Distribution of sea urchins living near shallow water CO(2) vents is dependent upon species acid-base and ion-regulatory abilities.

o reduce the negative effect of climate change on Biodiversity, the use of geological CO(2) sequestration has been proposed; however leakage from underwater storages may represent a risk to marine life. As extracellular homeostasis is important in determining species' ability to cope with elevated CO(2), we investigated the acid-base and ion regulatory responses, as well as the density, of sea urchins living around CO(2) vents at Vulcano, Italy. We conducted in situ transplantation and field-based laboratory exposures to different pCO(2)/pH regimes. Our results confirm that sea urchins have some ability to regulate their extracellular fluid under elevated pCO(2). Furthermore, we show that even in closely-related taxa divergent physiological capabilities underlie differences in taxa distribution around the CO(2) vent. It is concluded that species distribution under the sort of elevated CO(2) conditions occurring with leakages from geological storages and future ocean acidification scenarios, may partly be determined by quite subtle physiological differentiation.