Methods and sampling are reported in Tucker et al., (2021)

Sample collection and environmental parameters

Between August 2017 and June 2019, seawater was collected from a depth of 2 m at 10 sites in and around Kāneʻohe Bay, Oʻahu, Hawaiʻi, on a near-monthly basis (20 sampling events over 23 months). At each station, seawater samples for biogeochemical analyses and nucleic acids were collected, and in situ measurements of seawater temperature, pH, and salinity were made with a YSI 6,600 sonde (YSI Incorporated, Yellow Springs, OH, USA). Approximately one L of seawater was prefiltered using an 85 μm Nitex mesh and subsequently collected on a 25-mm diameter 0.1-μm pore-sized polyethersulfone (PES) membrane for nucleic acids (Supor-100, Pall Gelman Inc., Ann Arbor, MI, USA). The filters were submerged in DNA lysis buffer (Suzuki et al., 2001; Yeo et al., 2013) and stored at −80 °C until extraction.

Subsamples for chlorophyll a were collected by filtering 125 mL of seawater onto 25-mm diameter GF/F glass microfiber filters (Whatman, GE Healthcare Life Sciences, Chicago, IL, USA), and stored in aluminum foil at −80 °C until extraction in 100% acetone and subsequent measurement of fluorescence with a Turner 10AU fluorometer (Turner Designs, Sunnyvale, CA, USA) followed standard techniques (Welschmeyer, 1994). Seawater for cellular enumeration was preserved in two-mL aliquots in a final concentration of 0.95% (v:v) paraformaldehyde (Electron Microscopy Services, Hatfield, PA, USA) at −80 °C until analyzed via flow cytometry. Cellular enumeration of cyanobacterial picophytoplankton (marine Synechococcus and Prochlorococcus), eukaryotic picophytoplankton, and non-cyanobacterial (presumably heterotrophic) bacteria and archaea (hereafter referred to as heterotrophic bacteria) was performed on an EPICS ALTRA flow cytometer (Beckman Coulter Inc., Brea, CA, USA), following the method of Monger and Landry (Monger & Landry, 1993).