九龙江河-海系统夏季浮游植物磷胁迫研究

PHYTOPLANKTON PHOSPHORUS STRESS OF JIULONGJIANG RIVER-ESTUARY AND ADJACENT WATERS SYSTEM IN SUMMER

采用群落水平和细胞水平碱性磷酸酶活性(APA)相结合的方法,研究了2010年夏季(6—7月)九龙江河-海系统(河流-河口-邻近海域)浮游植物的磷胁迫,结果表明,单位叶绿素a的APA在河流下游区[(48.80±14.69)nmol/(h·μgChla)]显著高于河口区[(10.60±15.58)nmol/(h·μgChl.a)]和邻近海域[(23.54±25.41)nmol/(h·μgChl.a)],表明河流区的浮游植物磷胁迫显著高于河口区和邻近海域。三个区域高比例的游离态APA表明该水域浮游植物已较长时间处于磷胁迫状态。细胞水平的浮游植物荧光标记结果显示,河口区(20%±20%)与邻近海域(38%±20%)无显著差异(P>0.05),此结果与群落水平APA结果相一致;但河口-邻近海域浮游植物的标记比例显著高于河流下游区(9%±3%)(P<0.05)。

Phosphorus stress of phytoplankton was determined by using bulk and single-cell alkaline phosphatase activity （APA） assays during summer （June--July 2010） in Jiulongjiang River-Estuary and adjacent waters system. Results showed that Chl.a-normalized APA was significantly higher in the lower Jiulongjiang River [（48.80±14.69）nmol/（h.μgChl.a）] than the estuary and adjacent coastal waters [（10.60±15.58）nmol/（h.μgChl.a） and （23.54±25.41）nmol/（h.μgChl.a）, respectively], indicating that phytoplankton phosphorus stress was more serious in the lower Jiulongjiang River than that in the estuary and coastal waters. High soluble APA contribution indicated that phytoplankton suffered long-term phosphorus （P） stress in the river-estuary-coastal water system. Single-cell ELF labeling of phytoplankton showed that there was no sig-nificant difference between the estuary （20%±20%） and adjacent coastal waters （38%±20%）, which was coincided with the results of bulk APA. However ELF labeling of phytoplankton in estuary-coastal waters was significantly higher than that in the lower Jiulongjiang River （9%±3%） （P〈0.05）.