State-wide survey of amphibian pathogens in green frog (lithobates clamitans melanota) reveals high chytrid infection intensities in constructed wetlands

We screened populations of larval Green Frogs (Lithobates clamitans melanota) for Ranavirus spp. and Batrachochytrium dendrobatidis (Bd) in naturally occurring reference wetlands (n = 12) and wetlands constructed for loss of habitat elsewhere (n = 12) throughout Pennsylvania, USA. We detected the ranavirus, Frog Virus 3, in one natural and one constructed wetland, and Bd occurred in 11 natural wetlands and 10 constructed wetlands. Infection intensities of Bd (zoospores per infected individual) were significantly higher in constructed (median = 771, mean ± SE = 1514 ± 450) than reference wetlands (median = 242, mean = 487 ± 216), and constructed wetlands contained four of the six highest Bd prevalence values. Our results suggest that infection intensity decreased with increasing forest cover, but only among wetlands with few anthropogenic disturbances and that best management practices for forested riparian zones may differ along gradients of human disturbance. If constructed wetlands are to replace and mitigate the loss of the ecological functions of natural wetlands, wetland-dependent wildlife need to withstand stressors like disease. To achieve this, resource managers should understand the role constructed wetlands play in the persistence and spread of emergent infectious disease.