Evidence for a Photo synthetic Daily Periodicity1

Abstract

It appears that there is a variation of around 5.7‐fold in the ability of oceanic phytoplankton to photosynthetically fix carbon depending upon the time of day the productivity of fixed carbon is determined. The maximum photosynthetic ability appears to be during the few hours before mid‐day, and the minimum ability around 1900 hours as determined by the carbon 14 “light‐dark bottle” technique. The original determinations were made in surface waters at surface temperature on three crossings of the equatorial region between about 110 and 140 degrees West Longitude.