Ocean Acidification

Highlights

•The growth of A. tamarense was influenced more strongly by CO₂ than by N sources.

•The toxicity of A. tamarense was influenced more strongly by the N than by CO₂.

•The toxicity of A. tamarense associated with the cell density was best fitted using a logistic function.

•Zebrafish embryo had the detoxication systems to avoid the damage of A. tamarense.

Abstract

The effects and interactive effects of different nitrogen (N) sources (ammonium, nitrate, and urea) and carbon dioxide (CO₂) concentrations were investigated on Alexandrium tamarense, a harmful marine dinoflagellate, by measuring its growth (μ), extracellular carbonic anhydrase (CA), and its toxicity to zebrafish (Danio rerio) embryo. The μ and CA were influenced more strongly by CO₂ concentrations rather than by N sources; significant effects of CO₂ on μ and CA were observed under low CO₂ concentration (LC) conditions compared to high CO₂ concentration (HC) conditions. The ammonium and nitrate media under LC conditions had the maximum μ and CA, which was inhibited under HC conditions. The embryotoxic effects were influenced more strongly by the N sources than by CO₂ concentrations, thus excluding the lower deformation in urea under HC conditions. Moreover, the antioxidant enzymes superoxide dismutase (SOD), glutathione peroxidase (GPX), glutathione S-transferase (GST), and catalase (CAT) were detected in normal (untreated) zebrafish embryos, and among them, the level of SOD was the highest. In summary, this study provides a clear insight for understanding the effects and interactive effects of N sources and CO₂ concentrations on the growth and toxicity of harmful dinoflagellates.

Guan W., Si R., Li X., Cai J. & Chen S., 2018. Interactive effect of nitrogen source and high CO2 concentration on the growth of the dinoflagellate Alexandrium tamarense and its toxicity to zebrafish (Danio rerio) embryos. Marine Pollution Bulletin 133: 626–635. Article (subscription required).