The Rio Grande Rise (RGR), a large and complex submarine feature in the southwestern Atlantic Ocean, was systematically mapped to investigate its geomorphology, substrate heterogeneity, and benthic habitat distribution. High-resolution multibeam bathymetry provided the basis for deriving terrain variables, used to classify major geomorphic units, including plateaus, ridges, and canyons. Seafloor backscatter mosaics and video imagery, analyzed with object-based image analysis, revealed distinct substrate types including ferromanganese crusts, foraminiferal sands, and pteropod shell beds. Bedforms, such as polygonal patterns, circular depressions, and waveforms, indicate active bottom currents and potential fluid migration that shape the terrain. Faunal assemblages differed markedly across habitat types, showing clear associations with substrate and local geomorphology. Patchy sediments on gentle slopes support diverse assemblages with complex trophic dynamics involving mobile predators, scavengers, and a range of invertebrates. Muddy flats and slopes enriched in organic matter host detritivores and burrowing fauna adapted to unconsolidated substrates. Sessile suspension feeders, including corals, sponges, echinoderms, and ascidians, dominated hard-substrate plateaus exposed to hydrodynamic activity. Slopes shaped by gravitational processes and covered with unsorted sediments host opportunistic species sharing functional traits with assemblages from patchy sediment habitats. The resulting habitat map provides a spatial framework for benthic environments across the RGR and documents marked habitat heterogeneity. The absence of systematic biological and sediment sampling constrains the resolution of habitat classification and some areas and taxa were under-sampled. Nevertheless, the outcomes establish a valuable environmental baseline that can guide future research, conservation planning, and resource management in the deep sea.
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