Diatom responses to river water quality in the Kruger National Park, South Africa

Danny Govender,Jonathan C Taylor,Purvance Shikwambana,Judith Botha

doi:10.38201/btha.abc.v51.i1.5

Abstract

Background: Although the Kruger National Park (KNP) is a protected area, it is not exempted from anthropogenically induced impacts, which often compromise river water flow and quality. Measures of river water quality in South Africa have conventionally been based on water chemistry as well as different ecological indicator groups such as fish and macroinvertebrates. Diatoms have been shown to be useful indicators of changes in water quality resulting from pollution and land-use impacts.Objectives: To determine the applicability of diatoms for hind-casting water quality in the KNP and to compare recent diatom community composition with those from the 1980s.Methods: In this study, pH and electrical conductivity (EC) were used to evaluate temporal changes in water quality of three rivers within the KNP. Additionally, we made use of historic diatom samples from three of the five perennial rivers to evaluate if diatom communities reflected changes in water conditions between 1983 and 2015.Results: Diatom community structure was significantly different between 1983 and 2015. Diatom-based index scores (SPI) indicated an improvement in water quality for the Letaba and Olifants rivers.Conclusion: Diatoms were shown to be useful indicators of current water quality and are also useful for determining temporal changes.

Highlights

We evaluated the potential of diatoms as water quality indicators by studying changes in diatom community structure in relation to electrical conductivity (EC) and pH
Our results did not show a significant increase in EC or a change in pH during the period (Figure 2) of the study, diatom based observations, suggest that the Letaba River has improved in water quality between the two study periods
The present study showed that EC values have changed over the decades as has the associated diatom community structure, reflected by SPI scores

Summary

Introduction

They are the main sources of available surface water in many countries including South Africa. Less than 0.3% of all the available surface water is freshwater (Griffiths et al 2015) This portion of water is reported to be on a decline both in quality and quantity (Pillay & Buckley 2001; Roux & Nel 2012; Laine et al 2014). Five perennial rivers flow through the Kruger National Park (KNP) and the KNP is a protected area, its rivers are not exempt from anthropogenically induced impacts that compromise water quality and flow (Dallas & Day 2004; Pollard et al 2011). The Kruger National Park (KNP) is a protected area, it is not exempted from anthropogenically induced impacts, which often compromise river water flow and quality. Diatoms have been shown to be useful indicators of changes in water quality resulting from pollution and land-use impacts

Objectives

Methods

Results

Discussion

Conclusion