Highlights
- High level CO2 significantly promoted growth of toxic Alexandrium minutum.
- Total yields of paralytic shellfish toxins by A. minutum were enhanced by rising CO2.
- Rising CO2 promoted transformation from GTX2&3 to more potent GTX1&4.
- High level CO2 may depress the release of PSTs from inside to outside of the cells.
- All the processes collectively increase the risk of A. minutum under CO2 enrichment.
Abstract
Ocean acidification caused by increasing emission of carbon dioxide (CO2) is expected to have profound impacts on marine ecological processes, including the formation and evolution of harmful algal blooms (HABs). We designed a set of experiments in the laboratory to examine the effects of increasing CO2 on the growth and toxicity of a toxic dinoflagellate Alexandrium minutum producing paralytic shellfish toxins (PSTs). It was found that high levels of CO2 (800 and 1,200 ppm) significantly promoted the growth of A. minutum compared to the group (400 ppm) representing the current CO2 level. The total yields of PSTs by A. minutum, including both intracellular and extracellular toxins, were significantly enhanced, probably due to the induction of core enzyme activity and key amino acids synthesis for PST production. More interestingly, high level of CO2 promoted the transformation from gonyautoxin2&3 to gonyautoxin1&4 and depressed the release of PSTs from inside to outside of the cells. All these processes collectively led to an apparent increase of A. minutum toxicity. Our study demonstrated that rising CO2 would increase the risk of toxic A. minutum based on the comprehensive analyses of different processes including algal growth and toxin synthesis, transformation and release.
Lian Z., Li F., He X., Chen J. & Yu R.-C., 2022. Rising CO2 will increase toxicity of marine dinoflagellate Alexandrium minutum. Journal of Hazardous Materials 431: 128627. doi: 10.1016/j.jhazmat.2022.128627. Article (subscription required).
