Aluminum (Al) is abundant and ubiquitous in the environment. However, little information is available on its effects on photosynthetic microbes in alkaline seawater. Thus, we investigated the physiological performance in the most cosmopolitan coccolithophorid, viz., Emiliania huxleyi, grown under low (410 µatm) and high (1000 µatm) CO2 levels in seawater having none (0 nM, NAl), low (0.2 µM, LAl) and high (2 µM, HAl) Al concentrations. Under low CO2 conditions, the specific growth rate showed no significant difference between the NAl and LAl treatments, which was higher than the HAL treatment. Elevated CO2 inhibited the growth rate in the NAl and LAl cultures but did not affect the HAl cultures. The addition of Al had no effects on (LAl) or slightly elevated (HAl) the particulate organic carbon (POC) production rate under low CO2 conditions. With increasing CO2 concentration, the production rate of POC was enhanced by 55.3 % during the NAl treatment and further increased by 22.3 % by adding 0.2 µM Al. The responses of particulate organic nitrogen (PON) production rate, cellular POC, and PON contents to the different treatments revealed the same pattern as those of the POC production rate. The particulate inorganic carbon (PIC) production rate and PIC/POC ratio were not affected by Al under low CO2 conditions. They were significantly decreased by elevated CO2 in the LAl and HAl cultures. Our results indicate that high CO2 could increase carbon export to ocean depths by elevating the efficiency of the biological pump at low Al levels occurring in natural seawater (0.2 μM), with potentially significant implications for the carbon cycle of the ocean under accelerating anthropogenic influences.
Gao L., Tong S., Zhong Z., Qiao H., Zou N., Shi X., Sun Y. & Chang X., 2023. Enormously enhanced particulate organic carbon and nitrogen production by elevated CO2 and moderate aluminum enrichment in the coccolithophore Emiliania huxleyi. Fundamental and Applied Limnology 196(2): 155 – 163. Article.
