The severity of the global plastic waste crisis affecting marine wildlife is not fully understood, despite decades of research and gruesome images of a whale bellies filled with plastic and a turtle with a straw lodged in its nostril. A new report from Oceana, a conservation group, illustrates some of what we know about how plastic affects sea turtles and marine mammals in U.S. waters.
The results offer insight into a larger problem.
The authors have focused on sea turtles and marine mammals for practical reasons. These animals are protected by the federal government, so when they are found in distress or washed up dead on a beach, responders are required to document it. Collecting data from government agencies and marine life organizations across the country, the authors found nearly 1,800 cases of entanglement or ingestion of plastic affecting 40 species since 2009.
But the report notes that the number is “a gross underestimate” because humans observe a tiny fraction of animal deaths in the ocean. Even so, out of the country’s 23 coastal states, it has found cases in 21.
“This is the first time that we’ve looked at the problem from an American perspective,” said Kimberly Warner, author of the report and senior scientist at Oceana. “It brings the problem home.”
In 2016, the United States produced more plastic waste than any other country, and more of that plastics entered the ocean than previously thought, according to a recent study. In 2015, less than a tenth of the plastic waste accumulated in the world had been recycled.
Oceana’s report found that in the reported cases, 90% of the animals had swallowed plastic and the rest became entangled in it. Necropsies often showed the animals to have died from blockages or lacerations. Other times, the ingestion of plastic may have simply weakened the animal or played no part in its death. Overall, in 82 percent of cases, the animals died.
The culprits go beyond the usual suspects.
In the 1980s, environmental activists warned of the devastating effects of six-pack rings captivating marine animals. People began to dutifully cut them before their disposal, and in 1994 the Environmental Protection Agency required the six-pack rings to be degradable, although the process could take months. Consumers have also been warned of the release of balloons, which can harm marine animals.
Recently, some municipalities, counties and states have banned single-use plastic bags, one of the biggest contributors to ingestion and tangles, according to the report. Plastic wrapping straps have been found tightening the necks or bodies of seals and sea lions, naturally curious animals that may have become entangled when trying to play. Manatees ate a lot of fishing line.
But the report also found that there were many other surprising things that caused damage. Along the Gulf Coast, sacks of mesh products have been found in the bowels of sea turtles and entangling their bodies. In 2015, a loggerhead turtle in Georgia was found with a toothbrush and fork in its digestive tract, among other things. Two years later, another turtle was found in New York City with plastic dental floss inside. Food wrappers, sandwich bags, sponges and even decorative plastic Easter grass were among the items found. A North Carolina bottlenose dolphin had its head stuck in a hole in a flying disc. In Virginia, a DVD case tore the stomach of a sei whale.
Many victims are in danger or threatened.
More than a dozen endangered species – including sea turtles, Hawaiian monk seals and sei whales – have been ingested or entangled in plastic. The manatees, those gentle and slow giants that graze the seagrass beds, made up 700 boxes. The report quotes Brandon Bassett, a biologist with the Florida Fish and Wildlife Conservation Commission, describing some of what he found inside a dead manatee: “Imagine a ball of plastic bags in the stomach, the size of a cantaloupe, then a bunch of plastic bags that were wrapped and almost like a rope about 3 feet long.
Scientists are learning more about why animals consume plastic. For sea turtles, a floating plastic bag may look like a jellyfish meal, but that doesn’t explain the bottle caps and hard plastic shards found in their digestive tract or stool. One study suggested that plastic begins to smell appetizing as it becomes coated with algae and microorganisms.
In South Carolina, a sick loggerhead passed nearly 60 pieces of plastic through her digestive system while rehabilitating at a sea turtle center. Juveniles are at greater risk due to their size and underdeveloped gastrointestinal tract. More than 20 percent of sea turtles who ingested plastic were only a few months old. Some only had a few days. A recent Australian study found that just 14 pieces of plastic in their digestive tract significantly increased the risk of death for sea turtles.
Yet plastic waste is not the biggest killer of marine life.
Humans have created all kinds of terrible problems for marine animals: rising sea temperatures, fishermen carrying unwanted species, ships hitting them, other marine pollution and habitat degradation.
“Plastic itself may not be as big of a threat as we think it is,” said Jesse Senko, assistant research professor and senior sustainability researcher at Arizona State University. “The scientific community has not done a job effectively enough to really assess these issues, beyond how they affect an individual animal.”
He believes images of rotting seabirds with bellies full of plastic are causing the public and media to focus on plastic, even when other threats are greater.
Ultimately, plastics and rising sea temperatures are linked; after all, the vast majority of plastic is derived from fossil fuels.
The Oceana report calls on national, state and local governments to restrict the production of single-use plastics and calls on companies to provide consumers with plastic-free options.
“I’m old enough to remember a time when it didn’t permeate everything in my life,” said Dr. Warner. “And yet it is accumulating at an alarming rate.”