This study was carried out in order to investigate the spatial variation of algal toxin (microcystin) concentrations along the shoreline of Lake Victoria. A total of 16 nearshore stations differing in connectivity to the main lake basin were categorized as either closed bays (ratio of bay area to bay opening <1) or open bays (ratio ≥1) and sampled during November and December 2009. Water samples were analyzed for total phosphorus, chlorophyll a, phytoplankton community composition and concentrations of microcystin. Open and closed bays were significantly different for phytoplankton abundance and composition: Average phytoplankton biovolume was higher for closed bays (45 mm3l−1 ± 11 SE) than open bays (5 ± 2 mm3l−1). Cyanobacterial biovolume (mainly Microcystis spp., Anabaena spp. and Planktolyngbya spp.) was also significantly higher in closed bays (82 ± 9% of total biovolume) than in open bays (44 ± 5%). In contrast, diatom biovolume was lower in closed bays (7 ± 1%) than in open bays (36 ± 6%). Microcystins were found only among sites from closed bays and concentrations ranged from 0.4 to 13 µg l−1 Microcystin-LR equivalent and coincided with high abundance of Microcystis spp. It is concluded that the level of water exchange from individual bays to the main basin is an important factor influencing eutrophication and microcystin production in nearshore habitats of Lake Victoria.

中文翻译：

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坦桑尼亚维多利亚湖开放和封闭海湾的浮游植物组成和微囊藻毒素浓度

进行这项研究是为了调查维多利亚湖沿岸藻类毒素（微囊藻毒素）浓度的空间变化。在 2009 年 11 月和 2009 年 12 月期间，共有 16 个与主要湖盆连通性不同的近岸站点被归类为封闭海湾（海湾面积与海湾开口的比率 <1）或开放海湾（比率≥1）。分析总磷、叶绿素 a、浮游植物群落组成和微囊藻毒素浓度。开放海湾和封闭海湾的浮游植物丰度和组成存在显着差异：封闭海湾的平均浮游植物生物量（45 mm3l-1 ± 11 SE）高于开放海湾（5 ± 2 mm3l-1）。蓝藻生物量（主要是 Microcystis spp.、Anabaena spp. 和 Planktolyngbya spp. ) 也显着高于封闭海湾（总生物量的 82 ± 9%）比开放海湾（44 ± 5%）。相比之下，封闭海湾中的硅藻生物量 (7 ± 1%) 低于开放海湾 (36 ± 6%)。仅在封闭海湾的地点发现微囊藻毒素，浓度范围为 0.4 至 13 µg l-1 微囊藻毒素-LR 等效物，并且与微囊藻属的高丰度相吻合。得出的结论是，从单个海湾到主流域的水交换水平是影响维多利亚湖近岸栖息地富营养化和微囊藻毒素生产的重要因素。4 到 13 µg l-1 微囊藻毒素-LR 等效物，与高丰度的微囊藻属植物相吻合。得出的结论是，从单个海湾到主流域的水交换水平是影响维多利亚湖近岸栖息地富营养化和微囊藻毒素生产的重要因素。4 到 13 µg l-1 微囊藻毒素-LR 等效物，与高丰度的微囊藻属植物相吻合。得出的结论是，从单个海湾到主流域的水交换水平是影响维多利亚湖近岸栖息地富营养化和微囊藻毒素生产的重要因素。