Field CO2 enrichment by submarine vents unravels Zostera noltii response to ocean acidification

Under future climate change, seagrasses may benefit from the effect of ocean acidification, although their response may be species-specific and may also depend on several ecological factors. Using a field manipulative approach, this study investigated the morphology and physiology of the seagrass Zostera noltii under the effect of increased CO2 concentrations, taking advantage of the presence of natural shallow submarine CO2. Comparisons between transplanted plants from control pH sites to low pH site with translocated control pH plants allowed investigating the short-term acidification effect. Moreover, an observative approach was used to assess the long- term acidification by comparing untouched plants from control pH with the low pH site. The photosynthetic pigments were increased under short-term and long-term acidification. Furthermore, the above-ground morphology of the seagrass may be improved by the short-term acidification, although these differences were no more evident on the long-term acidification. Therefore, Z. noltii could respond positively to the low pH conditions that will occur in the future, as the observed rapid plasticity response may lead to an initial acclimation.