Tiny plastics can kill marine wildlife: Study raises alarms for Pacific islands

By Ron Rocky Coloma

The case that stayed with Dr. Erin Murphy involved a sea turtle with eight plastic bags in its stomach. Another autopsy uncovered a plastic water bottle inside an albatross. A sperm whale died with a stomach packed with dozens of bags, rope and fishing nets.

Each death became a data point in a global analysis of how plastic ingestion kills marine wildlife, but for Murphy, they were also reminders of how close the problem sits to coastal communities, including those across the Pacific islands.

Murphy, Ocean Conservancy’s manager of ocean plastics research, said she expected to see damage from large plastic items. What surprised her was how little plastic it takes for many species to reach a fatal threshold.

“For the first few months, while I collected data from the literature, I was deeply saddened to read about the animals that died from plastic ingestion,” Murphy said.

“It really hit me that this study might change how we understand how plastic kills animals when I ran the first versions of the models to estimate the chance of death based on plastic ingestion. When I saw just how small the amounts of plastic were that could lead to a 50 percent chance of death, it was eye-opening to me.”

The research reviewed thousands of autopsies on seabirds, sea turtles and marine mammals. According to Murphy, the models showed that a 50 percent chance of death can result from ingesting what would seem like small, harmless fragments.

“The idea that such small doses of plastic could make the chance of survival the same as a coin flip felt like a chance we can’t afford to take,” she said.

Murphy said she once imagined plastic ingestion as animals swallowing entire bags or discarded fishing gear. Her findings show that as plastic breaks into smaller pieces, the danger remains.

“Simply put, there is no ‘safe’ size or level of plastic in our ocean,” she said. “We only looked at physical harms of plastic ingestion such as punctures, twisting and blockages of the GI tract, and didn’t account for chronic and chemical impacts of plastic ingestion, the impacts of microplastics or entanglement.”

One of the most surprising results came from seabird data, showing “how low the rubber ingestion mortality threshold for seabirds was,” she said.

Just six pieces of rubber, each smaller than a pea, were 90 percent likely to cause death in a seabird.

Nearly half the animals that ingested plastic in the dataset were considered threatened under the IUCN Red List, Murphy said. Sea turtles stood out.

“Roughly 5 percent of sea turtles in our dataset died from plastic ingestion, and five out of seven sea turtles are currently IUCN-redlisted as threatened,” she said.

For the Pacific islands, where endangered sea turtle populations are culturally and ecologically significant, the findings raise particular concern. Many Pacific communities depend on healthy turtle and seabird populations for ecosystem balance, tourism and long-standing cultural practices.

The Pacific region, which includes some of the world’s most plastic-polluted coastlines, is already grappling with currents that funnel marine debris toward islands such as Palau, Guam, the Marshall Islands and Hawai‘i. Murphy said the study’s implications are especially urgent for these communities.

“This research is a stark reminder that we cannot continue with business-as-usual with respect to plastic pollution,” she said. “The animals we studied are so much more than just beautiful and fun to look at. They all play important ecological roles in the ocean and for many communities, including those across the Pacific.”

Murphy noted that plastic pollution affects species that hold cultural meaning throughout Oceania, including green sea turtles, frigatebirds and sperm whales.

Murphy said the study offers governments, conservation groups and negotiators

clearer evidence about which plastics pose the highest risks. She hopes it strengthens policy conversations, especially as global talks continue around plastic production and waste.

“To solve this problem, the science is clear: We need to reduce the amount of plastics we produce, improve collection and recycling, and clean up what’s already out there,” she said.

Ocean Conservancy, she added, has mobilized more than 19 million volunteers worldwide since 1986 to collect more than 400 million pounds of trash. The data helps identify which products are most frequently found on coastlines.

 “Entanglement also causes death in all three animal groups and may be even more deadly than ingestion,” Murphy said. Her team hopes to combine both datasets to offer a more complete picture of the risks.

Regions that face high exposure to plastic pollution, including many Pacific island nations, could benefit from localized studies. Murphy said future research could map the areas and species most affected in the Pacific and identify the most harmful items washing ashore.

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