Abstract
Microplastics (MPs) have emerged as widespread and persistent environmental pollutants, posing a threat to biodiversity, particularly for vulnerable species such as the American crocodile (Crocodylus acutus). As an apex predator with constant exposure to aquatic environments, C. acutus holds potential as a bioindicator of microplastic contamination. This study assessed microplastic ingestion in the stomach contents of eighteen individuals from the Punta Sur Ecological Reserve, Cozumel, Mexico. Physical characterization of MPs was performed through stereoscopic and microscopic observation, while polymer composition was identified using Fourier-transform infrared spectroscopy (FTIR). Microplastic abundance ranged from 0 to 39 items ind⁻¹, with a mean abundance of 10.4 ± 11.7 items ind⁻¹. The most frequently observed morphotype consisted of yellow fragments measuring 2–5 mm. Among the eighteen polymers identified, ethylene propylene diene monomer (EPDM) was the most abundant, which may suggest a localized contamination source; its prevalence may also be associated with its high environmental persistence and resistance to weathering, ozone, and UV radiation. The Polymer Hazard Index (PHI) revealed that polyvinyl chloride (PVC), polyvinylidene chloride (PVDC), and polyacrylonitrile (PAN) pose an elevated risk to exposed organisms. This study provides the first evidence of microplastic ingestion in Crocodylus acutus in Mexico. The detection of MPs in individuals inhabiting a protected coastal ecosystem highlights the presence of plastic contamination even within conservation areas. These findings provide baseline information on microplastic exposure in a top predator and contribute to improving the current understanding of plastic pollution in coastal ecosystems.
•First evidence of microplastic ingestion in Crocodylus acutus from Mexico.•Microplastic detected in stomach contents of wild crocodiles from a protected wetland.•Microplastic abundance ranged from 0 to 39 items ind−1.•Identified polymers included EPDM, alkyd resin, and PVDF•Crocodylus acutus shows potential as a bioindicator of coastal plastic pollution.
