HighGrass - High-CO2 effects on seagrass photosynthetic ecophysiology
Summary
The atmospheric concentration of CO2 has been steeply increasing since the beginning of the industrial era. The oceans are responsible for taking up around 25% of the anthropogenic CO2 emitted into the atmosphere, but in this process the seawater chemistry is being altered, with the increase of total dissolved inorganic carbon (Ci) and the decrease of pH. At present, very little is known on the potential effects that these changes may have on seagrass biology and ecology, despite the fact that these plants are among the world's most productive marine ecosystems, with a very high ecological and economical importance (Costanza et al. 1997). A major impact is likely to occur at the photosynthetic carbon acquisition level. On the current state of the art, major uncertainties still persist concerning the operation of the fundamental processes of light harvesting and carbon acquisition in seagrasses. Much of these gaps are related to the fact that, although seagrasses are angiosperms, some of the physiological mechanisms and pathways of light harvesting and carbon acquisition are not identical to those found in their terrestrial counterparts, neither to those used by macroalgae inhabiting similar aquatic environments. Therefore, a comprehensive understanding of the operation of these mechanisms is a pre-requisite for further research aiming to predict the effects of a high-CO2 environment on seagrass physiology, productivity, distribution and ecosystem function. While it is commonly assumed that seagrass photosynthetic rates will respond positively to a high-CO2 scenario (Hellblom et al. 2001), the few published studies on this subject are not consensual, showing diverse responses and lacking physiological insights and explanations for the observed results. On the other hand, studies conducted in natural CO2 vents revealed that seagrasses have adapted to live under permanently high CO2 levels (Hall-Spencer et al. 2008) and are able to exploit CO2 of volcanic origin (Vizzini et al. 2010). Nevertheless, little information is still available on the effects of more diffuse and stable release of hydrothermal CO2 on seagrass productivity.
The first step in our research will be to solve critical knowledge gaps regarding the operation of the fundamental physiological processes of light harvesting and carbon acquisition in seagrasses. The next step will be to determine, in controlled mesocosm conditions, the short and long-term effects of high CO2 exposure on the operation of these two processes. Finally, we shall investigate how seagrasses growing in the vicinity of natural CO2 venting sites have adapted to long-lasting high CO2 conditions, under both high- and low-light regimes. To address this sequential set of objectives, we shall use an innovative combination of ecophysiological tools, coupled to genomics and proteomics techniques in a multilevel approach, from genes to the whole-plant level.
SZN role
Participant Institution for the genetic characterization of seagrass species in situ and in mesocosms experiment and for assessment of gene expression in situ and controlled conditions.
Partners
University of Algarve, Portugal; Stazione Zoologica Anton Dohrn, Italy; University of Palermo, Italy; University of Calabria, Italy
Project lifetime
2013-2014
P. I.
Gabriele Procaccini
Project coordinator: Joao Silva (University of Algarve, Portugal)
Funding Institution
Ministerio da Ciencia, Tecnologia e Ensino Superior - Portugal
