Effects of Nitric Oxide On The Growth of The Marine Microalgae And The Parameters of Carbonate Chemistry

Abstract Nitric oxide (NO) is a non-traditional regulator for the growth of plant and phytoplankton. This study monitored the growth of five marine phytoplankton species, namely, Platymonas helgolandica var. tsingtaoensis, Platymonas subcordiformis, Skeletonema costatum, Gymnodinium sp., and Prorocentrum donghaiense, and examined the parameters of the carbonate system in the culture media after adding different concentrations of NO and sodium nitroprusside (SNP, NO donor) solutions. The different concentrations of exogenous NO had various roles in the growth of these microalgae. The two food algae,namely, P. helgolandica var. tsingtaoensis, P. subcordiformis, and three red tide algae, namely S. costatum, Gymnodinium sp., and P. donghaiense showed different responses to the same NO concentration. The red tide algae were more sensitive to exogenous NO than the food algae. NO with the concentration of 1.4 × 10− 6 mol L− 1 had the optimum stimulatory effect on the growth of the microalgae, the cell density increased by 9.8 ~ 38.3%. SNP solution with the concentration of 100 µmol L− 1 inhibited the growth of the two food algae, the cell density decreased by 38.8 ~ 84.3%. Meanwhile, 10 µmol L− 1 SNP solution additions to the three red tide algae declined the cell density by 95.3 ~ 99.9%. Low concentrations of SNP (0.1 µmol L− 1 for the two food algae and 0.01 µmol L− 1 for the red tide algae) promoted the growth of microalgae slightly. Different concentrations of exogenous NO could also influence parameters of the carbonate system in the culture media. NO participates in the regulation of marine microalgae photosynthesis, which may influence the parameters of carbonate system.