Optical Observations and Geochemical Data in Deep-Sea Hexa- and Octo-Coralla Specimens

Abstract

Coral skeletons are built by Ca-carbonate (calcite or aragonite) crystals that exhibit distinct morphological patterns and specific spatial arrangements that constitute skeletal microstructures. Additionally, the long-standing recognition that distinct coral species growing in similar conditions are able to record environmental changes with species-specific responses provides convincing evidence that, beyond the thermodynamic rules for chemical precipitation, a biological influence is at work during the crystallization process. Through several series of comparative structural and geochemical (elemental and isotopic) data, this paper aims to firmly establish the specific properties of the distinct major taxonomic units that are commonly gathered as deep-water "corals" in current literature. Moreover, taking advantage of recent micrometric and infra-micrometric observations, attention is drawn to the remarkable similarity of the calcareous material observed at the nanoscale. These observations suggest a common biomineralization model in which mineralogical criteria are not the leading factors for the interpretation of the geochemical measurements.

Constraining past environmental changes of cold‐water coral mounds with geochemical proxies in corals and foraminifera

“…To date there are only a few studies that systematically evaluate the impact of seawater salinity or temperature on Na incorporation into cold-water Scleractinia. For example, the study by Rollion-Bard and Blamart (2015) suggests that changes in growth rate due to varying seawater temperature might control the incorporation of Na (Li and Mg) and the studies of Rollion-Bard et al (2017) and Schleinkofer et al (2019) imply that a temperature control on Na/Ca ratios might also exist in aragonitic marine species.…”

Visual Imaging of Benthic Carbonate-Mixed Factories in the Ross Sea Region Marine Protected Area, Antarctica

“…50% (>2300 ind., Figure 5) of the overall benthic community, with the bamboo coral P. delicatula and S. narconensis as main contributors (858 and 828 ind., respectively). Octocorals such as the Primnoisis contribute to the carbonate sediment by shedding calcified internodes post-mortem, which is made up of high-Mg calcite [97] together with the serpulids, as mentioned above.…”