Habitat mapping for native oyster restoration using hydrodynamic modelling and experimental mortality data

Ostrea edulis has been harvested in Galway Bay, Ireland, for centuries, but the oyster aquaculture in the bay is facing multiple threats One major concern for oyster farmers in the bay is the recurrence of heavy-rainfall, high-runoff, low-salinity events. In this work, a high-resolution hydrodynamic coastal model of Galway Bay is used together with experimental data on oyster mortality to identify suitable areas for native oyster restoration. Here, a new coastal circulation model of Galway Bay is presented, and its performance is evaluated against in-situ temperature and salinity observations. Oysters were exposed at varying conditions of temperature and salinity in the laboratory and experimental cumulative mortality curves were determined. These experiments were used to develop an oyster mortality model that, together with the temperature and salinity predictions from the hydrodynamic model, determines the total mortality over a given period. A new Habitat Suitability Index is proposed, based on the distribution of total cumulative mortality.