Exposure of engineered nanoparticles to Alexandrium tamarense (Dinophyceae): Healthy impacts of nanoparticles via toxin-producing dinoflagellate.

Human activities can enhance the frequency, intensity and occurrence of harmful algal blooms (HABs). Engineered nanoparticles (ENPs), contained in many materials, will inevitably enter coastal waters and thus cause unpredictable impacts on aquatic organisms. However, knowledge of the influence of ENPs on HAB species is still lacking. In this study, we examined the effects of titanium dioxide nanoparticles (TiO), zinc oxide nanoparticles (ZnO) and aluminum oxide nanoparticles (AlO) on physiological changes and paralytic shellfish poisoning toxins (PSTs) production of Alexandrium tamarense. We found a dose-dependent decrease in photosynthetic activity of A. tamarense under all three ENPs and a significant growth inhibition induced by ZnO. The largest reactive oxygen species (ROS) production was induced by TiO, followed by ZnO and AlO. Moreover, the PSTs production rate increased by 3.9-fold for TiO (p<0.01) and 4.5-fold for AlO (p<0.01) at a concentration of 200mgL. The major component, C2 was transformed to its epimer C1 and the proportion of decarbamoyl toxins increased under 200mgL of ZnO and AlO. In addition, the proportion of carbamate toxins increased upon exposure to 2mgL ENPs, while decreased upon exposure to 200mgL ENPs. The changes in PSTs production and composition might be an adaptive response for A. tamarense to overcome the stress of ENPs exposure. This work brings the first evidence that ENP would affect PSTs production and profiles.