CRED Fagatele Bay National Marine Sanctuary Bathymetric Position Index Habitat Structures 2004

Bathymetric Position Index (BPI) Structures are derived from derivatives of Simrad EM-3000 multibeam bathymetry (1 m and 3 m resolution). BPI structures are surficial characteristics of the seafloor based on a bathymetric position index value range at a combined fine scale and broad scale, slope values and depth. High-resolution multibeam bathymetry, derivatives of bathymetry (bathymetric position index, slope and rugosity), backscatter imagery and in situ visual survey data have been combined in a geographic information system (GIS). These data are supplemented by three-dimensional (3D) visualization. Within this study, methods were developed for benthic mapping and applied to three sites around American Samoa, a new classification scheme was developed for bathymetric position index (BPI) zones (depressions, slopes, flats, crests) and structures (finer features within zones) around the study sites, and visual survey information was associated with the results.