Defense Date


Document Type


Degree Type

Master of Science

Degree Name

Marine Science

First Advisor

David Kerstetter, Ph.D.

Second Advisor

Abigail Renegar, Ph.D.


microplastic, pollution, seabird, brown pelican, laughing gull


Plastic pollution is a global problem that exists in even the most remote locations. Plastic biodegrades slowly but breaks apart into progressively smaller pieces relatively quickly. Plastic pieces‘microplastics’ and are of interest due to their ability to associate with harmful chemicals known as persistent organic pollutants (POPs). Through microplastics, POPs can enter the food web and have the potential to biomagnify in higher trophic levels. Once ingested, microplastics and their associated POPs can reduce body condition, alter reproduction rates, and increase mortality. Marine birds are at a higher risk of ingesting microplastics because they feed at the ocean’s surface where buoyant microplastics commonly accumulate. However, very little is known about the prevalence of microplastics and coastal seabirds. This study quantifies the amount of microplastics found in four species of seabirds based on quantity, size, type (fiber or fragment), and color (light, mid, or dark). Bird specimens were obtained from local wildlife rescue centers, and a total of 643 microplastic particles were identified, with 43 of the 44 study specimens found to contain microplastics (97.7% frequency). The ‘fiber’ type and the ‘mid’ color tone were the most common microplastics. There were no significant differences between species for particle sizes, but Brown Pelicans contained significantly more particles than the other three species. These results highlight the prevalence of plastic pollution in these mesopredators, but more work is needed to further determine microplastic patterns between taxa and foraging environments.