In vitro O2 fluxes compared with 14C production and other rate terms during the JGOFS Equatorial Pacific experiment

We report rates of gross and net O-2 production measured in vitro during JGOFS cruises in the equatorial Pacific in spring and fall, 1992. We scale O-2 productivities to net and gross C production. We then compare the calculated rates with C-14 production and with new/export production measured by various techniques. C-14 productivities in samples incubated for 24 h are about 45% of gross carbon production rates calculated from gross O-2 production. The difference is compatible with expected rates of the Mehler reaction, photorespiration, excretion, and community mitochondrial respiration. C-14 production rates are similar to net carbon production rates in the upper half of the euphotic zone. At lower irradiances, where net C production can be zero or less, C-14 productivities lie between net community production and gross primary production. Net carbon production rates in vitro are a factor of similar to 4-20 times greater than estimates from drifting sediment trap and tracer transport studies. This difference probably reflects anomalous accumulation of POC in bottles because of the exclusion of grazers. (C) 1999 Elsevier Science Ltd. All rights reserved.