Bioaccumulation of heavy metals in estuaries in the southwest Atlantic Ocean

The southwestern Atlantic Ocean is home to highly productive regions, composed of a mosaic of both protected and anthropogenically impacted areas, including the estuaries of Paranaguá, Cananéia, and Santos. In this study, concentrations of metals were measured in sediments and in marine organisms, collected from these three Brazilian estuaries. The higher concentrations of metals in the sediments from the Santos estuary are due to having the greatest intensity of anthropogenic activities. There is bioaccumulation of As, Cu, Ni, and Pb in benthic invertebrates, As in fish, and Se and Zn in all studied trophic groups. Comparing the biota among estuaries, levels were highest for Cr, Cu, Pb, Se, and Zn in Paranaguá, As in Cananéia, and Ni in Santos; results justified due to anthropogenic activities, natural sources, and geochemical and hydrodynamics characteristics of each region that affect the bioavailability of metals. The results showed that these regions of the Atlantic present higher levels of metals in the biota than several coastal regions worldwide, and signal that food security may be compromised. Highlighting the need for better impact assessment, monitoring, and managing is deemed necessary as these regions are globally recognized as hotspots of biodiversity and are considered priority areas for conservation.