Quantifying microplastic ingestion, degradation and excretion in insects using fluorescent plastics.

Plastic pollution is a growing threat to our natural environment. Plastic waste/pollution results from high emissions of both macro (>5 mm) and microplastics (MPs; <5 mm) as well as environmental fractioning of macroplastics into MPs. MPs have been shown to have a range of negative impacts on biota. Harmonized methods to accurately measure and count MPs from animal samples are limited, but what methods exist are not ideal for a controlled laboratory environment where plastic ingestion, degradation and elimination can be quantified and related to molecular, physiological and organismal traits. Here, we propose a complete method for isolating and quantifying fluorescent MPs by combining several previously reported approaches into one comprehensive workflow. We combine tissue dissection, organic material digestion, sample filtering and automated imaging techniques to show how fluorescently labelled MPs provided to insects (e.g. in their diet) in a laboratory setting can be isolated, identified and quantified. As a proof of concept, we fed crickets (Gryllodes sigillatus) a diet of 2.5% (w/w) fluorescently labelled plastics and isolated and quantified plastic particles within the gut and frass.

No accumulation of microplastics detected in western Canadian ringed seals (Pusa hispida).

Ringed seals (Pusa hispida) play a crucial role in Arctic food webs as important pelagic predators and represent an essential component of Inuvialuit culture and food security. Plastic pollution is recognized as a global threat of concern, and Arctic regions may act as sinks for anthropogenic debris. To date, mixed evidence exists concerning the propensity for Canadian Arctic marine mammals to ingest and retain plastic. Our study builds on existing literature by offering the first assessment of plastic ingestion in ringed seals harvested in the western Canadian Arctic. We detected no evidence of microplastic (particles ≥80 µm) retention in the stomachs of ten ringed seals from the Inuvialuit Settlement Region (ISR) in the Northwest Territories, Canada. These results are consistent with previous studies that have found that some marine mammals do not accumulate microplastics in evaluated regions.

Microplastics around an Arctic seabird colony: Particle community composition varies across environmental matrices.

Plastic pollution is a contaminant of global concern, as it is present even in remote ecosystems - like the Arctic. Arctic seabirds are vulnerable to ingesting plastic pollution, and these ingested particles are shed in the form of microplastics via guano. This suggests that Arctic seabird guano may act as a vector for the movement of microplastics into and around northern ecosystems. While contaminant-laden guano deposition patterns create a clear concentration gradient of chemicals around seabird colonies, this has not yet been investigated with plastic pollution. Here we tested whether a contaminant gradient of plastic pollution exists around a seabird colony that is primarily comprised of northern fulmars (Fulmarus glacialis) in the Canadian Arctic. Atmospheric deposition, surface water, and surface sediment samples were collected below the cliff-side of the colony and at increasing intervals of 1 km from the colony. Fulmars were also collected when foraging away from their colony. Microplastics and other anthropogenic microparticles were identified in all three environmental matrices as well as fulmar guano. Fibers were the most common shape in fulmar guano, atmospheric deposition and surface sediment, and fragments were the most common shape in surface water. We did not find a gradient of microplastic concentrations in environmental matrices related to distance from the colony. Combined, these results suggest that fulmars are not the primary source of microplastic around this colony. Further research is warranted to understand sources of microplastics to the areas around the colonies, including to what extent seabirds transport and concentrate microplastics in Arctic ecosystems, and whether concentrations proximate to large colonies may be species dependent.

Breeding seabirds as vectors of microplastics from sea to land: Evidence from colonies in Arctic Canada.

The presence and persistence of microplastics in the environment is increasingly recognized, however, how they are distributed throughout environmental systems requires further understanding. Seabirds have been identified as vectors of chemical contaminants from marine to terrestrial environments, and studies have recently identified seabirds as possible vectors of plastic pollution in the marine environment. However, their role in the distribution of microplastic pollution in the Arctic has yet to be explored. We examined two species of seabirds known to ingest plastics: northern fulmars (Fulmarus glacialis; n = 27) and thick-billed murres (Uria lomvia; n = 30) as potential vectors for the transport of microplastics in and around breeding colonies. Our results indicated anthropogenic particles in the faecal precursors of both species. Twenty-four anthropogenic particles were found in the fulmar faecal precursor samples (M = 0.89, SD = 1.09; 23 fibres and one fragment), and 10 anthropogenic particles were found in the murre faecal precursor samples (M = 0.33, SD = 0.92; 5 fibres, 4 fragments, and one foam). Through the use of bird population surveys and the quantification of anthropogenic particles found in the faecal precursors of sampled seabirds from the same colony, we estimate that fulmars and murres may deposit between 3.3 (CIboot 1.9 × 106-4.9 × 106) and 45.5 (CIboot 9.1 × 106-91.9 × 106) million anthropogenic particles, respectively, per year into the environment during their breeding period at these colonies. These estimates indicate that migratory seabirds could be contributing to the distribution and local hotspots of microplastics in Arctic environments, however, they are still likely a relatively small source of plastic pollution in terms of mass in the environment and may not contribute as much as other reported sources such as atmospheric deposition in the Arctic.

No plastics detected in seal (Phocidae) stomachs harvested in the eastern Canadian Arctic.

Through collaboration with Inuit hunters, we examined the stomach contents of 142 seals (ringed seals [Phoca hispida; n = 135], bearded seals [Erignathus barbatus; n = 6], and one harbour seal [Phoca vitualina; n = 1]) hunted between 2007 and 2019 from communities around Nunavut to assess whether seals in the eastern Canadian Arctic ingest and retain plastics in their stomachs. The seals in this study ranged from juveniles to adults of up to 30 years of age, and 55% of the seals were males. We found no evidence of plastic ingestion in any of the seals suggesting that seals in Nunavut are not accumulating plastics (>425 µm) in their stomachs. These data provide important baseline information for future plastic pollution monitoring programs in the Arctic.