الفهرس 
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Abstract
Qarun Lake is one of the most important inland aquatic
ecosystems in Egypt because of its historical and scientifically
importance to study its unique ecosystem. The lake receives the
agricultural drainage water from the surrounding cultivated land.
The drainage water reaches the lake by two main drains, El-Batts
drain and El-Wadi drain. Water effluent to lake has different
types of heavy metals. These heavy metals cause the deterioration
of ecosystem.
The purpose of the present field comparative investigations
was to determine the effects of water quality of Lake Qarun using
a suite of biomarkers; morphological, oxidative stress,
genotoxicity, stress proteins and histological studies in Solea
aegyptiaca fish on seasonal basis (during winter and summer
seasons). Then, the integrated biomarker response (IBR) index
was used to improve the discriminatory power of the adopted
multi-biomarker strategy.
Samples of water and fish were collected from four different
studied sites along Lake Qarun. The first site (western sector) and
the second site (northern sector) are away from any source of
pollution, while the third site (midpoint of the southern sector of
the lake) and the fourth site (eastern sector of the lake) are
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exposed to effluents discharged directly from El-Wadi and ElBats drainage channels, respectively.
Water quality
Physical parameters: for air and water temperature,
salinity, electrical conductivity and total dissolved solids the
highest value was recorded in the western and northern sectors of
the lake during summer and the lowest value was recorded in the
eastern and southern sector during winter. While, pH showed the
highest value in eastern and southern sectors during summer and
the lowest value in western and northern sectors during winter.
On the other hand, the highest transparency value was detected
during winter in the western sector and the lowest value was
recorded during summer in eastern sector.
Chemical parameters: dissolved oxygen recorded the
higher value in the western sector during winter and lower value
in eastern sector during summer. Meanwhile, biological oxygen
demand, chemical oxygen demand and total alkalinity showed the
maximum value in eastern and southern sectors during summer
and the minimum value in western sector during winter.
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Nutrient salts: for ammonia, nitrite and nitrate the highest
concentration was recorded during summer season in eastern and
southern sectors. While, the lowest concentration was detected
during winter season in western sector.
Water heavy metals
Concentration of heavy metals (Iron, Copper, Zinc and
Lead) showed the highest value in water samples from the eastern
and southern sectors of the lake during summer and the lowest
value in the northern and western sectors during winter. On the
other hand, concentration of (Cadmium and Nickel) was higher
during winter in water samples from eastern sector for cadmium
and southern sector for nickel and lower during summer in the
western sector of the lake.
Residual heavy metals, Bioaccumulation factor and Metal
pollution index in gills, liver and muscles
All the studied heavy metals showed the highest
concentration in gills, liver and muscles of the Solea aegyptiaca
collected from the eastern and southern sectors of the lake during
summer season, except nickel in liver and copper in muscles that
showed the highest concentration in both winter and summer
seasons. Also, all the heavy metals showed the lowest
concentration in western and northern sectors during winter,
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except copper and lead in gills and muscles and nickel in liver
that showed the lowest value during summer season. Furthermore,
zinc, lead and nickel had favorable bioaccumulation pattern in gill
tissues, while iron, copper and cadmium were mainly higher in
liver. Meanwhile, the lowest bioaccumulation values of all
studied metals were recorded in muscle tissues. In addition, the
highest metal pollution index in gills, liver and muscles was that
for fishes collected during summer from the eastern sector, while
the least was that for fishes collected from western sector during
summer for gills and winter for liver and muscles.
Growth parameters
The highest mean value of the weight, the length and
hepatosomatic index was recorded in fish collected from the
northern and western sectors of the lake and the lowest mean
value was recorded in fish of the eastern and southern sectors.
While, for the condition factor, the highest mean value was
recorded in fish collected from the eastern and southern sectors
and the lowest mean value was recorded in fish of the northern
and western sectors. The results revealed that that there was a
significant difference between seasons and the winter season was
recorded the highest value of fish weight and length, while the
summer showed the highest condition factor and hepatosomatic
index.
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278
Oxidative stress parameters
The highest mean value of TAC in gills, liver and muscles
was recorded in fish collected from western sector, while the
lowest mean value was recorded in eastern and southern sectors.
However, the maximum mean value of MDA, PC, 8-OHdG and
DNA strand breaks in gills, liver and muscles was detected in the
eastern and southern sectors and the minimum mean value was
detected in the western and northern sectors. Moreover, TAC
showed no significant difference between winter and summer
seasons, while, MDA, PC, 8-OHdG and DNA strand breaks
revealed a significant difference between seasons with the highest
mean value in gills, liver and muscles during winter season.
Stress proteins
The highest mean value of MT and HSP70 was reported in
gills, liver and muscle samples collected from the eastern and
southern sectors and the lowest mean value was detected in
samples from the western and northern sectors. Also, MT and
HSP70 in gills, liver and muscles showed a significant difference
between seasons with the highest mean value during winter
season.
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279
Integrated biomarker response index
Winter season showed higher IBR scores. The eastern sector
had the highest IBR value followed by the southern sector being
the most polluted sites in direct contact with sewage and
agricultural contaminants from El-Bats and El-Wadi drainage
channels. Increased gills MDA, liver PC, gills and liver HSP70,
liver MT, gills 8-OHdG and gills, liver and muscles DNA strand
breaks were the most discriminant factors for the eastern sector,
while variations in MDA level in gills and PC and MT
concentrations in liver, were the most relevant responses in
southern sector. The maximum IBR value was detected in liver
followed by gills, while muscles showed suppression.
Histological studies
Histopathological alternations and clear damage were
obvious in gills, livers and muscles of fish collected from the
eastern and southern sites that exposed to different sources of
pollution.
In conclusion, the present study showed that the utility of an
integrative approach based on fish biomarkers represents a
sensitive and effective tool reflecting the environmental status of
the aquatic environment. Moreover, the analyzed responses are
associated with seasonality and Solea aegyptiaca exhibited the
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280
strongest variations in winter when spawning occurs.
Additionally, IBR analysis was able to compare among seasons,
sites and organs based on integrating biomarkers responses and
revealed that the alterations observed related well with the levels
of environmental contaminants, demonstrating the effectiveness
of this biomonitoring approach.