Journal of Applied Sciences Research, 5(12): 2083-2095, 2009
© 2009, INSInet Publication
Assessment of Nile Water Quality via Phytoplankton Changes and Toxicity Bioassay Test
1
Shehata, S.A., 1 Badr, S.A., 1 Ali, G.H., 1 Ghazy, M.M., 2Moawad, A.K. and 1Wahba, S.Z.
1
Water Pollution Research Department, National Research Centre, Cairo, Egypt
2
Faculty of Engineering, Al Azhar University, Egypt.
Abstract: Changes of phytoplankton density along the river Nile have been monitored at Cairo district
between July 2007 and June 2008. River Nile water contains algal species belonging to three major
phytoplankton groups, namely; Chlorophyta (green algae), Cyanophyta (blue-green algae) and
Bacillariophyta (diatoms). A total of 90 taxa have identified during the study period July 2007 to June
2008. Out of which 38 taxa belonging to Chlorophyta, 36 taxa of Bacillariophyta and 16 of Cyanophyta.
Phytoplankton seasonal succession was dominated by diatoms. High species diversity was detected in
green algae group (0.64-1.19) followed by diatoms (0.41-1.0) then blue-green algae (0.34-0.73). The
diversity of the three algal groups indicated that the river Nile water is oligotrophic. These results
confirmed by those results obtained from toxicity bioassay using Daphnia magna. The density of total
phytoplankton numbers fluctuated between 10 6 – 10 7 Organism/ml. The Concentration of chlorophyll "a"
was ranged from 11.7 – 52.7 µg/L. Significant correlation was established between total algal counts and
chlorophyll "a" content.
Key words: River Nile W ater, Phytoplankton, Algal Count, Chlorophyll "a", Diversity, Redundancy,
Toxicity Bioassay Test, Daphnia magna.
INTRODUCTION
The Nile system consists principally of three main
streams; the W hite Nile and Blue Nile rivers, whose
combined waters flow for 3080 Km as the main Nile
from Khartoum (Sudan) to the Mediterranean Sea. The
creation of Lake Naser has had a markedly effect on
the river downstream by regulating flows and by
modifying the biological characteristics of water. River
Nile is considered to be the life line of Egypt. After
High Dam construction, water of river Nile is held
enough to permit significant changes in phytoplankton
population [1 ,2 ,3 ,4 ].
Human activity has altered the landscape over
centuries, resulting in substantial loss of habitat and
aquatic diversity [5 ]. Broad-scale environmental pressures
such as agriculture, point and non-point source of
pollution, climate change and land-use change overlap
in space and time, requiring that stress measures
incorporate assessment of cumulative impacts across
multiple stressors [6 ,7 ,8 ] . Biological assemblages are
important sentinels of environmental conditions, since
they are more sensitive to the combined effect of
stressors than to a single stressor [9 ,1 0 ]. Therefore, they
integrate cumulative impact that would not be detected
in another way or that would be other wise
underestimated (e.g., habitat degradation, highly
Corresponding Author:
variable pollution levels due to point and non-point
pollution).
W orldwide aquatic ecosystem has been impacted
by the excessive release of pollutants, leading to
phytoplankton blooms and to the disruption of the
structure and functioning of these systems [1 1 ,1 2 ,1 3 ]. The
growing need to analyze the present state of ecosystem
and monitor and predict their rate of change has
triggered a demand for studies that explore species
environment relationships and use these relationships
for assessing a nd p red icting changes under
anthropogenic influence [1 4 ,1 5 ,1 6 ]. The development of
indicator systems based on species environment
relationships has became a widely used approach for
these tasks [6 ,1 4 ]. Building on this, long tradition of using
organisms in monitoring and assessment programs. The
European Commission issued a directive mandating the
use of different organism groups to monitor the
integrity of inland waters and coastal regions. The
W ater Framework Directive (W FD- 2000/60/EC)
requires the use of different organism groups such as
fish, invertebrates, macrophyts and phytoplankton,
either singly or together, in assessing the ecological
status of aquatic ecosystems.
