Effects of heavy metal pollutants on the reproduction of Nile tilapia
Many farms surrounding Lake Manzala near the Suez Canal area suffer from severe environmental pollution. The source of pollution in that area comes from different sources of industrial, sewage, agricultural activities and petroleum companies which present in that area. This research aims to study the effects of some environmental pollution especially heavy metals at these locations of Lake Manzala on the Oreochromis niloticus reproduction. There were two groups, one was an intoxicated group (50 fish) and the other one was 50 fish from Abbasa farm as a control group. Fish were transported to the laboratory for studying clinical signs, histopathological examination and detection of heavy metals accumulation in fish organs which involved in reproduction as (liver, brain, ovary, testes) The results showed that there was a significant difference between the intoxicated group and the control group. The metals levels were Fe >Cu>Pb>Cd respectively. The accumulation of (Fe and Cu) were in liver>brain>ovary>testis respectively. While Pd was accumulated in liver >brain> ovary> testis respectively. While Cd was accumulated in liver >brain>testis>ovary respectively. The histological study of these organs (Ovary, testes, liver and brain) was recorded. The testis of the fish showed some degenerative changes and decreased number of seminiferous tubules. They appeared empty from different spermatogenic cells. The ovaries showed deformation from their normal shapes and sever lymphocytic infiltration. The liver showed necrosis and aggregation of melanomacrophages (MMCs) The brain also showed degeneration of neurons, severe loss of granular cells and vacuole formation. We recommended improving the quality control of water and environmental monitoring is necessary for these areas.