Geographic variation of oceanic 14C dark uptake

Abstract

In a series of midocean stations extending from high northern to high southern latitudes in both the Pacific and Atlantic Oceans we found that 14C dark uptake followed a definite geographic pattern. In temperate and equatorial regions the dark uptake was normally ≾ 10% of that in the light, but in the subtropical gyres and at high southern latitudes the average dark uptake varied from 10 to >50% of the light uptake. There was a significant and complex relationship between dark uptake, production, and standing stock that seemed to depend on the structure of the plankton community, but a relatively simple pattern could also be discerned. At production levels of > l µg C liter−1 h−1 or at standing stock levels of >40 µg C liter−1, the average dark uptake was low. At lower levels the average dark uptake was high.