Data_Sheet_2_Acquired Phototrophy and Its Implications for Bloom Dynamics of the Teleaulax-Mesodinium-Dinophysis-Complex.xlsx

The dinoflagellate Dinophysis is responsible for causing diarrhetic shellfish poisoning impacting shellfish aquaculture globally. Dinophysis species are invariably plastidic specialist non-constitutive mixoplankton (pSNCM), combining phagotrophy with acquired phototrophy. Dinophysis acquires phototrophy from another pSNCM, the ciliate Mesodinium, which in turn acquires phototrophy from cryptophytes within the Teleaulax-Plagioselmis-Geminigera clade. Despite this trophic linkage, the temporal dynamics of cryptophyte-Mesodinium-Dinophysis remain poorly understood. In this study, we present the first Teleaulax-Mesodinium-Dinophysis (TMD)-complex system dynamics model. Using this, we explored the dynamics of TMD interactions under different ecological settings. Temperature, nutrient load, mixed layer depth, and irradiance all greatly influenced the timing and magnitude of the TMD-complex interactions and, as a result, Dinophysis bloom duration and peak. Availability of Mesodinium and temporal matching of its growth to that of Dinophysis are also key biotic factors; the timing of Mesodinium availability impacts the potential of Dinophysis growth for up to 3 months. Integrating our TMD-complex model with a suitable hydrodynamic model could greatly improve our understanding of bloom formation and aid in forecasting harmful algal bloom (HAB) events. Future monitoring of Dinophysis would also be enhanced by the monitoring of the precursor prey species, Teleaulax and Mesodinium, which are rarely accorded the same effort as the HAB forming dinoflagellate.

甲藻属（Dinophysis）是全球范围内引发腹泻性贝类中毒的元凶，该毒素会对全球贝类养殖业造成冲击。该属物种均为质体专性非组成型混合营养浮游生物（plastidic specialist non-constitutive mixoplankton, pSNCM），兼具吞噬营养与获得性光养特性。甲藻属的光养特性源自另一种质体专性非组成型混合营养浮游生物——纤毛虫属（Mesodinium），而该纤毛虫的光养特性则源自泰勒藻-偏孢藻-双脊藻分支（Teleaulax-Plagioselmis-Geminigera clade）内的隐藻。尽管存在这种营养联系，但隐藻-纤毛虫-甲藻三者的时间动态机制仍未被充分阐明。本研究构建了首个泰勒藻-纤毛虫-甲藻（Teleaulax-Mesodinium-Dinophysis, TMD）复合系统动力学模型。借助该模型，我们探究了不同生态场景下TMD复合系统的相互作用动态。水温、营养盐负荷、混合层深度以及光照强度均会显著影响TMD复合系统相互作用的发生时机与强度，进而影响甲藻水华的持续时长与峰值规模。纤毛虫的可获得性及其生长与甲藻生长的时间匹配度同样是关键的生物因子；纤毛虫可获得的时机对甲藻生长潜力的影响可长达3个月。将本研究构建的TMD复合系统模型与适配的水动力模型相结合，可大幅提升我们对水华形成机制的认知，并助力有害藻华（harmful algal bloom, HAB）事件的预警预报。未来对甲藻属的监测可通过同步监测其前驱猎物物种泰勒藻与纤毛虫得到优化，而目前针对这两类物种的监测投入远低于对产毒甲藻的监测力度。