Potential resilience to ocean acidification of benthic foraminifers living in Posidonia oceanica meadows: the case of the shallow venting site of Panarea.

This research shows the results regarding the response to acidic condition of the sediment and Posidonia foraminiferal assemblages collected around the Panarea Island. The AeolianArchipelago represents a natural laboratory and a much-promising study site for multidisciplinarymarine research (carbon capture and storage, geochemistry of hydrothermal fluids and ocean acidification vs. benthic and pelagic organisms). The variability and the complexity of the interactionof the ecological factors characterizing extreme environments such as shallow hydrothermal ventsdid not allow us to carry out a real pattern of biota responses in situ, differently from those observedunder controlled laboratory conditions. However, the study provides new insights into foraminiferalresponse to increasing ocean acidification (OA) in terms of biodiversity, faunal density, specificcomposition of the assemblages and morphological variations of the shells. The study highlights howthe foraminiferal response to different pH conditions can change depending on different environmental conditions and microhabitats (sediments, Posidonia leaves and rhizomes). Indeed, mineralsediments were more impacted by acidification, whereas Posidonia microhabitats, thanks to theirbuffer effect, can offer "refugia" and more mitigated acidic environment. At species level, rosalinidsand agglutinated group represent the most abundant taxa showing the most specific resilience andcapability to face acidic conditions.