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

Abstract

Managers and scientists benefit from satellite-derived bottom type maps of coral reefs and other highly biodiverse 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 WorldView-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 pinnacles 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.