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Crystallinity and microchemistry of Nassarius reticulatus (Caenogastropoda) statoliths : towards their structure stability and homogeneity
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Resumo(s)
Gastropod statoliths are spherical biocarbonates formed during their lifespan. The stability and homogeneity of these structures’ mineral matrix was
characterised along their radiuses, using Nassarius reticulatus as a model. Generally, they were proved to be bimineralic. Two of the three CaCO3 crystalline
polymorphs occurring in biocarbonates – aragonite and calcite – coexist along statolith radiuses, aragonite being unequivocally the most abundant phase. The
presence of a diffuse organic matrix was also perceived by the detection of a weak Raman band between 2800 and 3000 cm-1 consistently observed along
radiuses. Beyond the apparent stability and homogeneity, different crystalline orientations were disclosed by Raman spectroscopy. A change in the intensity
pattern of the features related to the lattice and bending modes of aragonite between different radiuses give new insights for a possible spherulitic-like
growth of these structures. As expected from the relative homogeneity of both mineral and organic signals, there was no pattern on the distribution of Ca, O,
Na and S along radiuses. However, a higher concentration of Sr occurs in growth rings (known as winter tags), corroborating the already described negative
correlation between the concentration of this element in statoliths and temperature. Despite the apparent stability and homogeneity of the matrix during its
lifespan, the periodic distribution of Sr potentially influences a dissimilar incorporation of trace elements in increments and growth rings. Since gastropod
statolith elemental fingerprinting was recently suggested as a new tool to monitor marine environmental changes, the pressing need for further studies on the
incorporation of traces in these structures is highlighted.
Descrição
Palavras-chave
Cristalinidade Microquímica Gastrópodes Espectroscopia Raman
Contexto Educativo
Citação
Galante-Oliveira, Susana... [et al.] - Crystallinity and microchemistry of Nassarius reticulatus (Caenogastropoda) statoliths : towards their structure stability and homogeneity. In: Journal of Structural Biology, Vol. 186, Issue 2 (May 2014), p. 292-301