Jt. Lehman et Dk. Branstrator, NUTRIENT DYNAMICS AND TURNOVER RATES OF PHOSPHATE AND SULFATE IN LAKEVICTORIA, EAST-AFRICA, Limnology and oceanography, 39(2), 1994, pp. 227-233
The dominant process removing sulfate from the water of Lake Victoria
is biological uptake by plankton > 1 mum in size. Uptake of sulfate in
the water column is substantially greater than uptake at the sediment
surface. Despite low ambient concentrations (3-4 muM), rates of uptak
e of sulfate by phytoplankton do not increase when additional sulfate
is added to the water, and ambient concentrations are adequate to supp
ort maximum uptake rates. Uptake rates for phosphate are similarly nea
r-maximal in offshore waters. Furthermore, experimental addition of su
lfate or phosphate fails to increase biomass production over control l
evels, but addition of N alone or in combination with P and S does inc
rease algal biomass. Although sulfate concentrations in Lake Victoria
are lower than values reported for any large lake worldwide, our resul
ts indicate that sulfate behaves as a nonlimiting nutrient in Lake Vic
toria and that it does not limit the primary productivity of the lake.