Magnesium and sulphur in the calcite shells of two brachiopods, Terebratulina retusa and Novocrania anomala

Abstract

This study determines the distribution of magnesium and sulphur in the shells of two species of brachiopod from the same environment to highlight environmental and biological influences on shell composition. In Terebratulina retusa there are differences in magnesium concentration between the primary layer and the outer and inner regions of the secondary layer. In contrast, Novocrania anomala has a shell composed of high magnesium calcite and there is no significant difference in magnesium concentration between the primary and the secondary shell layers. Sulphur provides an indication of the distribution of sulphated organic matrix within the shells of T. retusa and N. anomala. In T. retusa the distribution of magnesium and sulphur correlates across the shell; however, there is no evidence for a relationship between magnesium and sulphur distribution in N. anomala. The relationship between magnesium and sulphur in T. retusa indicates that a proportion of the magnesium content of the shell is associated with the sulphated fraction of the organic matrix. In these two species of brachiopod, from the same environment, magnesium and organic concentration and distribution are very different, emphasizing the importance of fully understanding the factors that control biomineral composition before the application of these biominerals to environmental studies

Biogenic and toxic elements in feathers, eggs, and excreta of Gentoo penguin (Pygoscelis papua ellsworthii) in the Antarctic

“…No data about feathers were found. However, England et al (2007) reported that a proportion of Mg content is associated with the sulfated fraction of the organic matrix in the shell of Terebratulina retusa.…”

Raman spectroscopy of synthetic, geological and biological vaterite: a Raman spectroscopic study

“…This may also explain the fact that synthetic vaterite reaches Mg saturation roughly at around 2000 ppm [45] (Materials and methods), while much higher values are observed in biominerals. [46,47] …”

Multiscale structure of calcite fibres of the shell of the brachiopod Terebratulina retusa

“…The Linguliformea have shells of calcium phosphate while the Craniiformea and Rhynchonelliformea have calcite shells. Craniiformean brachiopods have high Mg-calcite (Jope, 1965) semi-nacre shells (England et al, 2007b;Williams, 1970;Williams and Wright, 1970;Williams et al, 1999) and rhynchonelliform brachiopods have shells comprising low Mg-calcite fibres (Cusack et al, 1997;Cusack and Williams, 2007;England et al, 2007b;Jope, 1965). Terebratulina retusa typifies this sub-phylum with an outer (primary) shell layer that has acicular calcite underlain by the secondary layer of calcite fibres (Fig.…”