Laser fluorescence analysis of phytoplankton across a frontal zone in the California Current ecosystem
Laser fluorescence analysis of phytoplankton across a frontal zone in the California Current ecosystem
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DOI：
10.1093/plankt/fbs034
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发表时间：
2012-09
影响因子：
2.1
通讯作者：
A. Chekalyuk;M. Landry;R. Goericke;Andrew G. Taylor;Mark A. Hafez
中科院分区：
文献类型：
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作者：
A. Chekalyuk;M. Landry;R. Goericke;Andrew G. Taylor;Mark A. Hafez
利用经过校准的先进激光荧光计（ALF），分析了南加州海流生态系统深水密度锋叶绿素、藻胆蛋白、发色溶解有机物和可变荧光（Fv/Fm）的空间变异性，以评估叶绿素浓度（Cchl）、总自养碳（AC）和聚球藻碳生物量（SYN）。确定了三个不同的自养组合。荧光被发现是三到四倍高，在寒冷的中营养沃茨北部的前比温暖的贫营养沃茨南部。北方沃茨的区别是一个浅的色素最大占主导地位的蓝水类型的聚球藻和存在的绿水聚球藻和隐藻，只有蓝水聚球藻检测在较低的浓度南部的前。最高的Cchl和AC值，伴随着升高的Fv/Fm和叶绿素荧光每单位的Cchl，和最小的聚球藻丰度，被发现直接在前面的20-40米深的层占主导地位的硅藻。Fv/Fm与硝酸盐浓度在这一层的协变，沿着在浮游植物群落的结构变化，表明它已产生的原位过程，而不是平流。强的结构响应当地水文也揭示了高频率进行ALF表面采样，检测到一个突然的过渡，从低到高SYN的北方一侧的一个尖锐的盐度梯度在前面。集球藻特异性藻红蛋白荧光（FPE 12）和SYN在地表沃茨中高度相关（R1/4 0.95），而FPE 12：SYN随深度逐渐增加。叶绿素荧光与Cchl（R1/4 0.95）和AC（R1/4 0.79）有很强的相关性。
Spatial variability of chlorophyll, phycobiliproteins, chromophoric dissolved organic matter and variable fluorescence (Fv/Fm) was analyzed across a deepwater density front in the Southern California Current Ecosystem using an Advanced Laser Fluorometer (ALF) calibrated to assess chlorophyll concentration (Cchl), total autotrophic carbon (AC) and Synechococcus carbon biomass (SYN). Three distinct autotrophic assemblages were identified. Fluorescence was found to be three to four times higher in cooler mesotrophic waters north of the front than in warm oligotrophic waters to the south. Northern waters were distinguished by a shallow pigment maximum dominated by a blue-water type of Synechococcus and by the presence of green-water Synechococcus and cryptophytes; only blue-water Synechococcus were detected at lower concentration south of the front. The highest Cchl and AC values, accompanied by elevated Fv/Fm and chlorophyll fluorescence per unit of Cchl, and minimal Synechococcus abundance, were found directly at the front in a 20–40 m deep layer dominated by diatoms. The covariation of Fv/Fm with nitrate concentration in this layer, along with the structural changes in the phytoplankton community, suggest that it had been generated by in situ processes rather than advection. Strong structural responses to the local hydrography were also revealed by high-frequency underway ALF surface sampling, which detected an abrupt transition from low to high SYN on the northern side of a sharp salinity gradient at the front. Synechococcus-specific phycoerythrin fluorescence (FPE12) and SYN were highly correlated in surface waters (R1⁄4 0.95), while FPE12:SYN gradually increased with depth. Strong relationships were found for chlorophyll fluorescence versus Cchl (R 1⁄4 0.95) and AC (R1⁄4 0.79).