ESR 21:115-128 (2013)  -  DOI: https://doi.org/10.3354/esr00514

Morbidity and mortality of the Critically Endangered Lake Oku clawed frog Xenopus longipes 

T. M. Doherty-Bone1,8,*, R. K. Ndifon2, O. N. Nyingchia2, F. E. Landrie3, F. T. Yonghabi3, A. L. J. Duffus4,9, S. Price4, M. Perkins4, J. Bielby4, N. B. Kome5, M. LeBreton6, L. N. Gonwouo7, A. A. Cunningham

1Department of Zoology, Natural History Museum, London SW7 5BD, UK
2Oku Fon’s Palace, Elak-Oku, North West Region, Cameroon
3Belo Rural Development Project, Belo, North West Region, Cameroon
4Institute of Zoology, Regents Park, London NW1 4RY, UK
5Institute of Agricultural Research for Development, Ekona, South West Province, Cameroon
6Global Viral Forecasting Initiative-Cameroon, CRESAR, Yaoundé, Cameroon
7Cameroon Herpetology-Conservation Biology Foundation (CAMHERP-CBF), PO Box 8218, Yaoundé, Cameroon
8Present address: School of Geography and School of Biology, University of Leeds, Leeds LS2 9JT, UK
9Present address: Division of Mathematics and Natural Sciences, Gordon State College, Barnesville, Georgia 30204, USA

ABSTRACT: Between 2006 and 2010, recurring morbidity and mortality of the endemic Lake Oku clawed frog Xenopus longipes was observed at its only known locality, Lake Oku, Cameroon. During repeated visits in 2006, 2008, 2009 and 2010, we found large numbers of dead frogs around the lake shore, as well as a higher than expected prevalence of diseased frogs. No significant relationships between disease occurrence and environmental parameters were found, with the exception of a significant but unexplained association between phosphate concentration and disease incidence. Tissue samples from X. longipes collected during 3 field seasons were negative for the amphibian chytrid fungus Batrachochytrium dendrobatidis (Bd) using a Bd-specific real-time PCR test, although other species of sympatric amphibians were positive for this pathogen. Only 1 of 48 tissue samples from diseased frogs was positive for ranavirus infection using a ranavirus-specific PCR, suggesting that this pathogen is not necessarily the cause of this disease. No evidence of pathogens was found in tissues examined histologically from 10 X. longipes which had been collected and fixed when freshly dead. The cause(s) of the morbidities and mortalities remain(s) unknown, as does their consequence to the population of this Critically Endangered species. Identifying the causative factor(s) of the X. longipes mortality and its impact on the population is crucial for planning conservation actions.


KEY WORDS: Amphibian declines · Disease · Limnology · Batrachochytrium dendrobatidis · Ranavirus · Cameroon


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Cite this article as: Doherty-Bone TM, Ndifon RK, Nyingchia ON, Landrie FE and others (2013) Morbidity and mortality of the Critically Endangered Lake Oku clawed frog Xenopus longipes . Endang Species Res 21:115-128. https://doi.org/10.3354/esr00514

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