The use of Benthic Terrain Modeler (BTM) in the characterization of continental shelf habitats

Abstract

We applied a combined approach of benthic terrain modelling with sediment type distribution, using regional available data sets in order to map the distribution of seabed physical habitats along the Espirito Santo Continental Shelf, Brazil. The Benthic Terrain Modeler (BTM) was used to define benthic terrain classes, which were combined with ground truth data (sediment samples and seabed images) to produce physical habitats (seascapes). Eight BTM classes were defined: flat bottom, rough, depression, valley flank, valley bottom, shelf break, crests, and deep crests. The combination of the BTM classes with sediment distribution produced 17 types of physical habitats. Analysis showed that shelf morphology controls the pattern of habitat distribution, combined with two major sedimentary processes: riverine sediment input and carbonate sedimentation. Seven types of physical habitats area associated with the flat bottom morphometric class, and five types of physical habitats are associated with rough/irregular morphometric classes. These are the two main broad categories observed along the shelf, when combined with the presence of rhodoliths. Shelf-incised valleys, combined with rhodolith beds, are the most conspicuous seascape along the ESCS. These seascapes add slope and roughness to the shelf seabed, producing great morphological complexity and potentially supporting diverse benthic communities.