Modification of Ca isotope and trace metal composition of the major matrices involved in shell formation of Mytilus edulis

Abstract

[1] In this study we present the first combined investigation into the composition of the major matrices involved in calcification processes (surrounding water, extrapallial fluid, aragonite, and calcite) of Mytilus edulis with respect to their calcium isotope (d 44/40 Ca) and elemental compositions (Sr/Ca and Mg/Ca). Our aim was to examine the suitability of Mytilus edulis as a proxy archive and to contribute to the understanding of the process of biomineralization. Mytilus edulis specimens were live collected from the Schwentine Estuary, Kiel Fjord, and North Sea (Sylt). d 44/40 Ca was determined by thermal ionization mass spectrometry (TIMS) accompanied by measurements of Mg/Ca and Sr/Ca using inductively coupled plasma-optical emission spectroscopy (ICP-OES). The elemental and isotopic compositions of the investigated matrices showed systematic offsets. The carbonates are strongly depleted in their magnesium and strontium concentrations and fractionated toward lighter calcium isotope compositions relative to the surrounding Schwentine Estuary water. The opposite is observed for the extrapallial fluid (EPF). Our findings extend the results of previous studies reporting a strong biological control and the interaction of different environmental conditions influencing biomineralization. Future studies should focus on the temporal development of the interrelation between the different matrices.

Controls on calcium isotope fractionation in cultured planktic foraminifera, Globigerinoides ruber and Globigerinella siphonifera

“…It follows that the vacuoles, modified in their chemistry by the organism, are eventually exocytosed into the site of biomineralization, which has exchange with seawater (Erez, 2003). Data on brachiopods (Steuber and Buhl, 2006;Farkaš et al, 2007), blue mussels (Heinemann et al, 2008) and planktic foraminifera (this study) plot close to the inorganic regression line (Tang et al, 2008b), with a small positive offset in D Sr . It must be noted that D 44/40 Ca and D Sr of brachiopods and planktic foraminifera are reported relative to seawater, whereas those of the blue mussel, Mytilus edulis, are reported relative to the extrapallial fluid.…”

“…Enrichment of Sr/Ca in the coccolith calcite compared to inorganic calcite has been explained using a simple conceptual model based on the channel-mediated transport of Ca and Sr to the coccolith vesicle (Langer et al, , 2009. In addition, the positive correlation between D Sr and calcification rates in coccolithophores Heinemann et al, 2008), average planktic foraminifer (white diamond; this study) and coccolithophore Emiliania huxleyi (gray triangle; Langer et al, 2006Langer et al, , 2007. (Stoll and Schrag, 2000) has been explained by a ratedependent discrimination between the biological transport of Sr and Ca ions (Rickaby et al, 2002).…”

Constraining calcium isotope fractionation (δ44/40Ca) in modern and fossil scleractinian coral skeleton

“…Calcium isotopic fractionation (δ 44/40 Ca) was studied in various marine organisms including foraminifera (Gussone et al, 2003(Gussone et al, , 2009(Gussone et al, , 2010Griffith et al, 2008;Hippler et al, 2009), coccoliths (Gussone et al, 2007;Langer et al, 2007), rudists (Immenhauser et al, 2005), brachiopods (von Allmen et al, 2010), dinoflagellate (Gussone et al, 2010) and bivalves (Heinemann et al, 2008). These studies revealed a significant relationship between calcium isotopic fractionation and temperature (Nägler et al, 2000;Gussone et al, 2003), mineralogy (Gussone et al, 2005) and inter-generic differences (Gussone et al, 2006(Gussone et al, , 2007.…”

Identifying vital effects in <i>Halimeda</i> algae with Ca isotopes

“…The blue mussel, Mytilus edulis, demonstrates the significance of these effects by precipitating its skeleton from an extrapallial fluid that has higher δ 44 / 40 Ca than the surrounding seawater (Heinemann et al, 2008), producing a difference in δ 44 / 40 Ca between its calcitic and aragonitic skeletal components of only 0.25 ‰, rather than the expected 0.9 ‰ for an inorganic process. Transport effects and Rayleigh distillation have also been implicated in coccolith calcification and coral skeletal growth (Böhm et al, 2006).…”