Effects of pH and Temperature Variability on Fungal Pathogen Development and Population Survival in Daphnia

For this project, based in the lab of Dr. John Drake, Trianna Humphrey worked with Tad Dallas to study the effect of changing environmental conditions on a host-parasite relationship.

Trianna Humphrey, Tougaloo College

Tad Dallas, Odum School of Ecology, University of Georgia

 Extreme environmental conditions can have an influence on host-parasite relationships and capable of altering interactions. Extreme conditions on Daphnia dentifera, also known as water fleas, and it’s fungal pathogen (Metschnikowia bicuspidata), can alter disease dynamics and population dynamics. This study was designed to answer the question, “Does the influence of temperature variability have an effect on the host-parasite relationships within Daphnia.”  Also we wanted to answer the question ”Does a change in pH have an effect on the host-parasite relationships or an effect on the population?” We show that we exposed half the population to the pathogen. A temperature of 20C was used as a control and 12C and 28C were the two extreme temperatures, with time variations of either 0,1,2, or 4 hours. This study is ongoing and data are still being collected. To alter the pH, we added a HCL solution to the populations and exposed half the populations to the pathogen to answer the question ”Does pH have an effect on infection and spores within Daphnia?”  After examining the data, we didn’t find any useful data to answer our big question.

Download (PDF, 1.1MB)