الفهرس 
Chapter 1: Introduction and literature reviewOnly 14 pages are availabe for public view
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Abstract
The ecology and vegetation of aquatic macrophytes of four freshwater habitats (River Nile, large irrigation canal, large drain and small drain) at Beni Suef district, were studied. About 14 aquatic plants, mostly angiospermae and representing the three main groups of aquatic plants (free-floating, submerged and floated -leaved or emergent) were identified and their distribution in relation to seasonal variation, was monitored. The distribution and the vegetation density of each species were mainly determined by the type of freshwater and by seasonal variations. The majority of the aquatic plants exhibited a maximum growth rate in summer season in the slow-moving water near banks of each water-body, some plants were observed growing in the fast-moving water, but failed to propagate and never form a population. The submerged aquatic plants in the species Potamogeton crispus were found to be cosmopolitan in distribution, with regards to the type of freshwater
habitat and season. Other aquatic plants, such as the submergent plants Ceratophyllum and Myriophyllum, and the emergent plant Echinochloa, were always dominant or predominant in the various aquatic communities identified. The aquatic free-floating plant Eichhornia also formed dense vegetation, but in drain water and Wetland habitats with shallow water. Dense vegetation of various aquatic plants was found in the Nile and the irrigation canal water, but a more diverse communities of aquatic plants were identified in the large drain (Al-Moheit drain).
The biomass yield for 4 aquatic plants, grow in drain water, was determined monthly. The average highest biomass was produced by Potamogeton pectinatus (105 g dry weight / m ), followed by Lemna gibba (67 g/m2), Ceratophyllum demersum (65 g/m2), and Potamogeton crispus (30 g/m2). The biomass yield showed seasonal variation; while P. crispus and L. gibba produced higher biomass in winter (40 -130 and 166 -212 g/m2), P. pectinatus and C. demersum produced higher biomass (180-185 and 110 -130 g / m2) in summer season, respectively. The bimass of aquatic plants is also affected by interactions and competition between plants, Lemna gibba was cultivated in conjunction with Azolla plants and it was found that growth of Lemna was stimulated when mixed with Azolla in various proportions (1:1,1:3 and 3:1), especially at low temperature (14 °C).
The physical conditions (e.g. water temperature, and contentration of dissolved 02) and chemical canditions (e.g. total soluble salts, pH and the anions CI”, C03~ HC03”and S04”)
were monitored and determined for four fresh-water habitats. The water temperature of Nile water was about 20-30 °C, O2 concentration was about 7-11.5 mg /L, and pH ranged between 7-8 (neutral or slightly alkaline). The total soluble salts in Nile
water ranged between 210-400 ppm, the highest levels were in winter. Anions were in low or medium concentrations, the highest levels were in winter. The physical and chemical environment of Al-lbrahimia canal water was, to some extent, similar to Nile water. However, the environmental conditions in drain water was different from that of Nile and canal water, especially in chemical environment. The concentration of total soluble salts and bicarbonates in drain water was approximately twice that of Nile and canal water. These parameters were in their highest levels in winter and autumn.
The chemical analysis of plant materials from different macrophytes revealed that these plants accumulate higher amounts of the macro-elements (Na, K, Ca and Mg) and lower amounts of the microelements Zn, Mn, Fe, and Cu). No clear differences were found between various aquatic plants with regards to mineral ^content and type of freshwater habitat, with few exceptions. The contents of the essential elements (C, N, H and S) were not greatly different in various aquatic plants. The mineral contents in Nile and canal water were lower than mineral contents of drain water, however, the content of microelements were in trace amounts in Nile water and drain water.
Aquatic macrophytes constitute a vital component of the freshwater ecosystem contributing to the diversity of a healthy Ijuatic environment (Flint and Madsen 1995). The macrophytes act as biological indicators of polluted water and as bio-filters in Hstructed wetlands (Carpenter and Lodge 1986, Jain etal 1989, wacs and Podani 1986, Mortimes 1985). The indicator capacity several species have been revealed^(Grasmuck et al. 1995), ptamogeton pectinatus for eutrophicated waters, and Ranunculus mans for high nitrate level. They aid in nutrient cycling and %de food and habitat for aquatic organisms (Carpenter and ge 1986, Madsen etal. 1996).
’ The aquatic macrophytes in freshwater habitats in Egypt received little attention, their significance in the ecology of freshwater was only indicated in the last two decades. The ecology of hydrophytes in the Cairo and Dilta area have been studied (Abo-lil 1987, El-Fiky 1974). The ecophysiological characterisics of Hie hydrophytes in freshwater at Assiut (Upper Egypt) were recently studied (Saleh 1997). Similarly, the vegetation of the High Bam Lake and the regulated water in the south of Egypt, have been Ramined (Ali 1987, 1992). The ecological significance of some hydrophytes their epiphytic algae in freshwater habitats of Egypt have also been investigated (Abo-Ellil 1991, Ayad 1980). pie taxonomic studies of aquatic macrophytes, in relation to
Aquatic macrophytes constitute a vital component of the freshwater ecosystem contributing to the diversity of a healthy Ijuatic environment (Flint and Madsen 1995). The macrophytes act as biological indicators of polluted water and as bio-filters in Hstructed wetlands (Carpenter and Lodge 1986, Jain etal 1989, wacs and Podani 1986, Mortimes 1985). The indicator capacity several species have been revealed^(Grasmuck et al. 1995), ptamogeton pectinatus for eutrophicated waters, and Ranunculus mans for high nitrate level. They aid in nutrient cycling and %de food and habitat for aquatic organisms (Carpenter and ge 1986, Madsen etal. 1996).
’ The aquatic macrophytes in freshwater habitats in Egypt received little attention, their significance in the ecology of freshwater was only indicated in the last two decades. The ecology of hydrophytes in the Cairo and Dilta area have been studied (Abo-lil 1987, El-Fiky 1974). The ecophysiological characterisics of Hie hydrophytes in freshwater at Assiut (Upper Egypt) were recently studied (Saleh 1997). Similarly, the vegetation of the High Bam Lake and the regulated water in the south of Egypt, have been Ramined (Ali 1987, 1992). The ecological significance of some lydrophytes ar>d their epiphytic algae in freshwater habitats of Egypt have also been investigated (Abo-Ellil 1991, Ayad 1980). pie taxonomic studies of aquatic macrophytes, in relation to
!no longer necessary, a factor which has been found to cause an increase in the densities of freshwater hydrophytes in the Nile system (Zahran and Willis 1992). The extensive growth of aquatic weeds (dense vegetation) in the Nile System freshwater of Egypt is represents an ecological problem, mis dense vegetation interferes with irrigation and hydroelectric schemes, fisheries, or navigation i 1992).
The aquatic flora in the freshwater habitats of Beni-Suef
Bistrict (Middle Egypt) have never been studied before. Therefore,
this study was devoted to investigate the ecological significance and
Rrersiry of aquatic macrophytes in the freshwater systems of the
district. The interrelationships between various macrophytes and their distribution in relation to water environment and chemistry were examined. The biomass production and the mineral content of these aquatic macrophytes were also determined. This chapter was allocated to macrophytic angiospermae (Flowering plants), the Mtic fem Azolla, which is spreading recently in freshwater of the district , will be studied separately (Chapter four).