An overview of cyanobacterial research and management in South Africa post-2000

Harding, W. R.; Downing, Tim G.; Ginkel, C. E. van; Moolman, Allan

doi:10.4314/wsa.v35i4.76792

Cited by 18 publications

(14 citation statements)

References 18 publications

(5 reference statements)

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“…Thus monitoring of the quality of its water is a primary priority for public health. However, on a daily basis, this reservoir receives millions of litres of treated wastewater that is rich in phosphates and nitrogenous species, this has led to excessive nutrient loading resulting in Hartbeespoort Dams being one of the most heavily eutrophied dams in South Africa [65,66]. Eutrophication of this dam dates back to beyond the 1970s and the water is quite often characterised by foul smell and heavy green pigmentation especially during summer seasons [67].…”

Section: Resultsmentioning

confidence: 99%

Quantitative Variations of Intracellular Microcystin-LR, -RR and -YR in Samples Collected from Four Locations in Hartbeespoort Dam in North West Province (South Africa) During the 2010/2011 Summer Season

Mbukwa

Msagati

Mamba

2012

IJERPH

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The Hartbeespoort (HBP) Dam is a reservoir used for agricultural, domestic supply of raw potable water and recreational activities in South Africa’s North-West Province. Eutrophication and cyanobacterial blooms have long been a cause of water-quality problems in this reservoir. The most prevalent bloom-forming species is Microcystis aeruginosa, often producing the toxin microcystin, a hepatotoxin which can negatively impact aquatic animal and human health, and poses a problem for potable water supply. Algal samples were collected monthly from four pre-determined sites in the dam during the summer months (December 2010–March 2011). Intracellular microcystins (MCs) were extracted using SPE C18 cartridges, followed by separation, identification and quantification using LC-ESI-MS techniques. Quantitative variation studies of MCs were conducted with respect to MC congener isolated, sampling site and month. Three main MC congeners (MC-RR, -LR and-YR) were isolated, identified and quantified. In addition, three minor MCs (MC-WR, MC-(H4)YR and (D-Asp3, Dha7)MC-RR were also identified, but were not quantified. The MC dominance followed the order MC-RR>MC-LR>MC-YR across all sites and time. The maximum and minimum concentrations were 268 µg/g and 0.14 µg/g DW for MC-RR and MC-YR, respectively, of the total MCs quantified from this study. One-way ANOVA showed that there were no significant differences between average MC concentrations recorded across months (P = 0.62), there was, however, a marginally-significant difference in concentrations among MC congeners (P = 0.06). ANCOVA revealed a highly significant interaction between sites and MC congeners on MC concentration (P < 0.001).

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Section: Resultsmentioning

confidence: 99%

Quantitative Variations of Intracellular Microcystin-LR, -RR and -YR in Samples Collected from Four Locations in Hartbeespoort Dam in North West Province (South Africa) During the 2010/2011 Summer Season

Mbukwa

Msagati

Mamba

2012

IJERPH

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“…At least 35% of water stored in such reservoirs is already classed as eutrophic or hypertrophic, with an additional 30% bordering on the eutrophic status (Harding et al, 2009). Since this nutrient pollution is largely attributable to wastewater effluents (Harding, 2008), the problem can be constrained by enforcing appropriate wastewater treatment and effluent discharge restrictions.…”

Section: Introductionmentioning

confidence: 99%

Food-web structure in the hypertrophic Rietvlei Dam based on stable isotope analysis: Specific and general implications for reservoir biomanipulation

