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Do loggerhead sea turtle (Caretta caretta) gut contents reflect the types, colors and sources of plastic pollution in the Southwest Indian Ocean?

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September 2023, article in a peer-reviewed journal
Marine Pollution Bulletin

Margot Thibault, Ludovic Hoarau, Laurent Lebreton, Matthieu Le Corre, Mathieu Barret, Emmanuel Cordier, Stéphane Ciccione, Sarah-Jeanne Royer, Alexandra Ter Halle , Aina Ramanampamonjy, Claire Jean and Mayeul Dalleau

  • Publication type: Article in peer-reviewed journal
  • Publication journal: Marine Pollution Bulletin
  • Publication date: September 2023
  • Collaborators: UMR ENTROPIE, University of Reunion Island, Reunion Island (FR), Centre d'Étude et Découverte de Tortues Marine (CEDTM), Reunion Island (FR), The Ocean Cleanup (NL), Kelonia, The Marine Turtle Observatory of Reunion Island, Reunion Island (FR), Osu-Réunion, University of Reunion Island, Reunion Island (FR), CNRS, Université Toulouse III, Laboratoire des Interactions Moléculaires et Réactivité Chimique et Photochimique (IMRCP) (FR), Association CETAMADA (MG)
  • DOI: /10.1016/j.marpolbul.2023.115343

Abstract

We analyzed plastic debris ingested by loggerheads from bycatch between 2007 and 2021 in the Southwest Indian Ocean (SWIO). We also analyzed plastic debris accumulated on beaches of the east coast of Madagascar as a proxy for ocean plastics to compare the characteristics of beached plastics and plastic ingested by turtles. We conducted a “brand audit” of the plastics to determine their country of origin. An oceanic circulation model was used to identify the most likely sources of plastics in the SWIO. In total, 202 of the 266 loggerheads analyzed had ingested plastics. Plastics categorized as “hard” and “white” were equally dominant in loggerheads and on beaches, suggesting no diet selectivity. Both the brand audit and circulation modeling demonstrated that Southeast Asia is the main source of plastic pollution in the region. This study demonstrates that loggerheads can be used as bioindicators of plastic pollution in the SWIO.