漂浮型铜藻与养殖裙带菜的光合作用、生长和物质积累的差异及其在两种藻竞争中的作用

Differences in Photosynthesis,Growth and Resource Accumulation Between Drifting Alga Sargassum horneri and Cultured Alga Undaria pinnatifida and Their Roles in Interspecies Competition

近年来,由漂浮型铜藻(Sargassum horneri)频繁引发的金潮对东海、黄海沿岸的经济海藻养殖造成了巨大威胁。本研究针对3个生长阶段的裙带菜(Undaria pinnatifida)和同期出现的铜藻,测定二者在不同温度和不同光照强度下的光合速率;本研究设计了温度、光照和培养模式这3个因素:温度1月为5℃,4月为10℃,10月为15和20℃;光照为30、90和180μmol·m^(-2)·s^(-1);培养模式为单养和混养;研究这些因素对藻体的特定生长率(SGR)、碳氮含量和叶绿素含量的影响。研究表明,裙带菜的光合速率在10月高于铜藻,在1月与铜藻持平,在4月低于铜藻。经过12 d的培养,1月裙带菜的SGR略低于铜藻,在低光和高光处理组中,裙带菜单养优于混养;4月裙带菜的SGR均低于铜藻,且铜藻单养的SGR均优于混养;10月裙带菜的SGR均高于铜藻,且在部分处理组中,混养的SGR优于单养。研究结果表明,相同环境条件下,裙带菜在幼苗期(10月)比铜藻更具生长优势,在快速生长期(1月)二者相差不大,在成熟期(4月)生长劣于铜藻。大部分条件下铜藻体内的氮含量和叶绿素含量均高于裙带菜。在实验过程中铜藻比裙带菜更具生长优势,且在自然条件下裙带菜的生长环境劣于漂浮型铜藻,因此本研究判断漂浮型铜藻对裙带菜养殖会造成负面影响。

In recent years,the‘Golden Tide’caused by drifting Sargassum horneri along the coast of East China Sea and Yellow Sea threatened the cultivation of economic algae.At three growth stages of U.pinnatifida and in the same period of S.horneri,a study was conducted on their photosynthetic rates under different temperatures and light densities.Three factor interaction experiments were also conducted at temperatures(5,10,15 and 20℃),light densities(30,90 and 180μmol·m^(-2)·s^(-1))and cultivating modes(monoculture and polyculture).The specific growth rate(SGR),carbon and nitrogen contents and chlorophyll content were determined.The results showed that the photosynthetic rate of U.pinnatifida was higher than that of S.horneri in Oct.,similar with that of S.horneri in Jan.and lower than that of S.horneri in Apr..After 12 day culture experiments,SGR of U.pinnatifida was slightly lower than that of S.horneri,and in the low-light and high-light treatments,the monoculture of U.pinnatifida was superior to polyculture in Jan..The SGRs of U.pinnatifida were all lower than those of S.horneri,and SGRs of S.horneri in monoculture conditions were higher than those in polyculture in Apr..In Oct.,the SGRs of U.pinnatifida were higher than those of S.horneri,and in some treatments,SGRs in polyculture conditions were higher than those in monoculture conditions.It indicated that the growth of U.pinnatifida at seedling stage was favorable than that of S.horneri,and the growth at growing stage was similar with that of S.horneri while the growth of U.pinnatifida in mature period was inferior than that of S.horneri.Nitrogen content and chlorophyll content in S.horneri were higher than those of U.pinnatifida in most conditions.The drifting S.horneri has more growth advantage than U.pinnatifida at two growth stages,and the environment in the field of U.pinnatifida is worse than that of S.horneri.It was inferred that the drifting S.horneri has a negative impact on the cultivation of U.pinnatifida.