الفهرس 
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Abstract
The present study aimed to determine variability in phytoplankton distribution, abundance and community structure in relation to physico-chemical properties in various fresh water ecosystem (polluted and non-polluted sites at Minia-Egypt), and to study the effect of various concentrations of heavy metals (Cu2+ and Fe3+) on the growth and some metabolites of some isolated algae (Chlorella ellipsoidea and Scenedesmus subsicatus). As well as, to assess the phycoremediation potential of Chlorella ellipsoidea and Scenedesmus subsicatus for Cu2+ and Fe3+ ions using the Langmuir, Freundlish, Temkin and Dubinin–Radushkevich isotherm constants.
This study showed the following results:
I- Distribution and diversity of microalgae:
1- Water samples from fourteen sites were collected seasonally from July 2017 to May 2018.
2- The physico-chemical analysis of water samples showed that, water temperature has been found to vary between 19 and 34oC. The highest pH value was recorded during autumn at site 4 (Tuna drain) and the lowest was recorded during summer at site 11 (Al-Muheit drain). The electrical conductivity and total dissolved solids fluctuated within 247 µmho.cm-1 and 176.1 mg/L during summer at site 9 and 1145 µmho.cm-1, and 816.4 mg/L during winter at site 10, respectively. The content of total alkalinity ranged between 107.5 mg/L at site 5 during summer and 385 mg/L at site 11 during winter. Nitrate- nitrogen showed the maximum content during winter at site 7, whereas the minimum content was recorded in summer at site 12. Phosphate-phosphorus was fluctuated within 0.05 mg/L at site 8 and 9 to 22.9 mg/L at site 11 during summer and winter, respectively. Content of chloride in the water samples ranged between 35.5 mg/L at site 5 in summer and 230.5 mg/L at site 10 in autumn and winter. On the other hand, the high content of sodium was recorded at site 3 in spring while, the lowest content was recorded at site 2 and 5 in summer. Potassium concentration was the highest in winter at site 11 (Al-Muheit Drain) and the lowest in summer at site 7 (Kab-kab Drain). Calcium content was seasonally ranged between 116 mg/L at site 7 and 31.9 mg/L at site 2 during summer and autumn, respectively. Whereas, the maximum value of magnesium was at site 10 and the minimum was recorded at site 9 in winter and summer, respectively. The highest value of dissolved oxygen was at site 10 in autumn and was not detected at site 11 in all seasons. The maximum value of biological oxygen demand was at site 10 in autumn, and was not detected at site 11 in all seasons. The content of ammonia was only detected at site 11 in summer, autumn, winter and spring. Sulfate-sulfur concentration ranged between 0.23 mg/L during winter at site 9 and 2.4 mg/L during summer at site 13 and 14. The turbidity was high at site 11 and the low value was recorded at site 14 in autumn and winter, respectively.
3- The maximum algal biomass (2803.5 µg/L) was recorded at site 12 in spring; and the minimum (26.7 µg/L) was recorded at site 9 and site 10 in winter.
4- In total, 178 algal species were identified, of which 93 species (20 genera) belong to Bacillariophyceae, 56 species (28 genera) belong to Chlorophyceae, 12 species (9 genera) belong to Cyanophyceae, 9 species (2 genera) belong to Euglenophyceae, 6 species (2 genera) belong to charophyceae and 2 species (1 genus) belong to Dinophyceae.
5- Bacillariophyceae was the most dominant algal group (52.25%) during the four seasons, followed by Chlorophyceae (31.46%), Cyanophyceae (6.74%), Euglenophyceae (5.06%), charophyceae (3.37%) and Dinophyceae (1.12%).
6- The highest number of microalgal species was 80 species recorded at site 3 in spring, while the lowest total number was recorded at site 1 (22 species) in summer.
7- The highest total algal count expressed as individuals was 50120 ind. x103 L-1 that recorded at site 13 during autumn, but the lowest one (2700 ind. x103 L-1) was recorded at site 1 in summer.
8- Oscillatoria limosa, Scenedesmus quadricauda, Cyclotella striata, Euglena proxima, Staurastrum chaetoceras and Peridinium lomnicki were the most abundant species.
9- The diversity indices such as Margalef’s Index (d’), Shannon-Wiener diversity (H’, loge based), Pielou’s evenness (J’), Fisher’s Index (α), Simpson Dominance index (D), Simpson’s Diversity Index (1-D) and Berger-Parker index (d) were studied based on the abundance of algae
10- Margalef’s index showed that phytoplankton diversity was highest (8.4) at site 3 in spring, while the least diversity (2.66) was recorded at site 1 in summer. The maximum value of Pielou’s Evenness index (0.88) was estimated at site 10 in spring, whereas the minimum (0.45) was estimated at site 5 and site 9 in winter. The parametric index of diversity (Fisher’s index) was recorded its highest value at site 10 (11.89) in spring, while it recorded its lowest value (3.28) at site 1 in summer. The Shannon-Wiener diversity index ranged between 1.85 at site 9 in autumn and 3.71 at site 10 in spring. On the other hand, Simpson’s dominance index was ranged from 0.038 at site 10 in spring to 0.295 at site 9 in winter. The highest value of Simpson’s index of diversity (0.96) was recorded at site 10 in spring, while the less value was 0.71 at site 9 in winter. The highest value of Berger-Parker index (0.51) was recorded at site 9 in winter and the lowest (0.07) was recorded at site 10 in spring.
11- PERMANOVA revealed that the spatial variation was the most important factor that induced the variation in assemblages of algae (p=0.001), followed by the season that able to show the difference between algal species.
12- Water temperature, total alkalinity, nitrate and phosphate were the highest abiotic variables correlated with variation in algal composition.