The physico-chemical properties and plankton diversity were studied in Osere
stream, Ilorin, Kwara State, Nigeria from November 2009 to April 2010. Surface water and
plankton samples were collected from three sampling stations. High value of Biochemical
Oxygen Demand of 8.68mg/L and low value of Dissolved Oxygen of 1.23mg/L at the point of
entry than at the upper flow of the stream indicate pollution stress. Also the presence of high
abundance of
Anabaena
and
Oscillatoria
sp. which are pollution indicator species shows the
negative effect the effluent from the detergent factory has on the stream, thus posing a
potential threat to the people who live around and depend on the stream for daily use, hence
the need for proper management of the stream.
