The Lethal Fungus Batrachochytrium dendrobatidis Is Present in Lowland Tropical Forests of Far Eastern Panamá

Abstract

The fungal disease chytridiomycosis, caused by Batrachochytrium dendrobatidis (Bd), is one of the main causes of amphibian population declines and extinctions all over the world. In the Neotropics, this fungal disease has caused catastrophic declines in the highlands as it has spread throughout Central America down to Panamá. In this study, we determined the prevalence and intensity of Bd infection in three species of frogs in one highland and four lowland tropical forests, including two lowland regions in eastern Panamá in which the pathogen had not been detected previously. Bd was present in all the sites sampled with a prevalence ranging from 15–34%, similar to other Neotropical lowland sites. The intensity of Bd infection on individual frogs was low, ranging from average values of 0.11–24 zoospore equivalents per site. Our work indicates that Bd is present in anuran communities in lowland Panamá, including the Darién province, and that the intensity of the infection may vary among species from different habitats and with different life histories. The population-level consequences of Bd infection in amphibian communities from the lowlands remain to be determined. Detailed studies of amphibian species from the lowlands will be essential to determine the reason why these species are persisting despite the presence of the pathogen.

Skin bacterial diversity of Panamanian frogs is associated with host susceptibility and presence of Batrachochytrium dendrobatidis

“…A portion of the DNA extracts was used for the detection of Bd using Taqman real-time PCR assay according to Rebollar et al (2014). Bd prevalence and infection intensity of C. fitzingeri from Soberania, Gamboa and Mamoni were previously reported (Rebollar et al, 2014), and the same methods were used in this study for all frog samples at Sapo.…”

“…In addition, the amphibian community observed in this site included a high abundance of susceptible species that do not occur anymore in Bd-infected sites (Hughey MC and Ibáñez R, unpublished data). Frogs were captured and skin swabs were collected according to previously published procedures (Rebollar et al, 2014). In addition to frog swabs, we collected 'perch swabs' from the exact place where each frog was found immediately after capturing an individual by swabbing the perch site for 20 s. We consider that perch samples represent an accurate collection of the microhabitat that each species occupies.…”

“…To address our third hypothesis, C. fitzingeri were collected and swabbed from three additional lowland forests sites (N = 37) that are considered endemic for Bd (Soberania, Gamboa and Mamoni) in Colon and Panama provinces, Panama (Table 2; sample collection described in Rebollar et al, 2014). These sites were closer together in comparison to the Bd-naive site, which is located in the Darien province (Figure 3e).…”

“…Second, we compare bacterial communities of Bd susceptible and nonsusceptible species, since susceptible species still occurred in high abundances at the study site. To address the third hypothesis, we compared the skin bacterial communities of one widely distributed species, C. fitzingeri at the Bd-naive site in the Darien province and at three Bd-endemic sites in the Panama and Colon provinces (Woodhams et al, 2008;Rebollar et al, 2014). As part of evaluating the third hypothesis, we determined whether site-level differences in the skin microbiota, if present, were associated with differences in environmental communities.…”

Direct and Indirect Horizontal Transmission of the Antifungal Probiotic Bacterium Janthinobacterium lividum on Green Frog (Lithobates clamitans) Tadpoles

“…B. dendrobatidis has caused extinctions of amphibian species in the tropics, including tropical Australia (10) and the Neotropics in Central America (11,12). However, some species are considered resistant or tolerant since they are persisting in the wild despite the presence of the pathogen (13,14). In order to reduce the risk of population declines or extinctions in susceptible amphibians, effective mitigation protocols must be developed.…”