In vitro and in situ derived rates of gross production, net community production and respiration of oxygen in the oligotrophic subtropical gyre of the North Pacific Ocean

Abstract

Primary production rates were determined in the central North Pacific Gyre from in vitro and in situ changes in dissolved oxygen; the measurements were made over periods of 12 and 24 h. In situ rates were measured at three depths within the surface mixed layer and compared to in vitro changes in bottles. Clean techniques were used for the collection and incubation of samples. Rates of gross production, net community production and respiration determined from in vitro incubations compared favourably with in situ derived rates, with no evidence of major (i.e. 10-fold) systematic discrepancies between the two approaches. High chlorophyll-normalized rates of photosynthesis were measured both in vitro and in situ, which was taken as strong evidence that in vitro techniques were not seriously in error. The in situ rates of production were shown to be sufficient to produce the observed sub-surface oxygen maximum of ca 107–110% and to sustain the calculated losses of oxygen to the atmosphere from the mixed layer and particulate carbon export from the euphotic zone.