title: Comparison of Mediterranean Pteropod Shell Biometrics and Ultrastructure from Historical (1910 and 1921) and Present Day (2012) Samples Provides Baseline for Monitoring Effects of Global Change.
abstract: Anthropogenic carbon perturbation has caused decreases in seawater pH and increases in global temperatures since the start of the 20th century. The subsequent lowering of the saturation state of CaCO3 may make the secretion of skeletons more problematic for marine calcifiers. As organisms that precipitate thin aragonite shells, thecosome pteropods have been identified as being particularly vulnerable to climate change effects. Coupled with their global distribution, this makes them ideal for use as sentinel organisms. Recent studies have highlighted shell dissolution as a potential indicator of ocean acidification; however, this metric is not applicable for monitoring pH changes in supersaturated basins. In this study, the novel approach of high resolution computed tomography (CT) scanning was used to produce quantitative 3-dimensional renderings pteropod shells to assess the potential of using this method to monitor small changes in shell biometrics that may be driven by climate change drivers. An ontogenetic analysis of the shells of Cavolinia inflexa and Styliola subula collected from the Mediterranean was used to identify suitable monitoring metrics. Modern samples were then compared to historical samples of the same species, collected during the Mediterranean leg of the Thor (1910) and Dana (1921) cruises to assess whether any empirical differences could be detected. Shell densities were calculated and scanning electron microscopy was used to compare the aragonite crystal morphology. pH for the collection years was hind-cast using temperature and salinity time series with atmospheric CO2 concentrations from ice core data. Historical samples of S. subula were thicker than S. subula shells of the same size from 2012 and C. inflexa shells collected in 1910 were significantly denser than those from 2012. These results provide a baseline for future work to develop monitoring techniques for climate change in the oceans using the novel approach of high-resolution CT scanning.
authors.affiliation: Sorbonne Universités, UPMC Univ Paris 06, CNRS-INSU, Laboratoire d'Océanographie de Villefranche, 181 chemin du Lazaret, Villefranche-sur-mer, France.|Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung, Bremerhaven, Germany.
authors.forename: Ella L
authors.identifier: 0000-0002-4303-2761
authors.initials: EL
authors.lastname: Howes
authors.affiliation: Université de Brest-UMR 6539 CNRS/UBO/IRD/Ifremer, Laboratoire des sciences de l'environnement marin-IUEM-Rue Dumont D'Urville-Plouzané, France.|Department of Atmospheric and Oceanic Sciences, Institute of the Environment and Sustainability, University of California, Los Angeles, CA, United States of America.
authors.forename: Robert A
authors.initials: RA
authors.lastname: Eagle
authors.affiliation: Sorbonne Universités, UPMC Univ Paris 06, CNRS-INSU, Laboratoire d'Océanographie de Villefranche, 181 chemin du Lazaret, Villefranche-sur-mer, France.|Institute for Sustainable Development and International Relations, Sciences Po, 27 rue Saint Guillaume, Paris, France.
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Gattuso
authors.affiliation: Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung, Bremerhaven, Germany.
authors.forename: Jelle
authors.initials: J
authors.lastname: Bijma
mesh_terms: D060105:Animal Shells / Q000378:metabolism / Q000648:ultrastructure*; D000818:Animals; D002119:Calcium Carbonate / Q000737:chemistry*; D002245:Carbon Dioxide / Q000737:chemistry* / Q000266:history; D057231:Climate Change / Q000266:history; D049851:Gastropoda / Q000033:anatomy & histology / Q000378:metabolism; D049673:History, 20th Century; D049674:History, 21st Century; D006863:Hydrogen-Ion Concentration; D008522:Mediterranean Sea; D008855:Microscopy, Electron, Scanning; D015233:Models, Statistical; D054712:Salinity; D012623:Seawater; D013696:Temperature
chemical_list: D002245:Carbon Dioxide; D002119:Calcium Carbonate