Diatom-based water quality monitoring in southern Africa: challenges and future prospects

Tatenda Dalu,P William Froneman

doi:10.4314/wsa.v42i4.05

Abstract

Diatoms are of significant ecological importance in aquatic ecosystems, which stems from their dynamic position at the base of the trophic web as primary producers. Because diatom communities have specific environmental requirements and respond rapidly to changes in environmental conditions they are often employed as a cost-effective method to assess anthropogenic impacts and health statuses of aquatic ecosystems, particularly in Europe and North America. The purpose of this review is to summarise the challenges and future prospects associated with biological water quality monitoring using diatoms with special focus on southern Africa. Much work still needs to be carried out on diatom tolerances, ecological preferences and ecophysiology. It is recommended that past research pertaining to African diatom taxonomy should be made readily accessible to all through electronic media for use as a reference point. Moreover, following the same approach as for macroinvertebrate biomonitoring, African and other developing countries can resort to intermediate diatom taxonomy (i.e. genus), which is easier, less time-consuming and requires less-skilled personnel. While the lack of capacity and baseline information on diatom community composition and ecological requirements represent significant hurdles, diatom biomonitoring potentially holds much promise for understanding the ecological functioning and management of aquatic ecosystems in southern Africa. The application of diatom-based water quality assessment protocols has direct and immediate value for use as an ‘added-value’ assessment tool in addition to the use of macroinvertebrates and fish indices as these can indicate anthropogenically impacted and pristine sites. Keywords: application, biomonitoring, ecology, taxonomy, rivers, water quality

Highlights

Aquatic ecosystems form a fundamental component of global biogeochemical cycles, acting as transport pathways, elemental transformations and storage sites (Wehr and Descy, 1998; Bere and Tundisi, 2010)
The purpose of this review is to summarise the challenges and prospects for employing diatoms as a biomonitoring tool in water quality monitoring, with specific focus on the sub-Saharan African region
Diatom-based biomonitoring programmes have been implemented with some success in Kenya, South Africa, Zambia and Zimbabwe

Summary

Introduction

Aquatic ecosystems form a fundamental component of global biogeochemical cycles, acting as transport pathways, elemental transformations and storage sites (Wehr and Descy, 1998; Bere and Tundisi, 2010) These systems are characterised by a high degree of interaction and complexity among physical, chemical and biological processes. An important feature of aquatic ecosystems is that a disturbance at one location, through conversion of landscapes into other uses such as agriculture, urban and industrial developments, often affects the functioning, processes and organisms downstream. This has serious implications for ecosystem functioning and for management of these systems (Ndaragu et al, 2004; Ndiritu et al, 2006). Information on the impacts of anthropogenic activities in river systems is well documented in developed countries (e.g. Dixit and Smol, 1994; Kelly et al, 2008, 2012; Stevenson, 2014), very little is known from most developing countries, yet such data are important for developing appropriate management practices (Fabricius et al, 2003; De la Rey et al, 2004, 2008; Taylor et al, 2007a; Bere and Tundisi, 2010) necessary to meet Millennium Development Goal 7, on ensuring environmental sustainability

Objectives

Conclusion