PANSTEATITIS OF UNKNOWN ETIOLOGY ASSOCIATED WITH LARGE-SCALE NILE CROCODILE (<i>CROCODYLUS NILOTICUS</i>) MORTALITY IN KRUGER NATIONAL PARK, SOUTH AFRICA: PATHOLOGIC FINDINGS

Mitchell, Emily; Huchzermeyer, F. W.; Govender, Danny; Bengis, Roy G.; Buss, Peter; Hofmeyr, Markus; Myburgh, Jan G.; Steyl, Johan Christian Abraham; Pienaar, Daniel J.; Kotzé, Antoinette

doi:10.1638/2012-0264r.1

Cited by 26 publications

(23 citation statements)

References 42 publications

(52 reference statements)

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“…In 2008, KNP in South Africa experienced numerous mortalities to its resident Nile crocodile population in the Olifants River, with another episode of mortalities following in the spring of 2009. The mortality events of the crocodiles, as well as other aquatic species, were attributed to environmental pansteatitis, a disease hallmarked by inflammation and subsequent hardening of adipose tissue (Osthoff et al, 2010; Huchzermeyer et al, 2013; Lane et al, 2013). To date, no definitive origin of for pansteatitis has yet been determined, though several hypotheses have been noted, which include possible contributions from anthropogenic sources (Larsen et al, 1983; Swanepoel et al, 2000; Ashton, 2010; Masango et al, 2010; Huchzermeyer et al, 2011; Oberholster et al, 2012; Woodborne et al, 2012; Dabrowski et al, 2013; Bouwman et al, 2014; Dabrowski et al, 2014).…”

Section: Resultsmentioning

confidence: 99%

Perfluorinated alkyl acids in the plasma of South African crocodiles (Crocodylus niloticus)

et al. 2016

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Perfluorinated alkyl acids (PFAAs) are environmental contaminants that have been used in many products for over 50 years. Interest and concern has grown since 2000 on the widespread presence of PFAAs, when it was discovered that PFAAs were present in wildlife samples around the northern hemisphere. Since then, several studies have reported PFAAs in wildlife from many locations, including the remote regions of Antarctica and the Arctic. Although there are a multitude of studies, few have reported PFAA concentrations in reptiles and wildlife in the Southern Hemisphere. This study investigated the presence of PFAAs in the plasma of Nile crocodiles (Crocodylus niloticus) from South Africa. Crocodiles were captured from five sites in and around the Kruger National Park, South Africa, and plasma samples examined for PFAAs. Perfluorooctane sulfonate (PFOS) was the most frequent PFAA detected; with median values of 13.5 ng/g wet mass in crocodiles. In addition to PFOS, long chain perfluorinated carboxylic acids were also detected. Correlations between total length and PFAA load were investigated, as were differences in PFAA accumulation between sexes. No correlations were seen between crocodile size, nor were there sex-related differences. Spatial differences were examined and significant differences were observed in samples collected from the different sites (p < 0.05). Flag Boshielo Dam had the highest PFOS measurements, with a median concentration of 50.3 ng/g wet mass, when compared to the other sites (median concentrations at other sites below 14.0 ng/g wet mass). This suggests a point source of PFOS in this area.

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Section: Resultsmentioning

confidence: 99%

Perfluorinated alkyl acids in the plasma of South African crocodiles (Crocodylus niloticus)

et al. 2016

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“…The disease pansteatitis has been identified as a leading cause of declining natural populations of Nile crocodiles Crocodylus niloticus (Laurenti) along the Olifants River in South Africa (Ashton 2010;Ferreira & Pienaar 2011;Lane et al 2013). A high prevalence of pansteatitis has also been documented in certain species of fish at several localities where the Olifants River has been dammed to make impoundments (Huchzermeyer et al 2011;Huchzermeyer 2012;Woodborne et al 2012;Dabrowski et al 2013Dabrowski et al , 2014Bowden et al 2016).…”

Section: Introductionmentioning

confidence: 99%

Pansteatitis in polluted Olifants River impoundments: nutritional perspectives on fish in a eutrophic lake, Lake Loskop, South Africa

