Taking Lake Gehu located in the Yangtze River Delta as the research object, the phytoplankton community and environmental variables at 18 sampling sites in Lake Gehu were monitored and investigated during the dry season (March) and the wet season (July) of 2020. On this basis, the phytoplankton biological integrity index (P-IBI) was established during dry and wet periods, and the health of the lake water ecosystem was evaluated. The results showed that the P-IBI in dry and wet periods was consistent throughout Lake Gehu, and the overall water ecological health assessment results were “moderate”. To test the stability of the P-IBI, the relationships between the P-IBI, its constituent parameters and a single water quality environmental factor were analyzed through redundancy analysis (RDA). The results showed that total nitrogen, the hypermanganate index, chlorophyll a, dissolved oxygen, ammonia nitrogen, and transparency were highly correlated with the P-IBI system. Comparing the composition of the P-IBI during dry and wet periods and the relationships between the P-IBI system and water quality factors in the two hydrological periods, it was found that the parameters of the P-IBI system differed greatly between the dry and wet periods. The number of significantly related water quality factors in the dry period was greater than that in the wet period, and the two-axis characteristic values, the correlations between the P-IBI system and the water quality factors, and the cumulative percentage of the dry period were higher than those in the wet period. In conclusion, the P-IBI exhibits temporal variation between hydrological periods, and the stability of the P-IBI evaluation system during the dry season is significantly better than that during the wet season.

以位于长三角地区的葛湖为研究对象，在2020年旱季（3月）和雨季（7月）对葛湖18个采样点的浮游植物群落和环境变量进行监测调查。在此基础上，建立干湿期浮游植物生物完整性指数（P-IBI），评价湖水生态系统的健康状况。结果表明，葛湖全区干湿期P-IBI基本一致，总体水生态健康评价结果为“中等”。为了测试P-IBI的稳定性，通过冗余分析（RDA）分析了P-IBI、其组成参数和单一水质环境因素之间的关系。结果表明，总氮、一种、溶解氧、氨氮和透明度与 P-IBI 系统高度相关。比较干湿期P-IBI的组成以及两个水文时期P-IBI系统与水质因子的关系，发现干、湿期P-IBI系统参数差异较大。潮湿的时期。枯水期显着相关水质因子数大于丰水期，两轴特征值、P-IBI系统与水质因子的相关性、枯水期累积百分比期均高于丰水期。总之，P-IBI 表现出水文时期之间的时间变化，