Abstract
To maximise the long-term use of limited ecosystem services in South Africa, managers continually require approaches to optimise the establishment of balances between the use and protection of ecosystems to ensure sustainability. Surface freshwater aquatic ecosystems are dynamic and difficult to manage effectively. Sound management protocols that can identify and rank threats to these ecosystems are urgently required. The Regional-Scale Risk Assessment approach is carried out ona spatial scale and allows for the consideration of multiple sources of multiple stressors affecting multiple endpoints, with the inclusion of local ecosystem dynamics and the characteristics of the landscape that may affect the risk estimate. This paper presents an integrated approach to carry out regional-scale ecological risk assessments using a Relative Risk Model (RRM) adapted for South African conditions. The RRM consists of 10 procedural steps that are relatively easily applied. The use and application of the RRM within South Africa has the potential to provide resource users, resource conservators and regulators of surface aquatic ecosystems with a range of benefits. These benefits include the establishment of a validated,structured methodology that is sensitive to the dynamics of individual case studies, extremely informative, locally applicable and internationally comparable with other RRM assessments. The use of the RRM approach in South Africa has many advantages that outweigh some disadvantages. This approach has the potential to substantially contribute towards the ease and effectiveness of management of the balance between the use and protection of aquatic ecosystems in South Africa.
Highlights
The development of human civilisation has been totally dependent on the use and associated availability of aquatic ecosystem services (Costanza, 1997; Davies and Day, 1998; Palmer et al, 2002)
From a South African perspective, the value of the Relative Risk Model (RRM) lies in its potential to be customised to address the threats of multiple sources of multiple stressors to local habitats and endpoints, thereby contributing towards the objectives of integrated water resource management (IWRM) in South Africa (DWAF, 2004)
The aim of this paper is to present an integrated approach to carry out regional-scale ecological risk assessment (ERA), contributing to the management of freshwater aquatic ecosystems using an adapted RRM with a hypothetical example for South African conditions
Summary
The development of human civilisation has been totally dependent on the use and associated availability of aquatic ecosystem services (Costanza, 1997; Davies and Day, 1998; Palmer et al, 2002). In South Africa and abroad, ecological risk assessment (ERA) methodologies have been established to identify and rank threats to surface aquatic ecosystems in relation to established management objectives (Suter, 1993; Murray and Claassen, 1999; DWAF, 2004). ISSN 1816-7950 (On-line) = Water SA Vol 38 No 2 April 2012 the potential risk of a single or a small number of chemicals impacting on a limited number of ecological endpoints This has historically limited the application of the ERA methodology in complex ecosystems where numerous use activities or sources and associated stressors affect numerous receptors (Claassen et al, 2001). From a South African perspective, the value of the RRM lies in its potential to be customised to address the threats of multiple sources of multiple stressors to local habitats and endpoints, thereby contributing towards the objectives of integrated water resource management (IWRM) in South Africa (DWAF, 2004). We demonstrate the relationship between the existing ERA guidelines and an adapted RRM and demonstrate how locally accepted line-of-evidence methods can be incorporated and applied in the RRM process
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