Interestingly Ananthapura is the only lake temple in Kasargod district of
Kerala state, though surrounded by barren land all around. It is truely amazing
to see a lake and Ananthapura temple in the middle, which is said to be the
Moolasthanam (Shrine) of the Ananthapadmanabha Swami (Sri Padmanabha
Swami Temple) of Thiruvananthapuram (Head of Kerala). Local tradition has it
that Ananthapadmanabha of Thiruvananthapuram had settled down here originally.
During the monsoon season, from the barren land water come to the lake and water
volume had increased up to the door level of the temple. The lake water is used
for irrigation, domestic and temple purpose. The waste material of after pooja,
which contains milk, ghee, ash, turmeric water, curd, prasadam and naivedyam
of crocodile food, these were the only polluting material comes from temple
to lake. Virtually all the dynamic features of lakes such as colour, clarity,
trophic state, zooplankton and fish production depend to a large degree on the
phytoplankton (Goldman and Horne, 1983). The growth of
phytoplankton is regulated by various physical and chemical factors (Komarkova
and Hejzlar, 1996; Naselli-Flores and Barone, 2000).
The phytoplankton investigation by Kotut et al.
(1998) revealed that the seasonal changes in phytoplankton biomass, diversity,
composition and primary production were mainly influenced by seasonal changes.
Diversity of freshwater planktons are based on the fact that interactions in
the planktonic environment are highly complex. Ecologists have designed a large
range of indices and models for measuring diversity and yet diversity is so
hard to define (Maguran, 1983). This is because diversity
consist of two components, firstly the variety and second the relative abundance
of species. Diversity measures are more useful tool in aquatic ecosystem, which
measure a large variety of algal species in general and species diversity within
the genera. Generally, seasonal variations in the dynamics of the composition
and productivity of phytoplankton population have been shown to depend largely
on nutrient concentrations, on the degree of mixing due to turbulence and interactions
in food webs (Rhew et al., 1999). In large shallow
lakes and ponds, physical and chemical factors, mainly wind-driven sediment
resuspension and eutrophication levels, are considered more important to influence
phytoplankton population (Wu et al., 2007).
It was recognized early on that phytoplankton composition change with increasing
levels of nutrients. Unfortunately no data available on the physicochemical
and biological conditions of the Ananthapura temple lake, which led us to design
the present study. This study was designed to examine some of the seasonal influences
of water quality on phytoplankton and to give base-line conditions for assessment
of future change and algal biodiversity in the lake. Results of routine monthly
sampling of water chemistry and phytoplankton over seven months are reported.
MATERIALS AND METHODS
Monthly samplings were carried out in Temple lake of Ananthapura, Kerala
(Fig. 1) from January-July 2010. The pond size is 42x27x3.5
m length, width and depth, respectively. Pond was received direct sunlight.
The procedure for collection, storage and analysis of water samples were followed
as described in standard methods (APHA, 1998).
Different sites of pond were visited monthly for a period of (January-July
2010) seven months to study the various ecological parameters such as water
temperature, Rain fall, pH, dissolved oxygen, biological oxygen demand, chemical
oxygen demand, free carbon dioxide, total alkalinity, total dissolved solids,
chloride, silicate, nitrate and phosphate. Collections were made using plastic
containers of 2 L capacity. The plastic containers rinsed thoroughly with sampling
water before using them. After filling the containers they were sealed and transferred
to the laboratory for the estimation of various physicochemical parameters by
following standard methods (APHA, 1998).
Water temperature of the lake was recorded on the spot with an ordinary glass
mercury thermometer calibrated to tens of a degree centigrade. The hydrogen
ion concentration (pH) was measured using pH meter (Elico 120 I). Water samples
were taken carefully into 300 mL BOD bottles avoiding air bubbles. The samples
collected were fixed separately by using Winklers method in the field
itself for estimation of dissolved oxygen, further estimation was carried out
in laboratory with winklers modified method and the result has been expressed
in mg L-1 (Viessman and Hammer, 2000).
