Use of dynamic energy budget and individual based models to simulate the dynamics of cultivated oyster populations

We successfully tested a Dynamic Energy Budget (DEB) model of the oyster Crassostrea gigas using published environmental data and growth data collected in Thau lagoon (France). Estimates of most DEB parameters were based on independent datasets and only two parameters were calibrated using our datasets: the shape parameter, which was used to convert body volume into shell length, and the half-saturation coefficient, which controlled the functional response of assimilation to food concentration, represented by chlorophyll-a concentration. The DEB model proved to be robust and generic: it was able to reproduce oyster growth in Thau lagoon and other ecosystems. We also assessed population dynamics by coupling DEB equations and an Individual Based Model (IBM) of cultivated oyster populations. The results were compared with previously published simulations of harvested production and standing stock based on an empirical growth equation and a partial differential equation of population dynamics. Differences between the two studies were explained by the difference between the predictions of oyster growth with the empirical and the DEB models. We also accounted for growth variability between individuals and showed that IBM offers a powerful alternative to continuous equations when several physiological variables are involved.