A cross-sectional assessment of fish populations and bacterial contamination in the uMngeni, uThukela, Umvoti, Umdloti, and Umfolozi Rivers, KwaZulu-Natal.

Sibonelo Thanda Mbanjwa

doi:10.51168/sjhrafrica.v6i6.1844

Authors

Sibonelo Thanda Mbanjwa Mangosuthu University of Technology

DOI:

https://doi.org/10.51168/sjhrafrica.v6i6.1844

Keywords:

Fish biodiversity, E. coli contamination, freshwater ecosystems, river health, KwaZulu-Natal, biomonitoring, ecological integrity, anthropogenic impact, water quality, conservation management

Abstract

Background
Freshwater rivers in KwaZulu-Natal are essential for biodiversity, human well-being, and ecosystem services. However, increasing anthropogenic pressures, including wastewater discharge, agricultural runoff, and urban development, have raised concerns over declining fish biodiversity and rising bacterial contamination. Fish serve as indicators of long-term ecological health, while Escherichia coli (E. coli) reflects immediate public health risks.

Methods

A cross-sectional field study was conducted in 2024 across five rivers: uMngeni, uThukela, Umvoti, Umdloti, and Umfolozi. Sampling occurred at upstream, midstream, and downstream sites. Fish were collected using electrofishing and gill nets, identified to species level, and evaluated for diversity, abundance, and trophic group. Water samples were analyzed for total coliforms and E. coli using membrane filtration per SANS 241 guidelines. Descriptive statistics and ANOVA were used to test spatial trends and site differences.

Results

Fish diversity and abundance varied significantly across rivers and sites. The uMngeni and Umvoti Rivers recorded the lowest species richness, particularly downstream, indicating pollution and habitat degradation. In contrast, the Umdloti and Umfolozi Rivers showed greater diversity. Carnivorous and omnivorous species dominated impacted sites, while sensitive species occurred in less disturbed rivers. Bacterial analysis revealed elevated E. coli levels in downstream areas, with uMngeni and Umvoti sites exceeding safety thresholds (>1,000 CFU/100ml), posing health risks to local communities.

Conclusion

Marked ecological variation was observed among KwaZulu-Natal rivers. Reduced fish diversity and elevated bacterial loads in heavily impacted rivers indicate deteriorating ecological and public health conditions.

Recommendation

Integrated monitoring programs should combine biological and microbial indicators. Pollution control, wastewater treatment, agricultural buffers, and riparian restoration are essential. Promoting community-based awareness and catchment management will support long-term river conservation and sustainable use.

Author Biography

Sibonelo Thanda Mbanjwa, Mangosuthu University of Technology

Dr. Sibonelo Thanda Mbanjwa is a dedicated lecturer in the Department of Nature Conservation at Mangosuthu University of Technology (MUT), South Africa. He holds a Ph.D. in Environmental Science and specializes in biodiversity conservation, sustainable development, and environmental education. Dr. Mbanjwa is deeply committed to community engagement, student mentorship, and the integration of indigenous knowledge systems into conservation practices. His work bridges academia and practical application, empowering students and communities through innovative teaching, research, and outreach initiatives.

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