Non-invasive assessment of trace elements to evaluate African savannah ecosystem health

Abstract

The substantial differences in geological and geochemical heterogeneity, combined with gradients in precipitation, vegetation and climatic conditions result in the natural distribution of trace elements at different spatial intensities at local, regional and global scales. The increased demand for and utilisation of trace elements to meet the growing needs of the global population however have resulted in widespread contamination of the environment. Protected areas and the biodiversity they support are not excluded from the effects of trace element pollution and species within specific areas may be exposed to complex, Ill-defined mixtures of pollutants. The sequential and simultaneous exposure of wildlife to these mixtures from direct, indirect, past or contemporary exposures on a continuous basis, interact in additive or synergistic ways to disrupt endocrine function and other biological functions, resulting in subsequent cascading effects.

Biomonitoring lies at the core of ecosystem management, restoration and conservation and has become an indispensable tool for the study of wildlife and environmental exposure to specific contaminants and pollution in general. The management plans for conservation and protected areas within South Africa do not include regular monitoring and risk assessment of potentially toxic elements and chemical compounds. Additionally, traditional methods of toxicological risk assessment in wildlife are typically invasive (opportunistic collection from carcasses after mortality or debilitation events, laboratory studies or chemical immobilisation of live animals). A non-invasive approach that facilitates risk assessment of multiple abundant, elusive and endangered species at different trophic levels within their specific environments would be advantageous.

Overall, the evaluation and comparison of trace elements in multiple matrices and numerous sampled locations within and between sites facilitated a more comprehensive understanding of trace element availability, deficiency and utilisation in protected areas and resident wildlife. Risk factors and recommended avenues for future research have been identified. The complex factors associated with trace element risk assessment should be approached from a multi-disciplinary perspective given geological, anthropogenic and species-specific differences.