三峡水库浮游植物初级生产力的季节变化与空间分布

研究在三峡库区选取秭归、巫山、云阳、忠县、木洞5 个断面, 自2012 年8 月至2013 年4 月采用黑白瓶法进行为期一周年季节性的原位初级生产力测定, 探讨初级生产力的季节变化、水平分布、垂直分布等动态特征。结果表明: 初级生产力平均值(以溶氧计)的四季变化规律为: 夏季5.613 mgO2/(Ld)春季3.630 mgO2/(Ld)冬季0.906 mgO2/(Ld)秋季0.552 mgO2/(Ld), 与浮游植物叶绿素a 含量的季节变化一致;在初级生产力的空间分布上, 5 个断面中库首最高(秭归)、库中次之(巫山、云阳、忠县)、库尾最低(木洞);且全年所有断面干流初级生产力均显著低于支流初级生产力;在垂直分布上, 初级生产力的最大值主要出现在水下0-1 m 间, 在水下1-5 m 随着水深增加呈现递减趋势, 光能可得性可能是限制浮游植物初级生产力的重要因子。相关性分析表明, 毛初级生产力与叶绿素a、溶解氧、pH 呈显著正相关。  

THE SEASONAL VARIATIONS AND SPATIAL DISTRIBUTION OF THE PRIMARY PRODUCTIVITIES OF PHYTOPLANKTON IN THE THREE GORGES RESERVOIR

In this study, we carried out the field sampling from August 2012 to April 2013 in order to analyze the seasonal variation and spatial distribution of the primary productivity (PP) of phytoplankton in the Three Gorges Reservoir (TGR). Five regions along the longitudinal axis of the TGR (i.e. Zigui, Wushan, Yunyang, Zhongxian, and Mudong) were selected for the measurements of PP with the white and black bottles method. The seasonal average values of PP (according to the dissolved oxygen) followed the order: summer 5.613 mgO2/(Ld) spring 3.630 mgO2/(Ld) winter 0.906 mgO2/(Ld) autumn 0.552 mgO2/(Ld). Light was an important limiting factor in the vertical distribution of PP. The maximum values were obtained between 0 m and 1 m underwater, and the PP decreased along with the increase in the depth from 1 m to 5 m. As for the horizontal distribution, the primary productivity was higher in the head region of the TGR, and the highest was in Zigui, followed by the middle region and the tail region. Moreover, the PP values were higher in the tributaries than in the mainstream. The gross primary productivity was highly correlated with chlorophyll-a, dissolved oxygen, and pH.