Graduation Year

2026

Document Type

Thesis

Degree

M.S.

Degree Name

Master of Science (M.S.)

Degree Granting Department

Integrative Biology

Major Professor

Heather Judkins, Ph.D.

Committee Member

Melanie Riedinger-Whitmore, Ph.D.

Committee Member

Patrick Schwing, Ph.D.

Keywords

Bioaccumulation, Cephalopod, Marine-debris, Polyethelene, Spatial distribution

Abstract

Microplastic contamination is a pervasive global issue, yet its impact on ecologically significant cephalopod populations remains poorly understood. This study quantified microplastic prevalence and distribution in longfin squid (Doryteuthis pealeii), a key trophic link in the Gulf of Mexico. Following hydrogen peroxide digestion of digestive tract and mantle tissues, microplastics were isolated via vacuum filtration and characterized using microscopy. Fourier-transform infrared (FTIR) spectroscopy confirmed polymer identities. Microplastic contamination was exceptionally high, with 96.4% of individuals containing particles (mean = 36.6 ± 20.0 particles per individual, range = 0–94, n = 110 squid). From 4,072 total particles analyzed, fragments dominated (98.3%), while fibers comprised only 1.7%. FTIR analysis confirmed polyethylene terephthalate (PET, 60.5%) and low-density polyethylene (LDPE/PE, 39.5%) as the primary polymer types. Contamination levels did not differ significantly by squid sex or size class but showed significant spatial variation across sampling sites (p < 0.001), suggesting localized pollution sources. These findings establish the first baseline for microplastic contamination in Gulf of Mexico longfin squid and demonstrate that this commercially and ecologically important species experiences widespread exposure to marine plastic debris, with implications for trophic transfer and ecosystem health.

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