Date of Award

2017

Degree Type

Thesis

Degree Name

Master of Science in Oceanography

Department

Oceanography

First Advisor

Rebecca Graham

Abstract

Diatoms are important ecologic indicators whose assemblage, chemistry, and valve features are reflections of their original environmental conditions. Fossil diatom biometrics are an emerging measurement introduced to supplement our understanding of the hydrographic history of the Southern Ocean. Here, we present a novel method to simultaneously measure fossil diatom assemblage and biometrics using a FlowCam, an instrument combining features from a flow cytometer and microscopic camera. It offers, computerized automatic identification to supplement manual, visual identifications, leading to increased counts and biometric measurements. To assess the viability of the FlowCam as a paleoceanographic tool, a FlowCam measured data set was compared to previously published diatom assemblage and biometric data generated by traditional microscopic methods from a Southern Ocean sediment core. Diatom assemblages and the biometric lengths of Fragilariopsis kerguelensis measured with the FlowCam showed similar trends to those produced by traditional microscopy. The biggest difference was the relative occurrence of Eucampia antarctica, which was observed more frequently using the FlowCam. The high biometric data output from the FlowCam was used to determine an empirically derived, minimum sample count and confidence intervals for future best practices.

Available for download on Saturday, July 28, 2018

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