Over the last fifteen years, blooms of the genus Ostreopsis have been reported more frequently and at higher abundances in the Mediterranean area. Ostreopsis cf. ovata is known to produce ovatoxins (OVTXs), structural analogues of palytoxin, which is one of the most potent non-polymeric toxins. However, the production of OVTXs is poorly characterized in situ. The present study focuses on toxin content and profile according to the bloom phase during summer 2017 in Villefranche-sur-Mer, France (NW Mediterranean Sea), depth (from 0.5 to 5 m) and three different macroalgal substrates of this epiphytic dinoflagellate (Padina pavonica, Dictyota spp. and Halopteris scoparia). Ovatoxin quantification of all samples was performed by liquid chromatography coupled to tandem mass spectrometry (LC–MS/MS). The bloom started at the end of June and declined in mid-July, showing the typical seasonal pattern of the NW Mediterranean Sea area. The peak was observed on the 10 July with 1.8 × 10⁶ cells/g FW and 1.7 × 10⁴ cells/L for benthic and planktonic cells, respectively. Total toxin content of cells, collected using artificial substrates, increased during the exponential and stationary growth phases. After reaching a maximum concentration of 9.2 pg/cell on 18 July, toxin concentration decreased and remained stable from 25 July until the end of monitoring. A decreasing trend of the abundance and of the associated total toxin content was noted with depth. Finally, the decreasing order of maximal epiphytic concentration of O. cf. ovata was: Dictyota spp. (8.3 × 10⁵ cells/g FW), H. scoparia (3.1 × 10⁵ cells/g FW) and P. pavonica (1.6 × 10⁵ cells/g FW). Interestingly, the highest OVTX quota was obtained in cells present on Halopteris scoparia, then on Dictyota spp. and Padina pavonica. This suggests that the nature of the macroalgal substrate influences both growth and toxin production of O. cf. ovata and further work will be required to understand the underlying mechanisms (e.g., competition for nutrition, pH or allelopathic interaction). However, the toxin profiles (i.e., the proportion of each ovatoxin analogue) were not affected by any of the studied parameters (bloom phase, depth, macroalgae or artificial substrates).

在过去的十五年中，据报道，在地中海地区，骨绿藻类植物的绽放更为频繁，且丰度更高。骨质疏松症cf. 已知卵形蛋白会产生卵形毒素（OVTX），卵形毒素是结构最强的非聚合毒素之一，其结构类似物。但是，OVTX的生产原位表征不佳。本研究重点研究了2017年夏季法国滨海自由城（地中海西北部）盛花期的毒素含量和分布，深度（0.5至5 m）和这种附生鞭毛鞭藻酸盐（Padina的三种不同藻类基质）pavonica，Dictyota spp。和Halopteris scoparia）。液相色谱-串联质谱（LC-MS / MS）对所有样品的卵毒素进行定量。盛开于6月底开始，7月中旬开始下降，显示出西北地中海地区的典型季节性格局。在7月10日观察到该峰值，其FW为1.8×10 ^6个细胞/ g，FW为1.7×10 ^4个底栖细胞和浮游细胞的细胞数/ L。使用人工底物收集的细胞总毒素含量在指数生长期和固定生长期增加。在7月18日达到最高浓度9.2 pg /细胞后，毒素浓度下降并从7月25日到监测结束一直保持稳定。随着深度的增加，丰度和相关的总毒素含量呈下降趋势。最后，的最大浓度附生的降序O.比照 ovata是：Dictyota spp。（8.3×10 ^5个细胞/ g FW），南瓜子（3.1×10 ^5个细胞/ g FW）和pavonica（1.6×10 ⁵个细胞/克FW）。有趣的是，最高的OVTX配额是在Halopteris scoparia，然后在Dictyota spp上的细胞中获得的。和帕迪纳·帕沃尼卡（Padina pavonica）。这表明，大型藻类基质的性质会影响O的生长和毒素产生。cf. 卵子和进一步的工作将需要了解潜在的机制（例如，竞争营养，pH或化感相互作用）。但是，毒素谱（即每种卵毒素类似物的比例）不受任何研究参数（开花相，深度，大型藻类或人工底物）的影响。