Quantifying subtropical North Pacific gyre mixed layer primary productivity from Seaglider observations of diel oxygen cycles

Using autonomous underwater gliders, we quantified diurnal periodicity in dissolved oxygen, chlorophyll, and temperature in the subtropical North Pacific near the Hawaii Ocean Time-series (HOT) Station ALOHA during summer 2012. Oxygen optodes provided sufficient stability and precision to quantify diel cycles of average amplitude of 0.6μmolkg . A theoretical diel curve was fit to daily observations to infer an average mixed layer gross primary productivity (GPP) of 1.8mmol O2m 3 d . Cumulative net community production (NCP) over 110days was 500mmol O2m 2 for themixed layer, which averaged 57m in depth. Both GPPandNCP estimates indicated a significant period of below-average productivity at Station ALOHA in 2012, an observation confirmed by C productivity incubations and O2/Ar ratios. Given our success in an oligotrophic gyre where biological signals are small, our diel GPP approach holds promise for remote characterization of productivity across the spectrum of marine environments.