As part of the DEEPEND Consortium, our laboratory has been characterizing the microbial community composition and structure in the northern Gulf of Mexico (NGoM) pelagic waters using modern molecular ecology methods. We had previously sequenced a large cache of 16S rRNA gene data, which included 466 samples from two cruises in 2016 (May: DP03, August: DP04). To enhance taxonomic identifications, Mr. Tourani's MS thesis in Jose Lopez's laboratory at Nova Southeastern University has taken the same baseline 16S data and transformed it to infer the potential functions of the midwater microbiomes across time and space. The Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt) approach was used for predicting biomolecular function based on the KEGG metabolic database. Strong depth stratification of metabolic function was observed (p<0.001), with a major shift in function between euphotic zone and aphotic zone, associated with a major differential abundance of photosynthetic functional signatures. Temporal analyses showed photosynthetic primary productivity was significantly different across season but not year, which may be attributed to high seasonal outflow of the Mississippi river.