Harmful Algal Blooms Threaten the Health of Peri-Urban Fisher Communities: A Case Study in Kisumu Bay, Lake Victoria, Kenya

Roegner, Amber; Sitoki, Lewis; Weirich, Chelsea A.; Corman, Jessica R.; Owage, Dickson; Umami, Moses; Odada, Ephraim; Miruka, Jared; Ogari, Zachary; Smith, Woutrina A.; Rejmánková, Eliška; Miller, Todd R.

doi:10.1007/s12403-019-00342-8

Cited by 35 publications

(25 citation statements)

References 56 publications

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“…However, due to the high recorded MC concentrations and the potentially high exposure of humans to these toxins (in comparison to populations from developed countries), these impacts on human health should be seriously considered. This hypothesis is supported by the recent paper ofRoegner et al (2020) showing that the health of peri-urban fisher communities in the area of Kisumu is threatened by the consumption and use of lake water contaminated with MCs and other HAB components. Moreover, in addition to the disturbances caused by cyanobacteria during the production of drinking water, human populations can also consume nontreated water from the lake or poorly treated water with potential exposure to fecal pathogens associated with waterborne diseases.…”

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confidence: 56%

“…Due to the demographic growth and the rising concentration of the population into urban areas in Africa (United Nation, 2018), we may fear that in the next decades, eutrophication of freshwater ecosystems and associated cyanobacterial blooms will continue to increase in LV and also in many other African lakes. Knowing that all these lakes provide numerous ecosystem G&S and are vital for the water and food supply, the high microcystin concentrations recorded in water and fishes of LV and the data of Roegner et al (2020) suggest that cyanobacteria and their toxins constitute a serious health concern for local populations. The same is probably true in many countries of the intertropical area in Africa.…”

Section: Resultsmentioning

confidence: 99%

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A review of the socioecological causes and consequences of cyanobacterial blooms in Lake Victoria

et al. 2020

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Africa is experiencing high annual population growth in its major river basins. This growth has resulted in significant land use change and pollution pressure on the freshwater ecosystems. Among them, the Lake Victoria basin, with more than 42 million people, is a unique and vital resource that provides food and drinking water in East Africa. However, Lake Victoria (LV) experienced a progressive eutrophication and substantial changes in the fish community leading to recurrent proliferation of water hyacinth and cyanobacteria. Based on an extensive literature review, we show that cyanobacterial biomasses and microcystin concentrations are higher in the bays and gulfs (B&Gs) than in the open lake (OL), with Microcystis and Dolichospermum as the dominant genera. These differences between the B&Gs and the OL are due to differences in their hydrological conditions and in the origins, type and quantities of nutrients. Using data from the literature, in this paper we describe the multiple ways in which the human population growth in the LV watershed is connected to the increasing occurrence of cyanobacterial blooms in the OL and B&Gs. We also described the already documented consequences of cyanobacterial blooms on food resources and fishing and on direct water use and water supply of local populations, with their potential consequences on the human health. Finally, we discuss the actions that have been taken for the protection of LV. Although many projects have been implemented in the 15 past years in order to improve the management of waste waters or to reduce deforestation and erosion, the huge challenge of the reduction of cyanobacterial blooms in LV by the control of eutrophication seems far from being achieved.

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confidence: 56%

Section: Resultsmentioning

confidence: 99%

A review of the socioecological causes and consequences of cyanobacterial blooms in Lake Victoria

et al. 2020

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“…The primary threat to humans is via direct exposure to toxigenic cyanobacteria and cyanotoxins through drinking water [4], mainly from contaminated untreated or treated water [31]. In our study the two WTPs efficiently purified raw water containing toxic cyanobacteria.…”

