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Résumé de la communication de Jaap A. KAANDORP (University of Amsterdam, Nederland) donnée à l’occasion du séminaire Les constructions en milieu marin / Constructions in marine environment du 14 au 19 mars 2016Many branching scleractinian corals tend to develop symmetrical growth forms. A long-standing question is whether radial symmetrical colonies have emerged due to environmental conditions, such as water movement, or the genetic blueprint. To address this issue, we used a computational approach to study whether bi-directional currents cause the radial symmetrical morphology of representative branching corals. Using advectiondiffusion equations, we linked a three-dimensional coral growth model to simulate this, by varying bi-directional flow environments.We investigated the relative importance of flow to the corresponding symmetry of the simulated morphologies by changing the Peclet number. We compared the simulated results with in situ collected and CT-scanned colonies of the genus Madracis and the species Pocillopora verrucosa. The comparisons were based on 10 distinct morphometric traits comprising local morphometric traits, i.e. relevant to the local geometric property of the colony, and symmetry-oriented traits, that involve the measurement of how internal branches change relatively to the direction of the incoming flow.Our results show that morphometric characteristics of simulated corals under bi-directional flow environments correspond with those of real colonies. The threedimensional advection-diffusion and growth model is in principle suitable to investigate the influence of changing carbonate chemistry and stagnant zones on the growth process.During the presentation we will show some first examples of how we plan to couple the advection-diffusion model with a simple physiological model. We have constructed a model of calcification in which existing knowledge on the contributing sub-processes is integrated within a mathematical framework. In this model we have developed a spatial representation of the coral tissue in which we simulate the relevant chemical reactions in the surrounding environment, the transport processes of inorganic carbon and calcium ions through the different cell layers, photosynthesis, respiration and calcium carbonate precipitation.We model the spatio-temporal changes of the different processes as a set of coupled reaction-diffusion equations together with a new way of modeling transporters. Simulations can be employed to clarify the influence of different individual processes and reaction rates as well as changes in the chemical composition of the surrounding seawater.Summary