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العنوان
ECOLOGICAL AND BIOLOGICAL STUDIES ON ALGAL COMMUNITIES OF SOME REGIONS OF WADI EL-RAYAN,EGYPT /
المؤلف
HASSAN, SHERIF HASSAN MOHAMED.
هيئة الاعداد
باحث / شريف حسن محمد حسن
مشرف / إمام عبده الإمام قبيه
مشرف / علا حموده إبراهيم
مشرف / محمد سيد عبد الحميد
الموضوع
Algae.
تاريخ النشر
2005.
عدد الصفحات
8, 217 Leaves :
اللغة
الإنجليزية
الدرجة
الدكتوراه
التخصص
علم الأحياء الدقيقة
تاريخ الإجازة
23/12/2005
مكان الإجازة
اتحاد مكتبات الجامعات المصرية - النبات
الفهرس
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Abstract

Egypt is one of the developing countries which is exposed and affected by different environmental pollutants. The ecological effects of these pollutants on the natural ecosystems especially the algal communities need to be monitored continuously.
Wadi El-Rayan is one of the most popular protected areas in Egypt, and considered as par excellence the most arid among the desert regions of the world.
Human impacts were the main threat to this natural area and the efficient control over these activities in is one of the main topics for the [Egyptian government. This takes place through some strategies and [approaches to protect and expand the available natural resources base: jaiming to increase productivity, reduce migration and improve the living condition in this area. One of the main points to achieve the previous approach is surveying the living organisms that could tolerate the anthropogenic activities.
• In this investigation, three locations along the second lake shore of I Wadi El-Rayan were chosen, each location including three different I habitats designated as water and wet and dry soil, and classified to 36
stands.
• These stands were monitored seasonally to record the variation in [ their physicochemical characters and each stand was studied
qualitatively and quantitatively for its algal community’s content during the different seasons.
» The physicochemical characters of the soil samples revealed that, pH was slightly alkaline and ranged between 7.6-8.1 and 7.3-8.3 of wet
t and dry soil types, respectively. While it recorded 8.22-8.77 in the water samples during the different seasons.
The maximum moisture content of the wet soil samples was recorded during autumn and winter seasons (25.3 and 22.3%, respectively), while it was very low and more or less similar among the other seasons.
Both wet and dry soil types were poor in the organic carbon content during all seasons.
Seven heavy metals (Cu, Co, Mn, Ni, Zn, Fe and Pb) were monitored seasonally in the soil samples. The wet soil samples recorded high cobalt content during summer, in contrast it was not detectable during the winter season. Copper recorded its maximum value during autumn. The dry soil type recorded its highest content of cobalt during winter and autumn, whereas lead recorded maximum limits in spring and summer.
1 Eight algal species were identified in the wet and dry soil habitats; I those were belonging to Cyanophyta (six species) and Chlorophyta :(two species). Cyanophyta was detected in high percentage than Chlorophyta to reach 96% during all seasons in the wet soil habitat.
A total of 69 species belonging to four algal phyla (35 Bacillariophyta, 19 Cyanophyta, 13 Chlorophyta and only two belonging to Euglenophyta) were identified in the water habitat Bacillariophyta were dominant during winter and spring, Cyanophyta
dominated during summer season and Chloropyhta reached its highest species number during spring and summer seasons.
The application of TWINSPAN classification technique led to the recognition of 8 algal vegetation groups, each group included a set of stands which were similar in their habitat and characterized by
indicator species.
All TWINSPAN soil groups (four groups, from group I-IV) were characterized by low content of organic carbon, no significant difference were observed in soil pH which lied in the alkaline side. No significant differences were observed in soil texture fractions during the investigation period among the different soil groups except the silt fraction which was significantly different
Grjpup I comprised two stands dominated by Anabaena wisconsinense and Chlorella vulgaris. Group II comprised 6 stands and Anabaena wisconsinense was the indicator species. Group III included 11 stands indicated by Chroococcus limnneticus and OscUIaxoria Hamelii. Group IV comprised 3 stands indicated by Anabaena Bometiana.
