Modelling macroalgae using a 3D hydrodynamic-ecological model in a shallow, temperate estuary

This paper describes an application of MOHID modelling system to a shallow temperate coastal lagoon in Portugal's western coast (Ria de Aveiro), simulating more than one primary producer, for a better understanding of the existing ecological dynamics and creating a useful tool to delineate land activities management practices. MOHID water quality model is driven by a physical transport model and simulates the dynamics and productivity of the two main primary producers (phytoplankton and macroalgae) as well as the cycling of nitrogen, carbon and oxygen in interaction with sediment and hydrodynamics. The integrated model is forced by exchanges with the Atlantic Ocean (tide), atmosphere, and by sediment and nutrient inputs from the upstream rivers and other discharges. Focus is given to the light parameterization of primary production, influence of hydro and sediment dynamics and to the prediction of seaweed beds distribution. The results obtained show that the model is better adjusted to field data with macroalgae's simulation and that macroalgae can have an important role in primary production. Hydrodynamic conditions can be significant in the competition between the two primary producers, determining the predominant groups as well as their limiting factors.