DOWNWARD FLUXES OF FATTY-ACIDS AND HYDROCARBONS DURING A PHYTOPLANKTON BLOOM IN THE AUSTRAL SUMMER IN BREID BAY, ANTARCTICA

Vertical fluxes of fatty acids and hydrocarbons were measured in sinki ng particles collected by a time-series sediment trap in Breid Bay, An tarctica during the austral summer December 1985 to February 1986. Tem poral variations in fatty acid fluxes were related to changes in growt h of the overlying diatom population. High contents of 21:6 alkenes an d 14:0, 16:0, 16:1, 20:5 acids of the sinking particles supported the idea that the source of the sinking organic matter was mainly diatoms. 21:6 Alkenes and 20:5 acids increased in the late exponential phase o f the overlying diatom bloom. Branched C-25 alkenes were detected in t he sinking particles. Measurements of changes in the fatty acid compos ition of the sinking particles were shown to provide useful informatio n on the ecophysiological status of the phytoplankton population as th e bloom progressed. Unsaturated fatty acid/saturated fatty acid ratios in the sinking particles indicated active growth of diatoms during th e observations. High fluxes of 20:5 acids suggested a late exponential phase and a stationary phase of the overlying diatom bloom. Copyright (C) 1996 Elsevier Science Ltd