The Western Society of Naturalists 101st Annual Meeting was held virtually from November 5-8, 2020.

Schedule Overview

Page 214-215

SEA SURFACE MICROPLASTICS: AN INSHORE-OFFSHORE GRADIENT OFF THE OLYMPIC PENINSULA Wood, R.S.*; Granek, E.F. Portland State University

The lack of data on plastic debris in various environmental compartments creates a vast data gap for many reasons. These include no codified methodology to characterize microplastics by morphology and polymer type, as well as gaps regarding contamination control & validation techniques. In September 2019, sea surface samples were collected off the Olympic Peninsula, WA to address three research questions. First, is variability in microplastic abundance driven by transect location and/or distance from shore Second, how does microplastic morphology and polymer composition vary relative to transect location and distance from shore? Third, which environmental variables contribute to patterns of microplastic variability in abundance and type? The project provides a distribution-abundance baseline for sea surface microplastics (2-3mdeep) along two transects: La Push & Grays Harbor, WA, USA. Organic matter was digested using a KOH solution. After measuring, photographing, and counting MPs via a dissection microscope, lipophilic Nile Red dye (10µg/mL) was applied, MPs were fluoresced at 455nm & counted again. Metrics to count & characterize the MPs found were: size (>63um), color, morphology (fragment, film, fiber, fiber bundle, foam, microbead, other), and polymer type via micro-FTIR. Microplastics count/type, independent environmental conditions, and location data will be analyzed using a t-test. Multiple regression will be used to identify relationships to environmental variables and an NMDS ordination to compare dissimilarity within the multivariate characterization data.