Modelling feeding processes in bivalves: A mechanistic approach

Many bivalves species inhabit coastal waters where fluctuations in both quantity and quality of suspended particulate matter occur. The study of interactions between the organism and its environment requires thus a certain level of detail concerning the feeding process, not only from the bivalve point of view – which material can they actually use as food – but also from the ecosystem point of view – to what extent are bivalves able to clear the water column and change ecosystem dynamics? However such detail is commonly neglected in ecosystem modelling and a mechanistic description of the feeding process is still lacking. In this study, the Synthesizing Units concept, part of the Dynamic Energy Budget (DEB) theory, is used to describe the main feeding processes in bivalves. Filtration, ingestion and assimilation are assumed as three different steps and pseudofaeces production computed as the difference between filtered and ingested fluxes. Generic formulations are proposed and discussed, considering several types of food, with type-specific ingestion and assimilation efficiencies. The model performance is evaluated by comparison with the literature data for the blue mussel for a wide range of experimental conditions. The lack of data and of detailed information on the experimental setups adds some uncertainty to the parameters estimation. Nevertheless, the model results are in good agreement with observations. The model has the desired flexibility to be implemented as an extension to the standard DEB model, to simulate bivalve growth in estuaries and coastal areas where the organisms experience different food quantity and quality.