东湖通道工程对沿线水域水生植物的影响

东湖通道是武汉市在建的交通路网工程，穿越东湖风景区，其中约5 km 为湖底隧道。通过研究施工围堰对沿线水域水生植物的影响，可为湖泊管理提供应对措施。于2014年3月和5月通道工程施工期间，在其沿线的典型水域如封闭区域、半封闭区域、敞水湖湾、敞水迎风岸带和新形成的堤岸外共设置16个采样点，调查水生植物的种类、生物量和水质参数等。结果表明，水生植物群落结构受水温的影响，3月采样时平均水温为13．7℃，未发现挺水植物，采集到菹草（Potamogeton crispus）、穗花狐尾藻（Myriophyllum spicatum）和五刺金鱼藻（Ceratophyl-lum oryzetorum）3种沉水植物以及荇菜（Nymphoides peltatum）1种浮叶植物，可见少量的漂浮植物浮萍（Lemna mi-nor），其中沉水植物菹草为绝对优势种；5月的平均水温为24．8℃，除上述 3种沉水植物外，还采集到了苦草（Val-lisneria natans），但菹草的优势地位明显下降，另外采集到了荇菜和菱（Trapa bicornis）2种浮叶植物，荇菜的相对生物量和优势度最高，也可见少量的浮萍。在相对封闭的水域，因受风浪的影响较小，这些区域相对于迎风岸带具有较高的水生植物覆盖度和生物量，水体的营养盐浓度也相对较高，总氮（TN）和总磷（TP）浓度的高低与水生植物生物量多少的变化趋势一致。通道施工形成的新岸堤外，只有部分位点分布有水生植物，其原因可能是因为目前这些位点缺乏种源、水体较深、透明度低等。由于通道围堰施工增加了沿线的封闭水体，使得水生植被的覆盖度和生物量大幅度提高，通道施工对其沿线水生植物的影响是正面的；施工期间对水生植物没有产生不利影响，但在工程竣工后拆除围堰时，须防止悬浮物和机械扰动对现有植被的破坏。

Influence of the East Lake Channel Project on Macrophytes in Nearby Waters

During the construction of underwater tunnel in Donghu Lake, a study was carried out on the macrophytes community structure and total biomass along its line in March and May, 2014. The results showed that the macrophytes community structure was affected by the water temperature. The coverage and biomass of macrophytes were higher in the relatively closed areas than those growing in areas obviously influenced by wind wave. The high biomass was always accompanied with high nutrient concentration in water column. Macrophytes were seldom observed in the water area near the newly built embankments. This was probably because of lack seeds, deep water and low transparency in these areas. However, these embankments will be removed after the tunnel is completed. In summary, the construction of underwater tunnel had positive influence on macrophytes as it increased the relatively closed areas along the project line.