Vertical flux of chlorophyll a under fast ice near Syowa Station, Antarctica, in austral summer, 1991/1992

Abstract

Sinking particles were collected using sediment traps, which were deployed at depths of 25 or 30m under fast ice near Syowa Station, Antarctica, from January 6 to February 6, 1992. Using the samples, fluxes of chlorophyll a (Chl a) were estimated and the contribution of algal sinking to the decrease of phytoplankton biomass after the summer bloom was evaluated. The Chl a concentration, integrated above the depths at which the sediment traps were deployed, reached a maximum in mid-January. The Chl a flux became high after the maximum of the concentration was recorded. In the Chl a decreasing phase, daily decreasing rates of the Chl a concentrations in the water columns were 8.71-10.4mg Chl a m-2 day-1 . During this period the Chl a fluxes accounted for only 3.6-4.0 of the decreasing rates. These observations imply that algal sinking is not the major process of phytoplankton biomass decrease after the summer bloom.