Recently, an article entitled “Decreased motility of flagellated microalgae long-term acclimated to CO₂-induced acidified waters” was published on Nature Climate Change by a team from YSFRI led by Professor YE Naihao. The new findings show acidification impairs the swimming ability of flagellated microalgae, suggesting that their capacity to survive is threatened in a high CO₂ world.

Phytoplankton play a key role in aquatic ecosystems: they are responsible for about half of global carbon fixation, they form the base of the aquatic food web and they drive biogeochemical cycles. For these microscopic phytoplankton, the motility plays a critical role in survival and reproduction, with implications for aquatic ecosystem stability. However, the effect of elevated CO₂ on marine, brackish and freshwater algal motility is unclear.

It was shown that three typical phytoplankton species, Polar marine Microglena sp., euryhaline Dunaliella salina and freshwater Chlamydomonas reinhardtii, had decreased motility with increased CO₂, which were grown under different CO₂ concentrations for five years. Long-term acclimated Microglena sp. decreased photo-responses significantly in all treatments, with a photophobic reaction affecting intracellular calcium concentration. Genes regulating flagellar movement were significantly down-regulated, alongside a significant increase in gene expression for flagellar shedding. D. salina and C. reinhardtii showed similar results, suggesting that motility changes are common across flagellated species. As the flagella structure and bending mechanism are conserved from unicellular organisms to vertebrates, these results suggest increasing surface water CO₂ concentrations may affect flagellated cells from algae to fish.

The first author of the article is WANG Yitao, a member of the research team led by Professor YE Naihao and the corresponding authors is Professor YE Naihao. The researchers from Xiamen University, Monash University (Australia), University of Tsukuba(Japan), University of Plymouth(United Kingdom), and University of Tasmania (Australia) also participated in this study.

Links for full text：https://www.nature.com/articles/s41558-020-0776-2；DOI: 10.1038/s41558-020-0776-2.

Fig. 1 Effect of ocean acidification on the velocity of Microglena sp

Fig. 2 Mechanism of response and regulation of Microglena sp flagella motility under ocean acidification

Fig. 3 Effects of ocean acidification and sea ice melt on Microglena sp motility