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We present nearly 3 years of mixed layer O2/Ar measurements at Station ALOHA, the site of the Hawaii Ocean Time-series program. At approximately monthly intervals between November 2013 and August 2016, duplicate samples were collected in the mixed layer every 3 hours covering a diel cycle. Mean O2/Ar saturation values indicated that the mixed layer was consistently net autotrophic during the study period. Despite the low metabolic rates that characterize this oligothrophic oceanic region, O2/Ar saturation values typically varied throughout the day as a result of biological processes, showing minimum values near sunrise and maximum values near sunset. We used this diel pattern in O2/Ar saturation values to determine in situ<\em> rates of gross oxygen production and respiration at Station ALOHA. In addition, we applied two different approaches to determine net community production in the mixed layer, one that averages over short time scales (24 hours) and the more conventional one, that integrates over the residence time of dissolved O2 in the mixed layer (~1-3 weeks). Based on the latter, we estimate the mixed layer annual net community production for 2014 and 2015 to be 2.3 and 2.5 mol O2 m-2 yr-1, respectively.



Ferrón, S., University of Hawaii, USA,

Barone, B., University of Hawaii, USA,

Church, M. J., University of Montana, USA,

Karl, D. M., University of Hawaii, USA,


Oral presentation

Session #:040
Date: 03/01/2017
Time: 10:45
Location: 314

Presentation is given by student: No