External carbonic anhydrase and affinity for inorganic carbon in intertidal macroalgae

Short-term effects of increasing CO2, nitrate and temperature on three Mediterranean macroalgae: biochemical composition

“…In this study, the results of short-term effects of pCO 2 , nitrate and temperature increases on the physiology of 3 abundant eulittoral Mediterranean macroalgae with different morphological, bio-optical and physiological characteristics (Mercado et al 1998, Figueroa et al 2003a, 2014b, Abdala-Díaz et al 2006) are presented. Combined effects of CO 2 (LC and HC) and nitrogen (LN and HN nitrate concentration through morning pulses) under 2 temperature conditions were tested (6 d at ambient temperature followed by 3 d after a 4°C increase).…”

“…Although increasing ocean CO 2 concentration may enhance rates of photosynthesis and growth, particularly in species without carbon concentrating mechanisms (CCMs), such increases may be limited by the availability of other limiting nutrients (Raven et al 2005). Mercado et al (1998) reported a relationship between CCMs and light energy availability in intertidal macroalgae, but not with inorganic carbon availability: intertidal algae with emersion periods presented higher photosynthetic rates (Mercado et al 1998) and carbon uptake (Flores-Moya et al 1998) due to the higher availability of CO 2 compared to submerged algae. Seasonal changes in temperature, nutrient availability and light are also likely to interact with the effect of CO 2 on metabolic processes in algae (Tyrell et al 2008, Martin & Gattuso 2009, Mercado & Gordillo 2011.…”

“…Finally, the calcareous Ellisolandia elongata (J. Ellis & Solander, K. R. Hind & G. W. Saunders), formerly Corallina elongata J. Ellis et Solander (Rhodophyta) according to Hind & Saunders (2013), presents a complex pseudoparenchymatic morphology with a thick calcareous thallus, cortical and medullar cells, slow growth rate, and contains mycosporine-like amino acids (MAAs), as do other red algae. These macroalgal species were selected since they are dominant species on the Mediterranean coast of the southern Iberian Peninsula and possess different morphologies, bio-optical properties and carbon ac quisition efficiencies; in addition, their ecophysiological responses have been extensively studied in these or similar species (Mercado et al 1998, Figueroa & Viñegla 2001, Gordillo et al 2001, Abdala-Díaz et al 2006, Cabello-Pasini et al 2011.…”

Ocean acidification effects on calcifying macroalgae

“…These mechanisms reduce the competition of oxygen for the enzyme by increasing the intracellular CO 2 :O 2 ratio, thereby making it more efficient by reducing photorespiration (see Raven 1997, 2003, Raven et al 2012 for reviews). CCMs have been reported in many macroalgal species, and are well documented and described among the green algae (Chlorophyta), and many of the red algae (Rhodophyta) and brown algae (Phaeophyta) also contain CCMs (Axelsson & Uusitalo 1988, Drechsler & Beer 1991, Axelsson et al 1995, Mercado et al 1998, Moulin et al 2011, Raven et al 2012. Algae that do not contain efficient CCMs, particularly those growing at depth, could be more stimulated by elevated pCO 2 than those that contain highly efficient CCMs, although algae that use HCO 3 − could also benefit by down-regulating their CCMs under elevated pCO 2 because such CCMs have high energy demands (see Wu et al 2008).…”

Photosynthetic inorganic carbon utilization of gametophytes and sporophytes of Undaria pinnatifida (Phaeophyceae)

“…It is well recognized that the activity of carbonic anhydrase is involved in the utilization of HCO 3 Ϫ during the period of photosynthesis (Johnston 1991;Haglund et al 1992;Mercado et al 1998). The extracellular CA catalyzes the conversion of HCO 3 Ϫ to CO 2 , which is taken up through the plasma membrane and then fixed in photosynthesis.…”