Date of Award

Spring 1-1-2014

Document Type


Degree Name

Master of Science (MS)

First Advisor

Diane McKnight

Second Advisor

Sarah Spaulding

Third Advisor

Daniel F. Doak


The nuisance diatom Didymosphenia geminata has received much attention in the last 25 years, but little is known about its population growth and reproductive dynamics. In this study, I examined the size structure of discrete populations of D. geminata over a 13-month period at South Boulder Creek (Boulder County, Colorado.) My objective was to clarify temporal patterns in cell size frequency, size restoration strategy, and potential life cycle coordination between nearby populations. Cell size was measured using FlowCAM imaging particle analysis and analyzed using finite mixture models.

This study is the first to document the complexity of diatom cell size distribution in a lotic system, size restoration in D. geminata, and the variability in rates of size reduction among different habitats. These results firmly demonstrate the benefits of FlowCAM analysis and mixture modeling in diatom size reduction studies, having accumulated cell counts far outnumbering all previous diatom life history studies.