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

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.

Development of a diatom-based multimetric index for acid mine drainage impacted depressional wetlands

“…Our results are also consistent with those for macroinvertebrate assemblages (Firmiano et al, 2017;Silva et al, 2016;Whittier and Van Sickle, 2010). Genus-level taxonomy does not require high-level species identification which can be time consuming and require specialised taxonomic expertise, which in South Africa is largely lacking (Dalu and Froneman, 2016). The use of genus-level metrics may therefore allow for a simplified, time and cost effective assessment of wetland condition while maintaining important ecological information.…”

Benthic Diatoms in River Biomonitoring—Present and Future Perspectives within the Water Framework Directive

“…In Australia, phytobenthos has been used for biological quality assessment for many years before the implementation of WFD in Europe (e.g., [91]); however, there has been no governmental coordination [90]. In Africa, South Africa has a long legacy of diatom research and use in biomonitoring; however, greater effort is needed for organized implementation in other African countries [92]. In Asia, the Asian Pacific Water Summit in 2007 started a new era in water quality assessment in Asian countries [93] The need for global application of bioassessments influenced by WFD is apparent; however, further discussion deviates from the scope of the present review.…”

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

“…Diatoms form thick biofilms in South Africa during the winter months and are major contributors to primary production. Diatoms are extremely useful ecological indicators (De la Rey 2004; Bate et al 2004;Harding et al 2005;Harding & Taylor 2014;Mangadze et al 2015;Dalu & Froneman 2016). Additionally, diatoms are not geographically limited and their distribution is chiefly driven by water quality.…”