Why Kruger crocs are croaking

Mining has been blamed for the death of more than 50 crocodiles along the Olifants River in Kruger National Park in the past month.

Autopsies will be performed to reveal the cause of death. The crocodiles may have died from a form of poisoning that hardens their body fat, gradually immobilising them until they starve to death.

The expansion of mining in the area, compounded by the withdrawal of water by a dam in Mozambique, is seen is a possible cause.

“In the past year we’ve seen the effects of unwarranted ground­water extraction by mining companies and pollution from various sources, especially mining,” said Marina Caird of the Wildlife and Environment

“Groundwater helps rivers flow and some rivers have literally stopped flowing. Last year the Olifants River, which has always been perennial, also stopped running.
Mine work extracts six megalitres of water a day, enough to supply 250 000 households.”

Caird said 18 companies mine platinum in the water catchment areas feeding Kruger’s rivers.

Danie Pienaar, Kruger’s head of scientific services, said that the gorge where most of the dead crocodiles were found is being tested for heavy metal pollution.

Dissection of the animals has revealed hardened, orange fat, which is usually a sign of pansteatitis, a poisoning associated with eating rotten fish.

However, there has been no reported “die-off” of fish in the affected area.

Last year six of a population of 15 crocodiles at Loskop Dam died with the same symptoms.

“At Loskop Dam they connected the deaths with the crocodiles’ consumption of rotting fish. We’re obviously not seeing the whole picture,” said Pienaar. “There are other causes of pansteatitis, including heavy metal toxicity.”

He said that he had not detected anything very unusual in water samples from the river.

“The Olifants is historically polluted, going back to when mining effluent used to be dumped into the river, but that’s stopped now. We’re used to a certain level of contamination and nothing has changed in the past year.”

Pienaar said there is concern about the future of the crocodile population in the area and potential harm to human health.

“This is something really serious and of great concern to a lot of people dependent on this river system. I wouldn’t drink any water or eat any fish from the Olifants River.

“Crocodiles don’t die in these numbers for nothing.”

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