(AFRICAN SUN MeDIA, 2008) Smith, Valdon R.; Froneman, P. William
Nutrient concentrations in the open waters of the Polar Frontal Zone (PFZ)
are highly variable, reflecting the region’s complex oceanographic regime.
Surface concentrations of nitrate, silicate and phosphate range from 9.5 to
97.5, from 0.2 to 16.5 and from < 0.1 to 16.6 mmol m-3, respectively (Allanson
et al. 1985; Duncombe Rae 1989; Ismail 1990; Balarin 2000). Changes in
nutrient concentrations coincide with the intrusion of Antarctic surface water
from the south and sub-Antarctic surface water from the north (Ansorge et
al. 1999; Froneman et al. 1999). Mesoscale features such as far field eddies or
the eddies generated by the interaction between the Antarctic Circumpolar
Current (ACC) and the South-West Indian Ridge further contribute to the
heterogeneity in nutrient concentrations within the surface waters of the PFZ
(Ansorge & Lutjeharms 2002, 2003; Ansorge et al. 2004).