Chemical substances which affect the quality of
water are numerous, act in a great range of
concentration and vary continuously and erratically in
Salwa A. Shehata, Water Pollution Research Department, National Research Centre, Cairo,
Egypt.
E-mail: s_a_shehata@yahoo.com
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J. App. Sci. Res., 5(12): 2083-2095, 2009
concentration. The attempt to establish criteria in terms
of chemicals toxicity to aquatic organisms may exceed
the capability of adequate testing due to the large
number of toxic compounds, the vast numbers of biotic
species, the effects of interaction among compounds
and the wide range of effect produced by variations in
physical and chemical condition [1 7 ].
Therefore, the main objectives of the present
investigation are:
1. To assess the water quality of the river Nile using
phytoplanktonic community structure changes.
2. To evaluate the alternation in algal diversities and
relative proportion of the nuisance algae.
3. To assess the safety of Nile water quality via
toxicity bioassay test using Daphnia magna.
M ATERIAL AND M ETHODS
Sampling Site: Subsurface water samples were
collected from the main sources of drinking water in
Egypt (River Nile). W ater samples were collected at
monthly intervals for one year (July 2007-June 2008).
Study area of the river Nile is located in Helwan and
Cairo districts along @ 45 Km. Six sampling sites
were chosen (Fig. 1) as follows:
H1=
C 1=
H2=
C 2=
H3=
C 3=
3- Diversity and Redundancy: Two community
composition parameters namely diversity (H`) and
redundancy index (R) were estimated according to
W ashington’s equation [2 2 ].
Diversity was estimated using the following
equation
H` = -
W here: S: number of taxa samples
ni : number of individuals.
N: Samples size
In addition redundancy (or dominancy) index (R)
was estimated for each group using the following
equation:
R =
where: H` (max/S) and (min/S) are maximum and
minimum values of H` at given S.
Toxicity Bioassay Test: Toxicity assessments were
performed using acute toxicity tests for 48 hrs. of Nile
water at the sampling sites on the water flea, Daphnia
magna in optimal and standardized conditions in
laboratory.
El-shobak
intake of El-Fostat water works
infront of Iron and Steel Factory
intake of El-Giza water works
intake of Kafer El-Elow water works
intake of Rod El-Farag water works
P hy t o p la nkto n P a r a m e ter s : E n um e ra tio n o f
phytoplankton, quantification of chlorophyll “a”
concentration and phytoplankton productivity were
accomplished according to Standard Methods [1 8 ].
2.1- Phytoplankton Enumeration and Taxonomic
Identification: The phytoplankton present in the Nile
water samples were concentrated by means of
Sedgwick-Rafter [1 9 ]. Nile water algae were identified up
to the species level according to the key of freshwater
algae [2 0 ,2 1 ]. The number of phytoplanktonic organisms
present in the sample was calculated according to
Standard Methods [1 8 ].
2.2- Chlorophyll Content: A spectrophotometric
measurement of absorbance and optical density at three
different wave lengths was the method adapted for
estimation of chlorophyll extracted via organic solvents
according to Standard Methods [1 8 ]. The clear extract
was transferred to a 1-Cm cuvette and absorbencies
were determined via a UV-VIS Recording Shimadzu
Spectrophotometer Model (UV-2401 PC).
Culture: Daphnia magna (Crustacea, Cladocera) used
in the experiments originated from stocks maintained
for several years in the laboratory in a synthetic
freshwater medium [2 3 ]. This medium is characterized by
pH 7.9, conductivity 260 µmhos, alkalinity 34 mg/L (as
CaCO 3 ) and total hardness 90 mg/l (as CaCO 3 ).
The animals were cultured and undergone toxicity
at 22±2 o C on a 16:8 hrs. light: dark photoperiod. They
were fed with unicellular green alga namely;
Scenedesmus obliquus three times a week for rearing.
The alga was grown in the culturing medium
recommended by APHA [1 8 ].
