洪泽湖有毒和无毒微囊藻丰度及其与环境因子之间的相关分析

Abundance of Toxic and Non-toxic Microcystis sp. in Lake Hongze and Its Correlation with Environmental Factors

为了解洪泽湖有毒和无毒微囊藻丰度及其空间分布,于2014年8月对洪泽湖30个采样点水体的营养盐浓度和Calson富营养化指数（trophic state index,TSI）进行研究,同时采用实时荧光定量PCR技术测定了有毒和无毒微囊藻丰度.结果表明,洪泽湖水体的总氮和总磷浓度平均值分别为1.63 mg·L-1和0.11 mg·L-1,富营养化指数在58.1-73.6之间,洪泽湖水质呈富营养化状态;有毒微囊藻在洪泽湖广泛分布,其丰度在1.13×104-3.51×106copies·m L-1之间,总微囊藻丰度在1.06×105-1.10×107copies·m L-1之间,有毒微囊藻占总微囊藻的比例在8.5%-38.5%之间,平均值为23.6%,有毒微囊藻丰度及其比例均呈现出明显的空间差异性;相关分析结果显示,总微囊藻、有毒微囊藻和有毒微囊藻所占比例三者之间呈极显著正相关性（P〈0.01）,总微囊藻和有毒微囊藻丰度与叶绿素a浓度和TSI有极显著正相关性（P〈0.01）,与透明度有极显著负相关性（P〈0.01）,有毒微囊藻所占比例与叶绿素a、总氮、总磷和TSI有极显著正相关性（P〈0.01）,与TN/TP和透明度有极显著负相关（P〈0.01）.因此,削减洪泽湖总氮、总磷浓度一方面可以降低水体富营养化水平,另一方面有利于抑制有毒微囊藻对无毒微囊藻的竞争优势.

In the present study,the eutrophic level of 30 water samples collected from Lake hongze in August 2014 were analyzed,and the abundance of toxic and non-toxic Microcystis sp.,together with their spatial distribution,was investigated by quantitative real-time PCR techniques. The results showed that the average concentrations of total nitrogen and total phosphorus were 1. 63 and 0. 11mg·L- 1,respectively. The trophic state index（ TSI） ranged from 58. 1 to 73. 6,and the water quality was in the state of eutrophication based on TSI. Toxic Microcystis was widely distributed in Lake Hongze,and its abundance varied sharply,from 1. 13 ×104to 3. 51 × 106copies·m L- 1,and the abundance of total Microcystis ranged from 1. 06 × 105 to 1. 10 × 107copies·m L- 1,meanwhile,the proportion of toxic Microcystis in the total Microcystis ranged from 8. 5% to 38. 5%,with the average value of 23. 6%. Correlation analysis indicated that there was a significant positive correlation among total Microcystis,toxic Microcystis and the toxic proportion（ P 0. 01）. The abundance of total and toxic Microcystis was significantly positively correlated to chlorophyll a（ Chl-a） concentrations and TSI（ P 0. 01）,but was negatively correlated to transparency（ SD）（ P 0. 01）. The ratio of toxic Microcystis to total Microcystis was significantly positively correlated to Chl-a,TN,TP and TSI（ P 0. 01）,but significantly negatively correlated to the ratio of TN to TP and SD（ P 0. 01）. Therefore,reducing total nitrogen and phosphorus concentrations could not only lower the eutrophication level of Lake Hongze,but also inhibit the competition advantage of the toxic Microcystis over non-toxic Microcystis.