TOXICITY INDUCED BY INGESTION OF NATURALLY-AGED MICROPLASTICS BY A SMALL-SIZED TERRESTRIAL BIRD AND ITS POTENTIAL ROLE AS VECTORS FOR THE DISPERSION OF THESE POLLUTANTS

Abstract

In recent years, there has been a growing number of studies on the impact of microplastics (MPs) on biota. However, its effects on bird health are poorly understood. Thus, we aimed to evaluate the possible effects of ingestion of naturally-aged MPs by Coturnix coturnix japonica (11 and 22 MP particles/day/bird, once a day, for 9 days), from different toxicity biomarkers. At the end of the experiment, our data showed that birds that ingested MPs showed a significant reduction in body biomass. We also observed an increase in malondialdehyde production in the liver, brain, intestine, and gizzard of the animals, as well as a suppressive effect on hepatic nitric oxide production and superoxide dismutase activity in the liver and intestine. Cerebral catalase activity was reduced in birds exposed to MPs and a cholinesterasic effect (marked by increased acetylcholinesterase activity) was observed in the muscle and brain of these animals. Despite these differences, through the main component analysis, hierarchical clustering analysis, and integrated biomarker response assessment, we observed that, in general, the toxicological effect in birds exposed to different amounts of MPs was similar. We also noticed that the size of MPs was reduced, and their shape was altered as they transited through the gastrointestinal system, which probably explains their accumulation in the liver of birds. In addition, we noticed that expressive amounts of MPs are released by the feces of the animals throughout the experiment. As far as we know, this is the first report that associates MPs ingestion by small-sized terrestrial birds with biochemical alterations predictive of oxidative stress, redox imbalance, and cholinesterase effect, in addition to shedding light on the potential role of these birds as vectors for dispersal of MPs in natural environments.