Available guidance to mitigate health risks from exposure to freshwater harmful algal blooms (HABs) is largely derived from temperate ecosystems. Yet in tropical ecosystems, HABs can occur year-round, and resource-dependent populations face multiple routes of exposure to toxic components. Along Winam Gulf, Lake Victoria, Kenya, fisher communities rely on lake water contaminated with microcystins (MCs) from HABs. In these peri-urban communities near Kisumu, we tested hypotheses that MCs exceed exposure guidelines across seasons, and persistent HABs present a chronic risk to fisher communities through ingestion with minimal water treatment and frequent, direct contact. We tested source waters at eleven communities across dry and rainy seasons from September 2015 through May 2016. We measured MCs, other metabolites, physicochemical parameters, chlorophyll-a, phytoplankton abundance and diversity, and fecal indicators. We then selected four communities for interviews about water sources, usage, and treatment. Greater than 30% of source water samples exceeded WHO drinking water guidelines for MCs (1 µg/L), and over 60% of source water samples exceeded USEPA guidelines for children and immunocompromised individuals. 50% of households reported a sole source of raw lake water for drinking and household use, with alternate sources including rain and boreholes. Household chlorination was the most widespread treatment utilized. At this tropical, eutrophic lake, HABs pose a year-round health risk for fisher communities in resource -limited settings. Community-based solutions and site-specific guidance for Kisumu Bay and similarly impacted regions is needed to address a chronic health exposure likely to increase in severity and duration with global climate change.

减轻因暴露于淡水有害藻华 (HAB) 而带来的健康风险的现有指南主要来自温带生态系统。然而，在热带生态系统中，有害藻华可全年发生，依赖资源的人群面临多种接触有毒成分的途径。沿着肯尼亚维多利亚湖的 Winam 海湾，渔民社区依赖被来自 HAB 的微囊藻毒素 (MC) 污染的湖水。在基苏木附近的这些城郊社区，我们检验了以下假设：MCs 跨季节超过暴露指南，而持久性 HAB 通过摄入最少的水处理和频繁的直接接触对渔民社区构成慢性风险。我们在 2015 年 9 月至 2016 年 5 月的旱季和雨季对 11 个社区的源水进行了测试。我们测量了 MC、其他代谢物、理化参数、叶绿素-a、浮游植物丰度和多样性以及粪便指标。然后我们选择了四个社区进行关于水源、使用和处理的采访。超过 30% 的源水样本超过了世卫组织关于 MCs 的饮用水指南 (1 µg/L)，超过 60% 的源水样本超过了美国环保署针对儿童和免疫功能低下者的指南。50% 的家庭报告了饮用和家庭使用的原始湖水的唯一来源，其他来源包括雨水和钻孔。家庭氯化是使用最广泛的处理方法。在这个热带富营养化湖泊中，有害藻华对资源有限环境中的渔民社区构成全年的健康风险。