Carbon dioxide (CO2) was estimated by titrating samples against
sodium hydroxide using phenolphthalein as an indicator. Total alkalinity of
the samples was estimated by titrating against sulphuric acid using phenolphthalein
and methyl orange as indicators to establish the end point. Total dissolved
solids of the water samples were estimated by evaporation method and expressed
in mg L-1. Phosphate (PO4-P) and silicate were measured
by APHA (1998).
The phytoplankton samples were collected from the sites using plankton silk
net cloth and were fixed with Lugols iodine solution. Phytoplankton samples
were also fixed in 4% formaldehyde solution for proper identification in the
|Fig. 1: Map of the Temple Lake Ananthapura
Identification of various taxa was done by using the taxonomic keys given in
Prescott (1973), Desikachary (1959),
Philipose (1967) and John et al.
(2002). Identification and enumeration were done by a binocular microscope
(Nikon Eclipse E 200) and the frequency of phytoplankton species was determined
by heamocytometer, based on the percent occurrence of an individual species.
The algae were expressed as organisms per ml for the purpose of calculating
diversity indices. The data were subjected to a software program PAST (Hammer
et al., 2001) which generates nine diversity indices. The formula
designed for various index are described below. Dominance index = 1-J, J is
evenness of relative diversity (H/Hmax) where absolute evenness
= 1.00. The Shannon Weiner index (H) assumes all species are represented,
sample randomized = Σpi in pi; pi = proportion of the ith species
and natural logarithm. The Simpson (1949) is calculated
as Ds = Σ (ni (ni-1/N (n-1) where Ds = Bias corrected from Simpson index,
n1 is number of individuals of species 1, N = total number of species in community.
As diversity increases index value gets smaller. Pielou (1975)
measures equitability and compares the observed Shannon Weiner index against
the distribution of individuals between the observed species that would maximize
diversity. The index is expressed as J = H/log(S). Menchinicks index
Dmm (Whittaker, 1977) is expressed as Dmm = S/N. Margalef
(1968) is expressed as D = (S-1)/In N. The Shannon Equitability index (EH)
= H/Hmax = H/In. The Fisher α index is a parametric index of
diversity which assumes that the abundance of species follow the log series
distribution. The Berger-Parker Dominance Index is a simple measures of the
numerical importance of the most abundant species and is expressed d= Nmax/N.
RESULTS AND DISCUSSION
Physicochemical conditions of the temple lake are shown in Fig.
2a-o. The water temperature of the lake was ranging from
21.8-29.6°C. Maximum temperature was observed during the month of May and
minimum in February (Fig. 2a). High rainfall was observed
during the month of June and July (Fig. 2b). Generally, surface
water temperature is influenced by the intensity of solar radiation, evaporation,
freshwater influx and cooling (Desai, 1992; Arthur,
2000). Alkaline nature of the study lake was indicated by pH value, maximum
values were observed during the month of May (8.4) and it was declined in July
(7.06) (Fig. 2c). Fluctuations in pH values during different
seasons of the year are attributed to factors like removal of carbon dioxide
by photosynthesis through bi-carbonate degradation, temperature and decomposition
of organic matter (Upadhyay, 1988). The arrivals of
monsoon in June reduce the pH of water and the complete effect of monsoon make
pH level very low during the month of July. Similar result was observed that,
low value of pH for surface and bottom water during monsoon (Kaushik
and Saksena, 1999; Shastree, 1991). Greater inflow
of monsoon rain water from barren rocky land make high volume of water in lake.
Dissolved oxygen is a very important parameter of water quality and an index
of physical and biological process going on in water. Dissolved oxygen content
was fluctuated, the highest value recorded in July (7.52 mg L-1)
and lowest value recorded in the month of May (4.0 mg L-1) (Fig.