Short Term (48h Acute) Test: Forty-eight hour acute
(static system) toxicity tests were conducted with less
than 24hr old D aphnids. Each of the tests was
replicated three times and started with 10 Daphnids in
100 ml of the holding medium introduced in 250- ml
glass beaker. Mortality was recorded at 48h. Death was
defined as the lack of mobility in response to prodding
with a probe during a 5 seconds observation period.
Toxicity tests were run without food addition as
recommended by the standard toxicity testing [1 8 ].
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J. App. Sci. Res., 5(12): 2083-2095, 2009
1 & Fig. 2). On the other hand, these algal species
number represents 42.2%, 40% and 17.8% of total
algal species number respectively.
C om m on and Significant
River N ile.
Algae Taxa
C hlorophyta (G reen A lgae)
Actinastrum hantzschii
Ankistrodesm us acicularis
Ankistrodesm us falcatus
Botryococcus braunii
Chlam ydomonus variabills
Closterium pronum
Chodatella cillata
Coelosterum m icroporum
Crucigenia rectangularis
Cosmarium bioculatum
Table 1:
Species of A lgae along the
Algae Taxa
Selenastrum gracile
Spirogyria m irabits
Sphaerocystis schroeteri
Staurastrum paradoxum
Tetraedron minim um
Tetraedron muticum
U lothrix subitllssim a
C y a n o p h y ta (B lu e-G reen
A lgae)
Anabaena flos-aqua
D ictyosphaerium pulchellum
G olenkinia radiata
Chrococcus turgids
Chrococcus lim neticus
Coelosphaerium kuetzingianum
Cylindrosperm um stagnale
Kirchneriella lunaris
D actylocoleobsis rhaphidioides
M icracitinum pusillum
M ougeotia scalaris
G om phaspheria aponina
G om phaspheria naegeiiania
Nephrocytium lum atum
O ocystis lacustris
O ocystis parva
O ocystis solitaria
Pediastrum boryanum
Pediastrum clathratum
Pediastrum duplex
Pediastrum sim plex
Pediastrum tetras
Pediastrum gracillium
Lyngbya martonsiane
M erismopedia elegans
M icrocystis aeruginosa
M icrocystis flos-aqua
O scillatoria chlorina
O scillatoria lim entica
O scillatoria lim osa
Eudorina elegans
Fig. 1: Location map of the river Nile showing
Sampling sites.
Scenedesm us acum inatus
Scenedesm us obliquus
Scenedesm us platydiscus
Scenedesmus quadricauda
Calonies am phisbaena
Ceratium hirundinella
Cocconies placentula
Cyclotella comta
Cyclotella glom erata
Cyclotella antigna
Cym atopleura solea
Cym bella trugida
D iatom a elongatum
RESULTS AND DISCUSSION
C o m p o s it io n a n d S e a s o n a l S u c c e s s i o n o f
Phytoplankton: Phytoplankton composition of the
River Nile contained algal species belonging to three
algal groups, namely; Chlorophyta (green algae),
Cyanophyta (blue-green algae) and Bacillariophyta
(diatoms). A total of 90 algal species were recorded,
out of which 38 taxa belonging to Chlorophyta, 36 taxa
of Bacillariophyta and 16 species of Cyanophyta (Table
Spirulina abbreviate
Bacillariophyta (D iatom s)
Achnanthes lanceolata
Am phora coffeaeform is
Asterionella gracillim a
Navicula
Navicula
Navicula
Navicula
Navicula
cuspidata
exigua
bacillum
gastrum
cryptoccephala
Nitzschia
Nitzschia
Nitzschia
Nitzschia
Nitzschia
acicularis
filiform s
holostica
linearis
paradoxa
Epithem ia sorex
Fragilaria capucina
Fragilaria construens
G om phonema olivaceum
G yrosigm a scalproides
G yrosigm a attenuatum
G yrosigm a kutzingii
M elosira granulata
2085
peridinium cinctum
pinnularia borealis
pleurosigm a delicatulum
Stauraneis phoeniotroa
Stephanodiscus dubius
Surirella ovalis
Synedra ulna
J. App. Sci. Res., 5(12): 2083-2095, 2009
Fig. 2: Seasonal change in phytoplanktonic species number along the river nile.
