Polymer Identification of Plastic Debris Ingested by Pelagic-Phase Sea Turtles in the Central Pacific

Abstract

Pelagic Pacific sea turtles eat relatively large quantities of plastic (median 5 g in gut). Using Fourier transform infrared spectroscopy, we identified the polymers ingested by 37 olive ridley, 9 green, and 4 loggerhead turtles caught as bycatch in Hawaii- and American Samoa-based longline fisheries. Unidentifiable samples were analyzed using high-temperature size exclusion chromatography with multiple detectors and/or X-ray photoelectron spectroscopy. Regardless of species differences in dive depths and foraging strategies, ingested plastics were primarily low-density, floating polymers (51% low-density polyethylene (LDPE), 26% polypropylene (PP), 10% unknown polyethylene (PE), and 5% high-density PE collectively). Albeit not statistically significant, deeper diving and deeper captured olive ridley turtles ate proportionally more plastics expected to sink (3.9%) than intermediate-diving green (1.2%) and shallow-diving loggerhead (0.3%) turtles. 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, account for the largest percentage of plastic eaten by sea turtles in this region. These novel data inform managers about the threat of plastic ingestion to sea turtles and may motivate development of more environmentally friendly practices for plastic production, use, and waste management.

Prey-size plastics are invading larval fish nurseries

“…3 F ; Materials and Methods , Polymer Identification ; SI Appendix , Table S2). These polymers are used in single-use consumer items (e.g., plastic bags, food cartons, and bottled water) (18) and in materials commonly used in marine-based industries, such as shipping, aquaculture, and fishing (e.g., crates, buckets, rope, and nets) (20). The most dominant polymer found in slicks, polyethylene (76.6%), is known to sorb pollutants more readily than other polymers and may serve as a vector for contaminants to marine fauna (21).…”

Ranking environmental degradation trends of plastic marine debris based on physical properties and molecular structure

“…Consequently, a large amount of data on physical (i.e., density, surface roughness, weight loss over time), thermal [i.e., melting temperature (T m ), glass transition temperature (T g )], and mechanical (i.e., modulus) properties have been measured along with molecular weight changes. Spectroscopic methods, like ATR-FTIR spectroscopy, and chromatographic techniques, such a gel-permeation chromatography (GPC), have greatly assisted in characterization of plastics 12 .…”

Critical Assessment of Analytical Methods for the Harmonized and Cost-Efficient Analysis of Microplastics

“…In the reviewed studies, FT-IR was performed either by measuring single particles, 16,54,59,81–150 via handheld FT-IR, 137,…”

“…For MP, this technique is often used in addition to screen the polymers for the presence of short polymer chains from weathering, 114,115,142 to understand the mechanisms behind particle fragmentation. Biver et al.…”

“…For MP, this technique is often used in addition to screen the polymers for the presence of short polymer chains from weathering, 114,115,142 to understand the mechanisms behind particle fragmentation. Biver et al 310 tested SEC for the application to identify PS and PE using fluorescence detection while Elert et al 179 used it for quantification of dissolved polymers against a calibration.…”