Polymer Identification of Plastic Debris Ingested by Pelagic-phase Sea Turtles in the Central Pacific
Jennifer M. Lynch, Sara V. Orski, Kathryn L. Beers
Pelagic Pacific sea turtles eat large quantities of plastic. We identified the polymers ingested by 37 olive ridley, 9 green and 4 loggerhead sea turtles caught as bycatch in Pacific longline fisheries using Fourier transform infrared spectroscopy. Unidentified samples were analyzed using high temperature size exclusion chromatography with multiple detectors and/or x-ray photoelectron spectroscopy. Ingested plastics were 51% low-density polyethylene (LDPE), 26% polypropylene (PP), 10% unknown PE, and 5% high-density PE, all of which should float in seawater based on their density. Albeit not statistically significant, deeper diving, and deeper captured, olive ridleys ate proportionally more plastics expected to sink (3.9 %) than intermediate foraging greens (1.2 %) and shallow loggerheads (0.3 %). Spatial, but no sex, size, year or hook depth differences were observed in polymer composition. LDPE and PP, some of the most produced and least recycled polymers worldwide, represent the largest percentage of plastic eaten by sea turtles in this region. These novel data describe additional details of this threat to sea turtles and may motivate development of more environmentally-friendly practices for plastic production, use and waste management.