固城湖生物资源现状及近20年间的变化趋势

1999年对固城湖渔业生物资源进行了周年调查,结合1981年4月至1982年3月、1987年6月至1988年5月的2次调查资料,比较分析了固城湖生物资源的动态。研究结果表明,从1981年至1999年近20a间,固城湖浮游植物数量增加44.8倍,生物量增加40.6倍,生物多样性减少。浮游动物数量较20世纪80年代下降约50%,生物量高于80年代初期,低于80年代后期。底栖动物生物量下降,其中瓣鳃类、腹足类生物量下降明显,而寡毛类和摇蚊幼虫等数量与生物量增长显著。固城湖水生植物演替剧烈,水生植物群落结构发生了重大变化,已由苦草、轮叶黑藻群落演变为微齿眼子菜、菹草群落,渔业利用价值下降。每年大量水草腐烂沉积,使固城湖水质呈现不断下降趋势。指出加强对固城湖生物资源的调控和综合利用,是固城湖生态保护和建设的关键。

Status quo and the succession of the biological resources in Lake Gucheng

Based on the survey of the biological resources in Lake Gucheng in 1999 and the survey data in 1981 and 1988,comparison was conducted to analyze dynamics of biological resources in the lake.It was found that within almost 20 years from 1981 to 1999 the population of phytoplanktons increased by 44.8 times in abundance and the biomass by 40.6 times,but the biodiversity reduced.The population of zooplanktons decreased by 50% as compared with that in the 1980s,while the biomass was higher than that in the early 1980s but lower than that in the late 1980s.The biomass of zoobenthos decreased,especially lamellibranch and mollusca,while that of freshwater oligochaeta and chironomidae larvae increased remarkably.The succession of hydrophyte community in Lake Gucheng was drastic and its structure changed greatly with Potamogoton maackianus and Potamogeton crispus communities replacing Vallisneria and Hydrilla verticillata communities,thus resulting in the fall of its fishery value.Every year large volumes of float grasses rotted and accumulated in the bottom,deteriorating the water quality of the lake.There are some indicator species that are contamination-tolerant,for instance,Bellamya purificata (heude),Parafossarulus striatulus (benson),Branchiura sowerbyi (beddard) and so on.The water quality showed a declining trend in the recent 20 years.The key to protection of the lake environment is to intensify regulation and to reasonably exploit the biological resources of the lake.