Huchzermeyer

Woodborne

Osthoff

et al. 2017

Journal of Fish Diseases

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This study compares the aetiology of pansteatitis in Lake Loskop, relative to two other impoundments along the Olifants River. Macroscopic and microscopic pathology, age determination and analysis of stomach content, fatty acids and stable isotopes explain the high prevalence of pansteatitis in Oreochromis mossambicus (Peters) and several other species in Lake Loskop. All the dietary indicator comparisons between pansteatitis-affected and healthy fish fail to support a systemic cause. Pansteatitis in Lake Loskop was linked to size and weight of O. mossambicus, but not to ontogenic age. Fish in Lake Loskop showed abnormally high omega-3 to omega-6 fatty acid ratios normally only found in marine fish with no significant difference in degree of assimilation of these fatty acids between pansteatitis-affected and healthy fish. This explains the vulnerability to, but not the occurrence of, pansteatitis. As a cause for the pansteatitis, these results point towards sporadic vitamin E-depleting trigger events, known sporadic fish die-off occurrences that provide surviving fish with a rich source of rancid fats on which to scavenge. The mechanism ties pansteatitis to eutrophication and trophic cascade effects, the intrinsic drivers of the disease and suggests an adaptive management strategy that might be applied by relevant conservation authorities.

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“…Trade in captive-bred Nile crocodile products is legal under the Convention on International Trade in Endangered Species (CITES) (Luxmoore, 1992). No harvesting of crocodile eggs from the wild is allowed in South Africa as wild Nile crocodile populations are declining (Ashton, 2010;Combrink et al, 2011;Lane et al, 2013). All commercial farm crocodile offspring come from breeding stock kept on commercial farms (captive-bred approach).…”

Section: Introductionmentioning

confidence: 99%

Vertical transmission of microcystins to Nile crocodile ( Crocodylus niloticus ) eggs

Singo

Myburgh

Laver

et al. 2017

Toxicon

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Cyanobacteria or blue green algae are known for their extensive and highly visible blooms in eutrophic, stagnant freshwater bodies. Climate change and global warming have also contributed to a rise in toxic cyanobacterial blooms. One of the most important cyanobacteria is Microcystis aeruginosa, which can synthesize various microcystins that can affect the health of terrestrial and aquatic animals. Commercial Nile crocodile (Crocodylus niloticus) farming in South Africa is based on keeping breeders (adult males and females) in big dams on farms (captive-bred approach). Unfortunately, cyanobacterial blooms in the breeder dams are a concern to farm owners, managers and veterinarians. The main objectives of this research project were to determine if microcystins were present in the contents of crocodile eggs and the liver and yolk of dead hatchlings, and to determine if the reduced hatchability on commercial farms might be caused by these toxins. Furthermore, the concentration of microcystins in the breeder dam was monitored on a monthly basis spanning the ovulation and egg laying period. During the hatching season microcystin concentrations in unfertilised eggs, egg shell membranes and in the yolk and liver of dead hatchlings were determined using liquid chromatography-high resolution mass spectrometry (LC-HRMS). Microcystins were detected in Nile crocodile egg and hatchling samples. Microcystin (MC-LR, MC-RR, MC-YR) concentrations in the crocodile egg and hatchling samples collected from clutches with a good hatching rate (≥90%) ranged between 0 and 1.76 ng g, with the highest concentration in the egg shell membranes. Microcystin concentrations in samples collected from clutches with a bad hatching rate (≤10%) ranged from 0 - 1.63 ng g with the highest concentration detected in the hatchling yolk. However, the concentrations were probably underestimated as the percentage recovery from spiked samples was very low with the extraction method employed. Bayesian analysis suggests that the liver, yolk and unfertilised egg all have similar microcystin concentrations, while the membranes have (with moderate to high certainty) higher microcystin concentrations. There appears to be no difference in microcystin concentrations among good and bad clutches across all tissue types or within a specific tissue type, but due to the small sample size, it was not possible to determine whether microcystin affected the hatchability of Nile crocodile eggs. However, vertical transmission of microcystin variants to the Nile crocodile egg does occur and the possible implications for the survival of wild Nile crocodile populations should be ascertained.

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PANSTEATITIS OF UNKNOWN ETIOLOGY ASSOCIATED WITH LARGE-SCALE NILE CROCODILE (CROCODYLUS NILOTICUS) MORTALITY IN KRUGER NATIONAL PARK, SOUTH AFRICA: PATHOLOGIC FINDINGS

Cited by 26 publications

References 42 publications

Perfluorinated alkyl acids in the plasma of South African crocodiles (Crocodylus niloticus)

Perfluorinated alkyl acids in the plasma of South African crocodiles (Crocodylus niloticus)

Pansteatitis in polluted Olifants River impoundments: nutritional perspectives on fish in a eutrophic lake, Lake Loskop, South Africa

Vertical transmission of microcystins to Nile crocodile ( Crocodylus niloticus ) eggs

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