INTRODUCTION • The Olifants River in the Kruger National Park has one of the largest Nile crocodile (Crocodylus niloticus) populations in Africa. • May to September 2008: Massive crocodile mortalities (at least 160) in the Olifants River gorge area (Fig. 1). • Post mortem examinations - yellow-orange hardened fat in their tails & elsewhere. • Condition known as pansteatitis. • Pansteatitis = Normally a nutritionally mediated condition, associated with high- unsaturated fatty acid, low-vitamin E diet, causing depletion of the anti-oxidant system, leading to lipid peroxidation and deposition of ceroid pigment [1]. • Hardened fat is unavailable for metabolism, leading to extreme pain & reduced mobility. • Impediment of swimming or hunting eventually leads to starvation or drowning. • Causes for Olifants River mortality is UNKNOWN. • Hypothesis : Possible substances having the potential to cause or contribute to pansteatitis: - Organochlorine pesticides - Heavy metals - PAHs - Dioxin-like chemicals - Acrylamide - Creosotes • Analysis done by NILU & NWU: Dioxin-like chemicals, organochlorine pesticides, PAHs & heavy metals in sediments & fat tissue from affected crocodiles. MASS DEATHS OF CROCODILES IN THE KRUGER NATIONAL PARK, SOUTH AFRICA: AN INVESTIGATION INTO POSSIBLE CAUSES. Claudine Nieuwoudt 1 , Laura Quinn 1 , Rialet Pieters 1 , Ellen-Katrin Enge 2 , Henrik Kylin 3 , Danie Pienaar 4 & Henk Bouwman 1 1 School of Environmental Sciences and Development, North-West University (NWU), Potchefstroom Campus, Private Bag X6001, Potchefstroom 2520, South Africa. 2 Norwegian Institute for Air Research (NILU), P.O. Box 100, NO-2027 Kjeller, Norway. 3 Norwegian Institute for Air Research, The Polar Environmental Centre, NO-9296, Tromsø, Norway. 4 Kruger National Park, South African National Parks, Private Bag X402, Skukuza, 1350. MATERIALS & METHODS A. Collection of sediment & tail fat – August 2008. B. Extraction with Soxhlet Apparatus. C. Analysis of sediment & fat samples [2]. Gas chromatography-high resolution mass spectrometry (GC-HRMS) Sediment: HCH, DDT, PBDEs, PAHs, PCDD/Fs & PCBs. Crocodile fat: DDE, DDD & DDT, Methylsulphone DDE & -PCBs. Inductively coupled plasma-mass spectrometry (ICPMS) Sediment: Trace & heavy metals Crocodile fat: Trace & heavy metals CONCLUSIONS • Traces of dioxin-like substances, pesticides (DDT & HCH), PAHs & PBDEs, and “normal” levels of trace & heavy metals in both sediment and fat tissue. • Generally, levels were below recommended sediment quality guidelines. • The prime single cause of crocodile mortalities is still UNKNOWN, but it is speculated that the crocodile deaths are triggered by a combination of factors – environmental & dietary. • The problem has stabilized and crocodiles are not dying at the previous rate. • Investigations into the cause(s) and effects are continuing. • Mortalities might resume if related to onset of winter. REFERENCES 1. Halliwell, B. & Chirico, S. 1993. Lipid peroxidation: its mechanisms, measurement, and significance. The American Journal of Clinical Nutrition 57 (Suppl): 715S – 723S. 2. US EPA. 1994. Method 1613: Tetra- through octa-chlorinated dioxins and furans by isotope dilution HRGC/HRMS. Revision B. Office of Water: Engineering and Analysis Division. Washington, DC. EPA-821-B-94-005. 3. Canadian Council of Ministers of the Environment. 2008. www.ccme.ca Nelspruit Hazyview Phalaborwa Massingir Dam MOZAMBIQUE ZIMBABWE KRUGER NATIONAL PARK Limpopo Limpopo Olifants River 0 Km 30 Komati River Sabie River Mbyamiti Olifants River Mutale Luvuvhu Shisha Crocodile River Emlambeni Nwaswitshaka Timbavati Nhlaralumi Sweni Sand River Nwaswitsonto Letaba Ngwenyeni Tsende Byashishi Lesser Letaba Nalatsi Shingwidzi Mphongolo Greater Letaba 11-12 13 14-15 10 16 6-9 17-19 4-5 1-3 Fig. 1: Sites sampled in the Kruger National Park, South Africa. The Olifants River gorge is indicated in red. Fig. 2: Investigations into mass deaths of crocodiles in the Kruger National Park. Post mortem examinations revealed that crocodiles were affected by pansteatitis. RESULTS & DISCUSSION A. Organochlorine pesticides, dioxin-like chemicals, PAHs & PBDEs Sediment • GC-HRMS results: Levels in sediments were generally low (Fig. 3-4). • Few sites exceeded the Canadian recommended sediment quality guidelines [3] (Fig. 3-4). Tail fat • Fat samples were analysed for DDT, DDD, DDE-, & methylsulphone DDE & -PCBs. • Levels of all targeted chemicals, except DDD, DDE & DDT (Fig. 5) were below the detection limit. B. Trace & heavy metals • Levels of trace & heavy metals in sediment & crocodile fat were low (Table 1). • Aluminium (Al) & iron (Fe) were the dominant metals in both sediment & fat. Table 1. Levels of selected heavy metals in sediments & crocodile fat. Fig. 5: Levels of DDE, DDD & DDT measured in tail fat. Olifants gorge Reference area Olifants River Letaba River Crocodile 3 Olifants/Letaba Crocodile 4 Olifants River Crocodile 5 Letaba River Al 2000 220 640 1800 61 1.8 4.4 As 0.29 0.11 0.12 0.26 0.24 0.17 0.16 Cd 0.0024 0.0012 0.0014 0.004 1.20E-03 0.0025 0.0025 Cr 14 2.7 2.7 12 0.1 0.1 0.11 Co 2.2 0.38 0.52 2.1 0.0072 0.0065 0.012 Cu 3.2 0.66 0.54 3 0.21 0.13 0.35 Fe 2700 570 1000 2600 11 8.3 18 Hg 4.00E-04 4.30E-04 3.40E-04 2.80E-04 5.10E-04 1.20E-03 6.20E-04 Mn 66 6.4 9.2 66 0.22 0.23 0.28 Ni 8.3 1.6 1.6 7.5 0.05 0.043 0.074 Pb 0.49 0.12 0.11 0.5 0.024 0.024 0.026 V 5 1.9 4.5 4.7 0.049 0.03 0.038 Zn 2.8 0.78 0.86 2.6 0.79 2.2 1 Heavy metals (mg/kg) Sediment Crocodile fat Fig. 3 & 4: Levels of certain organic pollutants measured in sediments from the Kruger National Park. (Levels exceeding Canadian interim sediment quality guidelines* or probable effect levels** [3]). 0 50 000 100 000 150 000 200 000 250 000 300 000 RioIncomati Komati Crocodile Sabie OlifantsGorge Reference Letaba Luvuvhu LowerLetaba Olifants Sampled rivers Concentration of PAHs (ng/kg) * * * * ** * * * * * * 0 2000 4000 6000 8000 10000 12000 14000 RioIncomati Komati Crocodile Sabie OlifantsGorge Reference Letaba Luvuvhu Lower Letaba Olifants Selati Sampled rivers Concentration (ng/kg) HCH DDT PCB PBDE Dioxin-like chemicals 0 1 2 3 4 5 6 Crocodile 1: Male Crocodile 2: Female Tail fat samples Concentration (mg/kg) p,p’-DDE p,p’-DDD p,p’-DDT