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Diatoms were the most dominant and diversified
group present in good numbers during four seasons
especially in fall and winter seasons followed by green
algae. Blue-green algae were presented in small number
during different seasons (Fig. 3). Among the diatoms,
Cyclotella comta was the most dominant throughout the
year, other important centric diatoms was Melosira
granulata. Pinnate diatoms were dominated by Diatoma
elongatum and Synedra ulna. In general terms, the
diatoms found are characteristic of eutrophic water
bodies and most are recorded as halophytic which
preferring alkaline waters [2 4 ], which correspond to the
conditions of relative high pH in the river Nile.
The green algae were dominated by small
planktonic Chlorococcales belonging to the genera;
Scenedesmus, Ankistrodesmus, Botroyococcus and
Dictyoshaerium. Cyanophyta rarely grew to significant
concentration except during periods of high temperature
in spring and summer seasons (Fig. 4). The numbers of
genera or species of Nile water algae that are
responsible for causing serious problems in water
works are relatively high. Some genera of diatoms are
significant in this respect and certain green algae and
blue-green algae are also important (Table 2).
M axim um V alues of N uisance Algae m ost Frequently
recorded in the River N ile W ater D uring the Study Period
Algal species
M axim um value (O rg./m l )
Green Algae
Ankistrodesmus spp.
521
Scenedesm us spp.
309
U lothrix subitllssim a
273
D ictyospharum pulchellum
198
Blue-green A lgae
M erismopedia elegans
322
M icrocystis flos-aqua
339
O scillatora lim netica
339
Coelosphaerium kuetzingianum
166
D iatom s
Cyclotella spp.
11220
M elosira granulata
2429
D iatom a elongatum
1785
Stephanodiscus dubius
1562
Synedra ulna
1562
Nitzschia spp.
245
Table 2:
Konno [2 5 ] observed that slender type diatoms
Nitzschia and Synedra causing filter clogging in rapid
sand filtration systems and the settling velocity is
related to the physiological conditions of the algae.
C y a n o p h yta o fte n d o m in a te th e fre s h -w a te r
phytoplankton community in surface waters, particularly
in eutrophic system and are major producers of toxins
as well as taste and odor compounds [2 6 ].
Changes in Phytoplankton Density: Clear variability
was found in total algal numbers during different
investigated seasons (Fig. 3). The algal counts ranged
from 2246 to 21245 Org./ml with maximum attained
during fall and winter seasons dominated with species
belonging to diatoms which favorite low temperature.
O ¢ Farrell [2 7 ] studied the phytoplankton community
structure and dynamics of Salado River during 18
months (1987-1989). He found that, the abundance
ranged from 2722 Org./ml (1988) to 498094 Org./ml
(1989).
The increase in total phytoplankton number in Nile
water mainly attributed to diatoms which represents
75% - 97.8% of total algal counts and dominated by
centric form and secondarily by pinnate form (Figs. 57). Green algae restricted their growth to the spring
season and comprise about 20% of total algal counts.
Fortunately, blue-green algae rarely grew to significant
numbers during the investigated period. Blue-green
algae had its maximum density in summer season with
8% of total algal counts (Fig. 5).
Generally, the presence of high proportion of
diatoms in Nile water algae (Figs. 6&7) indicated that,
water works will expect to expose frequent taste and
odor problems and reduction in filter runs (Table 2).
Changes in Species Diversity and Redundancy: The
structure of phytoplankton community can be
summarized clearly and briefly in diversity and
redundancy index derived from information theory.
Values less than 1.0 have been obtained in heavy
polluted areas, while values from 1 to 3 in moderate
polluted areas and values exceeding 3 obtained in clean
areas.
