The vast majority of theses in this collection are open access and freely available. There are a small number of theses that have access restricted to the WWU campus. For off-campus access to a thesis labeled "Campus Only Access," please log in here with your WWU universal ID, or talk to your librarian about requesting the restricted thesis through interlibrary loan.
Date Permissions Signed
Date of Award
Department or Program Affiliation
Marine and Estuarine Science Program-Department of Environmental Science
Master of Science (MS)
Bingham, Brian L., 1960-
Strom, Suzanne L., 1959-
Dimond, James L.
Ocean acidification (OA) threatens many marine species and is projected to become more severe over the next 50 years. Areas of the Salish Sea and Puget Sound that experience seasonal upwelling of low pH water are particularly susceptible to even lower pH conditions. While ocean acidification literature often describes negative impacts to calcifying organisms, including economically important shellfish, and zooplankton, not all marine species appear to be threatened by OA. Photosynthesizing organisms, in particular, may benefit from increased levels of CO2.
The aggregating anemone (Anthopleura elegantissima), a common intertidal organism throughout the northeast Pacific, hosts two photosynthetic symbionts: Symbiodinium muscatinei (a dinoflagellate) and Elliptochloris marina (a chlorophyte). The holobiont, therefore, consists of both a cnidarian host and a photosymbiont that could be affected differently by the changing levels of environmental CO2. To determine the effects of OA on this important marine organism, A. elegantissima in each of four symbiotic conditions (hosting S. muscatinei, hosting E. marina, hosting mixed symbiont assemblages, or symbiont free) were subjected to one of three pCO2 levels (800 ppm, 1200 ppm, or 1800 ppm) of OA for 10 weeks. At regular intervals, gross photosynthesis and density of the symbionts, respiration rate of the hosts, levels of reactive oxygen species (ROS) in the host, and percent of organic carbon received by the host from the symbiont (CZAR) were measured. Over the 10-week period of the experiment, the densities of symbionts responded differently to an increase in pCO2, increasing in anemones hosting S. muscatinei but decreasing for those hosting E. marina. Similarly, anemones of mixed symbiont complement that started with approximately 50% of each symbiont type shifted toward a higher percentage of S. muscatinei with higher pCO2. Both gross photosynthesis and dark respiration were significantly affected by pCO2 and symbiont state, though we cannot say that the symbionts responded differently to increased OA. Symbiont state was a significant predictor for ROS concentration, with greatest levels seen in anemones hosting E. marina and for CZAR score, with greatest levels in anemones hosting S. muscatinei, our linear models did not reveal pCO2 as a significant factor in these responses. Together, these results suggest that S. muscatinei may benefit from elevated pCO2 levels and that A. elegantissima hosting that symbiont may have a competitive advantage under some future scenarios of ocean acidification.
Ocean Acidification, Anemones, Symbiosis, ROS, Photosynthesis
Western Washington University
Subject – LCSH
Sea anemones--Salish Sea (B.C. and Wash.); Ocean acidification--Salish Sea (B.C. and Wash.); Photosynthesis--Salish Sea (B.C. and Wash.); Symbiosis--Salish Sea (B.C. and Wash.)
Salish Sea (B.C. and Wash.)
Copying of this document in whole or in part is allowable only for scholarly purposes. It is understood, however, that any copying or publication of this document for commercial purposes, or for financial gain, shall not be allowed without the author’s written permission.
Creative Commons License
This work is licensed under a Creative Commons Attribution-No Derivative Works 4.0 License.
Coleman, Natalie, "Partner preference in the intertidal: possible benefits of ocean acidification to sea anemone-algal symbiosis" (2021). WWU Graduate School Collection. 1015.