الفهرس 
Review of literatureOnly 14 pages are availabe for public view
 |  | from | 355 |  |  |
| | | from | 355 | | |
Abstract
One tool to obtain dataon the health of the aquatic ecosystem is the use of bioindicators or biomonitors. The present study aimed to test the validity of the oviparous and viviparous monogeneans of the Nile catfish, Clarias gariepinus as a tool for monitoring some aquatic envionments in the Nile Delta, Egypt. Three differing-water quality ecosystems were studied during the period from October 2015 to September 2016: Damietta Branch of the River Nile, Ammar Drain (Drain No. 2) and Telbanah Drain. Obtained data revealed that: 1) The studied monogenean species varied greatly in their numbers on the catfish host, with the oxygen poor, pungent smell, highly turbid, dirty, shallow and small-sized Telbanah Drain was the most hospitable habitat for these parasites (4907 out of 7098 worms). This deteriorated waterway stored the highest amounts of Ca+2, Mg+2, N2 and and P. On the other hand, the relatively deeper, larger and agriculturally polluted water of Ammar Drain showed the highest levels of pH, EC, TDS, HCO3−, SO4+2, Cl−, Na+, K+ 2) The present findings revealed that only Quadriacanthus species are good biomonitors and sensitive pointers of environmental fluctuations in the aquatic ecosystems; these organisms apparently proliferate in polluted water and stressed fish. 3) The spatial and temporal fluctuations in the monogenean populations of the Nile catfish, Clarias gariepinus were investigated in three differing-water quality environments at the Nile Delta, Egypt. 4) Monogeneans showed considerable variability in their seasonal dynamics from one locality to another. Some monogeneans attained their peak infestation during spring or summer, while others showed their peak infestation during autumn. Moreover, the studied monogeneans showed marked differences in their responses to physicochemical parameters and heavy metal pollutants in different localities. 5) Some monogeneans attained significant preferrence for particular microhabitats on the gills; however other monogeneans were randomly distributed on available microhabitats. 6- Finally, the study recommends to Strict control enforced by laws regulation should be applied over polluted industrial wastewater, agricultural drainage water and sewage water debouches into the River Nile and Lake Manzala. All these sources of water input affect the physiochemical characteristics of water, sediments, biological components, fish production and human health.