Date of Award

Spring 2023

Document Type

Open Access Dissertation


Chemistry and Biochemistry

First Advisor

John Ferry


Cyanobacteria are some of the oldest recorded organisms on earth and through the years have utilized a variety of adaptations to establish themselves in nearly all environments found on this planet. These autotrophic organisms are found in fresh and saltwater systems where they can sequester nutrients or produce their own and often take advantage of eutrophic systems to establish large populations or blooms. These organisms regularly produce secondary metabolites, however the concentrations of these metabolites during blooms become much more apparent and have greater, more detrimental impacts on the water quality of a system. These metabolites can directly affect water infrastructure by preventing the use of impacted waterbodies as drinking water sources or requiring substantial treatment before becoming suitable for consumption or recreation. Additionally, toxic secondary metabolites pose an even greater threat to the health and safety of humans and other organisms that live in or near a waterbody experiencing a bloom. The work discussed in this dissertation addresses the environmental fate and potential risk of metabolites derived from cyanobacterial mats dominated by the benthic cyanobacterium Microseira wollei.

The first class of toxic secondary metabolites observed in this system include the saxitoxin analogues unique to Microseira wollei termed the Lyngbya wollei toxins or LWTs 1-6. These toxins were qualified and quantified using established methods and the work here addressed the environmental fate and attenuation processes of these toxins in the water column. Degradation mechanisms and byproduct formation regarding the LWTs were determined and empirical models were developed to address theoretical attenuation of toxins in the field. These models also served as predictors for changes in the risks and hazards associated with toxin release in freshwater settings. Additional work was done to determine the interaction between toxins and sediments and the potential role the sediments have on attenuation processes.

The second class of metabolites analyzed here included volatile linear and branched aliphatic hydrocarbons or alkanes that are ubiquitous to cyanobacteria. While these chemicals associated with cyanobacteria were not previously considered toxic, literary evidence has linked various exposure routes of alkanes in humans to several immunological and allergic conditions including lupus and arthritis. Here, over 20 linear alkanes and several branched alkanes were qualified and quantified. Alkane distributions within aqueous and biomass samples collected at a bloom site were determined spatially and temporally. Evaporation rates for the alkanes were determined and used to estimate bioproduction rates. These rates were used to determine the potential risk alkane production by cyanobacterial mats has on human health and safety of impacted waters.


© 2023, Tryston Taylor Metz

Available for download on Thursday, May 15, 2025

Included in

Chemistry Commons