Reduced growth with increased quotas of particulate organic and inorganic carbon in the coccolithophore <i>Emiliania huxleyi</i> under future ocean climate change conditions

Abstract

Abstract. Effects of ocean acidification and warming on marine primary producers can be modulated by other environmental factors, such as levels of nutrients and light. Here, we investigated the interactive effects of five oceanic environmental drivers (CO2, temperature, light, dissolved inorganic nitrogen and phosphate) on the growth rate, particulate organic carbon (POC) and particulate inorganic carbon (PIC) quotas of the cosmopolitan coccolithophore Emiliania huxleyi. The population growth rate increased with increasing temperature (16 to 20 ∘C) and light intensities (60 to 240 µmolphotonsm-2s-1) but decreased with elevated pCO2 concentrations (370 to 960 µatm) and reduced availability of nitrate (24.3 to 7.8 µmol L−1) and phosphate (1.5 to 0.5 µmol L−1). POC quotas were predominantly enhanced by the combined effects of increased pCO2 and decreased availability of phosphate. PIC quotas increased with decreased availability of nitrate and phosphate. Our results show that concurrent changes in nutrient concentrations and pCO2 levels predominantly affected the growth, photosynthetic carbon fixation and calcification of E. huxleyi and imply that plastic responses to progressive ocean acidification, warming, and decreasing availability of nitrate and phosphate reduce the population growth rate while increasing cellular quotas of particulate organic and inorganic carbon of E. huxleyi, ultimately affecting coccolithophore-related ecological and biogeochemical processes.

Responses of elemental content and macromolecule of the coccolithophore Emiliania huxleyi to reduced phosphorus availability and ocean acidification depend on light intensity

“…Several studies report that reduced phosphorus availability (0.4-0.5 µmol L -1 ) did not change growth rates significantly during the short-time (2 or 3 days) incubations under low CO2 level and high light intensity (Rokitta et al, 2016;Zhang et al, 2020;Wang et al, 2022) (Fig. S6).…”

“…CC BY 4.0 License. acted antagonistically to affect PIC content of E. huxleyi (Leonardos and Geider, 2005;Matthiessen et al, 2012;Zhang et al, 2020). In addition, ocean acidification normally amplified the positive effect of increasing light intensity on POC content (Rokitta and Rost, 2012;Heidenreich et al, 2019).…”

The need for unrealistic experiments in global change biology

“…Depending on the traits under investigation, this is a challenging but doable experiment. Indeed, both Sett (2014) [19] and Zhang (2020) [25] conducted experiments with enough total experimental units to have calculated rough response surfaces had more levels of temperature been used; both used more CO 2 levels than necessary.…”

Ocean Acidification Affects the Response of the Coastal Coccolithophore Pleurochrysis carterae to Irradiance

“…Previous studies suggest that the calcification of coccolithophores is especially susceptible to OA, but these responses vary between strain or species specificity [ 10 , 11 ]. In general, OA may be detrimental to the coccolith formation and maintenance [ 12 ], resulting in decreased calcification rates and the malformation of coccoliths [ 13 , 14 , 15 , 16 , 17 ]. However, the calcification of the Emiliania huxleyi strain NZEH increased significantly with CO 2 concentration, increasing from 490 to 750 ppm [ 18 ], while the calcification rate of Coccolithus pelagicus remained constant across a range of CO 2 concentrations [ 11 ].…”

“…Coccolithophore blooms in the field are generally observed in environments with a high irradiance [ 21 ]. Previous studies have mainly focused on the sensitivity of the cosmopolitan species Emiliania huxleyi and Gephyrocapsa oceanica to environmental changes [ 13 , 22 , 23 ]. Nonetheless, marine coccolithophores have a global distribution, with a diversity of ~280 morphospecies [ 24 ].…”