The impact of episodic events on cHAB growth and secondary metabolite production

PROJECT SUMMARY: PROJECT 1 Extreme weather events quickly alter lakes' chemical (increase nutrients) and physical (temperature, light penetration) characteristics, which can promote cyanobacterial bloom development. Collectively, we term these extreme weather events and their effects "episodic events." Our proposal aims to resolve how episodic events affect bloom growth/maintenance, production of cyanotoxins and taste and odor (T&O) compounds, and phycosphere processes. Our study will include both planktonic and benthic blooms, as it is recognized that benthic cyanobacterial blooms pose human health and welfare concerns due to cyanotoxin production and their high biomasses. Additionally, we will investigate how production of several classes of cyanotoxins is altered by episodic events. This is made possible by expanding the Center's Facility Core, which now can measure many congeners of microcystins, saxitoxins, anatoxins, and anabaenopeptins. We also will analyze T&O compounds since these compounds, while not toxic, negatively affect the perception of drinking water. Moreover, because pathogenic bacteria (Klebsiella and Aeromonas) have been found in Lake Erie blooms, we will address the questions of what relationships exist between cyanobacteria and associated pathogens, whether blooms serve as reservoirs for pathogens, and if episodic events favor them. We will accomplish our objectives using an experimental approach and lake surveys. We will focus on planktonic blooms in Years 1 and 2, and the benthos in Years 3 and 4. In all years, we will conduct factorial experiments in Stone Lab's new state-of-the-art mesocosm facility to tease apart temperature, light, and nutrients synergistic interactions. The planktonic or benthic algae in the experiments will be held in the mesocosms at ambient conditions to accumulate before introducing the variables of episodic events. We will collect samples for algal biomass, cyanotoxins, T&O, nutrients (N & P), and phycosphere processes before and after the episodic events. Also, we will conduct experiments to determine how container size affects phytoplankton's response to changing environmental conditions. Results from the experiments can be interpreted through the lens of field samples taken from routine monitoring programs and additional sample collection following episodic events. In Years 1 and 2, we will coordinate with Project 2 and leverage other funding to collect weekly samples from 22 sites in Lake Erie. In Years 3 and 4, we will collect weekly Microseira wollei samples for cyanotoxins, phycosphere processes, and ambient water quality data. Models from the cellular to the lake ecosystem level will be informed by experimental data measuring plankton dynamics in various abiotic conditions; their predictions will be tested against field observations. By connecting knowledge gained by our project and Project 3, predictions will be made and tested for of cyanotoxin exposure via inhalation to lakeshore communities (Project 4).