The extent of marine litter and microplastic occurrence across ocean biomes and species remains poorly characterised, particularly in remote deep-water ecosystems. The present study in the East Mingulay Special Area of Conservation (a Marine Protected Area in the Sea of the Hebrides, western Scotland) used historic surveys and benthic samples to obtain baseline levels of anthropogenic debris and microparticle ingestion. Most debris identified in the MPA was fisheries-related. A total of 11% of benthic macrofauna from Mingulay Reef Area 1 and Banana Reef had ingested microplastics, with no statistically significant effect of feeding guild, station, or reef, on ingestion rates. However, the ingestion rate was highest at a station located in a topographic hollow along a gentle sloping area with strong variable ocean currents where fine-scale interactions between bathymetry and hydrography may have helped trap and focus microparticles. Raman spectroscopy of microparticles revealed several types of polymers being ingested, tentatively identified as polypropylene (PP), polyurethane (PU), polystyrene (PS), and polyethylene terephthalate (PET). Besides establishing a baseline assessment of marine litter and microparticles in a deep-water setting, the approach demonstrates the utility of using historic data and specimens collected for other purposes to expand the geographic and ecosystem coverage for larger more regional-scale and even basin-wide assessments such as those needed to inform Good Environmental Status in European waters, as called for by the Marine Strategy Framework Directive.

Anthropogenic debris including microparticles (MP; <5mm) are ubiquitous in marine environments. The Salish Sea experiences seasonal fluctuations in precipitation, river discharge, sewage overflow events, and tourism-all variables previously thought to have an impact on MP transport and concentrations. Our goals are two-fold: 1) Describe long-term MP contamination data including concentration, type, and size and 2) Determine if seasonal MP concentrations are dependent on environmental or tourism variables in Elliott Bay, Salish Sea. We sampled 100 L of seawater at depth (~9 m) at the Seattle Aquarium approximately every two weeks 2019 -2020 and used an oil extraction This article is protected by copyright. All rights reserved. Accepted Articleprotocol to separate MP. We found MP concentrations ranged from 0 -0.64 particles L⁻¹ and fibers were the most common typ e observed. Microparticle concentration exhibited a breakpoint on April 10, 2020, where estimated slope and associated MP concentration significantly declined. Further, when considering both environmental as well as tourism variables, temporal MP concentration was best described by a mixedeffects model with tourism as the fixed effect and the person counting MP as the random effect. While monitoring efforts presented here set out to identify effects of seasonality and interannual differences in MP concentrations, it instead captured an effect of decreased tourism due to the global Covid-19 pandemic. Long-term monitoring is critical to establish temporal MP concentrations and to help researchers understand if there are certain events, both seasonal and sporadic (e.g. rain events, tourism, or global pandemics), when the marine environment is more at risk from anthropogenic pollution.

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