Abstract
The ingestion of plastic by marine turtles is now reported for all species. Small juvenile turtles (including post-hatchling and oceanic juveniles) are thought to be most at risk, due to feeding preferences and overlap with areas of high plastic abundance. Their remote and dispersed life stage, however, results in limited access and assessments. Here, stranded and bycaught specimens from Queensland Australia, Pacific Ocean (PO; n = 65; 1993–2019) and Western Australia, Indian Ocean (IO; n = 56; 2015–2019) provide a unique opportunity to assess the extent of plastic (> 1mm) ingestion in five species [green (Chelonia mydas), loggerhead (Caretta caretta), hawksbill (Eretmochelys imbricata), olive ridley (Lepidochelys olivacea), and flatback turtles (Natator depressus)]. In the Pacific Ocean, high incidence of ingestion occurred in green (83%; n = 36), loggerhead (86%; n = 7), flatback (80%; n = 10) and olive ridley turtles (29%; n = 7). There was an overall lower incidence in IO; highest being in the flatback (28%; n = 18), the loggerhead (21%; n = 14) and green (9%; n = 22). No macroplastic debris ingestion was documented for hawksbill turtles in either site although sample sizes were smaller for this species (PO n = 5; IO n = 2). In the Pacific Ocean, the majority of ingested debris was made up of hard fragments (mean of all species 52%; species averages 46–97%), whereas for the Indian Ocean these were filamentous plastics (52%; 43–77%). The most abundant colour for both sites across all species was clear (PO: 36%; IO: 39%), followed by white for PO (36%) then green and blue for IO (16%; 16%). The polymers most commonly ingested by turtles in both oceans were polyethylene (PE; PO-58%; IO-39%) and polypropylene (PP; PO-20.2%; IO-23.5%). We frame the high occurrence of ingested plastic present in this marine turtle life stage as a potential evolutionary trap as they undertake their development in what are now some of the most polluted areas of the global oceans.
Highlights
Plastic debris is one of the most ubiquitous and long-lasting pressures to marine systems (Barnes et al, 2009; Jambeck et al, 2015) and it has been estimated to interact with over 700 species (Gall and Thompson, 2015; Kühn and Van Franeker, 2020)
A large proportion of the small juveniles sampled had ingested plastic (>1mm) this varied by species and by ocean (Figure 1) with none of the smaller number of hawksbill turtles in either ocean showing evidence of plastic ingestion
The highest number of plastic pieces ingested occurred in green turtles, with the maximum number of pieces ingested by a single animal being 144 and 343 pieces, in samples from the Pacific Ocean (PO) and Indian Ocean (IO), respectively
Summary
Plastic debris is one of the most ubiquitous and long-lasting pressures to marine systems (Barnes et al, 2009; Jambeck et al, 2015) and it has been estimated to interact with over 700 species (Gall and Thompson, 2015; Kühn and Van Franeker, 2020). Plastic ingestion is widely recognised to occur in all species of marine turtle (Schuyler et al, 2014; Nelms et al, 2016; Lynch, 2018), population-scale impacts have not been demonstrated (Senko et al, 2020). Drivers behind marine debris ingestion have included visual selectivity (Schuyler et al, 2012; Fukuoka et al, 2016; Duncan et al, 2019a), odour (Pfaller et al, 2020), or failure of discrimination when mixed with normal dietary items (Di Beneditto and Awabdi, 2014). Synthetic particles (
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
