As an intern at an oceanography laboratory in a small beach town on the Brazilian coast, we came across many beached sea turtles–some alive, most dead. While collecting measurements and tissue samples, we would also inspect the stomach contents of the dead sea-turtles we found. In the month that I worked in the laboratory, nearly every turtle that came across our dissecting table had the same story: they had starved to death, their stomachs blocked and filled with chunks of plastic that prevented them from swallowing real food.
In a global analysis, scientists found that anthropogenic (human-caused) debris ingestion, particularly plastic, has increased over time among sea turtles. Around the globe, ocean trash is threatening ancient and rare sea turtle species.
In the analysis, researchers analyzed data collected from before 1900 until 2012 to look at ingestion change over time, debris most commonly ingested, and which species are mostly affected.
Across the 37 studies analyzed, they found that that the probability of the green (Chelonia mydas) and leatherback turtles (dermochelys coriacea) ingesting plastic debris has significantly increased over time. While other sea turtle species are also found to ingest plastic, these species are particularly vulnerable because of their eating habits.
Green turtles are herbivores, eating only plant material. Bits of plastic, fishing line, or other trash floating in the ocean can smell just like food to an unsuspecting turtle. For this reason, carnivorous turtles are less likely to consume plastic than their plant-loving cousins, as described in the study.
Leatherbacks, the most ancient and bad-ass of sea turtle species, are not herbivores at all, but love to feed on jellyfish. A plastic bag, floating and swirling in deep-ocean tides, is often mistaken for a delicious meal, and will easily clog a digestive tract once swallowed.
The study also pointed out that nearly 70 percent of immature turtles ingested debris, whereas only 31 percent of adult turtles did. This means that not only are younger turtles more likely to ingest trash and debris, possibly from lack of “experience” in foraging, but their small and sensitive digestive tracts are also more vulnerable to damage and obstruction, which will be more likely to end in death.
As this study points out- ocean pollution is a global phenomenon. It is the tragedy of the commons: it is everyone’s problem, so it is nobody’s problem. Places like the Great Pacific Garbage Patch stretch for hundreds of miles, a floating junk “island” in the middle of the North Pacific Ocean. Sea turtles have a life history of long migration patterns, making debris management a difficult problem involving many national boundaries. Moreover, sea turtles are only one of the thousands of species that are affected by marine pollution.
To find out more about how marine debris is ends up in our oceans, and what happens once it gets there, check out Project Aware.
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