The Demise of the Sea Turtle Fluidly Translates to the Dangers for All Marine Life

Sea turtles have been traveling our oceans since the time of dinosaurs, but they are dying. Fast. Their migratory patterns, long lives, and eating practices have earned them the status of bioindicators for the health of our oceans, and the picture scientists are gradually developing is far from optimistic.

Coasting up the warm waters of the Gulf Stream, a Loggerhead sea turtle participates in one of the most impressive migratory behaviors of all animals on Earth. As it drifts along the North Atlantic gyre, however, it has to dodge plastic obstacles that litter its path. In the same way as ocean currents pull along marine creatures like sea turtles, they also sweep up much of the 8 million metric tons of plastic that enter our oceans every year, collecting them into vast patches of garbage. The damage is both visible and hidden, what we now regularly see on our beaches, for instance, as well as debris which is gradually eroded into tiny fragments called microplastics, inconspicuously making their way up the food chain. In 2018, the University of Exeter and Plymouth Marine Laboratory in the United Kingdom found microplastics in each individual sea turtle they studied all over the world. 

Loggerhead Sea Turtle

A Loggerhead Sea Turtle makes its way back to the sea.

Whilst the Loggerhead continues its quiet and silent trajectory in the Gulf of Mexico, on the other side of the world the largest of all sea turtles begins its migration in southeast Asia, crossing the entire Pacific Ocean, and swimming up along the coast of California until it reaches Alaska. Leatherback turtles can grow up to 6.5 feet (3 metres +) and their unique ability to survive in colder waters enables them to cover the largest geographic range of all turtles. As they travel from one corner of the world to the other, they feast on jellyfish they encounter along their path, which are increasingly replaced by a new identical twin: plastic bags. The physiology of turtles causes most ingested debris to remain in their digestive tracts for long periods of time, and as the victims of such deadly mistakes wash up on shore, they become ghoulish specimens for scientists to conduct research. Though it is nominally conducted on the turtle itself, such research ends up providing key information regarding the state of our oceans. 

“Turtles could eventually provide important clues to where garbage is the worst,” says Jennifer Lynch, a research biologist for the National Institute of Standards and Technology of the US Department of Commerce.

Researchers are currently working to map the size and distribution of plastic waste particles in order to obtain more information about the distribution and quantity of plastic pollution, and sea turtles have become a prime source of study. The research becomes more advanced as each year washes up more turtles, and is turning to new areas of focus like the presence of toxins, amount of trash, period of the sea turtle’s life, and type of species, as detailed in a 2018 report by Lynch.

As Leatherbacks choke on the artificial jellyfish, the threat of plastic contributes to a host of others that constitute their labeling as an endangered species, joined by five more of the seven species of sea turtles. Meanwhile, the real jellyfish population rises with the diminished presence of their top predator, and as these jellyfish freely feast on their diet of larval fish, fewer fish reach adulthood, impacting commercial fisheries around the globe. 

Further south, traveling the tropical waters of the Caribbean, Hawksbill turtles graze on the sponges of coral reefs. Preceding their name inspired by their hawk-like beaks is now the title “critically endangered.” Here we see the same problems recur, added to new ones on the list, as with dwindling Hawksbill numbers comes an upturn in the growth of sea sponges which overpower coral reefs, leaving the corals weak and susceptible to other environmental pressures. While vital coral reefs wither, sand dunes shift in the wind as fewer female sea turtles live long enough to climb out of the surf and lay their eggs. Without unhatched eggs and leftover eggshells providing nutrients to keep the dunes strong and healthy, the beach ecosystem erodes away. 

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Thousands of miles away in the Indian Ocean, because the range of the sea turtle spans almost the entirety of our vast global waters, a Green sea turtle grazes on beds of seagrass, adding to its viridescence while its eggs incubate on the shore of Mozambique. Its herbivorous lifestyle gives it the role of natural lawnmower, maintaining the health of seagrass while providing crucial developmental and breeding grounds for many species of fish. It plans to continue on for up to 80 years, the longest average lifespan of sea turtles, when the net of a zealous fisherman suddenly seals its fate. As he sips on his turtle soup, however, he is unaware that green pigmentation from sea grass is not the only thing the turtle had absorbed. Throughout its uniquely long life, the turtle had been ingesting microplastics and the accompanying toxins picked up at sea, traveling into its muscle tissue and realizing their final destination in the dinner of the unsuspecting consumer.

 

While Green turtles are more at risk of being hunted for food than other species of sea turtles, they are still considered a rare delicacy compared to all the species of mollusks, crustaceans, and fish that are commonly eaten all over the world. Turtles’ intake of plastic is studied to learn about how plastic travels its way up the food chain and contaminates not only the seafood we consume, but the water we drink. Additionally, certain types of plastic attract various toxins at sea that have been linked to cancer, autoimmune disease, and infertility. These toxin-infested plastics are then ingested by marine life, and eventually by us, making headlines when a 2019 study by the University of Newcastle in Australia published that humans eat approximately a credit card’s equivalent of plastic every single week.

 The demise of sea turtles fluidly translates to the dangers for all marine life, which results in the destruction of marine and coastal ecosystems, until it finally reaches us, and in a poignant statement by the Sea Turtle Conservancy, if we focus on saving this emblematic species, “we might just be saving ourselves too.”

Raquel Anais Smith is a freelance writer specializing in environmental features, published across a variety of international online and print media.