Coral reefs, essential to marine ecosystems, rely on the structural integrity of their aragonite-based skeletons for survival. Yet, there is a pronounced discrepancy in the mechanical strength between single-crystal aragonite and whole coral structures, which remains inadequately explained. This study uses molecular dynamics (MD) simulations to deepen our understanding of coral mechanics by examining inter-crystal and crystal-protein interactions, which may hold the key to coral resilience under environmental stresses.

Our work begins with the refinement of interatomic potentials to more accurately model aragonite’s stiffness and strength properties. Adjustments to parameters ensure a closer fit to experimental stiffness values. These improvements allow us to simulate conditions that mirror natural coral environments more closely, with an emphasis on the twin interfaces and boundary misorientations that occur between rotated aragonite crystals.

A key focus of this study is the integration of protein interfaces, specifically the introduction of coral acid-rich proteins (CARPs), such as Lustrin A, to investigate their role in coral structure. Using existing force fields, protein structures are equilibrated and relaxed through steered MD before interacting with aragonite. Results indicate that protein-crystal interactions provide a measurable change in resilience and stiffness compared to single crystals, suggesting that proteins modulate the structural integrity of coral. This insight highlights the importance of organic-inorganic interfacial behaviour in coral strength.

To address the limitations of MD in simulating larger-scale interactions, we are applying coarse-graining methods that enable simulations of larger coral structures. Preliminary results support the notion that crystal-protein interactions and interfacial behaviors are critical to coral resilience, and ongoing work aims to extend these findings to mesoscale models that approximate entire coral skeletons. This research contributes to a clearer understanding of the factors underpinning coral strength, offering implications for coral conservation and resilience under environmental stress.