三峡水库香溪河库湾冬季甲藻水华生消机理初探

2010年1—2月在香溪河库湾上、中、下游各选取1个监测点对水体环境因子及藻类进行监测,对水温、营养盐含量等进行分析,探讨香溪河库湾冬季甲藻水华的生消机理.结果表明:2010年冬季,香溪河库湾末端暴发了甲藻水华,持续44 d,优势藻种为拟多甲藻(Peridiniopsis sp.),最高细胞密度达到11.8×106L-1;适宜的水温、充足的营养盐以及良好的光照、弱分层水体是香溪河库湾冬季甲藻水华暴发的主要原因;ZmixZeu〔Zmix(混合层深度)与Zeu(真光层深度)之比〕在2～3之间时有利于甲藻生长;库湾中下游因水体掺混强烈而在冬季未暴发水华;后期水体分层状态的加强及ZmixZeu的减小是甲藻水华消失的主要原因.

Preliminary Studies on the Mechanism of Winter Dinoflagellate Bloom in Xiangxi Bay of the Three Gorges Reservoir

In order to investigate the mechanism of the winter dinoflagellate bloom in Xiangxi Bay of the Three Gorges Reservoir,field data of phytoplankton and the corresponding water environmental factors were collected from January to February,2010.The dinoflagellate bloom was observed at the end of Xiangxi Bay,and Peridiniopsis sp.was identified as the predominant species.The bloom lasted for 44 days,and the maximum cell density reached 11.8×106 L-1.Moderate water temperature,adequate nutrients,sufficient sunlight and weak thermal stratification were identified as the main factors causing the dinoflagellate bloom.The favorable ratio of mixing depth to euphotic depth(Zmix/Zeu) for the growth of dinoflagellates was from 2 to 3.Algal bloom was not observed at the middle and lower reaches of Xiangxi Bay,which was due to the strong vertical mixing.The fading of the dinoflagellate bloom mainly resulted from the development of thermal stratification and the decrease of Zmix/Zeu.