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Date Permissions Signed


Date of Award


Document Type

Masters Thesis

Degree Name

Master of Science (MS)


Environmental Sciences

First Advisor

Matthews, Robin A., 1952-

Second Advisor

Bodensteiner, Leo R., 1957-

Third Advisor

Blinn, Dean W.


I sampled forty lakes in the Puget Sound region of northwest Washington to investigate the relationship between water quality, site characteristics, and algal composition. Water samples were collected during the summer of 2008 to measure nutrients, alkalinity, chlorophyll-a, dissolved oxygen, specific conductance, and temperature. Watershed characteristics were recorded to assess shoreline composition and dominant land use. Phytoplankton samples were collected, preserved, and concentrated in settling chambers to determine taxonomic composition and algal biovolume. Unpreserved phytoplankton samples were also collected and used to generate a species list for each lake. The data were examined using correlation analysis and hierarchical clustering to evaluate relationships between water quality parameters and phytoplankton assemblages. The phytoplankton communities were quite diverse, and many species were collected that are described as uncommon in the taxonomic literature. Correlation analysis between water quality variables produced results consistent with the literature. Total phosphorus and total nitrogen both exhibited significant correlations with chlorophyll-a. In addition, significant correlations also occurred between alkalinity, pH, and conductivity. There were also many significant correlations between algal population parameters. In general, when Cyanobacteria increased in percentage, other species, most notably Chlorophyta, decreased, and as Cyanobacteria became dominant, other algal populations became less diverse. Lakes with similar water quality parameters clustered together. Lakes also clustered based on algal population structure, though cluster membership was different for water quality parameters versus algal assemblages. Lakes with high algal density clustered together. These lakes were almost always dominated by Cyanobacteria. My results indicated that as algal density increased, the populations became more dominated by Cyanobacteria and diversity decreased.





Western Washington University

OCLC Number


Subject – LCSH

Freshwater phytoplankton--Effect of water quality on--Washington (State); Freshwater phytoplankton--Ecology--Washington (State); Algal communities--Effect of water quality on--Washington (State)

Geographic Coverage

Washington (State)




masters theses




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