Decades of monitoring plastic pollution in seabirds in Canada: Spatial, temporal, and methodological insights.

Plastic ingestion by seabirds is an increasing issue worldwide, yet species can vary in ingestion based on ecological and morphological differences. This provokes the ecological question of which species are better suited to monitor plastic ingestion across regions and time. In Canada, we examined plastic ingestion in sympatric northern fulmars (Fulmarus glacialis), black-legged kittiwakes (Rissa tridactyla), thick-billed murres (Uria lomvia), and black guillemots (Cepphus grylle). Here, we present new data and compare to historical work to inform plastic pollution monitoring in Canada. In 2021, 51 % of fulmars, 7 % of kittiwakes and 7 % of murres contained plastic, whereas guillemots had no pieces >1 mm. Regardless of the methods used to collect and process samples, fulmars continue to have low levels of ingestion compared to the European Arctic, but high levels compared to other species in the Canadian Arctic, emphasizing their continued utility as a monitoring tool for plastic pollution in Canada.

The relationship between plastic ingestion and trace element concentrations in Arctic seabirds.

Seabirds ingest contaminants linked to their prey's tissues, but also adsorbed to ingested plastic debris. To explore relationships between ingested plastics and trace elements concentrations, we analyzed 25 essential non-essential trace elements in liver tissue in relation to plastic content in the gastrointestinal tract in adults of four species of Arctic seabirds with different propensity to ingest plastic. Linear Discriminant Analysis (LDA) provided a clear separation between species based on element concentrations, but not among individuals with and without plastics. Molybdenum, copper, vanadium, and zinc were strong drivers of the LDA, separating northern fulmars (Fulmarus glacialis) from other species (60.4 % of explained between-group variance). Selenium, vanadium, zinc, and mercury were drivers separating black-legged kittiwakes (Rissa tridactyla) from the other species (19.3 % of explained between-group variance). This study suggests that ingestion of plastic particles has little influence on the burden of essential and non-essential trace elements in Arctic seabird species.