Preservation effects on the isotopic and elemental composition of skeletal structures in the deep-sea bamboo coral Lepidisis spp. (Isididae)

Abstract

Trace elements and stable isotopes (δ13C and δ15N) in deep-sea coral have been used as proxies to reconstruct past climate, and to investigate food web structure. However, there is a paucity of information regarding the effect of preservation on the chemical integrity of archived coral. In this study a live-caught colony of Bamboo coral (southern Australia), genus (Lepidisis), was sectioned into three pieces and stored for approximately one year to investigate the influence of preservation in ethanol and preservation in seawater, that mimics the early stages of fossilization, against a dry preserved control. Storage and preservation have no significant effect on the isotopic signature of Δ14C, bulk δ15N, δ15N and δ13C of individual amino acids, or C:N in the fibrillar protein matrix, with the only offset (~0.2‰) being observed in part of the δ13C record. In the high-magnesium calcite lattice Ba/Ca appears to be significantly different after storage in ethanol, whereas Δ14C, B/Ca, Mg/Ca, Sr/Ca, and U/Ca remain largely unaltered. Possible mechanisms responsible for these observed differences center around the decomposition, or contamination, by organics and we recommend further investigation, and caution when comparing samples with differing preservation histories.