الفهرس 
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Abstract
The present study aimed to investigate temporal and spatial variations in physical and chemical parameters as well as changes in phytoplankton composition in Ismailia canal water. A total of 144 Water and phytoplankton samples were collected monthly from twelve different sites along the main route of Ismailia canal during the period between February 2015 until January 2016. The sites of sampling were chosen to be near to or at the input of some represintitive drinking- water treatment plants supplied from the canal water. Physical and chemical parameters of water have been detected for each sampling station in order to study the relationships between physicochemical factors and phytoplankton communities using multivariate statistical approaches.
Physico-chemical analysis of Ismailia canal water showed that pH values detected were ranging between neutral to alkaline. The alkalinity of the canal was mainly due to high levels of bicarbonate ions measured, while no considerable concentrations of carbonate ions was detected. The turbidity
of the canal showing to be related to chlorophyll a content and both obey a seasonal variation increasing in autumn and decreasing in summer. Canal water turbidity values in most sampling stations showed no remarkable variations except at station 12 which recorded the lowest average turbidity value. The average dissolved oxygen values elevated in winter and spring due to increase in photosynthetic activities, while decrease to the lowest values in summer. As a freshwater resource, the salinity of Ismailia canal was very low and show a little raise at the end of the canal due to mixing with suez canal water.
Nutrients analyses of the canal indicating changing of ammonium, nitrate, nitrite, phosphate, and silicate concentrations with changes in water-flow from Aswan High Dam. The nutrient concentrtions show a a pattern of gradual increase through the drought period in autumn and winter, then gradually decrease through flooding period in spring and summer and another peak of remarkable increase at the end of the flooding period in late summer due to increasing in agricultural activities and agricultural runoff into the canal.
The analysis of monthly variations in phytoplankton densities of Ismailia canal reavealed that average phytoplankton counts show a similar pattern that follow the pattern of changes in nutrient concentrations dependent on water-flow changes, with highest counts were recorded in winter and spring, while lowest average counts were recorded in summer. The diversity of phytoplankton taxa was highest in spring and lowest in winter.
The total phytoplankton taxa recorded in Ismailia canal were 143 taxa depending on the available literatures. These taxa belong to 55 algal genera and six algal divisions which are: Chlorophyta (69 taxa), Bacillariophyta (51 taxa), Cyanophyta (18 taxa), Euglenophyta (2 taxa), Dinophyta (2 taxa) and Xanthophyta (1 taxon). The most dominant division at all stations in all months was Bacillariophyta with average ratio 86.3% of total algal count, followed by Chlorophyta with average ratio 7.6% of total algal count, then Cyanophyta with average ratio 5.9% of total algal count.
Bacillariophyta reached its maximum counts in January representing 98% of total algal density and reached its minimum density in July by 62% of total algal density. The
most dominant taxa of Bacillariophyta was Synedra ulna var. danica, Cyclotella ocellata, Fragillaria constreuns, Aulacoseira granulata, and A. granulata var. angustissima.
Both Chlorophyta and Cyanophyta flourish in spring and summer, reaching the highest average ratio of total count in July by 21% and 17% respectively, and recorded the lowest average ratio in January by only 1% for each division.
The most dominant taxa among chlorophyta was Pediastrum simplex var. duodenarium, Staurastrum paradoxum, Actinastrum gracilimum, Dictyosphaerium pulchellum, and Ankistrodesmus flacatus. Concerning to Cyanophyta, Merismopedia tenuissima, Microcystis aeruginosa, and chroococcus minutus was the most dominant taxa.
The average values of water quality index Qr that calculated based on the phytoplankton functional groups detected in the canal were in the good range in all months except in July when it decreased into the medium range, and also show a good range of quality in all stations except in last station as it decreased to medium quality.
The CCA triplot diagram reveal the relationships between chemical and physical factors with each other and with both the distribution of phytoplankton representative taxa and sampling months. It can be revealed that temperature, alkalinity, silicate and nitrate concentrations were the most effective factors that control phytoplankton distribution. It also shows a simultaneous relationship between chlorophyll a, dissolved oxygen and turbidity and all show an inverse relation with temperature.
The increaseing in Bacillariophytes Synedra ulna var. danica and Cyclotella ocellata in January and December in all stations was attributed to the low temperature and low water level due to drought period.
Increasing in biomass of Peridinium cinctum and Euglena gracilis at station 12 during October (during drought period) and August (at the end of flooding period) indicating a highly eutrophic shallow water and revealing that this part at the end of the canal is very sensitive as it contains shallow water with nearly no current and therefore acts as sink of pollutants.
Finally, it’s concluded that the canal water is receiving agricultural and industrial run-off. Changes in water-flow rates by High-Dam periodically was found to affect the ability of the canal water to renew itself, especially at the far eastern end of the canal which has shallow water with nearly no current and therefore low ability to renew. This cause the water quality at this point of the canal changes dramatically during drought period. Therefore, it’s recommended that continuous studies must be carried out to follow up the changes in water quality of the canal.