Spatial distribution patterns of coral reefs in the Abrolhos region (Brazil, South Atlantic ocean)

Managers and scientists benefit from satellite-derived bottom type maps of coral reefs and other highly bio-diverse coastal ecosystems. Here, we generated a map of the coral reefs within the Abrolhos National Marine Park (ANMP), one of Brazil's most iconic marine protected areas, using a very-high-spatial-resolution World -View-2 (WV02) image and field observations. A particular geomorphology characterizes this region, where reefs grow in columnar pinnacles with different top height and dimensions (1-25 m height and 1-50 m diameter). The WV02 image went through three different processing steps (corrections for atmosphere, sun-glint and water column effects) to retrieve the bottom signal at 478 nm, which was used to produce a bottom map from an object -based image analysis (OBIA) and to evaluate reef distribution through landscape metrics. A bottom map with 64% of overall accuracy was obtained. Reef distribution showed a heterogeneous aggregation pattern of pin-nacles to the East of the Abrolhos archipelago as well as the vegetated bottom around the archipelago. The novel map presented herein may guide management strategies of the AMNP, provide a background for connectivity studies, and help address the evolution (i.e., biogeomorphology processes) of the unique shallow Abrolhos reef structures.