The results revealed significant differences between the different water groups in sulfate and chloride contents. Sulfate was the highest anion followed by the chloride this was reflected on the salinity value which recorded 2%. The water samples recorded detectable concentrations of cobalt, copper and nickel with averages of 0.21, 0.1 and 0.08ppm, respectively.
In general, the results revealed seasonal variations in physicochemical characteristics of the lake which could be attributed to the discharges of different drains into the lake
density (62.6, 59.5, 64, 83 and 78.4%, respectively), cell count (75.7, 70,60,97 and 88%, respectively) and chlorophyll a content (92, 86.7, 68, 96.6 and 85%, respectively) of Anacystis sp.
• Low concentrations of each Ni (1.5ppm), Co (lppm), Cu (0.02ppm) and Hg (0.004ppm) stimulated significantly the total soluble carbohydrates of Anacystis sp. by maximum increasing values of 95.6, 59, 43 and 42.8%, respectively, as compared with the control. At the same time, the total soluble proteins of Anacystis increased significantly by 158, 72, 81 and 99%, respectively, under the [ treatment by the previous concentrations of the selected metals.
f Meanwhile, higher doses of the selected heavy metals induced high I significant reduction in both total soluble carbohydrates and total
I soluble proteins of Anacystis sp.
!• The total soluble carbohydrates was reduced significantly by 43, 38, [ 47.6 and 47% under the treatment by Ni (12ppmX Co (10.5ppm), Cu (8ppm) and Hg (0.027ppm), respectively. Similar partem was
observed in case of total soluble proteins, where it was depressed significantly under the same doses by 57, 63.4, 50 and 85%, I respectively, as compared with the control.
p Similar pattern was observed in case of growth parameters of t Dunaliella sp. as mentioned in Anacystis sp. But the concentrations of ( the heavy metals and sodium chloride which were required for I stimulation or inhibition of Dunaliella were very higher than that required for Anacystis.
I Low concentrations of each Ni (15ppm), Co (lOppm), Cu (3.5ppm), [ Hg (0.04ppm) and NaCl (2 ML”1) induced significant stimulation invvv
Classification analysis by TWINSPAN successfully clarified that group V belonged to winter season and dominanted by Pinmdaria gibba. The five stands of group VI represent winter and summer seasons and indicated by Gloeothece rupestris and Merismopedia elegans var. major. Group VII comprised three stands belonging to the spring season dominated by Ankistrodesmus falcatus var. tumidus and Oscillatoria tenuis var. tergestina. Group VIII was represented by three stands belonging to autumn season with indicator species Chroococcus limneticus and Nitzschia radicula.
The preliminary studies on growth tolerance of the recorded algal species against two stressors (heavy metals and salinity) showed that the cyanobacterium Anacystis sp. and the green alga Dunaliella sp.
were the most resistant algal species.
The present investigation studied the effect of the selected heavy metals (Ni, Co, Cu and Hg) and salinity at two concentrations one of them was stimulator (low concentration) and the other was inhibitor
(high concentration).
Low concentrations of each Ni (1.5ppm), Co (lppm), Cu (0.02ppm), Hg (0.004ppm) and NaCl (0.5ML-1) induced significant stimulation in the-different growth parameters and recorded the maximum increase in optical density (23, 60,38,24 and 33.7%, respectively), cell count (84, 85, 13,32.7 and 42%, respectively) and chlorophyll a content (99,104,60, 84 and 38%, respectively) of Anacystis sp.
On the other hand, Ni (12ppm), Co (10.5ppm), Cu (8ppm), Hg (0.027ppm) and NaCI (1.4ML”1) induced significant inhibition in the growth parameters and recorded the maximum reduction in optical
the different growth parameters and recorded the maximum stimulation in optical density (30.7, 24,27, 64 and 85%, respectively), cell count (60.7, 36, 35, 185 and 94%, respectively) and chlorophyll a content (62,44, 54,97 and 430 %, respectively) of Dunaliella sp.
