Microplastic ingestion ubiquitous in marine turtles.

ABSTRACT

Despite concerns regarding the environmental impacts of microplastics, knowledge of the incidence and levels of synthetic particles in large marine vertebrates is lacking. Here, we utilize an optimized enzymatic digestion methodology, previously developed for zooplankton, to explore whether synthetic particles could be isolated from marine turtle ingesta. We report the presence of synthetic particles in every turtle subjected to investigation (n = 102) which included individuals from all seven species of marine turtle, sampled from three ocean basins (Atlantic [ATL] n = 30, four species; Mediterranean (MED) n = 56, two species; Pacific (PAC) n = 16, five species). Most particles (n = 811) were fibres (ATL 77.1% MED 85.3% PAC 64.8%) with blue and black being the dominant colours. In lesser quantities were fragments (ATL 22.9% MED 14.7% PAC 20.2%) and microbeads (4.8%; PAC only; to our knowledge the first isolation of microbeads from marine megavertebrates). Fourier transform infrared spectroscopy (FT-IR) of a subsample of particles (n = 169) showed a range of synthetic materials such as elastomers (MED 61.2%; PAC 3.4%), thermoplastics (ATL 36.8% MED 20.7% PAC 27.7%) and synthetic regenerated cellulosic fibres (SRCF; ATL 63.2% MED 5.8% PAC 68.9%). Synthetic particles being isolated from species occupying different trophic levels suggest the possibility of multiple ingestion pathways. These include exposure from polluted seawater and sediments and/or additional trophic transfer from contaminated prey/forage items. We assess the likelihood that microplastic ingestion presents a significant conservation problem at current levels compared to other anthropogenic threats.