2d). In Kerala, south west monsoon starts towards the end of May or the
beginning of June, due to this heavy rainfall, this favours the solubility of
good amount of oxygen in the water. Concentration of DO is one of the most important
parameter to indicate water purity and to determine the distribution and abundance
of various algal groups. The maximum values of BOD recorded during the month
of May (6.2 mg L-1) and it had declined from monsoon (Seenayya,
1971). The minimum concentration was observed in the month of January (1.2
mg L-1) (Fig. 2e). Similar observations were made
by Rahman (1992), Sunkad (2002)
and Hujare (2005) in their studies. Carbon dioxide is
one of the essential constituents of an aquatic ecosystem. The abundance of
carbon dioxide exerts certain specific effects on aquatic biota. The temple
lake exhibited maximum CO2 as 22.0 mg L-1 during the month
of May, whereas the minimum concentration was (6.8 mg L-1) recorded
during April (Fig. 2g). Cole (1975)
noted that free CO2 supply rarely limits the growth of phytoplankton.
Alternately, the bicarbonates are utilized as a source of carbon by the photosynthetic
activity of phytoplankton.
Total alkalinity of the study pond ranged from 26 mg L-1 (January)
to 60 mg L-1 (May) (Fig. 2h). Michael
(1969), alkalinity concentration is effected directly by rainfall. In the
present investigation also alkalinity level reduced in the post rainy months.
Higher level of alkalinity during summer season has been reported by Singh
and Saha (1987). Total dissolved solids values ranged from 48 mg L-1
(July) to 137 mg L-1 (May) (Fig. 2i). The dissolved
solids in a lake and reservoir depend on various parameters such as geological
character of the water shed, rainfall and amount of surface runoff. Silicate
value was low in February (7.5 mg L-1); it increased in May (18.2
mg L-1) (Fig. 2j). In the present study the values
of nitrate ranged from 0.05 to 0.41 mg L-1 showing highest values
in summer months (Fig. 2m). This may be due to the higher
planktonic production, decaying macrophytes and concentration of nutrients get
off from temple and other nutrients owing to the evaporation of lake water with
subsequent increase in nitrate value (Epistein, 1972).
|Fig. 2(a-o): Box plots showing monthly variation
of different physicochemical parameters (a) Temperature, (b) Rainfall, (c)
pH, (d) Dissolved oxygen, (e) BOD, (f) COD, (g) CO2, (h) Total
alkalinity, (i) TDS, (j) Silicate, (k) Magnesium, (l) Phosphate, (m) Nitrate,
(n) Calcium and (o) Chloride contents of Temple Lake Ananthapura
Low level of nitrate may be due to the utilization of phytopolankton for their
luxuriant growth. The amount of calcium was varied in all months, the highest
calcium amount present during the month of May (Fig. 2n).
Chloride values were found ranging from 11.2 to 35 mg L-1 (Fig.
2o) of which maximum value was noticed in the month of June and minimum
value in January may be due to dilution effect of post monsoon period (Chourasia
and Adoni, 1985). The amount of phosphate on lake water was observed probably
due to the presence and decomposition of aquatic vegetation which release phosphate.
Phosphate was found only in smaller amount, the low concentration of phosphate
affects the growth of aquatic flora as it is very essential plant nutrient.
The concentration of phosphate was more in the month of May (0.07 mg L-1)
and less in the month of January (0.02 mg L-1) (Fig.
2l). The estimation of COD is great importance for waters having unfavorable
conditions for the growth of microorganisms; it measures pollution in aquatic
ecosystem (Saxena, 1994). COD value of pond water ranged
from 10.2 to 26.2 mg L-1 (Fig. 2f). Higher concentration
of COD in summer and rainy season may be due to high temperature and higher
concentration of dissolved solids.
