赤潮异弯藻有色可溶性有机物的变化以及对其他微藻的影响

Changes of chromophoric dissolved organic matter in Heterosigma akashiwo (Hada) and its effects on other microalgae

赤潮消长显著影响海洋中有色可溶性有机物(CDOM)的变化。赤潮异弯藻(Heterosigma akashiwo)是一种常发的鱼毒性赤潮种类,是产生CDOM较显著的种类。本文以赤潮异弯藻CDOM为研究对象,分析了CDOM在种群消长中的变化特征,研究了光对赤潮异弯藻CDOM组成物质变化的影响,并就此变化对其他微藻种群生长造成的影响进行了定量研究。结果表明:(1)以紫外吸收的定量变化为指标,赤潮异弯藻CDOM的量与种群消长呈互逆相关:种群密度增加,CDOM降低;种群密度降低,CDOM增加;长期培养种群中,CDOM含量增加。(2)光对该藻产生的CDOM物质组成和定量有显著影响,紫外照射能显著漂白CDOM,类腐殖质和腐殖酸降解明显。(3)该藻CDOM变化影响其他微藻种群生长:CDOM显著促进微小卡罗藻(Karlodinium micrum)、小硅藻(Nitzschia closterium f.minutissima)的种群生长,受光降解后对小硅藻的促进作用降低,但对微小卡罗藻的促进作用不变;CDOM抑制海洋原甲藻(Prorocenturm micans)种群生长,光降解后,其抑制作用降低。赤潮异弯藻赤潮产生的大量且稳定的CDOM可以影响海洋微型生物群落结构。

The initiation and collapse of red tide will induce changes of chromophoric dissolved organic matter（CDOM）,which may potentially affect the community structure of marine organisms.Heterosigma akashiwo（Hada） is one of common red tide species,with ichthyotoxicities,and production of CDOM.In this study,the chemical characteristics of CDOM from H.akashiwo have been analyzed along with its population growth cycle,as well as the various light source treatments.The effects of CDOM on different microalgae have been also quantified.The results showed that（1） the production of CDOM is inversely correlated with the population growth,namely,increase of microalgal density accompanied by decrease of CDOM content,vice versa.The production of CDOM is continually increased in the maintenance of high density population.（2） The light irradiation affected content and composition of CDOM significantly,resulting in large degradation of humic substances by UV.（3） CDOM affected the growth of microalgae depending on the species.Stimulating effects were observed on Karlodinium micrum and Nitzschia closterium f.minutissima,and inhibitory effects on Prorocenturm micans.Such effects will be decreased for the CDOM after UV treatment.In conclusion,H.akashiwo,especially at large population,can affect the water qualities and phytoplankton community structures through the production of extracellular chromophoric dissolved organic matter.