Predicting spatial and temporal shifts in oyster productivity with an oyster reef individual-based model

Abstract

Numerical models provide essential tools for evaluating dynamics and responses of aquatic resources under different management actions and environmental conditions. With a global decline in oyster reefs, the development of mechanistic oyster reef models can support their management and restoration. A spatially explicit three-dimensional individual-based model (IBM) for eastern oyster reefs in Barataria Basin (Louisiana, USA), was coupled with an estuarine Regional Ocean Modeling System hydrodynamic model to identify spatial and temporal sustainability, variation, and hot spots in oyster growth, survival, and reproduction under recent conditions (2014–2018). A series of oyster reef IBM point models were set up at a 2-km grid resolution. The IBM simulates daily individual oyster growth, mortality, and spawning of all oysters on each reef and how they structure 3-dimensional reefs. Temperature and salinity drive individual bioenergetics, spawning, recruitment, and mortality. Modelled size class densities and individual growth and fecundity were validated by qualitative agreement with available field data. Model simulations revealed hot spots in oyster production in areas with consistently higher salinities, identified as areas where oysters consistently thrived, and potential broodstock reef locations, identified as areas where reproduction consistently occurred. While the future integration of larval transport processes in the model is important to consider for metapopulation dynamics, this model framework enables testing different oyster restoration and management scenarios to evaluate oyster production and sustainability, providing critical data to help inform management.