Fish and habitat present ecological state in the Mooi River catchment in the North West Province

Abstract

Anthropogenic activities are important for various purposes such as economic activities, recreation and to partially safeguard food and energy across the world. In a semi-arid country such as South Africa, where the freshwater resources are already vulnerable and threatened by drought and deteriorating water quality, the catchment conditions are a major concern contributing to ecological status decline. The potential impact on fish species and habitat associated with anthropogenic activities that change catchment conditions are extensive and devastating. Therefore, the aim of this study was to assess the fish and habitat integrity representing the ecological status of the Mooi River located in the North-West Province. The fish species were assessed during austral spring in October 2018 together with the habitat integrity. The Fish Response Assessment Index and Index of Habitat Integrity (IHI) were used to determine Present Ecological State (PES) and habitat indicators linked to fish species. A Principal Component Analysis (PCA) and unconstrained ordination were used to determine the temporal and spatial variation of landscape and soil properties for fish species. The results showed that there is an abundance of anthropogenic activities which change catchment conditions and the in-channel and bank conditions are modified. The in-stream and riparian zone integrity scores were between 40-59% and 60-79% placing it to category D or C/D. The results for overall fish PES were 52, placing it in category D, therefore, largely modified. The results of the habitat integrity and PES are within the recommended limit of Resource Quality Objectives (RQOs). The results of the PCA and unconstrained ordination indicated temporal variation at Sites 2 and 3 as well as sites 4, 5 and 6 which were grouped together. Site 1 varied spatially and grouped separately due to increased changes in landscape. The PES across all sampling sites is moderately to largely modified, therefore there is a great need to continuously monitor the catchment and alert community and stakeholders on possible activities that may trigger a critical modified environment.