King County’s marine offshore water quality monitoring program collects data on the physical, chemical, and biological characteristics of marine waters within the boundaries of King County. These data are used to improve our understanding of ecosystem structure and function and for assessing potential impacts of human activities, such as from wastewater treatment plant, combined sewer overflow, and stormwater discharges. The phytoplankton monitoring component of this program collects information on phytoplankton community composition, abundance, and biomass. This effort began in 2008 with semi-monthly or monthly assessment of relative abundance metrics for phytoplankton taxa at three sites using microscopy. In May 2014, analysis with a new particle imaging analyzer (FlowCAM®, Fluid Imaging Technologies) was added to the program to analyze samples semi-monthly or monthly from eight sites. This method quantifies both abundance and a proxy of phytoplankton biomass.

This document provides the plan for implementing the marine phytoplankton monitoring program and includes background information, program objectives, sampling design, sample collection and analysis protocols, and data management procedures for this program.