Evaluation of microplastics and metal accumulation in domestic ducks (Anas platyrhynchos f. domesticus) of a contaminated reservoir in Central Mexico

We procured a total of 22 Anas platyrhynchos f. domesticus (domestic ducks) individuals around the Valsequillo Dam, Puebla, Mexico, to assess ingested plastics and accumulated metals (As, Ba, Cd, Cr, Cu, Hg, Ni, Pb, Zn). The morphometric results of all the samples presented adverse body conditions, where the females had less average body weight (1.94 ± 0.30 kg), height (53. 7 ± 2.78 cm) and wingspan length (92.6 ± 7.45 cm) compared to the male species. The coefficients of variation of all the studied elements (CV > 36 %), except Cu in feathers, demonstrated a high degree of variation, implying exogenous contamination from human activities. Nearly all the studied species presented MP ingestion, with an average of 154.9 suspected particles/ individual. The colour of the MPs was mainly blue (35 %) and transparent (32 %), while the principal forms of MPs were fragments (53 %) and filaments (36 %). The SEM-EDX characterization presented carbon and oxygen peaks and affirmed that the extracted particles are polyethylene and polypropylene. The Pollution Load Index values for MPs were found to be >1, signifying that the site is polluted by MPs, and the calculated Potential Risk Index denoted that the ducks are at low risk of exposure to Cd, Cr, Zn and Ni, and a constant exposure to Cu can be harmful. The study will contribute to establishing baseline data to elucidate the degree of accumulation of MPs and metals in domestic ducks which will be used to employ monitoring programs for the sustainable conservation of the aquatic ecosystem.