Mariculture siting: a GIS description of intertidal areas

Variations in habitat parameters greatly affect the physiological state and the growth of bivalves. To achieve success in shellfish mariculture, environmental parameters favorable to the cultured species must be determined and then characteristics of potential grow-out sites evaluated. An intertidal bay in Eastern Maine was described in a GIS (geographical information system), which incorporated infrared aerial photographs and maps of bottom types, topography and bathymetry. Data layers included elevations from both nautical charts and GPS measurements made in the bay. From the elevation data, a series of programs was developed to generate a triangulated irregular network and a grid of elevations. A numerical flow model used the elevation grid to simulate a time series of tidal current vectors and free surface elevations. Gridded data from the numerical model were imported into the GIS and displayed as false color images of elevations, maximum current velocities and tidally averaged current velocities. Current vectors were layered over aerial photos showing sediment transport in the water. The GIS can be queried to identify sites for mariculture. A sample query identified sites for shellfish grow-out.