Rising pCO2 interacts with algal density to reversely alter physiological responses of Gracilaria lemaneiformis and Ulva conglobata

作者：Li, Gang; Mai, Guangming; Zhang, Jiejun; Ni, Guangyan; Shi, Xiaohan; Tan, Yehui; Zou, Dinghui^*

来源：Algal Research-Biomass Biofuels and Bioproducts, 2021, 54: 102231.

DOI：10.1016/j.algal.2021.102231

• Algal biomass density
• Elevated pCO(2)
• Photosynthetic activity
• Respiration
• Gracilaria lemaneiformis
• Ulva conglobata

In nature growing of macroalgae increases their biomass densities, which alters the surrounding environments and in turn affects their photophysiologies. Photosynthetic performances were explored for two common and widely spread macroalgae species, a branched Gracilaria lemaneiformis (Rhodophyta) and a thin, sheet-like Ulva conglobata (Chlorophyta), responding to a matrix of biomass densities (1.0, 2.0 and 4.0 g L-1) and pCO(2) (400 and 800 ppm). In all three biomass densities the photosynthetic capability of G. lemaneiformis was enhanced by elevated pCO(2), but that of U. conglobata was reduced. The photosynthesis versus irradiance (P vs. E) curve-derived parameters [i.e., light-utilizing efficiency (a), saturating light irradiance (EK) and maximum photosynthetic rate (Pmax)] of G. lemaneiformis generally increased with increasing densities under both ambient and elevated pCO(2), as did the dark respiration (Rd); but the a, EK, Pmax and Rd of U. conglobata decreased. The elevated pCO(2) increased the a, EK and Pmax but decreased the Rd of G. lemaneiformis in all three densities, while the opposite effects occurred in the U. conglobata. Accordingly, the elevated pCO(2) enhanced the integrated daily production of G. lemaneiformis by 62%, but reduced that of U. conglobata by 26%, indicating that rising pCO(2) favors the photosynthesis of branched G. lemaneiformis but reduces that of sheet-like U. conglobata. We propose that the changes in algal density greatly mediate their physiological responses to increasing ambient CO2.

• 单位
  中国科学院研究生院