2023 Theses Master's

Life In Plastic, It’s Not Fantastic: Quantifying the Frequency and Type of Pelagic Plastic Debris Ingested by Olive Ridley Sea Turtles (Lepidochelys olivacea)

Arango, Hailey

Ingestion of pelagic plastic debris is dangerous for marine biota. Deceased turtles caught by longline fisheries may be a valuable source of information regarding the ingestion of pelagic plastic debris. I necropsied 28 olive ridley sea turtles (Lepidochelys olivacea) that were collected as bycatch throughout the Hawaiʻian and American Samoa-based longline fisheries between February 2015 and April 2021, extracted their gastrointestinal tracts, and removed all plastics for analysis. Plastics were organized into groups based on color, thickness, and type, and compared across capture location, year, turtle length, sex, and body condition. Of the olive ridley turtles sampled in this study, 92.9% had ingested plastic. Plastic fragments (>2.5cm) were the most common debris type, making up 92.3% of the ingested debris by mass. I found that the turtles consumed debris that were mostly white (61%), followed by blue (12%) and green (9%). I identified the polymer composition of all ingested plastic pieces through attenuated total reflectance – Fourier transform infrared spectroscopy. Polyethylene polymers made up the majority of all debris ingested (61.8%) and made up a larger proportion of ingested plastic mass in the Northern Hemisphere than in the Southern Hemisphere. There were significant differences in the polymer compositions of the debris colors. Most of the blue plastics were PE/PP, whereas PE made up a majority of most other colors. EVA and PS polymers made up a larger percent of clear plastics than any other color. These analyses will add to the literature on the threat of pelagic plastic ingestion and provide insight into the potential impacts of prolonged contaminant exposure in sea turtles.