The vast Amazon River plume, a dynamic interface where freshwater meets the Atlantic, profoundly shapes life on the continental shelf. Our recent investigation, leveraging 21 years of satellite data and extensive benthic invertebrate records, reveals a clear and measurable link between the dispersal of particulate organic carbon (POC) from the Amazon and the structuring of these vital marine ecosystems. This research moves beyond associating POC production with river plume dynamics, to empirically demonstrating its influence on benthic biogeographic patterns across the Amazon–Guianas shelf. Understanding this relationship is critical, as it highlights how large-scale hydrological processes directly impact the foundation of marine food webs.
Our findings underscore the importance of regional circulation patterns, particularly the North Brazil Current, in advecting Amazon-derived POC northward. We identified distinct POC regimes across four shelf sectors, each exhibiting unique long-term concentrations. Crucially, these variations in POC availability, alongside other environmental factors like salinity and temperature, correlate with observable differences in the composition of benthic invertebrate communities. The analysis, employing sophisticated machine-learning techniques, indicates that plume-related signals, such as elevated POC and salinity minima, are particularly influential near the Amazon Mouth and Guiana regions. Conversely, hydrographic constraints become more dominant in the northern and Orinoco sectors, demonstrating a nuanced, region-specific control on benthic life.
This integrated approach, combining longitudinal data on river discharge, real-time satellite observations of POC, and comprehensive biodiversity records, provides a validated understanding of a complex oceanic system. The results emphasize that the Amazon River plume is not merely a surface phenomenon; its influence extends to the seafloor, dictating the diversity and distribution of benthic organisms. This knowledge is fundamental for effective ocean stewardship, informing our strategies for conservation and sustainable management in these highly productive yet vulnerable environments. By quantifying these connections, we enhance our capacity to predict ecological responses to changing riverine inputs and broader climatic shifts, fostering a more informed and collaborative approach to safeguarding our planet’s oceans.