Water Quality and Phytoplankton Communities in Lake Al-Asfar, Al-Hassa, Saudi Arabia
Some characteristics of Lake Al-Asfar, Al-Hassa, Saudi Arabia were monitored over a period of one year. Seasonal differences in the quantitative and qualitative composition of the phytoplankton communities in Lake Al-Asfar were marked. The maximum crop density was recorded in spring, whereas lowest values occurred in winter. The total crop densities were mainly a reflection of the trends in counts of Chlorophyceae. Four algal groups were recorded during the investigation: Bacillariophyceae, Chlorophyceae, Cyanophyceae and Euglenophyceae. Thirty nine species were identified allover the period of the investigation. Out of these, 14 species belong to Chlorophyceae, 15 belong to Bacillariophyceae, 7 to Cyanophyceae and 3 to Euglenophyceae. Chlorella sp., Chlorococcus humicola, Monoraphidium contortum, Oedogonium sp., Cyclotella meneghiniana, Gyrosigma sp., Fragilaria capucina, Navicula lanceolata, Surirella obonga, Synedra acus, Tabellaria sp. and Oscillatoria sp. were observed in a high rank of occurrence. Seven algal species were moderately common and 3 species were frequently recovered, most of them belong to Bacillariophyceae. The remaining recorded species were rarely recovered. Generally, the species data suggests that the water of Lake Al-Asfar can be considered as eutrophic.
Water chemistry exhibit variable physical and chemical characteristics and
consequently variable planktonic compositions (Fathi et
al., 2001; Fathi and Flower, 2005). These variations
depend mainly on the type and nature of the water area itself as well as on
the manmade additions or runoff of minerals and chemicals from agriculture soils
(Mohammed et al., 1986). Surveys of water chemistry
and algal vegetation at nine stream sites in the Asir Mountains, Saudi Arabia,
were made by Whitton et al. (1986).
Okla (1987) studied the algal micro facies in upper tuwaiq mountain limestone
(Upper Jurassic) near Riyadh, Saudi Arabia. Hussain et
al. (1996) surveyed a 16.5 km long irrigation canal in Al-Kharj City,
for its water chemistry and Charophyte periodicity and density. Al-Homaidan
and Arif (1998) studied the seasonal succession of bloom-forming algae over
a period of 3 consecutive years (1992-1995) in relation to the trophic changes
taking place in a semi-permanent rain-fed pool at Al-Kharj, Saudi Arabia. Shaikh
et al. (2004) studied the Phytoplankton ecology and production in
the Red Sea off Jeddah, Saudi Arabia. Recently, Al- Fredan
and Fathi (2007) studied the edaphic algae in Al-Hassa region.
Wetlands are very important natural areas. Millions of water birds depend on
them. Wetlands have on average the richest biodiversity of all ecosystems. By
using wetlands more effectively, recreational activities have become possible,
such as fishing, boating and bird watching. This has generated money from visitors
and provides sustainable development opportunities. The main reason wetlands
are so important is because they are important water provider. Nowadays wetlands
are capable of providing alternative sources of income for local communities
(Flower et al., 2001).
Arid environments are the most diverse ecosystems of Saudi Arabia. However,
much of their hydrobiology and its component biotic information are still unknown
to the scientific community (Al-Kahtani et al., 2007).
Al-Asfar Lake is one from the important shallow wetland lakes. It is located
on the eastern region of Saudi Arabia, Al-Hassa Province. However, much of their
limnology and its biotic information are still unknown to the scientific community.
Accordingly, this study will be conducted Al-Asfar Lake to report the results
on a routine sampling seasonally of water chemistry and algae over a one year
period, which it could be the first record.
MATERIALS AND METHODS
The Studied Area and Climate
Al-Asfar Lake is one from the important shallow wetland lakes. It is located
on Al-Hassa, eastern region of Saudi Arabia. Al-Hassa Province is one of the
largest oases in the world and located in the southern part of the eastern region
of Saudi Arabia. It is situated between 25° 05 and 25° 40 northern
latitude and 49° 55 eastern longitude. Al-Asfar Lake is located east of
the oasis of Al-Hassa, grow on the banks of many plant. The lake is the site
of the confluence of migratory birds from outside the area visited by dozens
of the virtues of birds. The lake formed a result of wastewater a farm in the
oasis of Al-Hassa.
