Original Research

Eco-epidemiological and pathological features of wildlife mortality events related to cyanobacterial bio-intoxication in the Kruger National Park, South Africa

Roy Bengis, Danny Govender, Emily Lane, Jan Myburgh, Paul Oberholster, Peter Buss, Leon Prozesky, Dewald Keet
Journal of the South African Veterinary Association | Vol 87, No 1 | a1391 | DOI: https://doi.org/10.4102/jsava.v87i1.1391 | © 2016 Roy Bengis, Danny Govender, Emily Lane, Jan Myburgh, Paul Oberholster, Peter Buss, Leon Prozesky, Dewald Keet | This work is licensed under CC Attribution 4.0
Submitted: 08 February 2016 | Published: 31 October 2016

About the author(s)

Roy Bengis, Private Wildlife Practice, Port Alfred, South Africa
Danny Govender, Scientific Services, South African National Parks, Skukuza; Department of Paraclinical Sciences, University of Pretoria, Onderstepoort, South Africa
Emily Lane, Department of Research and Scientific Services, National Zoological Gardens of South Africa, South Africa
Jan Myburgh, Department of Paraclinical Sciences, University of Pretoria, Onderstepoort, South Africa
Paul Oberholster, CSIR Natural Resources and the Environment, Stellenbosch, South Africa
Peter Buss, Veterinary Wildlife Services, South African National Parks, Skukuza, South Africa
Leon Prozesky, Department of Paraclinical Sciences, University of Pretoria, Onderstepoort, South Africa
Dewald Keet, Private Wildlife Practice, Phalaborwa, South Africa


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Abstract

Over the past decade, several clustered, multispecies, wildlife mortality events occurred in the vicinity of two man-made earthen dams in the southern and south central regions of the Kruger National Park, South Africa. On field investigation, heavy cyanobacterial blooms were visible in these impoundments and analysis of water samples showed the dominance of Microcystis spp. (probably Microcystis aeruginosa). Macroscopic lesions seen at necropsy and histopathological lesions were compatible with a diagnosis of cyanobacterial intoxication. Laboratory toxicity tests and assays also confirmed the presence of significant levels of microcystins in water from the two dams. These outbreaks occurred during the dry autumn and early winter seasons when water levels in these dams were dropping, and a common feature was that all the affected dams were supporting a large number of hippopotamuses (Hippopotamus amphibius). It is hypothesised that hippopotamus’ urine and faeces, together with agitation of the sediments, significantly contributed to internal loading of phosphates and nitrogen – leading to eutrophication of the water in these impoundments and subsequent cyanobacterial blooms. A major cause for concern was that a number of white rhinoceros (Ceratotherium simum) were amongst the victims of these bio-intoxication events. This publication discusses the eco-epidemiology and pathology of these clustered mortalities, as well as the management options considered and eventually used to address the problem.


Keywords

cyanobacterial bloom; eutrophication; hippopotamus; Microcystis spp; microcystins; Kruger National Park; eco-epidemiology; pathology; wildlife mortality

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