Therefore, changes in species diversity and
redundancy can be used as an indicator of changes in
water quality. During study period Nile water was
characterized by high species diversity in green algae
(0.64-1.2) followed by diatoms (0.41-1.0), then bluegreen algae (0.34-0.73) Table (3). Monthly diversity
value of blue-green algae remained almost constant and
varied between (0.34-0.73). However, the low diversity
associated with high redundancy (1.0) due to the
dominance of Merismopedia elegans (Table 4).
Accordingly, throughout the study period the
diversity of the three algal groups indicted that the
River Nile waters at different study sites are
oligotrophic [2 8 ]. Stvenson and W hite [2 9 ] recorded that,
phytoplankton diversity changed with water quality,
decreasing with nutrient enrichment and increasing with
conditions that probably changed.
Chlorophyll "a" Content: The concentration of
chlorophyll "a" ranged from 11.7 to 52.7 mg/l (Fig. 8).
The high value was detected during winter season at
site C 2 due to the abundance of diatoms species.
However good relationship between phytoplankton and
chlorophyll "a" content were established indicating that
physiological state of River Nile phytoplanktonic algae
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J. App. Sci. Res., 5(12): 2083-2095, 2009
Fig. 3: Distribution pattern of algal groups along the river nile during different seasons.
Fig. 4: Dominant and Significant Algal Species of River Nile During Years (2007-2008).
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Fig. 5: Percentage of various algal groups from total algal counts during different seasons.
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Fig. 6: Monthly changes in pinnate and centric forms of diatoms at helwan district.
Fig. 7: Monthly changes in pinnate and centric forms of diatoms at cairo district.
2090
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Fig. 8: Relationship between total algal count and chlorophyll ‘a’ content.
Fig. 9: Evaluation the effect of raw nile water at different sites using daphnia magna
is in good condition. Similar results was obtained by
Shehata et al.[3 ] who found that, chlorophyll "a" content
ranged from 4.2-34.2 mg/l for River Nile water. In
winter season biomass achieved its maximum due to
the abundance of diatoms species. In addition, good
co rrelation between phytoplankton counts and
chlorophyll "a" contents.
Also, Shehata et al.[4 ] found that chlorophyll "a"
concentration ranged between 11.8-37.2 mg/l. However,
the highest value of chlorophyll "a" was found at
December 2000 for River Nile water. This is due to
the presence of high count of filamentous forms of
diatoms namely; Melosira spp. which contain high
chlorophyll "a" content. Havens [3 0 ] recorded that, the
maximum chlorophyll "a" concentration was more 40
mg/l at eutrophic Lake at Florida. In addition, he found
a good relation between chlorophyll "a" concentration
and algal bloom frequencies.
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J. App. Sci. Res., 5(12): 2083-2095, 2009
Table 3: Changes in D iversity (H \ ) at D ifferent Sites of River N ile
G reen A lgal
Sites
---------------------Seasons
H1
H2
H3
C1
C2
C3
Sum m er 2007
1.00
1.00
0.96
1.00
1.00
1.07
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------Full
2007
1.09
1.00
0.78
0.90
0.97
0.96
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------W inter
2008
0.92
0.91
0.73
0.64
0.93
0.74
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------Spring
2008
1.19
1.18
0.90
0.99
1.07
1.00
Blue-green A lgae
Sites
---------------------Seasons
H1
H2
H3
C1
C2
C3
Sum m er
2007
0.63
0.56
0.58
0.54
0.60
0.58
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------Full
2007
0.57
0.55
0.56
0.46
0.46
0.53
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------W inter
2008
0.56
0.49
0.34
0.46
0.59
0.46
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------Spring
2008
0.73
0.72
0.62
0.54
0.68
0.60
D iatom s
Sites
-------------------Seasons
H1
H2
H3
C1
C2
C3
Sum m er 2007
0.67
0.68
0.61
0.59
0.65
0.63
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------Full
2007
0.62
0.64
0.59
0.61
0.66
0.68
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------W inter
2008
0.46
0.58
0.46
0.49
0.50
0.41
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------Spring
2008
1.00
0.69
0.62
0.68
0.82
0.69
Total A lgae
Sites
---------------------Seasons
H1
H2
H3
C1
C2
C3
Sum m er
2007
0.96
1.00
0.86
0.82
0.88
0.93
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------Full
2007
0.76
0.74
0.74
0.66
0.84
0.88
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------W inter
2008
1.01
0.71
0.60
0.69
0.69
0.65
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------Spring
2008
1.07
1.05
0.94
1.00
0.95
0.98
Table 4: Changes in R edundancy ® at D ifferent Sites of River N ile.
