Anthropogenic CO2 emissions are causing ocean acidification (OA), which affects calcifying organisms. Recent studies have shown that Padina pavonica investigated along a natural pCO2 gradient seems to acclimate to OA by reducing calcified structures and changing mineralogy from aragonite to calcium sulphate salts. The aim of the present study was to study the potential for acclimation of P. pavonica to OA along the same gradient and in aquaria under controlled conditions. P. pavonica was cross-transplanted for one week from a normal pH site (median value: pHTS = 8.1; pCO2 = 361 μatm) to a low pH site (median value: pHTS = 7.4; pCO2 = 1025 μatm) and vice versa. Results showed that this calcifying alga did survive under acute environmental pHTS changes but its calcification was significantly reduced. P. pavonica decalcified and changed mineralogy at pHTS = 7.4, but once brought back at pHTS = 8.1 it partially recovered the aragonite loss while preserving the calcium sulphate minerals that formed under low pHTS. These results suggest that P. pavonica could be used as a bio-indicator for monitoring OA, as well as localized anthropogenic acidity fluctuations.
Iluz D., Fermani S., Ramot M., Reggi M., Caroselli E., Prada F., Dubinsky Z., Goffredo S. & Falini G., in press. Calcifying response and recovery potential of the brown alga Padina pavonica under ocean acidification. ACS Earth and Space Chemistry. Article (subscription required).
