Microplastics and microfibers in surface waters of Monterey Bay National Marine Sanctuary, California

Despite a recent report of high concentrations microplastics and microfibers in the mesopelagic waters Monterey Bay National Marine Sanctuary (MBNMS), little is known about these particles surface waters. From 2017 to 2019, we sampled two nearshore offshore locations within MBNMS using manta trawl analyzed samples for microfibers. We found an average concentration 1.32 ± 0.70 (SE) per m3. highest closest shore, lowest above remote Davidson Seamount. Fiber-like debris was more common offshore, as compared nearshore, sites. Overall, our were primarily buoyant synthetic polymers, including polypropylene polyethylene. Our results provide baseline data on degree microplastic microfiber pollution confirm that this can be from at least 1000 m depth.