Contrasting Seasonal Prevalence of Batrachochytrium dendrobatidis on Anurans in Fragmented Urban Forests

Understanding infection dynamics of emerging pathogens, such as Batrachochytrium dendrobatidis (Bd) is crucial for wildlife conservation, especially in highly disturbed urban ecosystems that support diverse host communities. While Bd typically thrives in cool, humid environments, recent studies have shown that it can exhibit plasticity to warmer conditions. Our study was conducted in fragmented urban forests of Guayaquil and Durán, Ecuador, a coastal region characterized by warm temperatures year-round and facing rapid habitat loss. We hypothesized that seasonal changes associated with temperature and precipitation, anuran species richness, host family, and habitat fragment size would influence Bd infection dynamics. We found that Bd prevalence was influenced by season and host taxonomy, with the highest infection rates during the dry season and in the family Leptodactylidae. Specifically, Bd prevalence across all sites was 10.7%; with an overall prevalence of 2.5% during part of the rainy season (February to April), and 26.0% when temperatures and precipitation were lower (May to July). We also found lower amphibian richness in smaller forest fragments and during the dry season, which appeared to amplify pathogen prevalence. Our research elucidates Bd dynamics in seasonally dry tropical coastal forests and highlights the importance of considering variables associated with dry and rainy seasons (i.e., temperature and precipitation) in disease ecology and conservation planning. Understanding these dynamics is essential for safeguarding amphibian populations in the face of ongoing urbanization and climate change.