黄色的蓝藻水华

Cyanobacterial blooms in yellow

随着全球气候变化和水体富营养化,在过去几十年中蓝藻水华改变了全球的淡水生态系统.蓝藻因独有的藻蓝蛋白而大多呈现蓝绿色,因此其水华也常称为蓝绿藻水华.然而随着蓝藻水华关注度的不断提升,尤其是监测和研究的不断深入,经常在水体中发现蓝藻水华出现黄化的现象.例如,太湖出现的黄色蓝藻水华,冬春季以长孢藻属(Dolichospermum)水华为主,夏秋季以微囊藻属(Microcystis)水华为主.即使外观看起来是蓝绿色的蓝藻水华,但仔细观察形成蓝藻水华的群体颗粒,也有部分呈现黄色,反之亦然.实际上,鉴于色素组成的差异性,也许水体中就没有两个颜色完全一致的蓝藻群体颗粒.目前对于黄色的蓝藻水华及其形成机理,国内外鲜有报道和研究.光照和氮限制被认为是最有可能的原因.在关注蓝藻水华黄化的同时,更应该关注和研究这些颜色变化给蓝藻水华及水环境所带来的风险和挑战,尤其是对水生态管理工作的启发和意义.

Cyanobacteria can form large blooms that threaten the water quality of lakes.Global warming and eutrophication contribute to the worldwide increase in cyanobacterial blooms,which have changed freshwater ecosystems around the world in the past few decades.Cyanobacterial have been commonly referred to as"blue-green algae"due to phycocyanin,a protein unique to cyanobacteria.However,cyanobacterial blooms are not always blue-green.In fact,with the increasing attention of cyanobacterial blooms,especially the deepening of monitoring and research,cyanobacterial blooms were found to be able to present yellowish green,yellow and brown.For example,the yellow cyanobacterial blooms are dominated by Dolichospermum during the winter and spring,and Microcystis during the summer and autumn in Lake Taihu.Moreover,even if cyanobacterial blooms appear blue-green in the distance,some of the cyanobacterial aggregates that form the blooms are yellow on closer inspection,and vice versa.In fact,given the differences in pigment composition of cyanobacterial aggregates,there may be no two cyanobacterial aggregates with the same color.At present,there are few literatures on the yellow cyanobacterial blooms and its mechanism.Light and nitrogen limitation are considered to be the most likely causes.More important,more attention should be paid to the risks and challenges brought by the color change of cyanobacterial blooms and the water environment,especially the enlightenment and significance for water ecological management.