Parasites and plastics in seabirds of the North Pacific

Background/Question/Methods

Pelagic communities are experiencing shifts in their connectivity, biomass, and species compositions as humans alter abiotic and biotic components of their ecosystems. Seabirds are sentinels of ecosystem change, representing large-scale consumers, foraging over great geographic areas through time. Some seabirds, like Procellariiformes, are known to forage over tens of thousands of km2 in a day. In doing so, seabirds have opportunities to encounter highly nutritionally valuable prey and to interact with synthetic, non-prey items. In many cases, non-prey are pieces of plastic that have fragmented and are easily consumed. Consequently, the Procellariiformes are well-known for consuming marine debris. Many of the familiar cases of seabird mortality associated with marine debris include interactions with macroplastic pieces (>5mm length); however, microplastics (<5mm length) are more abundant and are consumed more frequently. Depending on the seabird, its morphology, and its behavior, the impact of microplastics can range from negligible (plastics pass through GI easily) to complete blockage and/or injury that results with starvation and death. Here, we document and describe the plastics consumed by Northern Fulmars (Fulmarus glacialis) collected in the North Pacific waters of Alaska. We an index specific to fulmars to better understand the pollution levels in areas where they were collected. In addition to plastic pollution, many birds were found to be consuming typical dietary items for the species and we also document the parasite communities that they contained as a result of these trophic connections. While consuming prey items, seabirds can acquire parasites, many of which are specific to the intermediate or avian host that they infect. Northern Fulmars are documented as having a relatively low richness of parasites worldwide and we test whether there is a connection between the richness, abundance, and biomass of parasites and the quantity of consumed plastics.

Results/Conclusions

We find that plastics are regularly consumed by Northern Fulmars, and that the majority of birds with plastics in their stomachs exceed the fulmar index of 0.1g plastic. Our helminth community assessments corroborate the historical reports for a paucity of parasite species infecting these seabirds. Most birds were infected by 3 or fewer species of a combination of nematode and cestodes. We did not find a relationship between plastic and parasite metrics. Despite increasing their dietary breadth to include non-traditional prey items, it appears that fulmars are not being successfully infected by new species of helminthic parasites, nor do consumed plastics appear to be reducing parasite richness.