Structural and mechanical properties of staghorn coral (Acropora cervicornis) CaCO₃ aragonite skeletons, cleaned by chemical bleaching and biological processes

ABSTRACT

Coral reefs provide habitat for most oceanic life forms, however, they are declining worldwide due to pollution, increased ocean temperature, diseases and other factors. In this paper, structural and mechanical properties of endangered coral (Acropora cervicornis) skeletons cleaned by chemical bleaching and biological processes were studied. The structure of CaCO₃ aragonite skeleton is porous and very complex and affects the deformation behaviour of coral skeletons. The average compressive strength was equal to 9.5 ± 2.3 MPa and 14.5 ± 6.4 MPa, while Vickers hardness was measured to be equal to 3.67 ± 0.33 GPa and 3.65 ± 0.24 GPa for the chemically bleached and biologically cleaned skeletons, respectively, thus showing similar values regardless of the cleaning techniques. The results are important for understanding the fundamental relationship between the coral skeleton’s microstructure and mechanical behaviour.

KEYWORDS:

• Mechanical properties
• microstructure
• porous materials
• CaCO₃ aragonite
• coral skeleton

Acknowledgements

Bridget Masa’s and Zachary Shepard’s help with performing mechanical tests of CaCO₃ aragonite coral skeletons is greatly appreciated. This research was supported in part by NSF MRI award #133775. The GE Phoenix Nanotom-M™ X-ray CT was acquired through NSF Award # 0959511. Initial harvest of staghorn coral fragments to establish the NSU coral nursery was authorised under Florida Fish and Wildlife Conservation Commission Special Activity License # SAL-10-1086-SCRP.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by National Science Foundation: Grant Numbers 0959511 and 133775.