大洋桥石藻Gephyrocapsa oceanica对海水酸化与营养盐胁迫的复合响应

Combined effects of seawater acidification and nitrogen deficiency on Gephyrocapsa oceanica

本文选取了大洋桥石藻(Gephyrocapsa oceanica)作为实验对象,通过CO_2加富实验模拟海水酸化环境,分析了氮充足和氮相对不足条件下海洋颗石藻对海水酸化的生理响应。结果发现在两种营养盐状态下,CO_2加富均能一定程度促进大洋桥石藻种群增长与Chl a浓度的增加。对比两种营养盐状态,氮相对不足条件下的大洋桥石藻细胞密度和叶绿素含量均有最显著的提高,表明低营养盐浓度和低的氮磷比可能更有利于大洋桥石藻的生长繁殖。电镜观测结果显示酸化对大洋桥石藻的钙化作用具有显著的负影响,并且在氮相对不足条件下,大洋桥石藻的细胞个体变小及比表面积升高。研究结果表明在未来寡营养的大洋上层水体,大气CO_2浓度升高会对大洋桥石藻的生理功能产生负面影响,但可能刺激大洋桥石藻的生长。

Combined influences of nutrients status and seawater CO2 concentration on microalgae growth and physiology of Gephyrocapsa oceanic was investigated.It was shown that the abundance of G.oceanic significantly increased during CO2 enrichment experiments at different nutrient levels（nitrogen-deficiency vs.nutrient-rich）.However,the strongest response was observed in cell density and chlorophyll aconcentration of G.oceanic when nitrogen was deficiency,suggesting low nutrients concentration and low N/P ratio might be favor to the cell growth.Besides,electron microscopy results indicated that seawater acidification had significant negative impact on the calcification and cell size distribution（became smaller）of G.oceanic when nitrogen was deficiency.However,in future oligotrophic open ocean,increasing CO2 concentration might stimulate G.oceanicthrive.