This project is part supported by the Ecology of Infectious Diseases program. It will investigate the transmission of the human pathogen S. marcescens, which causes white pox disease (WPD), to the marine invertebrate Elkhorn coral. This coral was once the most common coral in the Caribbean and is now designated as a Threatened Species under the US Endangered Species Act. The goal of the study is to develop models to describe the population dynamics of Elkhorn coral, to predict transmission and future impacts of WPD (or acroporid serratiosis) and to help devise control strategies by understanding the factors that drive the emergence and maintenance of this disease. The modeling effort to capture the dynamics of a marine disease system is another strength of the research. Factors such as water quality, climate variability and patterns of human population density will be considered. Sampling will be performed biannually in summer and winter (or quarterly if WPD outbreaks occur) in Florida Keys National Marine Sanctuary and Dry Tortugas National Park. The science team will build upon previous work and broaden the understanding of a reverse zoonosis involving the transmission of a human pathogen to a threatened species of Caribbean coral. This is the first time a human disease has been shown to cause population declines of a marine invertebrate. The results will help understanding the pathogen and dynamics of this disease and the transmission and evolution of marine infectious diseases.