摘要
自20世纪60年代以来,瑞典梅拉伦湖、哈马伦湖、韦特恩湖和维纳恩湖等大湖泊的浮游植物和环境变量一直处于监测之下。20世纪70年代政府出台了一些减少磷和工业废品排放的措施,于是水体磷的含量降低了90%～95%,结果大多数污染湖盆磷的浓度减少了一半。体现在浮游植物群落的变化是夏季蓝藻细菌、春季硅藻和隐鞭毛藻的生物量迅速降低,另一个反应是藻华期变短,生长季节的物种丰富度和生物量均匀度增加,浮游植物群落内物种数量和组成发生变化。此外,大湖泊物种丰富度相应与湖泊的特征有关。本文对湖泊中有毒蓝藻细菌的发生作了介绍,结合哈马伦湖和梅拉伦湖的藻华,确定在13～0.1μg/L之间的微藻素最大和最小值;给出利用浮游植物作为监测指标确定水质量变化的基本框架,并提出了评价标准。
Phytoplankton and environmental variables have been monitored in the large Swedish lakes Malaren, Hjalmaren, Vattern and Vanern since the 1960s. Measures to reduce phosphorus input and industrial waste products were taken during the 1970s. The phosphorus loading was then reduced by 90–95% resulting in a halving of the phosphorus concentrations in the most affected basins. The phytoplankton community reacted rapidly with decreased biomasses of cyanobacteria in summer as well as decreased biomasses of spring diatoms and cryptophycean flagellates. Other reactions were a contracted period of waterbloom, an increased taxon richness, an increased evenness in the biomass over the growth season, and a change in the species size structure within the phytoplankton community. Furthermore, the species richness in the large lakes is compared in relation to lake characteristics. A presentation of the occurrence of toxic cyanobacteria in the lakes is also given. Maximum–minimum values of 13–0.1 μg microcystin L^-1 are established in connection with waterblooms in Hjalmaren and Malaren. The use of phytoplankton as a monitoring variable to detect water-quality changes is outlined and assessment criteria are presented.
