Plastic ingestion in short-tailed shearwaters significantly reduces BDNF levels, potentially impairing cognitive functions essential for courtship and breeding success.
Plastic ingestion in short-tailed shearwaters significantly reduces BDNF levels, potentially impairing cognitive functions essential for courtship and breeding success.iStock

Plastic pollution killing seabirds: Study links ingestion to multi-organ failure, brain damage

Scientists discover 403 plastic fragments in a single 90-day-old chick, linking ingestion to neurodegenerative disease similar to Alzheimer’s
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Plastic pollution is causing a health crisis in seabirds, according to a new study. which found that ingesting plastic causes neurodegeneration similar to Alzheimer’s in chicks as young as 90 days old. The study, published in the journal Science Advances, also discovered that chicks had cell rupture and multi-organ failure, affecting the stomach, liver, brain and kidneys. 

Researchers from the University of Tasmania analysed short-tailed shearwaters (Ardenna tenuirostris), a marine wildlife species from Lord Howe Island, Australia, between 2022 and 2024.

Describing the findings as alarming, scientists who studied seabird chicks under 90 days old reported that their health was heavily compromised. The chicks ingested plastic through their parents, as they had not yet left the nest.

The research also found evidence of amyotrophic lateral sclerosis (ALS), a neurodegenerative disorder that leads to the progressive degeneration of motor neurons in the brain and spinal cord.

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Plastic ingestion in short-tailed shearwaters significantly reduces BDNF levels, potentially impairing cognitive functions essential for courtship and breeding success.

“Despite the absence of visible signs of ingesting high quantities of plastic, this study revealed significant differences in the proteomes of free-living sable shearwaters with low and high levels of plastic ingestion,” the study said.

The scientists identified the stomach as the initial site where macroplastic particles accumulated. Their analysis showed that the stomach lining had decayed, compromising its permeability.

In one sample, researchers removed 403 pieces of plastic from a 90-day-old chick.

Four hundred three plastic pieces were removed from a 90-day-old sable shearwater chick.
Four hundred three plastic pieces were removed from a 90-day-old sable shearwater chick.Science Advances

Blood tests revealed that chicks with high levels of ingested plastic had reduced levels of critical blood proteins predominantly produced by the liver, including albumin, complement proteins and coagulation proteins. “Conversely, intracellular liver proteins were increased in the plasma, including proteins such as alcohol dehydrogenase and aldehyde dehydrogenase,” the research stated.

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Plastic ingestion in short-tailed shearwaters significantly reduces BDNF levels, potentially impairing cognitive functions essential for courtship and breeding success.

This suggests that uncontrolled cell death through necrosis is occurring within the liver, the researchers noted.

They also found protein signatures linked to neurodegenerative diseases among chicks with high plastic ingestion. The study reported a significant decline in brain-derived neurotrophic factor (BDNF), which is crucial for the growth, survival and functioning of neurons.

In birds, BDNF is associated with the development of the song control system. Although chicks ingesting large amounts of plastic were unlikely to survive into adulthood, a reduction in BDNF could impact cognitive functions necessary for courtship. This, in turn, could affect breeding success among the comparatively healthier birds.

For shearwaters and other colonial breeding birds, fine-scale acoustic cues are essential for effective communication between lifelong pairs in large noisy nocturnal colonies, the paper stated

“Male-female reunion requires identification of the call of the opposite sex and individual mate recognition. Interruption of the development of song control and the ability to dis- criminate sound could have considerable implications for fitness, particularly in long-lived species exposed to plastic,” the study observed.

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Plastic ingestion in short-tailed shearwaters significantly reduces BDNF levels, potentially impairing cognitive functions essential for courtship and breeding success.

Birds exposed to high plastic ingestion produced lower plasma levels in their kidneys, the research stated.

Summarising their findings, the researchers stated, “This study has shed light on the complexity of sublethal health consequences that otherwise remain invisible. Metrics commonly used within ecology for assessing body condition may be an ineffective tool for accurately documenting the impacts of plastic on populations.”

The research demonstrated that plastic ingestion affects not just the stomach but also multiple vital organs. The proteomic signatures of cell lysis, multi-organ failure and neurodegeneration observed in seabird chicks under 90 days old clearly indicate that their health was severely compromised, the study concluded.

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