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Please use this identifier to cite or link to this item: http://hdl.handle.net/10204/6247

Title: Ecosystem change and the Olifants River crocodile mass mortality events
Authors: Woodborne, S
Huchzermeyer, D
Govender, D
Pienaar, D
Hall, G
Myburgh, J
Deacon, A
Venter, J
Lubcke, N
Keywords: Aquatic biodiversity
Clarias gariepinus
Crocodilus niloticus
Hydrocynus vittatus
Lotic foodwebs
Stable isotopes
Nile crocodile
Issue Date: Oct-2012
Publisher: Ecological Society of America (ESA)
Citation: Huchzermeyer, S, Govender, D, Pienaar, D, Hall, G, Myburgh, J, Deacon, A, Venter, J and Lubcke, N. 2012. Ecosystem change and the Olifants River crocodile mass mortality events. Ecosphere, vol. 3(10),87. http://dx.doi.org/10.1890/ES12-00170.1
Series/Report no.: Workflow;9742
Abstract: Nile crocodile (Crocodilus niloticus) mass mortality events in the Olifants River between the Letaba River confluence in South Africa and Lake Massingir in Mozambique have been attributed to pansteatitis: a disease that affects fat depots of the animals. The disease is also found in sharptooth catfish (Clarias gariepinus) in the same area, and the cause of the disease is attributed to pollution. Although the Olifants River Valley is polluted, the impact of interventions such as dam construction on biodiversity receives little attention. We show that the onset of the pansteatitis epidemic in crocodiles and sharp tooth catfish at the Olifants/Letaba confluence coincided with back-flooding of Lake Massingir that changed the Olifants River from a rock and sand substrate river to a clay substrate lake. Isotopic analysis shows that sharptooth catfish shifted from a predominantly vegetarian to a piscivorous diet that is highly correlated with pansteatitis prevalence, and crocodiles and tiger fish (Hydrocynus vittatus) show coincident trophic level increases. The evidence suggests that the ecosystem change altered the structure of the lotic foodweb and that an exotic or extralimital fish has invaded the confluence and is the vector of the pansteatitis epidemic. The invasive fish species is yet to be identified. The pansteatitis epidemic is an unintended ecological consequence of damming this river.
Description: Copyright: 2012 Woodborne et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits restricted use, distribution, and reproduction in any medium, provided the original author and sources are credited.
URI: http://www.esajournals.org/doi/pdf/10.1890/ES12-00170.1
ISSN: 2212-0416
Appears in Collections:Water resources and human health
Ecosystems processes & dynamics
Systems biology
General science, engineering & technology

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