Crystallinity and microchemistry of Nassarius reticulatus (Caenogastropoda) statoliths: towards their structure stability and homogeneity.
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.
Biology Department & CESAM, University of Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro, Portugal. Electronic address: susana.oliveira@ua.pt.
Susana
S
Galante-Oliveira
Biology Department & CESAM, University of Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro, Portugal.
Raquel
R
Marçal
Unit of Science and Mineral Technology, National Laboratory of Energy and Geology (LNEG), Rua da Amieira, Apart. 1089, 4466-901 S. Mamede de Infesta, Portugal.
Fernanda
F
Guimarães
Department of Physics & I3N, University of Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro, Portugal.
Jorge
J
Soares
Department of Physics & I3N, University of Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro, Portugal.
José Carlos
JC
Lopes
Laboratory of Applied Physiology, Department of Aquatic Production, Institute of Biomedical Sciences Abel Salazar (ICBAS), University of Porto, Rua de Jorge Viterbo Ferreira 228, 4050-313 Porto, Portugal.
Jorge
J
Machado
Biology Department & CESAM, University of Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro, Portugal.
Carlos
C
Barroso
D000818:Animals; D001639:Bicarbonates / Q000032:analysis*; D002119:Calcium Carbonate / Q000032:analysis*; D004577:Electron Probe Microanalysis; D049851:Gastropoda; D010037:Otolithic Membrane / Q000737:chemistry* / Q000648:ultrastructure*; D013059:Spectrum Analysis, Raman; D013324:Strontium / Q000032:analysis; D013696:Temperature; D014961:X-Ray Diffraction
D001639:Bicarbonates; D002119:Calcium Carbonate; D013324:Strontium
Electron microprobe analysis; Gastropoda; Micro Raman spectroscopy; Microchemistry; Statolith; Statoparticles