Effects of Microplastics on Seabird Chicks: An Experiment Using Pellets with and Without Chemical Additives

Microplastics ingested by seabirds may decrease digestive ability, increase stress levels, and cause lesions in their digestive tracts. Hazardous chemicals added to and accumulated in these plastics may also pose adverse effects. To examine these effects, two experiments were carried out using wild Streaked Shearwater Calonectris leucomelas chicks. We dosed them orally with either 0.43 g plastic pellets with chemical additives (flame retardant and UV stabilizer), or 2.00, 3.00 and 4.00 g virgin plastic pellets without additives. The dose of pellet loads of up to 0.8% of chick body mass did not affect growth in body mass, structural size, meal mass per day, or plasma stress hormone levels. Pellets with chemical additives, however, appeared to adversely affect liver and kidney masses during their early development, raising the concern of potential toxic effects of chemical additives within the microplastics themselves, in the stomachs of seabirds.