In response to changing climate, flood protection response, and land use patterns, the historic oyster reefs in Mississippi have endured unprecedented declines in recent years, despite significant resources committed to their recovery. For such restoration efforts to succeed, it is critical that we understand how changes to coastal water quality/quantity will affect habitat suitability for the gamut of oyster age classes throughout the MS Sound, and how this information can be used to inform and improve natural resource management policy.
To this end, we have developed a Habitat Suitability Index (HSI) model of the four main age-classes of Eastern oyster (larvae, spat, seed, and sack), coupled with water quality observations and hydrodynamic model output from the Coupled Ocean Atmosphere Wave Sediment Transport Modeling System (COAWST) in a domain that captures riverine forcings to the Mississippi Sound & Bight, from Mobile Bay to the Birdfoot Delta. HSI model analyses comparing the likely performance among spat, seed, and sack oysters on existing reefs within MS Sound, in response to seasonal temperature and salinity dynamics, indicate that spat are the most sensitive age-class to "within-year" environmental impacts on habitat suitability. In the warm waters of the MS Sound, spat are promoted to seed within a matter of months, whereafter seed oysters become the most sensitive age-class to "across-year" environmental stressors, particularly November to March. Thus, future oyster restoration efforts should focus on maximizing habitat suitability relative to temporal gradients of environmental stress, particularly for younger classes of settled oysters.