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Date Permissions Signed


Date of Award

Summer 2020

Document Type

Masters Thesis

Degree Name

Master of Science (MS)



First Advisor

Moyer, Craig L.

Second Advisor

Arellano, Shawn M.

Third Advisor

Schwarz, Dietmar, 1974-


Crater Lake, Oregon is an oligotrophic freshwater caldera lake fed by thermally and chemically-enriched hydrothermal springs. These vents distinguish Crater Lake from other freshwater systems and provide a unique ecosystem for study. This study examines the microbial community structure of hydrothermal mat communities found in the bottom of Crater Lake. Small subunit rRNA gene amplicon sequencing from eight microbial mats was used to assess community structure. These findings revealed a relatively homogeneous, yet diverse bacterial community. High alpha diversity and low beta diversity indicates that these communities are likely fueled by homogeneous and consistent hydrothermal fluids. An examination of autotrophic taxa abundance revealed the potential importance of reduced iron and sulfur inputs to the primary productivity of these mats. Chemoautotrophic potential within the mats was dominated by iron oxidation from Gallionella and Mariprofundus and by sulfur oxidation from Sulfuricurvum and Thiobacillus with an additional contribution of nitrite oxidation from Nitrospira. These data link the importance of the detected autotrophic metabolisms driven by fluids derived from benthic hydrothermal springs to Crater Lake’s entire lentic ecosystem.




chemoautotroph, microbial, crater, lake, mat, benthic, hydrothermal, spring, ecology, amplicon


Western Washington University

OCLC Number


Subject – LCSH

Microbial mats--Oregon--Crater Lake; Freshwater organisms--Oregon--Crater Lake; Hydrothermal vents--Oregon--Crater Lake; Freshwater biology--Oregon--Crater Lake

Geographic Coverage

Crater Lake (Or.)




masters theses




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