Date of Award

2018

Degree Type

Thesis

Degree Name

Master of Science in Oceanography

Department

Oceanography

First Advisor

Melissa Omand

Abstract

Achieving depth-resolved particle-specific data in sparse, highly variable oceanic environments persists as a methodological challenge. Holography has emerged as a tool for in-situ imaging of microscopic organisms and other particles in the marine environment; appealing because of the relatively larger volume and simple optical configuration compared to other imaging systems. The digital in-line holographic microscope (DIHM) used in this study samples ~100× larger volumes than comparable objective lens-based systems, and is deployable on CTD-rosette, flow-through, and autonomous systems. However, it’s quantitative capabilities have so far, remained uncertain. Here, the quantitative skill of the DIHM to evaluate size and concentration of marine particles ranging from 5 to 1000 μm in diameter is assessed. Over one million particles are analyzed using a custom image processing pipeline, which allows a precise characterization of the three-dimensional volume sampled. These results are compared with the FlowCam, the Imaging FlowCytobot and traditional microscope counts through laboratory and field-based inter-calibration experiments. Based on this analysis, recommendations for achieving quantitive size and concentration measurements from the DIHM are suggested.

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