Ecological effects on enclosure culture demolition of Lake Hongze

Abstract

为研究湖泊网围养殖对湖泊生态系统的影响，2018年全年3次于洪泽湖养殖网围及主要出入湖河道开展调查，通过对比洪泽湖不同区域（河口、湖心、网围区、外围区和拆除区）水质及水生生物的空间分布特征，分析养殖网围拆除后湖泊生态系统的响应机制.结果表明，洪泽湖不同区域的水质及水生生物群落结构存在明显差异，其中养殖区水体总氮、总磷及悬浮颗粒物浓度明显低于河口和湖心，但浮游动植物密度及生物量则整体高于河口和湖心，且养殖区蓝藻、轮虫所占比重较高，这种分布差异很大程度上受外源输入及水动力条件影响.与之相对，养殖区内网围区、拆除区和外围区的水质及水生生物群落结构差异并不明显，表明养殖网围拆除后的短期时间内水质并未明显改善，且高藻类密度、低透明度的水体环境也不利于沉水植物的萌发生长与群丛恢复，有必要进一步采取合理有效的生态修复措施促进养殖迹地生态系统的恢复.;In order to investigate the ecological effects of enclosure culture on the lake ecosystem, the investigation was carried out three times in the enclosure culture of Lake Hongze and its inlets and outlets during 2018. The response mechanism of the lake ecosystem after enclosure culture demolition was analyzed based on the data accumulated by comparing the spatial distribution characteristics of water quality parameters, the phytoplankton, zooplankton, and benthos communities in different areas of Lake Hongze (estuary, lake center, enclosure area, peripheral area, and demolition area). The results show that there are obvious differences between water quality and aquatic organisms in different lake regions. The concentrations of total nitrogen, total phosphorus, and suspended particulate matter in the samples collected within the culture areas are slightly higher than samples collected in the estuary and lake center, but both density and biomass of the phytoplankton are lower in the culture areas than those in the estuary and lake center. The proportion of Cyanophyta and rotifers in the culture areas is higher than that in the estuary and lake center. This distribution difference is largely affected by external input and hydrodynamic conditions. On the contrary, the differences in water quality and aquatic organisms between various areas of the enclosure culture are not considerable, indicating that the water quality has not improved significantly in the short period after the enclosure culture is removed. And the water quality with high algae density and low transparency will be detrimental to submerged plant growth and community recovery. Therefore, it's necessary to take further rational and effective ecological restoration measures to promote the restoration of the enclosure culture ecosystems.