Faculty Advisor

Hodum, Peter

Area of Study

Science and Mathematics

Publication Date

Summer 2018


Global plastic production rates are currently at the highest that they have ever been and are projected to continue to increase over the next 20 years. Models that have only accounted for surface plastics have severely underestimated actual plastic loads in the world’s oceans, largely due to the distribution of microplastics below the water’s surface. Despite being ingested by organisms at nearly every trophic level and observed in virtually every ocean environment, the complex nature of microplastics’ distribution patterns remains poorly understood. Recent studies have observed distinct depth profiles of microplastics, thereby implying differential bioavailability to biotic communities depending on their position in the water column. To date, depth profiles of microplastics have only been characterized in open ocean environments and gyres, and no study of depth profiles has directly, quantitatively linked vertical distribution of microplastics in the water column to ingestion by marine organisms. This study has aimed to further our understanding of microplastic depth profiles and the implications for biological communities by (1) determining the vertical distribution of microplastics in a stratified marine habitat in Puget Sound and (2) relating that distribution to ingested plastic loads in a biological indicator species at different depths. In both water samples and mussel samples taken from our study site in Totten Inlet, 99% of plastics found were filamentous. No distinct patterns of distribution were observed in either water samples or mussel samples from 0-4 m depths.


University of Puget Sound