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What is the context of this research?

Blue green algae (BGA) blooms have caused significant economic losses and pose health risks. Understanding the causes of these blooms is an important avenue of research. The ability to fix nitrogen enables BGAs to outcompete other algae, particularly under N-limitation, which is becoming increasingly common as phosphorus from anthropogenic sources alleviates phosphorus (P)-limitation and exacerbates N-limitation. N fixation is the process by which certain organisms can convert atmospheric N 2 gas into more biologically available forms. Thus, eutrophication provides ideal conditions for BGAs, with its ability to fix N, to outcompete benign algae. Much has been done regarding the N:P supply conditions that cause BGA blooms, although no clear answers have emerged, despite decades of research.

What is the significance of this project?

The availability of several other nutrients, including iron (Fe) vary tremendously among lakes. Surprisingly little is known about the role of Fe in determining BGA blooms, particularly because the enzyme that facilitates N fixation, nitrogenase, contains a large quantity of iron (Fe). This project aims to explore the relationship between Fe levels and BGA presence, particularly how they interact in relation to differing amounts of N and phosphorus (P). Numerous studies have shown that N and P concentrations influence algae growth. However, by looking at Fe concentrations, particularly when N is in limited supply and N fixers have an advantage, this project will result in a better understanding of the factors influencing these harmful algal blooms.

What are the goals of the project?

Our goal is to perform an in situ experiment where N:P:Fe supply ratios will be manipulated. Experiments will be performed in Grand Lake, Lake Hudson, and Lake Eucha, Oklahoma. We will fill the bottles with lake water from each lake. These bottles will have either +N, +P, +Fe, +NP, +NFe, +NP +PFe, or +NPFe (plus one control bottle) added to each and then placed in the lake. We will then measure the amount of algal growth in general and BGA in particular, as well as the nutrient concentrations over four days. We predict a positive relationship between BGA abundance and Fe. Moreover, we predict that this relationship will be strongest under +PFe treatment