Effects of Plastic Ingestion on Blood Chemistry, Gene Expression and Body Condition in Wedge-Tailed Shearwaters (Ardenna Pacifica)

Abstract

Plastic pollution is a global threat and affects almost every marine ecosystem. The amount of plastic in the ocean has increased substantially over the past decade, posing a mounting threat to biodiversity. Seabirds, typically top predators in marine food chains, have been negatively affected by plastic pollution. Here we focused on documenting the sublethal effects of plastic in Wedge-tailed Shearwaters (Ardenna pacifica, WTSH) on the island of Maui, Hawaii. Through analyses of blood chemistry, gene expression, morphometrics and stomach contents, we documented the effects of plastic ingestion on adult WTHS from 3 established colonies. We detected a negative relationship between body weight and the presence of plastic in regurgitated stomach contents. Genes associated with metabolic, biosynthetic pathways, inflammatory responses and ribosome function were upregulated in lighter birds. Birds that had ingested plastic tended to be lighter in weight, in comparison to birds that did not have plastic and tended to weight more. Furthermore, there were 43 genes differentiating males and females that did not have plastic compared to only 11 genes differentiating males and females that had ingested plastic. There was also a marginal negative relationship between lighter birds and blood urea nitrogen levels. We also hope that the morphometric measurements, blood parameters and gene expression data we collected contributes to a database that will be used for future studies on understanding anthropogenic effects on seabird body condition.