The distribution of species indicates that the lake has highest (29) number
during the month of February and June, least distribution was (21) during the
month of April (Table 1). Chlorophyceae were represented in
higher numbers. Gonzalves and Joshi (1964) observed
maximum chlorococcales during summer months.
|Table 1: Phytoplankton population distribution
during the study period (cells mL-1)
The important factors responsible for the formation of blue green algae forms
than euglenoids were increased oxidable organic matter, CO2, phosphate
and calcium (Ramaswamy and Somashekar, 1982). The genera
belonging to class Bacillariophyceae attained their maximum development during
the month of January and February and low or totally absent in some months like
April and May due to their inability to sustain higher temperature and they
might have produced autotoxin resulting their abrupt disappearance. In the present
study euglenophyceae were poorly represented probably due to low carbon dioxide
Table 2 shows phytoplankton diversity indices of lake Ananthapura during the study period. The dominance index in the present study lake the highest dominance of planktonic species was found during the month of April (0.09) and least in the month of February (0.05). The genera Ankistrodesmus, Chlorella and Scenedesmus were the dominant forms in chlorophyceae throughout the study, whereas Lyngbya, Pediastrum and Synedra were found to be the other subdominant forms. The Simpsons index is often used to quantify the biodiversity of habitats. It takes into account the number of species present as well as the abundance of species. The greater the value greater is the sample diversity. According to the Simpsons index, species are not evenly distributed the values range from 0.90 to 0.94 (Table 2).
Shannon and Weiner (1949) represents entropy. It is
a diversity index taking into account the number of individuals as well as the
number of taxa. This index also determines the pollution status of a water body.
Normal values range from 0-4. Wilham and Dorris (1968)
concluded that the values of the index greater than 3 indicate clean water,
1-3 are moderate pollution and value less than 1 are characterized as heavily
polluted. According to this index during the month of February (3.1), the value
was indicates that the lake more diversity, the members like Cyclotella,
Navicula sp. and Ankistrodesmus sp. were considered as the indicators
of clean water. Whereas during the month April (2.5) the value showed less diversity.
Both the Menhinicks and Magalefs indices measures richness of species in an ecosystem. Menhinicks index was low (1.86) in the month of January and reaches high values in the month of May (2.57). Similarly Margalefs index shows higher value (5.78) was during the month of April and lower value was during the month of (4.13) January (Table 2). The Shannon equitability index is a measure of the evenness with which individuals are divided among the taxa present. In the present study which indicates that individuals of the community in all the months were not evenly distributed with value range 0.87 to 0.92.
Fisher et al. (1943) is a mathematical calculation
for determining diversity within a population. It describes the mathematical
relationship between the number of species and the number of individuals of
those species. The index was very low in the month of April (7.1) and was highest
during the month of February (11.7), it indicates that abundance of species
in the month of February. Berger Parkar dominance index (1970) is the number
of individuals in the dominant taxon divided by number of individuals (n). It
is the largest species proportion of all species in a community. This index
is most strongly influenced by evenness of the indices (Shannon
and Weiner 1949). The highest value was observed in the month of April (0.18)
and lowest value was observed in the month of February (0.11).
The Pielou (1975) states that species evenness is diversity
index, a measure of diversity that quantifies how equal the community is numerically.
The index E is a constraint between 0 and 1. Frequent variation in communities
between the species, the higher the values of E. Various diversity measures
have potential application in aquatic ecosystems, mainly in conservation. It
is often understood that species rich communities.
Maximum abundance and diversity of Cyanophyceae (Anabaena; Oscillatoria
and Lyngbya) and euglenophyceae (Euglena and Phacus) were
recorded in the months of April and May when phosphate and BOD values were highest,
indicating that the study lake were rich in nutrients in those months.
