Graduation Date

Spring 2023

Document Type



Master of Science degree with a major in Biology

Committee Chair Name

Catalina Cuellar-Gempeler

Committee Chair Affiliation

HSU Faculty or Staff

Second Committee Member Name

Will Ryan

Second Committee Member Affiliation

Community Member or Outside Professional

Third Committee Member Name

Jianmin Zhong

Third Committee Member Affiliation

HSU Faculty or Staff

Fourth Committee Member Name

Paul Bourdeau

Fourth Committee Member Affiliation

HSU Faculty or Staff


Microbial ecology, Estuarine anemones, Host-microbe interactions, Invasion ecology, Microbiome, Community ecology, Temperature, Biogeography, Diadumene lineata, Diadumene leucolena, Metridium senile, Pseudoalteromona

Subject Categories



Non-native species are increasing in prevalence around the world, resulting in negative economic and ecological impacts. However, the broad distributions of non-native species also offer a system for investigating the response of host-associated microbial communities to environmental factors across a range of ecological scales. At the broadest scale, I investigated the geography of microbial communities in the non-native estuarine anemone Diadumene lineata on the west coast of the United States of America. Across latitudes, microbial community composition was very similar and displayed a high percentage of Klebsiella spp. at all sites. However, the communities in California tended to exhibit higher richness, Shannon-Wiener diversity, and beta-dispersion than the communities in Oregon and Washington, driven by an abundance of Desulfobacterota. In a stress experiment, where three anemone species (Diadumene lineata, Diadumene leucolena, and Metridium senile) were subjected to a gradient from 0-40°C to evaluate each species’ capacity for buffering their microbial community against thermal stress, I found species-specific patterns across temperatures, with only M. senile exhibiting evidence of buffering at moderate temperatures. In contrast, D. lineata and D. leucolena did not appear to be buffering their microbial communities, with D. lineata displaying unique community compositions across temperatures, while the communities on D. leucolena generally exhibited high beta-dispersion. Finally, I isolated anemone-associated bacteria on a novel medium made of anemone tissue and measured their growth from 30-40°C, identifying candidates for beneficial host-microbe interactions in warm environments. The anemone-based medium overwhelmingly selected for the genera Pseudoalteromonas and Peribacillis, regardless of anemone host species. Peribacillus spp. were particularly thermal tolerant, growing similarly from 30-40°C, while Pseudoalteromonas spp. grew well from 30-35°C. The remaining tested genera preferred 30°C, however one of the Litoreibacter sp. produced a putative melanin that may protect cells against thermal stress. This is the first study exploring microbial communities in the non-native estuarine anemone D. lineata and lays the foundation for an expanded global assessment of latitudinal gradients, investigating how additional abiotic factors like genotype and pH drive microbial community composition, and directly testing beneficial host-microbe interactions with isolated bacteria.

Citation Style




To view the content in your browser, please download Adobe Reader or, alternately,
you may Download the file to your hard drive.

NOTE: The latest versions of Adobe Reader do not support viewing PDF files within Firefox on Mac OS and if you are using a modern (Intel) Mac, there is no official plugin for viewing PDF files within the browser window.