氮磷比对长江中下游地区浅水湖泊群浮游植物类群的影响

摘要

2003年夏和2004年夏对中国长江中下游地区的30个浅水湖泊的浮游植物类群进行调查。为了研究不同氮磷比(TN/TP)对浮游植物组成的影响，将浮游植物的六个门，分别在 TN/TP＞30、12＜TN/TP＜30、TN/TP＜12三个区间随总磷的变化规律进行研究。当 TN/TP从高水平(＞30)降到中等水平(12～30)时，除蓝藻门外的其他五个浮游植物门的斜率均随总磷的升高而增加。但是当 TN/TP从中等水平(12～30)降到低水平(＜12)时，除绿藻和隐藻门外，其他浮游植物门的斜率均随总磷的升高呈下降趋势。当 TN/TP从高水平(＞30)降到降至低水平(＜12)时，蓝藻门的斜率不断降低，说明蓝藻在较高 TN/TP有更好的生长潜力。同样发现，绿藻和隐藻门则随 TN/TP的降低有更好的生长潜力。当 TN/TP在高水平(＞30)和低水平(＜12)时，硅藻、甲藻和裸藻门的斜率均发生下降，说明这三个门的藻类在 TN/TP为中等水平(12～30)的环境中有更好的生长潜力。%The phytoplankton groups were investigated in 30 shallow Chinese lakes in the middle and lower reaches of the Yangtze River area in the summer of 2003 and 2004. To explore the effects of different nitrogen phosphorus ratios (TN/TP ratios) on the phytoplankton taxonomic composition of these study sites, six main taxonomic groups were studied with three TN/TP ratios intervals: TN/TP>30, 1230) to medium (12-30), the slopes of the total biomass curve increased, as did the relative abundances of all groups except Cyanophyta. But when the TN/TP declined from medium (12-30) to low (<12) levels, the slopes of most groups decreased except Chlorophyta and Cryptophyta. The amount of Cyanophyta increased with TP when TN/TP ratios declined from above 30 to below 12, suggesting that cyanobacteria adapted to higher TN/TP ratios. However, Chlorophyta and Cryptophyta tended to be restricted by phosphorus when TN/TP ratios declined from above 30 to below 12, and these groups adapted to lower TN/TP ratios. The biomass of Bacillariophyta, Pyrrophyta and Euglenophyta tended decreased when TN/TP ratios were above 30 and below 12, suggesting that medium TN/TP ratios (12-30) favoured these groups.