Dataset: Gross oxygen production
Deployment: KM1910

Seawater samples for the incubations were collected in triplicate before dawn at six different depths (5, 25, 45, 75, 100, and 125m) with 12-L Niskin® bottles attached to a CTD rosette. Subsamples were taken from the Niskin bottles in acid-washed volume- calibrated 150-mLquartz glass bottles with ground-glass stoppers. The bottles were first rinsed with the seawater sample, and then filled from bottom to top using acid- washed silicon tubing, allowing the water to overflow at least twice the volume of the bottles. Before closing, the incubation bottles were spiked with 650 µL of ¹⁸O-H₂O (97.2% ¹⁸O, Medical Isotopes) for the surface samples (5-45 m) and 1,000 µL for deeper samples (75-125 m). The samples were deployed in situ at the corresponding depths before dawn using a free-drifting array, and incubated until dawn. After recovery, the incubated samples were poisoned with saturated mercuric chloride solution to inhibit biological activity. Time-zero samples were also collected pre-dawn and poisoned at the time of the deployment.