THE RELATIONSHIP BETWEEN COMMUNITY RESPIRATION AND ETS ACTIVITY IN THE OCEAN

We have studied the relationship between community respiration (R) and enzymatic activity of the electron transport system (ETS) in upper oc ean microbial communities (<225 mu m) from different oceanic regions. In all except one of the regions, R and ETS were significantly positiv e correlated. This supports the hypothesis that ETS can be widely used to estimate plankton respiration in natural marine communities (Packa rd, T.T., Adv. Aquat. Micri,biol, 3, 207-261, 1985). A regression equa tion was obtained between all the R and ETS data studied, lo derive re spiration from ETS activity. This equation yields a mean error in the prediction of +/- 34%, similar to the errors obtained applying the equ ations at each area, but lower than the error obtained when using the mean R:ETS ratio to determine respiration (+/- 45%). Our results sugge st that the use of the ETS-R algorithm, along with measurements of ETS activity in seawater, facilitates the estimation of seawater respirat ory oxygen consumption on the mesoscale. This means that by using this approach one could extend our knowledge of oceanic respiration over l arge temporal and spatial scales, and begin to use respiration, not on ly productivity, in addressing carbon balance problems in the upper oc ean.