Contaminação por resíduos plásticos em boto-cinza (Sotalia guianensis) no litoral do Ceará, Brasil

Abstract

Marine mammals, as top marine predators, are considered sentinel species and may act as indicators of ocean health. Plastic residues are widely distributed in the oceans and are already recognised as hazardous contaminants. Once ingested, plastic residues can cause several adverse effects on wildlife, depending on the particle size and incidence. This study aimed to identify and characterise plastic ingestion (macro - microplastic) in the Guiana dolphins (Sotalia guianensis) from the Tropical Southwestern Atlantic by evaluating the stomach contents of a 10-year sampling retrospective. Plastic residues were extracted through KOH digestion and a subsample of particles was identified by LDIR Chemical Imaging System. Most of the individuals evaluated (38 out of 40) were contaminated, the most common polymers identified were PU, PET and EVA. Microplastics (7.77 ± SE 1.25 particle individuals-1) were more prevalent than larger plastic particles (0.15 ± 1.25 part. ind.-1). The interannual variability did not influence either the size or number of microplastics ingested. However, smaller particles were detected during the rainy seasons. There was a positive correlation between the stomach content mass and the number of microplastics, suggesting contamination through trophic transfer.