The merit of the Secchi Disk as a qualitative indicator of the deep chlorophyll max depth

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Abstract/Contents

Abstract: This study observes the merit of the Secchi disk as a qualitative indicator of the deep chlorophyll max depth in the open ocean. Fifty percent of global productivity—and nearly all marine productivity—is caused by phytoplankton, and there is great interest in measuring the abundance of phytoplankton in the ocean. In July 2010, Boyce et al. published a study in Nature magazine which claimed that phytoplankton has been undergoing a century-long decline of ~1% a year. However, responses in the scientific community regarding data bias in the Secchi data used by Boyce et al. to support their conclusion have since sparked interest in Secchi’s ability to estimate the deep chlorophyll max depth. The objective of this study is to compare Secchi data against several other mechanisms used to quantify the chlorophyll concentration in the oceans. Along the 2011 cruise track of the SSV Robert C. Seamans, hydrocasts were deployed alongside the Secchi disk and data collected from these efforts have supported the hypothesis that Secchi is a qualitative indicator of the deep chlorophyll max depth (R2 = .675). However, it is not a good indicator of surface primary production (R2 = .377). The research done here is still preliminary, and while it demonstrates the capacity of Secchi as an estimator of the 1% light penetration depth, it cannot be used to make a larger statement about the phytoplankton abundance in the ocean or about the data bias that informs such a conclusion.

Type of resource	text
Date created	June 12, 2011

Author	Dong, Nghi Huynh

Subject	Stanford@SEA
Subject	S-235
Subject	Hopkins Marine Station
Subject	Department of Biology
Subject	Department of Earth System Science
Subject	BIOHOPK 182H
Subject	BIOHOPK 323H
Subject	EARTHSYS 323
Subject	ESS 323
Subject	Secchi Disk
Subject	chlorophyll max depth
Genre	Student project report

Location	https://purl.stanford.edu/gv732wh5892

Use and reproduction: User agrees that, where applicable, content will not be used to identify or to otherwise infringe the privacy or confidentiality rights of individuals. Content distributed via the Stanford Digital Repository may be subject to additional license and use restrictions applied by the depositor.
License: This work is licensed under a Creative Commons Attribution 3.0 Unported license (CC BY).

Preferred Citation: Dong Nghi Huynh, 2011. The merit of the Secchi Disk as a qualitative indicator of the deep chlorophyll max depth. Unpublished student research paper, S-235, Stanford@SEA, Stanford Digital Repository. https://purl.stanford.edu/gv732wh5892.

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