Section: Multiple Exposure Routes To Toxigenic Cyanobacteria and Cyan...mentioning

confidence: 99%

“…Aside from physiological effects, all these drivers are triggers of growth of the toxigenic cyanobacteria, Microcystis and Dolichospermum, and thus also influence the production of MC through cell division [30]. Earlier studies by Roegner et al [31] did not report potential predictors of MC presence or an increased MC concentration in another embayment, Kisumu Bay, Lake Victoria (Kenya). During our study period, the variation in MC concentration was associated with the biovolume of Microcystis spp.…”

Section: Factors Explaining MC Concentrationsmentioning

confidence: 99%

“…In general WTPs are susceptible to cyanotoxin contamination but data on cyanotoxin occurrence in treated water produced in the tropics is scanty [4,39]. Earlier studies in Lake Victoria focused on intracellular toxins [8,31] but less considered the risks of extracellular toxins. This study monitored both intra-and extracellular MC occurring through a conventional water treatment installed at the two embayments susceptible to cyanobacterial blooms.…”

Section: The Fate Of MC During Water Treatmentmentioning

confidence: 99%

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Characterization of Potential Threats from Cyanobacterial Toxins in Lake Victoria Embayments and During Water Treatment

Olokotum¹,

Humbert²,

Quiblier³

et al. 2022

Preprint

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Africa’s water needs are often supported by eutrophic waterbodies dominated by cyanobacteria posing health threats to riparian populations from cyanotoxins, and Lake Victoria is no exception. In two embayments of the lake (Murchison Bay and Napoleon Gulf), cyanobacterial surveys were conducted to characterize the dynamics of cyanotoxins in lake water and water treatment plants. Forty-six cyanobacterial taxa were recorded and out of these 14 were considered potentially toxigenic (i.e., from the genera Dolichospermum, Microcystis, Oscillatoria, Pseudanabaena and Raphidiopsis). A higher concentration (ranging from 5-10 µg MC-LR equiv. L-1) of microcystins (MCs) was detected in Murchison Bay compared to Napoleon Gulf, with a declining gradient from the inshore (max. 15 µg MC-LR equiv. L-1) to the open lake. In Murchison Bay, an increase either in Microcystis sp. biovolume and MC was observed over the last two decades. Despite high cell densities of toxigenic Microcystis and high MC concentrations, the water treatment plant in Murchison Bay efficiently removed the cyanobacterial biomass, intracellular and dissolved MC to below the lifetime guideline value for exposure via drinking water (&lt; 1.0 µg MC-LR equiv. L-1). Thus, the potential health threats stem from the consumption of untreated water and recreational activities, along the shores of the lake embayments. MC concentrations were predicted from Microcystis cell numbers regulated by environmental factors such as solar radiation, wind speed in the N-S direction and turbidity. Thus, an early warning through microscopical counting of Microcystis cell numbers is proposed to better manage health risks from toxigenic cyanobacteria in Lake Victoria.

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Understanding and predicting harmful algal blooms in a changing climate: A trait‐based framework

Litchman

2022

Limnol Oceanogr Letters

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Harmful algal blooms (HABs) in both freshwater and marine systems present a significant problem for water quality and ecosystem services and may be increasing globally. Our ability to understand and predict HABs in diverse aquatic ecosystems is still limited. Trait-based approaches where the focus is on functional traits provide a mechanistic framework to better understand the environmental drivers of HABs. Characterizing trait differences between HAB-forming and other taxa, as well as across and within different HAB-forming species will help elucidate their ecological niches and adaptive potential under different conditions. Trait-based models should enable better HAB predictions at different temporal and spatial scales.

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Harmful Algal Blooms Threaten the Health of Peri-Urban Fisher Communities: A Case Study in Kisumu Bay, Lake Victoria, Kenya

Cited by 35 publications

References 56 publications

A review of the socioecological causes and consequences of cyanobacterial blooms in Lake Victoria

A review of the socioecological causes and consequences of cyanobacterial blooms in Lake Victoria

Characterization of Potential Threats from Cyanobacterial Toxins in Lake Victoria Embayments and During Water Treatment

Understanding and predicting harmful algal blooms in a changing climate: A trait‐based framework

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