A dense bloom of Protoperidinium steinii was observed in the backwaters adjoining the western Bay of Bengal, Kalpakkam coast, which might be the first report for the world oceans. The brownish-red bloom appeared on 2 October 2019, and it was monitored on alternate days up to 14 October. Surface water temperature was about 27.5°C and salinity was <17 PSU during the bloom. Dissolved inorganic nutrients like nitrate, ammonia, silicate, and phosphate were extremely high compared to that of the coastal waters. The chlorophyll-a maxima (20.95 mg m⁻³) coincided with the highest Protoperidinium density (113.9 × 10⁴ cells l⁻¹). The contribution of P. steinii ranged from 17−93% of the total phytoplankton population. Since P. steinii is a heterotroph and voracious grazer, low autotroph density was observed during the bloom. No mass mortality of fish or other organisms was observed, thereby indicating the non-toxic nature of the bloom.

在毗邻孟加拉湾西部、卡尔帕卡姆海岸的死水中观察到了大量的Protoperidinium steinii，这可能是世界海洋的第一份报告。棕红色花朵出现在 2019 年 10 月 2 日，并在直到 10 月 14 日的隔日进行监测。开花期间地表水温约为 27.5°C，盐度 <17 PSU。与沿海水域相比，硝酸盐、氨、硅酸盐和磷酸盐等溶解的无机养分含量极高。叶绿素a最大值（20.95 mg m ^-3）与最高的Protoperidinium密度（113.9 × 10 ⁴细胞 l ^-1）一致。P. steinii的贡献占总浮游植物种群的 17-93%。由于P. steinii是一种异养和贪婪的食草动物，因此在开花期间观察到低自养密度。没有观察到鱼类或其他生物的大量死亡，从而表明水华的无毒性质。