鄱阳湖河湖转换期间鱼腥藻(Anabaena)的变化

Variations of Anabaena in the transition levels between river- and lake-type of Lake Poyang

鄱阳湖作为我国长江目前仅存的两个通江湖泊之一,年内水位变幅巨大.通过在鄱阳湖2013年河湖转换期间（5—11月）对鄱阳湖主航道都昌段进行每月3~4次的高频监测,以考察鄱阳湖水体中鱼腥藻（Anabaena）的动态变化,分析鄱阳湖中鱼腥藻生长并占优势的影响因素.结果表明,蓝藻为鄱阳湖浮游植物的次级优势种,8月蓝藻生物量平均占浮游植物生物量的57%,蓝藻取代硅藻成为暂时的优势种.夏、秋季水华蓝藻以固氮鱼腥藻为主,主要与夏、秋季水温较高以及适宜的营养盐条件等有关.研究期间鄱阳湖水体氮磷比平均在15左右,鱼腥藻能够产生有固氮能力的异形胞,并在水华蓝藻中成为优势种,也反映了鄱阳湖某些湖区存在氮相对缺乏的阶段.

Lake Poyang is one of the two lakes naturally connecting with Yangtze River, with a dramatic and regular water level fluctuation every year. Data of the weekly monitoring from May to November in 2013 was used to study the variations of Anabaena and its heterocyst and the influence factors. It was showed that Cyanophyta was a subdominant species in Lake Poyang. Cyanophyta biomass was accounted for about 57% of total phytoplankton biomass, and Cyanophyta temporarily became the dominant species re- placing diatoms in August. The dominant species of Cyanophyta were nitrogen-fixing Anabaena due to the high water temperature and suitable nutrient in summer and autumn. The nitrogen and phosphorus ratios were around 15 in the study period. Anabaena pro- duced heterocyst and became the dominant species of Cyanophyta, reflecting relatively nitrogen deficiency in Lake Poyang. The re- suits can provide a theoretical basis for the protection and utilization of Lake Poyang.