Scientists have finally measured just how bad ocean plastic pollution is for these majestic animals.
Sea turtles have been around since the time of dinosaurs, dating back 110 million years. They are one of the most ancient creatures on Earth, but in the past 50 years their world has undergone drastic changes. Plastic pollution in the oceans has wreaked havoc on sea turtle populations. Many turtles wash up on beaches tangled in plastic, and post-mortem studies have revealed bellies full of ingested plastic.
A group of scientists set out to quantify the risk that plastic pollution poses to declining sea turtle populations in a world where plastic production is steadily increasing. Using data from 246 necropsies and 706 records of coastal strandings, the resulting study was just published in Scientific Reports, and it makes some disturbing discoveries.
The researchers found that ingesting a single piece of plastic increases a sea turtle's risk of death by 22 percent. If a turtle ingests 14 items, the chance of death rises by 50 percent.
The likelihood of ingesting plastic is higher for baby and juvenile turtles, who tend to float on the surface of the water and stay farther out to sea than adult turtles; unfortunately this is also where much of the plastic floats. Lead author Dr. Britta Denise Hardesty of the Commonwealth Scientific and Industrial Research Organisation in Australia, told BBC:
"Young small turtles actually drift and float with the ocean currents as does much of the buoyant, small lightweight plastic. We think that small turtles are less selective in what they eat than large adults who eat sea grass and crustaceans; the young turtles are out in the oceanic area offshore and the older animals are feeding in closer to shore."
Exacerbating the problem is the fact that sea turtles cannot regurgitate unwanted food or items. Everything they eat stays in their digestive tract for 5 to 23 days, and plastic disrupts this process. It creates obstructions by taking excessive time to pass through (up to 6 months) and by forming blockages. From the study:
"One feeding experiment found that, rather than passing through the GIT individually, pieces of soft plastic could compound together and pass as a single compacted item, despite being ingested at separate intervals."
The scientists found that 23 percent of juveniles and 54 percent of post-hatchling-stage turtles had ingested plastic, compared to 16 percent of adults. In other words, this poses a very serious problem for the future viability of sea turtle populations. Dr. Hardesty explained,
"We know that disproportionately finding it more in younger animals who won't make it to the reproductive state will have long term consequences for the survival of the species."
Studies like this one are critical for understanding the effect that human consumption and waste have on the natural world, but they are incredibly discouraging too. All one can do, really, is come away from the research with a new commitment to eliminating plastic from one's personal life and a determination to fight for new policies and institutional changes that will further the fight as well. For guidance and inspiration, take a look at the many posts we've done on plastic-free living -- links shown below.