Investigating microsized anthropogenic particles in Norwegian fjords using opportunistic nondisruptive sampling

Abstract Norwegian fjord systems provide a host of ecosystem services and are important for recreational and industrial use. The biodiversity of Norwegian fjords has been—and still is—extensively studied since they are important for fishing and aquaculture industries. However, threats from plastic and microplastic pollution within the fjord systems are largely undocumented. Monitoring efforts of microplastic in Norway are limited to coastal biota monitoring, offshore sediments, and some investigations within Oslofjord. Here, we quantify anthropogenic microparticles in Norwegian fjord subsurface waters, including an analysis of distribution effects. Fifty-two samples were collected during repeated transits from Bergen to Masfjorden covering 250 km. Anthropogenic particles were identified in 89% of samples, with an average abundance within the fjord estimated to be 1.9 particles m −3 . This report shows the ubiquitous nature of anthropogenic particles in the subsurface waters of a Norwegian Fjord system. Additionally, methods were validated for opportunistic nondisruptive sampling on-board vessels where microplastics are seldom monitored, including research vessels, commercial freight and transport, and recreational vessels. Further development and implementation of these methods in terms of sampling, chemical characterisation, and long-term monitoring will allow for microplastic quantification and can be easily adapted for worldwide implementation.