Marine Animals as a Global Reservoir of Plastic Pollution: A Case Study
on Sea Turtles
Abstract
Marine wildlife ingest plastic pollution, making them a reservoir for
plastic debris and an important part of the “where is all the plastic”
puzzle. To date, we lack estimates of how much plastic pollution resides
within marine animals globally, making it difficult to reconcile the
fate of plastic pollution in the global ocean. To help fill this
knowledge gap, we collected data on amount of plastic debris found in
sea turtles necropsy studies from the scientific literature up until
January 1, 2020. We used this data along with predictor variables in a
regression model to quantify how much plastic resides within green
turtles (Chelonia mydas) globally for a snapshot in time. We found that
geographic, socio-economic, and ecological indicators significantly
correlate with how much plastic pollution is found in sea turtle
gastrointestinal tracts. Our model suggests that leatherback turtles
(Dermochelys coriacea) contain the most plastic in their
gastrointestinal tracts, and loggerhead turtles (Caretta caretta)
contain the least. This presents one of the first attempts to understand
which sea turtle species has the highest propensity for plastic
ingestion. We also provide the first estimate of a global marine animal
reservoir of plastic pollution – we estimate that at any given time,
green turtles carry 7.5-8.2 tonnes of plastic globally in their
gastrointestinal tracts.