Crocodiles are dying off in large numbers in the Olifants river, which is being polluted by various hazardous chemicals, such as acid mine drainage from the mining industry, agricultural chemicals from farms and sewage from urban settlements.

The Department of Environ-mental Affairs and Tourism Deputy Minister Rejoice Mabudafhasi says that the department is well aware of the problems arising at the Olifants river.

“All of these impacts reduce the quality of the water in the system. In many sections of this river, even in the Kruger National Park, the crocodile population is declining. This may result in a serious economic impact as the loss of reptiles could affect tourist attraction and jobs,” she adds.

The media recently reported that 170 crocodiles had been found dead since the ‘first reported’ death occurred last May.

However, Mining Weekly reported on the crocodile death problem last January.

Golder Associates water resource engineer Trevor Coleman tells Mining Weekly that there are many defunct mines in the Olifants river area that should be managed by the Department of Minerals and Energy.

“A number of the mines are impacting on the surface water resources with little attention being given to the management of the impacts by the regulators. Some operational mines are also battling to contain some of the water in their mines, which also spills into the river system. This generally occurs during periods of high rainfall,” says Coleman.

The Loskop dam is an example of how sensitive fish, terrapins, leguaans and crocodiles are to acid-rock drainage. The upslope Olifants river catchment area has been a coal-mining area since the 1890s. The dam, situated below the confluence of the Wilge river and the Olifants river, in Mpumalanga, is home to more than 70 animal species and a variety of fish.

A mixture of elements was found in the upstream end of the dam, which caused mucous to form on the gills of the fish. The mucous also blocks the lungs and they are unable to exchange gas, electrolytes or carbon dioxide, which leads to cardiovascular failure.

After eating the dead fish, the crocodiles’ fatty tissue hardens, which causes a stiffness in the tail, rendering them unable to swim. This is called pansteatitis. Other animals that feed on the rancid fish, such as cats, could also be affected, Coleman adds.

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