Blooms of ichthyotoxic microalgae pose a great challenge to the aquaculture industry world-wide, and there is a need for fast and specific methods for their detection and quantification in monitoring programs. In this study, quantitative real-time PCR (qPCR) assays for the detection and enumeration of three ichthyotoxic flagellates: the dinoflagellate Karenia mikimotoi (Miyake & Kominami ex Oda) Hansen & Moestrup and the two raphidophytes Heterosigma akashiwo (Hada) Hada ex Hara & Chihara and Fibrocapsa japonica Toriumi & Takano were developed. Further, a previously published qPCR assay for the dinoflagellate Karlodinium veneficum (Ballantine) Larsen was used. Monthly samples collected for three years (Aug 2009–Jun 2012) in outer Oslofjorden, Norway were analysed, and the results compared with light microscopy cell counts. The results indicate a higher sensitivity and a lower detection limit (down to 1 cell L⁻¹) for both qPCR assays. Qualitative and semi-quantitative results were further compared with those obtained by environmental 454 high throughput sequencing (HTS, metabarcoding) and scanning electron microscopy (SEM) examination from the same samplings. All four species were detected by qPCR and HTS and/or SEM in outer Oslofjorden (Aug 2009–Jun 2012); Karlodinium veneficum was present year-round, whereas Karenia mikimotoi, Heterosigma akashiwo and Fibrocapsa japonica appeared mainly during the autumn in all three years. This is the first observation of Fibrocapsa japonica in Norwegian coastal waters. This species has previously been recorded off the Swedish west coast and German Bight, which may suggest a northward dispersal.

鱼鳞毒素微藻的大量繁殖对全世界的水产养殖业构成了巨大的挑战，因此需要一种快速，特定的方法来检测其并在监测计划中进行定量。在这项研究中，定量实时PCR（qPCR）测定法用于检测和枚举三种鱼鳞有毒鞭毛：鞭毛鞭毛纲（Miyake和Kominami，出自Oda）Hansen＆Moestrup，以及两种斜纹夜蛾Heterosigma akashiwo（Hada），哈达（Hada），原名Hara＆开发了Chihara和Fibrocapsa japonica Toriumi＆Takano。此外，先前公布的定量PCR检测为甲藻Karlodinium veneficum（Ballantine）使用了拉森（Larsen）。分析了在挪威奥斯陆峡湾外的三年（2009年8月至2012年6月）收集的每月样本，并将结果与​​光学显微镜下的细胞计数进行了比较。结果表明，两种qPCR分析均具有更高的灵敏度和更低的检测限（低至1个细胞L ^-1）。定性和半定量结果与通过环境454高通量测序（HTS，元条形码）和扫描电子显微镜（SEM）从同一采样中获得的结果进行了进一步比较。通过qPCR和HTS和/或SEM在Oslofjorden外部检测到所有四个物种（2009年8月至2012年6月）；全年有Karelenium v​​eneficum，而Karenia mikimotoi，Heterosigma akashiwo和Fibrocapsa japonica全年都有主要出现在这三年的秋季。这是在挪威沿海水域首次观察到的Fibrocapsa japonica。先前已在瑞典西海岸和德国湾附近记录到该物种，这可能表明其向北扩散。