The impact of environmental variables and processes of nutrient enrichment on phytoplankton community at Epe lagoon was studied for 18 months (November 2012–April 2014). Two cyanobacterial bloom incidences were observed in the two dry seasons during this period. Rainfall pattern regulated nitrogen limitation which triggered cyanobacterial bloom development and influenced the bloom duration. Nutrient-laden influx from agricultural practices accounted for the increase in nitrate, phosphate and the relatively low silicate. Hypoxic conditions during the two bloom episodes reflected the vulnerability of this lagoon ecosystem. The cyanobacterial blooms were dominated by potentially toxic species; Anabaena circinalis, A. flos-aquae, A. limnetica and A. spiroides. A comparison of ambient nutrient ratios with the Redfield ratio (N/P/Si = 16:1:16) showed clear temporal variations that coincided with phytoplankton dynamics and the bloom regime. Low N/P ratios were recorded during the first 8 months, and there was a shift to higher ratios during the subsequent 8 months, followed by low N/P ratios in the last 2 months. Higher silicate values coincided with decreased cyanobacterial biomass, cyanobacteria bloom collapse and proliferation of diatoms during the first annual cycle. Cyanobacterial abundance exceeded the alert level 1 and almost reached alert level 2 which call for continuous environmental monitoring and management of coastal waters.

中文翻译：

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尼日利亚埃佩泻湖养分和浮游植物的动态：蓝藻水华重现的可能原因和后果

研究了环境变量和养分富集过程对埃佩泻湖浮游植物群落的影响，历时18个月（2012年11月至2014年4月）。在此期间的两个干旱季节，观察到两次蓝藻水华发生率。降雨模式调节了氮的限制，从而触发了蓝藻水华的发生并影响水华的持续时间。来自农业的大量养分流入导致硝酸盐，磷酸盐和相对较低的硅酸盐增加。两次开花期间的缺氧状况反映了该泻湖生态系统的脆弱性。蓝藻水华主要由潜在的有毒物种引起。鱼腥藻，A. flos - aquae，A。limnetica和A. spiroides。环境养分比与雷德菲尔德比（N / P / Si = 16：1：16）的比较显示出明显的时间变化，与浮游植物的动态变化和开花规律相吻合。在最初的8个月中记录到较低的N / P比率，在随后的8个月中出现了向较高比率的转变，随后在最近的2个月中出现了较低的N / P比率。较高的硅酸盐值与蓝细菌生物量减少，蓝细菌花期崩溃和硅藻在第一年周期内的增殖相吻合。蓝细菌的丰度超过了警报等级1，几乎达到了警报等级2，这要求对沿海水域进行连续的环境监测和管理。