Document Type



Doctor of Philosophy (PhD)



First Advisor's Name

Heather D. Bracken-Grissom

First Advisor's Committee Title

Committee chair

Second Advisor's Name

Ligia Collado-Vides

Second Advisor's Committee Title

Committee member

Third Advisor's Name

DeEtta Mills

Third Advisor's Committee Title

Committee member

Fourth Advisor's Name

Jose Maria Eirin-Lopez

Fourth Advisor's Committee Title

Committee member

Fifth Advisor's Name

Elizabeth Anderson

Fifth Advisor's Committee Title

Committee member


DNA-barcoding, Crustacea, Gulf of Mexico, Taxonomy

Date of Defense



In this dissertation I investigate the biodiversity of marine deep-water crustaceans of the Gulf of Mexico and adjacent waters, focusing on pelagic crustaceans. Taxonomic and molecular techniques were utilized to document adult and larval crustacean specimens to better under their taxonomy, life history, evolutionary relationships and cryptic biodiversity. The use of molecular techniques to study organisms from habitats with limited accessibility provides tremendous potential. With prevalent anthropogenic threats and the delicate nature of deep-water habitats, the need to improve our understanding of these systems is clear. Molecular techniques can act as a fundamental tool to complement traditional taxonomy. The application of DNA sequence data, alongside morphological investigations, represents a promising and effective approach to identifying specimens at all stages of life. In all chapters, samples were collected across eight deep-sea research cruises (up to 2000m) in the Gulf of Mexico and the Florida Straits. In Chapter II, I use DNA barcoding methods alongside taxonomic methods to study the evolutionary relationships, cryptic diversity, and distributional records across 82 species within Caridea, Dendrobranchiata, Euphausiacea, Amphipoda and Lophogastrida. Several new distributional records for the Gulf of Mexico were included including one family, two genera and six species. In Chapter III, I used the data collected as part of Chapter II to identify unknown developmental stages of decapods collected from the Gulf of Mexico and adjacent waters. DNA barcoding from the 16S and COI regions allowed for the identification of 14 unknown larval species (16 developmental stages) from Caridea and Dendrobranchiata. Alongside these genetic methods, I provide taxonomic descriptions and illustrations to aid in future studies. In completion, this dissertation advances the field of crustacean biodiversity by providing a robust inventory of pelagic crustaceans from the Gulf of Mexico. This information has resulted in a better understanding of basic biology, life history, evolutionary relationships and larvae-adult linkages for the deep-water crustacean species.





Previously Published In

Varela, C., Golightly, C., Timm, L.E., Wilkins, B., Frank, T., Fenolio, D., Collins, S.B. and Bracken-Grissom H.D. (2021). DNA barcoding enhances large-scale biodiversity initiatives for deep-pelagic crustaceans within the Gulf of Mexico and adjacent waters. Journal of Crustacean Biology, 40(1): 1-18.

Varela, C. and H. Bracken-Grissom (2021). A mysterious world revealed: Larval-adult matching of deep-sea shrimps from the Gulf of Mexico. Diversity, 13 (10): 457.



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