The estimation of the abundance of ultraplankton

Abstract

Methods of assessing the amount of ultraplankton in the surface waters of the sea are discussed with particular reference to their use on board ship. A fluorometric technique for the determination of the amount of chlorophyll a produced by the ultraplankton is described, together with a method for estimating the relative amounts of net-plankton and ultraplankton. It is shown that in the Barents Sea, and some other northern waters, the ultraplankton may at times contribute over 90% of the total chlorophyll a in the water.