Diatom Assemblages in the Mnweni River System in KwaZulu-Natal, South Africa

Microalgae of benthic origins are abundant in aquatic ecosystems which have been affected by anthropogenic factors and provide a valuable aid in determining water quality. This study was initiated to understand the changes that occurred in the microphytobenthos diatom community in the pristine Mnweni river system in the KwaZulu-Natal Drakensberg region. Diatom frustules were examined under an Olympus BX41TF light microscope with Differential Interference Contrast (DIC) optics. The PRIMER v5 computer software package was utilised to perform multivariate data analyses which included clustering, ordination and k-dominance curves. The diatom Cymbella turgidula was present in all five sites whilst Encyonopsis stafsholtii was abundant in sites three and four. A SIMPER analysis of the data showed an average dissimilarity between the sites. Sites with higher total dissolved solids (TDS), phosphorous and nitrogen showed suppressed pH values although all values were above seven. The diatom composition together with environmental gradients in the catchment suggests that river chemistry, environment structure, current pattern and terrestrial use had important impacts on the integrity of the system. The diatom species that were found in the study sites suggested that the water in the Mnweni catchment was clean or mildly enriched. (c) 2018 Friends Science Publishers