Modeling the radiative, thermal and chemical microenvironment of 3D scanned corals

Abstract

AbstractReef building corals are efficient biological collectors of solar radiation and consist of a thin stratified tissue layer spread over a light scattering calcium carbonate skeleton surface that together construct complex three dimensional (3D) colony structures forming the foundation of coral reefs. They exhibit a vast diversity of structural forms to maximize photosynthesis of their dinoflagellate endosymbionts (Symbiodiniaceae), while simultaneously minimizing photodamage. The symbiosis takes place in the presence of dynamic gradients of light, temperature and chemical species that are affected by the interaction of incident irradiance and water flow with the coral colony.We developed a multiphysics modelling approach to simulate microscale spatial distribution of light, temperature and O2in coral fragments with accurate morphology determined by 3D scanning techniques.Model results compared well with spatial measurements of light, O2and temperature under similar flow and light conditions. The model enabled us to infer the effect of coral morphology and light scattering in tissue and skeleton on the internal light environment experienced by the endosymbionts, as well as the combined contribution of light, water flow and ciliary movement on O2and temperature distributions in the coral.The multiphysics modeling approach is general enough to enable simulation of external and internal light, O2and temperature microenvironments in 3D scanned coral species with varying degrees of branching and morphology under different environmental conditions. This approach is also relevant for simulating structure-function relationships in other benthic systems such as photosynthetic biofilms and aquatic plant tissue, and can also be adapted to other sessile organisms such as symbiont-bearing giant clams, ascidians, jellyfish or foraminifera. The model could also be useful in more applied research such as optimization of 3D bioprinted constructs where different designs can be evaluated and optimized.