HEAVY METALS CONTENT AND WATER QUALITY OF LAKE MARYOUT AND THEIR IMPACTS ON TILAPIA CONTAMINATION AND PHYSIOLOGY

The aim of the present wort is to assess water quality. heavy metals content
in lake Maryout water and in edible muscles of OreochromJs sureus, and to study the
impact of pollution stress on fish body characteristics and physiology. There is no
significant difference among the mean water selenium contents in the four basins. The
overall average of selenium over the lake was 0.08 IJg I I. The northwest basin
contains the highest water lead content (5.99 ± 0.37 IIg I I). The highest water
cadmium and Iron levels were recorded in samples of the main basin (1.6 ± 0.10 IJg 'I
and 1.21 ± 0.09 mg II respectively) while the lowest cadmium level was recorded at
the fishery basin (0.44 ± 0.21119 I I). The southeastern basin showed the highest
arsenic leve! (0.38 ;t 0.15 1)9 I I). The fishery and the soulheasl basins showed the
highest chromium levels (11.13 ± 0.76 and 10.94 % 0.2 IJg II. respectively). The
fishery basin was found to contain the highest nickel eontent (15.22 ± 1.02 )Jg f I).
while the southeast basin showed the lowest nickel level (6.87 t 0.51 Ilg II). The
highest water copper was recorded in fishery basin (8.53 :I: 0.20 IJg f I). The pH of the
main basin showed the lowest values with a . mean 01 7.11:1: 0.18. Sulfides values
recorded at the main basin were drastically variable (0.0 - 14.2) with a mean of 4.48 %
0.86 mg f I. The highest sulfate level was recorded at the fishery and the northwest
basins (1870.6 % 170.7 and 1846 ± 140.6 mg II, respectively). The lowest sulfate
value was recorded at the main basin (631.9 t 36.4 mg II). The highest fish muscle
lead content was observed in the southeast basin (23.97 % 5.15 Ilg I kg) and the
lowest was recorded In the northwestern (3.83 % 1.28 Ilg I kg). There were no
significant differences in the mean cadmium. arsenic and nickel contents in
OnJochromis BUf'llUS muscles of the four basins. The highest chromium conlenl was
found in fish muscles of the southeast basin (754.9 % 19.2 IJg I kg). The highest
Copper contents were recorded in fish muscles of southeast and the northwest basins
(481.5%10.64 and 470.4 %8.22 ~g f kg, respectively). The highest muscles iron conlent
was recorded in fish muscles of :he northwest and the main basin (313.4 % 3.39 and
311.4 % 2.87 mg I kg respedively). Fish caught from the main basin and from the
nshery basin showed signifICantly higher condiUon factor than those caught from the
northeast and southeast basins. The highest moisture content was noticed in nesh of
main basin. The highest protein percent was recorded in fish muscles of the fishery
basin. There were no significant differences in hepatosomatic indices of fish or the
four basins. Fish caught from the southeast basin showed the hiohest relative gall
bladder wei9hts. Fish of the southeast basin showed the highest activity 0' liverl
(GOT). (GPT), and (ALP) followed by those of the main basin and the northwest
basin. The fishery basin lilapia exhibited the lowesl activllles of lhe three mentioned
enzymes. The main basin tilapla showed the least brain (AChE) activity of the enzyme
followed by thOse of the Southeast basin The highest (AChE) activity was recorded
at the nOflhweSI basin.