Spatially explicit seston depletion index to optimize shellfish culture

Abstract

Cultivated bivalves rely on natural seston for growth and metabolic processes. Because seston is a limited resource, there is a need to better understand its distribution and fluxes within culture embayments, so farms can be positioned optimally within these dynamic systems. In this study, a simple numerical tool was developed and implemented to address actual management issues related to the positioning of oyster Crassostrea virginica farms in the Richibucto Estuary (eastern Canada). The versatile procedure relied on hydrodynamic modelling and tracer advection-dispersion to reproduce the spatial and temporal dynamics of seston availability. The model identified 3 areas of interest within the estuary, each with unique water renewal rates and seston concentrations. The method also revealed major interactions between the different areas, and proved efficient in quantifying the effects of topographical alterations on seston availability. Our results suggest that such basic modelling tools produce relevant information in a timely manner, and thereby facilitate the necessary dialogue between science advisors, industry stakeholders and resource managers.