The metabolic response of pteropods to acidification reflects natural CO2-exposure in oxygen minimum zones

Abstract. Shelled pteropods (Thecosomata) are a group of holoplanktonic mollusks that are believed to be especially sensitive to ocean acidification because their aragonitic shells are highly soluble. Despite this concern, there is very lit-tle known about the physiological response of these animals to conditions of elevated carbon dioxide. This study exam-ines the oxygen consumption and ammonia excretion of five pteropod species, collected from tropical regions of the Pa-cific Ocean, to elevated levels of carbon dioxide (0.10 %, 1000 ppm). Our results show that pteropods that naturally migrate into oxygen minimum zones, such as Hyalocylis stri-ata, Clio pyramidata, Cavolinia longirostris and Creseis vir-gula, were not affected by carbon dioxide at the levels and duration tested. Diacria quadridentata, which does not mi-grate, responds to high carbon dioxide conditions with re-duced oxygen consumption and ammonia excretion. This in-dicates that the natural chemical environment of individual species may influence their resilience to ocean acidification.