How does rising atmospheric CO2 affect marine organisms?

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CO2 Enrichment of a CAM Bromeliad
Ceusters, J., Borland, A.M., Londers, E., Verdoodt, V., Godts, C. and de Proft, M.P. 2008. Diel shifts in carboxylation pathway and metabolite dynamics in the CAM Bromeliad Aechmea 'Maya' in response to elevated CO2. Annals of Botany 102: 389-397.

What was done
The authors measured gas exchange and diel metabolite dynamics (e.g. malate, soluble sugars, starch) in the youngest fully-expanded leaves of well watered and fertilized CAM bromeliad Aechmea 'Maya' plants -- a spineless cultivar resulting from a cross between A. tessmannii and A. fasciata -- after exposure of half of the originally seven-month-old plants to 700 ppm CO2 for five additional months in one of two controlled-environment compartments of a greenhouse, the other of which compartments was maintained at the original atmospheric CO2 concentration of 380 ppm.

What was learned
Ceusters et al. report "there was a 60% increase in 24-hour carbon gain under elevated CO2 due to a stimulation of daytime C3 and C4 carboxylation." They also note that water use efficiency was two-fold higher during the night under elevated CO2 and three- to four-fold higher during the day.

What it means
The six scientists state that the great increase they observed in plant water use efficiency "could be a major physiological advantage to growth under elevated CO2 in this CAM bromeliad," and that this fact further suggests that CAM species should "be considered in an agronomic context as potential sources of biomass production on arid, marginal lands."

Reviewed 1 October 2008