Graduation Year


Document Type

Master's Thesis


Master of Science


Biological Science

Program Director

Meredith Protas, PhD

First Reader

Wolfgang Schweigkofler, PhD

Second Reader

Vania Coelho, PhD


Oomycetes, also known as water molds, belong to the kingdom Stramenopila and are a well-known group of plant pathogens and saprophytes. Important species include Phytophthora ramorum (causal agent of sudden oak death), Pythium aphanidermatum (root rot), and Phytophthora infestans (late potato blight), all major threats to the environment, agriculture, and the economy. Although many oomycete species have been found in various water sources, little is known about the correlation between the distribution and frequency of oomycetes in aquatic environments and physical chemical water parameters. The objective of this study was to detect and identify aquatic oomycetes from Marin County using repeated seasonal sampling and DNA sequencing and to analyze relevant physical chemical water characteristics such as temperature, pH, conductivity, turbidity, total suspended solids, biochemical oxygen demand, and bacteriological contamination. Throughout June of 2019 to April of 2020 a total of 180 different samples were collected from nine different sampling locations throughout Marin Country. From those 180, 67 isolates (37%) grew into colonies, which were identified as 15 different species, including one Unclassified Ovatisporangium. Water quality characteristics varied across seasons and locations, and the correlation to microbial diversity has yet to be determined.