Factors affecting local, regional, and global scale cyanobacterial dominance and secondary metabolite occurrence

Abstract

Cyanobacteria are photosynthetic bacteria that serve as a primary producer in aquatic ecosystems. Cyanobacterial harmful algal blooms (CyanoHABs) are a major cause of water quality degradation in rivers, lakes, and estuaries worldwide because they disrupt food-webs and cause substantial changes in pH and dissolved oxygen. Additionally, many cyanobacterial species are capable of producing a suite of potent toxins and other secondary metabolites that cause taste and odor problems in drinking water supplies. The primary goal of my dissertation is to better understand the factors controlling CyanoHABs and their associated secondary metabolites at local, regional, and global scales. I examined the factors that control local-scale CyanoHABs and the cyanobacterial metabolites microcystin and geosmin by comparing 12 linear and non-linear regression modeling techniques using a continuous 14 year dataset collected from Cheney Reservoir, Kansas. In Chapter 2, I explored the factors that control regional-scale cyanobacterial abundance, microcystin, geosmin, and 2-methylisoborneol concentrations in 4 Midwestern US reservoirs. Then, I used a meta-analysis to evaluate the relation of persistent organic pollutants, which include herbicides, pesticides, pharmaceutical, personal care products, and industrial chemicals, to CyanoHABs on a global scale in Chapter 3. Overall, the three chapters indicate that cyanobacterial blooms and their associated metabolites are driven by numerous factors at different scales.