基于水质浮标在线监测的米氏凯伦藻赤潮过程及环境因子变化特征分析

相较于船舶走航监测, 海洋水质浮标在线监测的优势在于能够获取目标海域长期、连续监测数据, 能更好地反映环境状况的动态变化。为了厘清米氏凯伦藻赤潮的发生、发展动态, 本文以2017年6月南麂附近海域米氏凯伦藻赤潮为例, 分析海洋水质浮标获取的连续监测数据, 探讨米氏凯伦藻赤潮过程叶绿素a和水环境因子动态变化特征及其与气象要素的关系。赤潮期间, 水温为22.8~26.0℃、盐度为28.8‰~31.8‰、气温为20.4~27.3℃, 该温盐范围均适宜米氏凯伦藻的细胞生长; 较高的光照强度能够支持较高的藻类细胞密度。Pearson相关性分析显示, 米氏凯伦藻细胞密度与叶绿素a浓度呈显著正相关; 溶解氧(DO)及其饱和度(DO%)、pH、水温、气温等环境因子与叶绿素a浓度呈极显著正相关, 盐度与叶绿素a浓度呈极显著负相关。向岸风生海流有利于藻种向近岸较高营养区域汇集, 为赤潮的爆发创造有利条件。赤潮过程中, 叶绿素a浓度、溶解氧饱和度、pH发生了协同变化, 据此特征可以开展赤潮短期预警。

Variation characteristics of the evolution of Karenia mikimotoi bloom and environmental factors based on online monitoring buoy data*

Superior to traditional monitoring methods, the marine monitoring buoys are able to obtain long-term and real-time continuous marine environmental data to reflect the dynamic changes in marine environmental conditions. In order to clarify the occurrence and development of the red tide of Karenia mikimotoi, and to carry out integrated monitoring and early warning of red tide disasters, we analyzed the evolution of Karenia mikimotoi bloom and environmental factors based on online monitoring buoy data obtained from the coastal area of Nanji Island of Zhejiang Province in June 2017. K. mikimotoi bloom occurs in the sea water with temperature and salinity ranging from 22.8℃ to 26.0℃ and from 28.8 to 31.8, and when the air temperature is between 20.4℃ and 27.3℃, which are suitable for the cell growth of K. mikimotoi. Higher light intensity can support higher K. mikimotoi cell density. Pearson correlation analysis shows that the cell density of K. mikimotoi is significantly positively correlated with chlorophyll a (chl-a). Dissolved oxygen (DO), dissolved oxygen saturation (DO%), pH, water temperature, and air temperature are all significantly positively correlated with chl-a. Salinity is significantly negatively correlated with chl-a. Wind blowing ocean current may facilitate the accumulation of algae to the shore, which creates suitable conditions for the outbreak of red tides. During the red tide, chl-a, DO% and pH have synergistic changes, which may carry out red tide early-warning signs based on the online monitoring buoy data.