Demographic Differences in the Quantity, Mass, and Anatomical Location of Ingested Plastic in Northern Fulmars (Fulmarus glacialis): A Review and Reconsideration of NE Pacific Ocean Samples

On the Washington and Oregon coast of the NE Pacific Ocean from 2008-2015, we found that juveniles represented 83% of Northern Fulmars that were beached. In comparison to older birds, juveniles averaged more mass and pieces of plastic in stomachs. This reflected relatively larger plastic loads in the cranial stomach section, the proventriculus, which we found was associated with relatively large accumulations in the caudal stomach section, the ventriculus. We estimate that the proventriculus could retain almost 10 times as much plastic as the ventriculus and that retention of proventricular plastic largely accounted for the difference in juveniles versus older birds. Our findings contrast with published Atlantic Ocean reports where the proportion of immatures was lower and plastic was retained mostly in ventriculi. The differences in demography and gastric distribution between NE Pacific and Atlantic fulmars may reflect the different sizes of plastic particles that were available. The preponderance of juveniles in NE Pacific Ocean samples and associated relatively large plastic loads overestimate the load for the species. Without accounting for age and gastric distribution, comparison to other regions is ill-advised. An unrecognized complication in stomach-based sampling is that differences in size of plastic at spatiotemporal scales could affect the utility of stomach samples as bioindicators of oceanic plastic pollution.

Polymer types ingested by northern fulmars (Fulmarus glacialis) and southern hemisphere relatives

Although ingestion of plastic by tubenosed seabirds has been documented regularly, identification of the polymer composition of these plastics has rarely been described. Polymer assessment may assist in identifying sources and may indicate risks from additives occurring in specific types of polymers. Using known test materials, two identification methods Fourier transform infrared spectroscopy and near infrared spectroscopy (FTIR and NIR) were compared. Although both methods were found to be similarly suitable for identification of plastic polymers, a significant difference was observed in identification of natural materials. FTIR frequently misclassified natural materials as being a synthetic polymer. Within our results, an 80% match score threshold functioned best to distinguish between natural items and synthetics. Using NIR, the historical variability of plastics ingested by northern fulmars (Fulmarus glacialis) from the Dutch sector of the North Sea was analysed for three time periods since the 1980s. For the more recent decade, variability between fulmars from different regions in the northeast Atlantic was investigated. Regional variation was further explored by analysing plastics obtained from the stomachs of southern hemisphere relatives of the fulmar (southern fulmar, cape petrel, snow petrel) and Wilson’s storm petrel. Results show that proportional abundance of polymer types in these seabirds is closely related to the plastic categories that they ingest (e.g. pellets, foam, fragments). The uptake of different plastic categories and related polymer types most likely reflects spatial and temporal variations in availability rather than ingestion preferences of the birds.