Anthropogenic microparticles across intertidal, shallow and mesophotic reef sediments in the Southwestern Atlantic

The distribution of anthropogenic microparticles (AMPs) in reef sediments across different depths and along gradients of estuarine and urban influence remains poorly documented. This study provides baseline information on AMPs in sediments from intertidal (0-2 m), shallow (17-19 m), and mesophotic (30 m) reefs in the Southwestern Atlantic. Concentrations ranged from 73.27 to 1246.45 particles kg^-1 dry weight, with the highest values recorded in intertidal reefs located closest to estuarine inputs. A total of 384 particles were recorded, predominantly fibers, while transparent and blue particles were the most common colors. Raman spectroscopy was used to identify particles, including plastic polymers such as polypropylene and polyethylene terephthalate (PET), as well as non-plastic particles composed of microcrystalline cellulose. Color composition differed among reef sites, with similar patterns observed in intertidal reefs adjacent to urbanized estuaries and in offshore shallow and mesophotic reefs. These findings provide baseline information on the occurrence, characteristics, and spatial distribution of anthropogenic microparticles in reef sediments across a tropical shelf gradient, contributing to a better understanding of microplastic and textile-derived contamination in understudied reef environments.