Harding¹,

Hart²

2013

WSA

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Fish predation on zooplankton is the basic foundation for top-down biomanipulation of lacustrine ecosystems. To test this premise, we determined stable isotope (SI) values (δ 13 C and δ 15 N) of representative samples of major planktonic (phytoplankton, zooplankton), benthic (submerged macrophytes and associated epiphytes, benthic macro-invertebrates) and nektonic (fish) food-web components, collected from 3 to 7 shallow inshore locations (with additional plankton samples at 1 or 2 deep offshore sites) in Rietvlei Dam over a period of 30 months. The resulting δ 13 C values did not indicate significant consumption of zooplankton by fish, while the δ 15 N values for fish confirmed their wide trophic separation from zooplankton. Instead, SI values indicated that fish relied mostly on food resources of benthic origin (through direct consumption or piscivory). The SI signatures of individual fish species were consistent with their known feeding habits. The lack of trophic couplings between zooplankton and fish accords with previous gut content analyses of fish and analyses of zooplankton abundance and size structure in hypertrophic reservoirs. Marginal utilisation of zooplankton by indigenous reservoir fish is attributable to their native origin as riverine species unaccustomed to feeding on zooplankton. These findings indicate that top-down biomanipulation is unlikely to be effective as a management tool in eutrophic South African reservoirs. Primary producer components exhibited surprisingly wide and unsystematic temporal fluctuations in both δ 13 C and δ 15 N values; some potential contributory factors are considered. Changes in phytoplankton δ 13 C values were broadly tracked by zooplankton -their nominal consumers. Some questions arising from the study, and some apparently anomalous findings are identified and discussed.

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“…WRI, 2000), extant concerns increasingly highlight the problem of eutrophication and the compounding problem of pharmaceuticals, endocrine disrupting compounds (EDCs), pathogens, pro-inflammatory activity, pesticides and/or heavy metals in South African reservoirs and rivers, especially where urban runoff and wastewater effluents form a substantial component of the water balance (e.g. Harding, 2010, cited in Kidd, 2011Wose Kinge et al, 2010;Nyirenda et al, 2011;Siri et al, 2011;WHO, 2012a-c;Adebayo et al, 2014;Naidoo, 2014;Barnhoorn et al, 2015). High levels of nutrients in aquatic ecosystems may influence the toxicity of insecticides, complicating the understanding of invertebrate community response (Alexander et al, 2013).…”

Section: Introduction -South Africa's Water Crisismentioning

confidence: 99%

Living with eutrophication in South Africa: a review of realities and challenges

Harding¹

2015

Transactions of the Royal Society of South Africa

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The socio-economic well-being of South Africa is largely dependent on reservoir lakes. Contrastingly, the country lacks reservoir management skills and training, with a generation having passed since there was limited activity in this field. This review introduces two new, independent analyses which, using in-lake total phosphorus or satellite-measured chlorophyll-a, respectively, reveal that between 41% and 76% of total storage is eutrophic or hypertrophic. This is in stark contrast to a claimed 5% made by the responsible government agency (Department of Water and Sanitation). Data and information on the incidence and toxicity of cyanobacterial blooms are sparse, yet severe problems exist. There is a concentration of focus on water quantity, with absent parallel consideration of the additional limitations posed by poor water quality. The most seriously impacted reservoirs are located in the economic heartland of South Africa, which has an extant regional water quality crisis. The reasons behind the startling lack of attention to reservoir limnology, despite clear and long-standing warnings, are examined and placed in the perspective of an acknowledged and impending water crisis. It will take considerable time to up-skill South African limnologists to meet the needs highlighted by worsening reservoir water quality, and to offset the social and economic impacts that will transpire, if not timeously ameliorated. The responsible agency urgently needs to establish a reservoir-management programme that embraces remaining individual and institutional memory, integrates all available relevant knowledge and scientific findings, prioritises needs and acquires those skills and resources necessary to meet what is likely to become a crippling legacy of inaction.

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An overview of cyanobacterial research and management in South Africa post-2000

Cited by 18 publications

References 18 publications

Quantitative Variations of Intracellular Microcystin-LR, -RR and -YR in Samples Collected from Four Locations in Hartbeespoort Dam in North West Province (South Africa) During the 2010/2011 Summer Season

Quantitative Variations of Intracellular Microcystin-LR, -RR and -YR in Samples Collected from Four Locations in Hartbeespoort Dam in North West Province (South Africa) During the 2010/2011 Summer Season

Food-web structure in the hypertrophic Rietvlei Dam based on stable isotope analysis: Specific and general implications for reservoir biomanipulation

Living with eutrophication in South Africa: a review of realities and challenges

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