Algal pigment patterns in different watermasses of the Atlantic sector of the Southern Ocean during fall 1987

During the autumn of 1987 a survey was carried
out in the Atlantic sector of the Southern Ocean in order
to study phytoplankton community structure in relation
to hydrological features. The positions of the boundary
zones, determined by means of hydrological and chemical
properties (especially silicic acid) match with previous
studies. The phytoplankton community structure was
studied by means of algal pigment fingerprints. A cluster
analysis of the main phytoplankton pigments revealed the
presence of four distinctive phytoplankton communities in
the area. In three cluster groups phytoflagellate pigments
of different taxonomical groups were found which showed
different relative abundance between the cluster groups. In
between the Polar Front Zone and the Weddell Scotia
Confluence a fourth group was found which was rich in
diatoms as compared to the other cluster groups. High
concentrations of the fucoxanthin related 19'-hexanoyloxyfucoxanthin
indicated the relative importance of
Prymnesiophyceae during fall in this area. The relative
contribution of each taxonomical group to total phytoplankton
biomass was estimated by using specific pigment
ratios. This calculation showed that in this time of the year
phytoflagellate biomass (especially Prymnesiophytes) surpasses
diatom biomass.