CANCELLED - Does eutrophication contribute to disease emergence? A case study of an emerging amphibian pathogen

Background/Question/Methods

An emerging amphibian pathogen, the chytrid fungus Batrachochytrium dendrobatidis (Bd), is a known agent of global amphibian declines and extinctions. Despite the large body of work involving Bd, few studies exist examining why Bd is located sporadically across habitats.  Identification of factors contributing toward presence of this important pathogen may aid in the understanding of the recent increase in the emergence of pathogens worldwide. We addressed the relationship between aquatic nutrients and presence of Bd, focusing on three factors that are known to affect aquatic biodiversity and parasite emergence: aquatic total nitrogen, total phosphorus, and chlorophyll levels affect the presence and prevalence.  We focused on identifying Bd infections in individuals of two widespread genera, Hyla and Rana. Our data come from a large-scale pond survey of over 50 ponds in natural areas throughout eastern Missouri, from which we collected water samples and tissue samples from tadpoles to determine the presence or absence of Bd through histology and real time PCR assays.  Our goal was to identify correlations among aquatic nutrients and productivity and presence of prevalence of Bd among and within ponds.

Results/Conclusions

Across 10 ponds, our preliminary results show a trend indicating a negative correlation between Phosphorus concentrations and the percent of Hyla tadpoles infected with Bd (p= 0.129). We are currently investigating the prevalence of Bd in the genus Rana in 30 additional ponds. Anthropogenic eutrophication due to pollution and increased use of fertilizers is now a common form of global change, and a better understanding of how nutrient loading affects aquatic systems and declining amphibians is essential to the conservation of these highly endangered systems.