First Advisor

Anne W. Thompson

Date of Award

Spring 6-2025

Document Type

Thesis

Degree Name

Bachelor of Science (B.S.) in Biology and University Honors

Department

Biology

Language

English

Subjects

Willamette, synechococcus, diatom, qPCR, flow cytometry, image cytometry

Abstract

Waterways that support human society and life on Earth host superabundant microorganisms which support all ecosystems and food webs: phytoplankton. This study aimed to identify and quantify phytoplankton in the Willamette River in order to understand the dynamics between different phyla. Building on previous studies, which showed that communities of phytoplankton change with the river environment, this work determined how eukaryotic and prokaryotic phytoplankton vary with one another while inhabiting the same river conditions. The approach involved sampling the Willamette river over a weekly time series and combined analytical techniques of qPCR, flow cytometry, and image cytometry to assess population composition and dynamics. The outcome provided a better understanding of causes and effects of changing community dynamics in a river. Combining qPCR, flow cytometry, and image cytometry revealed phytoplankton community structure more than any single approach could. Diatoms and subpopulations of picocyanobacteria were found to share correlations in community dynamics. Phycocyanin-producing organisms could be a major influence of the broad phytoplankton community. This work will generate hypotheses towards improved understanding of phytoplankton in river systems.

Comments

An undergraduate honors thesis submitted in partial fulfillment of the requirements for the degree of Bachelor of Science in University Honors and Biology: Microbiology.

Persistent Identifier

https://archives.pdx.edu/ds/psu/43135

Included in

Biology Commons

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