West Africa - a safe haven for frogs? A sub-continental assessment of the Chytrid Fungus (Batrachochytrium dendrobatidis)

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Date
2013Author
Penner, Johannes
Weldon, Ché
Adum, Gilbert B.
McElroy, Matthew T.
Doherty-Bone, Thomas
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A putative driver of global amphibian decline is the panzootic chytrid fungus Batrachochytrium dendrobatidis (Bd). While Bd
has been documented across continental Africa, its distribution in West Africa remains ambiguous. We tested 793 West
African amphibians (one caecilian and 61 anuran species) for the presence of Bd. The samples originated from seven West
African countries - Be´nin, Burkina Faso, Coˆ te d’Ivoire, Ghana, Guinea, Liberia, Sierra Leone - and were collected from a variety
of habitats, ranging from lowland rainforests to montane forests, montane grasslands to humid and dry lowland savannahs.
The species investigated comprised various life-history strategies, but we focused particularly on aquatic and riparian
species. We used diagnostic PCR to screen 656 specimen swabs and histology to analyse 137 specimen toe tips. All samples
tested negative for Bd, including a widespread habitat generalist Hoplobatrachus occipitalis which is intensively traded on
the West African food market and thus could be a potential dispersal agent for Bd. Continental fine-grained (30 arc seconds)
environmental niche models suggest that Bd should have a broad distribution across West Africa that includes most of the
regions and habitats that we surveyed. The surprising apparent absence of Bd in West Africa indicates that the Dahomey
Gap may have acted as a natural barrier. Herein we highlight the importance of this Bd-free region of the African continent -
especially for the long-term conservation of several threatened species depending on fast flowing forest streams (Conraua
alleni (‘‘Vulnerable’’) and Petropedetes natator (‘‘Near Threatened’’)) as well as the ‘‘Critically Endangered’’ viviparous toad
endemic to the montane grasslands of Mount Nimba (Nimbaphrynoides occidentalis).