الفهرس 
ContentsOnly 14 pages are availabe for public view
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Abstract
The River Nile and its primary tributaries such as Mansouria Canal are considered to be the life artery of the Egyptian society. Mansouria Canal originates from the main stream of the River Nile south to region of Cairo, travels northwards at the eastern border of the Nile Delta and terminates in Manzala Lake and the Mediterranean Coast at Gamasa City. Similar to the freshwater ecosystems of the Nile Delta, Mansouria Canal is exposed to many human interventions that in turn altered the nature of water and degraded the health of aquatic ecosystem as a whole. Of these pollution sources, heavy metals and abundance of the cattle egret were the most relevant. Earlier in September and onwards, Mansouria Canal faced the challenge of irregular bouts of filling and loss of water. To verify these aims:- The present study was conducted to observe monthly changes of the physicochemical environmental parameters of water over the breeding time of the Nile green tilapia, Tilapia zilli dwelling Mansouria Canal, in the vicinity of Salaka Village, Mansoura, Egypt. The present study aimed also to document the reproductive behaviour of this fish kind by field observations and close inspection on the behavior of breeding (nest-building) and non-breeding (nest-free) forms in its natural environment, along the shoreline of Mansouria Canal. The present investigation dealt with the clarification of the relationship between abiotic factors (e.g. pH, temperature, electrical conductivity, dissolved oxygen, chlorides, sulphates, bicarbonates, ammonia, total phosphorus, sodium, potassium, calcium and magnesium, and some heavy metals such as iron, zinc, lead, cadmium, manganese and chromium in water, and biotic factors in fish (host gender and condition factor: weight and length) on the one hand, and infection variables (prevalence, mean intensity, abundance) on the other hand. Furthermore, influences of the breeding aspects on a range of blood and biochemical parameters such as complete blood picture, biochemical enzymes like CAT, MDA, GST and GSH, and sex hormones (Testosterone and Estrogen) and bactericidal activity, were evaluate, with reference to corresponding aspects in non-breeding forms. The results show that:- In the light of the present findings, higher monogenean infestations were documented on host individuals obtaining lower condition factor (factor-I). In contrast, host individuals belonging to the condition factor-III were free or almost free of monogenean parasites. These results signpost a probable influence of monogenean infestation on the physical status and general health condition of fish host. However, the lifestyle and behavioural aspects of monogenean parasites should be considered. First, monogeneans of the genus: Cichildogyrus possess noticeably small size. Second, meals drawn by these tiny organisms are limited and may not seriously alter the body condition of green tilapia. Third, the number of monogenean worms (337) encountered on the cichlid host (150 individuals) seems likely to reflect a light infestation pattern. from our results it is concluded that: Prohibiting fishing of T. zilli from April to Augu Establishing or designing a protective net and around the spawning grounds to confirm safe breeding in the absence of predators and irritants. Outspreading the spawning grounds on sheltered regions in order to provide more grounds for nesting mates. Transfer of trees far from the edges of the Mansoura canal and the breeding grounds of green tilapia. Getting rid of inshore contaminants prior to the beginning of the spawning period. Stricting enforcement of environmental laws.