Microplastics in the diet of nestling double-crested cormorants (Phalacrocorax auritus), an obligate piscivore in a freshwater ecosystem

Abstract

Anthropogenic debris, namely plastic, is a concern across aquatic ecosystems worldwide, with freshwater systems being understudied relative to marine systems. In this study, we quantified and characterized debris in the diet of double-crested cormorant chicks (Phalacrocorax auritus) from three sites in two of the Laurentian Great Lakes to (i) determine whether or not the diet of double-crested cormorants in the Laurentian Great Lakes includes anthropogenic debris, (ii) characterize the size, shape, and type of debris incorporated, and (iii) examine relationships between the amount of debris ingested and their proximity to industrial–urban centres. Overall, >86% of cormorants in our study had anthropogenic debris (mostly fibers) in their digestive tracts with no correlation between site and the amount of debris ingested. The ingested debris includes microplastics, natural fibres from textiles, and other anthropogenic materials (e.g., glass). To the best of our knowledge, this is one of the first studies to examine anthropogenic debris in a diving bird in the Laurentian Great Lakes and one of few studies investigating this in freshwater birds.