Enigmatic amphibian declines were first reported in southern and southeastern Brazil in the late 1980s and included several species of stream-dwelling anurans (families Hylodidae and Cycloramphidae). At that time, we were unaware of the amphibian-killing fungus Batrachochytrium dendrobatidis (Bd); therefore, pollution, habitat loss, fragmentation and unusual climatic events were hypothesized as primary causes of these declines. We now know that multiple lineages of Bd have infected amphibians of the Brazilian Atlantic forest for over a century, yet declines have not been associated specifically with Bd outbreaks. Because stream-dwelling anurans occupy an environmental hotspot ideal for disease transmission, we investigated temporal variation in population and infection dynamics of three stream-adapted species (Hylodes asper, H. phyllodes, and Cycloramphus boraceiensis) on the northern coast of São Paulo state, Brazil. We surveyed standardized transects along streams for four years, and show that fluctuations in the number of frogs correlate with specific climatic variables that also increase the likelihood of Bd infections. In addition, we found that Bd infection probability in C. boraceiensis, a nocturnal species, was significantly higher than in Hylodes spp., which are diurnal, suggesting that the nocturnal activity may either facilitate Bd zoospore transmission or increase susceptibility of hosts. Our findings indicate that, despite long-term persistence of Bd in Brazil, some hosts persist with seasonally variable infections, and thus future persistence in the face of climate change will depend on the relative effect of those changes on frog recruitment and pathogen proliferation.
Instituto de Biologia, Universidade Federal do Rio de Janeiro, Ilha do Fundão, Rio de Janeiro, Brazil;Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, New York, United States of America;Departamento de Ecologia, Instituto de Biociências, Universidade de São Paulo, São Paulo, Brazil;Departamento de Ecologia, Instituto de Biociências, Universidade de São Paulo, São Paulo, Brazil;Laboratório de História Natural de Anfíbios Brasileiros (LaHNAB), Departamento de Biologia Animal, Instituto de Biologia, Universidade Estadual de Campinas, Campinas, São Paulo, Brazil;Laboratório de Antígenos Bacterianos, Departamento de Genética, Evolução e Bioagentes, Instituto de Biologia, Universidade Estadual de Campinas, Campinas, São Paulo, Brazil;Instituto de Biologia, Universidade Federal do Rio de Janeiro, Ilha do Fundão, Rio de Janeiro, Brazil;Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, New York, United States of America;Laboratório de História Natural de Anfíbios Brasileiros (LaHNAB), Departamento de Biologia Animal, Instituto de Biologia, Universidade Estadual de Campinas, Campinas, São Paulo, Brazil;Departamento de Ecologia, Instituto de Biociências, Universidade de São Paulo, São Paulo, Brazil
Recommended Citation:
Joice Ruggeri,Ana V. Longo,Marília P. Gaiarsa,et al. Seasonal Variation in Population Abundance and Chytrid Infection in Stream-Dwelling Frogs of the Brazilian Atlantic Forest[J]. PLOS ONE,2015-01-01,10(7)