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

Fall 2022

Document Type

Masters Thesis

Department or Program Affiliation

College of Environmental Science, Marine and Estuarine Science Program

Degree Name

Master of Science (MS)


Environmental Sciences

First Advisor

Bingham, Brian L., 1960-

Second Advisor

Brooke Love

Third Advisor

Love, Brooke


The Salish Sea, a large and complex fjord estuary, receives waters impacted by a watershed that includes 8 million people aggregated in several large urban and industrial centers. Microplastics, defined as plastic particles less than 5 mm in their largest dimension, are transported from this watershed into the Salish Sea where they are easily ingested by filter feeders, herbivores and predators. To measure effects of microplastics on one common and important intertidal species, we exposed the sea anemone Anthopleura elegantissima to polyester microfibers at concentrations of 0, 0.01, or 0.1 g/L in the laboratory and measured the responses of the anemones throughout a 38-day exposure period. Because A. elegantissima hosts photosymbionts, we hypothesized that microplastics could affect the host, the symbiont, or both and took measurements to evaluate performance of both the hosts and the symbionts. We used linear mixed model analyses to evaluate changes in anemone size via oral disc diameter, digestive efficiency, and respiration rate, and to measure effects to symbionts we measured photosynthetic efficiency (Fv/Fm), symbiont density, and symbiont mitotic index. We interpret the effects of the microplastic exposure against the background effect of the environmental changes experienced through our experiment and found that smaller anemones had lowered digestive efficiencies in high microplastic concentrations, and that photosymbionts seem to play a minor role in the success of the anemone in the presence of microplastics when looking at Fv/Fm over time and anemone size over time. The results suggest that, under the experimental conditions we used, the short-term effects of microplastic exposure on A. elegantissima are not large. However, microplastics could have more lasting impacts over time that could affect the success of this species living in seas already impacted by other environmental stressors including rising temperatures, acidification, and chemical pollutants.




microplastic, exposure, responses, intertidal, anemone, Anthopleura elegantissima, experiment, polyester, microfiber, respiration, oral disc diameter, digestive efficiency, symbiosis, fv/fm, mitotic index, symbiont cell density


Western Washington University

OCLC Number


Subject – LCSH

Microplastics--Environmental testing--Salish Sea (B.C. and Wash.); Anthopleura--Effect of contaminated sediments on--Salish Sea (B.C. and Wash.); Estuarine ecology--Salish Sea (B.C. and Wash.)

Geographic Coverage

Salish Sea (B.C. and Wash.)




masters theses




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.

Rights Statement

Creative Commons License

Creative Commons License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License.