Investigating an aquatic system as a route of entry for multiple environmental contaminants into Kruger National Park, South Africa

Kruger National Park (KNP) is a 2 million hectare protected area, and a UNESCO World Heritage Site, inhabited by hundreds of mammalian species (including lions, leopards, rhinos, elephants and buffalos) and avian species (including numerous vulture, eagle and stork species), with many species of conservation importance. However, while national legislation protect the terrestrial boundaries of the park, environmental pollutants can enter by a number of rivers, particularly the Olifants River. The Olifants River begins in the Highveld region, flowing north-north-east, through KNP, and ultimately enters Mozambique. Along its length outside KNP, contaminant sources include: coal and metal mining (adding acid wastewater and heavy metals), areas of irrigated agriculture (with runoff, containing pesticides and fertilisers), and several towns and cities (adding untreated wastewater). The co-location of these sources of contamination, and this unique conservation area, facilitates a study exploring the health of the ecosystem and the animals living in these contrasting landscapes, which have been variably influenced by anthropogenic activities.

In 2008 and 2009, and sporadically since then, dieoffs of Nile crocodiles and Mozambique tilapia occurred at a number of sites along the Olifants. Pansteatitis, an inflammatory condition of fat tissue, was identified in both species as the cause of death. A definitive cause has not been determined, but it has been suggested that organic and/or inorganic contaminants in the river system deplete free oxygen radical scavengers in these animals, reducing their ability to metabolise dietary fatty acids, resulting in pansteatitis.

The proposed study involves assessing levels of organic and inorganic contaminants in sediment, water and invertebrates, fish and crocodiles at sites along the Olifants River system within and outside KNP, and health of the fish and crocodiles. This will enable assessment of the distribution and bioavailability of contaminants throughout multiple trophic levels, and their potential impact on animal health.