|Table 2: Phytoplankton diversity indices
of lake Ananthapura during the study period
|Table 3: Simple correlation coefficient
test between phytoplankton groups and physicochemical parameters of Ananthapura
|Temp.:Temperature, DO: Dissolved oxygen, BOD: Biological oxygen
demand, COD: Chemical oxygen demand, CO2: Carbon dioxide, TA:
Total alkalinity, TDS: Total dissolved solids, SIO4: Silicate,
Mg: Magnesium, PO4: Phosphate, NO3: Nitrate, Ca: Calcium,
Cl: Chloride, CYN: Cyanophyceae, CHL: Chlorophyceae, BAC: Bacillariophyceae,
EUG: Euglenophyceae, *Correlation is significant at 0.05 level (2-tailed),
**Correlation is significant at 0.01 level (2-tailed)
Chlorophyceae genera were rare in the months of April and May. Phytoplankton
population in Ananthapura Temple Lake was found to be maximum during summer;
moderate during winter and minimum during monsoon due to heavy rain (Saify
et al., 1986; Sunkad, 2002; Hujare,
The PCA biplot of axis 1 against axis 2 derived from 15 environmental variables of different months were studied. Figure 3 shows that the first axis was highly correlated with, nitrate, silicate and TDS, to a lesser extent, calcium, magnesium and pH. Therefore, this axis contrasts high nitrate and silicate season, e.g., April and May on the right of the diagram, with low nutrients in January and February, on the left of the diagram. Axis 2 was strongly correlated with the rain fall, COD and chloride, contrasting nutrient rich month, e.g., June at the top of the diagram, with nutrient poor months e.g., January, February at the bottom. Mg2, pH and CO2 appeared to be negatively correlated with axis 2. The difference in the relative size of axis 1 and axis 2 were small (eigenvalues 9.0 and 3.7, respectively).
The simple correlation coefficient test (Table 3) revealed
that the cyanophyceae member was positively correlated with temperature (r =
0.638), phosphate (r = 0.718), nitrate (r = 0.647) biological oxygen demand
(BOD; r = 0.910), chemical oxygen demand (COD; r = 0.929) and chloride (r =
0.934) at 0.01 significant level. Whereas it was negatively correlated with
DO (r = -0.512). Natural factors like alkalinity, nitrate, phosphate are responsible
for the luxuriant growth of cyanophyceae which in turn attributed abundance
of cyanophyceae to higher values of pH, temperature, nitrate, phosphate (Michael,
|Fig. 3: PCA biplot of physicochemical variables
of temple lake Ananthapura
Microcystis are found in polluted waters producing obnoxious odours as well
as toxins. In the present study, very less population of these genera was observed
indicating that the water is free from pollution. The chlorophyceae members
were positive correlation with temperature (r = 0.755), Dissolved Oxygen (DO;
r = 0.527) whereas it was negatively correlated with BOD (r = -0.901), Total
Alkalinity (TA; r = -0.759) at 0.05 and 0.01 level of significant during the
study period (Table 3). In the present study the Mg2
content in lake was found between 5.15 to 11.2 mg L-1 (Fig.
2k) which may have inhibited the growth of desmids.
Bacillariophyceae members have been considered to be the best indicators of
quality and trophic status of the water. They were positively correlated with
rainfall (r = 0.530), COD (r = 0.892), TA (r = 0.642) and chloride (r = 0.791)
at 0.05 and 0.01 significant level. Whereas, it was negatively correlated with
BOD (r = -0.726) and PO4 (r = -0.675) at 0.01 level of significant. Maximum
bacillariophyceae population during rainy and winter season was reported by
Sunkad (2002). Euglenophyceae were positively correlated
with BOD (r = 0.788), COD (r = 0.844), phosphate (r = 0.761) and nitrate (r
= 0.767) at 0.05 significant level. Whereas it was negatively correlated with
DO (r = -0.551) at 0.05 significant level (Table 3). High
level of phosphate and nitrate are influence the growth of euglenophyceae. In
the present study the population of Euglenophyceae was very less compared to
all other forms.
In conclusion, the present study revealed that the Ananthapura Lake is of
a better quality, although there is a need to continuous monitoring for drinking,
irrigation and other purposes. The distribution and population diversity of
phytoplankton species depend upon the physicochemical factors of the environment.
The nine diversity indices explained that the lake showed low level of pollution
with high diversity and presence of different species. So greater the diversity,
less is the impact of environmental pollution; while lesser the diversity greater
is the impact of pollution.
The author expresses his sincere thanks to UGC-SAP New Delhi for the financial
support of this study and Prof. Dr.R. Panneerselvam (HOD) Annamalai University,
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