Dataset: Results of 18S sequencing of full-length 18S rDNA for metabarcoding samples collected during R/V Point Sur cruise PS18-09 in the Western Gulf of Mexico in September 2017

On September 23, 2017, on HRR cruise Leg 1 (R/V Point Sur PS18-09), samples were collected at 6 stations (S06, S11, S16, S21, SS, and GI) from the surface depth bottle in a CTD rosette. Triplicate 500-1000 milliliter (mL) samples were filtered and immediately fixed in RNALater. Triplicate samples from each station/depth were extracted with AllPrep DNA/RNA MiniKit (Qiagen, USA) following the manufacturer's instructions. DNA concentration and quality were evaluated using a Nanodrop spectrophotometer (Thermo Fisher Scientific Inc, USA). All the samples extracted for DNA were normalized to 5 nanograms per microliter (ng/µL) concentration for the amplicon library construction.

The full-length 18S rDNA region was amplified using 18S primers (Medlin et al. 1988; Edgar & Theriot 2004). Library construction and amplicon sequencing were performed at the Campbell Lab, Texas A&M University using Oxford Nanopore minION. The output sequencing results as fasta files were deposited in NCBI's GenBank under the project number PRJNA592369.