by Lauren Frisch
University of Alaska researchers are measuring concentrations of plastic-related chemicals in seabirds on remote western Aleutian Islands. These chemicals could be one explanation for a major decline in seabird populations that has occurred over the past few decades.
“We wanted to find out if a change in diet had anything to do with the population declines,” said Veronica Padula, a PhD student in a joint program with the University of Alaska Fairbanks College of Fisheries and Ocean Sciences and the University of Alaska Anchorage. “But when we found microplastics inside the seabirds, the scope of our project evolved to focus on the impacts that might have on seabird populations.”
The researchers chose western Aleutian bird populations for their study because they are isolated from human populations. From Adak, Alaska, it’s still about a forty-hour steam in a research vessel to get to the western tip of the Aleutians. Currently, there are no human communities this far out.
But these birds have seen major declines in recent decades. “There were about 90,000 Red-faced Cormorants in Attu when I first started working there in the 1970s,” said University of Alaska Anchorage researcher Douglas Causey. “When I went there in 2016, we worked hard to see 200 of them.”
Because the seabird populations are so isolated, understanding what is causing the numbers to decline may reveal a lot about larger-scale environmental change. There are no direct human stressors on these bird populations. Changes to the population could be triggered by a number of factors including climate change, increasing exposure to chemicals, or changes in food source.
“At first we were looking at what the seabirds were eating using stable isotope analysis,” said Padula. “But when we started opening up their stomachs, we found plastics inside our birds. And we thought ha! This is weird. It was not on our radar. It really was not what we were expecting to find.”
It can be very obvious when certain seabirds are exposed to plastics, Padula explained. If birds consume big or awkwardly shaped plastic, it can fill up their stomachs and lead to starvation. This has affected albatross populations in Hawaii. Additionally, gannets in the British Isles got tangled trying to create their nests out of fishing lines, which was also very visible.
“But this was not the case with Aleutian seabirds,” Padula explained. “There was no evidence of physical trauma caused by consumption or use of plastics.”
Unlike gannets and albatross, seabirds in the Aleutians have been exposed to tiny pieces of plastic called microplastics. In many cases, the plastic pieces pass through the animals’ systems. Even if the plastic did not pass through, the pieces are so small that it would take a long time for the animal to consume enough to fill its stomach and lead to starvation.
Padula, Causey and their team became interested in investigating why it might matter that the western Aleutian seabirds are consuming the microplastics, and if this could be leading to the decline in population numbers over the past few decades. Their research is funded by the Experimental Program to Stimulate Competitive Research, United States Geological Survey Climate Science Center, Idea Network of Biomedical Research Excellence, Alaska Maritime National Wildlife Refuge, Conoco Phillips Endowment Grant, and the LGL scholarship at the University of Alaska Anchorage.
The scientists joined forces with the Applied Science, Engineering and Technology lab at the University of Alaska Anchorage, an analytical chemistry lab down the hall that focuses on studying contaminants in environmental samples. The chemists offered to search Padula’s birds for phthalates, which are plastic-associated chemicals.
While roughly one-fourth of the birds had plastics in their stomachs at the time that they were collected, the chemists tested tissues from collected birds with and without visually detectable plastic inside.
“Regardless of whether or not they had plastic in their stomachs, more often than not the birds had phthalates in their tissues,” Padula said. “This signals to us that at some point in the bird’s life, either it got exposed to plastic or ate something that had been exposed, transferring those chemicals.”
Padula hopes these results will motivate additional research projects that dig deeper into how phthalates may be impacting Aleutian seabirds. At certain levels, phthalates are associated with higher levels of infertility, cancer and early puberty in humans. Although this could be the case in seabirds as well, researchers don’t have the background information or a good measure for a dangerous level of exposure in birds.
This sheds light on the far-reaching implications of the human impact, said Padula. Phthalates are manufactured by humans, and are traveling thousands of miles in the ocean to the birds of the western Aleutians.
“Whatever the broader impacts are for the population, it hits me personally that this should not be happening in the first place,” Padula said. “We do not live in a bubble, and all of our actions affect the environment around us.”