Temporal variability of microparticles under the Seattle Aquarium, WA: Documenting the global Covid‐19 pandemic

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 protocol to separate MP. We found MP concentrations ranged from 0 – 0.64 particles L⁻¹ and fibers were the most common type observed. Microparticle concentration exhibited a breakpoint on April 10, 2020, where estimated slope and associated MP concentration significantly declined. Further, when considering both environm...