A dynamic energy budget model: parameterisation and application to the Pacific oyster Crassostrea gigas in New Zealand waters

A dynamic energy budget (DEB) model was developed and applied to the Pacific oyster Crassostrea gigas in central New Zealand. The model was based on DEB theory and developed prior to empirical information according to a common mechanistic rule in organisms' physiology. Subsequently, both laboratory and field experiments were specifically designed to collect datasets for parameter estimation and testing of the model. This approach to the modelling aimed to reduce uncertainties in parameter estimates and hence improve the applicability of the model. A lab-based starvation experiment was done over 170 days. Changes in body flesh weight were monitored and the respiration rate was measured. Dry flesh weight and the oxygen consumption rate decreased by 63.4% and 44.0% respectively over the experiment. Ash free dry flesh weight was proportional to the dry flesh weight, with coefficients of 83.5% and 58.7% respectively at the beginning and late stages of the experiment. Field-based growth experiments were done on a marine farm at two depths over 150 days to obtain biological and environmental information. The growth rate of oysters at 8 m depth was significantly greater than at 32 m depth. Chlorophyll-a concentration was highly variable, both spatially and temporally. Variation between depths provided ideal information for validation of the DEB model. Estimates of model parameters were augmented from studies in a local population. In comparison with previous studies on the same species from other ecosystems in the world, intraspecies variation was apparent in some parameters including maximum surface area-specific assimilation rate, which governs the ability of an individual for energy acquisition, and the fraction of energy utilisation rate used for maintenance plus growth, which determines energy fluxes to different components. The maximum storage density and volume-specific cost for growth also showed considerable intraspecies variability. Application of the model developed here showed that it is capable of simulating energetics and growth of the oyster in the growing area of central New Zealand.