Macrophyte-mediated breakdown of pyraclostrobin: effects of species, biomass, and environmental conditions on daphnia magna survival​

<p dir="ltr">Fungicides are a rising pesticide in the US and the world, but research on their many groups and the effect that those fungicides can have on aquatic environments is still lacking in many areas, including aquatic plants. I wanted to test whether macrophytes could increase the survival of an aquatic macroinvertebrate, the water flea Daphnia magna by breaking down a lethal dose of the fungicide pyraclostrobin. In the first chapter, I tested this by dosing treatments of 3 different macrophyte species, then letting them sit for 2, 6, and 10 hours. I found a significant effect of time delay on survival of D. magna, where 10 hours had the highest survival. However, inside of the delay treatments, there was no significant difference between species or density. There was a significant interactive effect between species and density. In my second chapter, I explored other factors that could influence the ability of macrophytes to break down pyraclostrobin, namely shade. I set up a factorial experiment with 3 increasing levels of shade, and exposed Elodea canadensis to pyraclostrobin for 10 hours before adding Daphnia. I found that biomass and shade significantly affected D. magna survival. I also found an interactive effect between biomass and shade, with lower survival in the higher biomass*shade interactions. The findings of my studies not only suggest that macrophytes are able to break down pyraclostrobin over time, but that the degradation of pyraclostrobin can be influenced by many factors, both biotic and abiotic. These studies provide evidence that the acute toxicity of pesticides can be countered with expedited degradation under the right conditions. </p>