Benthic biodiversity of the Brazilian Equatorial Margin: a systematic review with recommendations for conservation priorities and research

Abstract

The Brazilian Equatorial Continental Margin, encompassing Maranhão, Pará, and Amapá, hosts ecologically and economically significant marine ecosystems that remain poorly investigated. In recent years, the region has gained international attention due to proposed hydrocarbon exploration and the discovery of extensive reef systems near the Amazon River mouth, raising concerns about potential impacts on sensitive coastal and shelf environments. Here, we present the first systematic review of benthic biodiversity across the continental shelf and slope of this margin. Following PRISMA guidelines, literature searches in major scientific databases and complementary manual screening retrieved over 4,000 records, of which 13 met the inclusion criteria. These studies documented 15 phyla, 407 genera, and 498 benthic species, with Nematoda, Cnidaria, Arthropoda, and Mollusca comprising the most diverse groups. Research effort shows a strong taxonomic bias toward megabenthos and megafauna (11 studies), whereas meiofauna and microbenthos remain largely understudied. Nearly half of the selected publications appeared within the last four years, reflecting growing scientific and industrial interest. However, deep-sea habitats (> 2,000 m) and long-term monitoring initiatives are still scarce. Comparison with other Brazilian margins and tropical regions underscores substantial knowledge gaps and the need for coordinated research and conservation strategies in this Atlantic frontier.