First Advisor

Catherine de Rivera

Term of Graduation

Fall 2021

Date of Publication


Document Type


Degree Name

Doctor of Philosophy (Ph.D.) in Earth, Environment, & Society


Earth, Environment, & Society




Crabs -- Effect of water pollution on -- Oregon -- Pacific Coast, Microplastics -- Environmental aspects -- Oregon -- Pacific Coast, Plastic marine debris -- Environmental aspects -- Oregon -- Pacific Coast, Crabs -- Behavior, Crabs -- Mortality, Crabs -- Reproduction, Polypropylene fibers



Physical Description

1 online resource (vi, 141 pages)


Microplastics have been documented across the global oceans as an ubiquitous pollutant. Found in the water column, sediment, shorelines, estuaries, freshwater streams and rivers along with terrestrial soils, flora and fauna. The continuous input of plastic waste into the marine environment doesn't seem to be slowing as the amount of plastic created each year increases globally.

This study investigated (1) the effects of microplastic ingestion in the indicator species, the Pacific mole crab (Emerita analoga), testing the predator avoidance behavior, reproductive output and parasitism effects when an adult female gravid crab had ingested microplastics (2) adult mortality, hatching success and growth time of indicator species, the Pacific mole crab (Emerita analoga), when exposed to an environmentally relevant amount of polypropylene microplastic fibers and lastly (3) the presence of microplastic ingestion in the important commercial fishery organism the Dungeness crab (Metacarcinus magister).

Conclusions show that there are deleterious effects of microplastic ingestion on Pacific mole crabs across testing parameters, including increased mortality, slower predator avoidance behaviors and significant effects on reproductive output and success. Within Dungeness crabs, we found that these crabs ingested microplastics across locations as well as different body parts investigated. However, Dungeness crabs were found to have the lowest amount of microplastics per gram of body tissue compared to other fishery organisms researched in the Pacific Northwest such as clams and oysters.


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