engleski

Assessment of holographic microscopy for quantifying marine particles

Characterizing marine snow and phytoplankton communities in sparse, highly variable oceanic environments remains a methodological challenge. In situ holography may help to address this challenge by sampling 100x larger volumes than comparable objective lens-based systems, and is easily deployable on CTD- rosette, flow-through, and autonomous systems. Qualitatively, detected particle counts show good agreement with beam attenuation down to depths of 1000m (the depth rating of our autonomous system). Here, the quantitative capability of a digital in-line holographic microscope to evaluate abundance, size and type of particles ranging from 5 to 1000 micron equivalent spherical diameter, is assessed. Over one million particles are analyzed using a custom image processing pipeline, which allows a precise definition of the three-dimensional volume sampled. Experiments were performed on dilutions of Dunaliella culture and with environmental samples collected from the North Pacific in February 2017 and compared with concentration estimates from an Imaging FlowCytobot, FlowCam, and manual light microscope counts. The good correlation (r2 = 0.92, P < 0.05) with these other detection methods suggests that digital holography is a promising tool for in situ and autonomous studies of ocean biogeochemical cycling and phytoplankton ecology.

phytoplankton, hographic microscope, method comparisson

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