Graduation Year

2025

Document Type

Thesis

Degree

M.S.

Degree Name

Master of Science (M.S.)

Degree Granting Department

Biology (Integrative Biology)

Major Professor

Heather Judkins, Ph.D.

Committee Member

Alison Gainsbury, Ph.D.

Committee Member

J. Sean Doody, Ph.D.

Committee Member

Tracey Sutton, Ph.D.

Keywords

Bathypelagic, Diet, Fish, Food web, Mesopelagic, Prey

Abstract

Little is known about the feeding dynamics of deep-sea communities, despite their significant ecological importance. Deep-pelagic communities contribute to marine biodiversity and ecosystem stability while directly offsetting climate change via carbon sequestration. Omosudis lowii is an understudied, deep-sea fish found in temperate and tropical waters worldwide, including the Gulf of Mexico. Omosudis lowii have large jaws and distensible stomachs, allowing them to capture prey items larger than their body size. The present seminal study used stomach content analysis to quantitatively describe the O. lowii trophic ecology, providing baseline data regarding diet composition, feeding selectivity, and factors that impact prey selection. Dissections were conducted on 574 preserved specimens collected by the Deep Pelagic Nekton Dynamics of the Gulf of Mexico Consortium (DEEPEND) on research cruises spanning 2011 to 2023. Findings suggest that this species is one of the few deep-pelagic fishes that preys primarily on cephalopods and is the first to propose an ontogenic shift in diet from cephalopods to fishes with age. Results are compared with environmental, spatial, and temporal data to provide a better understanding of the distribution and feeding ecology of O. lowii throughout its life cycle in this region. This project also reveals previously unknown findings regarding O. lowii endoparasites and morphometrics.

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