Discipline: Ecology Environmental and Earth Sciences
Akira N. Harris - Virginia State University
Batrachochytrium dendrobatidis (Bd) is an aquatically spread chytrid fungus that interferes with cutaneous respiration in amphibians often with lethal results. It has been implicated as a factor in the decline and extinction of more than 200 amphibian species worldwide. South America has been particularly impacted by its arrival, with Suriname being one of only three countries on the continent where Bd hasn’t been detected. Suriname is home to more than 100 species of amphibians, most of which are anurans (frogs and toads) and prior to this study testing for Bd in the country was sparse. However, the fungus had been found along the French Guianese side of the Marowijne River (a border separating Suriname from French Guiana) as well as in neighboring Brazil. Previous studies have shown the occurrence of the fungus to be associated with high human population density, the presence of moisture, and high amphibian biodiversity. We hypothesized that anurans in Brownsberg Nature Park would test positive for Bd since this area meets the aforementioned criteria, while the isolated populations of Dendrobates tinctorius azureaus would test negative for the fungus’ presence.
Eighty-five anurans representing 21 species were screened from seven locations in Suriname. Frogs were caught using sterile gloves and cutaneously swabbed. Samples were then preserved in a 70% ethanol solution and subsequently tested for the presence of Bd ribosomal RNA components using PCR. Results showed that Bd infection was not present in any of the specimens. This suggests that the fungus is absent from the regions of Suriname sampled. While the results do not support our hypothesis, they are consistent with previous conclusions from testing done in Brownsberg Nature Park in 2004. Further testing, particularly in areas near the Marowijne River, is necessary to ensure the accuracy of this outcome. However, the apparent absence of Bd from Suriname provides the opportunity to closely monitor and characterize anuran populations and high-risk areas prior to its arrival. It also provides time for proactive measures to be taken to protect particularly vulnerable species and populations in the country. Continuation of this research will deliver a better understanding of the movement patterns, environmental preferences, and likely vectors of Batrachochytrium dendrobatidis while offering an opportunity to curtail its further spread.
References: Olson, D.H., Aanenson, D.M., Ronnenberg, K.L., Powell, C.I., Walker, J., Bielby, T.W.J. Garner, G. Weaver, The Bd Mapping Group, and M.C. Fisher. 2013. Mapping the Global Emergence of Batrachochytrium dendrobatidis, the Amphibian Chytrid Fungus. PLoS ONE 8(2): e56802.
Rohr, J.R., Halstead, N.T. and Raffel, T.R. 2011. Modelling the future distribution of the amphibian chytrid fungus: the influence of climate and human-associated factors. Journal of Applied Ecology. 48:174-176.
Wake, D.B. and Vredenburg, V.T. 2008. Are we in the midst of the sixth mass extinction? A view from the world of amphibians. PNAS 105(1): 11466-11473.
Funder Acknowledgement(s): I thank D. Davidson, C.A. d’Orgeix, C. d’Orgeix, S. Greiner, D. Hardy, A. Velez, A. White, and S. Witiak for help in the field. I also thank R. Jairam from Anton de Kom Universiteit van Suriname for help in the field and the lending of his expertise. P. Ouboter from Anton de Kom Universiteit van Suriname lent logistical support and offered comments on our research. Also, I thank Dr. B. Sayre for his help. Funding was provided by an NSF/ HBCU-UP grant to C. d’Orgeix.
Faculty Advisor: Christian d'Orgeix,