry et al 1995, Helmuth et al 2002. Walther et al 2002, Helmuth et al 2006, Hawkins et al 2008, Miekowska 2008. Wetliey et al 2011). Zonation within the intertidal is described by regions across vertical height ranges that are stratified due to temporal variation of aerial exposure at low tide. Organisms at higher vertical zones experience more exposure which can alter body temperature, water temperature, desiccation time or salinity in isolated pools. Altered coastal freshwater inpul as a result of climate change can also affect organisms - for example, rocky intertidal predators such as sea stars are forced to alter behavior during high freshwater input to avoid exposure (Garza & Robles 2010). Freshwater input can occur from nearby coastal runoff due to snowmelt, precipitation, groundwater and sewage export. In tidepools, precipitation can also directly affect the salinity due to rainfall while the pool is exposed (Witman & Grange 1998). 2 Study system The aggregating anemone Anthopleura elegantissima (Cnidaria; Anthozoa) harbors Symbiodinium similar to many reef-building corals. Information on the symbiotic relationships between cnidarians and Symbiodinium species is crucial to understanding the implications of the ongoing widespread coral bleaching events, leading to death of many reefs worldwide. This study provides a temperate intertidal example of altered host-symbiont interactions under varied and multifactorial stresses related to anticipated coastal climate change. It further provides foundational knowledge for the potential of niche construction in the symbiosis between S. muscatinei and A. elegantissima (e.g. following Moczek et al 2015). Anthopleura elegantissima is a commonly observed, abundant rocky intertidal organism found on the eastern boundary of the Pacific from Alaska to Baja California. This species can reproduce asexually (clonal fission) and sexually (broadcast spawning). Anthopleura elegantissima maintains a symbiotic relationship with up to two species of photosynthetic algae that live and reproduce within the tentacles, providing 13 to 45% of the energy in the anemone’s diet and altering its behavior (Fitt 1982, Pearse 19741, Pearse 19742, Bingham et al 2014). In rocky intertidal habitats near the San Francisco