Microplastics (particles less than 5 mm in size) are increasingly seen as a global environmental concern, having been detected in multiple aquatic species and in environments around the world.
However, very little is known about the presence of microplastics in marine mammals, largely reflecting the legal, ethical and logistical challenges associated with this line of research.
In a new study, led by Ocean Wise, researchers worked with community-based monitors and Inuvialuit hunters from Tuktoyaktuk (Northwest Territories, Canada) to sample seven beluga whales in 2017 and 2018.
Microplastics were detected in the gastrointestinal tracts in every individual whale, with each whale having an average of nearly 10 particles.
Subsequent polymer identification through the application of FTIR-spectroscopy confirmed over eight plastic polymer types, with nearly half being polyester. Fibres made up 49% of microplastics. The diversity of microplastic shapes and polymeric identities in beluga points to a complex source scenario, and ultimately raises questions regarding the implications for the health of this ecologically and culturally valuable species.
Rhiannon Moore, MSc researcher at Ocean Wise and lead author of the study said, “While we increasingly recognize the near-ubiquitous nature of microplastics in the world’s oceans, I admit to being surprised – and saddened – to find microplastics in each and every whale we sampled”.
This study fills a notable gap in our understanding of microplastic transport and fate in the Arctic, as it represents the first report of microplastics in a marine mammal in Canada’s North and the most comprehensive evaluation in the world for such a species.
Dr. Peter Ross, VP Research at Ocean Wise and co-author on the study reflects that “The further we work to track microplastics in the ocean, the more we realize the truly global nature of microplastic pollution and the insidious way in which they get into wildlife”.
The Ocean Wise-led team is now focused on tracking microplastics in the prey of beluga so as to provide additional insight into the pathways of microplastic transport in this remote region. The involvement of Department of Fisheries and Oceans and the Inuvialuit community of Tuktoyakuk, have been instrumental in the launch and success of this research.
This study represents the first-ever report on microplastics in a marine mammal in Canada, and the most comprehensive study of its kind in the world.
Microplastic particles were found in all seven belugas investigated, within both the intestines and the stomach of every individual.
The study estimates that the entire GI tract of the belugas contain an average of nearly 100 particles. 9 different types of plastic polymers were identified, with polyester dominating.
While pathways remain unclear, the researchers suspect that these belugas are ingesting microplastics through the fish and invertebrates they feed on.
Researchers continue their work by tracking microplastics through the food web of these beluga whales.