G reen A lgal
Sites
--------------------Seasons
H1
H2
H3
C1
C2
C3
Sum m er 2007
0.39
0.63
0.0
0.0
0.51
0.0
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------Full
2007
0.70
0.77
0.80
0.30
0.77
0.32
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------W inter 2008
1.0
1.0
1.0
1.0
1.0
1.0
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------Spring 2008
0.0
0.0
0.27
0.05
0.0
0.23
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Table 4: C ontinue
Blue-green A lgae
Sites
--------------------Seasons
H1
H2
H3
C1
C2
C3
Sum m er
2007
0.60
0.66
0.13
0.04
0.36
0.16
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------Full
2007
0.95
0.72
0.70
0.97
1.0
0.49
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------W inter
2008
1.0
1.0
1.0
1.0
0.40
1.0
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------Spring
2008
0.0
0.0
0.0
0.0
0.0
0.0
D iatom s
Sites
----------------------Seasons
H1
H2
H3
C1
C2
C3
Sum m er
2007
0.64
0.08
0.09
0.48
0.54
0.16
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------Full
2007
0.74
0.47
0.14
0.36
0.48
0.30
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------W inter
2008
1.0
1.0
1.0
1.0
1.0
1.0
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------Spring
2008
0.0
0.0
0.0
0.0
0.0
0.0
Toxicity Bioassay Test: Acute toxicity tests with
aquatic invertebrates such as those based on mortality
of the water flea, Daphnia magna are reliable and
sensitive tests to monitor contaminant trends in water
quality and to determine toxicity of complex effluents
discharged into aquatic systems. Fig. (9) indicated that
River Nile waters are oligotrophic, except site (H 3 )
down stream of industrial area in June 2008. The water
collected from this site cause acute toxicity to the test
organism, Daphnia magna where 57 % mortality was
recorded. This may be due to the discharge of toxic
industrial waste or accidental effect from oil pollution.
However, next month the water recovered and the
mortality rate decreased to reach 13%. This indicated
that the River Nile has ability to recover from
pollutants by self-purification.
Gustavson et al. [1 7 ] recorded that bioassays have
been extensively used to document toxicity of surface
water and evaluate the potential toxicity of waste
discharges into these waters.
Conclusion: The total algal counts of the River Nile
has considerably changed during different seasons and
increased one tenfold at winter season.
Enumeration of algae in surface water samples is often
a necessary part of water quality monitoring and algal
research.
Algal counts are more reliable to predict the type
of drinking water treatment steps for overcoming the
planktonic algae.
R e c o m m e n d a tio ns: R egular m o n ito r in g o f
phytoplankton populations in drinking water sources as
well as toxicity bioassay test are necessary to
understanding the development of phytoplankton
community structure and the status of Nile water
quality. Also, to select water treatment schemes for
overcoming Nile water algae.
ACKNOW LEDGM ENT
This study was carried out within framework of
the project entitled "Algal Removal from Drinking
W ater Sources" with collaboration between Holding
Company for Water & W astewater and National
Research Center. This project has been funded by the
Holding Company for W ater and W astewater. Also, the
authors are deeply indebted to Prof. Abd-El Kawi
Khalifa, Charmin of Holding Company for Water and
W astewater for sponsoring this research work.
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