Graduate Program

Biological Sciences

Degree Name

Master of Science (MS)

Semester of Degree Completion

Fall 2023

Thesis Director

Barbara S. Carlsward

Thesis Committee Member

Scott J. Meiners

Thesis Committee Member

Yordan S. Yordanov

Abstract

Diatoms have been used as biological indicators for assessing the environmental health of waterways for over a century. Their low motility and responsiveness to environmental changes makes them ideal for this purpose. North Dakota oil extraction has undergone a massive transformation as hydraulic fracturing across the Bakken Formation and the Williston Basin has increased over the last 20 years. Hydraulic fracturing increased the potential for environmental pollution of North Dakota’s waterways, especially in the form of highly saline hydraulic fracturing liquid. Many North Dakota streams are already saline and additional salinity could cause drastic changes in aquatic ecosystems. North Dakota waterways are also prone to nutrient pollution from agricultural runoff. This study focused on surveying some of North Dakota’s waterways to establish reference diatom community assemblages for these streams. Physiochemical data was extracted from the United States Geological Survey waterway assessments for most sites. From this data and diatom assemblage counts, an attempt was made at assessing stream health. Most sites had high counts of pollution tolerant/halophilic taxa with matching environmental conditions that were expected from most of the North Dakota lotic systems. Sites that did not have issues with salinity had low nitrogen/phosphorus conditions that favored taxa tolerant to these nutrient imbalances. Park River seemed to be the healthiest system with low eutrophication and high diversity. The diatom assemblages and physiochemical data may serve as a baseline for future assessments of North Dakota rivers.

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