Micronization of ocean plastics threatens sea turtle populations and their life cycle

According to new research conducted by the Marinelife Loggerhead Center and the University of Georgia, the ingestion of degrading oceanic plastics is likely to pose a significant risk to the survival of sea turtles after they hatch, as particles can cause blockages and nutritional deficiencies. This jeopardizes the survival of all sea turtle populations, as sea turtles can take decades to become sexually mature. The study also suggests that micronization of plastics could have huge negative consequences for the ocean food web.

"We may be in the early stages of the first decline or extinction of the population of species associated with micronized plastic waste," said co-author Branson W. Ritchie, a veterinarian with more than 30 years of experience. experience in exotic and wildlife medicine. development and implementation of technologies for the UGA New Materials Institute. "But micronizing plastics are further affecting the ocean ecosystem, and as ocean plastics continue to micronize, the smaller creatures in our oceans are consuming smaller and smaller particles, compromising the entire food chain. animals, their ability to absorb the nutrients they need to survive decreases if the level of mortality observed in sea turtles after hatching also affects zoological plankton, baby fish and crustaceans, life cycle. "

The researchers collected 96 sea turtles after hatching, which had been washed off beaches along a stretch of the Florida coast between Vero Beach and Lake Worth. The area lies just south of the Archie Carr National Wildlife Refuge, named after the researcher who spurred the sea turtle conservation movement and is one of the largest rookeries in the United States for loggerhead and green turtles. More than 90% of the American population of loggerheads nests in Florida, said study co-author Charles Manire, veterinarian responsible for research and rehabilitation of the Marinelife Loggerhead Center.

Nearly half of the 96 turtles found were rehabilitated by LMC and released into the ocean. During their rehab time, all of them spent a certain amount of plastic, said Samantha Clark, a licensed veterinary technician, co-author who took care of turtles at LMC. The rest of the turtles collected died and 27 of them were examined for study. Ninety-three percent had a certain amount of plastic particles ingested, which led the team to think that many of them had died due to blockages or nutritional deficiencies associated with ingestion of plastic.

"Sea turtles are known to confuse ocular plastics with their prey, such as crab or fish eggs, or, in the case of large sea turtles, floating plastic bags for jellyfish," Clark said. .

"Our results suggest that far fewer newborns can survive long enough to reproduce, with devastating consequences for the seven species of sea turtles struggling to survive," said Manire. "If other populations of sea turtles experience similar mortality rates, we expect that there will be an insufficient number of newborns of sea turtles reaching sexual maturity to compensate for natural losses and other human losses. ".

Historically, researchers have estimated that only one in 1,000 people survive long enough to reach maturity, but some recent estimates suggest that this number could be 1 in 10,000.

As plastic waste has accumulated in the marine environment, reports describing the ingestion of plastics by sea turtles have increased. Plastic is now the most common form of marine debris. Globally, at least 690 marine species, including marine turtles, seabirds, seals, sea lions, whales, fish and invertebrates, would have become ill or died as a result of the disease. entanglement or ingestion of marine plastics.

The research team has made another remarkable discovery: once ingested, plastic particles can continue to deteriorate to such a small size that they have never been documented or described previously for particles ingested. Using Raman spectroscopy and Atomic Force Microscopy, the team characterized both the types of plastics and the particle sizes that they found.

"We found particles ranging from millimetric-sized fragments to nanoparticles averaging 52 nanometers, and smaller fragments measured at 5 nanometers," said Jason Locklin, director of the UGA New Materials Institute. "The smaller these particles are, the more unstable they become."

"Of these large mesoparticles, 54.1% were polyethylene and 23.7% polypropylene," said lead author Evan White, an associate scientist at the New Materials Institute, who analyzed the particles. "Polyethylene is the most widely used plastic and is mainly used for packaging, especially food packaging." Polypropylene is the second most commonly produced plastic and is used in many fields, including food packaging. "

For examples of scale, the microparticles include pollen, flour or powdered sugar. One nanometer is one billionth of a meter; a human hair has a width of about 80,000 to 100,000 nanometers.

The study was funded in part by the RWDC Environmental Stewardship Foundation, which has partnered with the UGA's New Materials Institute to research and develop fully biodegradable biosourced plastics.

The study team also included Shunli Wang, from the New Materials Institute, and Benjamin Crawford, an undergraduate student at UGA. The study, entitled "Ingested Micronizing Plastic Particle Compositions and Size Distributions in Sea Turtles" Science and technology of the environment.

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More information:
Evan M. White et al., Ingested Micronized Plastic Particle Compositions and Size Distributions in Sea Turtles Science and technology of the environment (2018). DOI: 10.1021 / acs.est.8b02776