洪湖水体营养和沉水植被年际变化及生态恢复困境分析

Interannual Variations of Nutrients and Submerged Macrophytes in Honghu Lake and the Challenges of Ecological Restoration

摘要: 洪湖是我国第七大湖，湖北省第一大湖，曾有“湖北之肾”的美称，然而目前其水生态环境已严重恶化，大部分水域水质已沦为劣V类，全湖沉水植被几乎消亡。本文我们通过文献检索和数据整合，首先分析了洪湖水体营养指标，如水体总氮、总磷、氨氮和高锰酸钾指数在60多年(1959~2020年)的年际变化以及综合营养状态指数20多年(2000~2024年)的年际变化；然后，分析了自1960s以来洪湖沉水植被生物量的变化趋势以及1997~2021年间沉水植被物种数的变化。结果表明，洪湖水体营养逐年增加，水体营养状态从中营养已升至为中度富营养状态，水质也从较好的II~III类转变成如今的劣V类；而且随着水环境的变差，大型沉水植物分布面积也在逐渐缩减，单位面积生物量从近5000 g/m²断崖式下降到现在几乎为零，沉水植物物种数也从以前的20多种下跌到只剩2~3种。最后分析了目前洪湖沉水植被恢复的困难点并提出了针对性的、具有建设性的建议。该研究结果可为洪湖生态系统恢复和保护提供理论指导。

Abstract: Honghu Lake is the seventh largest lake in China and the largest in Hubei Province, once known as the “kidney of Hubei”. However, its water ecological environment has severely deteriorated, with most areas now classified as grade inferior V, and submerged vegetations in the entire lake has almost vanished. We conducted a literature review and data integration to first analyze the water nutrients of Hong Lake, such as total nitrogen, total phosphorus, ammonia nitrogen, and potassium permanganate index, over a period of more than 60 years (1959~2020), as well as the interannual variation of the comprehensive nutrient status index over more than 20 years (2000~2024). Then, we analyzed the trend of biomass changes in submerged vegetations since the 1960s and the changes in the number of submerged macrophyte species between 1997 and 2021. The results indicated that the water nutrients in Honghu Lake have been increasing year by year, with lake nutrient status shifting from mesotrophic to moderate eutrophic. Moreover, the water quality of Honghu Lake deteriorated from a relatively good grade II~III to the current grade inferior V. In addition, as the water environment worsens, the distribution area of large submerged plants is also gradually shrinking, with biomass per unit area plummeting from nearly 5000 g/m² to almost zero, and the number of submerged macrophyte species dropping from over 20 to only 2~3. Finally, we analyzed the current difficulties in restoring submerged vegetation in Honghu Lake and provided targeted and constructive suggestions. The findings of this study can provide theoretical guidance for the restoration and protection of the Honghu Lake ecosystem.