An overview of cyanobacterial bloom occurrences and research in Africa over the last decade

Ndlela, Luyanda L; Oberholster, Paul Johan; Wyk, J.H. van; Cheng, Po-Hsun

doi:10.1016/j.hal.2016.10.001

Cited by 124 publications

(76 citation statements)

References 85 publications

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“…For example, regarding spatial information, recent meta-analysis (Merel et al, 2013a) identified a disproportionality between well-covered regions including the USA, Canada, Europe and Australia, versus other (highly vulnerable) areas including much of South America, Asia or Africa , Merel et al, 2013a. However, a recent survey has col-N o n -c o m m e r c i a l u s e o n l y lated more information on activities in Africa (Ndlela et al, 2016). Further surveys in these continents are needed for truly global mapping of toxic cyanobacteria risks.…”

Section: Horizontal and Cross-cutting Issuesmentioning

confidence: 99%

Toxic cyanobacteria and cyanotoxins in European waters – recent progress achieved through the CYANOCOST Action and challenges for further research

et al. 2017

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This review aims to summarise the outcomes of some recent European research concerning toxic cyanobacteria and cyanotoxins, with an emphasis on developments within the framework of the CYANOCOST Action: COST Action ES1105, Cyanobacterial Blooms and Toxins in Water Resources: Occurrence, Impacts and Management. Highlights of the Action include phycological and ecological studies, development of advanced techniques for cyanotoxin analysis, elucidation of cyanotoxin modes of action, management techniques to reduce cyanobacterial mass development, and research on methods and practices for cyanotoxin removal during drinking water treatment. The authors have identified a number of gaps in knowledge. Proposed directions for future research on toxic cyanobacteria and cyanotoxins are also discussed.

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Section: Horizontal and Cross-cutting Issuesmentioning

confidence: 99%

Toxic cyanobacteria and cyanotoxins in European waters – recent progress achieved through the CYANOCOST Action and challenges for further research

et al. 2017

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“…In this sense, several studies have reported the abundance and dominance of Microcystis species in a wide range of freshwater sources (Carmichael, ; Harke et al, ), forming toxic blooms in tropical regions (e.g., Vieira et al, ; Soares et al, ; Ndelela, Oberholster, Wyk, & Cheng, ), subtropical areas (e.g., Kankaanpaa et al, ; O´Farrell & Bordet, ; Wu et al, ; Aguilera, Haakonsson, Martin, Salerno, & Echenique, ), and temperate zones (e.g., Tsukada, Tsujimura, & Nakahara, ; Mankiewicz‐Boczek et al, ; Harke et al, ). However, there are few reports studying the ecophysiological traits of Aphanocapsa species even in laboratories (e.g., Allen & Hutchison, ; Allen, Hutchison, & Weathers, ; Allen & Weathers, ; Domingos, Rubim, Molica, Azevedo, & Carmichael, ).…”

Section: Introductionmentioning

confidence: 99%

Environmental factors driving the dominance of the harmful bloom‐forming cyanobacteria Microcystis and Aphanocapsa in a tropical water supply reservoir

Magalhães

Luz

Junior

2019

Water Environment Research

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Harmful cyanobacterial blooms in reservoirs have become a serious global issue for environmental health. However, dominance among different toxic cyanobacteria genera remains poorly understood, especially in tropical areas. We evaluated the influence of environmental factors, including total phosphorus, dissolved aluminum, water level, and precipitation on the change of the dominant genus from Microcystis to Aphanocapsa, in a hypereutrophic tropical reservoir, using 443 water samples over six years of field monitoring by applying generalized linear models (GLM). The results pointed out the prevalence of longer hydrologic retention time leading to enhanced water stability, and nutrients' accumulation into the hypolimnetic zones of the reservoir may have favored the ecophysiological advantages for the picocyanobacteria Aphanocapsa, which reached densities greater than 1 million/ml. In addition, this article also suggests that physical-chemical remediation methods applied for immobilizing phosphorus in the sediments of the reservoir may be low effective in limiting cyanobacterial growth. These findings are not only meaningful to the understanding of the dynamics of cyanobacterial genera but also to improve the management of eutrophic reservoirs in tropical regions. © 2019 Water Environment Federation • Practitioner points• We assessed cyanobacterial dominance changes based on 6-year field monitoring.• First article addressing the dominance of Aphanocapsa spp. in a tropical reservoir.• Species of Aphanocapsa responded better to hydrological changes in the reservoir.• The use of remediators was accompanied by an increase in cyanobacteria biomass.

