DISSERTATION RESEARCH: Do interactions between ultraviolet radiation and dissolved organic carbon modulate disease in aquatic systems?

Environmental change alters ecosystems by changing the physical characteristics of a habitat, affecting which organisms can thrive in a given environment. In this graduate student project, research will address the impacts of darkening water in Midwestern lakes on the prevalence of disease in a common miniature crustacean. Lake darkening occurs due to increases in input of plant debris washing into lakes as a result of increased precipitation and storm severity. Lake nutrient levels and the penetration of various wavelengths of light into the water are both affected by the darkening process. The common miniature crustacean known as Daphnia can be parasitized by certain fungi and/or bacteria. This project will examine the mechanisms by which lake darkening can affect these parasitic interactions. It will provide insight into how altering environmental factors can influence disease in lake communities, and will also involve local students in research and fieldwork in south-central Indiana.

In order to quantify how lake darkening affects disease dynamics in lakes, for this Doctoral Dissertation Improvement grant, the graduate student will manipulate the darkness of lake enclosures through two treatments: shading and addition of dissolved organic matter. The student will then seed enclosures with local community members (Daphnia hosts, other plankton, and invertebrate predators) and parasite-infected hosts. Abiotic habitat variables (e.g. temperature, pH, oxygen levels), community structure, and disease levels will be measured throughout the course of the ten-week experiment and compared to control enclosures without shading or added dissolved organic matter. Since lake darkening is expected to affect all lake community members either directly or indirectly, it is important to observe and quantify effects of these environmental factors on hosts, disease agents, predators, producers, decomposers, and physical habitat structure. By measuring differences in communities in the different treatments, we will be able to tease apart the mechanisms by which lake darkening affects disease.