Term of Award

Fall 2021

Degree Name

Master of Science in Biology (M.S.)

Document Type and Release Option

Thesis (open access)

Copyright Statement / License for Reuse

Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 License.


Department of Biology

Committee Chair

Christine Bedore

Committee Member 1

Johanne Lewis

Committee Member 2

Katherine Lyons

Non-Voting Committee Member

Lisa Hoopes


Assessing macronutrient transfer is important for estimating ecosystem health and structure. This nutrient transfer is facilitated through trophic position interactions and the consumption of biomass. Lipids are macronutrients that can be used to assess energy flow. Triglyceride (TAG) and free fatty acids (FFA) are important lipids that are obtained from diet and integrate into tissues. They are representative of energy stores and potential energy available for metabolic processes. In marine ecosystems, stingrays occupy the mesopredator niche, facilitating nutrient transfer from lower to higher trophic positions. Stingrays consume a variety of prey items ranging in lipid content, but how lipid metabolites compare between batoid tissues and across species is poorly understood. This study aims to determine tissue-specific and species-specific differences in TAG and FFA in liver, plasma, and muscle tissues of four stingray species. Liver, muscle, and plasma samples were collected from butterfly rays (Gymnura lessae), Atlantic stingrays (Hypanus sabinus), bluntnose stingrays (Hypanus say), and southern bullnose rays (Myliobatis freminvillii) from the Northwest Atlantic. Tissue concentrations of TAG and FFA were quantified using colorimetric assays and analyzed using a linear mixed-effects model. Overall, liver had higher TAG and FFA concentrations than plasma and muscle. However, bullnose ray and Atlantic stingray muscle TAG and FFA were not significantly different from liver. Butterfly rays had significantly greater liver TAG than Atlantic and bluntnose stingrays. Bullnose rays had significantly greater muscle TAG and FFA than all three species. The butterfly rays’ liver TAG content may be attributed to their diet since they primarily consume teleosts. Bullnose rays’ muscle TAG and FFA are unusual and whether muscle has the capacity for lipid oxidation or is an alternative lipid storage tissue should be further researched. Results from this study can be used as to further understand energy flow through trophic positions.

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Research Data and Supplementary Material