Sampling Physico-Chemical Characteristics
A regular visit was monitoring the spring over a period of one-year (March
2007 to February 2008). Surface water samples were collected monthly
from different sites within the lake. The sites were distributed to give good
spatial representation of water quality. Temperature, pH, conductivity, total
dissolved salts and dissolved oxygen of the lake water were measured at each
location. pH was measured using a pH meter (370 pH meter Jenway, UK), conductivity
and total dissolved salts using a calibrated Conductivity Meter (470 Conductivity
meter, Jenway, UK). Dissolved oxygen was measured according to the Winkler method
(Strickland and Parsons, 1972). Total alkalinity, phosphate-P,
nitrate-N, chloride, silicate and major cations were measured in the lake water
samples according to Adams (1991). Sodium and potassium
concentrations were determined photometrically by flame emission according to
Golterman and Clymo (1971). The results were calculated
as mean values of triplicate measurements made on each water sample from each
of the four sampling stations.
Quantitative and Qualitative Analysis of Phytoplankton
Chlorophylls content of water was determined according to the method
described by Strickland and Parsons (1972). For phytoplankton
analysis, 1 L water samples were fixed in the field with acidified Lugol
s solution. In the laboratory samples were allowed to settle for at least 36
h, after which time the supernatant was carefully removed and the remaining
volume adjusted to a fixed volume. This sample was kept at 4°C until analysis.
Phytoplankton counts were done using a phase contrast Carl Zeiss (Jena Med2
microscope) at 100 and 40x magnification, following the Utermöhl technique
(Utermöhl, 1958). Diatoms were examined in permanent
preparations after cleaning in hydrogen peroxide to reveal frustules sculpture,
which is essential for species level identification. The permanent slides used
for diatom examination were prepared mainly according to Barber
and Haworth (1981).
For algal counting, the simplified methods described by Willen
and Hobro and Willen (1977)
Counts of phytoplanktonic algae (unicellular, colonial or filamentous) were expressed
as cells per liter. Cell numbers were calculated as mean values of triplicate
measurements at each of the four sampling stations. The algal taxa were identified
according to standard references, including Smith (1950)
, Bourrelly (1981)
and Fott (1983)
, Prescott (1987)
and Lange-Bertalot (1986
). Brillouin s index (H) as described by Pielou
was used for quantitative analysis of species diversity.
RESULTS AND DISCUSSION
It is well known that, the physical and chemical characteristics controlling
life in aquatic habitats, either saline or brackish water, lead to the appearance
of special types of biota (Fathi and Kobbia, 2000; Fathi
et al., 2001; El-Naghy et al., 2004;
Fathi and Flower, 2005; Al-Kahtani
et al., 2007).
The average water temperature of Lake Al-Asfar was subjected to seasonal variations.
The temperature of water reached its minimum in winter (16.8°C) while the
maximum (30.4°C) was recorded in summer (Table 1). The
water temperature of Al-Asfar Lake generally followed that of the air, due to
the shallow depth and large expanse of surface as compared with the volume (Ruttner,
1963). In the present investigation the lake did not show proper thermal
stratification, as it is extremely shallow (maximum depth 1.5 m). Allott
(1986) reported that thermal stratification is weak in the shallowest lakes.
Generally, it can be said that any increase or decrease in standing crop of
phytoplankton at Al-AsfarLake seemed to be strongly correlated with fluctuation
in water temperature. This is in accordance with results obtained by
Mohammed and Fathi (1990), Fathi and Kobbia (2000),
Fathi et al. (2001), Fathi
and Abdelzahar (2003) and Fathi and Flower (2005).
Change in pH value was always in the alkaline side. It fluctuated between 7.35
in winter and 8.12 in summer. Generally, this general tendency to the alkaline
side may be due to the increased photosynthetic activity of planktonic algae,
which was also previously recorded by El-Wakeel and Waihby
(1970), Kobbia et al. (1995), Fathi
and Kobbia (2000) Fathi et al. (2001) and
Fathi and Flower (2005). The lowest pH and alkalinity
values recorded in Al-Asfar lake may be due to greater amount of in flowing
agriculture water and also to the decomposition of plankton and organic matter
(Badawy et al., 1995; El-Nagar
et al., 1997, 1998; Fathi
and Abdelzahar, 2003).
