太湖夏季浮游细菌群落多样性的空间格局

THE SPATIAL PATTERN OF BACTERIOPLANKTON COMMUNITY COMPOSITION IN LAKE TAIHU IN SUMMER

为了研究太湖夏季浮游细菌群落多样性与水体营养盐的关系,在太湖全湖范围内开展了一次大规模浮游细菌采样调查,分析了太湖不同湖区浮游细菌丰度和多样性组成。研究发现,浮游细菌丰度在不同湖区中存在明显的空间差异,从北部和西部湖区沿湖流向东南方向至湖心和南部沿岸再到东部湖区呈下降趋势,这与太湖水体营养水平从高到低变化趋势一致。浮游细菌丰度与营养盐浓度回归分析结果显示,总磷(TP)与细菌丰度存在较好的正相关(R2=0.6392,n=29,P<0.01),而总氮(TN)与细菌丰度无显著相关(R2=0.0663,n=29,P>0.05)。因此,磷是太湖夏季浮游细菌生长的限制因子。不同湖区营养盐与浮游细菌群落多样性也具有显著的正相关,随着营养水平的升高,浮游细菌多样性增加。此外,细菌群落的组成在不同湖区间亦具有明显的空间异质性,与不同湖区营养水平空间变化一致。研究结果将有助于人们更好地理解淡水湖泊中微生物循环和生态系统功能。

The present study was designed to determine the spatial pattern of bacterioplankton community composition （BCC） in Lake Taihu in summer and to evaluate the relationship between trophic level and bacterial diversity. According to the survey conducted during August 2010, the bacterioplankton abundance significantly declined from the north and west of lake to the center and south, then to the east of the lake;and the changes were similar to the decline of the tro-phic levels in lake regions. In addition, Total phosphorus （TP） concentration but not total nitrogen （TN） was positively correlated with bacterioplankton abundance （R2=0.6392, n=29, P〈0.01;R2=0.0663, n=29, P〉0.05;respectively）. Thus, P is a limiting factor for the growth of bacterioplankton in summer in Lake Taihu. A positive correlation between trophic level and bacterioplankton diversity in different lake regions was also observed in present study. Moreover, distinct spa-tial heterogeneity of BCC was observed in summer in Lake Taihu, which is mainly in accordance with the changes in trophic levels in various lake regions. Our study may contribute to better understanding of microbial loop and their ecological function in freshwater lakes.