Shorebird droppings analysis: Microplastics and heavy metals in a key conservation reserve and adjoining sand beaches in the west coast of India

Coastlines are susceptible to plastic and heavy metal pollution, which can accumulate from both marine and terrestrial sources. Shorebirds, top-level predators in these fragile ecosystems are considered as indicators of environmental health. Here, we tested the occurrence of microplastics and heavy metals in the droppings of ten regular wintering migrant shorebird species in Kadalundi-Vallikkunnu Community Reserve and adjoining sand beaches during November, December and January, each year, between 2019 and 2021. Heavy metals were analysed by Flame Atomic Absorption Spectrophotometer and the microplastic polymer compositions were identified using ATR-FTIR spectroscopy. We detected high concentrations of heavy metals such as Zinc, Copper, Cobalt, Chromium, Lead and Cadmium in droppings. Polyethylene, Polypropylene, Polystyrene, Poly Vinyl Chloride, Nitrile and Polyethylene terephthalate were the polymers identified. Polystyrene (42.6 %) and chromium (ranges between 7.83 and 88.45 mg/kg) were found to be the most abundant contaminants in most of the species.