Dissertation Research: Effects of propagule pressure and invasion resistance on establishment success of the toxic golden alga Prymnesium parvum

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Certain species of algae can have substantial socio-economic costs because they produce toxins that are harmful to other species in their environments, as well as to humans. Recently, a species of golden alga has exhibited a significant increase in its frequency and severity of toxic blooms in lakes and reservoirs nationally and globally. The spread of this species has been surprisingly rapid through US waterways during the last decade. To date, sixteen states have confirmed massive fish kills attributable to golden algae. This project will examine two hypothesized mechanisms for how invasive algal species become established in new environments. The first hypothesis is that enrichment of water with nutrients creates less diverse microbial communities, which are then less resistant to invasion. The second hypothesis is that invasion success is simply a function of the number of invaders that disperse to the new habitat. This research will conduct experiments in outdoor tanks at the University of Oklahoma Biological Station to test the ability of a lake community to resist invasion by golden algae. The experimental treatments will consist of different rates of introduction of golden algae and different levels of microbial diversity in the community, created through nutrient enrichment and quantified using DNA sequencing.This study represents a test of the applicability of general ecological theory to understanding freshwater microbial diversity, but also provides insight into what controls freshwater harmful algal invasions. As such, the results from this project are of broad relevance to the management of freshwater ecosystems. Results will be disseminated through scientific presentations and journal publications, and also through outreach to local communities and K-12 students and teachers that visit the university biological station. This project supports the dissertation research of a graduate student.