Roegner Amber F, Corman Jessica R, Sitoki Lewis M, Kwena Zachary A, Ogari Zachary, Miruka Jared Babu, Xiong Ame, Weirich Chelsea, Aura Christopher Mulanda, Miller Todd Rex
Joseph J. Zilber School of Public Health, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin, USA.
University of Oregon, Center for Global Health, Lincoln, Nebraska, USA.
Ecol Soc. 2023 Mar;28(1). doi: 10.5751/es-13860-280149.
Lake Victoria, bordered by Kenya, Tanzania, and Uganda, provides one of the largest freshwater fisheries in the world and supports millions in small-scale fishing communities. Historical environmental change, including population growth, nutrient loading, introduced invasive species, and rising temperatures, has resulted in eutrophication and persistent cyanobacterial harmful algae blooms (cyanoHABs) over recent decades, particularly in the shallower gulfs, bays, and inlets. CyanoHABs impact fisheries and food web dynamics and compromise food and water security for nearshore fisher populations. In this study, we examine the social-ecological impact of freshwater blooms on fisher health in one of these eutrophic regions, Winam Gulf in Lake Victoria. CyanoHABs persist for months and produce microcystins and hepatotoxins at levels unsafe for human health. We assessed potential risk and contribution of microcystin exposure through fish consumption, in addition to exposure through water source, and conducted 400 fisher and 400 household surveys. Average microcystin concentrations exceeded the World Health Organization (WHO) guideline for drinking water consistently during the long dry season, and cyanobacterial cell counts surpassed WHO standards for recreational risk in 84% of samples. Hazard quotients for fish consumed by young children were 5 to 10 times higher than permissible levels. In addition, fishers chronicled profound ecosystem changes with direct impact on livelihood, fisheries, and water quality with 77.4% reporting a decline in profit or catch, 83.1% reporting adverse impacts of cyanoHABs on fish in the lake, and 98.2% reporting indicators of declining water quality in the lake overall. Through the application of a social-ecological lens to a public health model, we identified spheres of influence that modify how fishers experience HABs related stressors and risks to provide a starting point at which to identify sustainable strategies to improve food and water security and livelihood for the millions in nearshore communities.
维多利亚湖与肯尼亚、坦桑尼亚和乌干达接壤，是世界上最大的淡水渔业产区之一，养活了数百万小规模渔业社区的居民。近几十年来，包括人口增长、养分负荷、外来入侵物种引入和气温上升在内的历史环境变化导致了富营养化以及持续的蓝藻有害藻华（cyanoHABs），特别是在较浅的海湾、港湾和河口。蓝藻有害藻华影响渔业和食物网动态，并危及近岸渔民群体的粮食和水安全。在本研究中，我们考察了淡水藻华对维多利亚湖维南湾这一富营养化地区渔民健康的社会生态影响。蓝藻有害藻华持续数月，产生的微囊藻毒素和肝毒素水平对人类健康不安全。我们评估了通过食用鱼类以及通过水源接触微囊藻毒素的潜在风险和贡献，并开展了400名渔民和400户家庭的调查。在漫长的旱季期间，微囊藻毒素平均浓度持续超过世界卫生组织（WHO）的饮用水指导标准，84%的样本中蓝藻细胞计数超过了WHO的娱乐风险标准。幼儿食用鱼类的危害商数比允许水平高5至10倍。此外，渔民记录了深刻的生态系统变化，这些变化对生计、渔业和水质产生了直接影响，77.4%的渔民报告利润或渔获量下降，83.1%的渔民报告蓝藻有害藻华对湖中的鱼类产生了不利影响，98.2%的渔民报告整个湖泊水质下降的指标。通过将社会生态视角应用于公共卫生模型，我们确定了一些影响范围，这些范围改变了渔民体验与有害藻华相关的压力源和风险的方式，从而提供了一个起点，以便确定可持续战略，改善近岸社区数百万人的粮食和水安全以及生计。
