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

PLoS One. 2013;8(2):e56236. doi: 10.1371/journal.pone.0056236. Epub 2013 Feb 13.

Abstract

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 - Bénin, Burkina Faso, Côte 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).

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Africa, Western / epidemiology
  • Animals
  • Anura / microbiology*
  • Chytridiomycota / genetics*
  • Dermatomycoses / epidemiology*
  • Dermatomycoses / veterinary*
  • Ecosystem
  • Models, Biological
  • Polymerase Chain Reaction
  • Species Specificity

Grants and funding

Fieldwork in Benin, Burkina Faso and Côte d’Ivoire was funded by the German Ministry for Education and Research (BMBF) through the BIOTA-West project (01LC0617J). In Ghana, fieldwork for GBA, COB and WO was supported by Defra’s Darwin Initiative/ZSL’s Wildlife Wood Project and the Rufford Small Grants Foundation respectively. Analyses of samples in Berlin were conducted within a project financed by the German Science Foundation (DFG PL 213/6-1). The authors further thank the DFG (VE 183/4-1, RO 3064/1-2), the Rapid Assessment Program and Critical Ecosystem Partnership Fund of Conservation International, the World Wide Fund for Nature and BirdLife International for additional funding. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.