It is not fully understood how the global plastic waste crisis is affecting marine wildlife, despite decades of research and gruesome images of 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 federally protected, 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” as humans observe a tiny fraction of animal deaths in the ocean. Despite this, out of the country’s 23 coastal states, it has found cases in 21.
“This is the first time that we have 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 plastic 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.
The Oceana report found that in the reported cases, 90 percent of the animals had swallowed plastic and the rest became entangled in it. Autopsies often showed the animals to have died from blockages or lacerations. Other times, ingesting 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 trapping 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 against releasing balloons, which can harm marine animals.
Recently, some municipalities, counties and states have banned single-use plastic bags, one of the main factors of ingestion and entanglement, according to the report. Plastic wrapping straps have been found hugging 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 lines.
But the report also found that many other surprising things were causing damage. Along the Gulf Coast, bags of netting products have been found in the bowels of sea turtles and also entangled 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 slashed 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. Manatees, those gentle and slow giants that graze seagrass beds, accounted for 700 cases. 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: âImagine a ball of plastic bags in the stomach, the size of a cantaloupe, then a bunch of wrapped plastic bags 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 when 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 poorly developed 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 serious problems for marine animals: rising sea temperatures, fishermen carrying unwanted species, ships hitting them, other marine pollution and habitat degradation.
âPlastic itself may not be as big of a threat as we are led to believe,â said Jesse Senko, assistant research professor and senior scientist in sustainability at Arizona State University. “The scientific community hasn’t done a good enough job of really assessing these issues, looking beyond how they affect an individual animal.”
He believes the images of rotting seabirds with bellies full of plastic cause 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.
âI’m old enough to remember a time when it didn’t permeate everything in my life,â Dr. Warner said. “And yet it is piling up at an alarming rate.”