الفهرس 
Introduction and Aim of the workOnly 14 pages are availabe for public view
 |  | from | 151 |  |  |
| | | from | 151 | | |
Abstract
Brine shrimp of genus Artemia (Crustacea) are of interest to both biologists studying their evolution and developmental biology and aquaculturists using them as live food in fish larviculture. Also, Artemia was used for toxicity screening tests of some plant extracts. Artemia had
the ability of heavy metals accumulation so it considered as biomonitor
for environmental pollution. Considering the lack of ecological and
biological information relative to the brine shrimp Artemia salina in EL
Hamra saline Lake, Wadi El- Natrun. So the present work was aimed to
study the following aspects:
1- Field studies with the following objectives:
The samples of Artemia salina were collected monthly during the period
of one year ( starting from March 2010 to February 2011).
Study some of abiotic characteristics of the surrounding environment of
Artemia salina, such as temperature, salinity and pH of water of the
lake. Investigation of the effect of the seasonal variation on the density of
Artemia salina sex ratio, number of cysts and some morphometric
parameters.Study the role of Artemia salina as biomonitor of pollution by
the analysis of some heavy metals in the tissue of Artemia salina, water
and sediment of the Lake.
2- Experimental studies with the following objectives:
Study the impact of salinity on survival rate, body length, morphometery,
hatchability and external structures of Artemia salina using Scanning
Electron Microscope. Effect of heavy metals Cd and Fe on the activity of
the antioxidant enzymes, the concenteration of metallothioneins protein
and total protein pattern of Artemia salina.
Summary and conclusions
97
The obtained results can be summarized as following:
Part (1): Field studies
1.1. The mean values of abiotic factors in El Hamra Lake during the
period of investigation (March 2011-February 2012)
El Hamra Lake is morphologically passed through two seasons.
The first one includes Winter and Spring; which is characterized by large
amount of water and population of Artemia. The scond one included
Summer and Autumn seasons, and characterized by very small amount or
no water and little to no population of Artemia (Dry season). In this
season the Lake surface covered by thick layer of brine.
Air and water temperature, pH and salinity were recorded monthly.
The water temperatures ranged between 14 ± 0.1 - 27 ± 0.05°C in
January and August, respectively. The air temperatures were ranged
between 17 ± 0.3 - 38 ± 0.1°C in January and August, respectively.
Monthly average of pH values were ranged between 8.5± 0.1 - 9.8 ± 0.05
in February and September, respectively. The mean values of minimum
and maximum salinity were 180 ± 1.1and 480 ± 1.5 g/l in January and
September, respectively.
1.2. Population density of Artemia salina in El Hamra Lake during
the period of investigation (March 2011- February 2012)
The mean number of monthly collected individuals were ranged
between 250 ± 0.7 individuals/l in June and 500 ± 0.8 individual/l in
February. Females were predominated than males during the year. The
individuals were completely absent in the period of July to December
(Dry season). The mean number of nauplii in December was 450 ± 0.7
nauplius/l, they declined progressively and remain at a minimum level
during April (30 ± 0.4 nauplius/l) and were completely absent from May
Summary and conclusions
98
to November. The mean number of cysts ranged between 20 ± 0.4 in
April and 850 ± 1.1 cysts / l in September.
1.3. Effect of seasonal variations of abiotic factors on the
morphometery of Artemia salina during the period of investigation
(March 2011- February 2012)
The morphometric measurements fluctuated according to the
environmental conditions and they varied between males and females.
The length of abdomen increased significantly in male (3.6 ± 0.4 mm) in
April. The width of thorax increased in females when compared to males
in January (2.6±0.4 mm), February (2.7±0.6 mm) and March (2.8±0.4
mm). The length of thorax increased in females (3.5±0.5 mm) than males
(3.2 ± 0.4 mm) in March. The length of body showed increase at the
January (6.2±0.7 mm), February (6.3±0.6 mm) and March (7.4 ± 0.8 mm)
in females than males.
1.4. Seasonal variation of metal concentrations in the tissue of
Artemia salina, sediment and water during the period of investigation
(March 2011- February 2012)
The concentrations of the metals in the tissue of Artemia were
ordered as the following Fe > Zn > Pb > Cu > Cd. Metals concentrations
in the sediment were ordered as the following: Fe > Cu > Zn > Pb > Cd.
Metals concentrations in the water were ordered as follow Fe > Pb > Cd >
Cu > Zn. Fe was the highest metal in the sediment (24.3 ± 1.5 mg/l),
tissue (4.2 ± 0.2 mg/l) and water (2.3 ± 0.01 mg/l).
The highest concenteration of Na was in the water (4452 ± 6.5
mg/l) in August, followed by sediment (18 ± 0.5 mg/l) in May. The
lowest Na concentration was recorded in tissue of Artemia (14.5 ± 0.9
mg/l).
Summary and conclusions
99
Part (2): Laboratory studies
2.1. Effect of different concentrations of salinity on biology of
Artemia salina
After the application of different concentrations of salinities for 7
days, both concenterations, the hypersaline and hyposaline
concenterations caused 77% and 70% reduction of survival rate of
Artemia salina at 3rd day, respectively when compared to the control. At
7th day, the hypersaline and hyposaline concentrations caused 100% and
90 % reduction, respectively. The hyposaline concentration caused
significant decrease of the body length in all time points of the
experiment. At 7th day, the length of body was (5.1 ± 0.1mm) when
compared to the control one (7.2 ± 0.05 mm). The hypersaline
concenteration caused significant decrease in all time points of the
experiment. At 7th day, the length of body was (4.3 ± 0.1 mm) if
compared to control (7.2 ± 0.05 mm). In comparison, the decrease of
body length of Artemia was greater at the hypersaline concenteration
than hyposaline one.
The two concenterations caused alteration on the morphometery of
both males and females. The hyposaline concenteration increased the
width of thorax in male (2.7 ± 0.05 mm) and female (2.6 ± 0.1mm) when
compared to the control values 2.1 ± 0.05 and 2.2 ± 0.05 mm,
respecteively at the 1st day. At the end of the experiment, both
concenterations decreased the length of thorax and abdomen in males.
The length of thorax was 2.7 ± 0.05 mm in hyposaline, 2 ± 0.1mm in
hpersaline and the control (3.8 ± 0.05 mm). The length of abdomen was
2 ± 0.1 mm in hyposaline, 1.9 ± 0.05 mm in hpersaline and the control
(3.1 ± 0.05 mm). Ratio of abdominal length/total length was decreased in
hyposaline and hypersaline concenterations at 1st day in both males and
Summary and conclusions
100
females. At the 7th day, the ratio appeared larger than in the control
specimens in males (44%) and females (53%) when compared to the
control values 43% and 43%, respectively at the hypersaline
concnteration. Hatchability at hyposaline group was reduced to 6 % and
ceased to reach 0 % at hypersaline group when compared to the control
one, which was 100 %.
Adult Artemia salina exihibited different morphological alterations
to regulate both hyposaline and hypersaline media. The surface of
branchiae, the maxillary gland and metepodites became more folded in
the hypersaline concenteration. Meanwhile, in the hyposaline media, it
became nearly flattened when compared to that of the control. Size of
eye showed difference in both concenterations in comparsion to the
control. The hypersaline concenteration caused reduction in the size of
the eyes while the hyposaline one increased their size.