A baseline characterization of microplastic occurrence in the water column and zooplankton and ichthyoplankton of Saint John Harbour, New Brunswick

Microplastics (MPs) are ubiquitous in the ocean. Regional assessments are necessary to characterize baseline MP levels, to monitor temporal change, and evaluate ecological risk. We conducted a multi-year survey of MPs present in seawater and ingested by zooplankton and ichthyoplankton in Saint John Harbour, Bay of Fundy, Canada. Microlitter was found in all seawater samples and ingested by 94% of zooplankton taxa. The majority of microlitter particles found were blue or black fibres. Fourier transform infrared spectroscopy (FTIR) analysis showed that 62% of particles were cellulose, while only 18% were classified as MPs. Larval fish species had some of the highest MP encounter rates. Of the copepod taxa, Calanus sp. had the highest MP encounter rate. This study is the first to characterize MPs and other microlitter in the water column and zooplankton community in Saint John Harbour and serves as a baseline to which further analyses can be compared.