Abstract:
The aquatic environment is particularly vulnerable to the effects of contaminants as effluents
from municipal and industrial wastewater continually add numerous harmful exogenous
compounds. Lake Manyame is a peri urban freshwater reservoi r that is subject to municipal
and industrial discharge as well as agricultural run off. Adult Nile tilapia ( Oreochromis
niloticus were sampled from L. Manyame during low flow and high flow seasons from
selected locations. The samples were processed in th e field for histology and biochemical
analysis of selected biomarkers of oxidative stress. Induction of reduced glutathione (GSH),
carboxylesterase (CES) and malondialdehyde (MDA) was evident at all the sites. There were
no significant variations between s it es except in the last low flow season and there was an
upward trend between the first season and the subsequent sampling periods. Gonadal
histology did not show occurrence of any intersex as a sign of endocrine disruption. The
prevalence of histological le sions in the gonads was highest in the last sampling seasons,
suggesting a progressive deterioration of water quality over time.
