Characteristics of Plastic Debris Ingested by Sea Turtles: A Comprehensive Review

Abstract Sea turtles, an ecologically vital marine species, face the mounting threat of plastic ingestion. To devise effective mitigation strategies, a nuanced understanding of the characteristics of ingested plastics is essential. Previous reviews have predominantly concentrated on the frequency of occurrence (%FO) and quantity of ingested plastics. In this study, we present an update to the literature on %FO and quantity of ingested plastics and also introduce a novel review of the morphology, color, and polymer composition of ingested plastics. This analysis draws upon 110 scholarly articles on plastic ingestion by sea turtles. Additionally, we explore geographical variations in both the quantity and characteristics of ingested plastics. Most of the analyzed studies were conducted in the Americas and Europe. We found that approximately 54% of examined sea turtles had ingested plastic debris. Loggerhead sea turtles ingested more foams than green sea turtles (Wilcoxon rank-sum test, p < 0.05). By contrast, green sea turtles exhibited a higher ingestion on films (Wilcoxon rank-sum test, p > 0.05). Our study also underscored the paucity of data regarding the original usage of ingested plastics. White and transparent plastics were most commonly ingested. Additionally, polymers with a lower density than seawater, such as polyethylene, polypropylene, and their copolymers, were frequently found. We strongly advocate for future studies to furnish more comprehensive data regarding the ingested plastics, including quantities, morphological and chemical properties, and origins. Such detailed information is indispensable for shaping well-informed and effective strategies to combat plastic ingestion in marine life.