title: Surviving rapid climate change in the deep sea during the Paleogene hyperthermals.
abstract: Predicting the impact of ongoing anthropogenic CO2 emissions on calcifying marine organisms is complex, owing to the synergy between direct changes (acidification) and indirect changes through climate change (e.g., warming, changes in ocean circulation, and deoxygenation). Laboratory experiments, particularly on longer-lived organisms, tend to be too short to reveal the potential of organisms to acclimatize, adapt, or evolve and usually do not incorporate multiple stressors. We studied two examples of rapid carbon release in the geological record, Eocene Thermal Maximum 2 (∼53.2 Ma) and the Paleocene Eocene Thermal Maximum (PETM, ∼55.5 Ma), the best analogs over the last 65 Ma for future ocean acidification related to high atmospheric CO2 levels. We use benthic foraminifers, which suffered severe extinction during the PETM, as a model group. Using synchrotron radiation X-ray tomographic microscopy, we reconstruct the calcification response of survivor species and find, contrary to expectations, that calcification significantly increased during the PETM. In contrast, there was no significant response to the smaller Eocene Thermal Maximum 2, which was associated with a minor change in diversity only. These observations suggest that there is a response threshold for extinction and calcification response, while highlighting the utility of the geological record in helping constrain the sensitivity of biotic response to environmental change.
authors.affiliation: Department of Earth Sciences, University of Bristol, Bristol BS8 1RJ, United Kingdom. l.c.foster@bristol.ac.uk
authors.forename: Laura C
authors.initials: LC
authors.lastname: Foster
authors.forename: Daniela N
authors.initials: DN
authors.lastname: Schmidt
authors.forename: Ellen
authors.initials: E
authors.lastname: Thomas
authors.forename: Sandra
authors.initials: S
authors.lastname: Arndt
authors.forename: Andy
authors.initials: A
authors.lastname: Ridgwell
mesh_terms: D000220:Adaptation, Biological / Q000502:physiology*; D001272:Atmosphere / Q000032:analysis*; D002113:Calcification, Physiologic / Q000502:physiology*; D002119:Calcium Carbonate / Q000032:analysis; D002245:Carbon Dioxide / Q000032:analysis*; D057231:Climate Change; D056908:Foraminifera / Q000737:chemistry* / Q000502:physiology; D049690:History, Ancient; D009792:Oceans and Seas; D017356:Synchrotrons; D014056:Tomography, X-Ray
chemical_list: D002245:Carbon Dioxide; D002119:Calcium Carbonate
keywords: ecosystem stress response; greenhouse gases; marine calcifiers