Global Surveillance of Offshore Oil Slicks: Linking Satellite Detection with Marine Biodiversity Patterns and Conservation Priorities

By combining satellite technology with ecological risk analysis, this study establishes a scalable global framework for tracking the environmental effects of chronic oil slicks. We used Sentinel-1 SAR from SkyTruth's Cerulean platform to detect surface slicks potentially attributable to over 24,000 fixed oil infrastructure and 326 FxO operating locations. We validated >2000 detections through expert review. This approach generates a replicable global database of offshore oil pollution sources, exemplifying a systematic method for identifying chronic polluters.We ranked offshore oil sources globally and within European and Mediterranean EEZs based on the percentage of satellite captures that contain attributed oil slicks. We overlaid validated slick locations with marine ecoregions, protected areas, and species occurrence data from the Map of Life. For nine identified chronically polluted regions—five global and four European/Mediterranean—we extracted species assemblages across concentric 50 km buffers. Chronic oil slicking correlated with consistent differences in assemblage composition and threatened species indicators. Species richness remains relatively stable across distance classes, but species composition shifts significantly. In European/Mediterranean waters, slick proximity explained >40% of the variation in community structure, surpassing the influence of fishing intensity or coastal proximity. Globally, polygons closer to chronic slick sites contain higher threatened-species representation in the Map of Life species lists. Beta diversity partitioning suggested that turnover dominated compositional differences among slick-proximate versus farther polygons, which supports compositional differences not explained by richness alone. These results pinpoint pollution hotspots with elevated ecological vulnerability, offering a pathway to align environmental monitoring with spatial conservation priorities.