A method for the continuous measurement of in vivo chlorophyll concentration

Abstract In vivo chlorophyll, like many other organic molecules, possesses the ability to fluoresce. This fluorescence was measured continuously with a modified model III Turner fluorometer at sea. Reliable readings were obtained over the range of 0·04–2·0 mg chlorophyll a m −3 while on a 21-day cruise off the coast of Baja California. Since the relationship between fluorescence and chlorophyll was linear on all scales, it should be possible to continuously monitor chlorophyll from 0·04 to between 10 and 15 mg m −3 , a range adequate for all open ocean studies.