SLIDE 1
Pansteatitis in Clarias gariepinus in the Kruger National Park is not restricted to the Olifants Gorge Huchzermeyer KDA
Sterkspruit Veterinary Clinic University of Pretoria WRC Consultancy Project K8/948
SLIDE 2 Pansteatitis
- Inflammatory reaction that accompanies the
generalized necrosis of fat
- Described from many species of warm and
cold blooded animals including fish
- Generally regarded as a function of
polyunsaturated fat consumption and dietary vitamin E intake
- May be initiated by exogenous factors
SLIDE 3 Consumption of fish
- Most cases described in the literature
associated with exclusive consumption of fish or
- Diets known to be lacking in vitamin E
- Steatitis has been reported from wild fish
after suspected exposure to pro-oxidant pollutants
Photo Reuters
SLIDE 4 Process leading to pansteatitis
- Redox cycling of various compounds can result in damage to
polyunsaturated lipids causing release of lipid hydroperoxides
- Lipid hydroperoxides decompose to highly reactive lipid free
radicals
- Lipid free radicals promote further peroxidation of
polyunsaturated lipids and initiate damage to cell and nuclear membranes
- Vitamin E protects polyunsaturated lipids from damage
caused by lipid free radicals
SLIDE 5
Field sampling – fish health investigation
Olifants Letaba confluence Olifants Gorge Mozambique border Olifants River Mamba weir Letaba Engelhardt dam Sabiepoort Reenvoel dam
SLIDE 6
Dissecting fish in Skukuza
SLIDE 7
Gorge July 2010 & January 2011 Nile crocodile Olifants Gorge August 2009
SLIDE 8 Prevalence of macroscopically detectable steatitis lesions in C. gariepinus from the Olifants River gorge on various sampling occasions during 2009.
Date Sampling site % Fish with steatitis Total fish sampled June 2009 Olifants Letaba confluence 33 % 9 June 2009 Olifants Letaba confluence 75 % 4 July 2009 Olifants Letaba confluence 100 % 6 August 2009 Gorge Mozambique border 33 % 12 November 2009 Olifants Letaba confluence 29 % 21
SLIDE 9 Histological prevalence of steatitis in
Date Sampling site % Fish with steatitis Total fish sampled July 2010 Mamba weir 5 % 20 July 2010 Engelhardt Dam 15 % 20 July 2010 Olifants Letaba confluence 48 % 25 July 2010 Sabie poort 45 % 11
SLIDE 10
Prevalence of macroscopically detectable steatitis lesions in C. gariepinus sampled from the Olifants River gorge during 2011.
Date Sampling site % Fish with steatitis Total fish sampled
January 2011 Olifants Letaba confluence 55 % 22
SLIDE 11 Prevalence of macroscopically detectable steatitis lesions in negative and positive control populations of C. gariepinus
Date Sampling site % Fish with steatitis Total fish sampled November 2009 Reenvoel Dam 0 % 23 November 2009 Lunsklip Fisheries 66 % 21 January 2011 Reenvoel Dam 0 % 13
SLIDE 12 Steatitis prevalence in sampled
10 20 30 40 50 60 Mar-09 Jul-09 Oct-09 Jan-10 May-10 Aug-10 Nov-10 Feb-11 Olifants Gorge Mamba Weir Engelhardt Dam Sabiepoort Power (Olifants Gorge)
SLIDE 13 Olifants Gorge Letaba confluence
SLIDE 14
Olifants Gorge Mozambique border and Massingir Dam
SLIDE 15 Sabiepoort and Coromani Dam
SLIDE 16 Reenvoel Dam
- Rainfall catchment
- Phytoplankton bloom
SLIDE 17
benthic scavenger
Receding flood waters Olifants Letaba confluence January 2011
SLIDE 18
Stomach content of C. gariepinus during Olifants flood January 2011
SLIDE 19
Stomach content of C. gariepinus during Olifants flood January 2011
SLIDE 20
- C. gariepinus varying amounts of fat
- Mamba weir
- Olifants Letaba
confluence
SLIDE 21 Engelhardt Dam – C. gariepinus with severe chronic steatitis July 2010
- Mesenteric fat body
- Cross section of
mesenteric fat body
SLIDE 22
Engelhardt Dam – C. gariepinus with early recent steatitis July 2010
SLIDE 23 Steatitis in mesenteric fat of
- C. gariepinus from Olifants Gorge July
2010
- Mesenteric fat body
- Cross section of
mesenteric fat body
SLIDE 24 Pansteatitis in C. gariepinus from Olifants Letaba confluence July 2010
- Mesenteric fat
- Pectoral fat
SLIDE 25 Pansteatitis in C. gariepinus from Olifants Letaba confluence July 2010
- Intermuscular fat
- Fat surrounding brain
Brain
Fat Muscle
Lesions in fat
SLIDE 26 Steatitis in mesenteric fat of
- C. gariepinus from Olifants Gorge
January 2011
SLIDE 27
Steatitis in mesenteric fat of C. gariepinus Sabiepoort July 2010
SLIDE 28
Steatitis – old and recent lesions in mesenteric fat of C. gariepinus Olifants Letaba confluence January 2011
Granuloma formation – chronic lesion Recent lesion
SLIDE 29 Were the Olifants crocodiles exposed to a single instigating event or is exposure ongoing?
- Findings of the fish health investigation suggest the instigating events
may be common to the Olifants, Letaba and Sabie rivers where these have been dammed.
- Presence of early lesions of fat necrosis, in some cases superimposed
- n chronic lesions, found in the fish at each sampling since 2008
indicate that exposure is ongoing.
