Genomic DNA from seagrass epiphytes and sediments was PCR-amplified targeting the V4V5 region of the 16S rRNA gene using primers 515F/926R (Parada et al., 2016) with Illumina adapter linkers. A two-step PCR approach (Naqib et al., 2018) was used with repliQa HiFi ToughMix (Quantabio), followed by AMPure XP bead cleanup. Amplicons were pooled and sequenced as paired-end reads (2259 bp) on an Illumina NovaSeq 6000 at the Roy J. Carver Biotechnology Center, University of Illinois, after initial library QC on a MiniSeq (Illumina).