Abstract
Rivers in South African are the main source of freshwater, yet the most limited resource in the country. Because they are open water ecosystems, their surrounding environment influenced them greatly as everything happening within the catchment drains into these resources. The Luvuvhu River rises in the Soutpansberg Mountains and is one of the largest rivers that feeds into the Limpopo River. Land-use activities include forestry and agriculture with several Municipal Wastewater Treatment Plants located within the catchment. The studies aim was to measure the ecological state of rivers flowing into Nandoni Dam by assessing the health status of the aquatic macroinvertebrates and riparian zone in the Luvuvhu River catchment. The objectives were 1) to determine the present ecological state (PES) of the Luvuvhu River catchment, 2) to assess the anthropogenic impact on in-stream and riparian habitats and 3) to assess water quality within the catchment.
Biomonitoring was conducted to assess the aquatic health status for the study area. Macroinvertebrates have been used as bioindicators because they are sensitive to change in water quality, easy to sample, distributed widely and found to be accurate. The methods that were used included the assessment of in-situ water quality parameters, assessment of Index of Habitat Integrity and macroinvertebrates assessment using South African Scoring System (SASS5).
The water quality results indicated that all the measured in-situ parameters were within the Target Water Quality Range for aquatic ecosystems. The results indicated that there has been a change from natural state of the water resource with SASS5 results of the five monitored sites ranging from natural (A9LUVU-MALAM) to poor (A9MVUD-MANII). According to the MIRAI results, three of the five sites are in ecological category C namely A9DZIN-CROCO, A9LUVU-HASAN and A9LUVU-NANDO. Ecological category C is a moderately modified category. The fourth site (A9LUVU-MALAM) is in ecological category B/C which is a largely natural category. The fifth and final site (A9MVUD-MANII) is in ecological category C/D which is moderately modified condition but close to a largely modified category D. Therefore, the general PES of Luvuvhu River is in an ecological category C.
Overall, the river is in a largely natural to moderately modified (B/C) category resulting from anthropogenic activities however the system functioning remains intact, still providing its services. Strong government, private and public inter-relations are required to promote the values of our water resources to ensure that these resources are managed, used, protected, and conserved in a manner that will promote its maintenance for the benefits of present and future generations.