Date of Award

Fall 12-2020

Degree Type

Masters Thesis

Degree Name

Master of Science (MS)


Ocean Science and Engineering

Committee Chair

Dr. Frank Hernandez

Committee Chair School

Ocean Science and Engineering

Committee Member 2

Dr. Kevin Dillon

Committee Member 2 School

Ocean Science and Engineering

Committee Member 3

Dr. Leila Hamdan

Committee Member 3 School

Ocean Science and Engineering

Committee Member 4

Dr. Robert Griffitt

Committee Member 4 School

Ocean Science and Engineering


Microplastics are a concern in marine environments because they are highly durable, ubiquitous, and can be mistaken for food and ingested by small organisms. Pelagic Sargassum, an important habitat for larval and juvenile stages of many fish species, is found in large surface aggregations, and may provide complex structure in which microplastics become trapped. This could lead to greater risk of microplastic ingestion by fish early life stages associated with Sargassum habitats. To better understand the impacts of microplastics within Sargassum communities, this study examined 1) microplastic concentrations and ingestion by juvenile fishes associated with Sargassum; 2) the microbial communities associated with the Sargassum and microplastics; and 3) the influence of microplastic ingestion on the microbiomes of juvenile Gray Triggerfish. Neuston net samples were collected in 2017 and 2018 from open water and Sargassum habitats in the Gulf of Mexico to collect microplastics and fishes. Microplastic abundance was significantly higher in Sargassum habitats relative to open water habitats. Microplastics were identified in the stomach contents of many species of juvenile fishes with total microplastic frequency of occurrence ranging between 14.7-24.7%. Microplastics had a unique microbiome when compared to the surrounding environment. The microplastic microbiome was found to influence Gray Triggerfish gut microbiomes. The results from this project demonstrate that microplastics are being ingested by juvenile fishes in Sargassum and the unique microbiome of microplastics are influencing fish gut microbiomes.