Production rates of C37 alkenones determined by 13C-labeling technique in the euphotic zone of Sagami Bay, Japan

The production rates of C37 alkenones in the euphotic zone of Sagami Bay, Japan were determined by the 13C-labeling technique in conjunction with gas chromatography–mass spectrometry. The maximum in the alkenone production rate (C37:2 plus C37:3 alkenones) was observed at 5 m depth and the specific production rate, calculated from the rate of production relative to standing stock in suspended particles, was 0.64 day−1 at this depth. Temperature, based on the newly-produced alkenone unsaturation index (Uk′37), was close to in situ temperatures at the depth where alkenones production was active.