Highlights
- Growth rates of two diatoms remained insensitive to fluctuating pH or seawater acidification.
- Fluctuating pH enhanced the light-saturated photosynthetic rate of the diatom Thalassiosira weissflogii by 20%.
- Photosynthetic rates of two diatoms remained unaltered in response to acute pH changes ranging from 7.2 to 8.4.
Abstract
Coastal waters undergo dynamic changes in seawater carbonate chemistry due to natural and anthropogenic factors. Despite this, our current understanding of how coastal phytoplankton respond to fluctuating pH is limited. In the present study, we investigated the physiological responses of two coastal diatoms Thalassiosira pseudonana and Thalassiosira weissflogii to seawater acidification and diurnally fluctuating pH under natural solar irradiance. Seawater acidification did not significantly impact the growth, maximum and effective quantum yield of PSII, and photosynthetic rates of the two species. However, it did increase the maximum relative electron transport rate of T. weissflogii by 11%. Overall, fluctuating pH had neutral or positive effects on both species. It enhanced the light-saturated photosynthetic rate of T. weissflogii by 20% compared to cells grown under seawater acidification condition. Results from the short-term pH exposure experiment revealed that the photosynthetic rates of both species remained unaffected by acute pH changes, indicating their tolerance to varying pH. Nevertheless, it is crucial to consider dynamic pH when predicting changes in primary production in coastal waters, given the interplay of various environmental drivers.
Shang Y., He J., Qiu J., Hu S., Wang X., Zhang T., Wang W., Yuan X., Xu J. & Li F., 2024. The tolerance of two marine diatoms to diurnal pH fluctuation under dynamic light condition and ocean acidification scenario. Marine Environmental Research 196: 106425. doi: 10.1016/j.marenvres.2024.106425. Article(subscription required).
