Blood tests in petrels show unknown effects on plastic pollution

Amsterdam, 05 November 2019 – Australian researchers have looked at the effect of plastic on seabirds. It has long been known that seabirds ingest plastic that causes blockages or suppresses the feeling of hunger. But are there other factors involved? A recent publication analyses, among other things, the effect of plastic on the blood levels of young seabirds.

Hidden effects

The ingestion of plastic has some very clear and direct consequences for seabirds. For example, plastic can cause digestive blockages and malnutrition. Often a relation is made between the size and mass of the animal and plastics found in the stomach. However, there are also factors of importance that are less visible. Plastics can release toxic chemicals and microplastics can have a negative effect on the digestion of food because they lead to higher concentrations of uric acid, among other things.


As these factors are more difficult to measure, the negative effects of plastic are probably underestimated. Analyzing blood values offers a solution to this problem. The new research focuses specifically on the Australian Shearwater, a seabird that spends a lot of time at sea. The same researchers reported earlier that this species receives the most plastic of all vertebrates in and at sea.

Blood tests

The new research shows clear links between the amount of plastic and some blood levels of the young petrels. More plastic appears to be associated with a lower level of calcium in the blood. This may indicate, among other things, lower fat reserves, reduced absorption of nutrients, thyroid problems and pancreatitis. In addition, the research points to increased values for cholesterol, the amylase enzyme, and uric acid, related to malnutrition, long-term stress, and kidney failure. Finally, it appears that birds with plastic in their stomachs have a significantly lower weight and are smaller in size. The researchers emphasize that these blood levels and the effects are part of a complex system, in which general living conditions also play a role.

More complete picture

The new study provides insight into the hitherto ‘hidden’ effects of plastic intake by seabirds. The researchers argue that the less visible effects of plastic pollution should also be shown.

Read more – Plastic chemicals in petrel eggs