Inorganic carbon acquisition by red seaweeds grown under dynamic light regimes

Abstract

Palmaria palmata, which is able to use HCO3 as a carbon source for photosynthesis, and Lomentaria articulata, which is dependent on diffusive uptake of dissolved C02, were grown under constant light and light with sunflecks designed to model wave-induced fluctuations of near-shore underwater light . Both species exhibited significantly increased stable carbon isotope discrimination (more negative values of 8 13 C relative to PDB) when grown with sunflecks . More negative 8 133 C values were associated with decreased growth rate of P palmata but not of L. articulata . The contrasting effects of sunflecks on the carbon-use characteristics of the two species are discussed in terms of the energetic cost of HCO3 use and the susceptibility of CO2 diffusion-dependent species to photoinhibition .

CO 2 concentrating mechanisms and environmental change

“…There are data on the effects of PAR (instantaneous flux and daylength), temperature, carbon dioxide and oxygen, generally in pairs, on the rate of photosynthesis and, in some cases, growth in organisms lacking CCMs (Salvucci and Bowes, 1981;Maberly, 1985a,b;Johnston et al, 1992;Maberly et al, 1992;Kübler and Raven, 1996a;Kübler et al, 1999;Sherlock and Raven, 2001;Raven et al, 2005a;Maberly et al, 2009). It must be borne in mind that the distinction between aquatic organisms with and without CCMs is not as clear as that between C 3 and C 4 terrestrial plants, and the 'intermediate' organisms are not readily assigned to a category like the (admittedly heterogeneous) assemblage of C 3 -C 4 intermediate terrestrial vascular plants (Salvucci and Bowes, 1981;Sherlock and Raven, 2001;Raven et al, 2005a;Maberly et al, 2009).…”

CYANOBACTERIAL ACCLIMATION TO RAPIDLY FLUCTUATING LIGHT IS CONSTRAINED BY INORGANIC CARBON STATUS1

“…In natural phytoplankton (Stramski et al 1993), cultured planktonic eukaryotic algae (Terry 1986, Walsh andLegendre 1988) and macrophyte algae (Dromgoole 1987, 1988, Kübler and Raven 1996 and in the cyanobacteria in this study, photosynthesis decreased in light slowly fluctuating between limiting and saturating levels, when compared with photosynthesis under steady light applied at the same integrated photon dose. As the period of light fluctuation FIG.…”

“…In natural phytoplankton (Stramski et al 1993), cultured planktonic eukaryotic algae (Terry 1986, Walsh and Legendre 1988) and macrophyte algae (Dromgoole 1987, 1988, Kübler and Raven 1996) and in the cyanobacteria in this study, photosynthesis decreased in light slowly fluctuating between limiting and saturating levels, when compared with photosynthesis under steady light applied at the same integrated photon dose. As the period of light fluctuation decreases toward zero (steady light), a hyperbolic increasing “enhancement” of photosynthetic rate per absorbed photon occurred because of the functional integration of the bright and dim (or dark) phases of the fluctuating light (Terry 1986).…”

“…Quéguiner and Legendre (1986) showed a similar acclimation in diatoms, with increased photosynthetic rate in cells acclimated to growth under fluctuating light compared with cells grown under steady light or compared with cells grown under a fluctuating light of a different period. In an analogous comparison of the responses of two macrophytes to fluctuating light, Kübler and Raven (1996) showed a 40% depression of photosynthesis (as biomass gain) in a rapidly growing CCM‐operating macrophyte but not in a slow growing non‐CCM macrophyte. The carbon‐limited slow growth rate of the non‐CCM macrophyte likely meant it was at light saturation even during the dim phase of the fluctuating regime and was therefore not benefiting from integration of the bright and dim phases.…”

A fully automated system for measurements of photosynthetic oxygen exchange under immersed conditions: an example of its use in Laminaria digitata (Heterokontophyta: Phaeophyceae)

“…Indeed, photosynthetic activity has been found to change with light quantity and quality (Drew 1983b;Dromgoole 1987Dromgoole , 1988Dunton and Jodwalis 1988;Falkowski and Laroche 1991;Falkowski and Raven 1997;Gerard 1984;Kubler and Raven 1996). Measurements performed at depth take into account natural irradiance reaching the bottom, its variation and spectral quality.…”