A novel in situ system to evaluate the effect of high CO2 on photosynthesis and biochemistry of seaweeds

Abstract

Previous studies of the impact of increased CO 2 on macroalgae have mainly been done in laboratories or mesocosm systems, placing organisms under both artificial light and seawater conditions. In this study, macroalgae were incubated in situ in UV-transparent cylinders under conditions similar to the external environment. This system was tested in a short-term study (5.5 h incubation) on the effect of 2 partial pressures of CO 2 (pCO 2 ): air (ambient CO 2 ) and the pCO 2 predicted by the end of the 21st century (700 µatm, high CO 2 ), on photosynthesis, photosynthetic pigments and photoprotection in calcifying (Ellisolandia elongata and Padina pavonica) and non-calcifying (Cystoseira tamariscifolia) macroalgae. The calcifying P. pavonica showed higher net photosynthesis under high CO 2 than under ambient CO 2 conditions, whereas the opposite occurred in C. tamariscifolia. Both brown algae (P. pavonica and C. tamariscifolia) showed activation of non-photochemical quenching mechanisms under high CO 2 conditions. However, in P. pavonica the phenol content was reduced after CO 2 enrichment. In contrast to phenols, in E. elongata other photoprotectors such as zeaxanthin and palythine (mycosporine-like amino acid) tended to increase in the high CO 2 treatment. The different responses of these species to elevated pCO 2 may be due to anatomical and physiological differences and could represent a shift in their relative dominance as key species in the face of ocean acidification (OA). More in situ studies could be carried out to evaluate how macroalgae will respond to increases in pCO 2 in a future OA scenario. The in situ incubator system proposed in this work may contribute towards increasing this knowledge.

Photosynthesis and calcification in the articulated coralline alga Ellisolandia elongata (Corallinales, Rhodophyta) from intertidal rock pools

“…Photoinhibition was observed at high irradiances, as has previously been reported in low light acclimated algae (Kain, 1987;Sagert et al, 1997;Kühl et al, 2001;Roberts et al, 2002;Martin et al, 2013b). Recently, photoinhibition was also observed in E. elongata under rapid light curves (RLCs) (Korbee et al, 2014) giving further evidence for E. elongata being a 'shade plant', which Häder et al (2003) postulated was characteristic of all geniculate coralline algal species. Coralline algae have been reported to exhibit dynamic photoinhibition strategies which probably enable the algae to tolerate high irradiance levels rather than undergoing photodamage (Burdett et al, 2014).…”

Coralline Algae in a Changing Mediterranean Sea: How Can We Predict Their Future, if We Do Not Know Their Present?

“…More recent studies investigated populations of Ellisolandia elongata from the Alboran Sea, highlighting several metabolic features that make this alga well-adapted to withstand the environmental stresses typical of its interidal habitat (Celis-Plá et al, 2014;Figueroa et al, 2014a;Korbee et al, 2014;Parages et al, 2014;Stengel et al, 2014). This alga is able to improve its photoprotective capacity by regulating its content in mycosporine-like aminoacids (MAAs, compounds well-known for their photoprotective role in numerous algae) in response to environmental conditions (Celis-Plá et al, 2014;Korbee et al, 2014).…”

“…More recent studies investigated populations of Ellisolandia elongata from the Alboran Sea, highlighting several metabolic features that make this alga well-adapted to withstand the environmental stresses typical of its interidal habitat (Celis-Plá et al, 2014;Figueroa et al, 2014a;Korbee et al, 2014;Parages et al, 2014;Stengel et al, 2014). This alga is able to improve its photoprotective capacity by regulating its content in mycosporine-like aminoacids (MAAs, compounds well-known for their photoprotective role in numerous algae) in response to environmental conditions (Celis-Plá et al, 2014;Korbee et al, 2014). Stengel et al (2014) demonstrated a reduction in the effective photosystem II quantum efficiency in the central hours of the day, and showed that the highest phycocyanin content occurred in the evening; Parages et al (2014) performed proteomic studies on the same samples and concluded that mitogen-activated protein kinase (MAPK)-like proteins are involved in the response of this species to environmental stress.…”

Increased CO2 Relevant to Future Ocean Acidification Alleviates the Sensitivity of a Red Macroalgae to Solar Ultraviolet Irradiance by Modulating the Synergy Between Photosystems II and I

“…( Suárez-Álvarez et al, 2012 ), and Ellisolandia sp. ( Korbee et al, 2014 ). In addition, the increased DIC would also down-regulate the CO 2 -concentrating mechanisms (CCMs), which utilize HCO 3 − to compensate for the limitation of CO 2 in seawater and maintain high intracellular CO 2 levels for photosynthesis and growth of the macroalgae (e.g., a green algae Ulva prolifera in Xu and Gao, 2012 , and a red algae Pyropia yezoensis in Li et al, 2016 ).…”