TY - JOUR
T1 - Skeletal growth, ultrastructure and composition of the azooxanthellate scleractinian coral Balanophyllia regia
AU - Brahmi, C.
AU - Meibom, A.
AU - Smith, D. C.
AU - Stolarski, J.
AU - Auzoux-Bordenave, S.
AU - Nouet, J.
AU - Doumenc, D.
AU - Djediat, C.
AU - Domart-Coulon, I.
N1 - Funding Information:
work was supported in part by the Agence National de la Recherche and by the Programme PluriFormation PPF ‘Biomineralization’ of the MNHN funded by the Ministère délégué à l’Enseignement supérieur et à la Recherche. The National NanoSIMS facility at the Muséum National d’Histoire Naturelle was established by funds from the CNRS, Région ˆle de France, Ministère délégué à l’Enseignement supérieur et àla Recherche and the Muséum itself.
PY - 2010/2
Y1 - 2010/2
N2 - The biomineralization process and skeletal growth dynamics of azooxanthellate corals are poorly known. Here, the growth rate of the shallow-water dendrophyllid scleractinian coral Balanophyllia regia was evaluated with calcein-labeling experiments that showed higher lateral than vertical extension. The structure, mineralogy and trace element composition of the skeleton were characterized at high spatial resolution. The epitheca and basal floor had the same ultrastructural organization as septa, indicating a common biological control over their formation. In all of these aragonitic skeletal structures, two main ultrastructural components were present: "centers of calcification" (COC) also called rapid accretion deposits (RAD) and "fibers" (thickening deposits, TD). Heterogeneity in the trace element composition, i. e., the Sr/Ca and Mg/Ca ratios, was correlated with the ultrastructural organization: magnesium was enriched by a factor three in the rapid accretion deposits compared with the thickening deposits. At the interface with the skeleton, the skeletogenic tissue (calicoblastic epithelium) was characterized by heterogeneity of cell types, with chromophile cells distributed in clusters regularly spaced between calicoblasts. Cytoplasmic extensions at the apical surface of the calicoblastic epithelium created a three-dimensional organization that could be related to the skeletal surface microarchitecture. Combined measurements of growth rate and skeletal ultrastructural increments suggest that azooxanthellate shallow-water corals produce well-defined daily growth steps.
AB - The biomineralization process and skeletal growth dynamics of azooxanthellate corals are poorly known. Here, the growth rate of the shallow-water dendrophyllid scleractinian coral Balanophyllia regia was evaluated with calcein-labeling experiments that showed higher lateral than vertical extension. The structure, mineralogy and trace element composition of the skeleton were characterized at high spatial resolution. The epitheca and basal floor had the same ultrastructural organization as septa, indicating a common biological control over their formation. In all of these aragonitic skeletal structures, two main ultrastructural components were present: "centers of calcification" (COC) also called rapid accretion deposits (RAD) and "fibers" (thickening deposits, TD). Heterogeneity in the trace element composition, i. e., the Sr/Ca and Mg/Ca ratios, was correlated with the ultrastructural organization: magnesium was enriched by a factor three in the rapid accretion deposits compared with the thickening deposits. At the interface with the skeleton, the skeletogenic tissue (calicoblastic epithelium) was characterized by heterogeneity of cell types, with chromophile cells distributed in clusters regularly spaced between calicoblasts. Cytoplasmic extensions at the apical surface of the calicoblastic epithelium created a three-dimensional organization that could be related to the skeletal surface microarchitecture. Combined measurements of growth rate and skeletal ultrastructural increments suggest that azooxanthellate shallow-water corals produce well-defined daily growth steps.
KW - Azooxanthellate
KW - Biomineralization
KW - Calcein
KW - Calicoblastic epithelium
KW - Chromophile cells
KW - Growth rate
KW - Scleractinia
UR - http://www.scopus.com/inward/record.url?scp=76149129696&partnerID=8YFLogxK
U2 - 10.1007/s00338-009-0557-x
DO - 10.1007/s00338-009-0557-x
M3 - Article
AN - SCOPUS:76149129696
VL - 29
SP - 175
EP - 189
JO - Coral Reefs
JF - Coral Reefs
SN - 0722-4028
IS - 1
ER -