Floating plastic is ubiquitous at the surface of the ocean, but the transport mechanisms associated with the effect of environmental parameters including the presence of a biofilm to the polymers are very limited. Biofilm affects the object’s buoyancy and its density, hence impacting the distribution and sinking behaviors of plastics in the marine environment. Here, we assess the effect of biofouling on the rise velocity of positively buoyant polyolefins in the water column in environmentally relevant marine conditions. To establish whether biofouling influences the transport of plastics and enhances their removal from surface waters, we conducted a long-term monitoring experiment within a flow-through aquaculture system on Oʻahu, Hawaii using low-density polyethylene, high-density polyethylene (HDPE), and polypropylene of different sizes and shapes (films, rods, and cubes). Physico-chemical variables of the polymers were measured on a weekly and monthly basis, while environmental parameters such as light exposure, temperature, and chl a were monitored at higher resolution (days to minutes). Preliminary results show that HDPE and small size film has the potential to sink faster and that the surface area to volume ratio is the parameter influencing most the rise velocity when considering the different shapes and sizes. This study offers one of the first empirical data to incorporate into numerical models to assess the effect of biofouling on plastic rise velocities and helps predict the fate and sinks of positively buoyant plastics in the ocean.  

Primary Presenter: Sarah-Jeanne Royer, The Ocean Cleanup (sarah-jeanne.royer@theoceancleanup.com)

Authors:

Sarah-Jeanne Royer, The Ocean Cleanup  (sarah-jeanne.royer@theoceancleanup.com)

Kayla Brignac, Lehigh University  (kbrignac@hawaii.edu)

Kellie Teague, Hawaiʻi Pacific University - Center for Marine Debris Research  (kteague@hpu.edu)

Jennifer Lynch, Hawaiʻi Pacific University - Center for Marine Debris Research  (jmlynch@hpu.edu)

Laurent Lebreton, The Ocean Cleanup  (laurent.lebreton@theoceancleanup.com)