中文摘要：

CO2浓度升高导致的海洋酸化会对大型海藻的生长、生理生态以及营养盐的吸收产生影响.本研究分析了3种pH条件下,3种大型海藻[孔石莼、萱藻、小珊瑚藻（钙化藻）]单养和混养的生长以及营养盐（磷酸盐PO34-和硝酸盐NO3-）的吸收利用情况.单养时,孔石莼、萱藻、小珊瑚藻的第10 d湿重增加百分比分别在pH 7.9、7.6、8.2条件下最多,并且小珊瑚藻在pH 7.6时的相对增长率显著低于在pH 8.2时的相对增长率.混养结果表明,低pH有利于萱藻生长,而高pH有利于小珊瑚藻生长.无论单养还是混养,3种pH条件下的培养液中PO34-、NO3-含量随时间延长而逐渐降低.在0～2 d培养液中PO34-含量急剧下降（降低了71.9%～99.0%）,随后PO34-含量下降缓慢.单养时,孔石莼、萱藻、小珊瑚藻分别在pH 8.2、8.2、7.6时的PO34-吸收速率最高;孔石莼、小珊瑚藻分别在pH 8.2、7.6时的NO3-吸收速率最高.混养时,孔石莼＋萱藻、孔石莼＋小珊瑚藻、萱藻＋小珊瑚藻分别在pH 7.6、8.2、8.2时的PO34-吸收速率最高;孔石莼＋小珊瑚藻在pH 7.6时的NO3-吸收速率最高.小珊瑚藻单养在pH 7.6时的低生长以及营养盐（PO34-和NO3-）的高吸收速率结果表明,PO34-和NO3-的吸收与同化作用并不相偶联.尽管两种藻混养中的优势种并未因海洋酸化而改变,但藻的种类组成比例发生了变化.因此,自然环境中海洋酸化对不同海藻的生长和营养盐吸收的长期影响可能会导致藻群落结构的改变.

英文摘要：

The ocean acidification caused by elevated CO2 concentration can affect the growth,physiology and ecology,and nutrient uptake of macroalgae.In this paper,the growth and nutrient（PO3-4 and NO-3） uptake of three species of macroalgae [Ulva pertusa,Scytosiphon lomentaria and Corallina pilulifera（calcified algae）] at three pHs（8.2,7.9 and 7.6） were investigated under conditions of monoculture and mixed culture.Under the condition of monoculture,the percents of increased wet weights of U.pertusa,S.lomentaria and C.pilulifera on day 10 were the highest at the pHs of 7.9,7.6 and 8.2,respectively,when compared with those on day 0,and the relative growth rates of C.pilulifera at pH 7.6 were significantly lower than those at pH 8.2.The data of mixed culture experiments suggested that lower pH was beneficial for the growth of S.lomentaria,while higher pH was beneficial for the growth of C.pilulifera.In both monoculture and mixed culture,the PO3-4 and NO-3 concentrations at the three pHs decreased with the time.The PO3-4 concentrations decreased sharply by 71.9%-99.0% from day 0 to day 2,and then decreased smoothly.Under the conditions of monoculture,the PO3-4 uptake rates of U.pertusa,S.lomentaria and C.pilulifera were the highest at pHs of 8.2,8.2 and 7.6,respectively.The NO-3 uptake rates of U.pertusa and C.pilulifera in monoculture were the highest at pHs of 8.2 and 7.6,respectively.Under the conditions of mixed culture,the PO3-4 uptake rates of U.pertusa ＋S.lomentaria,U.pertusa ＋ C.pilulifera,S.lomentaria＋C.pilulifera were the highest at pHs of 7.6,8.2 and 8.2,respectively.The NO-3 uptake rates of U.pertusa ＋ C.pilulifera at pH 7.6 were the highest among the three pHs.The lower growth and higher nutrient（PO3-4 and NO-3） uptake rates of monoculture C.pilulifera at pH 7.6 showed that the uptake and assimilation of PO3-4 and NO-3 were not coupled.The species composition of algae was changed due to ocean acidification although the dominant species was not change.Therefore,the different responses of g