AMPHIBIAN CHYTRID FUNGUS (BATRACHOCHYTRIUM DENDROBATIDIS) IN COASTAL AND MONTANE CALIFORNIA, USA ANURANS

We found amphibian chytrid fungus (Bd = Batrachochytrium dendrobatidis) to be widespread within a coastal watershed at Point Reyes National Seashore, California and within two high elevation watersheds at Yosemite National Park, California. Bd was associated with all six species that we sampled (Bufo boreas, B. canorus, Pseudacris regilla, Rana draytonii, R. sierrae, and Lithobates catesbeianus). For those species sampled at 10 or more sites within a watershed, the percentage of Bd-positive sites varied from a low of 20.7% for P. regilla at one Yosemite watershed to a high of 79.6% for P. regilla at the Olema watershed at Point Reyes. At Olema, the percent of Bd-positive water bodies declined each year of our study (2005-2007). Because P. regilla was the only species found in all watersheds, we used that species to evaluate habitat variables related to the sites where P. regilla was Bd-positive. At Olema, significant variables were year, length of shoreline (perimeter), percentage cover of rooted vegetation, and water depth. At the two Yosemite watersheds, water depth, water temperature, and silt/mud were the most important covariates, though the importance of these three factors differed between the two watersheds. The presence of Bd in species that are not declining suggests that some of the amphibians in our study were innately resistant to Bd, or had developed resistance after Bd became established.