الفهرس 
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Abstract
Lake Manzala is the largest of Egyptian lakes along the Mediterranean coast. Representing a highly dynamic aquatic system, that has been undergoing continuous and pronounced changes, most of the water entering the lakes comes from the canals and drains ditches from the southern, southeastern and northwestern regions. This inflowing water provides the lake with high nutrient loading, causing eutrophic conditions and high productivity. At the beginning of the twentieth century the lake covered some 1,698 km². However, ambitious land reclamation projects had reduced the size of the lake to 905 km² by 1981 and to 770 km² by 1988. It is predicted that existing reclamation plans will reduce its area further to 469 km². Encroachment from adjacent urban centers is threatening to reduce the area of the lake even further. Since the construction of the High Dam and the almost complete cessation of sedimentation, the coasts of the eastern delta have altered from predominantly accretional to erosional. These activities have increased the pollution of the lake.The lake is affected by various external factors, the most important of which are, the progressive increase of industrial and agricultural wastewater discharge. These pollutants are damaging to aquatic organisms specially fishes. It is doubted that the aquatic environment is capable of absorbing the effects of these pollutants without being detrimental to the living resources. The results of the current study indicated a deteriorating water quality of Lake Manzala based on the water quality index categorization.
This study aimed to investigate the link between the contaminated status of Lake Manzala and the response of Chironomus sp., on molecular and morphological levels, in order to enhance the use of these deformities as a bioindicator of environmental health. The sampling stations were chosen to cover the southern sector of Lake Manzala and its inflowing drains. Water of study area is subjected to pollution via several and rather complicated routes; among them domestic, industrial and agricultural discharges are the most significant. Hadous drain has typical agricultural drainage water, which would be of moderate quality for agricultural use. However, water from Bahr El-Baqar, is quite different, Bahr El-Baqar serves as a wastewater stabilizing facility for Cairo sewage, allowing this wastewater to become biologically degraded into nutrient-rich by the time it reaches the lake. El-Matariya is Middle Eastern part of the Lake with extensive fishery activities.