Shan Shihan, Xu Lei, Chen Ke, Tong Mengmeng, Wang Xiaoping
Ocean College, Zhejiang University, Zhoushan, Zhejiang 316021, China; Key Laboratory of Ocean Observation-Imaging Testbed of Zhejiang Province, Zhejiang University, Zhoushan, Zhejiang 316021, China.
Zhejiang Veelang Environment Technology Co., Ltd, Hangzhou, Zhejiang 310000, China.
Spectrochim Acta A Mol Biomol Spectrosc. 2022 Aug 5;276:121216. doi: 10.1016/j.saa.2022.121216. Epub 2022 Mar 30.
Detecting the marine phytoplankton by the means of absorption or fluorescence spectra were successfully deployed in the past decades, however, the differentiation are mainly limited in levels of class, such as bacillariophytas, dinophytas, raphidophytes, chlorophytes, cyanobacteria, etc. which are characterized by their specific composition of photosynthetic pigments. To further differentiate the typical dinoflagellate Prorocentrum donghaiense, Amphidinium carterae, Scrippsiella trochoidea, Karenia mikimotoi out of the common diatom Skeletonema costatum and haptonema Phaeocystis globosa at East China Sea, a rapid 3D-fluorescence method equipped with CHEMTAX model were conducted. Initial fluorescence excitation spectra of each algal species (under variable environmental conditions) were captured by 3D-fluorometer first. Then fingerprints of each algae were characterized by ten-point discrete excitation spectrum with the excitation wavelengths of 405, 420, 435, 470, 490, 505, 535, 555, 570 and 590 nm, which closely reflecting the difference of photosynthetic pigments. By equipping with CHEMTAX model, the standard spectra and norm spectra were constructed for FS-CHEMTAX (Fluorescence spectra-CHEMTAX) model to further identify the algal species and estimate the cell density. The developed method performed a better way of identifying the toxic species Amphidinium carterae, Phaeocystis globosa, and Karenia mikimotoi out of the non-toxic ones, with the identification accuracy rates of 83.3%, 90% and 100%, in monocultures, and 77.8%, 90% and 100%, in the bi-mixed cultures, respectively. Meanwhile, the detection limits for the three toxic species were found as low as 250, 1,400 and 120 cells/mL. The concentrations estimated are in good agreement with the microscopic cell counts for all the algae groups (correlation coefficients (R) exceed 0.8). The relative error of predict concentration was lowest for small cells, i.e., Phaeocystis globosa (10.0%) and Amphidinium carterae (21.1%), but the highest for big cells, i.e. Karenia mikimotoi (41.8%) when the target algae become the dominant species. The overall concentration detection error was no more than one order of magnitude, indicating that this method could provide an important technical support for monitoring the related harmful algal blooms.
在过去几十年中，通过吸收光谱或荧光光谱检测海洋浮游植物已成功应用，然而，这种区分主要局限于纲的层面，例如硅藻纲、甲藻纲、裸藻纲、绿藻纲、蓝藻纲等，它们以其特定的光合色素组成而著称。为了进一步区分东海常见硅藻中肋骨条藻和球石藻中的典型甲藻东海原甲藻、卡氏前沟藻、锥状斯氏藻、米氏凯伦藻，采用了配备CHEMTAX模型的快速三维荧光法。首先用三维荧光计采集每种藻类在不同环境条件下的初始荧光激发光谱。然后用激发波长为405、420、435、470、490、505、535、555、570和590nm的十点离散激发光谱对每种藻类的指纹进行表征，该光谱能密切反映光合色素的差异。通过配备CHEMTAX模型，构建了FS-CHEMTAX（荧光光谱-CHEMTAX）模型的标准光谱和归一化光谱，以进一步识别藻类物种并估计细胞密度。所开发的方法在识别无毒物种中的有毒物种卡氏前沟藻、球石藻和米氏凯伦藻方面表现良好，在单培养物中的识别准确率分别为83.3%、90%和100%，在双混合培养物中的识别准确率分别为77.8%、90%和100%。同时，发现这三种有毒物种的检测限低至250、1400和120个细胞/毫升。估计的浓度与所有藻类群体的显微镜细胞计数结果高度一致（相关系数（R）超过0.8）。当目标藻类成为优势物种时，预测浓度的相对误差对于小细胞（即球石藻，10.0%）和卡氏前沟藻（21.1%）最低，但对于大细胞（即米氏凯伦藻，41.8%）最高。总体浓度检测误差不超过一个数量级，表明该方法可为监测相关有害藻华提供重要技术支持。
