Infecção pelo fungo batrachochytrium dendrobatidis (chytridiomycota) na anurofauna da reserva biológica de Pedra Talhada, nordeste do Brasil

Abstract

Amphibians are the most threatened group of vertebrates. The fungus Batrachochytrium dendrobatidis (Bd) is known for causing population declines and extinctions in amphibians around the world. In Brazil, the country with the highest global diversity of amphibians, the pathogen is widely distributed in the Atlantic Forest, and the dynamics of infection are influenced by abiotic and biotic factors. However, few studies have been conducted in the Atlantic Forest in the northeast region, and it is not yet known whether this pathogen is present in the Pedra Talhada Biological Reserve (ReBio-PT), a conservation unit located between the states of Alagoas and Pernambuco. The objectives of this study were: 1) to investigate the presence of the fungus Bd in the anurans of ReBio-PT; 2) if present, to determine the prevalence and intensity of the infection by identifying the species of infected anurans and investigating whether biotic and abiotic factors are influencing the dynamics of the infection. A total of 12 collection stations (CS) were visited and up to 100 adult anuran individuals, regardless of their species, were analyzed by CS. For Bd fungus detection, individuals were collected manually and 25 smears using sterile swabs were performed following a standardized methodology. Each individual was released at the same location after swab collection. Genomic DNA was extracted from each swab sample and Bd quantification was performed using a Quantitative Real-Time Polymerase Chain Reaction. A total of 998 individuals were evaluated for Bd infection. The anurans showed a low prevalence of infection, with 30 infected individuals (3%). The intensity of infection ranged from 1 to 2 thousand genomic equivalents (e.g.) of zoospores. The data corroborated studies that suggest a positive association between infection dynamics and latitude, vegetation density and species richness. Elevation did not influence infection dynamics. The species Pristimantis ramagii, direct development, showed the highest prevalence, while species that indirect development showed the highest infection intensity. The phytophysiognomic characteristics of semideciduous seasonal forests may contribute to the formation of microclimates that are more favorable for the development of Bd. ReBio-PT showed a prevalence similar of other locations in the northeast, but the infection intensity was more similar with the Atlantic Forest locations in the southeast and south. Monitoring the anurans in this conservation unit is recommended to determine whether Bd infection will cause population declines.