The conductivity and the total dissolved salts (TDS) of water were found to
be higher in summer (11.93 mS cm-1 and 7.13 g L-1, respectively)
but dropped to a minimum level in winter (8.80 mS cm-1 and 5.32 g
L-1, respectively). The highest value of its electrical conductivity
and TDS could be attributed mainly to the high pollution levels in water, resulted
from the high nutrient loads of wastewater (Kobbia et
al., 1995; Fathi et al., 2001). On the
other hand Fathi et al. (2001) and Flower
et al. (2001) reported that the fluctuations of salinity of North
Egyptians lakes from time to time, could be explained by the differences of
the input amount of drainage water.
||Chemical composition of the Al-Asfar Lake water during the
|Means±SD (n = 3)
Dissolved oxygen is an important parameter for identification of different
water masses. The oxygen content of the investigated lake water tended to be
higher in summer (14.80 mg L-1) and lower in winter (5.29 mg L-1).
The relatively high concentrations of dissolved oxygen recorded in this study
(summer) could be mainly attributed to light intensity rather than photosynthetic
activity of phytoplankton. Mohammed and Fathi (1990),
Fathi et al. (2001) and Fathi
and Abdelzahar (2003) due to the increased photosynthetic activity of phytoplankton
populations. In this respect, Talling (1976) noticed that
oxygen super saturation due to photosynthetic activity is often encountered
in regions with abundant phytoplankton.
Total alkalinity of Al-Asfar Lake water reached its minimum in winter (117
mg L-1), whereas the maximum was recorded in spring (470 mg L-1),
this increases may be due to the bacterial decomposition of organic substrates
(Abdel-Satar and Elewa, 2001).
Monovalent and divalent cations play very important role in the productivity
of inland water. Calcium and magnesium are reported to be of importance for
phytoplankton production (Hussein, 1989). In the present
study the values of divalent (calcium and magnesium) and monovalent cations
(sodium and potassium) were relatively high at all samples, irrespective of
some minor fluctuations in seasonally readings. Levels of calcium and magnesium
were found to fluctuate within the ranges of 42.00-62.50 mg L-1 and
16.00-44.00 mg L-1, respectively. On the other hand the concentrations
of sodium were found to be higher throughout the study period, which exceeded
those of calcium, magnesium and potassium in the lake water. It fluctuated from
2.10 g L-1(in summer) to 1.25 g L-1 (in winter). Generally,
Al-Asfar Lake water showed rather higher values of sodium content. Despite its
major role in algal growth and photosynthesis, there are only a few instances
of either magnesium deficiency or toxicity in lakes (Goldman,
1960). Magnesium is usually present in aquatic system in large amounts relative
to plant needs. Both sodium and potassium play important role in the productivity
of water (Cole, 1983; Goldman and Horne,
1983). Talling and Talling (1965) suggested that
the amounts of sodium, calcium and chloride determine the species present rather
than quantitative development of phytoplankton.
Chloride attained their maximum in summer (2.16 g L-1) and dropped to their minimum in spring (1.60 g L-1). The high concentrations of chloride recorded in this study (summer) could be mainly attributed to drain water discharge or to high summer temperature which accelerate evaporations. It seemed probable that ions play significant role in biomass and standing crop, stated that chlorides appear to limit algal production directly in nature, but in the form of NaCl.
The maximum value of nitrate was found in winter 2.05 mg L-1 and
the minimum value in spring 1.02 mg L-1. The highest values of nitrate-N
reflect the direct effect of the agriculture runoff (Gharib
and Soliman, 1998), while the lowest values of nitrate-N are indicative
of phytoplankton uptake. On the other hand, phosphate content tended to be high
also in winter but lower in the other seasons. The recorded high phosphate values
probably due to the release of great amounts of adsorbed phosphate from the
bottom sediments or to drainage water (Gharib and Soliman,
1998). On the other hand the lowest values of phosphate concentrations could
be attributed to the vigorous uptake by the heavy blooms of phytoplankton (Mohammed
and Fathi, 1990; Fathi and Kobbia, 2000; Fathi
et al., 2001; Fathi and Flower, 2005). Silicate
levels fluctuated between the seasons without any regular trend. The observed
fluctuations in silicate concentrations were probably related to variation in
silicate uptake by diatom (Fathi and Kobbia, 2000).
The chemical oxygen demand was taken in the present study as a measure of the
oxygenated state and additionally the amount of organic \matter in water as
well. The data of this study show that COD tended to be higher in summer (44.00
mg L-1) and lowered on the other seasons. The increase in COD could
be attributed to the high organic matter content that produces about poor oxygenated
state of water (Fathi and Zaki, 1999; Fathi
and Kobbia, 2000; Aly and Yahya, 2002; Fathi
et al., 2001; Fathi and Abdelzahar, 2003).
