HCNSO Student Theses and Dissertations

Defense Date


Document Type


Degree Name

M.S. Marine Biology

First Advisor

Jose V. Lopez, PhD

Second Advisor

Cole G. Easson, PhD

Third Advisor

Matthew W. Johnston, PhD


Microbial communities, or microbiomes, are the major drivers of global biogeochemical cycles, acting as primary producers and decomposers across the water column in the oceans. Thus, they reflect changes in physicochemical properties and nutrient composition of the ocean. However, this correlation between ecological changes and the function of marine microbiomes is poorly understood. Large-scale oceanic events such as the bottom-water oxygen-depleted zone (i.e., “dead zone”) and the Deepwater Horizon oil spill in the Gulf of Mexico (GoM) render the ecosystem fragile. These events decrease survival rates of pelagic and coastal macrofauna and affect the biodiversity of the region. As part of the DEEPEND Consortium, previously sequenced 16S rRNA gene data of 466 samples from two cruises in 2016 (May: DP03, August: DP04) were used to characterize the taxa and function of microbiomes across the Northern GoM (NGoM). The Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt) approach was used for predicting biomolecular function based on the KEGG database inferred from 16S rRNA sequences. Metabolism was the most abundant function at KEGG Level 1 (DP03: 53.1%, DP04: 52.4%), and further analyses were centered on pathways within this function. Strong depth stratification of metabolic function was observed (p

Creative Commons License

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