Date of Award

Fall 2020

Date Available to Non-EWU Users


Document Type


Degree Name

Master of Science (MS) in Biology




For freshwater ecosystems, invasive species are considered a major threat to biodiversity, and pose a challenge to those attempting to advance management strategies aimed at conserving natural populations. An invasive species’ ability to successfully invade a new ecosystem may be influenced by phenotypic plasticity, flexibility of life history traits, and the ability to migrate/disperse, among other factors. Brook stickleback (Culaea inconstans) have been a concern in eastern Washington since 1999 when they were discovered in water bodies on Turnbull National Wildlife Refuge. The purpose of this project was to describe potential variation in body morphology traits between systems that differed in environmental factors. BSB were collected at sites throughout the Rock Creek drainage along with environmental measures. Brook stickleback showed variation for all morphology measures between sites (p<0.0001). Lentic and lotic systems expressed difference in a variety of traits (head depth, eye diameter, pelvic spine length, and anal spine length (p<0.00455). Permanent and non-permanent systems expressed differences in weight, standard length, body depth, head length, head depth, eye diameter, gape width, and dorsal spine length (p<0.00455). These results may lay the groundwork for future studies that may determine with more certainty how traits are changing and how quickly.