Abstract:

Eutrophication of Lake Victoria is attributable to the burgeoning human
population in its watershed. The lake is expenencing increasing anthropogenic P hds
from expanding urban, agricultural and industrial development. Paieolimnological and
nutrient status indicators indicate excess P on a system scale. Excessive P has stimulated
phytoplankton biomass and promoted blooms of N-fixing cyanobacteria. High alpl
biomass provides organic matter that contributes to extensive oxygen depletion in
hypolimnetic waters during the stratified penod. Low oxygen concentrations cause a
complex suite of direct and indirect impacts including loss of aquatic animals and
changes in nutrient cycling. Anoxia may be contributing to fish kills upon upwelling in
Lake Victoria, and dso causes release of materials bound to the bottom sediments
including P. This release of nutrients reinforces eutrophication during periods of deeper
and stronger mixing when dissolved nutrients are redistributed in the water column.