title: A Novel μCT Analysis Reveals Different Responses of Bioerosion and Secondary Accretion to Environmental Variability.
abstract: Corals build reefs through accretion of calcium carbonate (CaCO3) skeletons, but net reef growth also depends on bioerosion by grazers and borers and on secondary calcification by crustose coralline algae and other calcifying invertebrates. However, traditional field methods for quantifying secondary accretion and bioerosion confound both processes, do not measure them on the same time-scale, or are restricted to 2D methods. In a prior study, we compared multiple environmental drivers of net erosion using pre- and post-deployment micro-computed tomography scans (μCT; calculated as the % change in volume of experimental CaCO3 blocks) and found a shift from net accretion to net erosion with increasing ocean acidity. Here, we present a novel μCT method and detail a procedure that aligns and digitally subtracts pre- and post-deployment μCT scans and measures the simultaneous response of secondary accretion and bioerosion on blocks exposed to the same environmental variation over the same time-scale. We tested our method on a dataset from a prior study and show that it can be used to uncover information previously unattainable using traditional methods. We demonstrated that secondary accretion and bioerosion are driven by different environmental parameters, bioerosion is more sensitive to ocean acidity than secondary accretion, and net erosion is driven more by changes in bioerosion than secondary accretion.
authors.affiliation: Department of Ecology and Evolutionary Biology, University of California at Irvine, Irvine, California, United States of America.|Hawai'i Institute of Marine Biology, University of Hawai'i at Mānoa, Kāne'ohe, Hawai'i, United States of America.
authors.forename: Nyssa J
authors.initials: NJ
authors.lastname: Silbiger
authors.affiliation: School of Life Sciences, Joseph Banks Laboratories, University of Lincoln, Lincoln, United Kingdom.
authors.forename: Òscar
authors.initials: Ò
authors.lastname: Guadayol
authors.affiliation: Hawai'i Institute of Marine Biology, University of Hawai'i at Mānoa, Kāne'ohe, Hawai'i, United States of America.
authors.forename: Florence I M
authors.initials: FI
authors.lastname: Thomas
authors.affiliation: Hawai'i Institute of Marine Biology, University of Hawai'i at Mānoa, Kāne'ohe, Hawai'i, United States of America.
authors.forename: Megan J
authors.initials: MJ
authors.lastname: Donahue
mesh_terms: D000818:Animals; D037421:Anthozoa / Q000254:growth & development*; D002113:Calcification, Physiologic / Q000502:physiology; D002119:Calcium Carbonate; D057894:Coral Reefs; D008962:Models, Theoretical; D012623:Seawater; D055114:X-Ray Microtomography
chemical_list: D002119:Calcium Carbonate