Due to increasing the concentrations of Ni (35ppm), Co (18ppm), Cu (18ppm), Hg (0.35ppm) and NaCl (3.5ML”1) significant reduction in all growth parameters were induced and recorded the maximum inhibition in optical density (42.3, 90, 57,66 and 49%, respectively), cell count (60.7, 98, 81, 83 and 57%, respectivery) and chlorophyll a content (78.8,98,66,66 and 49%, respectively).
Low concentrations of each Ni (15ppm), Co (lOppm), Cu (3.5ppm) and Hg (0.04ppm) stimulated significantly the total soluble carbohydrates of Dunaliella sp. by maximum increasing values of 44.5, 55, 30 and 30%, respectivery, as compared with the control. At the same time, the total soluble proteins of Dunaliella increased significantly by 67, 17,47 and 70%, respectively, under the treatment by the previous concentrations of die selected metals.
However higher doses of the selected heavy metals induced high significant reduction in both total soluble carbohydrates and total soluble proteins of Dunaliella sp.
The total soluble carbohydrates was reduced significantly by 42, 66, 60 and 72.8% under the treatment by Ni (35ppm), Co (18ppm), Cu (18ppm) and Hg (0.35ppmX respectivery. Similar pattern was observed in case of total soluble proteins, where it depressed significantly under the same doses by 75, 85, 59 and 94%, respectively, as compared with the control.
Sodium chloride at low concentrations (0.5 and 2 ML”1) produced significant stimulation on the total soluble carbohydrates of both Anacystis and Dunaliella spp. by increasing values of 87.8 and 36%, respectively. Meanwhile, at higher concentrations (1.4 and 3J5 ML”1) the carbohydrates inhibited significantly by 47 and 64% of Anacystis and Dunaliella spp., respectively.
The total soluble proteins of Anacystis and Dunaliella increased gradually to reach its maximum stimulation (67.4 and 189.6%) under the treatment by NaCl (0.5 and 2 ML_IX respectively, as compared with the untreated cultures. On the other hand, by increasing sodium chloride concentration to 1.4 and 3.5 ML”1, the total soluble proteins reduced significantly to reach its maximum inhibition 733 and 40%, of both Anacystis and Dunaliella, respectively.
All of the treatments by the studied heavy metals induced an increase in the proline production, except Cu (8ppm) in case of Anacystis sp. meanwhile in case of Dunaliella sp., only Co (18ppm) stimulated the production of proline. At the same time Ni (12ppm). Co (10.5ppm) and Cu (8ppm) moderately stimulated the biosynthesis of alanine, and highly stimulated valine and suliur containing amino acids (methionine and cystine) in Anacystis sp. The pronounced stimulation of cystine in response to Cu (18ppm) treatment of Dunaliella sp. was found to be associated with stimulation in both glycine and glutamic acid contents.
It was obvious that the unsaturated fatty acids production of Anacystis sp., were inhibited significantly under the treatment by copper (8ppm) followed by cobalt (10.5ppm), mercury (0.027ppm) and nickel
(12ppm), these inhibitions recorded 17.5, 12.4, 9.8 and 3.8%, respectively, as compared with the control.
• On the other hand, the unsaturated fatty acids of Dunaliella sp., were stimulated by 122%, as compared with the control, under the stress by 3.5 ML”1 NaCl. Meanwhile, 1.4 ML”1 NaCl reduced the unsaturated fatty acids production by 5.5% in case of Anacystis sp.
• The structural damage due to exposure to stresses was distinctly different in the two studied algal species. All of the studied stresses induced obviously different deformation in the cellular ultrastructures. The main target of the deformation was thylakoid lamellae of Anacystis cell and chloroplast and the nucleus of Dunaliella cell structure. Whereas, cell structure of Dunaliella was riot affected dramatically when treate.