Technical Note—Performance Evaluation of the PhytoFind, an In-Place Phytoplankton Classification Tool

Scientific Investigations Report 2022-5103
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  • Related Work: Techniques and Methods 1-D10 - Field Techniques for the Determination of Algal Pigment Fluorescence in Environmental Waters—Principles and Guidelines for Instrument and Sensor Selection, Operation, Quality Assurance, and Data Reporting
  • Data Releases:
    • USGS data release - Near-surface spatial water-quality surveys along the Caloosahatchee River, St. Lucie River and Lake Okeechobee in July and August 2019, south Florida (ver. 1.1, December 2020)
    • USGS data release - Phytoplankton community composition and abundance in Lake Okeechobee and the Okeechobee Waterway, Florida, USA, July and August 2019
    • USGS data release - Laboratory and field data for an evaluation of the Turner Designs PhytoFind, in situ algal classification tool
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In 2019, the U.S. Geological Survey evaluated the performance of the Turner Designs, Inc. PhytoFind, an in-place phytoplankton classification tool. The sensor was tested with sample blanks, monoculture and mixed phytoplankton cultures, and turbidity challenges in a laboratory, and was tested on a 120-mile survey of the Caloosahatchee and St. Lucie Rivers in Florida, including Lake Okeechobee. Results include the following:

  • The mixed phytoplankton group fluorescence channel (green excitation sensor) of the PhytoFind can be sensitive to interference.
  • The PhytoFind generally overestimated chlorophyll concentration relative to laboratory-measured chlorophyll a concentrations.
  • Turbidity interference may be less apparent in samples where green algae (chlorophytes) represent a high relative percentage of biovolume.
  • The dissolved organic matter compensation feature was effective in the environmental waters sampled during this evaluation.
  • The correlation between percent chlorophyll contribution per phytoplankton group measured by the PhytoFind and relative percent biovolume per phytoplankton group measured in the laboratory varied and was not explicitly determined to be related to dominant taxa, phytoplankton community composition, or environmental conditions.

Suggested Citation

Johnston, B.D., Graham, J.L., Foster, G.M., and Downing, B.D., 2022, Technical note—Performance evaluation of the PhytoFind, an in-place phytoplankton classification tool: U.S. Geological Survey Scientific Investigations Report 2022–5103, 36 p.,

ISSN: 2328-0328 (online)

Table of Contents

  • Abstract
  • Introduction
  • Laboratory Methods To Test PhytoFind Performance
  • Field Methods To Test PhytoFind Performance
  • Results of Laboratory Testing
  • Results of Field Testing
  • Summary
  • Acknowledgments
  • Selected References
Publication type Report
Publication Subtype USGS Numbered Series
Title Technical note—Performance evaluation of the PhytoFind, an in-place phytoplankton classification tool
Series title Scientific Investigations Report
Series number 2022-5103
DOI 10.3133/sir20225103
Year Published 2022
Language English
Publisher U.S. Geological Survey
Publisher location Reston, VA
Contributing office(s) Caribbean Water Science Center, Kansas Water Science Center, New York Water Science Center
Description Report: vi, 36 p.; Data Releases
Online Only (Y/N) Y
Additional Online Files (Y/N) N
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