Ocean Science

The Means of Production

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Science  24 Jun 2005:
Vol. 308, Issue 5730, pp. 1843
DOI: 10.1126/science.308.5730.1843b

The equating of new production (marine primary production fueled by nutrients supplied externally, rather than by nutrients derived from recycled organisms) to export production (primary production lost to recycling through removal to deep waters and sediments) is a common assumption in many studies of marine chemistry. This assumption has allowed numerous estimates of the hard-to-measure quantity of export production to be made, using the more easily measured new production. These quantities are then used to calculate how much CO2 marine organisms might remove from the atmosphere, a central question in climate studies.

Plattner et al. investigate the strength of this assumption for annually integrated new and export production in the central Californian marine upwelling system, using an eddy-resolving, coupled physical-ecosystem-biogeochemical model. They find that new and export production can decouple on a local scale (hundreds of kilometers), because of horizontal transport by persistent meso- and submesoscale circulation patterns, as well as by offshore flow caused by Ekman transport. Thus, although these results do not pertain to global estimates over long periods of time, they do illustrate that the concept of the equality of new and export production has to be used with care, particularly over short spatial and temporal scales. — HJS

Geophys. Res. Lett. 32, 10.1029/2005GL022660 (2005).

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