On the other hand chlorophylls content in spring exceeded that recorded
in other samples (Fig. 1), which could be attributed to vigorous
phytoplankton growth (Fathi and Kobbia, 2000; Fathi
and Abdelzahar, 2003).
It is well known that, the changes in physico-chemical characteristics of any
water mass lead to concomitant qualitative and quantitative changes in phytoplanktonic
organisms (Mohammed et al., 1986). The data of
this study shows that there are marked seasonal differences in the quantitative
and qualitative composition of the phytoplankton communities in Al-Asfar (Table
2, Fig. 2). In terms of total cell number the maximum
count (163x106 cell L-1) was recorded in spring, whereas
the lowest densities occurred in winter (11x106 cell L-1).
The changes in total algal counts throughout the investigation coincided closely
with in Chlorophyceae abundance. It is worthy to mention that in summer sample
some blue green algal genera were recorded in a high abundance.
Four algal groups were recorded throughout the investigation period, Bacillariophyceae, Chlorophyceae, Cyanophyceae and Euglenophyceae (Table 2, Fig. 3). The total percentage composition of the four main phytoplankton groups shows that Chlorophyceae dominated the phytoplankton of Al-Asfar throughout the study period. Bacillariophyceae ranked second. Ranking third were the Cyanophyceae, which were least abundant in the summer. Euglenophyceae ranked fourth in order of dominance.
The data included in Table 2 further revealed that a total
of 39 species were identified allover the period of the investigation. Out of
these, 14 species belong to Chlorophyceae, 15 belong to Bacillariophyceae, 7
to Cyanophceae and 3 to Euglenophyceae.
||A seasonal variation of chlorophylls content in Al-Asfar
Lake during the investigation period
||The percentage composition of the main algal groups recorded
at Al-Asfar Lake during the investigation period
||Relative occurrence of the phytoplankton on Al-Asfar Lake
during the study period
|High: ++++, Moderate: +++, Frequent: ++, Rare: +
||Phytoplankton abundance (No. x105 L-1)
for Al-Asfar Lake during the investigation period
||Seasonal variations of the species richness (total number
of phytoplankton taxa encounted per standard sample count of Al-Asfar Lake
phytoplankton, during the investigation period
The maximum number of phytoplankton taxa (species richness) on any one sampling
period (35 species) occurred in spring, while the minimum (17 species) was in
winter (Fig. 4). Chlorella sp., Chlorococcus humicola
Monoraphidium contortum, Oedogonium sp., Cyclotella meneghiniana,
Gyrosigma sp., Fragilaria capucina, Navicula lanceolata,
Surirella obonga, Synedra acus, Tabellaria sp. and Oscillatoria
sp. were observed in a high rank of occurrence. Seven algal species were
moderately common such as (Ankistrodesmus fusiformis, Cymbella cistula,
Nitzschia sp. Synedra ulna, Phormidium sp. and Euglen
prmoxia and Euglena acus). On the other hand 3 species were frequently
recovered, most of them belong to Bacillariophyceae. The remaining recorded
species were rarely recovered. Generally, the phytoplankton crop showed a remarkable
increase indicted high level of eutrophication in Lake Sector.
The data of Table 2 also shows that the maximum diversity
index 2.08 was estimated on summer, while the minimum 0.66 was in winter. It
should be noted that biological indices of species diversity, based mainly on
the composition of phytoplankton have been proposed by Pielou
(1966) and Nygaard (1978) may indicate the pollutional
state of water. There are several numerical attempts (Sabae
and Rabeh, 2000) to express degrees of oligotrophy and eutrophy from a consideration
of species complements rather than from nutrient levels (Shaaban
et al., 1985). Nosseir and Abou El-Kheir (1970),
Fathi and Zaki (1999), Fathi et
al. (2001) and Fathi and Flower (2005) believe
that the biological estimation of the degree of eutrophication and pollution
of aquatic ecosystems is probably more informative than chemical determinations.
According to the phytoplankton one could consider that the water of Al-Asfar
are eutrophic. According to scales of Staub et al.
(1970), Al-Asfar is indicates heavy polluted in autumn and winter and moderate
pollution in spring and summer. In conclusion, the investigated lake area is
contaminated with discharge waters enriched with chemicals fertilizers in addition
to domestic and industrial effluents. These are manifested by high amounts of
organic matter, a high concentration of nutrients (causing eutrophication).
We thank Prof. Abdalaziz. A. Almulhem the Dean of Deanship of Scientific Research, King Faisal University and the Deanship members for financial support (Grant No: 8060).
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