Geodiversity as an indicator to benthic habitat distribution: an integrative approach in a tropical continental shelf

摘要

Marine habitat mapping provides essential information for environmental management and design of marine reserves. In tropical regions, particularly along the Brazilian coast, the spatial variability of marine habitats is poorly known. The aim of this study is to evaluate the geodiversity of the region as an indicator to benthic habitat distribution, applying an integrative approach utilizing existing broad-scale bathymetric and seafloor geological data sets. A digital bathymetric model (DBM) of the Pernambuco Continental shelf (PCS) was generated at 80 m resolution from available bathymetric data. Through the benthic terrain model (BTM), DBM derivatives and the benthic structures were generated. These structures were combined with the textural seabed classification using tools in ArcGIS (TM) 10.5 Spatial Analyst to identify 22 seabed geomorphic features, including a submarine canyon confirmed around 8 degrees 20 ' S. These geomorphological features describe the surficial characteristics of the seafloor, providing the baseline for subsequent habitat-mapping studies, and can therefore be considered a potential habitat map. Three profiles taken to describe the cross-shelf seafloor environment (North, Center, and South) extracted from interpolated seabed geomorphological map revealed that sediment grain size becomes coarser from inshore to offshore, with predominantly sand and gravel sediment grain sizes. Overall, these results indicated a great potential for PCS due to the geodiversity present in the area, which leads to a higher biodiversity as well. Based on that, the central portion of PCS is suggested as a priority area for conservation because it was the most geomorphologically diverse. These terrain features influence the environmental conditions, such as currents, waves, nutrients, and other oceanographic parameters, which results in high diversity of benthic habitats in the region. This study presents a first step in characterizing the geomorphology of PCS by u