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“…In the last decades, MC occurrence has been investigated in some African countries, with MCs reported from Northern Africa (Algeria, Egypt, Morocco, Tunisia), Eastern Africa (Ethiopia, Kenya, Mozambique, Tanzania, Uganda), Southern Africa (Botswana, Lesotho, South Africa) (Mowe et al, 2014;Harke et al, 2016;Ndlela et al, 2016). However, available data about cyanotoxin contamination are still very scarce for most African countries and being nearly absent for regions such as West and Central Africa (Mowe et al, 2014;Harke et al, 2016;Ndlela et al, 2016).…”

Section: Introductionmentioning

confidence: 99%

“…However, available data about cyanotoxin contamination are still very scarce for most African countries and being nearly absent for regions such as West and Central Africa (Mowe et al, 2014;Harke et al, 2016;Ndlela et al, 2016). These are two large geographical areas with 26 countries and nearly half a billion inhabitants, where Central Africa is represented by nine countries populated by approximately 155 mil people, and West Tropical Africa by 17 countries with a combined population of about 344 mil people (UNSD, 2014).…”

Section: Introductionmentioning

confidence: 99%

Cyanobacteria and microcystin contamination in untreated and treated drinking water in Ghana

Addico¹,

Hardege²,

Kohoutek³

et al. 2017

Adv Ocean Limnol

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Although cyanobacterial blooms and cyanotoxins represent a worldwide-occurring phenomenon, there are large differences among different countries in cyanotoxin-related human health risk assessment, management practices and policies. While national standards, guideline values and detailed regulatory frameworks for effective management of cyanotoxin risks have been implemented in many industrialized countries, the extent of cyanobacteria occurrence and cyanotoxin contamination in certain geographical regions is underreported and not very well understood. Such regions include major parts of tropical West and Central Africa, a region constisting of more than 25 countries occupying an area of 12 million km 2 , with a total population of 500 milion people. Only few studies focusing on cyanotoxin occurrence in this region have been published so far, and reports dealing specifically with cyanotoxin contamination in drinking water are extremely scarce. In this study, we report seasonal data on cyanobacteria and microcystin (MC) contamination in drinking water reservoirs and adjacent treatment plants located in Ghana, West Africa. During January-June 2005, concentrations of MCs were monitored in four treatment plants supplying drinking water to major metropolitan areas in Ghana: the treatment plants Barekese and Owabi, which serve Kumasi Metropolitan Area, and the plants Kpong and Weija, providing water for Accra-Tema Metropolitan Area. HPLC analyses showed that 65% samples of raw water at the intake of the treatment plants contained intracellular MCs (maximal detected concentration was 8.73 µg L -1 ), whereas dissolved toxins were detected in 33% of the samples. Significant reduction of cyanobacterial cell counts and MC concentrations was achieved during the entire monitoring period by the applied conventional water treatment methods (alum flocculation, sedimentation, rapid sand filtration and chlorination), and MC concentration in the final treated water never exceeded 1 µg L -1 (WHO guideline limit for MC-LR in drinking water). However, cyanobacterial cells (93-3,055 cell mL -1 ) were frequently found in the final treated water and intracellular MCs were detected in 17% of the samples (maximal concentration 0.61 µg L -1 ), while dissolved MCs were present in 14% of the final treated water samples (maximal concentration 0.81 µg L -1 ). It indicates a borderline efficiency of the water treatment, thus MC concentrations in drinking water might exceed the WHO guideline limit if the treatment efficiency gets compromised. In addition, MC concentrations found in the raw water might represent significant human health risks for people living in areas with only a limited access to the treated or underground drinking water.

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An overview of cyanobacterial bloom occurrences and research in Africa over the last decade

Cited by 124 publications

References 85 publications

Toxic cyanobacteria and cyanotoxins in European waters – recent progress achieved through the CYANOCOST Action and challenges for further research

Toxic cyanobacteria and cyanotoxins in European waters – recent progress achieved through the CYANOCOST Action and challenges for further research

Environmental factors driving the dominance of the harmful bloom‐forming cyanobacteria Microcystis and Aphanocapsa in a tropical water supply reservoir

Cyanobacteria and microcystin contamination in untreated and treated drinking water in Ghana

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