Zheng Y, Giordano M, Gao K

Photochemical responses of the diatom Skeletonema costatum grown under elevated CO₂ concentrations to short-term changes in pH

Most studies on ocean acidification have concerned the acclimation of organisms to different pCO₂ concentrations. To test whether such acclimation modifies responses to pH, Zheng and co-workers investigated the impact of abrupt changes in pH on cells of the diatom Skeletonema costatum acclimated to 390 and 1000 µatm CO₂. They found that cells acclimated to high CO₂ levels had a higher photosynthetic efficiency than cells acclimated to low pCO₂. An abrupt pH decrease from 8.2 to 7.6 did not affect the photosynthetic quantum yield of cells cultured at high CO₂ concentrations, whereas quantum yield decreased dramatically in cells grown at low CO₂. Acclimation to high CO₂ levels thus mitigates the effects of short-term acidification on the photophysiology of S. costatum.

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