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Date of Award

Fall 2025

Document Type

Masters Thesis

Department or Program Affiliation

Biology

Degree Name

Master of Science (MS)

Department

Biology

First Advisor

Moyer, Craig L.

Second Advisor

Schwarz, Dietmar, 1974-

Third Advisor

Brodhagen, Marion (Marion L.)

Abstract

Microbial mat communities are prevalent across deep-sea hydrothermal regions, providing chemolithoautotrophy that drives greater ecosystem development. Despite their ubiquity, connectivity and succession of these microbial communities are poorly understood. Capitalizing on the frequent sampling effort of the New Millenium Observatory (NeMO) expeditions, this study assessed SSU rRNA taxonomic composition of 37 microbial mat communities from a diverse range of habitats around Axial Seamount following a major eruption. This included four- and five- year repeated samplings of two communities developing within the newly deposited lava flows, representing one of the longest observations of microbial mat succession in a deep-sea hydrothermal ecosystem. Microbial mat communities across the Seamount presented varying degrees of similarity, manifesting into four hierarchical clusters that provide insight into thresholds of hydrothermal vent microbial taxonomic composition. Three of these clusters were spatially and temporally heterogenous, indicating environmental conditions and stochasticity may play a major role in community structure in these habitats. While most communities were dominated by Campylobacterota, they were differentiated by extensive diversity at lower taxonomic levels. Most prevalent were the sulfur- and hydrogen-oxidizing Sulfurovum and Sulfurimonas, which appeared to fluctuate independently despite little known separation in the metabolic abilities of cultured representatives from these genera. Indicator ASVs were found in association with each of the four clusters, helping identify potentially deterministic microbial mat community members and combinations of taxa that may serve as “fingerprints” of community structure. This includes the iron-oxidizing Zetaproteobacteria, which appeared exclusively in communities presenting high ASV richness and diminished Campylobacterota abundance. This study establishes one of the broadest taxonomic surveys of microbial communities across an active seamount, providing essential direction for a future metagenomics investigation at Axial Seamount.

Type

Text

Keywords

Microbial Ecology, Hydrothermal Vent, Microbial Mat, Campylobacterota, Sulfurovum, Sulfurimonas, Axial Seamount, Community Ecology

Publisher

Western Washington University

OCLC Number

1551320153

Subject – LCSH

Microbial ecology--Axial Seamount; Hydrothermal vent ecology--Axial Seamount; Microbial mats--Axial Seamount; Biotic communities--Axial Seamount

Geographic Coverage

Axial Seamount

Format

application/pdf

Genre/Form

masters theses

Language

English

Rights

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.

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