In order to clarify the relationship between the formation of Karenia mikimotoi bloom and environmental factors,and grasp the rules of its occurrence and development,the meteorological,hydrological and nutrient con-ditions of the formation of K.mikimotoi bloom during the late spring and early summer of 2012 in the Sansha Bay were analyzed.Combined with laboratory experiment,the correlation between the formation of K.mikimotoi bloom and the environmental factors were discussed in this study.The results show that K.mikimotoi bloom usu-ally occurs in the sea water with temperature and salinity ranging from 20.5—25.0℃and 26.0—32.3,and the suit-able temperature and salinity for K.mikimotoi are 22.0—25.0℃and 26.0—30.0,respectively.Pearson correlation analysis shows that the cell density of K.mikimotoi is positively correlated with chlorophyll a,inorganic phos-phorus and chemical oxygen demand,and negatively correlated with transparency and ammonia nitrogen;K.miki-motoi cell has a low demand for phosphate,and the formation of bloom may be mainly affected by ammonia nitro-gen in water.Based on field investigation and simulation results,comprehensive analysis shows that the stable hydrological and meteorological conditions,the inorganic nitrogen input during the early stage rainfall,as well as the lower light intensity due to continuous overcast and rainy conditions were the important conditions for the for-mation and maintenance of the red tide.%为了理清米氏凯伦藻赤潮形成与环境因素的关系,掌握其发生、发展规律,本文分析了2012年春末夏初三沙湾海域米氏凯伦藻赤潮期间的气象、水文和营养盐情况,并结合室内模拟培养实验,探讨了米氏凯伦藻赤潮形成与各环境因素的相关性.结果显示米氏凯伦藻赤潮通常发生在温度为20.5~25.0℃和盐度为24.3~32.3的海域,其细胞生长的最适温度和最适盐度分别为:22.0~25.0℃和26.0~30.0;Pearson相关性分析显示,米氏凯伦藻细胞密度与叶绿素a、无机磷、化学需氧量呈极显著正相关,与透明度、氨氮呈显著负相关;另外,米氏凯伦藻对磷酸盐的需求较低,其赤潮的形成可能主要受水体中氨氮的影响.基于现场调查和模拟实验结果,综合分析认为稳定的水文和气象条件、发生前期降雨输入的无机氮,以及由于持续阴雨导致的较低光照条件是此次米氏凯伦藻赤潮形成和维持的重要条件.
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