title: Biomineral shell formation under ocean acidification: a shift from order to chaos.
abstract: Biomineral production in marine organisms employs transient phases of amorphous calcium carbonate (ACC) in the construction of crystalline shells. Increasing seawater pCO2 leads to ocean acidification (OA) with a reduction in oceanic carbonate concentration which could have a negative impact on shell formation and therefore survival. We demonstrate significant changes in the hydrated and dehydrated forms of ACC in the aragonite and calcite layers of Mytilus edulis shells cultured under acidification conditions (1000 μatm pCO2) compared to present day conditions (380 μatm pCO2). In OA conditions, Mytilus edulis has more ACC at crystalisation sites. Here, we use the high-spatial resolution of synchrotron X-ray Photo Emission Electron Microscopy (XPEEM) combined with X-ray Absorption Spectroscopy (XAS) to investigate the influence of OA on the ACC formation in the shells of adult Mytilus edulis. Electron Backscatter Diffraction (EBSD) confirms that OA reduces crystallographic control of shell formation. The results demonstrate that OA induces more ACC formation and less crystallographic control in mussels suggesting that ACC is used as a repair mechanism to combat shell damage under OA. However, the resultant reduced crystallographic control in mussels raises concerns for shell protective function under predation and changing environments.
authors.affiliation: School of Geographical and Earth Sciences, University of Glasgow, Glasgow, G12 8QQ, UK.
authors.forename: Susan C
authors.initials: SC
authors.lastname: Fitzer
authors.affiliation: School of Geographical and Earth Sciences, University of Glasgow, Glasgow, G12 8QQ, UK.
authors.forename: Peter
authors.initials: P
authors.lastname: Chung
authors.affiliation: Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE, UK.
authors.forename: Francesco
authors.initials: F
authors.lastname: Maccherozzi
authors.affiliation: Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE, UK.
authors.forename: Sarnjeet S
authors.initials: SS
authors.lastname: Dhesi
authors.affiliation: School of Geographical and Earth Sciences, University of Glasgow, Glasgow, G12 8QQ, UK.
authors.forename: Nicholas A
authors.initials: NA
authors.lastname: Kamenos
authors.affiliation: School of Geographical and Earth Sciences, University of Glasgow, Glasgow, G12 8QQ, UK.
authors.forename: Vernon R
authors.initials: VR
authors.lastname: Phoenix
authors.affiliation: School of Geographical and Earth Sciences, University of Glasgow, Glasgow, G12 8QQ, UK.
authors.forename: Maggie
authors.initials: M
authors.lastname: Cusack
mesh_terms: D000143:Acids / Q000737:chemistry; D000818:Animals; D059001:Aquatic Organisms / Q000737:chemistry / Q000378:metabolism*; D002119:Calcium Carbonate / Q000737:chemistry / Q000378:metabolism*; D002245:Carbon Dioxide / Q000737:chemistry / Q000378:metabolism; D049880:Mytilus edulis / Q000737:chemistry / Q000378:metabolism; D009792:Oceans and Seas; D056928:X-Ray Absorption Spectroscopy
chemical_list: D000143:Acids; D002245:Carbon Dioxide; D002119:Calcium Carbonate