Is Plastic Degradation Occurring in the Deep Ocean?

Since 1950, global production of plastic has grown exponentially. An estimated 5 to 13 million metric tons of plastic flows from the land into the ocean each year. However, 99% or more of the plastic entering the ocean is currently unaccounted for, according to models.

With support from the NSF 2026 Idea Machine program in the National Science Foundation’s Office of Integrated Activities, a team of researchers from four institutions will investigate the processes that affect plastics once they enter the ocean. Lead Principal Investigator Rut Pedrosa Pàmies of the MBL Ecosystems Center says “the main goal of the project is to understand the physical modification and biochemical transformation of plastic by microbial communities in the deep ocean.”

Rut Pedrosa Pàmies near a sediment trap during a redeployment of the Oceanic Flux Program mooring onboard the R/V Atlantic Explorer. (Photo credit: JC Weber)

This NSF collaborative grant bring together an interdisciplinary research team including Principal Investigator Pedrosa Pàmies and Co-Principal Investigators Zhanfei Liu (University of Texas at Austin, Marine Science Institute), Alexander Bochdansky (Old Dominion University), Emil Ruff (Marine Biological Laboratory) and Scott Gallagher (Coastal Ocean Vision), and collaborators Jessica Mark Welch (Marine Biological Laboratory) and Maureen Conte (Bermuda Institute of Ocean Sciences, and Marine Biological Laboratory).

The investigators will deploy incubators containing well-defined plastic polymer films and fibers to evaluate plastic degradation at 600 meters and 3,600 meters water depth at the NSF-funded Oceanic Flux Program (OFP) mooring site, located in the Sargasso Sea about 75 km southeast of Bermuda. This project will combine state-of-the-art polymer chemistry analyses with microscopy, and lipid and nucleic acid sequencing analyses. Deploying deep-sea incubators on the OFP mooring is a new method to study plastic polymer degradation processes in situ, and this research contributes significantly to technology development for oceanographic research.

Results from this project will further understanding of the mechanistic processes that govern degradation of plastic particles in the mid-depth and deeper ocean. It will also determine if there are microbial communities at those depths that can actively degrade and utilize the synthetic carbon polymers that make up plastics. Results from this project will also provide insights into the global budget of plastics, potentially filling the knowledge gap on the fate of plastic and thus affecting plastic management policies. Knowledge of the role of deep ocean microbial communities in the degradation of synthetic plastic polymers will be very valuable information for industry and policymakers. The collaboration of the American Chemistry Council, which is providing support for polymers for the project, will strengthen the cooperation between academia and industry.