黄河口日本鳗草(Zostera japonica)在环境胁迫下的光合响应研究

本文针对黄河口日本鳗草面临的水体浊度变化造成的光限制及重金属污染等双重胁迫，综合野外监测和室内控制实验，分别研究了水体浊度、重金属Cu胁迫以及重金属Cu与浊度耦合胁迫下的日本鳗草光合响应特征。研究发现:浊度胁迫、浊度与低浓度重金属Cu耦合胁迫下，日本鳗草叶片叶绿素含量降低，光合色素的合成受到抑制；叶绿素a与叶绿素b的比值较高，这一结果表明，捕光色素复合体II含量低的同时，叶片通过减少对光能的捕获，降低了日本鳗草光合机构遭受破坏的风险；而在单一的浊度胁迫下，随着光化学猝灭系数下降，日本鳗草用于电子传递的能量逐渐减少，光能利用效率降低；随胁迫时间延长，日本鳗草最大光化学效率也出现下降；同样单一重金属Cu胁迫下，日本鳗草对Cu长期处理表现出抗性差，其光合作用也受到较大影响。据此推测，日本鳗草是对浊度胁迫有一定适应性的海草种类，但污染胁迫如重金属Cu对日本鳗草光合作用影响比水体浊度胁迫影响更大。 

Photosynthetic response of Zostera japonica during environmental stress in the Yellow River Estuary

Seagrass in the Yellow River Estuary has light limitation problems caused by water turbidity and Cu pollution. Effect of different combinations of light limitation (water turbidity and heavy metal contamination)on Zosterajaponica fluorescence properties was therefore investigated here by field monitoring and laboratory experiments, Turbidity stress and coupled stress of turbidity and low heavy metals Cu concentration was found to reduce chlorophyll content of Zostera japonica blade and inhibit photosynthetic pigment synthesis.Ratio of chlorophyll a/b under both scenarios was higher than under coupled stress of turbidity and high Cu concentration,showing the content of light harvesting complexes is lower in the former. Under environmental stress,qP value decreased,energy for electron transfer was reduced,reducing the light use efficiency.In short,Zostera japonica had stronger compatibility with turbidity stress and was not sensitive to different turbidity gradient stress.However,it was affected by duration of turbidity stress and stress scenarios.The effect of Cu on Zosterajaponica photosynthesis was greater than water suspended particles.