Planktonic 18S rRNA gene sequences (V4 region) from water samples collected inside the northern coral-reef lagoon of Mo'orea (French Polynesia) and 4 km offshore, in the tropical open ocean.
In this work, surface water samples (2L) were collected at two sampling points: one located 4 km offshore in the open ocean (OO) over a depth of 1200 m; and the other located in the back-reef (BR) lagoon, over a depth of ~2.5 m. Samples for DNA collection were done every 6 h over a period of 34 h on April 12-13 (BR) and April 19-20 (OO) from the surface (0-50 cm) using a small boat. Sampling times were 04:00, 10:00, 16:00, 22:00, 04:00, 10:00, and 14:00 (13:00 at OO) local time. The microbial biomass was then collected on 0.2 µm pore-size, 47 mm diameter polycarbonate filters using a peristaltic pump. The filters were flash frozen in liquid N2 and stored at -80°C. Total DNA was extracted using the phenol-chloroform protocol as described in Massana et al. (1997). Eukaryotic diversity was determined by amplicon sequencing of the V4 regions of the 18S rDNA genes using the Illumina MiSeq platform and paired-end reads (2 x 250 bp). PCR amplifications were done using the eukaryotic universal primers V4F (5'-CCAGCASCYGCG GTAATTCC-3') and V4R (5'-ACTTTCGTTCTTGATYRR-3') (Balzano et al. 2015). All samples were sequenced at the Research and Testing Laboratories (RTL, Lubbock, TX, USA).  References:   Balzano, S., Abs, E., and Leterme, S. (2015). Protist diversity along a salinity gradient in a coastal lagoon. Aquat. Microb. Ecol. 74, 263–277.  Massana, R., Murray, A. E., Preston, C. M., and DeLong, E. 1302 F. (1997). Vertical distribution and phylogenetic characterization of marine planktonic Archaea in the Santa Barbara Channel. Appl. Environ. Microbiol. 63, 50–56.