Acquired Phototrophy and Its Implications for Bloom Dynamics of the Teleaulax-Mesodinium-Dinophysis-Complex

Anna-A Anschütz,Aditee Mitra,Kevin J Flynn

doi:10.3389/fmars.2021.799358

Abstract

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.

Highlights

Dinophysis is a harmful dinoflagellate of global distribution (Figure 1) that is the causative agent for diarrhetic shellfish poisoning (DSP) events leading to the closure of aquaculture facilities
While our study shows the importance of prey availability for the growth of Dinophysis, it shows that the timing of prey availability has a significant effect on the spatiotemporal dynamics of the TMD-complex
Simulations of the mixoplanktonic activity of these mixoplankton, configured in this study against data for D. acuminata and its prey M. rubrum, both with their special needs for acquired phototrophy, play an important role in the dynamics of bloom formation. Both high M. rubrum to D. acuminata ratios and the growth phase in which D. acuminata encounters M. rubrum are expected to affect cell abundances of D. acuminata in subsequent blooms. Even though they are not simulated in this study, it is very likely that these effects extend to other species from the genera Mesodinium and Dinophysis that share a similar relationship within cryptophyteMD-complex

Summary

Introduction

Dinophysis is a harmful dinoflagellate of global distribution (Figure 1) that is the causative agent for diarrhetic shellfish poisoning (DSP) events leading to the closure of aquaculture facilities (review by Reguera et al, 2012, 2014). Traditional methods of monitoring Dinophysis by counting cells and using satellite chlorophyll concentrations are not robust for forecasting blooms of these species (Ruiz-Villarreal et al, 2016). This is because the cell concentration threshold for Dinophysis, at which this organism can pose a threat, is only 200 cells L−1 (Yasumoto et al, 1985), a cell abundance level that can be very difficult to detect (Berdalet et al, 2017). There is still a lack of predictive power in the existing models suggesting that there may be one or more key features missing from these models, for example, the biological characteristics (Ajani et al, 2016; Moita et al, 2016)

Results

Discussion

Conclusion